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I HC QUC GIA H NI

I HC KHOA HC T NHIN

-----------

PHM TH DINH

NGHIN CU BIN TNH PH PHM T CY AY

LM VT LIU X L MT S KIM LOI N O C

LUN V HC S KHOA HC

H Ni 2015

I HC QUC GIA H NI

I HC KHOA HC T NHIN

-----------

Phm Th Dinh

NGHIN CU BIN TNH PH PHM T CY AY

LM VT LIU X L MT S KIM LOI N O C

: K thut mi trng

: 60520320

LUN VN TH S KHOA HC

NGI HNG DN KHOA HC: PGS.TS. QUANG HUY

H NI 2015

i

L I CM

Li u tin, vi lng bit n v s knh trng su sc, ti xin chn thnh

cm n PGS.TS. Quang Huy, B mn Cng ngh Mi trng, Khoa Mi trng,

Trng i hc Khoa hc T nhin giao ti v trc tip hng dn, tn tnh

gip ti trong sut qu trnh thc hin lun vn. Cm n thy rt tm huyt

ch dn v gp ti hon thnh lun vn ny.

Ti xin chn thnh cm n cc thy c thuc B mn Cng ngh mi trng,

B mn Th nhng v mi trng t, Khoa Mi trng, Trng i hc Khoa

hc T nhin, i hc Quc gia H Ni to mi iu kin thun li ti c th

hc tp v lm vic trong sut thi gian nghin cu.

Ti xin cm n ti ThS. Bi Trung Thnh, Trung tm Nghin cu cng ngh

x l mi trng, B Quc phng cng tc trong qu trnh thc hin ti.

Ti cng xin gi li cm n ti gia nh, bn b lun quan tm ng vin v

ng gp kin gip ti trong sut qu trnh hon thin lun vn.

Xin chn thnh cm n!

H Ni, thng nm 2015

Hc vin

Phm Th Dinh

ii

MC LC

LI C N ............................................................................................................. i

DANH MC BNG ................................................................................................. iv

DANH MC HNH NH ........................................................................................ iv

DANH MC CH VIT TT................................................................................ vii

M U ..................................................................................................................... 1

Chng 1 TNG QUAN ....................................................................................... 3

1.1. X l kim loi n tro c bng vt liu c ngun gc thc vt ............... 3

1.1.1. Hin trng nhim kim loi nng trong nc ................................................. 3

1.1.2. X l kim loi nng trong nc bng sinh khi thc vt ................................. 5

1.2. c im sinh hc ca c a ........................................................................ 22

1.3. Tnh hnh sn xut a tr to t gii ......................................................... 23

1.4. Cc mi trng ca c a v sn phm t a ........................... 25

1.5. Tim s dng ph phm c a l m vt liu x l nhim mi trng

.......................................................................................................................... 27

Chng 2 - I V PH PHP HI CU ...................... 30

2.1. i tng nghin cu......................................................................................... 30

2.2. P p p i cu .................................................................................... 30

2.2.1. Phng php bin tnh vt liu ....................................................................... 30

2.2.2. Xc nh c tnh c bn ca vt liu ............................................................. 34

2.2.3. Kho st kh nng hp ph ion kim loi nng ca vt liu bin tnh........ 36

Chng 3 - KT QU NGHIN CU V THO LUN ................................. 37

3.1. c t c bn ca bt t a ....................................................................... 37

iii

3.1.1. c im hnh thi b mt ca bt thn ay .................................................. 37

3.1.2. c im cu trc ca bt thn ay ............................................................... 38

3.1.3. c im lin kt, nhm chc ......................................................................... 39

3.2. Quy trnh bin tnh to vt liu amidoxime ha t bt t a ....................... 40

3.2.1. X l bng dung dch NaOH ........................................................................... 40

3.2.2. ng trng hp ghp acrylonitrile ln bt thn ay bng h khi mo natri

bisunphit/amoni pesunphat (SB/APS) ............................................................ 45

3.2.3. Phn ng amidoxime ho ................................................................................ 52

3.3. c tnh ca vt li bin tnh ....................................................................... 56

3.4. Kh x l kim loi nng (Cu2+

, Zn2+

, Ni2+

) ca vt li bin tnh ....... 60

3.4.1. Xc nh gi tr pH x l ................................................................................. 60

3.4.2. Xc nh cc h s hp ph ca vt liu bin tnh vi cc ion KLN ......... 60

3.4.3. Xc nh thi gian lu ti u cho qu trnh x l ion KLN (Zn2+

, Ni2+

, Cu2+

)

bng vt liu bin tnh ............................................................................... 65

KT LUN V KHUYN NGH ......................................................................... 67

TI LIU THAM KHO ...................................................................................... 69

PH LC ................................................................................................................. 76

iv

DA H MC B

Bng 1. N kim loi n tro c thi ca mt s c s sn xut ............... 4

Bng 2. Di tc , s t v s l a t ca tnh Long An ....................... 24

Bng 3. Di tc , s t v s l a c ca tnh Long An ..................... 25

Bng 4. Thnh ph di dng c trong cc b phn ca c a ......................... 26

Bng 5. ng ca cc iu kin phn n kh p AN l bt thn

a ................................................................................................................ 33

B 6. P p p xc nh mt s tnh cht vt l, ha hc ca vt liu .......... 35

Bng 7. Kt qu xc d lng hp ph ca vt liu ..................................... 61

Bng 8. Cc h s hp ph ng nhit ca vt liu vi Zn2+

, Ni2+

v Cu2+

.............. 63

DA H MC H H H

H 1. c ph hy enzym ca kim loi nng ..................................................... 3

Hnh 2. Cu trc vch t bo v mt ct ngang vi si ................................................. 6

Hnh 3. Cu trc ca phn t cellulose ....................................................................... 7

Hnh 4. Cu trc phn cp ca cellulose ..................................................................... 7

Hnh 5. Vng tinh th v v v nh hnh ca cellulose ......................................... 8

Hnh 6. Cu trc ha hc ca cc hp cht chnh ca hemicellulose ......................... 9

Hnh 7. Cu trc ha hc ca lignin .......................................................................... 10

Hnh 8. Phn ng este ha gia cellulose v axit xitric ............................................ 17

H 9. S cc p p p bin tnh polyme .................................................... 18

Hnh 10. Cc nhm chc ghp ni vo cellulose to vt liu c nhi c tnh tt.......21

H 11. a (Hibisc s a abi s) ................................................................. 23

v

Hnh 12. T trng sn xut a tr t gii ............................................................ 24

Hnh 13. V tr cc nh nhiu x c tr ca cellulose I (a) v cellulose II (b)

trong ph nhiu x tia X ............................................................................ 31

Hnh 14. nh SEM b mt bt t a ................................................................... 37

Hnh 15. Ph nhiu x tia X ca bt t a ........................................................... 38

Hnh 16. Ph hp th hng ngoi ca bt t a .................................................. 39

Hnh 17. ng ca n NaOH n khi lng cn li v m lng

cellulose trong bt t a ....................................................................... 40

Hnh 18. Ph nhiu x tia X ca bt t a ba u v x l cc n dung

dch NaOH khc nhau ................................................................................ 41

Hnh 19. S bi i ch s tinh th ca cellulose trong bt t a k i x l vi

dung dch NaOH cc n khc nhau ............................................... 42

Hnh 20. Ph hp th hng ngoi ca bt t a ba u v x l cc n

NaOH khc nhau ........................................................................................ 43

Hnh 21. ng ca t l SB/APS n kh p AN l bt t a .... 46

Hnh 22. ng ca tng n h k i m o n kh p ca AN ln

bt t a ................................................................................................ 48

Hnh 23. ng ca t l khi l AN/a n kh p AN ln bt

t a ...................................................................................................... 49

Hnh 24. ng ca thi gian phn n kh p AN l bt thn

a .............................................................................................................. 50

Hnh 25. ng ca nhit n kh p AN l bt t a ............ 51

Hnh 26. ng ca n NH2OH.HCl ....................................................... 52

Hnh 27. ng ca nhit phn ng ............................................................. 53

Hnh 28. ng ca thi gian phn ng ............................................................ 54

vi

Hnh 29. Quy trnh bin tnh to vt liu amidoxime ha t bt t a ............... 55

H 30. c im hnh thi b mt ca bt t a ba (a), a x l bng

NaOH 15% (b), a p AN (c) v vt li bin tnh (d) .............. 56

Hnh 31. Ph hp th hng ngoi ca bt t a ba u (a), sau x l NaOH

15% (b) v ghp AN (c) ............................................................................. 57

Hnh 32. Ph hp th hng ngoi ca vt liu .......................................................... 58

Hnh 33. Th zeta ca bt t a ba u, sau x l NaOH 15% v vt liu ....... 59

H 34. in tch m b mt ca vt li bin tnh cc pH khc nhau ................. 60

H 35. P tr p ph ng nhit Freundlich (a) v Langmuir (b) ca vt

liu vi Zn2+

, Ni2+

v Cu2+

......................................................................... 62

Hnh 36. Phn ng to phc gia vt liu amidoxime ha v ion Cu2+

................... 64

Hnh 37. Cc phn ng to thnh vt liu amidoxime ha v phn ng to phc gia

vt liu vi cc ion KLN ............................................................................ 64

Hnh 38. Phc cht gia hai nhm chc amidoxime v ion KLN ............................ 65

Hnh 39. Hiu sut x l kim loi (Zn2+

, Ni2+

, Cu2+

) theo thi gian ca vt liu ..... 66

file:///J:/MAST%20DINH/Mast%20-%20Dinh%20-%2012.1.16.%20final%20%20m,.doc%23_Toc440369513

vii

DA H MC CH VI

AAS : P p p p tch ph hp th nguyn t

AN : Acrylonitrile

FTIR : P p p p tc p hp th hng ngoi

KLN : Kim loi nng

PAN : Polyacrylonitrile

R/L : T l rn/lng

SEM : Knh hi vi in t qut

TCVN : Tiu chun Vit Nam

v/p : Vng/pht

X-ray : P p p iu x tia X

1

M U

Qu trnh cng nghip a t a tr thnh nhn t tch cc i vi

pht trin kinh t x hi ca t c. Tuy nhin, bn cnh nhng li ch m n

mang li, s ia t cc ot ng cng nghip cn sn sinh rt nhiu cc cht thi

c c t cao, tc ng tiu cc n sc khe co i v h sinh thi.

Kim loi nng (KLN) v nhng hp cht ca c c bit cc

cht c tn ti l d i tro mi trng v c kh tc l tro c t sinh

vt. dng vt, chng c th l cc nguyn t vi lng rt cn thit c o c t con

i. Tuy nhin, khi n cao, cc ion KLN li c t c, c th gy ri ro

l d i co i v h sinh thi. Nh tc ng cp tnh do KLN t ng biu

hin nhanh khi tip xc v t ng gy t t n h h hp, tim p nhanh,

suy thn v thm ch gy t vong. Khi nhim v o c th, KLN tch t trong cc m

v gy ra nhng bi i.

C nhi p p p x l c thi cha KLN p p p kt ta

ha hc, trao i io , in ha, hp ph sinh hc, c p p p u c

c im v phm vi ng dng khc nhau. Tuy nhin, cc cng ngh ny yu

cu phi b sung ha cht nn gy nhim th cp hoc gi thnh cao. V vy, vic

lm cp thit l tm ra p p p x l hiu qu v kinh t .

Vic nghin cu s dng cc vt liu t i x l KLN tro c rt

c quan tm trn th gii. l ng nghin cu nhm to ra p p p x

l in, thn thin vi mi trng v b sung t ha cht v gi thnh ph hp.

Vit Nam l mt c c t trng sn xut nng nghip cao, lng ph phm d

tha trong qu trnh ch bin cc sn phm nng nghip l rt ln. Cc ph phm

t ng b b li, thm c l t ngay ti rung gy hu qu nghim tr n

mi trng v n cc v nhn sinh x hi khc.

Vit Nam, khng c nhiu nghin cu v ti ch ph phm nng nghip,

tro c p phm t c a to ra vt liu x l KLN tro c.

2

p v o ng nghin cu tim , ti c n v thc hi ti Nghin cu

bin tnh ph phm t cy ay lm vt liu x l mt s kim loi nng trong nc.

ti c tin hnh vi cc mc c bin tnh ph phm t c a x

l mt s ion KLN (Cu2+

, Ni2+

, Zn2+

) tro c. Ni dung nghin cu tp trung

vo mt s v sau:

- Kho st cc yu t nh hng n qu trnh bin tnh bt g thn cy

ay theo phng php amidoxime ha,

- Kho st cc c tnh c bn ca bt thn ay v vt liu bin tnh,

- nh gi kh nng x l KLN (Cu2+, Ni2+, Zn2+) trong nc ca vt liu

bin tnh.

3

Chng 1 QUA

1.1. X l kim loi nng trong nc bng vt liu c ngun gc thc vt

1.1.1. Hin trng nhim kim loi nng trong nc

Thut ng kim loi nng ch nhng nguyn t kim loi c t trng l 5

g/cm3. Kim loinng tn ti tro c c ngun gc t nhin v nhn to. Theo

ngun gc t nhin, kim loi n i v o tro c do qu trnh phong ha. Bn

cnh qu trnh t nhin, hot ng ca co i p mt ph k gy

nn nhim kim loi n . Tro , c thi t cc k d c, l , s

dng phn bn ha hc, thuc bo v thc vt trong nng nghip, hot ng khai

k o , c thi cng nghip l nhng ngun gy nhim c . c bit, tnh

trng nhim KLN do c thi cc ngnh cng nghip a l mt v mi

trng trn th gii. Cc kim loi ng (Cu), niken (Ni), ch (Pb), thy ngn

(Hg), crom (Cr) v km (Zn) l nhng kim loi t c c tro c thi.

Kim loi nng khng phn hy sinh hc, k c khi dng nguyn t t do

im cho sinh vt sng khi dng cation do kh n kt vi

cc chui cacbon ngn. Mt s kim loi n c tm th tro c t v thit

yu vi sc khe ca co i st, km, ma a , ng, ... Tuy nhin, mc

tha cc nguyn t thit yu ny c th nguy hi i sng sinh vt. Cc kim loi

n t ng tch t tro c, t, trm tch v sinh vt; gy nhim mi trng,

i sng ca cc loi sinh vt v sc khe co i.

V mt sinh ha, cc kim loi nng c i lc vi cc nhm -SH- v nhm -

SCH3- ca cc e z m tro c t (Hnh 1). V th cc enzym b mt hot tnh v

lm cn tr qu trnh tng hp protein ca c t .

Hnh 1. C ch ph hy enzym ca kim loi nng

4

Bng 1. Nng kim loi nng trong nc thi ca mt s c s sn xut [4]

TT K hiu mu Ni

(mg/L)

Zn

(mg/L)

Cu

(mg/L)

Cr(III)

(mg/L)

Cr(VI)

(mg/L)

Pb

(mg/L)

Fe

(mg/L)

1 N1 5,9 7,2 61,2 68,1 71,5 109,5 - 2282,4 24300,0 0,8 1,9 121,1 159,1

3 N2 - 38,5 - - - - -

4 N4 16,9 - 1,89 - - 0,3 0,75

5 N5 73,4 75,5 - - - - - -

6 N6 - 131 - - 2,24 9,8 1,5

7 N7 21,23 12,54 - 116,2 42,4 12,5 -

8 N8 2,29 64,64 - 18,7 - 3,2 -

9 N9 8,17 10,52 - - - - -

10 N10 - 76,5 - - 15,98 - 40,21

QCVN 40:2011/BTNMT ct B 0,5 3 2 1 0,1 0,5 5

Ghi ch:

N1: Cng ty TNHH KYB Vit Nam, c thi b m (12/10/2009)

N2: Cng ty TNHH sn xut ph t t xe m VAP H Y , c

thi trc h thng x l (7/12/2004)

N3: Cng ty OMIC Hi D , c thi c a x l (22/11/2006)

N4: Khu cng nghip Ni B i, c thi ti cng chung (9/11/2005)

N5: Cng ty TNHH Khi H , c thi cng chung (27/9/2003)

N6: s m T Q a x T a T , H T , H Ni (28/10/2003)

N7: s m Tr V Hng x Thanh Thy, H Ty, H Ni (28/10/2003)

N8: Lng St, Hi D , c thi sau cng on ra m (11/11/2003)

N9: Cng ty m i S T , c thi m km (24/3/2003)

5

Cc lng ngh ia c c k , c, m, ti ch v ch tc kim loi c lng

c thi khng l , li cha nhiu kim loi n Z , Fe, r, Ni,...

N cc kim loi n 2+

, Pb2+,

As2+

, Cd2+

, Hg2+

tro c h Thanh

Nhn v h Trc Bch, H Ni vt TCVN 6774:2000 v Cht l c - Cht

l c ngt bo v i sng thy sinh [5].

ng v cc hp cht ca c c c coi l cht c i vi ng vt,

c bit l vi c. i vi thc vt, c coi l nguyn t c bn cn thit cho

s pht trin ca cy tr tro mt s trng hp n li l nhn t c

khi n tro c kho 0,1 m /L. i vi c t i, n ng trong

c ung kho 3 m /L c t vi m v s ng thc qun, nn ma,

thn kinh co git, mch yu, [6].

Km tn ti tro c dng ha tan s rt nguy him n sc khe con

i. Khi ng c km s b a bng, mch chm, co git. i vi cc loi thy

sinh, n Zn2+

bng 0,3 mg/L s gy cht mt s lo i c c ngt [4].

N Ni2+

cao t p i, mi v x . N im c Ni2+

cp tnh

a u, chng mt, bu v a c, kh th, tiu chy, ph thn, vim

da, [4]

c p g php ph bi x l kim loi n l p p p i ma,

trao i io , in phn, kt ta, sinh hc, hp ph bng than hot tnh, Hu ht

cc p p p c c i p cao v t ng c hiu qu khi n ion kim

loi thp. P p p p ph loi b cc ion kim loi tro c c xem l

p p p iu qu cao v chi ph thp [36]. Cc cht hp ph c th l khong

cht, cht h c oc c ngun gc sinh hc.

1.1.2. X l kim loi nng trong nc bng sinh khi thc vt

1.1.2.1. c im ca nguyn liu sinh khi thc vt

Sinh khi thc vt (vt liu lignocellulose) l polyme cacbo irat phc tp,

c thnh phn chnh l cellulose, lignin v hemicellulose [23]. Vt liu

6

lignocellulose c th tm thy trong cht thi nng nghip, nng nghip v cng

nghip m ca, b ma, giy vn, c, thn v l cy, v tru, ng, ...

Lignocellulose l phn chnh hnh thnh nn vch t bo thc vt. Lin kt gia

cellulose, hemicellulose v lignin qua lin kt este v ete lm cho sinh khi c tnh

bn vng [31]. Cc vi si cellulose c bao quanh bi hemicellulose to thnh

mt m li m, m khong khng gian tr c lp y bng lignin (Hnh 2).

Hnh 2. Cu trc vch t bo v mt ct ngang vi si

Cc thnh phn ca sinh khi khc nhau ty thuc v o cc lo i v iu kin

mi trng sng. Thnh phn trung bnh tnh theo tr lng ca ba polyme sinh

hc sa : cellulose (30-50%), hemicellulose (19-45%) v lignin (15-35%) [31].

Cellulose l hp cht h c c c t c cu to (C6H10O5)n v l mt

polyme mch thng ng nht gm cc phn t glucose lin kt vi

nhau bi lin kt -1,4-glicozit v lin kt hydro ni phn t v gia cc phn t

[34]. Mi v lp li trong cellulose cha hai phn t anhydroglucose (AGU).

Mi v lp li c mt nhm hydroxyl (OH) chnh cc v tr cacbon 6 (C6) v

hai nhm hydroxyl th cp ti v tr 2 v 3. v lp li th hai xoay 180o

7

trong mt phng (Hnh 3). Cellulose c nhi m a c hydrox l t ta

tro c do lin kt ni phn t v lin phn t mnh.

Hnh 3. Cu trc ca phn t cellulose

trng hp ca cellulose l 300 - 1700 vi si g; 800 - 10000 vi cotton,

si thc vt v cn ph thuc vo cellulose gc a q a x l [23].

Hnh 4. Cu trc phn cp ca cellulose

Cc si cellulose nm thnh t bo thc vt v c to nn bi cc vi si

(Hnh 4). Cc b vi si cha 30 - 40 mch cellulose t eo cc ng khc nhau v

c hnh thnh bi cc i phn t cellulose dng tm [33]. Cc mch cellulose

c lin kt vi nhau nh lin kt hydro v lin kt Van Der Waals. Do thiu

chui bn hoc chui nhnh, cellulose l mt polyme bn tinh th, cha c pha tinh

th v p a v nh hnh [28] (Hnh 5). Lin kt hydro gia cc chui cellulose v

lc Van Der Waals gia cc phn t glucose d n s hnh thnh vng tinh th.

Trong vng tinh th, cc phn t cellulose lin kt cht ch vi nhau, vng ny kh

b tn cng bi enzym c a c t. Ch c cc mch cellulose trn b mt cc

vi si l d dng tip xc vi ha cht. Do , p n ng thy phn ca cellulose l

8

rt thp [31]. N c li, tro v v nh hnh, cellulose lin kt khng cht vi

nhau nn d b tn cng [14]. t k p n ng ca cellulose, cc vng

tinh th ca cellulose c c chuyn sang d v nh hnh. Vi mc c ,

mt s qu trnh thy phn b p p p a c c nghin cu.

Vng v nh hnh

Vng tinh th

Hnh 5. Vng tinh th v vng v nh hnh ca cellulose

Cellulose c hai dng tinh th l cellulose I v cellulose II [28]. Cellulose I

c cc chui cellulose sp xp song song vi nhau, trong khi cc chui cellulose II

i song vi nhau. Cc d v nh hnh ca cellulose l dng III v dng IV.

Cellulose I t ng c trong cellulose t nhin. Trong cellulose I c hai loi lin kt

hydro: lin kt hydro ni phn t v gia cc phn t [28]. Lin kt hydro ni phn

t gm hai loi: O-2-HO-6 c di lin kt l 2,707 v O-3-HO-5 c di

lin kt l 2,802 . Lin kt hydro lin phn t gia C6-OH v C3 (O6 - HO3) c

di lin kt 2,874 [49]. Cu trc ny rt bn nhit v c th c chuyn sang

cc dng cellulose khc [28, 14]. Cu trc tinh th ca cellulose I c th chuyn

sang dng cellulose II thng qua qu trnh x l bng kim.

Hemicellulose l mt polysaccarit c tnh cht ha hc khc nhau gia cc

loi thc vt, c hnh thnh bi pentose (xylose, rhamnose v arabinose), hexose

(glucose, manose v glactose) v cc axit uronic (4-Omethyl-glucuronic, v

galacturonic) [34]. Xylan polyme l loi polyme ph bin nht trong hemicellulose.

Hemicellulose bao hm cc lin kt (1-4) khng phn nhnh ca xylan hoc

mannan, chui xon c li kt (1-3), chui p li kt (1-4)

galactoglucomannan (Hnh 6). Kt qu hnh thnh chui polyme phn nhnh m

ch yu gm cc mo ome m cacbo (x lose) v ng su cacbon

9

(glucose). Hemicellulose khng c cu trc tinh th, cu trc phn nhnh cao v c

cc nhm axetyl kt ni cc chui polyme vi nhau [23].

a) Xylan

b) Glucomannan

Hnh 6. Cu trc ha hc ca cc hp cht chnh ca hemicellulose

Hemicellulose k a ta tro c nhit thp. Tuy nhin, qu

trnh thy phn ca cao so vi cellulose [23]. Hemicellulose tan nhi

trong dung dch axit. H m lng hemicellulose trong g mm v g cng khc nhau

k. Hemicellulose lm gim kh tip cn cellulose, do , cn phi tch

ti thiu 50% hemicellulose t k ca cellulose [34]. So vi cellulose,

hemicellulose d dng b thy phn trong axit long, kim hoc e z m. Do nhy

nhit cao, qu trnh thy phn hemicellulose to ra cc sn phm ph khng mong

mu f furan v hydroxymetyl fufuran.

Lignin l mt hp cht c cu trc phn t phc tp cha polyme lin kt

ngang ca cc p p e olic, c bit l p-coumaryl ancol, coniferyl ancol,

sinapyl ancol (Hnh 7).

10

Hnh 7. Cu trc ha hc ca lignin

Li i c vai tr mt mng bo v tnh thm ca t bo v c n s

xm nhp ca vi khun. V c bn, cc loi thc vt g mm cha m lng lignin

cao so vi cc loi sinh khi thc vt k c, do q tr tc cellulose t

thc vt g mm t k k so vi cc sinh khi k c. Do , loi b

lignin cn phi thc hin cellulose v hemicellulose c tip xc vi dung

dch x l [31].

Vt liu lignocellulose l ngun ti nguyn ti to, c th s dng trc tip

hoc gin tip sn xut cc kh sinh hc hoc cht ha hc, vt liu x l [3].

Mt cht hp ph c coi l c chi ph thp nu n phong ph trong t nhin v l

ph phm nng nghip, cng nghip [47]. Ngun cht thi t sinh khi thc vt c

gi tr kinh t thp. Tuy nhin, cc ng dng ca ngun ti nguyn ny b hn ch

bi lin kt cht ch gia ba thnh phn chnh ca thnh t bo l cellulose,

hemicellulose, lignin.

11

1.1.2.2. s ca p p p

Ph phm nng nghip t ng gm cc thnh phn cellulose, hemicellulose,

lignin, lipid, protein, cc loi , ti bt, c, hidrocacbon, tro. Nhng

vt liu ny c kh p ph kim loi nng nh cu trc nhiu l xp v thnh

phn gm cc nhm chc hot ng [3]. Cc nhm chc trong sinh khi bao gm

nhm axetamido, cacbonyl, phenolic, khung polysaccarit, amin, sunphua hydryl,

cacboxyl, ru v este [19]. Cc nhm ny to i lc v to phc vi ion KLN. Mt

s vt liu hp ph lin kt khng chn lc, c th lin kt vi nhiu ion KLN.

Trong khi, cc vt liu khc lin kt chn lc ion KLN ph thuc vo thnh phn

ha hc ca chng. Cc ph phm x da, tru, b ma, l c c , c d

x, t c , thn cy chui, v tr , t c ,... c nghin cu

nhm pht hin kh tc kim loi n tro c.

Trao i io l c c quan tr i vi qu trnh x l ion KLN bng thn

c o c tm thy trong nghin c c b [25]. Sau khi hp ph Cu2+

,

Ni2+

, Pb2+

v Cd2+

, kt qu phn tch cho thy cation Ca2+

, Mg2+

, K+

v H+

c

tch ra khi vt liu c t l g t vi ion kim loi c x l. iu

ny chng t cc ion KLN t a t v tr ca cc cation khc trong vt liu.

P tr p n trao i io sa :

S M2/n + Me2+

S Me + (2/n) Mn+

(1)

Tro , S l v tr lin kt, Mn+

i din cho ion K+, Mg

2+, Ca

2+ v Me

2+

i din cho cc ion KLN.

C d x cha phn h c c yu l lignin, cellulose v mt s nhm

chc phn cc [52]. Nhng nhm chc ny c kh trao i cation hoc to

lin kt ha hc. Phn ng hp ph trao i gia Cu v sinh khi d x c th

biu di t eo p tr sa :

2(TF)- + Cu

2+ Cu(TF)2 (2)

2H(TF) + Cu2+

Cu(TF)2 + 2H+ (3)

12

Tro , (TF)- v (TF) l nhng v tr phn cc c th t tc vi cc ion

kim loi trn b mt vt liu t sinh khi d x.

Ion KLN tn ti mt s dng trong dung dc e2+

, MeOH+,

Me(OH)2, Cc ion kim loi tn ti trong dung dch axit cc dng cation.

Trng hp , c c ch y l trao i ion. Ti pH cao, cc ion kim loi s kt

ta, do , iai o , c c hp ph b mt chim t . c c c ny

c th hin qua cc p tr sa [10]:

2(R-COH) + Me2+

(R-CO)2Me + 2H+ (4)

R-COH + MeOH+ R-COMeOH + H

+ (5)

2R-COH + Me(OH)2 (R-COH)2Me(OH)2 (6)

Tro , R l cc gc trong vt liu.

N c , c c hp ph ion KLN bng ph phm nng nghip da trn

phn ng ha hc gia cc nhm chc trn b mt cht hp ph v ion kim loi.

Phn trao i cation v phn ng to phc vi ion kim loi l ch yu. Bn

cnh , cc c c xy ra km theo bao gm hp ph b mt, khuch tn, kt ta.

im ca vic s dng ph phm nng nghip x l c thi bao

gm k thut in, kh p ph tt, hp ph chn lc ion kim loi nng,

chi ph thp, tnh sn c v d dng ti sinh. Tuy nhin, vic p dng cc cht thi

t sinh khi thc vt c a c x l c th mang li mt s v l m t

OD, BOD c TO tro c do s ha tan ca cc cht h c d ha tan

trong thc vt [47]. S ia t OD, BOD v TOC ca c c th gy ra s suy

gim oxi tro c, d e da i sng th si . Do , vt liu c

ngun gc thc vt c c x l trc khi hp ph kim loi nng.

1.1.2.3. Mt s p p p iu ch vt liu t sinh khi thc vt

Trong nh m , vic s dng ph phm nng nghip c c

bit quan tm, nhiu nghin c c tin hnh nhm tm ra p p p c n

cc ph phm ny thnh vt liu c ch. Tro , ng nghin cu s dng ph

13

phm nng nghip lm vt liu x l KLN tro c l mt trong nh ng c

tim ng dng nht.

Sinh khi thc vt c cellulose c a bin tnh c kh p ph

kim loi nng thp v tnh cht vt l khng nh. khc phc nh im hn

ch ca sinh khi t , cc p p p bi t c p d nng cao hiu

qu x l KLN. Mt s nhm p p p c s dng nhiu nht c phn loi

sa : p p p vt l (xay v nghin, nhit); p p p a c (bin tnh

bng kim, axit, tc nhn oxi ha, dung mi h c); p p p si c; t hp

ca p p p vt l v p p p a c (qu trnh t thy phn, oxi ha

t).

P p p si c c p d phn hy mt phn vt liu

lignocellulose bng cch s dng cc vi sinh vt phn hy lignin v hemicellulose

m v vi khun. im ca p p p l tin hnh d dng v tn t

lng. Tuy nhin, qu trnh phn hy sinh hc din ra chm v cn p dng

t m cc p p p vt l, ha hc k c p p p i c c. Cc

p php vt l in, chiu x, nhit c c p d bi i

tnh cht ca sinh khi thc vt. P p p i l m t din tch b mt v

gim tinh th ca cellulose. P p p c iu x nhm ph v cc lin kt

hidro trong cu trc tinh th ca cellulose b lng bc x. Tuy nhin,

p p p cu phi cung cp lng l . c p p p a c

s dng cc cht ha hc bin tnh vt liu. Mc c ca p p p l

th p emicell lose, li i ng thi t m lng cellulose trong sinh khi

thc vt. P p p bin tnh kt hp p p p vt l v p p p a

hc t c p d v c coi l p p p tt nht.

Hai p p p bin tnh sinh khi thc vt thnh vt liu t c p

dng v nghin c l p p p c to than hot t v p p p bin tnh

b mt.

14

a) Ch to than hot tnh

Than hot t c s dng rng ri trong x l cc cht nhim h c v

cc ion kim loi n thp. Cacbon trong thc vt c chuyn ha thnh

cacbon hot ha nhit cao. Than hot tnh c thnh phn ch yu l cacbon

(85-90%), cn li l cc hp cht v c dng tro (5-15%). Than hot tnh c cu

trc l xp. Din tch b mt trong cc l xp chim phn ln tng din tch b mt

ca cacbon [12].

Cht thi nng nghip l ngun nguyn li p o p sn xut than hot

t do c m lng tro thp v cng ph hp [24]. Do , bin tnh cc cht

thi nng nghip thnh than hot tnh l mt gii php gii quyt v mi trng

v gim chi ph ch to than hot tnh. Than hot t c ch to t cht thi rn

nng nghip m ca, c t thi cao l , li ng, b ma, tr , x da,

c s d loi b KLN v x l cht thi dt nhum tro c [12]. Than

hot tnh ch to t ph ph phm nng nghip c hiu qu kinh t cao trong x l

c thi do ngun nguyn liu di do, gi thnh r.

b) Bin tnh ha hc

Mc tiu quan trng ca bin tnh bng cc cht ha hc l to ra b mt m

in hoc i tc d trn b mt ca vt liu [44]. iu ny lm cho

kh p t keo tt v iu ch c tnh b mt ca vt liu.

Cc chui cellulose cha mt nhm hydroxyl chnh v hai nhm hydroxyl

th cp. Cc nhm chc hot c gn vo cc nhm hydroxyl bng cc cht

ha hc [18]. c p p p bin tnh ha hc chnh bao gm: este ha bng axit

h c, oxi a bng cc tc nhn oxi ha, thy phn bng dung dch kim v ghp

cc monome ln sinh khi thc vt. c p p p bin tnh sinh khi thc vt

c th tc c cc hp cht h c a ta v cao iu qu to phc vi

KLN [36]. Lignin c cha nhiu nhm chc drox l t do, nhm metoxyl,

nhm cacbonyl v ni i, do , c t tham gia cc phn oxi a l m t

mch cacbon to thnh axit bo v v t m. c d lignin c kh bn nhit

15

tt, nng chy nhit 140 - 160 , d b s im b do tia t oi.

V t m trc k i c to vt li c p i x l si loi b li i .

Hemicellulose c c trc c v , o i ra c mt t t ti v

ti t ca cellulose. V v , d b t p tro d dc axit, d b trc l

k i si tro d dc kim lo , d p p m, c k t p di

tc d ca vi k v l m s im b it ca vt li , t c t c c

km, k b . Bin tnh ha hc khng nhng loi b lignin, hemicellulose m

cn lm gim m lng tinh cellulose tinh th v t xp ca b mt vt liu.

c iu nghin cu v p p p bin tnh vt liu bng cch s dng cc

tc nhn bin tnh k c a cc d dch kim (NaOH, Ca(OH)2, Na2CO3),

cc axit v c (H l, H2SO4, HNO3), cc axit h c (axit tartaric, axit xitric) hay

cc hp cht h c (meta ol, focmalde t), cc tc nhn oxi ha (H2O2, phn ng

Fe to ) x l cc cht h c a ta , mu v hp ph kim loi nng trong

c. Tc nhn bin tnh l m t t ot ng ca b mt vt liu do gn thm

cc nhm chc c kh kt hp vi kim loi nng, loi b cc cht h c d

ha tan c sn trong vt liu.

Bin tnh bng dung dch axit v c

Bin tnh bng dung dch axit l qu trnh ph v cu trc bn vng ca vt

liu lignocellulose. Ion H+ ph v lin kt ni phn t v lin kt gia cc phn t

vi nhau gia cellulose, hemicellulose, lignin trong sinh khi [31]. c axit c

H2SO4, HCl, H3PO4 v HNO3 c p d thy phn sinh khi. Cc nhm

hydroxyl trn cellulose vai tr q a trng v kh trao i ion ca vt liu

lignocellulose. Bn thn nhm ny ny c kh trao i yu v lin kt OH

phn cc khng mnh. Nhiu bin php bi t c cng b oxi a cc

nhm hydroxyl thnh cc nhm chc axit hoc sunfo ha bng axit sunfuric [3].

Tuy nhin, cht thi t qu trnh bin tnh bng axit c c x l do c t c

hi, m . Hu ht cc p p p bin tnh sinh khi thc vt b axit v c

u s dng dung dc axit lo axit H2SO4, HCl v HNO3. Cc axit long c

hiu qu v mt c i p v mi trng. Nhn chung, axit long (H2SO4 < 4%)

16

c th ha tan hu ht hemicellulose [31]. Dung dch axit H2SO4 lo l m t tc

phn ng thy phn cellulose. Axit m c l tc nhn oxi ha mnh cho qu

trnh thy phn cellulose c t m v p i thu hi. M ca c x

l bng HCl loi b c 92,4% Cu2+

pH 5, tro k i m ca c loi b c

47% [36]. Tuy nhin, trong mt s trng hp, x l v tru bng HCl li lm gim

kh p ph Cd2+

so vi v tru khng x l b axit. hp ph cc

KLN, b mt cc vt liu hp ph phi ma in tch m. Mc d bin tnh bng

axit lm gim m lng cht h c ca vt liu hp ph v t xp b

mt tc i d vi cc ion H+ c l m cn tr qu trnh hp ph. Khi v tru

c x l bng HCl, cc v tr hp ph trn b mt vt li c proton ha.

Bin tnh bng dung dch kim

Trong thnh phn si thc vt v g c cellulose, hemicellulose, lignin l cc

thnh phn ng l n tnh cht ca si. c c c ca q tr bi

tnh b kim l p v c trc li i tro si k i, l m t mc p

ca cellulose v hemicellulose c o cc bc x l tip t eo. Q tr t p

b d dc kim d d x ra ( it di 140 ) so vi cc p p p

bi t k c [31]. xp ca vt li t l sa k i d dc kim p v cc

li kt c o, to t m i ca axit cacbox lic v r . Vt li c bi t

b d dc kim c b mt m i do cc io H+ trong cc nhm hydroxyl,

cacboxyl, ... c s tr b mt vt li c tc ra tr a io OH- trong

d dc . i l im ca p p p bi t vt li b d dc

kim so vi cc p p p k c. Nhn chung, cc d dc NaOH v a(OH)2,

NH4OH t c s d c o q tr t p b kim.

Bin tnh bng axit hu c

Cc axit h c c tc dng este ha cellulose, g c d l r v v

c hot ha bng axit xitric u c mt s ia t k kh

loi b cc ion kim loi tro c [3]. Axit xitric u tin s chuyn thnh dng

anhydric, tip theo l phn ng este ha xy ra gia axit anhydric v cc nhm

17

hydroxyl ca cellulose. Ti v tr phn v x t hin hai nhm chc axit

(t axit xitric) c kh trao i ion. N t it hoc ko di thi gian

phn ng, qu trnh este ha c th tip tc x ra i vi cc nhm axit cn li ca

axit xitric lm gim kh trao i ion.

Hnh 8. Phn ng este ha gia cellulose v axit xitric

Nghin cu v qu trnh este ha bt li ng bng axit xitric cho thy, sau

khi este ha, din tch b mt ca cht hp ph t k [3]. Lng oxi c

tm thy trong vt li t cao do iu nhm oxi a c gn trn b mt vt

li , in hnh l nhm cacboxyl, phenolic v lactonic.

Bin tnh bng dung mi hu c

Bin tnh bng dung mi h c loi b lignin, hemicellulose ra khi vt liu

bng cch solvat ha, ha tan cc mnh v ca lignin, hemicellulose. Cc polyme

lignin d dng tan trong dung mi h c. Qu trnh solvat a c thc hin bi

cc lc gia cc phn t li kt hydro, lc ion-lng cc, lc lng cc, lc

lng cc-lng cc gy ra [36]. c d mi c s d bin tnh vt liu

18

c ngun gc thc vt t ng c nhit si thp meta ol, eta ol, axeton,

etylen glycol, etyl axetat. Ion OH- trong ancol s ph v lin kt axit-este trong

lignin, hemicellulose. H a, bin tnh bng dung mi h c c l m cellulose

tr l , do im lng cellulose tinh th. T i , p p p k

kh thi v mt kinh t v i i phi thu hi dung mi h c.

Bin tnh bng tc nhn oxi ha

Mt s tc nhn oxi a t c d bin tnh sinh khi thc vt

thnh vt liu hp ph bao gm ozon, hydropeoxit (H2O2), clo, H l, H lO, Cc

tc nhn oxi ha tham gia vo qu trnh ha tan lignin bng cch ph v cu trc

vng ca lignin. T t ng, tc nhn oxi a c s d h tr cho bin

tnh bng kim. Tro iu kin pH > 12, gc ( O2*) hnh thnh v m v t m

[31]. Lignin, hemicellulose b ha tan thnh axit cacboxylic (axit formic, axit

oxalic, axit axetic); tro k i , cellulose h k b phn hy.

Bin tnh sinh khi thc vt bng phn ng ng trng hp ghp

Hnh 9. S cc phng php bin tnh polyme

19

Mt s p p p bi i cc thuc tnh ca polyme bao gm pha

trn (blending), ghp (graft) v che ph (curing) [13]. Hn hp ca hai hay nhiu

monome c pha trn vt l vi a c c cc tnh cht cn thit l qu

trnh pha trn. Ghp l mt p p p tro monome c lin kt cng ha

tr vo chui polyme. Che ph l qu trnh bao ph ca mt lp p t ln mt

chui polyme bng cc lc vt l.

Q tr ng trng hp l qu trnh trng hp hai hay nhiu monome m

sn phm polyme sinh ra c cc mt xch monome sp xp ngu nhin (copolyme

ngu nhin), sp xp l p i n hoc cc mt xch monome khc nhau to

t cc on mch khc nhau trn polyme (copolyme khi) hoc polyme c

nhnh to ra t monome khc loi vi mch chnh (copolyme ghp). Khi trng hp

mt loi mo ome to nn mc v o mt loi polyme c sn, qu

trnh ny gi l ng trng hp ghp, sn phm ca qu trnh l copolyme ghp.

ng trng hp p l p p p t c s dng rng r i bin tnh

ha hc cc polyme t nhin v polyme tng hp. Phn ng trng hp ghp l

mt p p p t c s d bin tnh b mt pol me v t a i cc

thuc tnh vt l hoc ha hc ca polyme. Cc chui b c lin kt cng ha tr

vi trc pol me c hnh mt cht ng trng hp (copolyme). C hai loi

chnh ca p p p p ni l ghp ni vi mt mo ome v p ni vi

mt hn hp ca hai hay nhiu monome. Ghp ni vi mt mo ome t ng xy ra

trong mt bc duy nht, trong khi ghp ni vi hn hp monome c th xy ra

vic ghp ni tun t hoc ng thi hai monome.

P p p ng trng hp ghp cc monome khc nhau ln cellulose hoc

vt liu lignocellulose c p d x l c nhim mu, kim loi nng.

Bin tnh vt liu lignocellulose t nhin bng phn ng trng hp ghp cc

monome c cha nhm vinyl ci thi c mt s c im ca vt liu th

m v ca vt liu, tnh khng thm c, nh nhit, i, trao

i ion, hn ch s xm nhp ca cc vi sinh vt [29]. Qu trnh ghp cc monome

vinyl ln cellulose hoc vt liu lignocellulose t ng bao gm ba bc, (1) cc v

20

tr hot ng trn b mt pol me c si ra, (2) cc mo ome c thm vo phn

ng, (3) mo ome c ghp vo vt liu. Cc v tr hot ng trn mch cellulose

c to ra bi phn k i m o bng ha cht hoc bc x.

Phn ng trng hp ln cellulose ch y c thc hin trong mi

tr c v mi tr k ng nht. Tro c, cc vn v nh hnh

ca cellulose tr l , mch cellulose tr nn d tip cn, cc monome khuch

tn vo cc vng ny v ghp ln mch. Do , t iu qu ghp, vt li c

l m tr trc khi ghp hoc thc hin phn p tro mi trng c kh

l m cellulose tr l . K i tr p p l cellulose trong mi

tr k t, k tip c cc c t do tr cellulose v nhm

vi l l mt t am s q a tr xc i q p. c d, cellulose l mt

pol me t , t i , s i di ca cc v ti t v cc li kt dro

ia cc p t l m im k tip c [28]. Tro c, s tr ia

cc ti t ca cellulose x ra c l v v , v l m t

i q p. P tr p p x ra tt tr v v

ca cellulose do k tip c d d ca v . t i q p c

t t t l cellulose/mo ome, l m tr cellulose trc k i p , oc

ti p p tro mi tr l m tr cellulose. c p

php zn ha, oxi ha, bin tnh vi dung dch kim, c, ami c p d

ci thin kh tip cn ca cellulose. t , k tip c a k

p ca cellulose t k i m l ti t im, m l v

t . Tro q tr x l kim, cellulose c tr v trt t c trc b p

v. trc ti t ca cc c i cellulose so so ba c sp xp li

t cc c i i so so , do t cellulose II [48]. t i, m

l cellulose v t , li i , hemicellulose c c tc ra k i vt

li .

Ty thuc v o cc mo ome c ghp ln vt liu, cc thuc tnh ca sn

phm ghp s khc nhau. Nhn chung, cc nhm chc ph bi c s dng trong

p mo ome c th hin trn hnh 10 [44].

21

Hnh 10. Cc nhm chc ghp ni vo cellulose to vt liu c nhiu c tnh tt [44]

B cc ng trng hp ghp ni cc monome, cc nhm chc mi c

to ra trn b mt vt liu. Tro , acrylonitrile l m mo ome c s dng

ph bin. Vt liu cellulose c ghp vi acrylonitrile v cc monome khc c

d x l cc ion kim loi nng Cd2+

, Cu2+

, Zn2+

, Cr2+

tro c [44]. Kt qu

cho thy, sn phm ghp nng cao kh li kt vi cc ion kim loi n

cellulose ba u, kh li kt ph thuc vo ion kim loi v c tnh ca vt

liu ghp.

Qu trnh ghp c th c thc hi tro mi tr ng nht hoc

k ng nht. K i ng trng hp ghp din ra tro mi tr k ng

nht, phn c tin hnh bi tc k i m o p hp [44].

22

tng hp copolyme ghp ta c th d cc p p p: ng trng hp

gc t do, ng trng hp ion v mt s p p p k c. Cc k thut k i m o

cho qu trnh ghp bao gm ha cht, tia x, quang ha, plasma v ghp enzym.

Tro , k thut k i m o bng ha cht l p p p t c p dng

do chi ph thp v t c hi. Vai tr ca cht k i m o l rt quan trng v n quyt

nh cch thc ghp. Tro trng hp p t eo c c gc t do, cc h khi

mo khc a eri (IV) amo i itrat ( AN), m i pesunphat, tc nhn oxi

ha Fenton (Fe(II)-H2O2), KMnO4-axit oxalic, natri bisunphit/pesunphat l nhng

cht k i m o c s dng v nghin cu. So vi cc q tr k i m o k c,

k i m o t eo c c gc t do c im l c th tin hnh nhit phng v

t c hi.

1.2. c im sinh hc ca cy ay [7, 8]

a c tn khoa hc l Hibiscus cannabinus, thuc chi Hibiscus, h

Malvaceae (h Cm Qu), c khong 40 - 50 loi phn b khp vng nhit i v

cn nhit i. S a l loi si c sn xut v s dng nhiu th hai sau si

cotton. a p t trin tt trn t bi bi, t laterite, t vi vi cp ht t

ct tht n st tht, t kh vi pH t 5,5 - 6,5. a c t pht trin t 1,5 - 4,5

m, t c ng knh khong 1 - 2 cm. l loi cy ngn ngy, cho hoa ti 4

t trc khi ra ht vo cui t i ma. a p t trin kh hu nng v m

t vi khong nhit t 24 n 37C hoc c th cao . l loi cy kh

nhy vi nhit v nh sng nn n cn mt thi im thch hp gieo ht v

thu hoch. iu ki l tng th c th thu hoch sau 100 - 120 ngy k t ngy

gieo ht.

23

Hnh 11. Cy ay (Hibiscus Cannabinus)

T c a bao m 2 dng si: si o i c gi l lp v libe v chim

khong 40% tr lng cht kh ca thn; si bn trong c mu tr c gi l

si t v c im khong 60% tr lng kh ca thn. Si t a rt chc, t

vi si g loi chc c s d sn xut cc loi giy khc nhau. Phn

th c a c o bt c x si ng , ng knh ln, t l di/r t x

si bt g cng. Thnh phn ha hc chnh ca c a bao m: cellulose (43 -

46%), pentozan (11 - 16%), lignin (21 - 29%) v tro (1,6 - 2,6%).

1.3. Tnh hnh sn xut ay trn ton th gii [7, 8]

i trng ngy cng nhim ch yu do s khai thc qu mc ti nguyn

thin nhin cng s bng n ca th trng sn phm tng hp, nguyn vt liu ti

sinh d c ch nhi cc quc gia pht tri v a p t trin. Si ay

tr nn quan trng bi cc c tnh ha hc vt l c t t i mi trng.

v Bangladesh l cc quc gia c s l a chim n trn 85%

ca ton th gii. Trung Quc, Myanmar v Nepal c trng v sn xut a . c

quc gia sn xut vi din tch nh l Vit Nam, Thi Lan, Indonexia v

Campuchia (Hnh 12).

24

Hnh 12. T trng sn xut ay trn th gii

Vit Nam, din tch tr a ln nht l v o m 1987 vi quy m

31.956 ha v s lng 57.576 tn si t. N c , din tch v s l a c

x ng gim trong 3 thp k qua. Hi a , c a c trng ch yu ti Long

An. Di tc , s t v s l a t v a c Lo A c th hin

trong bng 2 v 3.

Bng 2. Din tch, nng sut v sn lng ay t ca tnh Long An

m Din tch

(ha)

ng sut ay t

(tn/ha)

Sn lng ay t

(tn)

2007 8.616 1,70 14,647

2008 1.708 2,01 3,433

2009 1.188 2,16 2,566

2010 2.799,4 1,91 5,347

2011 3.330 1,87 6,227

25

Bng 3. Din tch, nng sut v sn lng ay cy ca tnh Long An

m Din tch

(ha)

ng sut ay cy

(tn/ha)

Sn lng ay cy

(tn)

2007 185,0 24,8 4.588

2010 127,5 40,0 5.100

2011 106,4 35,0 3.724

1.4. Cc nh hng mi trng ca cy ay v sn phm t ay [8]

a c k ng ha kh CO2, loi kh nh knh chnh gy nn bi i

kh hu. Ging cc loi c k c, a c s dng CO2 to ng. Trong 120

ngy ca k a a p t trin, mt ha cy tr a c t hp th khong 15 tn

CO2 t kh quyn v gii phng khong 11 tn oxi v cc cht khc. Cc nghin cu

c c o t y rng t l ng ho CO2 a l cao so vi cc loi cy khc

nhiu ln.

c tc mi trng ca sn xut a l t i so vi vic sn xut

si tng hp. N i tr a s dng s lng t cc loi phn bn ha hc v

thuc dit c. N s t a khong 5 - 10 tn cht kh mi m t. Khong 1 tn

cht kh t l c a tr li t v khong 3 tn r v c tro t. Cy a

ip t cng cht h c tro t do l rng tro ma si trng v ci thin

l di d tro t. a t c trng lun canh vi c l t c

k c o v cc loi cc, rau qu, ht c du, tt c s p thuc va

phi hoc nhiu vo cht di d c tro t, t ng khng tr li cho

t, ngoi tr tro trng hp cc cy h , a . P p p l ca

khng ch l m t sn xut nng nghip, m cn duy tr mc ph nhiu ca t

ch yu l thng qua phn hy ca l rng v cht thi h c t a .

a l mt cy tr m t och t nht mi m mt l . a l

mt loi cy l x, pht trin nhanh khi mt kho 4 t tr t . iu

26

c a l iu sut sinh hc ca si a l cao iu so vi cc cy ly

g, v do vic s dng si a t a c o d sn xut bt giy s lm

gim chi ph sn xut n mt mc l . N c s lm gim nhu cu cht cy

ph rng.

Trong nng nghip tr a , vic s dng phn bn, thuc tr su v thuc

dit c/thuc dit nm l hn ch. Mc dng phn ha hc cho tr c a l

t 7 - 53 kg cht di dng cho mi ha. S lng phn bn s dng nh ti mc

ng c th c coi l k k. C l r a rng khong 5 - 6

tn l cy trn mt hecta. Mi cy a c k ong 100 - 120 l, do ip im bc

i c t t. R a d i c k m x do ip di c n dinh

dng v lun canh cy tr k ai t c s t cao . L c rng sau khi thu

hoch rt i di dng, l ngun phn bn cho v ma tip theo.

Bng 4. Thnh phn dinh dng c trong cc b phn ca cy ay

B phn it (%) Pht pho (%) Kali (%)

L 2,85 3,60 0,85 1,20 2,50 3,10

Thn 0,17 0,25 0,21 0,28 0,50 0,82

R 0,35 0,46 0,35 0,46 1,50 1,80

Ni chung phn h c l ngun phn bn ch yu trong qu trnh gieo trng

a s lng nh cc loi phn bn ha hc c t c s dng. Tuy

nhin, hu ht cc thuc tr su, n c s d , c loi b trong qu

ngm, sn xut si a . Thuc tr su s dng trong nng nghip a c c tnh

l 0,5 kg/ a, t vi 0,25 kg ca thuc tr su trn tn sn phm.

Q tr m a v cht thi: a c ngm trong c 2 - 3 tun, qu

trnh tn ti vi sinh vt phn h a . Nc thi t qu trnh ny rt giu cht

di dng thc vt c t h c, it, p t pho, kali, st v canxi. Khi lng

ln cht thi t a c th c ti ch tr li lm phn h c.

27

T c a l p n cn li sau khi tch si, trong khi si a c i tr

t mi ln th ph t a c coi l mt cht thi nng nghip. T l khi

lng ca g t a so vi si l 2,5:1. G t a c im khong 40% ca tng

khi l c a . c tnh mi m lng cht thi th a ca khong

4 triu tn v Bangladesh l khong 3 triu tn.

T a c a m lng cellulose, hemicellulose v lignin cao l lt l

40, 35 v 23%. V vy, n l mt ngun nguyn liu tim sn xut bt giy.

T a l mt trong nhng nguyn liu lignocellulose thay th cc nguyn liu

truyn thng trong sn xut bt giy Ba lades . c cc i cu tn dng

t a l m t a ci cho nhiu ngnh cng nghip, sn xut cc ha cht v cc

nhin liu lng. Tuy nhin, phn ln th a c s dng lm nhiu liu v lm

hng ro nng thn. Kho 80% t a c s dng lm nhin li

nu ti cc h ia nng thn, ch yu v Bangladesh. Vit Nam,

t a sa k i tc si t ng b thi b, s t c dng lm cht t, hng ro.

1.5. Tim nng s dng ph phm cy ay lm vt liu x l nhim mi

trng

Trong nh m , vic s dng vt liu l cht thi nng nghip

hoc nhng vt thc vt t c gi tr kinh t c c bit quan tm. Nhiu nghin

c c tin hnh nhm bi i cc cht thi nng nghip thnh vt liu x l

mi trng.

Si c a l si cellulose t nhin ph bin trn th gii; c bit, do tnh

cht vt l, ha hc v cu trc tt. c rt nhiu nghin cu bin tnh si c a

thnh vt liu x l c nhim mu, kim loi nng. Tuy nhin, ph ph phm

ca qu trnh tr a v sn xut si a li l mt v mi tr . c tnh,

mi m t tr a to ra 5 - 10 tn tr lng kh bao gm c si v thn cy.

Khong 1 tn cht k c tr li t dng l, khong 3 tn r v c tro t

[46]. Lng cht thi rn t qu trnh sn xut a l k, bao gm cc si a

28

h , l v t c a . Do , p t trin mt chi lc qun l hiu qu cc cht

thi p t si l iu cn thit.

T c a l mt vt liu lignocellulose, do , c t ti ch thnh vt

liu trong x l c thi, loi b kim loi nng, mu v cc cht h c. Tuy

nhin, nghin cu v s dng cht thi t a mt cht hp ph cn hn ch,

c bit l ng d t a x l kim loi n tro c.

Kh hp ph thuc nhum ca t a c c nghin cu [46].

Than hot t c iu ch t t a c k p ph mu tt. T a

loi b c ti a 81,7% xanh methylen so vi 61% khi s dng than hot tnh

dng bt v 40% khi s dng than hot tnh dng vin. Tuy nhin, hiu qu loi b

BOD (33,3%) v COD (13,8%) l thp so vi x l bng than hot tnh dng

vin.

Bt t a c chng minh l mt vt liu c c kh x l phm

mu c v Rhodamin B tro c [21]. Qu trnh hp ph xy ra khi pH

khong 7 v nhit khng ng nhi n kh p ph. D lng

hp ph ti a ca bt t a i vi c l 35,7 m / v i vi

Rhodamine B l 87,7 mg/g. Hp ph x ra a v t trng thi cn bng ban

u trong vng 60 pht. Bt t a c c nghin c x l phenol trong

c [9]. Vi n p e ol ba u l 40 ppm trong 100 mL, pH dung dch bng

10; 3 a x l c 68% phenol.

nng cao kh p ph, bt t a c nghin cu ch to thnh

than hot tnh [37]. Ch to than hot tnh t t a bng cch s dng hai

p p p vt l v ha hc. T a c hot ha bng ZnCl2 t eo p

php ha hc v i c t eo p p p vt l loi b thuc nhum Brilliant

Gree tro c. Din tch b mt ca than hot t iu ch b p p p

ha hc l 2.304 m2/ v p p p vt l l 730 m

2/ . D lng hp ph cc

i ca than hot t iu ch b p p p a c l 480 m / v p

php vt l l 182 mg/g. Than hot tnh t t a c hot ha bng axit H3PO4

29

x l As (III) v As (IV) tro c [26]. Din tch b mt ca than hot tnh l

1.910 m2/ v d lng hp ph cc i l 399 mg/g.

P p p bi t ng trng hp ghp nhm amidoxime c chng

mi l p p p ph hp bin tnh vt li c m lng cellulose ln v

hiu qu x l kim loi n tro c cao. Tuy nhin, hin nay, cc cng trnh

nghin cu bi t t a b p p p ng trng hp p x l kim

loi nng cn rt t.

30

Chng 2 - I V PH PHP HI CU

2.1. i tng nghin cu

T c a sa k i tch si c thu thp ti x Nam Thng, huyn Tin

Hi, tnh Thi Bnh. Thn cy a c ra sch vi c ct, sy kh 105C v

nghin thnh dng bt kc t c < 0,5 mm, c bo qun trong hp plastic.

Cc m c nhn to cha c lp cc ion kim loi nng (Zn2+

, Ni2+

, Cu2+

)

cc n k c a c pha long t dung dch gc chun c n 1000

mg/L.

2.2. Phng php nghin cu

2.2.1. Phng php bin tnh vt liu

2.2.1.1. X l b d dc NaOH

T a c ra ba ln vi c ct, s k n khi l k i

sau c nghin thnh dng bt kc t c < 0,5 mm. Sn phm t c

c bo qun trong hp plastic. Bt a c x l bng dung dch NaOH (5-

25%) vi t l bt a /d dch l 1/50 (g/mL), trong 60 pht 25C, lc vi tc

150 vng/pht. Sau khi x l bng dung dch NaOH, m c lc loi b

NaOH d v ra vi c ct n pH trung tnh. Phn cht r t c tip tc

c sy 60C k i l k i. N NaOH x l tt t c

i t q a m l v c s ti t ca cellulose tro bt t a

sa x l.

c i x c tr ca cellulose I l (101), (101-), (002) cc v tr

14,6 , 16,1 v 22,5 (2); xelulozo II l (101), (101-), (002) cc v tr 12 , 20 ,

22 (2) [16] (Hnh 13). V tr cc i x c t dao k i

q a i tr c 2.

31

Hnh 13. V tr cc nh nhiu x c trng ca cellulose I (a) v cellulose II (b)

trong ph nhiu x tia X

T eo p p p Se al [45], c s ti t ( rI) c t t eo c t c

1 (vi cellulose I) v c t c 2 (khi cellulose I c sa d cellulose II).

CrI = ((I002 Iam)/I002) x 100 (1)

CrI = ((I101- - Iam)/I101-) x 100 (2)

Tro , I002 l c ti a ca ti t i x (002) i vi

cellulose I, I101- l c ti a i x (101

-) i vi cellulose II. Iam l

c t p t m ia 2 i x (002) v (101-) i vi cellulose I;

ia 2 i x (101-) v (101) i vi cellulose II. Iam l c v tr 2

= 18.0 vi cellulose I v 2 = 16.0 i vi cellulose II.

32

2.2.1.2. tr p ghp acrylonitrile ln bt thn a

Bt t a sa k i bi t b NaOH c tr p p

acrylonitrile (AN) ln cellulose. Ly 1 g bt a x l NaOH vo bnh c

trn lp si i l . Tip t eo, 100 mL c t k i m o NaHSO3/(NH4)2S2O8

c b sung vo bnh, sc kh N2 v k tro 30 p t. P c i

c it 40 - 70C b m k t ia it. Sa t m AN, k

vi tc 300 v/p trong t i ia 120 - 210 pht. P tr p c

kt t c b cc c o k k v o b p v l m l b . Thm vo

bnh 100 mL d dc eta ol loi b AN d, t i kt ta s p m, loi

b cc m i; p c t r c lc q a i lc, sa ra li b etanol v

c ct (3 l ). S p m c s k 60C k i l k i. S

p m bao m polyme ca AN (polyacrylonitrile) v bt t a p AN.

S p m p c ra v i l vi N,N-dimetylfocmamit loi b

polyacrylonitrile. t r t c sa k i lc c l m k k i l k

i v i li k i l s p m.

Cc yu t n phn ng trng hp ghp AN ln bt a

c kho st bao gm: n cht k i m o, t l khi l AN/t a , it

v thi gian phn ng. ng ca cc iu ki c i t q a t

l ghp v hiu sut ghp, t tm ra iu kin ti c o mi yu t.

T l ghp (%G), hiu sut p (%E) c tnh theo cc cng thc 3 v 4

[15].

T l ghp (%G) = [(W1 W0)/W0] x 100% (3)

Hiu sut ghp (%E) = [(W1 W0)/W2] x 100% (4)

Tro , W0, W1 l lt l khi lng ca bt a c a p v sa k i

ghp AN. W2 l khi l AN ba u.

33

Cc th nghim kho st cc yu t n kh p

acrylonitrile ln bt t a c ti c lp, c tnh k tha (kt qu ca

th nghim trc l iu ki thc hin th nghim sau) v th hin trong bng 5.

Bng 5. nh hng ca cc iu kin phn ng n kh nng ghp AN ln bt thn ay

TT Th nghim B tr th nghim

1

ng t l

[SB/APS]

(CM/CM)

mbt t a = 1 g, Vt = 100 mL, [APS] = 0,2 mol/L,

2h, 60C, VAN = 5 mL (99,9%),

[SB] = 0; 0,05; 0,1; 0,15 hoc 0,2 mol/L

2

ng ca nng

h k i m o [I],

[I] = [SB] + [APS]

mbt t a = 1 g, Vt = 100 mL, 2h, 60C, VAN = 5 mL

[I] = 0,035; 0,0875; 0,175; 0,35; 0,525 hoc 0,7

mol/L

3 ng ca t l

AN/a


[SB] = 0,15 mol/L, 2h, 60C,

A /ay (g/g) = 1,62; 3,24; 4,05; 4,86; 6,48 hoc 8,1

4 ng ca thi

gian phn ng


[SB] = 0,15 mol/L, 60 , AN/a = 4,86 (t

vi 6 ml AN);

hi gian = 2; 2,5; 3 hoc 3,5 gi

5 ng ca nhit

phn ng


[SB] = 0,15 mol/L, 2,5 i; VAN = 6 mL;

AN/a = 4,86;

T = 40, 50, 60 hoc 70C

Ch thch: SB l natri bisunphit, APS l amoni pesunphat, Vt l tng th tch

(mL), AN l acrylonitrile, VAN l th tch acrylonitrile (mL), I l h k i m o

SB/APS.

34

2.2.1.3. Amidoxime a s p m p acr lonitrile

1 g c t r t c sau khi ghp acrylonitrile c amidoxime a b

NH2OH.HCl (2,5 - 15%) trong p dung dc met a ol : c (v : v = 1 : 1)

sao c o t t tc d dc b 50 ml. pH ca d dc c i c

k o t 9 10 b m i Na2CO3. P it 25 - 80C trong t i

gian 30 - 360 pht, k vi tc 300 v/p. Sa p , lc q a i lc loi

b p d dc v ra s p m t c 3 l vi c ct pH tr t ,

s k k i l k i.

Cc yu t n phn ng amidoxime ha sn phm ghp PAN

bao gm: n NH2OH.HCl, nhit phn ng, thi gian phn ng. Da vo

m lng t it i iu qu ca qu trnh amidoxime [11]. S bin

thin ca m lng t it biu th cho s t a i ca nhm amidoxime trong

vt liu.

nh hng ca nng NH2OH.HCl: 1 g sn phm p c phn ng

vi dung dch NH2OH.HCl cc n khc nhau (2,5; 5; 7,5; 10; 12,5 hoc 15

%) 25C trong 120 pht. Sa p , li tm tc p c t r , ra li b

c ct pH tr t , s k k i l k i v xc m

l ito.

nh hng ca nhit phn ng: 1 s p m p c p vi

d dc NH2OH.HCl n ti xc nh th nghim trc, trong khong

thi gian 120 pht. Nhit phn t a i 25, 30, 40, 50, 60, 70 hoc 80C.

nh hng ca thi gian phn ng: 1 s p m p c tip xc vi

d dc NH2OH.HCl n ti v nhit ti hai th nghim trc.

Thi gian phn t a i t 30, 60, 120, 180, 240, 300 hoc 360 pht.

2.2.2. Xc nh c tnh c bn ca vt liu

Vt liu hp ph c xc c im vt l v ha hc c bn, chi tit

cc p p p c trnh by trong bng 6.

35

Bng 6. Phng php xc nh mt s tnh cht vt l, ha hc ca vt liu

Tnh cht Phng php phn tch Thit b phn tch

c im hnh thi Knh hi vi in t qut JSM 5410LV, hng Joel

c im cu trc Nhiu x tia X Bruker-AXS D5005,

Sieme s, c

in tch b mt P tc in di Mtek PCD 05, hng

BTG, c

c im lin kt,

nhm chc

Quang ph hp th hng

ngoi (FTIR)

Nicolet iS5 FTIR

Spectrometer, hng

Thermo Scientific, M

- Phng php nh lng cellulose [1]

P p p lng cellulose da trn tnh cht bn ca cellulose i

vi tc dng ca axit mnh v kim mnh, khng b phn h di tc dng ca

axit yu. Cc cht khc c trong vt liu ligniocellulose hemicellulose, lignin,

tinh bt, amin, cc axit bo,... t bn trong dung dch axit v kim nn b oxi ha v

phn gii, sa ta v o d dch sau khi x l nguyn liu.

P p p lng cellulose c ti sa : c xc 1-

2 am t a k c o v o b tam ic 500 mL, b sung vo bnh 200 mL dung

dch NaOH 0,5%. Lp si o l tro 30 p t k t lc si. Lc

cht rn qua giy lc hoc ly tm. Ra cht r t c vi dung dch NaOH 0,5%

nng. Tip tc cho cn tc dng vi 10 mL H l 10%. T m v o 10 mL d

dch natri hypoclorit tng git mt, va cho va khu . yn trong 5 pht ri

lc qua giy lc thu cht rn. Cho cht rn tip tc tc dng vi NaOH 0,5%

nhit 40o . yn vi pht v lc cht rn. Lm lp li 2 ln na t c

cellulose trng. Sau cng, ra sch cellulose t c b c si. Sy kh v

cn tr lng cellulose.

36

H m lng cellulose trong t a c tnh theo cng thc:

X (%) = (a.100)/m (5)

Tro : a l tr lng cellulose (g)

m l tr lng m t a ( )

2.2.3. Kho st kh nng hp ph ion kim loi nng ca vt liu bin tnh

- nh hng ca pH: xc thng qua bi i m i b mt ca vt

li sa k i bi t ti cc i tr pH k c a . Gi tr pH t c p p i t p

i tr pH kt ta cc cc io kim loi v t im axit t si tro

c sa k i x l.

- Xc nh cc h s hp ph ca vt liu bin tnh vi cc ion KLN

Ti t im p p cc io kim loi Cu2+

, Zn2+

hoc Ni2+

b 100 m vt li bi t trong 100 mL dun dc c a cc io kim loi vi

ba l 0, 20, 40, 60, 80 oc 100 m /L. T im c ti

25C, pH d dc b 6 (pH k o st c tro t im trc), lc vi tc

100 v /p t tro v 1 i v m 24 i. c lc xc

io kim loi c li tro d dc sa c b p p b m q ang

p p t t AAS (S imadz , N t B ).

- Xc nh thi gian lu ti u cho qu trnh x l ion KLN (Zn2+, Ni2+,

Cu2+

) vi vt liu bin tnh

Cn 250 mg vt liu vo 250 mL dung dch cha Zn2+

, Ni2+

hoc Cu2+

c

n (Qimax x 250mg) / 250mL = Q

imax (mg/L) vi Q

imax (m / ) l d lng

hp ph cc i ca vt liu vi Zn2+

, Ni2+

hoc Cu2+

. M c lc tc 100

v/p theo thi gian. Sau mi khong thi gian cch nhau 1 gi, dung dch cha vt

li c lc u v ly ra 25 mL sao cho mt vt liu tromg dung dch cn li

v ly ra l bng nhau. Dung dch l ra c lc v phn tch KLN bng my

quang ph hp th nguyn t AAS (S imadz , N t B ).

37

Chng 3 - K QU HI CU V HO LU

3.1. c tnh c bn ca bt thn ay

Bt t a l vt liu lignocellulose, cha mt m lng cellulose

k. Cellulose trong bt t a l c i polyme chnh, nhm (-OH) trn phn t

cellulose vai tr q a trng trong lin kt vi nhm nitrile ca monome

acrylonitrile ln bt t a . Do , cc c t c bn ca t a bao m c

im hnh thi b mt, cu trc cellulose, cc nhm chc b mt trn bt t a

c c kho st trc khi tin hnh bin tnh ha hc.

3.1.1. c im hnh thi b mt ca bt thn ay

Bt t a c d v kc t c k ng nht. Kt qu phn tch

trn knh hi vi in t qut (SEM) cho thy dy cc mnh bt t a khong

5 m. B mt ca bt t a ba u c cc mng bm nh dng vy (Hnh 14).

i t t khi quan st thy trong bt g ca cc sinh khi khc [32].

(a) nh chp p i 1000 ln (b) nh chp p i 2500 ln

Hnh 14. nh SEM b mt bt thn ay

38

3.1.2. c im cu trc ca bt thn ay

Thnh phn ca bt t a bao m c vng v nh hnh v vng tinh

th. Tro lignin, hemicellulose, pectin l nhng hp cht v nh hnh ch yu;

tro k i cellulose ng thi tn ti c hai d v nh hnh v tinh th. Dng

v nh hnh trong cellulose khi dng sinh khi ba u l dng tinh th cellulose

I [48, 50]. Kt qu nhiu x tia X (Hnh 15) cho thy kt qu t ng vi cc

nghin cu v cc sinh khi thc vt khc. c nh nhiu x c tr ca dng

cellulose I xut hin v tr c 2 l 22,52o

(002); 16,01 (101-) v 15,11 (101). Ch

s tinh th ca cellulose trong bt t a c i tr l 55,76 %. N v , mt

na lng cellulose tro t a tn ti dng tinh th. Tro k i , p

php bin tnh ha hc c hiu qu i vi v v nh hnh v d tip c

so vi vng tinh th. Do , bt t a cn phi x l ph v cu trc tinh th,

t t l v v nh hnh.

Hnh 15. Ph nhiu x tia X ca bt thn ay

39

3.1.3. c im lin kt, nhm chc

Kt qu phn tch ph hp th hng ngoi i vi bt t a cho thy, b

mt ca bt t a cho thy bao gm cc nhm v lin kt ch yu l (OH),

C=O, C=C, CC, CH. Cc nh hp th s sng 3.350 cm-1

biu th dao ng

ca nhm (OH). Nhm ny c th tn ti trong lin kt (OH) lin phn t, ni

phn t ca cellulose, hemicellulose, lignin; lin kt hydro trong nhm cacboxyl.

Tro k i , nh hp th s sng 1.739 cm-1

th hin s tn ti ca lin kt C=O

trong nhm cacboxyl. Lin kt CO ti v tr v t m ca lignin xut hin s

sng 1.250 cm-1

. Vch ph s sng xut hin s sng 1.598 cm-1

th hin dao

ng dn ca lin kt C=C trong cc axit bo.

Hnh 16. Ph hp th hng ngoi ca bt thn ay

Nhn chung, qua ph hp th hng ngoi c th thy, b mt ca bt t a

cha cc nhm chc in hnh l nhm hydroxyl, nhm cacboxyl. Cc nhm chc

ny c vai tr quan tr tro p p p bi t ng trng hp ghp, trong

c bit quan trng l nhm hydroxyl trong polyme cellulose.

40

3.2. Quy trnh bin tnh to vt liu amidoxime ha t bt thn ay

3.2.1. X l bng dung dch NaOH

3.2.1.1. Lm giu cellulose trong bt t a

X l bt t ay bng dung dch NaOH nhm loi b cc cht h c d b

thy phn, c th to thnh cc cht h c tro c l lignin, hemicellulose,

amin, axit h c. Bt t a sa x l c m lng cellulose-polyme mch

chnh t , ip c o phn ng trng hp ghp vi AN c thun li.

ng ca n dung dch NaOH x l n khi lng bt t a

a c li v s bi i m lng cellulose trong bt t a c th hin trn

hnh 17.

Hnh 17. nh hng ca nng NaOH n khi lng cn li v hm lng

cellulose trong bt thn ay

K i t NaOH, qu trnh thy phn cc cht lignin, hemicellulose,

axit bo,... din ra cng mnh nn khi l a c li gim. iu ny d n

m lng cellulose trong bt t a c t k i t NaOH. Khi

lng bt t a c li gim nhanh khi n NaOH t n 5 v 10% so vi

bt t a ba u do qu trnh ha tan ph v nh hnh din ra mnh. Tuy

41

nhin, khi tip tc t NaOH th khi lng bt t a im khng

nhiu v g do m lng ph v nh hnh trong bt t a l

gii hn.

Qu trnh x l bng NaOH thc cht l qu trnh lm giu cellulose lm

nguyn liu cho cc bc nghin cu bin tnh tip theo. khong n NaOH

t 10% tr ln, m lng cellulose t mc cao v g nh.

3.2.1.2. Xc nh ch s tinh th ca cellulose trong bt t a bng ph nhiu x

tia X

Qu trnh x l b NaOH ng thi l m t a i cu trc ca cellulose

trong bt th a . P nhiu x tia X ca bt t a t v bt t a x l

bng dung dch NaOH cc n k c a c th hin trn hnh 18.

Hnh 18. Ph nhiu x tia X ca bt thn ay ban u v x l cc nng dung

dch NaOH khc nhau

C th thy rng, bt t a ba u C0 v bt t a c x l vi

dung dch NaOH cc n 5% v 10% l C5 v C10 dng cellulose I vi cc

nh nhiu x v tr c 2 l kho 22,5 n 22,7 v cc nh nhiu x v tr

42

14 n 16. Khi n NaOH t n 15%, xut hi ai nh nh nhiu x

v tr c 2 l 20,1 v 12,2. l cc nh nh nhiu x c tr ca cellulose

II. iu ny chng t rng qu trnh x l bng dung dch NaOH lm chuyn dang

cu trc ca cellulose I sang cellulose II. Cc nh nhiu x c tr ca cellulose

II c x t hin cc m a x l vi dung dch NaOH 20 v 25% (C20 v

C25).

Ch s tinh th c tnh ton theo cng thc v 1 v 2 (mc 2.2.1.1), s ph

thuc ca ch s tinh th vo n NaOH c th hin trn hnh 19.

Hnh 19. S bin i ch s tinh th ca cellulose trong bt thn ay khi x l vi

dung dch NaOH cc nng khc nhau

Ch s tinh th ca bt t a t l 16,72% so vi th a ba u sau

khi x l vi NaOH 5%. Tuy nhin, khi n NaOH t l t c s tinh th

li gim d v t gi tr ti thiu 45,45% ti n NaOH l 15%. Sa , c

s tinh th t khi n NaOH t l 20% v t gi tr nh. iu

ny c th gii thch do ba qu trnh xy ra khi x l bng kim: bt t a tr

n, ph v vng tinh th v hnh thnh mng tinh th mi. n NaOH thp,

lng NaOH v mt NaOH nh, k ph v mng tinh th cellulose vi

cu trc c bao bc bi hemicellulose v lignin. Ch c v v nh hnh v

43

vng tinh th b mt trong cu trc cellulose c th phn ng vi kim. N vy,

vng khng gian gia cc mch polyme cellulose khng ln nn cc si c kh

sp xp li cu trc [48]. Do , c s tinh th ca t a t k i

NaOH nh. K i t NaOH ln 15%, cu trc cellulose t trng thi

tr nhiu nht, iu ny lm cho NaOH d dng tip xc vi cc vng tinh

th ca cellulose v ph v cu trc tinh th d n CrI gim k. Tuy nhin,

kh tip xc vi cellulose ca NaOH gim do t nht ca dung dch

NaOH n cao [48], do , c s tinh th vn ln.

T cc kt qu thc nghim nu trn, c th thy rng n NaOH 15% l

n thch hp nht lm gim cc vng kt tinh trn cellulose c l m

t m lng cellulose trong bt t a .

3.2.1.3. c im lin kt v nhm chc b mt

Ph hp th hng ngoi ca bt t a t v sa k i x l bng NaOH

cc n khc a c th hin trn hnh 20.

Hnh 20. Ph hp th hng ngoi ca bt thn ay ban u v x l cc nng

NaOH khc nhau

44

Kt qu cho thy, lin kt hydro trong nhm hydroxyl (OH) dao ng xut

hin di ph t 3.000 - 3.600 cm-1. nh hp th ca nhm (OH) gim dn khi

n NaOH t l do m OH p n ng vi Na+. S suy gim nhm (OH)

c th do qu trnh thy phn cc cht km b axit bo, emicell lose, li i

trn b mt bt t a . c li kt hydro ni phn t O2-H---O6, O3-H---O5 v

lin kt hydro lin phn t O6-H---O3 tro cell lose I t ng xut hin di ph

t ng l 3.455 - 3.410, 3.375 - 3.340 v 3.310 - 3.230 cm-1

. Ph hp th hng

ngoi ca bt t a ba u v x l cc n dung dch NaOH thp (5, 10

%), nhm (OH) xut hin s sng 3.350 cm-1

; tuy nhin, khi x l cc n

NaOH cao (15, 20, 25%), nhm OH xut hin s sng 3.447 cm-1 c tr c o

lin kt O2-H---O6 tro cell lose II. iu ny chng t rng, cu trc tinh th ca

cell lose I c n sang dng cellulose II sau khi x l bng NaOH.

nh hp th s sng 1.739 cm-1

quan st thy trong bt t a ba u

v mt i sa k i x l bng kim tt c cc n NaOH trong nghin cu.

iu ny l do nhm cacboxyl b thy phn sau khi x l bng kim, qu trnh ny

c gi l este ha [32]. S suy gim c ca nhm C=O s sng 1.655

cm-1

khi x l bng kim ch ra rng hemicellulose b loi b sau khi x l kim.

nh hp th v tr s sng 1.250 cm-1

hin th cho lin kt C-O ti v tr

v t m ca lignin trong bt t a c im i k sau khi x l bng

kim. nh hp th v tr 897 cm-1

chuyn sang v tr 894 cm-1

. S sng 897 cm-1

trong lin kt -glucozit trong cu trc cellulose I v s sng 894 cm-1

trong cu

trc cellulose II [50]. S t a i ny l do glucose quay quanh lin kt glucosidic

lm cho cu trc cellulose I chuyn sang dng II.

45

3.2.2. ng trng hp ghp acrylonitrile ln bt thn ay bng h khi mo natri

bisunphit/amoni pesunphat (SB/APS)

3.2.2.1. c ca p tr p p acr lonitrile b k i m o

natri bisunphit/amoni pesunphat

Phn ng trng hp ghp AN bng h k i m o oxi a k SB/APS

da tr c c gc t do. Gc t do c to thnh t phn ng ca h k i m o,

sa cc gc ny tip tc phn ng vi nhm OH trn mch cellulose hnh

thnh cc gc cao phn t. Cc gc cao phn t ny tip tc khi xng phn ng

ng trng hp ghp AN ln mch cellulose. Phn ng trng hp polyacrylonitrile

(PAN) c di ra ng thi vi phn ng trng hp ghp.

Gc t do SO4-*

c to ra t phn ng gia natri bisunphat v amoni

pesunphat t eo p tr 7 [43].

H2O + HSO3- + 2S2O8

2- 3HSO4

- + 2SO4

-* (7)

SO4-*

+ H2O HSO4- + HO

* (8)

Gc SO4-*

s tip tc phn ng vi cc nhm hydroxyl trn mch cellulose

[40] hnh thnh cc gc cao phn t trn cellulose (Cell OH) (p tr 9)

v gc t do M* (p tr 10).

SO4-*

+ Cell OH HSO4- + Cell O

* (9)

M + SO4-*

M* + SO4

2- (10)

Cc gc cao phn t ny tip tc khi xng phn ng ng trng hp ghp

monome ln mch cellulose v phn t PAN t eo c c sau:

Cell O* + M Cell OM

* (11)

Cell OM* + M Cell OMM

* (12)

Cell OM*n-1 + M Cell OMn

* (13)

Cell OM*n + Cell OM

*n sn phm ghp (14)

46

Phn ng trng hp PAN din ra song song vi phn ng trng hp

p, c c phn ng trng hp AN sa :

M* + M MM

* (15)

Mn-1* + M Mn

* (16)

Mn* + Cell-OH Cell-O

* + MnH (17)

Mn* + Mm

* Mn+m (18)

P p p ng trng hp ghp c k i m o bng h oxi ha kh, cc

gc t do phn c to ra t phn ng ha hc. Do , cc u t n

cht k i m o, monome, thi gian, nhit l nhng yu t ng

trc tip n hiu sut qu trnh ghp.

3.2.2.2. ng ca t l cc cht k i m o

Hnh 21 th hin ng ca t l cc cht k i m o SB/APS (CM/CM)

n t l ghp v hiu sut ghp. N SB t a i t 0 n 0,2 mol/L, n

APS c nh n 0,2 mol/L. Kt qu cho thy, t l ghp (G%) t cao nht l

13,13% v hiu sut p t 3,24% khi t l SB/APS l 0,75.

Hnh 21. nh hng ca t l SB/APS n kh nng ghp AN ln bt thn ay

47

t l thp , SB k phn ng vi APS to thnh gc

t do d n t l ghp v hiu sut ghp thp. T l ghp t l k iu

k i t SB. T l ghp t 2,51% khi h k i m o ch c APS v t l

t 2,55% khi t l SB/APS l 0,25. iu ny chng t rng; khi n SB thp,

phn k i m o c y do APS vai tr c . K i c cung cp nhit

, ion pesunphat trong APS c th to thnh gc t do t eo p tr sa :

S2O82-

2SO4-*

(19)

SO4-*

+ H2O HSO4- + HO

* (20)

Khi t l SB/APS t l 0,5 p n k i m o to thnh nhiu gc t do

d n t l ghp t l 3,83% v t gi tr cao nht l 13,13% khi t l ny

l 0,75. T eo p tr 7, t l cn bng ha hc ca phn ng to gc t do

gia SB v APS l 0,5.

T l SB/APS tip tc t l 1 t G (%) v E (%) im do cc gc t do

to thnh t phn ng k i m o to ra ln d n phn ng trng hp PAN cnh

tranh vi phn ng trng hp ghp, cc gc t do M* ca AN phn ng vi

nhau lm gim hiu qu phn ng ghp. Trong phn ng ghp nhm vinyl ln

g/cellulose, HO* c kh p n i SO4

-*. Tuy nhin, khi t l SB/APS

cao, gc t do b trit ti t eo cc p tr (21) (23) [43].

SO4-*

+ H2O HSO4- + HO

* (21)

2SO4-*

+ HSO3- 2HSO4

- + SO4

2- + H

+ (22)

2HO* + HSO3

- SO4

2- + H2O + H

+ (23)

3.2.2.3. ca k i m o SB/APS

T l SB/APS = 0,75 c la ch nghin cu ng ca tng nng

h k i m o n kh p. Tng n h k i m o [I] = [SB] + [APS].

Hnh 22 th hin s ph thuc ca t l ghp v hiu sut ghp vo n h k i

mo I. iu ny ph hp vi l thuyt Smith-Ewart d o rng tc ca phn

48

ng trng hp ph thuc vo hai bin, n k i m o v cht c hot

b mt.

Hnh 22. nh hng ca tng nng h khi mo n kh nng ghp ca AN ln

bt thn ay

Ba , k i t h k i m o, t l ghp v hiu sut p t ,

sa im dn. Kh p tt nht t c khi tng n k i m o l

0,35 mol/L vi t l ghp l 13,13% v hiu sut ghp l 3,24%. S ia t ca t

l ghp v hiu sut ghp l cc gc t do c to t t k i h k i

m o t v cc c ny c s phn ng vi mch cellulose. Khi n h

k i m o t 0,35 mol/L, cc gc t do pesunphat t l ; do ,

khi xng phn ng trng hp AN, phn ng ny cnh tranh vi phn ng

trng hp ghp do cng tiu th AN v gc pesunphat.

3.2.2.4. ca t l acrylonitrile/a

T l khi l AN/a l yu t quan trng quyt nh hiu qu qu trnh

ghp. ng ca t l AN/a c th hin trn hnh 23.

49

Hnh 23. nh hng ca t l khi lng AN/ay n kh nng ghp AN ln bt

thn ay

K i t t l khi lng AN/a t 1,62 (t ng vi 2 mL c) ln 4,05

(t ng vi 5 mL AN c) th t l ghp t t 3,59 n 13,13%. Hiu sut

ghp c s t a i k k. Khi t l AN/a t l n 4,86 (t ng

vi 6 mL AN c) th kh p t l rt nhanh, t l ghp t cao nht l

88,63% v hiu sut ghp l 18,24%. iu ny l do lng AN t l m t kh

tip xc ca AN vo mch cellulose tr t a , d t k p

AN vo cc gc t do trn mch cellulose. H a, n AN cao cn lm cho

bt t a tr , to iu kin cho s khuc t cc mo ome AN do l m

t iu qu ghp [17]. Tuy nhin, t l ghp v hiu sut ghp li c x ng

gim nhanh khi tip tc t t l AN/a q 4,86. i c gii thch l do

s cnh tranh gia phn ng trng hp AN v phn ng trng hp ghp. Khi

n AN trong dung dch phn ng cao th phn ng trng hp AN chim t

[30].

50

3.2.2.5. ca t i ia p

Kt qu ng ca thi ia n kh p c th hin trn hnh

24. C th thy, kh p t a k i t i gian phn t t 2 n

2,5h; t gi tr t l ghp v hiu sut ghp ti a l lt l 131,36% v 27,03%

2,5h. Tuy nhin, sau 2,5h th kh p c x im c th l do s ha

tan mt phn sn phm ghp khi tip xc trong thi gian di nhit cao 60C [17].

Do , t i gian phn hiu qu ghp ti l 2,5 .

Hnh 24. nh hng ca thi gian phn ng n kh nng ghp AN ln bt thn ay

3.2.2.6. ca it p

Nhit l mt trong nhng thng s quan trng quyt ng hc ca

qu trnh ghp. Kt qu cho thy, t l ghp v hiu sut p t k i t it

t 40 60 , sa im dn khi nhit t l n 70C. T l ghp v hiu

sut ghp cao nht t c khi nhit phn ng 60C l lt bng 131,36% v

27,03%. N vy, nhit ti c o p n p AN l t a l 60 .

Nhit cao l m t k va c m ca cc phn t v cellulose d n s

51

gia t cc c t do tr cell lose v do t cng kh p AN l

cellulose. Mt khc, hiu sut ca phn k i m o t l k i t it .

Hnh 25. nh hng ca nhit n kh nng ghp AN ln bt thn ay

Tuy nhin, t l ghp v hiu sut ghp li gim nu tip tc t it

ln 70C c th do phn k i m o si ra mt lng ln cc gc t do trong

mt v thi gian. Kt qu l, cc gc t do trn b mt cellulose d tip xc vi

nhau lm mt cc gc t do theo cc phn ng ngt mch. Mt khc, khi nhit

t , li ng ca cc gc t do s t v d dng tip xc vi nhau [40]. Xu

c c quan st thy trong cc nghin c t t [17,29]. Mt

nghin cu c cng b [43] tin hnh kho st ng thi t l ghp v hiu

sut hnh thnh PAN, kt qu ch ra rng, nhit 40-60C, phn ng trng

hp ghp chim t . Tuy nhin, nhit cao (70 ) t p n ng trng

hp AN li chim t . Do , it ti ca phn ng trng hp ghp

AN ln bt t a l 60 .

52

N vy, hiu qu ca phn ng trng hp p AN l t a cao

nht khi: n natri bisunphit, 0,15 mol/L; n amoni pesunphat, 0,2 mol/L;

t l khi lng AN/bt t a , 4,86:1 g/g; thi gian, 2,5h; nhit , 60C.

3.2.3. Phn ng amidoxime ho

3.2.3.1. ca NH2OH.HCl

Sau phn ng trng hp ghp AN ln bt t a , m l it (%)

t t 0,18% trong bt t a c a bi t l n 3,18%. Sn phm ng

trng hp p c tip tc phn ng amidoxime vi hydroxylamin

hydroclorid cc n khc nhau. Khi n NH2OH.H l t trong khong

t 2,5 n 10%, m l it tro vt li t l k chng t m lng

nhm amidoxime trong vt li t l . iu ny l do cc nhm nitrile (CN)

trn b mt vt liu c s phn ng vi NH2OH tro mi trng kim to

thnh nhm amidoxime (C(NH2)=NOH).

Hnh 26. nh hng ca nng NH2OH.HCl

K i t n NH2OH.H l t l t 10 15% t m l it

t k k; t 8,35% 10%, 8,43% 12,5% v 8,54% 15%. N vy,

53

n NH2OH.HCl 10% l n m phn ng to thnh nhm amidoxime t

trng thi . Do , c chn thc hin cc th nghim tip

theo.

3.2.3.2. ca it p

Hnh 27. nh hng ca nhit phn ng

ng ca nhit n kh amidoxime a c th hin trn

hnh 27. Kt qu cho th , m lng nit t a k i it phn t

trong khong t 25 l 60 v t ti a l 10,47% 60C, chng t m lng

nhm amidoxime trong vt li t a k i it t . T i , k i

nhit l cao l 60 t m l it li gim. iu ny c th do nhit

cao lm phn ly cc nhm nitrile trn b mt bt t a , d n lm gim v

tr hot ng ca phn ng chuy i. X t t c c quan st thy

trong nghin cu ca c cng b [20].

54

3.2.3.3. ca t i ia p

Thi gian phn ng amidoxime c t a i t 30 n 360 pht v gi cc

thng s nhit c nh 60C v n NH2OH.HCl l 10% i nh

ng ca thi ia n phn ng chuyn ha nhm nitrile thnh nhm amidoxime.

Hnh 28. nh hng ca thi gian phn ng

Kt qu nghin cu cho th , m l it c m lng nhm

amidoxime trong vt li t a k i t i gian phn t n 120 pht. Khi

tip tc t t i gian ln 180 v 240 pht t m l it t c m v t n

nh khi thi gian phn l 240 p t. Lng amidoxime c to thnh ln

tro iai o u ca phn ng l do s lng nhm nitrile c sn trn b mt

t a c o c chuyn ha thnh amidoxime. N k i t g thi gian phn

ng, s lng cc nhm nitrile im rt nhiu d n hiu sut phn ng thay

i khng nhi . N vy, thi gian bo ha ca phn ng amidoxime l 240 pht.

T cc kt qu ti a cc bc tro p p p bin tnh to vt liu

amidoxime ha t bt t a , s quy trnh bin tnh vt li c th hin trn

hnh 29.

55

R/L = 1: 50 (g/mL)

- R/L = 1:50 (g/mL)

- pH = 9 10

T l AN/a = 4,86

(g/g)

R/L = 1: 100

(g/mL)

Bt t a

NaOH 15% - Thi gian: 1 gi

- Tc lc: 150 v/p

- Lc, ra sc n pH = 7

Bt t a x l NaOH Hn hp

NaHSO3/(NH4)2S2O8

[NaHSO3] = 0,15 mol/L

[(NH4)2S2O8] = 0,2 mol/L

- Sc kh N2

- Nhit 60C

- Thi gian: 30 pht

- Gdyhuieg dsuds

ncmcssd

-

Hn hp 1

- Sc kh N2

- Nhit : 60C

- Thi gian: 2,5 gi

- Vn tc khuy: 300 v/p

Hn hp 2

Etanol,

N,N -dimethylfocmamit - Ra, lc

- Sy kh 60C

Sn phm ghp

Vt li bin tnh

NH2OH.HCl 10% - Nhit : 60C

- Thi gian: 240 pht

- Vn tc khuy: 300 v/p

- Lc v sy kh 60C

Acrylonitrile 99,9%

Hnh 29. Quy trnh bin tnh to vt liu amidoxime ha t bt thn ay

56

3.3. c tnh ca vt liu bin tnh

a. b.

c. d.

Hnh 30. c im hnh thi b mt ca bt thn ay ban u (a), ay x l bng

NaOH 15% (b), ay ghp AN (c) v vt liu bin tnh (d)

c im hnh thi b mt ca bt t a ba u, sau khi x l vi NaOH

15%, ghp AN v vt li bin tnh c th hin trn hnh 30.

M a sa x l b NaOH c c loi b cc cht h c l m c o

b mt tr nn nh v c cc r . Sa k i amoxime ha, b mt bt t a tr

nn dy v xp so vi bt thn a ba u v x l bng dung dch NaOH.

57

Ph FTIR ca t a ba u, sau khi x l bng dung dch NaOH 15%,

ghp AN v vt liu bin tnh c th hin trn hnh 31, 32.

Hnh 31. Ph hp th hng ngoi ca bt thn ay ban u (a), sau x l NaOH

15% (b) v ghp AN (c)

Cc lin kt v nhm chc trong bt t a ba u, x l bng dung dch

NaOH, ng trng hp ghp AN v vt li bin tnh c xc nh bng ph

hp th hng ngoi. So snh ph bt t a sa k i x l NaOH (Hnh 31b), ph

bt t a sa k i p AN x t hi nh hp th v tr 2.260 cm-1

, biu th

cho s ko c ca lin kt N. Sa k i amidoxime a, ba nh hp th xut

hin v tr 2.260, 1.660 v 910 cm-1

t ng vi cc lin kt N, =N v N

OH do phn ng ca hydroxylamin vi nhm nitrile c th hi di p

trnh sau [38]:

58

(24)

ng thi, s suy gim c hp th ti v tr s sng 2.260 cm-1

trong

ph ca vt liu (Hnh 32) so vi ph bt t a sa k i p AN (H 31c)

chng t mt phn nhm nitrile t am ia v o p n ng amidoxime ha. Ph

hng ngoi ca vt liu xut hi nh hp th khong s sng 3.423 cm-1

v c

c ln th hin lin kt hydro trong nhm hydroxyl (OH) hoc lin kt NH

trong nhm (NH2).

Hnh 32. Ph hp th hng ngoi ca vt liu

59

c im in tch b mt ca bt t a ba u, sau khi x l bng

dung dch NaOH 15% v vt li c th hin trn hnh 33 v hnh 34. Kt qu

cho thy, qu trnh x l bng kim lm cho b mt t a m i so vi

t a ba . iu ny l cn thit nng cao hiu qu phn ng trng

hp ghp AN [44]. S lng nhm (OH) c kh tip c t l sa p n

ng v lm cho b mt m i . K i pH c t t m (OH) trn b mt

vt liu gii phng ra ion H+ trung ha kim, d n b mt vt li m in

k i pH t l [41].

Hnh 33. Th zeta ca bt thn ay ban u, sau x l NaOH 15% v vt liu

Vt li bin tnh c b mt m i so vi bt thn a x l NaOH

v bt thn a ba u. Chng t rng, vt li bin tnh c ghp vo cc

nhm (OH) l m t m in. Th zeta ca vt liu gim a k i pH t a i

t 2 n 6; khi pH > 6, th zeta gim chm v g k im k i t pH t

10 11. T t t zeta, s l in tch m b mt (cmole(-)

/kg) cng

ln khi gi tr pH cng cao (Hnh 34).

60

Hnh 34. in tch m b mt ca vt liu bin tnh cc pH khc nhau

3.4. Kh nng x l kim loi nng (Cu2+

, Zn2+

, Ni2+) ca vt liu bin tnh

3.4.1. Xc nh gi tr pH x l

N trnh by ph c tnh ca vt li bin tnh, vt liu c b mt

m in, gi tr pH c cao t pH c m in. Ti pH 6, m in ca b

mt kh l v k i t pH t m in b mt gim khng nhi . T i ,

loi b ng ca qu trnh kt ta cc ion kim loi, pH 6 l gi tr pH ph hp

i k p ph KLN ca vt liu. Do , i tr pH 6 c ch

thc hin cc th nghim i k x l ion kim loi

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