Indian Journal o f Fibre & Textile Research Vol. 29, June 2004, pp. 223-232

Efficacy of selective surfactants/detergents as washing agents on soiled white and dyed cotton fabrics

A K Samanta" & Sunanda Mitra

Textile Chemi stry Section, Institute of Jute Techno logy, 35 Ballygunge C ircul ar Road, Ko lkata 700 019, Indi a

and

Deepali Singhee & Smita Parekh

Department of Textiles & Clothing, J . D. Birla Institute, II Lower Rowdo n Street, Ko lkata 700 020, India

Received 18 March 2002; revised received alld accepted 25 Februwy 2003

Four different types of surfactant, name ly alkyl benzene sulphonate (A), sodium lauryl sulphate (B), glycerol monostearate (C) and di steary l dimethyl ammonium chloride (D), have been used in single and multiple washing of a soiled white/dyed cotton fabric to determine the ir critical micelle concentratio n (CMC) values and to assess the ir washi ng perfo rmance in terms of changes in some o f the physica l properties of fabrics, per cent soil removal from soiled white fabri c and max imum retention of colo ur depth of dyed fab ric . The washing performance of each surfac tant at lower concentrati on level by multi ple wash cycles has also been studied. Wash fas tness rating by grey scale and washing performance in terms of retention of colour depth of reac ti ve dye dyed cotton fabric have been assessed and compared by measuring the corresponding K/S values and colour d iffe rence values after washing with these surfac tants by ISO-II and ISO-III methods. It is observed that the CMC value and the corresponding degree o f soil removal at CMC level are 1.9 % and 90.8 % fo r surfactant A, 1.5 % and 90.6 % for surfactant B, 2 % and 92 % fo r surfac tant C, and I % and 39.4 % fo r surfac tant D respecti ve ly . On multiple wash, the surfac tants C and D do not show good performance at lower concentration (0.5- 1 %), wh ile the surfac tant B is found to be better than others. Considering the changes in phys ical properties of fabrics after washing, washing performance, critica l micelle concentratio n of surfac tants and rete nt ion of colour depth after washing, the surfactant B shows an overall balanced performance.

Keywords: Co lour strength, Cotton, Crit ical micelle concentration, Detergent , Surfac tant , Wash fastness IPC Code: Int. CI. 7 D06L ]/02

1 Introduction Detergent is a type of surfac tant which is capable of

cleaning dirt/dust/adhered particles (oi l/water/air borne) from fabric surface by suitable washing procedure. Household commercial detergents are of complex fo rmulations containing di fferent types of substances among which surfactant is the major constituent and contributor; the other substances bei ng builders, alkali/pH controller, chelating or complexing agents, ion exchangers, fabric softeners, corrosion inhibitors, foam controlling agents, bleaching agents/activators, fluorescent brighteners/ whitening agents, enzymes, fragrances/ perfumes, fillers and other additi ves as specific property builder/washing efficiency improver l

,2. Moreover, surfac tants have many advantages3 over ' o rdinary soaps used in home washing in terms of stability towards hard water and higher wetting power.

"To who m all the correspondence sho uld be addressed. Phone: 24765299; Fax: +9 1-33-24750996; E-mai l;ijt@caI2.vsnl.net. in

Depending on what type of charge is present in the long chain portion of the surfactant molecule in wash liquor (usually water) after dissociation, the surfactants are div ided into the following fo ur groups:

(i) Anionic surfactant - Alkyl benzene sulphonate and Sodium lauryl sulphate.

(ii ) Non-i onic surfactant - Lanolin ethoxylate and Glycerol monostearate.

(iii ) Cationic surfactant Dodecyl dimethyl ammonium chloride and Distearyl dimethyl ammonium chloride.

(iv) Amphoterics - Lauryl dimethyl betaine and Coco-ami do propyl betaine.

A specific class of detergent or a specific surfactant has its specific effec' ;veness but the main function of detergent is the capability to remove soil/adhered particles from textile surface and the prevention of redeposition during washing. The additives added in commercial detergents are only property improvers ,

224 INDIAN J. FIBRE TEXT. RES., JUNE 2004

but basic or main function depends on the action of main surfactant present in the detergent formulations.

Cotton4.5 fibre attracts dirt/dust/soil by both dry and

wet soiling mechanism as it has good absorptivity and easy proneness to moisture absorption . Thus, the cotton, either dyed or undyed, tends to attract dirt/dust/soil and therefore it is necessary to find out suitable type of surfactant for effective washing of cotton fabric without harming its major textile related properties. There is limited availability of scientific literature on this issue, particularly for cotton fabric, except a few discussed below.

Compartive study of cleaning efficiency of different types of synthetic detergent on polyester/cotton fabric was reported by Singh and Bhanote6

. Effect of laundering on mechanical properties of some apparel fabrics was studied by Munshi el al.7

. Study of some physical and chemical effects of domestic laundering process using selective surfactant was reported by Bishop8. Effect of laundering on cloth weight and abrasion resistance of polyester/cotton blended fabrics was also studied by Bhavani and Shailaja9

.

Effectiveness of two cleaning agents on white polyester/cotton blended cloth was compared and reported by Jayashree and Shailaja lo. Effect of protease enzyme assisted washing of cotton fabric for proteinic soi ls was studied recently by Kearny el al.ll. Also, the effectiveness of washability of cotton using combination of different surfactants (non-ionic and cationic) was studied by Shimonura el al l 2

.

Most of the above studies are either piece-meal approach or mostly done for polyester-cotton blended fabric only and not for cotton fabric. Therefore, the present study was undertaken with the following aims and objectives: (i) to study the effectiveness of selective pure organic surfactants in single and multiple washing of a soiled white cotton fabric, (ii) to determine the critical micelle concentration and corresponding per cent soil removal by selective surfactants for their effective application in minimum or appropriate concentration level as detergent for washing of a soiled white cotton fabric, (iii) to study the changes in surface colour strength and wash fastness rating of reactive dyed cotton fabrics by washing with selective surfactants, and (iv) to study the changes in common textile-related physical properties by the action of selective surfactants for single or multiple wash cycle.

Thus, attempts have been made to find out the most suitable surfactant for washing of a white and dyed cotton fabric efficiently .

2 Materials and Methods

2.1 Materials

2.1.1 Fabric

100% bleached (white) plain woven cotton fabric , having the specifications: warp thread density, 116 ends/dm; weft thread density , 82 picks/dm; area density, 95.0 g/m2

; warp yarn count, 32.2 tex; weft yarn count, 29.0 tex; and fabric thickness, 0.30mm, was used.

2.1.2 Chemicals and Dyes

Commercial grade of graphite powder, soda ash, conc. HCI , coconut oil and paraffin oil were used. A hot brand reactive dye, Procion Brilliant Orange H2R (C.1. Reactive OrangeI3), obtained from ATIC Industries, Valsad, Gujarat, was used.

2.1.3 SlIrJactants

The surfactants of known .chemical structure as shown in Scheme 1 were used as detergents for the study.

2.2 Methods

2.2.1 Method oj Soiling

Soiling mixture was prepared using the ingredients such as graphite powder (0.15g), coconut oil (Sg) , paraffin oil (5g) and water (1000ml) according to the U.S. Pat 31 73 877 (16 May 1965) and IS: 5785, Pt V (1976).

The soiling of the fabric sample was done by keeping the sample immersed in the above soiling mixture for 30min at room temperature using a launder-O-meter with stirring. The soiled samples were then removed, squeezed and dried in air.

2.2.2 Single Washing/Multiple Waslzing Single or multiple (2-5) cycles of washing of the soiled white cotton fabric samples and single washing of the unsoiled dyed samples were carried out in a launder-O-meter following ISO-II washing method using different concentrations (0.5 %, 1 %, 1.5%, 2%, and 5%) of aqueous solution of surfactants.

2.2.3 Determination oj Moisture Regain The moisture regain of selective cotton fabric

sample was determined as per the IS: 1964 (1970) oven dry method 13. The fabric samples were dried up to a constant weight in a laboratory drying oven at 110°C, weighed and conditioned for 72 h at 27± 2°C and 65± 2% RH by keeping in a desiccator filled with saturated solution of sodium nitrite. After 72 h of moisture absorption by the fabric sample in standard

SAMANTA et al.: EFACACY OF SURFACTANTSIDETERGENTS AS WASHING AGENT ON COTTON FABRIC 225

Surfactant Manufacturer Chemical Structure

H I

Alkyl benzene sulphonate(A)

Gandhi Parekh Corpn Pvt Ltd, Mumbai

S03N.

{where n+m = 7-10}

Sodium lauryl sulphate(B) Diamond Chemical Corpn Mumbai

-Glycerol mono stearate(C) Ashvind Chemical. Mumbai

CH3 (CH2) 16 COO - CH2 I

CH10H I

CH10H

+

Disteryl dimethyl LafTans Petrochemical Ltd [ CH3 OOCC 17H33 ] Mumbai ~ -- C\· ammonium chloride(D) ~

CH3....-- ____ OOCC 17H33

Scheme l-Chemical structures of surfactants used

condition, the samples were weighed carefully and the moisture regain value for each sample was calculated.

2.2.4 Determination of Weight Loss on Washing

The weight loss percentage of cotton fabric after single/multiple washing was also determined by measuring oven dry weight of the sample before and after washing as per the IS: 1964 (1970) method 13

.

The oven dry weight of the soiled fabric sample before washing was obtained by lab drying of the sample at 110°C followed by weighing till constant weight. Soiled fabric samples were then washed by ISO-II washing method using 1 % solution of surfactants. After washing, the samples were further dried in lab drying oven till constant weight and the dry weight of after-washed fabric samples was taken and used to calculate the weight loss percentage as per the following formula:

[

(Dry weight of unwashed samPle]

W . h I 01. - Dry weight of washed sample) 100 elg toss -10= x

Dry weight of unwashed sample

2.2.5 Determination of Shrinkage on Washing Washing shrinkage test was carried out as per the

IS: 9 (1963) method13 for single wash of 30cm x

30cm fabric sample in each case. Warp -wise and weft -wise datum lines (Wcm x Wcm) were drawn by permanent marker on the selected fabric samples before washing for the measurement of warp-way and weft-way shrinkage. Length of datum lines was remeasured again after washing and the shrinkage was calculated using the following relationship:

% Shrinking=[ 4~~ ]XWO

where Lo is the original length of datum line before washing; and Lh the final length of datum line after washing.

2.2.6 Determination of Degree of Soiling and Soil Removal

After soiling white cotton fabric, the degree of soiling 14

,15 in the soiled fabrics was determined before subjecting it to washing by using the following formula:

Degree of soiling (% soiling)= [Ro - Rs 1 x 100 Rs •

where Ro is the reflectance value of unsoiled white fabric; and R" the reflectance value of soiled white fabric.

226 INDIAN J. FIBRE TEXT. RES., JUNE 2004

For the measurement of per cent soil removal of washed fabrics, the following formula was used:

Per cent soil removal (PSR)= L s x 100 [

R -R 1 Ro-R,.

where RL is the reflectance value of soiled fabric after washing. The reflectance values of the fabric samples were measured using a portable B YK -Gardner reflectance spectrophotometer, associated computer and relevant software.

2.2.7 Determination of Breaking Strength and Elongation -at Break

Determination of warp -way breaking strength and elongation -at -break was carried out by ravelled strip method 13 as per the IS : 1969 (1968).

However, the specific size of the sample (gauge length and width) used was 50mm x 20mm (after ravelling) which was taken from a randomly cut warp -way long sample of 100mm x 25mm size. The breaking strength and elongation -at -break were measured using a universal tensile strength tester (Model Instron 4411) and the average of 10 readings was taken for each sample.

2.2.8 Dyeing with Reactive Dye The dyeing of cotton fabric sample was carried out

using a selective reactive dye (1 % owf) with the material -to -liquor ratio of 1: 30, 20gpl soda ash and 75gpl common salt as auxiliaries which were added in the dye bath as per the usual sequence and timings of the standard reactive dyeing procedure l 6

. The dyebath was initially set at 50°C with dye and the textile substrate was put in the dyebath. After 10 min of keeping the material in dyebath at 50°C, half of the required salt was added . After 20 min of dyeing at 60°C, rest 50% of the salt was added in the dyebath. Then, the dyebath temperature was raised to 85°C in 30min. After 50min of dyeing, half of the alkali (Na2C03) was added in the dyebath at 85°C. After another 15min, rest half of the alkali was added and dyeing was continued for 60min. After the dyeing was over, the dyed fabric was washed with hot water, soaped, washed with cold water, rinsed and dried in air.

2.2.9 Determination of Wash Fastness Wash fastness rating of cotton fabric samples dyed

with reactive dyes was assessed as per the IS: 3361 (1979) and IS: 764 (1979) methods 13, after washing the samples following the equivalent to ISO-II and

ISO-III washing conditions (for ISO-II: surfactant, 5gpl; temperature, 50± 2°C; material -to -liquor ratio, 50; and time, 45 min. For ISO-III: surfactant, 5gpl ; soda ash, 2gpl; temperature, 60± 2°C; material -to -liquor ratio 50; and time, 30 min).

The fabric samples to be tested were cut to a size of 10 cm x 4 cm and sandwiched between two pieces of cloth (bleached cotton fabric on one side and bleached wool fabric on other side). After sandwiching the samples, the four sides were stitched well. These samples were subjected to washing in a SASMIRA launder-O-meter using all the four surfactant solutions of appropriate concentration as per the ISO-II and ISO-III methods. The change in colour of the washed fabric and staining on adjacent cotton/wool fabric were assessed/rated using the corresponding grey scales, verified by Macbeth 2020 plus reflectance spectrophotometer and associated software.

2.2.10 Measurement of Surface Colour Strength Surface colour strength 17,18 (K/S val ue, indicating

dye shade depth on surface) was determined by measuring corresponding reflectance value using Macbeth 2020 plus reflectance spectrophotometer and by calculating the K/S value using the followin g Kubelka -Munk equation:

(1 R / K / S = - Amax = DC C

2RA max

where c is the concentration of dye; DC , a constant; and

R" max, the reflectance of fabric sample at a particular wave length where maximum absorption occurs.

Colour difference (11£) was measured by L*, a*, b* values using Colourlab plus software and Macbeth 2020 plus reflectance spectrophotometer using the following CIE-Lab equation:

where L*= 116 (yly,,)I/J -16

a* = 500[(xlx,,) 113 - (y - y,J 1/J]

b *= 200 [(yly,,) 113 - (z - Z,,)1I3 ]

where x", y" and z" are the three tristimulus values of a standard white surface of MgO (or eq uivalent surface of standard white tile) and x, y and z are three tristimulus values of the corresponding sample.

SAMANTA et at.: EFFICACY OF SURFACTANTSIDETERGENTS AS WASHING AGENT ON COTION FABRIC 227

3 Results and Discussion

3.1 Effect of Single Wash on Soil Removal and Physical Properties of Fabric

Table! shows that the pH of the alkyl benzene sulphonate (A) solution is found to be acidic while that of the sodium lauryl sulphate (B) and glycerol monostearate (C) solutions is found to be neutral. The pH of the solution of distearyl dimethyl ammonium chloride (D) is found to be slightly alkaline. The washing of fabric sample was carried out in a launder­O-meter as per the ISO-II condition at 50± 2°C for 45 min using 1 :50 material -to -liquor ratio and 1 % surfactant solution. The weight loss for single wash (ISO-II method) with 1 % surfactant A solution is found to be much higher (up to 3.56%). This may be due to the acidic action of surfactant A, while the weight loss for other surfactants B, C and D at the same concentration varies from 0.3% -0.8%.

In spite of weight loss on washing for different surfactants being much different, the warp -way and weft -way shrinkage values of fabric on washing are found to be much nearer for all the selected surfactants; the warp -way shrinkage varies between 5% and 6% and the weft -way shrinkage varies between 1 % and 1.5%. Relatively higher warp-way weaving strain on the fabric might have caused higher warp-way shrinkages in all the cases.

Data related to warp-way breaking strength and breaking extension (elongation-at-break) of cotton fabric after washing with different surfactants indicate that for surfactants Band D, the breaking strength values are found to remain unaltered or much closer to that of the control sample (Table 1). However,

some reduction in breaking strength is observed for surfactant C. The acidic surfactant, i.e. alkyl benzene sulphonate (A), shows an appreciable reduction in breaking strength but maximum increase in breaking extension. However for all other surfactants, the breaking extension values increase to a lesser extent than that observed for surfactant A in case of single wash. This increase in breaking extension after washing may be considered partly as a consequence of 5 - 6 % warp -way fabric shrinkage. The higher loss in breaking strength for surfactant A may be understood as a consequent effect of higher weight loss (up to 3.56%), while observed highest increase in breaking extension may be due to the higher disorientation, leading to higher shrinkage. However, it cannot be evidenced directly from the warp -way shrinkage results only. Hence, this highest increase in breaking extension should also be due to the possible change in internal orientation of polymer/fibre chains of cotton owing to the effect of acidic degradation by surfactant A.

Table 1 indicates that there is no noticeable alteration in moisture regain pattern after washing with surfactant, except some minor sample-to-sample variation in the corresponding observed data.

After standard soiling of the bleached (white) cotton fabric, it was washed with 1 % aqueous solution of surfactants at the pre-set ISO-II condition of washing, and the per cent soil removal was determined (Table 1). The increasing order of per cent soil removal (PSR) from soiled white cotton fabric on single washing by ISO-II method with 1 % solution of selective four surfactants is:

Table 1- Effect of single washing (ISO -II) with I % solution of surfactants on physical properties and per cent soil removal from soiledlbleached (white) cotton fabric

Surfactant eH of wash bath Weight Fabric shrinkage, % Warp-way Warp-way Moisture Per cent Initial Final loss Warp Weft breaking breaking regain soil

% strength extension % removal N/mm %

Nil (Control untreated) 10.49 15.16 8.76

Anionic Alkyl benzene sulphonate 4.0 4.0 3.56 5.0 1.0 7.93 21.44 8.71 67.56

Sodium lauryl sulphate 7.0 7.0 0.68 5.0 1.2 10.44 19.06 8.10 80.63

Non-ionic Glycerol monostearate 7.0 7.0 0.34 6.0 1.5 9. 11 19.04 8.82 57.65

Cationic Dodecyl dimethyl 8.0 7.5 0.77 5.5 1.0 10.38 17.99 8.43 39.41 ammonium chloride

228 INDIAN 1. FIB RE TEXT. RES., JUNE 2004

Surfactant D < Surfactant C < Surfactant A < Surfactant B

(PSR=39.4) (PSR=57.6) (PSR=67.6) (PSR=80.6)

Hence, from the above results, surfactant B is rated as best wash performer among all the surfactants studied as far as per cent soil removal and overall balance of physical property parameters of cotton fabric are concerned.

3.2 Effect of Single Wash with Varied Surfactant:> Concentrations on Per cent Soil Removal

Relationship between varying concentration of each surfactant and its per cent soi l removal efficacy is studied and the results are shown graphically in Fig. I. It is revealed from the curves A, B, C and D (for corresponding surfactants A, B, C and D respectively) that with the increase in concentration of surfactant the cleansing efficiency (per cent soi l removal) increases up to a certain limit after which it remains constant or levels off. Th is was also observed earlier by Galbraith 19. This limit of surfactant is known as critical micelle concentration (CMC) which is defined as the limiting concentration of a surfactant after which an increase in concentration of that surfactant has no effect on cleaning efficiency or it is such a concentration level of a surfactant where per cent soil removal efficacy of that surfactant levels off. The CMC values of the selective four surfactants are different. The observed CMC values and the corresponding percentage soil removal are in the following order:

Surfac tant C > Surfac tant A > Surfactant B > Surfactant D

(CMC = 2%) (CMC = 1.9%) (CMC = 1.5%) (PSR = 92) (PSR = 90.8) (PSR = 90.6)

(CMC= 1%) (PSR = 39.4)

Here, sUlfactant D shows lowest CMC value ( I %) and per cent so il removal (39.4% only for 1 % surfactant). Even at 5% concentration, the per cent soil removal for surfactant D is found to be 35 .8, while surfactant B shows 90.6% soil removal at 1.5% concentration (CMC level) . Between the other two surfactants A and C, the CMC value of surfactant A is 1.9% with corresponding percent soi l removal efficacy of 90.8 while the CMC value of surfactant C is 2% with corresponding per cent soi l removal efficacy of 92.Thus, it is clearly observed that none of the surfactant shows complete removal of soil , possibly due to the tenacious holding of so il particles in fibre and yarn interstices and also due to the hardness !impurities present in the water used, which was earlier explained by Prato et al.2o and Reeves et ap l.

100 B

90 C A

80

"iii 70 > 0 E 60 Q) L-

'0 en 50 C Q) 40 II L- "'t>D Q)

a.. 30 ~ Alkyl benzene sulphonate (A)

20 0---0 Sodium lauryl sulphate (8) - Glycerol mono stearate (C)

10 0-----0 Oistearyl dimethyl ammonium chloride (0 )

I) 0 ' ,5 1" 1'9

0 2 3 4 5

Surfactant conc.,%

Fig. I-Effect of sing le washing using varied concentration of different surfactants on per cent soil removal efficacy of cotton fabri c

From these findings , it is very clear that surfactant B (sodium lauryl sulphate) gives a better balanced washing performance and shows high level of per cent soi l removal (90.6) and low level of CMC (1.5 %) in comparison to other surfactants studied. On the other hand, surfactant D has low CMC value coupled with low per cent soil removal efficacy and sUlfac tants A and C have higher CMC values with comparable or little higher per cent soil removal efftcacy than surfactant B. Moreover, surfactant B at 1 % concentration also gives the highest percentage of soi l removal (about 80.6%) than any other surfactants studied at comparable conditions of washing. So, to consider the overall balanced washing performance by a surfactant having moderately low CMC value with reasonably high soil removal efficacy, among the four surfactants studied, the surfactant B is found to be the best wash petformer.

3.3 Effect of Multiple Wash on Per cent Soil Removal Another useful study was made by using much

lower concentration (0.5%) of surfactants to assess whether the same level of per cent soil removal can be achieved as obtained by using 1 % or CMC level of surfactant concentration by repeated multiple wash (2 -5 wash cycles) instead of si ngle wash.

Figure 2 shows the per cent soil removal from a soiled white cotton fabric against number of multipl e wash cycle using 0.5 % conceillration of each

SAMANTA et al. : EFFICACY OF SURFACTANTSIDETERGENTS AS WASHING AGENT ON COTTON FABRIC 229

surfactant. Each surfactant shows a progressive increase in per cent soil removal as the number of wash cycles increases. It is further observed that among the four surfactants studied, the surfactant B shows the highest percentage of soi l removal efficacy for any number of wash cycle at O.S % concentration. At the fourth wash cycle, surfactant B surpasses (PSR becomes 86.3) the corresponding per cent soil removal level achievable for the same surfactant at 1 % concentration level for a single wash. Also, at the fifth wash cycle, O.S % surfactant B almost achieves cleaning efficiency (PSR 88.S, which is 90.2 at CMC level) very nearer to that obtainable at its I .S% CMC level for a single wash. For the surfactants A, C and D, the level of per cent soil removal on fifth wash cycle at O.S% concentration level remains in between 40 and SO, which is found to be much lower (except surfactant D) against the corresponding value of their per cent soil removal in single wash at CMC level of concentration for each surfactant. Hence, in this study of effect of multiple wash usi ng lower surfac tant concentration (O.S %) level , surfactant B gives best cleaning effici ency at 4th or Sth wash cycle during multiple wash.

3.4 Effect of Single Wash on Wash fastness of Reactive Dyed Cotton Fabric

The wash fastness rating of reactive dyed cotton fabric using S% (Sgpl) surfactants concentration was studied on washing the dyed samples by both ISO-II and ISO-Ill methods. Therefore, the corresponding changes in loss of depth of colour was assessed by both grey scale rating and instrumental measurement of colour strength , and colour differences determining KlS values and !J.E values usi ng reflectance spectrophotometer with computerised colour measurement software. The results are shown in Table 2. It is observed fro m the !J.E values of samples washed with the selective surfactants (Sgpl) at the comparable condition of washing by ISO-II and ISO­III washing methods that the lowest loss of depth (minimu m !J.E values) of colour is observed by surfactant B though it shows a marginally lower K/S value than expected after washing by ISO-III method, but thi s is not reflected in corresponding !J.E value. This may be due to some unknown effect or interaction of additional soda ash (alkali ) either with the surfactant/fabric or the dye for which the K/S val ue gets apparently lowered, although !J.E values do not show thi s trend. Surfactants D and A, as compared to surfactant B, on washi ng show higher colour change (highcr !J.E values) (Table 2). Surfactant B

90

80

70

ro 60 > 0 E Q)

50 L-

'0 tJ)

C 40 Q) u

03 CL

30

20

10

0 0

B

D A

o .....- Alkyl benzene sulphonate (A) 0----0 Sodium lauryl sulphate (8) ..- Glycerol mono stearate (C) 0----0 Distearyl dimethyl ammonium

chloride (D)

2 3 4 5 Number of wash cycles

Fig. 2-Effect of mult iple washing (2-5 cycles) using different types of surfactant ( I % solution) on per cent soil removal efficacy of soiled white cotton fabric

thus shows reasonably good wash fastness rating. Colour fading of dyed cotton fabrics including that for reactive dye on multiple washing has been recently studied extensively22 using a standard surfactant but the effect of di ffe rent types of surfactant on colou r fading is not reported. For all the surfactants, the loss of depth of colour is, to some extent, expectedly hi gher in ISO-III method of washing than that in ISO­II method of washing, though the diffe rences are not too much for the obvious reason of hi gher wash fas tness expected for reactive dyes due to their covalent nature of bonding with cellulosic fibres.

3.5 Effect of Single Wash on Loss of Depth of Colour This study was made to understand the effect of

vary ing concentration of surfactant on wash fastness rating, dev iating from the recommended soap/detergent concentration for ISO-II method, but keeping other conditions of the washing strictly as per ISO-II washing conditions. The relative surface depth of colour in terms of K/S values after single wash of reactive dyed cotton fabri c with O.S -S % solut ion of selective surfactants is graphically shown in Fig.3. It is observed from curves A, B, C and D that for surfactant A, the surface colour strength value is reduced (amounting to a small extent) at higher rates as compared to other surfactants with the increase in surfactant concentration from 0.5% to 1.9% (2% level), after which there is almost no further loss in

230 INDIAN J. FIBRE TEXT. RES., JUNE 2004

Table 2 - Wash fastness by grey scale and instrumental assessment for change in surface depth of colour of the reactive dyed cotton sample using 5gpl solution of selective surfactants

Surfactant

Nil (Control)

Anionic Alkyl benzene sulphonate

Sodium lauryl sulphate

Non-ionic Glycerol monostearate

Cationic

ISO-II Loss of depth of colour

Grey scale KlS value D.E

3-4

4

3-4

1.2 (100)

-I .02 (85.0)

1.06 (88.4)

1.01 (84.7)

1.42

1.09

1.20

Wash fastness rating

Staining on cotton

(Grey scale)

3

4

3-4

ISO-1I1 Loss of depth of colour

Grey scale KlS value D.E

3-4

4

3

1.2 (100)

1.03 (85.8)

0.98 (81. 7)

1.03 (85.8)

1.45

1.20

1.35

Staining on cotton

(Grey scale)

3

3-4

3

Dodecyl dimethyl 3-4 1.03 1.32 3 3 1.04 1.85 3 ammonium chloride (85 .9) (86.7)

Values in parentheses represent the relative change in colour strength in parts as compared to that of the standard control sample whose initial colour strength is considered to be 100 parts.

surface depth of colour. On the contrary, for use of 5% surfactant concentration for washing of reactive dyed cotton fabric, a slight upward trend in K/S values is observed for almost all the surfactants. It is also observed that the surfactant A has CMC value near to 1.9% (Fig. 1 ) and hence this observation in Fig.3 corroborates the earlier observation of Fig.I. For surfactants B, C and D, with the increase in surfactant concentration from 0.5% to 1.5%, the reduction in colour strength values on ISO-II single wash of the reactive dyed cotton fabric is always smaller than that of surfactant A. Among the surfactants B, C and D, the relative rate of surface colour strength reduction for ISO-II wash is in the following order:

Surfactant A > Surfactant D > Surfactant C > Surfactant B.

For surfactant B, the reduction in surface colour strength by ISO-II wash continues almost up to 1% surfactant concentration after which there is no further loss in depth of colour, though at 1 -5% concentration there is a very very small increasing trend of surface colour strength value.

For surfactant C, the small reduction in surface colour strength also continues up to 1 % surfactant concentration and then it shows an upward trend at 2% concentration after which there is almost no further loss in surface depth of colour. At 5%

~ Alkyl benzene sulphonate (A)

0---0 Sodium lauryl sulphate (8)

- Glycerol mono stearate (e)

0--0 Distearyl dimethyl ammonium chloride (D)

~~ ! i ~ Ii ' i .1

01'--'~~ __ T-i~~:L! ____ ~ ______ ~ ____ J ,L ! i! o!~ ,'3 I'~'

2 3 4 5

Surfactant conc.,%

Fig. 3-Effect of single washing (ISO-II method) using varied concentration of different surfactants on loss of depth of colour in terms of KIS values of reactive dyed cotton fabric

concentration, surfactant C shows a minor upward trend in the observed KIS value. For surfactant D, the surface colour strength follows the trend similar to that of surfactant C, but shows a little higher loss in surface depth of colour at all levels of surfactant concentration.

However, the interesting observation of the little upward trend of KIS values at higher (5%) level of

SAMANTA et af.: EFFICACY OF SURFACTANTS/DETERGENTS AS WASHING AGENT ON COTTON FABRIC 231

concentration for all the four surfactants, particularly either after different threshold limit of corresponding CMC level of concentration for different surfactants or at 5% level of concentration of surfactants, can be explained by the known phenomena of the effect of increased orientation of the dye molecules occurring predominantly on washing with higher surfactant concentration, thereby increasing the reflectance or lusture of the coloured surface and showing a minor/small increased K/S value (Fig.3).

4 Conclusions 4.1 The critical micelle concentration (CMC)

values of surfactants A, B, C and D for a single wash (ISO-II) of cotton fabric with varying surfactant concentration are found to be 1.9%, 1.5%, 2% and 1 % respectively and the corresponding per cent so il removal values at corresponding CMC level s of surfactant concentration are 90.8, 90.6, 92 and 39.4 respectively.

4.2 Surfactant A (alkyl benzene sulphonate) being acidic in nature shows noticeable weight loss and some loss in fabric tenacity and lesser per cent soil removal efficacy, while surfactant B (sodium lauryl sulphate) shows a marginal weight loss, almost no loss in tenacity and highest per cent soil removal efficacy after single wash (ISO-II condition) of a soiled white cotton fabric using I % surfactant solutions.

4.3 Among the fo ur surfac tants, for single wash with I % surfactant solution, surfactant B shows 80.6 per cent soil removal, while per cent soil removal obtained using 0.5% surfactant B for single wash is 38.5. However, by increasing the number of wash cycles, in multiple wash , even using (0.5%) surfactant concentration , the corresponding per cent soi l removal to be achi evable in single wash at CMC level can also be nearl y achieved fo r surfactant B by 5 wash cycles. At the 51h wash cycle, using 0.5% concentration level, surfactant B also shows highest (88.5%) per cent soil removal compared to 40-50% soil removal by other surfactants studied.

4.4 The wash fas tness rating of reactive dyed cotton fabric in terms of hi gher retention of surface depth of colour after washi ng (both by ISO-LI and ISO-III using 5 gpl surfactant solution) is found to be relatively better in case of surfactant B, followed by surfactants D and A.

4.5 Despite the loss in depth of colour from reactive dyed cotton fabric on washing, there is an upward trend of increased K/S value to a minor extent at 5gpl concentration of all surfac tants. This may be

considered to be an expected consequence of higher orientation of dye molecules on washing with higher level of surfactant concentration.

Form the above studies, it may be concluded that surfactant B (Sodium lauryl sulphate) is found to be the most suitable among the other surfactant studied considering washing performance, CMC values, overall balance/retention of physical properties after wash and minimum extent of loss of depth of colour after washing for dyed cotton textiles.

Acknowledgement One of the author (AKS) is thankful to AICTE,

Govt. of India, for AICTE's TAPTEC-CAPDS project grant (1999-00 to 2002-03) to the Textile Chemistry Section of Institute of Jute Technology , Kolkata, from which portable reflectance spectrophotometer was procured and used in this work. The authors SP, DS and SM are thankful to Prof. (Dr.) Prabir Ray, Principal , IJT, Kolkata, fo r providing all support and facilities to carry out a substantial part of the work at IJT. They are also thankful to Dr. Jharna Sengupta, Principal, J. D. Birla Institute, Kolkata, for her advice, contribution and necessary support during the study.

References 1 l akabi G & Lohr A, Detergents and Textile Washing:

Principles and Practice (YCH Publisher, New York), 1987. 1. 2 Karsa R David, Rev Prog Color, 20 (1990) 70. 3 Porter M R, Handbook oj Suifactants (HM Publi sher,

London), 1988, 6. 4 Cook Gordon, Handbook oj Textile Fibres, Pmt I (Merrow

Publishing Co. Ltd, London), 1993, 3S. S Corbman B P, Textile Fibres to Fabrics (Mc Graw-Hill Book

Co., Singapore), 1983,246. 6 Singh 0 P & Bhanote S, Text Trend, 42 ( 1999) 29 . 7 Munshi Y G, Ukidve A Y, Raje C R, Bhaskar P & Pai S D,

Resl/me' oj papers, 33rd Joilll Technological ConJerence of ATlRA, BTRA SITRA & NITRA (Bombay Textile Research Association, Bombay), 1992.

8 Bishop D P, Am Text lilt , 6 1 (199S) 263 . 9 I3 havan i K & Shai laja D N, Text Dyer Prillter, 30 ( 1997) 15.

10 Jayashree Y & Shailaja D N, Text Dyer Printer, 31 ( 1998) II. 11 Kearny D, Robert Q, Price J & Cui X, Text Res J . 70 (2000)

180. 12 Sh imonura K, Onozawa H & Komiyama I, J Japw/ Res Assoc

Text End Uses , 42 (200 1) 50. 13 Halldbook oj Textile Testing, SP- 15-1 981 (Bureau of Indi an

Standards, New Delhi , India), 1982,22 1,229,277, 278. 14 Mark H ,Wooding N S & Atlas S M, Chemical after

Treatments of Textiles (Wiley Inter Sc ience, New York). 1970. 469 .

IS Som N C, Colol/rage, 5S ( 1985) 55. 16 Samanta A K, Das D & Dasgupta P C, Illdiall J Fibre Texl

Res, 22 ( 1997) 53. 17 Samanta A K, Indiw/ Text J , 105 (1995) SO.

232 INDIAN J. FIBRE TEXT. RES., JUNE 2004

18 Samanta A K, Fundamental of instrumental colour measurement, colour tolerances and introduction to computerised colour matching, paper presented at the Short Course on Bleaching, Dyeing, Printing & Finishing of Jute, Institute of Jute Technology, Kolkata, June 1994.

19 Galbraith R L,} Home £con, 52 (1960) 352. 20 Prato H H & Morries M A, Text Res }, 54 (1984) 637. 21 Reeves W A, Beninate J V & Drake G L, Am Dyest Rep. 51

(1968) 1053. 22 Phillips D A S, Text Asia, 32 (200 I) 31.