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Control of WastesProf. Attilio CitterioDipartimento CMIC “Giulio Natta”http://iscamap.chem.polimi.it/citterio/dottorato//
“The pessimist sees the difficulty in every opportunity. The optimist, the opportunity in every difficulty”
PhDIN INDUSTRIAL CHEMISTRY AND
CHEMICAL ENGINEERING (CII)
Attilio Citterio
Disposal of Effluent
Becoming increasingly costly Need to identify effluent cast for each product
- including aqueous waste
Development work should aim to minimise effluent BEFORE process reaches plant
Need to look at ALL aspects The most efficient processes generate the least
effluent- Catalytic Processes
Attilio Citterio
Disposal Routes
Biological Degradation- Aqueous waste- Aqueous organics- Not suitable for water-immiscibles
Incineration- Suitable for most organic liquid waste- Chlorine and Sulphur compounds may be expensive(They require scrubbing)
Landfill- Acceptable for innocuous solid waste- Widely-used for other wastes- More restrictions likely in the future
Attilio Citterio
Bio-treatment of Organic Molecules
Water solubility is not enough.• Factors which make a molecule more difficult to treat
biologically:- increasing molecular wt (particularly > 500)- water immiscibility- type of bonds: ester > amide > ether/ketone > S-O > P-O- stereochemistry- for aromatics: number and type of substituents
Cl, NO2, SO3H slow degradationOH, C=O, NH2 neutral or increase degrad.
- branching of alkyl chains, particularly quaternary centres, are a problem
- steric hindranceProducts must be non-toxic to organism, e.g. Quaternary ammonium salts, some heterocyclics, some organometallics are biocides
Attilio Citterio
C. Ibbetson, T.C.E., 1996, June, 23
0 100 1000 10000
99% 99.9%Cryogenic
Condensation50% 80% 95%
90% 95% 98%
50% 95% 98%
90% 95-98%
95% 99%
Adsorption
CarbonAdsorption
CatalyticIncineration
ThermalIncineration
Inlet VOC conc. (ppmV)
VOC Reduction Efficiencies - Different Technologies
Attilio Citterio
Solvent TALuft
mg/m3
UK (IPC)guideline
mg/m3
Equilibriumtemperature
TA Luft
TocomplyUK (IPC)
Acetone 150 80 86 -97Methanol 150 80 74 -94Dichloromethane 150 20 99 -118Toluene 100 80 64 -64MIBK 150 20 50 -50THF 100 80 86 -86
VOC Reduction
Attilio Citterio
Disposal Routes
Recycling- Precious metals- Nickel and other metals- Solvents
Neutralisation - Aqueous acids and bases
Disposal routes vary depending on the location of the site
Attilio Citterio
1991 1992 1993 1994 1995 1996
Fuel and power industryCombustion > 50 MW(t)
GasificationCarbonisation
Combustion (rem.)Petroleum
Waste Disposal IndustryIncineration
Chemical recoveryWaste-derived fuel
Mineral IndustryCement
AsbestodFibre
GlassCeramic
The Chemical Engineer, 28 March 1991
Integrated Pollution Control - Timetable
Attilio Citterio
Effluent Control in Process R&D
• Effluent control through process improvement- Synthetic route- Choice of reagent- Stoichiometry- Solvent- Work-up- Total process design
• Pollution Prevention Pays (3P)- 3M saved $420 million through a 3P scheme- 1000,000 tonnes of air pollutants eliminated
Attilio Citterio
3M’s 3P Program
• Product reformulation- Development of non-polluting or less-polluting products- Using different raw materials or feedstocks
• Process modification- Changing processes to control by-product formation- Incorporation of non-polluting or less-polluting raw materials or
feedstocks
• Equipment redesign- To perform better under specific operating conditions- To make use of available resources (such as by-products from
another process)
• Resource recovery- Recycling by-products (for sale or use in other processes)
Attilio Citterio
3M’s 3P Program
None of these concepts is new What is new is the Company commitment Paybacks were attained in less than three years Paybacks were due to
- Decreased raw material costs- Decreased waste management costs- Decreased energy costs- Improved product quality- Enhanced productivity- Decreased downtime- Decreased worker health risk- Decreased environmental hazards- Decreased long-term liability for clean-up, of waste- Improved public image for Company
Attilio Citterio
Corporate Measures
Prof Huisingh has developed a plan of corporate steps necessary for waste reduction- Develop a corporate environmental policy- Develop and use waste-reduction audit procedures- Involve employees in incentive awards programmes- Set corporate goals and timetables for waste reduction- Allocate responsibility, time and finance for waste reduction- Monitor progress on waste reduction programmes- Regularly inform all employees of progress- Update goals and timetables
Attilio Citterio
HN N
SHN NHMe
N
NCN
S
S
H3C
H3C
NCN
S
S
NH2CNBase
CH3NO2Base
NNO2
S
S
Me2SO4 Me2SO4
NNO2
S
S
H3C
H3C
O
SHN NHMe
N
CH2NMe2
NO2CN
CS2
Cimetidine Ranetidine
Synthesis of H2 Antagonist
Attilio Citterio
NCN
S
S
H3C
H3C
MeNH2
+
S N
SHN SMe
N
N
CN
NH2
NH2
S N
SNH2
N NH2
NH2
S N
SHN NHMe
N
N
CN
NH2
NH2
- MeSH
Tiotidine
Synthesis of Tiotidine
Attilio Citterio
NCN
O
O
H3C
H3C
MeNH2
+
S N
SHN OMe
N
N
CN
NH2
NH2
S N
SNH2
N NH2
NH2
S N
SHN NHMe
N
N
CN
NH2
NH2
- MeOH
Alternative Synthesis of Tiotidine
Attilio Citterio
Tiotidine - Problems with N-Cyanodithioimidocarbonate Route
• MeSH has a very low our thresold (1 ppb)
• TLV is 0.5 ppm
• 1 kg Tiotidine generates 0.5 kg of MeSH
• Emissions encountered during scale-up work (20 L)
• Therefore need to examine alternatives
Attilio Citterio
Tiotidine - Use of N-Cyanoimidocarbonates
• Replacement of the first alkoxy group is fast• Replacement of the second alkoxy group is
usually slow• Product is not very stable - rearranges
NCN
O
O
R
R
RO N
OCN
R
Attilio Citterio
N-Chloro intermediates explosiveGeneration of alkyl hypochlorite
NCN
O
O
R
RKCN + Cl2
ROH
NHO
O
R
RClCN + NaOR
CyanamideHCl
NO
O
R
R CN
Process requires simultaneousaddition of reagentsProcess difficult to scalePremixing of reagents investigated
Synthesis of N-Cyanoimidocarbonates
Attilio Citterio
Temperature Half-life
0 > 100 hours12 43 hours25 8.3 hours37 2.2 hours
Therefore, premixing not a problem
Simple process gives 55% yield on plant
Cyanamide - Half live in 36% HCl
Attilio Citterio
Is This Process Useful for Other Anti-Ulcer Drugs?
Cimetidine?Ranetidine?
ICI has in-house source of ClCN
Carbon disulphide is cheap
Require other sources of CX2Y2 or Cl2=NCN
Attilio Citterio
AcidWater
WaterSolventReactants
Filter
Filter
Final product(cake)
Wasteliquors
Reslurry
Product(cake)
Quench
Wasteliquors
Reaction
Case Study - Polaroid Dye Synthesis
Attilio Citterio
Case Study - Polaroid Dye Synthesis
• Two high-volume aqueous steam produced
• First steam heavily contaminated- Organic solvents, reaction by-products, heavy metal salts- Requires licensed external disposal
• Second stream less contaminated- But still requires external disposal
• Solution: Use second stream as quench for next batches- No equipment change- Costs only R&D and product testing- Waste volume reduced (60,000 gal in 1987/ 80,000 gal in 1988)
• Annual saving on transport and disposal of waste -$ 160.000 in 1988
Attilio Citterio
Rhone-Poulenc
Mitsubishi
H2O, heati)
Cl2
ii) H2O
OH O
OH
OH
OH
Cheap raw materialsSample processEffluent - 50 Kg/kg Product
H2 / Pt
O2CuCl LiCl
OH O
OH
OH
O
More expensive rawmaterialsComplex processEffluent - 2 Kg/kg Product
C. Mercier (R-P), Pure App. Chem., 1994, 1516
Vitamin E Intermediate
Attilio Citterio
- 35°C+ Li/NH3
HC CHO
R COH
HCCH
CH2
+ Li salt
- Lithium dissolved in ammonia at -35°C- Acetylene added to give dilithium acetylide- More acetylene added to give monolithium acetylide- Ketone added in solvent - reaction to give lithium enolate- Ammonia removed- Product released with diluted sulphuric acid- Layers separated- Solution of etinal stripped to remove polymeric material- Solution used in next step
H. Wiederkahr, Chem. Eng. Science, 1988, 1783
Etinol - Vitamin Intermediate
Attilio Citterio
Problems and Solutions Tried
Problems• Consumption of lithium - 50% of cost of intermediate
- 6.5 million dollars worth of lithium goes to the effluent plant in one year
• Acetylene and ethylene emission• Ammonia losses
Solution tried• Recycling lithium - unsuccessful• Replacement of lithium by cheaper alkali metals - much lower
yield • Catalytic process - low yield
Attilio Citterio
Laboratory Improvement
• Prepare lithium acetylide as before in ammonia
• Evaporate ammonia and replace with solvent
• Carry out reaction in solvent as before
• Gives 95% yield
• Can reduce lithium excess from 20% to 5%
Attilio Citterio
Etinol - Scale-Up Problems
• Unable to reproduce yield• Ammonia evaporation takes longer; temperature plateaux in reactor
before all ammonia removed• Found that complex formed between lithium acetylide and ammonia• 1:1 ratio of acetylide and ammonia absolutely critical
- below 1:1 - disproportionation to dilithium acetylide; reaction with ketone gives resins
- above 1:1 - polymerisation- at 1:1 - high yields achieved
• Need good process control• Result
- Process scaled up well- Other modifications to reduce effluent examined
Attilio Citterio
Etinol - Effluent Control
• Modified work-up to enable reprocessing of lithium by manufacture- Hydrolyse product with water, not acid- Separate phases- Neutralise organic phase with acid, then strip as before- Concentrate aqueous phase - recycle LiOH solution
• In separate studies, recycling of acetylene (by dissolving in ammonia) and ammonia implemented
• Total cost of implementing all 3 modifications - $ 4.6 million
Attilio Citterio
YIELD before after differencebased on ketone 82.0% 95.0% 13.0%based on lithium 68.0% 90.0% 22.0%RAW MATERIALSKetone 100 85.4 14.6Lithium 100 14.2 85.8Acetylene 100 48.2 51.6Ammonia 100 24.1 75.9Sulphuric acid 100 0.0 100.0Solvent 100 96.5 3.5Total 100 45.2 54.8
Etinol - Yield & RM Consumption
Attilio Citterio
WASTEPRODUCT before after differencePolymers 100 17.6 82.4Lithium salt 100 1.7 98.3Acetylene 100 (28.0) 100.0Ammonia 100 24.1 75.9Solvents 100 (96.5) 100.0Miscellaneous 100 8.3 91.7Total 100 5.3 94.7
Etinol - Waste Products
Attilio Citterio
N
+
NH2
OMe
NaNO2
MeOH - H2O, CO2
N N N
OMe
5 - 65 barCO2 + H2O H2CO3
(pKa = 3.3 ~ pKa )H2CO3 HNO2
Current azo dye production generates as by-products large amounts of salts.
Heterocyclic amines, normally difficult to diazotise, work well in CO2
Bayer - Salt-free Diazotisation