| GREEN CHEMISTRY : GREEN CHEMISTRY Dr A.Sankaranarayanan
Analytical Chemistry Division
B A R C |
| Steps in Chemical process implementation : Chemistry is mainly used for materials production.Analytical chemistry makes it possible to characterize them.
Chemical process-Identification
Thermodynamic feasibility –
Kinetics
Economic considerations—
GOAHEAD decision Steps in Chemical process implementation |
| Green chemistry : Green chemistry Risk management-chemicals and materials
Pollution philosophy..
Reinvention of existing chemical processes
Integrating multi disciplinary approach
Reducing intrinsic hazards
Enhancing environment friendly approach. |
| A Glass of water : A Glass of water Properties
Liquid at room temp
Melts at 0 C
Boils at 100C
Dissolves many salts
Nonconductor of electricity |
| Toxicity : Toxicity Impact on environment |
| Green chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous materials : Green chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous materials |
| Risk!!!=HAZARD x exposure : Risk!!!=HAZARD x exposure |
| Axioms of green chemistry : Axioms of green chemistry Prevent waste
Atom economy
Avoid hazardous synthesis mode
Safer chemicals
Safer solvents and auxilleries
Energy efficiency
Renewable feedstock's
Reduce derivatives-convert to byproducts
Use catalysts wherever possible
Design for degradation
Incorporate pollution prevention
Accident prevention |
| RENEWABILITY : RENEWABILITY Petro-chemical feeds-an analysis |
| Usage of Ethyl Lactate solvent : Usage of Ethyl Lactate solvent ammonium lactate is thermally and catalytically cracked to produce the acid, which, with the addition of alcohol, is converted to the ester.
Use of catalysis and membrane technology in this method consumes less energy.
Ethyl lactate is made from corn feedstocks and so renewable
Process eliminates salt waste (gypsum) and undesirable by-products
This Green solvent replaces chlorine based solvents in many industries.
This synthesis is the contribution of Argonne national laboratory
U S A. |
| CATALYSTS USAGE : CATALYSTS USAGE Minimise wastes by using catalytic reactions
Catalysts work many cycles.
Stoichiometric reagents work once and must be avoided as much as possible |
| ATOM ECONOMY : ATOM ECONOMY Aim for 100% atom economy.
Final products aimed to contain a maximum proportion of the reactant atoms.
This will automatically reduce waste |
| Atom Economy calculation : Atom Economy calculation |
| Avoid chemical derivatives.Derivatives use additional reagents and generate waste.Use safer chemicals as solvents.Water is the best medium as solvent. : Avoid chemical derivatives.Derivatives use additional reagents and generate waste.Use safer chemicals as solvents.Water is the best medium as solvent. |
| Aim at high energy efficiency.If waste cannot be avoided then go in for the waste which is degradable.This will help in reducing pollution : Aim at high energy efficiency.If waste cannot be avoided then go in for the waste which is degradable.This will help in reducing pollution |
| Design chemicals and other reaction conditions to minimize the potential for chemical accidents like explosions, fires and release to environment. : Design chemicals and other reaction conditions to minimize the potential for chemical accidents like explosions, fires and release to environment. |
| Usage of catalysis wherever possible : Usage of catalysis wherever possible Pulp and paper industry example.
Bleaching was done with chlorine based chemicals.
Benign nontoxic Iron based catalyst used now.
Avoiding chlorine based bleaching agents makes it Greener.
Low temperature operation is advantageous.
Mechanism used is oxidation using peroxide.
Catalyst degradable and benign. |
| Viscose Industry : Viscose Industry In viscose industry depolymerisation step involved the usage of carbon di sulphide and sodium hydroxide.
Now radiation(electron beam) is used in this stage.This significantly reduced the amount of CS2 Na OH used- REDUCING POLLUTION
The conversion of cellulose to pulp is achieved in a green chemistry way.
This innovation was from B A R C and the beneficiary was GRASIM industries at NOIDA |
| Pioneering work attempted by Dr Sathiyamurthy and his group in B A RC : Pioneering work attempted by Dr Sathiyamurthy and his group in B A RC Dr Sathiyamurthy and his group are attempting to use supercritical carbon di oxide solvent in mettalurgical processes.
This involves generating high pressures of the order of 200 bars or so.
This is a very significant advancement in process mettalurgy-in the green chemistry way. |
| Environmental Impact Assessment and Green chemistry : Environmental Impact Assessment and Green chemistry EIA is a pollution management tool-Green chemistry is a pollution philosophy process.
EIA is required in final stages of implementation of a chemical process.
Green Chemistry involves designing of processes which are environmentally benign.
Hence Green chemistry is a far upstream process to EIA. |
| A green chemist will try to implement processes which are more efficient(fewer reaction steps,fewer resources required,less wastage) simpler to use(stable in air,at normal temperature and pressure) and environmentally benign. : A green chemist will try to implement processes which are more efficient(fewer reaction steps,fewer resources required,less wastage) simpler to use(stable in air,at normal temperature and pressure) and environmentally benign. |
| THANK YOU : THANK YOU |