Green Chemistry

Green Chemistry

It is well known fact that self-sufficiency in food has been achieved in India since late 20^th century by using fertilizers and pesticides and exploring improved methods of farming, good quality seeds, irrigation etc. But over exploitation of soil and excessive use of fertilizers and pesticides have resulted in the deterioration of soil, water and air.

The solution of this problem does not lie in stopping the process of development that has been set in; but to discover methods, which would help in the reduction of deterioration of the environment. Green chemistry is a way of thinking and is about utilizing the existing knowledge and principles of chemistry and other sciences to reduce the adverse impact on environment. Green chemistry is a production process that would bring about minimum pollution or deterioration to the environment. The byproducts generated during a process, if not used gainfully, add to the environmental pollution. Such processes are not only environmental unfriendly but also cost-ineffective. The waste generation and its disposal both are economically unsound. Utilization of existing knowledge base for reducing the chemical hazards along with the developmental activities is the foundation of green chemistry.  Have you perceived the idea of green chemistry? It is well known that organic solvents such as benzene, toluene, carbon tetrachloride etc., are highly toxic. One should be careful while using them.

As you know, a chemical reaction involves reactants, attacking reagents and he medium in which the reaction takes place. Extent of any reaction depends upon physical parameters like temperature, pressure and use of catalyst. In a chemical reaction, if reactants are fully converted into useful environmental friendly products by using an environment friendly medium then there would be no chemical pollutants introduced in the environment.

During a synthesis, care must be taken to choose starting materials that can be converted into end products with yield approximately up to 100 per cent. This can be achieved by arriving at optimum conditions of synthesis. It may be worthwhile to carry out synthetic reactions in aqueous medium since water has high specific heat and low volatility. Water is cost effective, noninflammable and devoid of any carcinogenic effects.

Green chemistry in day to day life

Dry Cleaning of Clothes : Tetra chlroroethene (Cl₂C=CCl₂) was earlier used as solvent for dry cleaning. The compound contaminates the ground water and is also a suspected carcinogen. The process using this compound is now being replaced by a process, where liquefied carbondioxide, with a suitable detergent is used. Replacement of halogenated solvent by liquid CO₂ will result in less harm to ground water.

These days hydrogen peroxide (H₂O₂) is used for the purpose of bleaching clothes in the process of laundry, which gives better results and makes use of lesser amount of water.

Bleaching of Paper: Chlorine gas was used earlier for bleaching paper. These days, hydrogen peroxide (H₂O₂) with suitable catalyst, which promotes the bleaching action of hydrogen peroxide, is used.

Synthesis of Chemicals: Ethanal (CH₃CHO) is now commercially prepared by one step oxidation of ethane in the presence of ionic catalyst in aqueous medium with a yield of 90%.

Green chemistry, in a nutshell, is a cost effective approach which involves reduction in material, energy consumption and waste generation.