Green chemestry 11th science
- 2. GREEN CHEMISTRY DEFINITION Green Chemistry is the utilisation of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture and application of chemical products . GREEN CHEMISTRY IS ABOUT • Waste Minimisation at Source • Use of Catalysts in place of Reagents • Using Non-Toxic Reagents • Use of Renewable Resources • Improved Atom Efficiency • Use of Solvent Free or Recyclable Environmentally Benign Solvent systems
- 3. Why do we need Green Chemistry ? • Chemistry is undeniably a very prominent part of our daily lives. • Chemical developments also bring new environmental problems and harmful unexpected side effects, which result in the need for ‘greener’ chemical products. • A famous example is the pesticide DDT.
- 4. Reduction by green Chemistry Cost Waste Materials Hazard Risk Energy
- 5. • Green chemistry looks at pollution prevention on the molecular scale and is an extremely important area of Chemistry due to the importance of Chemistry in our world today and the implications it can show on our environment. • The Green Chemistry program supports the invention of more environmentally friendly chemical processes which reduce or even eliminate the generation of hazardous substances. • This program works very closely with the twelve principles of Green Chemistry.
- 6. The 6 Principles of Green Chemistry 1. Prevention It is better to prevent waste than to treat or clean up waste after it has been created. 2. Atom Economy Synthetic methods should be designed to maximise the incorporation of all materials used in the process into the final product. 3. Less Hazardous Chemical Synthesis Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to people or the environment. 4. Designing Safer Chemicals Chemical products should be designed to effect their desired function while minimising their toxicity. 5. Safer Solvents and Auxiliaries The use of auxiliary substances (e.g., solvents or separation agents) should be made unnecessary whenever possible and innocuous when used. 6. Design for Energy Efficiency Energy requirements of chemical processes should be recognised for their environmental and economic impacts and should be minimised. If possible, synthetic methods should be conducted at ambient temperature and pressure.
- 7. “The use of auxiliary substances (e.g. solvents, separation agents, etc.) should be made unnecessary wherever possible, and innocuous when used”
- 8. EXAMPLES OF GREEN CHEMISTRY • Safer dry cleaning • Initially gasoline and kerosene were used • Chlorinated solvents are now used, such as perc • Supercritical/liquid carbon dioxide (CO2)
- 9. GREEN CHEMISTRY SUPPORTS SUSTAINABILITY BY: • Making chemicals safe for our health & environment, • Using industrial processes that reduce or eliminate hazardous chemicals, & • Designing more efficient processes that minimize waste
- 10. “Energy requirements should be recognized for their environmental impacts and should be minimized. Synthetic methods should be conducted at ambient pressure and temperature”
- 11. Alternative Reaction Conditions • Reduce or eliminate solvents used in reaction media, separations, formulations • use of supercritical fluids as solvents • able to tune supercritical fluids by choosing critical region to conduct chemistry • Use aqueous solvent systems in place of organic solvents in chemical manufacturing • Use Supercritical CO2 as a solvent • Reduce operating temperatures • Must evaluate impact on case by case basis
- 12. “Although the positive contributions of chemistry and the chemical industry are many, some pollution problems have also resulted. Many of these problems can now be solved”. 12
- 13. The major uses of GREEN CHEMISTRY Energy Resource Depletion Food Supply
- 14. Energy Green Chemistry will be essential in Developing the alternatives for energy generation (photovoltaics, hydrogen, fuel cells, biobased fuels, etc.) as well as Continue the path toward energy efficiency with catalysis and product design at the forefront.
- 15. Resource Depletion Renewable resources can be made increasingly viable technologically and economically through green chemistry.
- 16. Food Supply Green chemistry is developing: Pesticides which only affect target organisms and degrade to innocuous by-products. Fertilizers and fertilizer adjuvants that are designed to minimize usage while maximizing effectiveness. Methods of using agricultural wastes for beneficial and profitable uses.
- 18. Conclusion Green chemistry Not a solution to all environmental problems But the most fundamental approach to preventing pollution.
- 19. Thank you