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green chemistry


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green chemistry

  1. 1. Green Chemistry and its Role for Sustainability As A branched topic of the UNESCO conference on ESD Bonn, Germany, 2009 Presenter: Dr. Zeinab Shaaban Abu-Elnaga Faculty of Science Mansoura University Egypt 2009
  2. 2. Learning 0bjectives To conceptualize the sustainability and ESD To understand how to apply this concept in our research fields of interest aiming to safe our plant To think prospectively about how to change our education subjects to be sustainable learning tools by Investigating examples of green chemistry applications relevant to students To understand the important role of the green chemistry and how to deal with it in our practical life The topic is very vast but I have tried to cover it in one lecture and I will give the links for more details of each sub-topic 2009
  3. 3. Performance Objectives: To understand the importance of Green chemistry for sustainability To design and interpret greener route to the traditional chemical reactions To learn how to teach green chemistry as a lab course 2009
  4. 4. Sustainability • Meeting the needs of the present generation without compromising the needs of future generations • Green chemistry: technologies of the invention, design and application of chemical products and processes to reduce or to eliminate the use and generation of hazardous substances ,and where possible utilize renewable raw materials Primary pollution prevention not remediation Use of chemistry for improved environmental performance Is the goal is the means
  5. 5. As human beings --- we are part of the environment The way in which we interact with our environment influences the quality of our lives Green Chemistry A tool Industrial ecology Sustainable development the goal Green chemistry, lies at the heart of the industrial ecology 2009
  6. 6. Green chemistry, is called also Benign chemistry or clean chemistry for sustainability • Refers to the field of chemistry dealing with 1- Synthesis (the path to making chemicals) 2- Processing (the actual making of chemicals) 3- Use of chemicals that reduce risks to humans and impact on the environment Green chemistry education: A key to sustain the development of new educational materials
  7. 7. Green Chemistry Is About... Cost Waste Materials Hazard Risk Energy 2009
  8. 8. Principles of Green Chemistry Prevent waste. Design safer chemicals and products. Design less hazardous chemical syntheses. Use renewable feed stocks. Use catalysts, not stoichiometric reagents: Catalysts are used in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once. Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. generate waste. Maximize atom economy. Use safer solvents and reaction conditions Increase energy efficiency. Design chemicals and products to degrade after use. Analyze in real time to prevent pollution. Minimize the potential for accidents. Originally published by Paul Anastas and John Warner in Green Chemistry: Theory and Practice (Oxford University Press: New York, 1998). 2009
  9. 9. Now, how can we deal with green chemistry at our practical life Just we need to change our mind set and applying the concept in Classrooms laboratory manufacture And finally the surrounding environment
  10. 10. O3 or supercritical water oxidation • If the chemical reaction of the type • A + B P + W • Find alternate A or B to avoid W • Example 1: • Disinfection of water by chlorination. Chlorine oxidizes the pathogens there by killing them, but at the same time forms harmful chlorinated compounds. • A remedy is to use another oxidant, such as 2009
  11. 11. Example 2 of green chemistry • Production of allyl alcohol CH2=CHCH2OH • Traditional route: Alkaline hydrolysis of allyl chloride, which generates the product and hydrochloric acid as a by-product • Greener route, to avoid chlorine: Two-step using propylene (CH2=CHCH3), acetic acid (CH3COOH) and oxygen (O2) • Added benefit: The acetic acid produced in the 2nd reaction can be recovered and used again for the 1st reaction, leaving no unwanted by-product. CH2=CHCH2Cl + H2O CH2=CHCH2OH + HCl problem product CH2=CHCH2OCOCH3 + H2O CH2=CHCH2OH + CH3COOH CH2=CHCH3 + CH3COOH + 1/2 O2 CH2=CHCH2OCOCH3 + H2O 2009
  12. 12. Example 3 of green chemistry • Production of styrene (=benzene ring with CH=CH2 tail) • Traditional route: Two-step method starting with benzene, which is carcinogenic) and ethylene to form ethylbenzene, followed by dehydrogenation to obtain styrene • Greener route: To avoid benzene, start with xylene (cheapest source of aromatics and environmentally safer than benzene). • Another option, still under development, is to start with toluene (benzene ring with CH3 tail). + H2C=CH2 catayst CH2CH3 ethylbenzene catayst CH=CH2CH2-CH3 ethylbenzene styrene 2009
  13. 13. Green chemistry education Chemistry students need to be encouraged to consider the principles of green chemistry when designing processes and choosing reagents Interactive Teaching Units (ITU) have been developed specifically to introduce undergraduate students to green chemistry There are numerous scholarships and grants available for researchers and young scholars who are furthering the goals of green chemistry 2009
  14. 14. conclusion Green Chemistry:Green Chemistry: Preventing Pollution Sustaining the Earth Green chemistry has come a long way since its birth in 1991, growing from a small grassroots idea into a new approach to scientifically-based environmental protection All over the world, governments and industries are working with “green” chemists to transform the economy into a sustainable enterprise Who knows? Green chemistry may be the next social movement that will set aside all the world’s differences and allow for the creation of an environmentally commendable civilization 2009
  15. 15. References 2009