Green-chemistry - Lecture notes 5 PDF

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EVS green chemistry lecture notes...

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GREEN CHEMISTRY INTRODUCTION:-

Green chemistry, also called sustainable chemistry, is an area of chemistry and chemical engineering focused on the design of products and processes that minimize the use and generation of hazardous substances. Whereas environmental chemistry focuses on the effects of polluting chemicals on nature, green chemistry focuses on technological approaches to preventing pollution and reducing consumption of nonrenewable resources. Green chemistry overlaps with all sub disciplines of chemistry but with a particular focus on chemical synthesis, process chemistry, and chemical engineering, in industrial applications. To a lesser extent, the principles of green chemistry also affect laboratory practices. The overarching goals of green chemistry—namely, more resource-efficient and inherently safer design of molecules, materials, products, and processes—can be pursued in a wide range of contexts.

THE TWELVE BASIC PRINCIPLES OF THE GREEN CHEMISTRY ARE: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. Use of Renewable Feedstock’s A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable.

8. Reduce Derivatives Unnecessary derivatization (use of blocking groups, protection/deprotection, and temporary modification of physical/chemical processes) should be minimised or avoided if possible, because such steps require additional reagents and can generate waste.

9. Catalysis Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.

10. Design for Degradation Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment.

11. Real-time Analysis for Pollution Prevention Analytical methodologies need to be further developed to allow for realtime, in-process monitoring and control prior to the formation of hazardous substances.

12. Inherently Safer Chemistry for Accident Prevention : Substances and the form of a substance used in a chemical process should be chosen to minimize the potential for chemical accidents, including releases, explosions, and fire.

THE R4M4 PRINCIPLES:The four R principles are:1.) Recycle- is a process to convert waste materials into new products to

prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution (from incineration) and water pollution (from landfilling) by reducing the need for "conventional" waste disposal and lower greenhouse gas emissions as compared to plastic production.

2.)

Reuse-To reuse is to use an item again after it has been used. This includes conventional reuse where the item is used again for the same function, and creative reuse where it is used for a different function. In contrast, recycling is the breaking down of the used item into raw materials which are used to make new items. By taking useful products and exchanging those, without reprocessing, reuse help save time, money, energy, and resources. In broader economic terms, reuse offers quality products to people and organizations with limited means, while generating jobs and business activity that contribute to the economy.

3.)

Reduce:-Reducing isn't only good for the environment. It is also good for your budget. Do you need that thing you're considering buying? Maybe you'd really be better off without it? You'd probably have more money for other things (vacation?), you wouldn't have to store and take care of it? Would you be better off borrowing, renting, or sharing it? Sometimes friends or neighbors can save money and space by buying and sharing some things that they only need occasionally (perhaps a carpet cleaner or circular saw).

4.)

Redesign: - Redesigning the environment means process of addressing surrounding environmental parameters when devising plans, programs, policies, buildings, or products. Classical prudent design always considers environmental factors.

The four M principles are:-

1.) Multiscanning: - Multiscanning is running multiple anti-malware or antivirus engines concurrently. Traditionally, only a single engine can actively scan a system at a given time. Using multiple engines simultaneously can result in conflicts that lead to system freezes and application failures. However, a number of security applications and application suites have optimized multiple engines to work together. 2.) Multitasking: - Human multitasking is the apparent performance by an individual of handling more than one task, or activity, at the same time. The term is derived from computer multitasking. An example of multitasking is taking phone calls while typing an email. 3.) Multifaced: - Environmental changes are frequent but their shape and character depends on the knowledge & experience of the observer. A particular change in the environment may be viewed differently by different businessmen. This change is welcomed as an opportunity by some organizations while some others take it as a threat for their survival.

4.) Multidimensional: - An organization is multidimensional if its objectives are pursued simultaneously through multiple dimensions (product, region, account, market segment).The multidimensional organization was discussed as early as the 1970s. It required the combination of the fall of costs of information, the development of dynamic multidimensional markets, and a new generation of workers and managers, to create this paradigm shift in organization forms.

The multidimensional organization exhibits the following:1. the overall performance of the firm is reported simultaneously on multiple dimensions and on multiple levels; 2. each of these dimensions has a manager who is held accountable for the contribution of his dimension to the overall performance; 3. these managers depend on each other for required resources; and 4. These managers collectively are accountable for the overall performance....