What is Green chemistry?

In the early 1990s, at the initiative of the Clinton administration, the Department of toxicology and pollution prevention of the U.S. environmental Protection Agency (U.S. EPA Office of Pollution Prevention and toxins) organized activities under the President's Green chemistry Program. The interaction between the development of the US environmental Protection Agency and sustainable development technologies has led to the emergence of the concept of "Green chemistry", which is a kind of philosophy. While many national and international programs are aimed at preventing pollution and solving environmental problems, green chemistry places a unique emphasis on preventing pollution at the very initial stages of planning and implementing chemical processes.

Green chemistry is a fundamentally new innovative approach to reducing or eliminating the use of dangerous and toxic chemicals. Green chemistry is a fundamentally new approach to solving environmental problems, using clean and less polluting industrial processes and ensuring that manufacturers take responsibility for the products they produce.

Thus, carrying out chemical processes in accordance with the principles of green chemistry is considered both from the point of view of obtaining the necessary substances and consumer goods, and possible consequences for public health and the environment.

12 principles of Green chemistry.

Explain each of these principles.

In 1998, P. Anastas and j.Warner, in his book" Green chemistry: Theory and practice " [Anastas, P. T.; Warner, J. C. Green Chemistry: Theory and Practice, Oxford University Press: New York, 1998] formulated 12 principles of Green chemistry. These principles reflect the activities of the scientific community, industry, and government agencies aimed at reducing or eliminating the use of hazardous materials and chemical processes.

1. It is better to prevent losses than to recycle and clean waste.
2. Synthesis methods should be chosen in such a way that all the materials used in the process are maximally translated into the final product.
3. If possible, the synthesis methods should be chosen so that the substances used and synthesized are as little harmful to humans and the environment as possible.
4. When creating new chemical products, we must try to maintain the performance achieved earlier, while reducing the toxicity.
5. Excipients in production, such as solvents or separating agents, should not be used at all, and if this is not possible, their use should be harmless.
6. Be sure to take into account energy costs and their impact on the environment and the cost of the product. If possible, the synthesis should be carried out at a temperature close to the ambient temperature and at atmospheric pressure.
7. Raw materials and consumable materials must be renewable in all cases where it is technically and economically profitable.
8. Where possible, it is necessary to avoid obtaining intermediate products (block groups, attaching and removing protection, etc.).
9. Preference should always be given to catalytic processes (as selective as possible).
10. The chemical product must be such that it does not remain in the environment after use, but decomposes into safe products.
11. We need to develop analytical techniques so that we can monitor the formation of dangerous products in real time.
12. Substances and forms of substances used in chemical processes should be selected in such a way that the risk of chemical hazards, including leaks, explosion and fire, is minimal.

The Green chemistry approach involves a large number of factors for evaluating an industrial process, such as the cost of reagents, equipment, and labor; the cost of recycling waste and by-products, processing and cleaning reagents and the target product; the cost of transportation; providing storage and special equipment; the cost of providing additional precautions, and many others. Of course, if we consider each of these factors separately, it may sometimes seem that compliance with the principles of green chemistry only increases the cost of the process. For example, a large proportion of heterogeneous catalysts contain expensive noble metals. However, increasing the selectivity of the chemical process automatically reduces the cost of waste treatment and disposal. As a result, the total cost of the process will often be lower, despite the expensive cost of the catalyst.
The same reasoning is true for principle 3, which States that synthesis Methods should be chosen as far as possible so that the substances used and synthesized are as little harmful to humans and the environment as possible. The use of even non-toxic compounds significantly increases the cost of the process, starting from the stage of their purchase, the cost of transportation, storage and special equipment, the cost of providing additional precautions, etc. The transition in chemical technologies to non-toxic reagents is undoubtedly beneficial both from an environmental and economic point of view.

What are renewable resources and why are they more efficient to use in terms of green chemistry?

One of the principles of Green chemistry is related to the use of renewable resources instead of fossil resources. Today, it is no secret that the planet's fossil resources are being depleted. In this regard, there is a need to move to those resources that can be replenished. More strictly speaking, renewable natural resources are those resources that either recover faster than they are used (or their recovery rate is comparable to the rate of expenditure), or do not depend on whether they are used or not. For example, renewable natural resources include plant raw materials (wood, cereals, etc.). Some resources that are classified as renewable are not actually being restored and will eventually be exhausted. These include, for example, solar and geothermal energy. The" green " direction of development of the chemical industry is the synthesis of fuel from renewable biological raw materials (biofuels). To date, there are a large number of projects on this topic that offer processing of sugar cane stalks or rape seeds, corn, and soy.

What is biodiesel?

Today, the main types of "vegetable" fuel used for gasoline engines are biodiesel and bioethanol. The latter is produced from sugar beet, wheat, corn and sugar cane. In fact, this is an ordinary alcohol, in the manufacture of which for energy needs, of course, there are technological features.

As an automobile fuel, ethanol is superior to gasoline in some respects. It has much less impurities (for example, sulfur), and the octane number according to the research method reaches 125 units. However, it is not yet possible to fill most production cars with bioethanol in its pure form. Therefore, ethanol is sometimes used as a high-octane additive in conventional gasoline, and the corresponding fuel is marked with the letter E, for example, the marking of gasoline E10 (10% ethanol). The most widespread biofuels are found in Brazil, where fossil reserves are small, but the climate is quite conducive to growing plant materials. Another advantage of biofuels is considered to be the reduction of greenhouse gas emissions. Of course, this does not mean that the combustion of biofuels produces less carbon dioxide. When biofuels are burned, carbon that was previously absorbed by plants is returned to the atmosphere, so the planet's carbon balance remains unchanged. At the same time, when burning fossil fuels, "canned" carbon enters the atmosphere.
Water is a "universal solvent".

Why is it not considered a more environmentally friendly solvent than CO2?

As controversial as it may seem, water is not one of the most" green " solvents. The solubility of compounds in water is usually higher than, for example, in CO2. As a result, the risk of environmental pollution increases if such polluted water is released into the atmosphere.

Resources:
http://www.greenchemistry.ru/popularization/gordon.htm
http://www.greenchemistry.ru/popularization/golubina.htm

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