Green chemistry , also called sustainable chemistry , is a chemical and chemical engineering field that focuses on designing products and processes that minimize the use and formation of harmful substances. While environmental chemistry focuses on the effects of chemical pollutants on nature, green chemistry focuses on the environmental impact of chemistry, including technological approaches to prevent pollution and reduce the consumption of non-renewable resources.
The overall goal of green chemistry - that is, more resource-efficient and inherently safer designs of molecules, materials, products, and processes-can be pursued in a variety of contexts.
Video Green chemistry
Histori
Green chemistry emerged from various ideas and research efforts (such as atomic economy and catalysis) in the period leading up to the 1990s, in the context of increasing attention to chemical pollution and resource depletion. The development of green chemistry in Europe and the United States is related to changes in environmental problem-solving strategies: a movement of command and control rules and the mandated reduction of industrial emissions on the "pipeline," to the active prevention of pollution through the innovative design of the production technology itself. A collection of concepts now recognized as a green chemistry united in the mid to late 1990s, along with a wider adoption of the term (which prevailed over competing terms like "clean" and "sustainable" chemistry).
In the United States, the Environmental Protection Agency plays a significant early role in encouraging green chemistry through its pollution prevention, funding, and professional coordination programs. At the same time in the UK, researchers at the University of York contributed to the formation of the Green Chemistry Network within the Royal Society of Chemistry, and the launch of the Green Chemistry journals.
Maps Green chemistry
Principles
In 1998, Paul Anastas (who later directed the Green Chemistry Program at US EPA) and John C. Warner (later of Polaroid Corporation) published a set of principles to guide the practice of green chemistry. These twelve principles discuss ways to reduce the environmental and health impacts of chemical production, and also indicate research priorities for the development of green chemical technology.
Its principles include concepts such as:
- process design to maximize the amount of raw material that ends in the product;
- use of renewable raw materials and energy sources;
- the use of safe and environmentally friendly substances, including solvents, whenever possible;
- energy efficient process design;
- avoids waste production, which is seen as the ideal form of waste management.
The twelve principles of green chemistry are:
- Prevention . Preventing waste is better than treating or cleaning up the waste after it is made.
- Economic atom. The synthetic method should try to maximize the incorporation of all the materials used in the process into the final product.
- Less harmful chemical synthesis . Synthetic methods should avoid using or producing toxic substances for humans and/or the environment.
- Designing safer chemicals. Chemical products should be designed to achieve the desired function while not as toxic as possible.
- More secure solvents and tools . Additional substances should be avoided wherever possible, and not dangerous when used.
- Design for energy efficiency . Energy requirements should be minimized, and the process should be carried out at ambient temperature and pressure whenever possible.
- Use of renewable raw materials . Whenever practical to do so, renewable raw materials or raw materials are better than non-renewable ones.
- Derive a descend . Generations of unnecessary derivatives - such as the use of protective groups - should be minimized or avoided where possible; Such steps require additional reagents and may generate additional waste.
- Catalysis . The catalytic reagents can be used in small amounts to repeat the reaction better than stoichiometric reagents (which are consumed in the reaction).
- Design for degradation . Chemical products should be designed so as not to pollute the environment; when their functionality is complete, they must break down into harmless products.
- Real time analysis for pollution prevention . Analytical methodologies need to be further developed to enable real-time monitoring and control in the process before harmful forms.
- Inherently safer chemistry for accident prevention . Whenever possible, substances in a process, and the forms of the substances, should be selected to minimize risks such as explosions, fires, and unintentional discharges.
Trends
Efforts are being made not only to measure the greenness of chemical processes but also for factors in other variables such as chemical yields, reaction component prices, chemical handling safety, hardware demands, energy profiles and ease of work and purification product. In one quantitative study, the reduction of nitrobenzene to aniline received 64 points from 100 marks as the overall accepted synthesis whereas the synthesis of amides using HMDS was only described as sufficient with a combined 32 points.
Green chemistry is increasingly being seen as a powerful tool that researchers must use to evaluate the environmental impact of nanotechnology. As nanomaterials are developed, the environmental and human health impacts of both the products themselves and the processes for making them should be considered to ensure their long-term economic viability.
Example
Green solvent
Solvents are consumed in large quantities in many chemical syntheses as well as for cleansing and removing fat. Traditional solvents are often toxic or chlorinated. Green solvents, on the other hand, generally come from renewable resources and biodegrade becomes harmless, often a natural product.
Synthetic techniques
Novels or improved synthetic techniques can often provide improved environmental performance or allow better adherence to green chemical principles. For example, the 2005 Nobel Prize in Chemistry was awarded to Yves Chauvin, Robert H. Grubbs and Richard R. Schrock, for the development of metathesis methods in organic synthesis, with explicit reference to its contribution to green chemistry and "intelligent production." The 2005 review identified three developments key in green chemistry in the field of organic synthesis: the use of supercritical carbon dioxide as a green solvent, aqueous hydrogen peroxide for clean oxidation and the use of hydrogen in asymmetric synthesis. Some further examples of applied green chemistry are supercritical water oxidation, in water reactions, and dry media reactions.
Bioengineering is also seen as a promising technique for achieving green chemical goals. A number of important process chemicals can be synthesized in engineered organisms, such as shikimate, Tamiflu precursors fermented by Roche in bacteria. Click chemistry is often referred to as a chemical synthesis style that is consistent with green chemical goals. The concept of 'green pharmacy' has recently been articulated on the basis of similar principles.
Carbon dioxide as blowing agent
In 1996, Dow Chemical won the Greener Reaction Condition Award 1996 for their 100% carbon dioxide blowing agent for the production of polystyrene foams. Polystyrene foam is a common material used in packing and food transportation. Seven hundred million pounds is produced annually in the United States alone. Traditionally, CFCs and other ozone-depleting chemicals are used in the production of foam sheets, which presents a serious environmental hazard. Flammable, explosive, and, in some cases toxic hydrocarbons have also been used instead of CFCs, but they present their own problems. Dow Chemical found that supercritical carbon dioxide works in conjunction with blowing agents, without the need for harmful substances, allowing polystyrene to be more easily recycled. CO 2 used in this process is reused from other industries, so the net carbon released from the process is zero.
Hydrazine
The principle of address # 2 is the Peroxide Process for producing hydrazine without salt-forming salts. Hydrazine is traditionally produced by the Olin Raschig process of sodium hypochlorite (an active ingredient in many bleaches) and ammonia. The net reaction produces one equivalent of sodium chloride for each equivalent of targeted product hydrazine:
- NaOCl 2 NH 3 -> H 2 N-NH 2 NaCl H 2 O
In a greener Peroxide process, hydrogen peroxide is used as an oxidant and the inferior product is water. The following net conversions:
- 2 NH 3 H 2 O 2 -> H 2 > 2 2 H 2 O
Addressing principle # 4, this process requires no additional extracting solvents. Methyl ethyl ketone is used as a carrier for hydrazine, the intermediate ketazine phase separating from the reaction mixture, facilitating the working without the need for extraction solvents.
1,3-Propanediol
The principle of address # 7 is the green route to 1,3-propanediol, traditionally produced from petrochemical precursors. This can be generated from renewable precursors through 1,3-propanediol bioseparation using genetically modified strains of E. coli . This diol is used to make new polyester for carpet making.
Lactide
In 2002, Cargill Dow (now NatureWorks) won the Environmentally Friendly Reaction Condition Award for their better method for polylactic acid polymerization. Unfortunately, the lactide-base polymer did not perform well and the project was stopped by Dow soon after the award. Lactic acid is produced by fermenting maize and converted into lactide, a cyclic dimer ester of lactic acid using efficiently catalyzed lead cyclization. The Enantiomer L, L-lactide is isolated by distillation and polymerized in the melt to create a crystallized polymer, which has several applications including textile and clothing, cutlery, and food packaging. Wal-Mart has announced that it uses/will use the PLA for its production packaging. The NatureWorks PLA process replaces renewable materials for petroleum raw materials, does not require the use of harmful organic solvents typical in other PLA processes, and produces high quality recyclable and compostable polymers.
Carpet tile support
In 2003 Shaw Industries chose a combination of polyolefin resin as the preferred base polymer for EcoWorx due to its low toxicity of raw materials, superior adhesion properties, dimensional stability, and its ability to be recycled. EcoWorx compounds should also be designed to be compatible with nylon carpet fibers. Although EcoWorx can be recovered from any type of fiber, nylon-6 provides a significant advantage. Polyolefin is compatible with the known method of depolymerization of nylon-6. PVC disrupts the process. Nylon-6 chemistry is well known and not addressed in first generation production. From the beginning, EcoWorx meets all the design criteria required to meet market needs from a performance, health, and environmental standpoint. Research shows that the separation of fiber and backing through elutriation, grinding, and air separation proves to be the best way to recover faces and supporting components, but the infrastructure to restore the postconsumer EcoWorx to the elutriation process is needed. Research also shows that post-sale carpet tiles have a positive economic value at the end of their useful life. EcoWorx is recognized by MBDC as a certified cradle-to-cradle design.
Fat transesterification
In 2005, Archer Daniels Midland (ADM) and Novozymes won the Greener Synthetic Preparation Prize for their enzyme interesterification process. Responding to the US Food and Drug Administration (FDA) mandated the labeling of trans-weight on nutritional information on January 1, 2006, Novozymes and ADM worked together to develop a clean, enzymatic process for interesterification of oils and fats by interchanging saturated and unsaturated fatty acids. The result is a commercially viable product without trans -fat. In addition to the human health benefits of eliminating trans-fats, the process has reduced the use of toxic chemicals and water, prevented a large number of byproducts, and reduced the amount of fat and oil wasted.
Bio-succinic acid
In 2011, the Extraordinary Green Chemical Award by the Small Business Award was awarded to BioAmber Inc. for the integrated production and downstream applications of bio-based succinic acid. Succinic acid is a platform chemical that is an important starting material in everyday product formulations. Traditionally, succinic acid is produced from petroleum-based feedstocks. BioAmber has developed processes and technologies that produce succinic acid from renewable feedstock fermentation at lower cost and lower energy expenditure than the petroleum equivalent while alienating CO 2 instead of emitting it.
Laboratory chemicals
Some controversial laboratory chemicals from a Green Chemical perspective. Massachusetts Institute of Technology created the "Green" Alternatives Wizard [2] to help identify alternatives. Ethidium bromide, xylene, mercury, and formaldehyde have been identified as the "worst offenders" with alternatives. Solvents in particular make a major contribution to the environmental impact of chemical manufacturing and there is a growing focus on the introduction of Greener solvents to the early stages of development of these processes: scale-laboratory reactions and refining methods. In the Pharmaceutical Industry, both GSK and Pfizer have published a Solvent Selection Guide for their Drug Discovery chemists.
Legislation
EU
In 2007, the EU implemented the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) Program, which requires companies to provide data indicating that their products are safe. This Regulation (1907/2006) ensures not only chemical hazard assessments and risks during its use but also includes measures to prohibit or restrict the use of certain substances. ECHA, the EU Chemical Agency in Helsinki, is currently enforcing its enforcement provisions located in EU member states.
United States
The US law that regulates most industrial chemicals (excluding pesticides, food, and pharmaceuticals) is the Toxic Substances Control Act (TSCA) of 1976. Examining the role of regulatory programs in shaping green chemical developments in the United States, analysts have revealed longstanding structural weaknesses and weaknesses in the TSCA; for example, a 2006 report to the California Legislature concluded that TSCA has produced a domestic chemical market that discounts hazardous chemicals relative to function, price and performance. Experts argue that such market conditions are a major deterrent to the scientific, technical and commercial success of green chemistry in the US, and fundamental policy changes are needed to correct this weakness.
Enacted in 1990, the Pollution Prevention Act helped develop a new approach to tackle pollution by preventing environmental problems before they occur.
In 2008, the State of California approved two laws aimed at encouraging green chemistry, launching the California Green Chemistry Initiative. One of these laws requires the California Toxic Danger Inspection Department (DTSC) to develop new regulations to prioritize "chemicals of concern" and promote the substitution of hazardous chemicals with safer alternatives. The current regulation comes into effect in 2013, initiating the DTSC Safe Consumer Products Program .
Education
Many institutions offer courses and degrees at Green Chemistry. Examples from around the world are the Danish Technical University, and some in the US, e.g. at the Universities of Massachusetts-Boston, Michigan, and Oregon. The master's degree course at Green Technology, has been introduced by the Institute of Chemical Technology, India. In England at the University of York University of Leicester, Department of Chemistry and MRes at Green Chemistry at Imperial College London. In Spain, different universities such as Universidad de Jaume I or Universidad de Navarra, offer master courses of Green Chemistry. There are also websites that focus on green chemistry, such as Michigan Green Chemistry Clearinghouse at www.migreenchemistry.org. Apart from the subjects of his Chemistry of Green Chemistry, the University of Zurich, ZHAW, ZHAW Science presents the exposition and web pages "Making green chemistry" for the wider public, which illustrates 12 principles.
Scientific journal green chemistry
- Green Chemistry (RSC)
- Green Chemistry Letters and Review (Open Access) (Taylor & Francis)
- ChemSusChem (Wiley)
- ACS Sustainable & amp; Technique (ACS)
The contested definition
There is ambiguity in the definition of green chemistry, and how it is understood among the broader sciences, policies, and business community. Even in chemistry, researchers have used the term "green chemistry" to describe work independently of the framework proposed by Anastas and Warner (ie, 12 principles). While not all of the terms used are valid (see greenwashing), many of which, and the authoritative status of a single definition are uncertain. More broadly, the idea of ​​green chemistry can easily be attributed (or confused) to related concepts such as green techniques, environmental design, or general sustainability. The complexity and multifaceted nature of green chemistry make it difficult to construct clear and simple metrics. As a result, "what's green" is often open to debate.
Awards
Several scientific societies have created awards to encourage research in green chemistry.
- The Australian Green Chemistry Challenge Award is overseen by The Royal Australian Chemical Institute (RACI).
- Canadian Green Chemistry Medal.
- In Italy, the Green Chemistry center is located around an inter-university consortium known as INCA.
- In Japan, The Green & amp; The Sustainable Chemistry Network oversees the GSC award program.
- In the UK, Green Chemical Technology Awards are awarded by Crystal Faraday.
- In the US, the Green Chemistry Challenge Awards Presidents recognize individuals and businesses.
See also
- Bioremediation - a technique that is generally outside the green chemistry sphere
- Environmental engineering sciences
- Green Chemistry (journal) - published by the Royal Society of Chemistry
- Green chemical metrics
- Green computing - a similar initiative in the computing field
- Green engineering
- Substitution of hazardous chemicals
- Continuous engineering
References
Source of the article : Wikipedia
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