Understanding The Concepts Of Green Chemistry Environmental Sciences Essay

Our environment, which is endowed by nature, needs to be protected from ever increasing chemical pollution associated with contemporary lifestyles and emerging technologies. India, 2nd largest producer of pesticides and ranked 12th in pharmaceutical production, is fast emerging as top 5 player in selected petrochemicals. The challenge for the institution and industries is to come together and pursue development in the field of greener chemistry by reducing or eliminating the use and generation of hazardous substances. We have organized a national and an international symposium for promoting Green Chemistry in India, which has provided the platform for interaction of concepts among the leading scientist. Moreover a refresher course of three weeks for college teachers on eco-friendly chemistry has also been organized earlier to promote awareness and facilitate education training and the practice of green chemistry in academic institutions. The main idea behind is to activate work towards green chemistry for which involvement of academic, industrial, governmental and non-governmental bodies is needed collectively which will help the designing and development of environment friendly chemistry practices in India.

Contents

Introduction.

Principles of green chemistry.

Sustainable development.

Atom economy.

Reactions in green chemistry.

Reducing toxicity.

Green analytical chemistry.

What can green chemistry do?

Why green chemistry?

What is the role of chemist in green chemistry?

Graph of published articles in journals.

Examples of green chemistry.

Examples of investigatory projects in green chemistry

Future products.

Some basic ways in which we go about green product development.

Values of green chemistry in innovation, application and technology: Indian Scenario.

Some recent developments and examples in green chemistry.

Government initiatives.

Introduction

Green chemistry: – Green chemistry may be defined as the invention ,design ,and application of chemical product and process to reduce the eliminate the use and generation of hazardous substances.

Therefore, green chemistry is a tool not only for minimizing the negative impact of those procedures aimed at optimizing efficiency, although clearly both impact minimization and process optimization are legitimate and complementary objectives of the subject.

Green chemistry, however, also recognizes that there are significant consequences to the use of hazardous substances, ranging from regulatory, handling and transport, and liability issues, to name a few. To limit the definition to deal with waste only, would be to address only part of the problem.

Green chemistry is applicable to all aspects of the product life cycle as well. 

Finally, the definition of green chemistry includes the term “hazardous”. It is important to note that green chemistry is a way of dealing with risk reduction and pollution prevention by addressing the intrinsic hazards of the substances rather than those circumstances and conditions of their use that might increase their risk.

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Green chemistry is not complicated although it is often elegant. Green chemistry applies to any type of chemistry such as organic chemistry, inorganic chemistry, bio chemistry, analytical chemistry and even physical chemistry. Green chemistry is mainly for industrial area. The main goal of green chemistry is to minimizing the hazard and maximizing the efficiency of any chemical choice.

Green chemistry can be applies on organic chemistry, physical chemistry, inorganic chemistry, analytical chemistry and biochemistry. Mainly green chemistry focuses on industrial applications. The main goal of green chemistry is to minimizing the hazard and maximizing the efficiency of any chemical choice.

Principles of green chemistry:-

There are twelve principles of green chemistry.

It is better to prevent waste than to treat or clean up waste after it is formed.

Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.

Wherever practicable, synthetic methodologies should be designed to use and generate substances that possess little or no toxicity to human health and the environment.

Chemical products should be designed to preserve efficacy of function while reducing toxicity.

The use of auxiliary substances (solvents, separation agents, etc.) should be made unnecessary whenever possible and innocuous when used.

Energy requirements should be recognized for their environmental and economic impacts and should be minimized. Synthetic methods should be conducted at ambient temperature and pressure.

A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable.

Unnecessary privatization (blocking group, protection/ deprotection, temporary modification of physical/chemical processes) should be avoided whenever possible.

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

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

Analytical methodologies need to be further developed to allow for real time, in-process monitoring and control before the formation of hazardous substances.

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 fires.

The term Green Chemistry, coined by staff at the US EPA in the 1990s, helped to bring focus to an increasing interest in developing more environmentally friendly chemical processes and products.

An evaluation of how green a chemical reaction or a chemical process is seems to be best done in terms of the 12 principles that have been advocated by Anastas and Warner. These tenets deal with fundamental issues such as pollution prevention, atom economization and toxicity reduction. The essence of the 12 principles may be summarized as follows:

Waste prevention instead of waste clean-up, atom economy as an important concern, design of environmentally friendly synthetic methodologies, design of safer chemicals, redundancy of auxiliary substances, conservation of energy, use of renewable feedstock, reduction of unnecessary derivatization , catalytic reactions instead of stoichiometric ones, debasement of final products after the end of their function, real-time analysis for pollution prevention and strategies for chemical accident prevention.

Sustainable development-

Sustainability in science and technology begins when we start thinking how to solve a problem or how to turn science into technology. Chemistry, as the science of matter and its transformation, plays a central role in this process and is the bridge between physics, material sciences and life sciences. Only chemical processes, which have reached – after careful optimization – a maximum in efficiency, will lead to more sustainable products and production. Scientists and engineers, who invent, develop and optimize such processes, therefore play a key role. Their awareness, creativity and looking ahead is needed to bring reactions and chemical processes to maximum efficiency. The term “Green Chemistry” has been coined for efforts towards this goal.

Atom economy:-

Atom economy means maximizing incorporation of material from the starting materials or reagents into the final products. It is essentially pollution prevention at molecular level.

For example, a chemist practicing atom economy would choose to synthesis a needed product by putting together basic building blocks, rather than by breaking down a much larger starting material and discarding most of it waste.

Atom economy is an important development beyond the traditionally taught concept of percent yield. Barry Trost, from Stanford University, published the concept of atom economy in science in 1991. In 1998 received the president green chemistry challenged award for his work.

Atom economy answers the basic question, “how much of what you put into your pot end up in your product”.

Calculation of Atom Economy

Reactions in green chemistry-

There are two types of reactions-

Atom economic reactions.

Atom un-economic reactions.

In atom economic reactions there are another two type reactions

Rearrangement reactions.

Addition reactions.

In atom un-economic reaction there are three type of reactions

Substitution reaction.

Elimination reaction.

Witting reaction.

Reducing toxicity-

One of the underpinning principle of green chemistry is to design chemical product and process that use and produce less hazardous materials. Here hazardous cover all aspects, including toxicity, flammability, explosion potential, and environmental persistence.

A hazard can be defined as situation that may lead to harm, whilst risk is the probability that harm will occur. From the point of view harm being caused by exposure to the chemical.

Risk =

Green analytical chemistry-

The relationship between green chemistry and analytical chemistry can be treated in two ways. Analytical chemistry is a subject to control and justify green chemistry. This is where analytical chemistry is an efficient tool for confirmation of the green result of a chemical product or technology. On the other hand, chemical analysis methods need solvents, reagents, and energy, and they generate waste. The principles of green chemistry, suggested by Anastas and Warner, are directly related to analytical chemistry as well, the most important of them being

prevention of waste generation;

safer solvents and auxiliaries;

design for energy efficiency; and

Safer chemistry to minimize the potential of chemical accidents.

In this way, analytical chemistry becomes an object of application of the principles of green

Chemistry, and can be the target of a green chemistry approach similarly to other areas of chemistry and chemical technology. The term “green analytical chemistry” has been proposed by J. Namies´nik in that several aspects of making analytical chemistry greener were discussed.

The development of instrumental methods to replace wet chemistry in sample preparation and

treatment is a general trend in analytical chemistry. Here, the main analytical result is related to an increase of analysis reliability, higher precision, and time saving, which very positively combines with a substantial reduction of waste. In most cases, the result of instrumental methods in analysis is a decrease in sample volume needed for analysis. Special efforts to integrate micro fluidics and processing in micro scale can substantially decrease the sample amount and accompanying generation of waste.

In some cases, there is a choice of direct techniques of analysis (different laser-spectroscopic methods) or solvent less processes of analysis, which are green processes. However, in most cases, the samples under study are very complicated mixtures with interfering matrices not allowing the use of waste less method.

The search for alternative solvents is an important step on the way of using greener methods. In

This process, the main target should be not just the replacement, but introduction of an additional advantage from different properties of these solvents to improve the selectivity, sensitivity, and reliability of analysis, as well as reduce analysis time.

The development of instrumental methods in general leads to an efficient use of energy, especially when the method is highly automated and uses a minimal amount of sample. The hyphenation of several methods for sample treatment and separation of components or integration of separation and complicated methods of detection enables an efficient use of energy. Additional energy saving is possible when a microwave treatment or even just microwave heating is incorporated into the process. An ultrasonic irradiation may also have a strong effect on several sample treatments. The development of photochemical methods is a highly green way in analytical chemistry as well.

Most of the above-mentioned procedures also result in safer chemistry. In many cases of sample preparation and treatment, different chemical methods for derivatization and chemical modification of samples are still used. The search for less toxic compounds and processes with reduced waste generation should be an aim in the development of new methods.

What can green chemistry do?

Green chemistry is not a particular set of technologies, but rather an emphasis on the design of chemical products and processes.  Sometimes, green chemistry takes place at the molecular level to reduce or eliminate the use and generation of hazardous substances. This approach offers environmentally beneficial alternatives to more hazardous chemicals and processes, and thus promotes pollution prevention.

Green chemistry can lead to dramatic changes in how we interact with chemicals on a daily basis as in the case of the 2005 Nobel Prize in Chemistry for the development of the metathesis method in organic synthesis. “The word metathesis means ‘change-places’.

In metathesis reactions, double bonds are broken and made between carbon atoms in ways that cause atom groups to change places. This happens with the assistance of special catalyst molecules. Metathesis can be compared to a dance in which the couples change partners. Metathesis is used daily in the chemical industry, mainly in the development of pharmaceuticals and of advanced plastic materials. Thanks to the Laureates’ contributions, synthesis methods have been developed that are

more efficient (fewer reaction steps, fewer resources required, less wastage),

simpler to use (stable in air, at normal temperatures and pressures), and

Environmentally friendlier (non-injurious solvents, less hazardous waste products).

This represents a great step forward for ‘green chemistry’, reducing potentially hazardous waste through smarter production. Metathesis is an example of how important basic science has been applied for the benefit of man, society and the environment.”

The main question is that

Why Green Chemistry?

Green chemistry is effective in reducing the impact of chemicals on human health and the environment. In addition, many companies have found that it can be cheaper and even profitable to meet environmental goals. Profits derive from higher efficiency, less waste, better product quality, and reduced liability.

Many environmental laws and regulations target hazardous chemicals, and following all these requirements can be complicated. But green chemistry allows companies to comply with the law in much simpler and cheaper ways. Finally, green chemistry is a fundamental science-based approach. Addressing the problem of hazard at the molecular level, it can be applied to all kinds of environmental issues.

Since 1991, there have been many advances in green chemistry, in both academic research and industrial implementation. For example, Spinosad , an insecticide manufactured by fermenting a naturally occurring soil organism, was registered by the EPA as a reduced-risk insecticide in 1997. Spinosad does not leach, bioaccumulation, volatilize, or persist in the environment and in field tests left 70 to 90 percent of beneficial insects unharmed. It has a relatively low toxicity to mammals and birds and is slightly to moderately toxic to aquatic organisms, but is toxic to bees until it dries. In another advance, an industrial cleaning solvent, ethyl lactate, made from cornstarch and soybean oil was patented in 2000 and is competitively priced with petrochemical solvents. It biodegrades to carbon dioxide and water and has no known harmful effects for the environment, humans, or wildlife. These advances, however, represent an extremely small fraction of the potential applications of green chemistry. Because the products and processes that form the basis of the economy and infrastructure are based on the design and utilization of chemicals and materials, the challenges facing this field are enormous.

What is the role of chemist in green chemistry?

Chemist can use his knowledge of green chemistry and its benefits to justify research into ‘cleaner and greener’ process. In most cases it is readily demonstrable that green chemistry approach involving reduction of waste, material and energy, will also lead to cost reductions and that this in turn will have a positive effect on profitability. In academia initiatives such as the engineering and physical sciences research council (EPSRC) Clean Technology Programme and the government’s sustainable technology initiative have already encouraged professionals to enter this area.

Although many of the technologies or tools required to make chemical manufacturing more sustainable are available, and indeed industry already making significant progress , much more can be achieved. In order to move forward chemist need to understand, and overcome the barrier s, both real and perceived, that exist to innovation in this area. In some cases a culture change may be required before the potential financial benefits are fully appreciated. Professional chemist also have a major role in helping to encourage all interested parties, including industry, customers, pressure groups, government, educationalist and researchers, to co-operate to ensure a cleaner and more sustainable future.

Graph of published articles in journals-

Examples of green chemistry-

Lead-free solders and other products- Breakthroughs in the replacement of lead include use of new soldering materials, alternatives to lead additives in paint and the development of cleaner batteries.

Bioplastics – Plastics made from plants, including corn, potatoes or other agricultural products, even agricultural waste, are an important example of green chemistry. Products already available are forks, knives and spoons made from potato starch and biodegradable packaging made from corn. Flame resistant materials-Plastics that do not require the use of flame retardants are a solution to the problem of toxic flame retardants. A combination of polylactic acid and kenaf-two agriculturally products-has already been developed for this purpose.

Halogen-free flame retardants- For products that still require the use of flame retardants, green chemistry can help identify new, less toxic alternatives. For example, silicone based materials can be used.

Biopesticides also the good example of green chemistry-

Biopesticides offer powerful tools to create a new generation of sustainable agriculture products. They are the most likely source for alternatives to some of the most problematic chemical pesticides currently in use. Biopesticides also offer solutions to concerns such as pest resistance to traditional chemical pesticides, public concern about side effects of pesticides on the surrounding environment and ultimately, on human health.

Examples of Investigatory Projects in Green Chemistry-

Effects of Detergent Phosphates on Plant Growth

Because phosphates from household detergents seep into groundwater, a simulated effect can be investigated using a young pea plant and a solution of 90-percent water to 10-percent laundry detergent solution. Use two containers of pond water to simulate phosphate’s catalytic effect on algae growth by adding detergent solution to one container intermittently and using an unaltered container as a control. Record all observations qualitatively and quantitatively.

Effect of Pollution on Biodiversity

Use several terrariums made from local organisms, soils and water to investigate how pollution affects the amount of biodiversity in an ecosystem. Pollute terrariums by spraying diluted sulphuric acid into a terrarium to represent acid rain. Pollute another terrarium by carefully burning a birthday candle inside daily to represent smog. Leave one terrarium unpolluted to use as a control group. Record all observations qualitatively and quantitatively.

Storm Water Geologically Filtered

After a hard rain, water rushes into local waterways carrying many pollutants. Polluted water can be created by mixing water with small objects and dark colored dirt to represent different types of pollution. Devise a system of filtration using different sized grains of soil to create situations of altered porosities and permeability. Record all effects on pollution filtration qualitatively and quantitatively.

Future products-

PVC free cables -will reduce the use of both PVC and of lead, which is used as a stabilizer in PVC cabling. The Toxic Use Reduction Institute has been working on this new solder.

New lead-free solders with lower heat requirements are being developed.

Our new product development will focus on:

• Polymeric solutions, big molecules

• Reactive products that become bound to the final polymer

• Non-toxic small molecules

• Mineral products

• Minimizing the life cycle of products that remain in the environment 

• Improving recyclability

• Implementing measures throughout the supply chain to minimize emissions of persistent compounds

• Engaging distributors, customers and competitors in programs, such as VECAP, to eliminate all harmful products from the environment

• Continuing to advise consumers of the important of sustainable products.

Some basic ways in which we go about green product development –

Selection of reagents with lowest toxicity

Choice of catalysts that would provide highest reaction yield, thus minimizing waste

Choosing the right form of energy to maximize reaction efficiency

Precise calculations to predict with just two to three experiments how the reaction can be optimized, as well as the two or three preferable solvents for that reaction

Identification of potential hazards before conducting the reaction. Specific parameters such as heat of the reaction are studied.

Values of Green Chemistry in Innovation, Application and Technology: Indian Scenario-

Green chemistry focuses on the reduction, recycling, and/or elimination of the use of toxic and hazardous chemicals in production processes by finding creative, alternative routes for making the desired products that minimize the impact on the environment. Green chemistry is a more eco-friendly green alternative to conventional chemistry practices. The green chemistry movement is part of a larger movement ultimately leading to a green economy- namely sustainable development, sustainable business and sustainable living practices. Green chemistry can contribute to achieving sustainability in three key areas. First, renewable energy technologies will be the central pillar of a sustainable high-technology civilization. Second, the reagents used by the chemical industry. Third, polluting technologies must be replaced by benign alternatives. The aim of the article is to acquaint the academicians, researchers, scientists and engineers with values and positive impact of green Chemistry in innovation, application and Technology.

The green chemistry wave has reached our country too. We need to work for its betterment by encouraging the practices of green chemistry. Collaborations between industrial and academic partners are important to expedite the transfer of significant green products to the marketplace. For such collaborations to be successful, individuals in these two differently motivated cultures need to work together to advance green science. Governments could undoubtedly facilitate formation of more effective industrial/academic partnerships. Under an agreement with the Green Chemical Institute, University of Delhi has been accepted as an international chapter. The Indian chapter will promote green chemistry through education, information collection and dissemination, research and international collaboration via conferences, workshops, meeting and symposia. 

In India, although there is growing awareness about the ill effects of pollution, promotion of continual introduction of environmentally friendly products a methodologies in the chemical industry needs to be furthered. Usage of nonconventional technologies is highly popular in India. First in this list is the usage of microwaves. Further, the microwave chemists are turning their attention toward microwave-assisted dry-media reactions in order to minimize solvent usage, an added advantage to already established microwave chemistry. In addition to microwave-assisted reactions, ultrasonic and photochemical reactions are also used as nonconventional reaction technology. Analytical chemistry has been at the center of the green chemistry movement. Advances in analytical chemistry are key to environmental protection. In India, the focus for analytical chemistry is mainly on extraction technologies such as solid phase, ultrasound and microwave, supercritical fluid extraction, and automated soxhlet extraction. Monitoring and analysis of heavy metals and pesticides is very important for an agro economy-based country like India and chief governmental institutes like the Indian Agricultural Research Institute (IARI) and the Defense Research and Development Organization (DRDO) are working extensively in this field. Further removing of these elements from industrial and agrochemical usage is of prime importance for these.

Some recent developments and examples in green chemistry-

Chemists from all over the world are using their creative and innovative skills to develop new processes, synthetic methods, analytical tools, reaction conditions, catalysts, etc. under the new green chemistry cover. Some of these are.

A continuous process and apparatus converts waste biomass into industrial chemicals, fuels and animal feed. Another process converts waste biomass such as municipal solid waste, sewage sludge, plastic, tires and agricultural residues to useful products, including hydrogen, ethanol and acetic acid.

A method for mass producing taxol by semi continuous culture of Taxus genus plant.

A fermentation method for the production of carboxylic acids.

A method of partially oxidizing alcohol such as methanol to ethers, aldehydes, esters or acids, by using a supercritical fluid mobile.

A process for producing a fluoropolymer by using supercritical carbon dioxide.

A cost-effective method of producing ethyl lactate, a non-toxic solvent derived from corn.

A range of ‘organic solvents’ that are worker friendly and environmentally sound.

A new environmentally friendly technology in mixed metals recovery from spent acid wastes has been used to recover zinc and ferrous chloride from pickle liquor.

The demand for non-ionic surfactants is growing and a new example of this is alkyl glycoside, which is made from saccharide. This product can be used as a replacement for alkyl aryl sulphonate anionic surfactants in shampoos. Sodium silicate can be used as a more environmentally benign replacement for phosphorus-containing additives in washing powder. Three coconut oil soap bases for liquid cleansing applications have been developed. One of these products has very light color and low odor, making it suitable for introducing dyes and fragrances.

Feedstock recycling of plastic wastes into valuable chemicals useful as fuels or raw materials.

Developing Countries and Green Chemistry-

In developing countries, the introduction of green chemistry is still in a stage of infancy, despite the significant need and the significant role green chemistry can play. Many of the practices in developing countries are still far from the concepts of safety, pollution prevention and design of energy efficiency. Environmental pollution and waste generation are some of the aching problems many developing countries are suffering from. Many of the reasons behind these problems lie in policies and strategies adopted that are based on end-of pipe treatment, rather than pollution prevention at source or implementing life cycle thinking in handling waste problems. Most frequently, income generation activities are dependent on an efficient use of energy and other resources such as water, which may pose some serious problems to future generations.

The United Nations reporting on the millennium development goals at a country level indicated a high level of energy consumption and limited energy resources in most of the developing countries. The report strongly recommends the imperative need to ration the use of energy resources in these countries and to implement energy conservation policies. The same trend of difficulties developing countries face has been illustrated in the series of country reports produced by the rural development at the water and environment department of the World Bank.

Sustainable chemistry could play a pivotal role in salvaging many of the ailing conditions that many of the developing countries are subjected to. The use of solar energy, introduction of sustainable farming, recycling, and the implementation of life cycle thinking and life cycle analysis as a management tool for some of the chronic issues such as municipal waste management, are some few examples of how green chemistry can benefit developing communities.

Green chemistry can also have a very strong impact on water sufficiency issues in that part of the developing world where water resources is the most vital issue. It is through the implementation of cleaner production and use of safe and biodegradable chemicals that a huge volume of wastewater could be reused to quench the emerging, critical need of water in many of these countries.

Government Initiatives-

Government can do a lot of good for the cause of green chemistry by increasing public awareness and by bringing and enforcing strict environmental legislations. One of the recent and controversial examples of government initiative is the conversion of diesel vehicles to compressed natural gas (CNG) in order to reduce pollution. Relocation of industries into industrial areas away from residential parks is another bold step taken by the Delhi government. Further, the government is also concentrating on new projects such as fuel pellets from municipal waste, aspirated H-cylinder engines for light commercial vehicles (LCVs), meeting India 2000 emission norms, battery-powered cars for pollution-free driving, hydrogen energy and energy towers for new environment-friendly fuel, development of traditional herbal drugs as adapt gens a immunomodulators. The government should also increase funding to encourage research in green chemistry. By introducing green chemistry education at all levels, the government can build a solid foundation toward green chemistry in India.