Article on : - ADVANCING ENVIRONMENTAL SUSTAINABILITY:- IMPLEMENTING GREEN CHEMISTRY PRINCIPLES FOR POLLUTION CONTROL

                   ADVANCING ENVIRONMENTAL SUSTAINABILITY:- IMPLEMENTING

                       GREEN CHEMISTRY PRINCIPLES FOR POLLUTION CONTROL

                                                                     Diya N C

                      St. Joseph College of Teacher Education For Women , Ernakulam

 Abstract

Green chemistry, an emerging field, puts into practice 12 principles to attain a pollutant-free environment in air, water, and soil. Green chemistry, also referred to as sustainable chemistry, encompasses the entire life cycle of a chemical product, incorporating its design, manufacturing, usage, and eventual disposal. It involves the creation, design, and implementation of chemical products and processes with the aim of minimizing or eliminating the utilization and creation of hazardous substances. When applied across industries, governmental policies, daily practices, and global education systems, these principles contribute significantly to environmental, economic, and social benefits. This overview sheds light on the systematic application of these principles and identifies barriers . The article explores a three-point PAS strategy (pollution and accidents prevention, safety and security assurance, and energy and resource sustainability) to surmount these barriers. It delves into the detailed discussion of the role of innovative technology in addressing air, water and soil pollution. Additionally, the article presents valuable success stories showcasing the positive impact of green chemistry principles in controlling pollution and highlights their role in achieving overall environmental sustainability.

Keywords :- Green Chemistry , Principles , Pollution Control , Environmental Sustainability

Introduction :-

 Green chemistry involves the intentional design of chemical products and processes with a primary objective: the reduction or elimination of hazardous substances. This commitment extends comprehensively across the entire life cycle of a chemical product, encompassing its conception, manufacturing, utilization, and eventual disposal. By focusing on sustainability from the initial design stages through to the end-of-life considerations, green chemistry strives to minimize environmental impact and promote a safer, more ecologically conscious approach to chemical development and utilization. 

Green chemistry distinguishes itself by proactively reducing pollution at its origin, specifically by minimizing or eliminating the hazards associated with chemical feedstocks, reagents, solvents, and end products. Unlike pollution clean up, commonly known as remediation, where waste streams are treated or environmental spills are addressed, green chemistry operates on a preventative principle. It focuses on averting the generation of hazardous materials from the outset. Remediation activities, often involving the separation and treatment of hazardous chemicals, typically do not align with green chemistry principles. The essence of green chemistry lies in sidestepping the creation of harmful substances, contrasting with the remediation's reactive approach.

Green Chemistry is a recent field focusing on molecular-level solutions for sustainability. It aims to design chemical products and processes to reduce pollution at its source and minimize risks to human health and the environment. The concept originated in the 1960s with Rachel Carson's book "Silent Spring," highlighting the detrimental effects of certain chemicals on ecosystems. 

The Environmental Protection Agency (EPA) initiated its regulatory role by banning DDT and other pesticides. In the 1980s, a global dialogue, including the OECD, focused on pollution prevention, leading to international recommendations. In 1988, the EPA established the Office of Pollution Prevention and Toxic Substances, officially introducing Green Chemistry (GC). GC challenges chemists to create products and processes without toxins, aligning with the Pollution Prevention Act of 1990. Long-term environmental issues like acid rain and global warming necessitate the development of eco-friendly processes and products through GC, involving diverse stakeholders globally. Industry leaders play a crucial role in translating research into practical solutions.

Furthermore, technologies that qualify as green chemistry extend beyond merely avoiding hazardous materials in product design; they encompass innovations that improve environmental clean up itself. For instance, replacing a hazardous sorbent used to capture mercury with a non hazardous alternative not only enhances the efficacy of remediation but also adheres to the fundamental green chemistry tenet by eliminating the production of the hazardous sorbent altogether. This holistic approach underscores green chemistry's commitment to sustainable practices and pollution prevention .

Theme :-

Green chemistry :- 

Green chemistry is the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances. Green chemistry applies across the life cycle of a chemical product, including its design, manufacture, use , and ultimate disposal.

Green Chemistry involves designing and applying chemical products and processes to reduce or eliminate hazardous substances across the entire life cycle, including design, manufacturing, usage, and disposal. Also known as sustainable chemistry, it operates at the molecular level, applying innovative solutions to diverse environmental challenges in all chemistry domains. This approach achieves source reduction by preventing pollution generation, lessening and eliminating hazards from existing processes, and designing products with reduced intrinsic hazards. Unlike remediation, which treats waste streams, Green Chemistry prevents hazardous materials from entering the environment, showcasing its proactive nature. 

For instance, in green chemistry technology, replacing a hazardous sorbent used for capturing mercury with a non-hazardous alternative ensures the hazardous sorbent is never manufactured, aligning with the essence of green chemistry.

Twelve Principles of Green Chemistry :-

Green Chemistry has emerged as an important aspect of all chemistry Green Chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. Green Chemistry is based on Twelve Principle.

Principles of Green Chemistry:-

 1: Waste Prevention :-

It is better to prevent waste than to treat or clean up waste after it has been created. Thus, chemical processes should be optimised to produce the minimum amount of waste possible.

 A metric, known as the environmental factor (E factor), was developed to gauge the amount of waste a process created, and is calculated by simply dividing the mass of waste the production process produces by the mass of product obtained. Lower value of E factor indicates better results. Other methods of assessing amounts of waste, such as comparing the mass of the raw materials to that of the product, are also used.

2: Atom Economy:-

 Atom economy is a measure of the amount of atoms from the starting material that are present in the useful products at the end of a chemical process. Thus, synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product. Side products from reactions that aren’t useful can lead to a lower atom economy, and more waste. In many ways, atom economy is a better measure of reaction efficiency than the yield of the reaction; the yield compares the amount of useful product obtained compared to the amount you’d theoretically expect from calculations. Therefore, processes that maximise atom economy are preferred.

 3: Less Hazardous Chemical Synthesis :-

Synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment.

4: Designing Safer Chemicals :-

Chemical products should be designed to effect their desired function while minimizing their toxicity. The design of safer chemical targets requires a knowledge of how chemicals act in our bodies and in the environment. In some cases, a degree of toxicity to animals or humans may be unavoidable, but alternatives should be sought.

 5: Safer Solvents & Auxiliaries :-

Many chemical reactions require the use of solvents or other agents in order to facilitate the reaction. They can also have a number of hazards associated with them, such as flammability and volatility. Solvents might be unavoidable in most processes, but they should be chosen to reduce the energy needed for the reaction, should have minimal toxicity, and should be recycled if possible. 

6: Design for Energy Efficiency :-

Energy-intensive processes are unacceptable in green chemistry. Energy requirements of chemical processes should be recognized for their environmental and economic impacts and should be minimized. If possible, synthetic methods should be conducted at ambient temperature and pressure.

7:Use of Renewable Feedstocks:-

A raw material or feedstock should be renewable (e.g., chemicals derived from biological sources) rather than depleting whenever technically and economically practicable. For example petrochemicals are non-renewable resources which are employed as starting materials in a range of chemical processes can be depleted.

 8: Reduce Derivatives:-

 Unnecessary derivatization (use of blocking groups, protection/deprotection, temporary modification of physical/chemical processes) should be minimized or avoided if possible, because such steps require additional reagents and can generate waste. Alternative methods must be developed which do not require the such groups for example enzymes which are highly specific. 

9: Catalysis :-

The use of catalysts can enable reactions with higher atom economies. Catalysts themselves aren’t used up by chemical processes, and as such can be recycled many times over, and don’t contribute to waste. They can allow for the utilisation of reactions which would not proceed under normal conditions, but which also produce less waste. 

10: Design for Degradation :-

Organic pollutants do not decompose and can accumulate in the environment for example halogenated compounds (DDT). Where possible, these chemicals should be replaced with chemicals that are more easily decomposed by water, UV light, or micro-organisms. Chemical products should be designed so that at the end of their function they decompose into harmless degradation products and don’t have adverse impacts on the environment. 

11: Real Time Pollution Prevention :-

Monitoring a chemical reaction as it is occurring can help prevent release of hazardous and polluting substances due to accidents or unexpected reactions. With real time monitoring, warning signs can be spotted, and the reaction can be stopped or managed before such an event occurs.

 12: Safer Chemistry for Accident Prevention :-

Working with chemicals always carries a degree of risk. However, if hazards are managed well, the risk can be minimised. This principle clearly links with a number of the other principles that discuss hazardous products or reagents. Where possible, exposure to hazards should be eliminated from processes, and should be designed to minimise the risks where elimination is not possible.

Barriers and Challenges:-

Regulatory Barriers and Challenges: 

Navigating complex and sometimes rigid regulations poses a significant hurdle for green chemistry adoption. Existing regulatory frameworks may not always align with or incentivize sustainable practices, making it challenging for businesses to implement green alternatives without facing obstacles.

 Institutional Barriers and Challenges: 

Resistance to change within established institutions can impede the integration of green chemistry. Lack of awareness, outdated policies, and organizational inertia may hinder the transition toward more sustainable practices. 

Technological Barriers and Challenges:

 Developing and implementing new green technologies can present technical challenges. This includes the need for research and innovation to create effective alternatives to hazardous chemicals or processes, as well as ensuring scalability and efficiency in real-world applications.

 Financial Barriers and Challenges: 

The initial costs associated with research, development, and implementation of green chemistry practices can be a significant barrier. Businesses may be hesitant to invest in these initiatives if they perceive higher upfront costs without immediate economic benefits.

 Addressing these challenges requires collaborative efforts from regulatory bodies, institutions, researchers, and financial stakeholders to create an environment that supports and incentivizes the adoption of green chemistry principles

Sustainability:-

Sustainability hinges on a fundamental principle: the entirety of our necessities for survival and overall well-being is intricately linked, whether in a direct or indirect manner, to the health and stability of our natural environment.

Principles of Sustainability :-

There are three principles which define sustainability in any type of material, as described by the American ecologist and economist Herman Daly: 

Non renewable resources should not be depleted at rates higher than the development rate of renewable substitutes.

 Renewable resources should not be exploited at a rate higher than their regeneration levels .

The absorption and regeneration capacity of the natural environment should not be exceeded.

Design principles for sustainable and green chemistry:-

Maximize Resource Efficiency Minimizing waste in a chemical reaction of process may include strategies to reduce energy use, increase the mass of raw materials incorporated into a final product (atom economy), recover and reuse of solvents and reagents, and reduction of process time. 

 Eliminate & Minimize Hazards & Pollution Safer chemistry can be achieved through smarter design. It is critical that chemists work to understand toxicity and remove hazardous chemicals from reactions when possible. Other approaches include real-time analysis of processes and monitoring and minimizing laboratory waste. 

 Design Systems Holistically & Using Life Cycle Thinking Sustainable design demands looking at chemistry and engineering from a systems perspective and considering the overall impact of processes and products. Considering the end-of-life of a product in the design phase will help efforts to recycle, reuse, compost or otherwise dispose properly of products. Use of renewable materials and the ability to separate materials at end of life are key considerations. 

PAS Strategy:-

The PAS strategy, encompassing pollution and accidents prevention, safety and security assurance, and energy and resource sustainability, offers a holistic framework for addressing environmental challenges and promoting sustainable practices.

This strategy aims to integrate the prevention of pollution and accidents, the assurance of safety and security, and the sustainability of energy and resources. By combining these elements, the PAS strategy provides a comprehensive approach to implementing Green Chemistry principles and fostering environmental sustainability across various domains. 

Technology:-

Atmospheric CO2 Capturing and Conversion Technology:-

 Through two decades of dedicated efforts, green chemists have contributed invaluable technologies, with a prime example being the integrated carbon capture, utilization, and storage (CCUS) approach, addressing the urgent concern of atmospheric CO2 accumulation. This comprehensive technology involves sequestration, transportation, and conversion or storage of captured CO2, utilizing methods ranging from physical and chemical absorption with substrates like activated carbon to innovative solutions such as green polymeric membranes, ceramics, metal–organic frameworks (MOF), covalent-organic frameworks (COF), cryogenic chambers, and enzyme technologies, all of which not only play a pivotal role in environmental conservation but are also indispensable for shaping a sustainable and resilient economic framework.

Water Splitting Technology for the Production of Renewable Hydrogen Fuel :-

In response to the escalating global energy crisis, hydrogen (H2) has emerged as a highly sustainable, environmentally friendly, and clean energy alternative in the twenty-first century, poised to replace depleting fossil fuel sources; electrochemical water splitting, despite its longstanding recognition for H2 production, faces efficiency challenges due to high costs, electrode instability, and limited scalability, prompting chemists worldwide to ardently pursue the development of economically viable and efficient technologies for this purpose, with a focus on utilizing green renewable energy sources to power electrolytic oxidation and reduction reactions, resulting in the creation of diverse green energy systems such as two-electrode electrolysis, solar cell-driven water splitting, photoelectrode devices, thermoelectric devices, triboelectric nanogenerators, as well as other advanced devices like pyroelectric and water–gas shift reaction setups, collectively representing a monumental stride in achieving large-scale H2 fuel production through water splitting driven by sustainable green energy systems.

Use of Greener Catalysts for Sustainable Synthetic Technology :-

 In chemical industry, catalysis plays a pivotal role, expediting reactions, enhancing selectivity, and reducing energy requirements; traditional catalysts often involve expensive and toxic noble metals. Green catalysts, essential for sustainability, require characteristics like high selectivity, activity, stability, easy separability, and reusability, ideally crafted from environmentally benign materials such as organic compounds and abundant metals. Enzyme catalysts and visible light photocatalysts are gaining prominence, while magnet-supported catalysts offer easy separability and reusability. The pursuit of green catalysts is crucial for achieving economic benefits and environmental protection, a fundamental step toward sustainability in the chemical industry.

Green and Sustainable Solvent :-

The substantial use of volatile, flammable, and toxic organic solvents in chemical, pharmaceutical, and research industries contributes to significant environmental pollution, with approximately 20 million tons released annually into the atmosphere as solvent waste. To address this issue, the chemical community emphasizes the adoption of greener solvents, such as water, ionic liquids, task-specific ionic liquids, supercritical fluids, and non-toxic liquid polymers, in various chemical processes. These green solvents must meet specific criteria, including low toxicity, ease of availability and recycling, and high process efficiency. By incorporating green solvents, chemical reactions can be optimized, reducing processing steps minimizing solvent usage, and opening new avenues and technologies that align with the principles of sustainability.

Dow Agrosciences LLC :-

Dow AgroSciences addresses soil pollution by creating Instinct, a nitrification inhibitor improving nitrogen availability for plants. This innovation led to a 664,000-ton reduction in CO2 emissions and a 50 million bushels increase in corn production, earning them the 2016 EPA Presidential Green Chemistry Challenge Award for cleaner manufacturing.

Conclusion:-

Review delves into the fundamental concept of Green Chemistry (GC) and its 12 principles, emphasizing their application in developing pollution-free products. Barriers to implementing these principles are explored, alongside the role of PAS strategies (Prevention, Assurance, and Sustainability) in overcoming these challenges. Notably, the discussion underscores the pivotal role of technology in establishing Green Chemistry. While the strategy presented in this chapter is straightforward, it has sparked considerable interest among researchers, prompting further exploration and development in this crucial field.

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