Perspective Chapter: Implementing Green Chemistry Principles for Pollution Control to Achieve Environmental Sustainability – A Review

Abstract

Green chemistry is an emerging field in which 12 principles of green chemistry are put into practice to achieve a pollutant-free environment (air, water and soil). Simultaneously, when implemented in industrial practice, government policy, the practice of daily life, and the education system around the world, these 12 principles can play an important role in environmental, economic, and social benefits. This overview sheds light on the principle and its applicability based on systematic surveys. Additionally, this review identifies related barriers to GC implementation, such as: regulatory, institutional, financial, technological and public barriers to achieve the goal of a pollution free product. A three-point strategy (so-called PAS strategy, i.e. pollution and accidents prevention, safety and security assurance, and energy and resource sustainability) was explored to overcome barriers. In addition, the role of innovation technology and integration management in overcoming air, water and soil pollution system was discussed in detail. Finally, some of the valuable success stories based on GC implementation in controlling air, water and soil pollution were presented. This report highlights the success of implementing 12 GC principles in achieving overall environmental sustainability.

1. Introduction

Green chemistry (GC) is a relatively new, emerging field that seeks to work at the molecular level to achieve sustainability through the design of chemical products and processes with the goal of (a) reducing the generation of pollution to minimize source and (b) risk to human health and the environment [1]. This definition and the concept of GC first came into focus in the 1962s in Rachel Carson’s scholarly book Silent Spring, in which he described the devastating effects of certain chemicals on local ecosystems [2]. To protect the quality of the environment, the US Congress promptly passed the National Environmental Policy Act (NEPA) in 1969 [3]. With health and the environment now a priority, President Richard Nixon founded the United States in the 1970s [4]. The Environmental Protection Agency (EPA), a federal regulator whose very first major decision was to ban the use of DDT and other chemical pesticides [5]. In the 1980s, the chemical industry and EPA’s primary focus was pollution cleanup, and industry and government leaders began an international dialog, with groups such as the Organization for Economic Co-operation and Development (OECD) raising problems and seeking preventive solutions. They made a series of international recommendations focused on cooperatively modifying existing chemical processes and preventing pollution. Additionally, in 1988, the office of pollution prevention and toxic substances was formed within the EPA to promote these environmental goals, and the term GC was first officially announced [6]. Therefore, GC goes one step further and creates a new reality for chemistry and engineering by challenging chemists and engineers to develop chemicals, chemical processes and commercial products without producing toxins and waste products. Meanwhile, the Pollution Prevention Act of 1990 marked a regulatory shift from pollution control to pollution prevention as the most effective strategy for these environmental problems [7]. By the mid-twentieth century, however, some of the long-term adverse effects of these advances could not be ignored, such as acid rain, global warming, declining forest health, and depletion of the Earth’s ozone layer [1]. Some common chemicals are suspected of causing or being directly related to human cancer or other harmful effects on human health and the environment [7].

In order to overcome such problems, it is necessary to develop chemical processes and environmentally friendly products that prevent environmental pollution in the first place [8]. Through the practice of green chemistry, alternatives to hazardous substances can be created through the use of raw materials [9]. Chemical processes can be developed that reduce waste and reduce the need for increasingly scarce resources [8]. The worldwide implementation of GC requires the efforts of many governments, policy makers, academia, scientific societies, industry, trade organizations, small businesses, non-governmental organizations, research centers and other government agencies [1]. Today’s industry leaders can do the job it takes chemists and engineers to move research and innovation from the lab to the boardroom by developing viable industrial products [10].

In recent years, international efforts in green chemistry have significantly boosted hopes of addressing environmental, health, and economic challenges. The International Union of Pure and Applied Chemistry (IUPAC) works with industry and other research organizations around the world to help solve this pollution and other environmental problems. Many successful entrepreneurial companies whose products are based on the application of green chemistry and technology have emerged as part of the pollution prevention program. When thinking about the development of GC, we must always remember the work co-authored by Paul Anastas and John C. Warner, who derived 12 principles (Figure 1) of GC that embodies a philosophy that led academic and industrial scientists to do so motivated to achieve the goal of environmental sustainability [11]. Figure 1 shows the 12 principles that act as a clock and illustrate the importance of time, energy and the environment. The major goals of this chapter are to (1) to determine theory of GC to put in to real life practice, (2) to identify associated barriers for the deployment of GC for pollution control.

Figure 1.

The 12 principles of green chemistry to implement in pollution control.

This review focuses on the detailed discussion of 12 principles and the barriers to their implementation. Furthermore, controlling air, water and soil pollution is the focus of this review, so this review sheds light on their implementation by providing strategies. Nevertheless, this chapter presents the role of their innovative technology in controlling each individual pollution. Nevertheless, integration management was discussed to determine the role of management in implementing the strategy. Finally, a case study on air, water and soil pollution using the green chemistry approach was discussed.

2. Twelve (12) points of green chemistry

2.1 Waste prevention

Principle: It is better to avoid waste than to treat or dispose of it after it is created. There are three sources of waste generation, for example during production, during distribution of the product and during consumption of the product [12].

Application: Waste generation in manufacturing comes primarily from sources such as incomplete reaction conversion, and waste from chemicals used in the process but not consumed in the reaction, such as solvents and suspending agents, residues, catalysts, etc. These wastes can take many forms and impacts in terms of nature, toxicity, quantity and mode of release into the environment, depending on the state. In order to control the effects, the E-factor (mass of waste/mass of products), the environmental impact factor, was introduced in 1992 [12]. It is a measure that can be used to calculate the amount of waste generated per kilogram of product and measure the environmental impact of a manufacturing process. By providing such a factor, creative solutions to avoid inefficient industrial production have been achieved. For ethylene oxide production, an E-factor of 5 and 0.3, respectively, was observed for the chlorohydrin process and the catalytic oxidation process [13]. This means that for every kilogram of product, 5 kg of waste was generated by the chlorination process and reduced 16-fold and 0.3 kg was generated after the catalytic oxidation process.

2.2 Atom economy

Principle: Atomic economics is a major development that goes beyond the traditional concept of percent yield [13]. This is because the yield is calculated by considering only one reactant and one product.

Application: The central principle of GC is to design processes in such a way that the greatest possible amount of all raw materials ends up in the product and a minimum of waste is produced. Most reactions can have a high percentage yield, but also produce a lot of waste products. This type of reaction has a low atom economy. When designing an environmentally friendly chemical process, both yield and atom economy must be considered. Ethylene oxide is an important raw material for the production of epoxy-functional materials, ethoxylates (surfactants), ethylene glycol ethers (solvents), etc., which are produced by the chlorohydrin process (two-step process, see Figure 2A). Meanwhile, in 1937, Union Carbide introduced a catalytic oxidation process (one-step process) to produce ethylene oxide (see Figure 2B) using silver metal as a catalyst. Table 1 shows the atom economy calculations of both processes. As a result, it was found that the atom economy of the chlorohydrin process and the catalytic oxidation processes were 23 and 100%, respectively [13]. Silver is the most active and selective catalyst for the reaction. Today, all ethylene oxide worldwide is produced exclusively via the catalytic route.

Figure 2.

Synthesis of ethylene oxide by (A) chlorohydrin process, and (B) catalytic oxidation process.

Process	Reactant		Product				Atom economy
			Utilized		Non utilized
	Formula	Formula weight (g/mol)	Formula	Formula weight (g/mol)	Formula	Formula weight (g/mol)
(A) Chlorohydrin process (E-factor = 5)	C2H4	28	C2H4	28
	Cl2	71		0	Cl2	71
	H2O	18	O	16	H2	2
	Ca(OH)2	74		0	Ca(OH)2	74
	CH4H8O3CaCl2	191	C2H4O	44	H4O2CaCl2	147	44/191 = 23%
(B) Catalytic oxidation process (E-factor = 0.3)	C2H4	28	C2H4	28		0
	½ O2	16	O	16		0
	C2H4O	44	C2H4O	44			44/44 = 100%

Table 1.

E-factor and atom economy of ethylene oxide produced by (A) chlorohydrin process, and (B) catalytic oxidation process.

2.3 Less hazardous chemical syntheses

Principle: Synthetic methods should be designed in such a way that the formation of substances (product or by-product) has little or no toxicity to human health and the environment.

Application: Chemical products should be designed to prevent the effect while reducing toxicity. In practice, many researchers worked to reduce solvent consumption and produce more efficient processes with higher yields and less hazardous waste/intermediate materials [14]. Building on this, the 2005 Nobel Prize in Chemistry was awarded for advances in green chemistry. To illustrate this concept, a Witting reaction invented by Georg Wittig in 1954, in which he incorporated an alkane into a molecule, was highlighted [15]. A triphenylphosphonium halide was added to a solution of n-butyllithium in diethyl ether. After ylide formation, the carbonyl compound was added and refluxed overnight. After some time, a milder base was used in place of the lithium compound to form the ylide, and N, N-dimethylformamide was used in place of diethyl ether. The Witting reaction was modified with aqueous sodium hydroxide at room temperature to aid GC in solvent-free synthesis. Here, an aromatic (any) aldehyde is added to a ylide formation by reacting benzyl-triphenylphosphonium chloride with sodium hydroxide by simply stirring at room temperature for 30 min (see Figure 3) [14]. The advantage of such a reaction was the replacement of the reaction solvent with water.

Figure 3.

Green route scheme for the wetting reaction of substituted benzaldehyde.

2.4 Safer chemicals

Principle: Chemical products should be designed to perform their desired function and effectiveness without compromising on a minimal level of toxicity.

Application: To date, most industrial processes have been developed and aligned with the end goal of producing a product and its utility, regardless of the impact on natural resources, the waste generated by the invention, and its toxicity [11]. To understand this concept, it is essential to understand the flame retardants used in the plastics industry. In general, organ halogen and organophosphorus compounds are widely used as flame retardants. In the organ halogenated compound, brominated aromatics in particular have been the most commonly used because of their low cost and efficiency. However, it exhibits less bio-accumulative properties in the environment and the associated health risks are significantly higher. More recently, bio-based flame retardants are derived from tartaric acid, a by-product of winemaking used in the polymer composites industry [16].

2.5 Safer solvents and auxiliaries

Principle: Solvents are the king of all types of reactions (mainly) to get a good conversion rate. The use of auxiliary materials (e.g. solvents, separating agents, etc.) should be superfluous as far as possible and harmless in use.

Application: In many cases reactions would not take place without solvents and/or material release agents. However, solvents are responsible for about 75% of the total environmental impact of a traditional chemical operation [17]. In addition, they lengthen the process steps by being heated, distilled, cooled, pumped, blended, distilled under vacuum and filtered, and for the most part are not recycled. To avoid such effects, in some cases microwave-assisted solid-phase reactions, green solvents, and water media were alternative ways to reduce solvent consumption [18]. Among other things, the microwave-assisted reaction is very fast, has a shorter reaction time, a higher degree of purity and a higher yield after the reaction [18]. Most importantly, no additional steps are required to obtain a pure product.

2.6 Energy efficiency

Principle: requirement of chemical processes should be recognized and minimized with regard to its ecological and economic effects.

Application: In the general case of solvent removal, chemistry laboratories need a rotary evaporator, which requires the combined use of a heat source, a vacuum pump, a rotary motor, and a condenser. Meanwhile, the energy input and associated costs are modest compared to a larger industrial scale for solvent removal. To control the energy consumption, you need to design the reaction under the ambient conditions of room temperature and atmospheric pressure [11]. In 2012, Cytec Industries Inc. received the Presidential Green Chemistry Challenge Award for innovation in energy-saving reaction conditions. In short, alumina is a raw material for aluminum, which is produced from bauxite using the Bayer process. Minerals were deposited on heat exchangers and pipes that were cleaned with sulfuric acid when the engine was shut down. To avoid this problem, Cytec developed its MAX HT Bayer Sodalite Scale Inhibitor, which contains an active polymer with silane functional groups for the Bayer process. This polymer deposited on surfaces, increased evaporation and reduced caustic soda losses, thereby reducing the use of vapor emissions from the combustion of carbon-based fuels. This process also reduces the use of sulfuric acid to clean heaters. After implementing this process at all steel mills, it was determined that the energy savings equated to approximately 7 billion pounds of CO₂ not released into the atmosphere. In addition, the use of sunlight to promote chemical reactions and the conversion of solar fuels from CO₂ offer significant potential for sustainable energy solutions [19].

2.7 Renewable feedstocks

Principle: A raw or starting material should be renewable and non-exhaustive whenever technically and economically feasible.

Application: Recently, most of our manufacturing products are derived from petroleum feedstocks or natural gas. Renewable raw materials are often made from agricultural products or come from living organisms [20]. Many products from biological sources are widely used, e.g. Algae is used in the cosmetics industry, lignin is an important waste material from the pulp and paper industry for energy production, additives are converted into DMSO as well as humic acid, starch and oil for the production of detergents, bioplastics are Synthesis for packaging, cars, etc. [21]. Among biopolymers, polylactic acid is the most commonly used biopolymer in the packaging and healthcare sectors today [22]. Fermenting starch derived from glucose in the presence of CO₂ and yeast produces succinic acid, which is used in the synthesis of a variety of chemical products such as detergents and biodegradable plastics. In recent years, CO₂ has been used as a feedstock for mineralization in the cement industry through the carbonization process to the High-Gravity process. Similarly, bio-butanol is also produced from renewable feedstock and can be used for many energy applications [23]. Composed of triglycerides, vegetable oils are widely used in foods, pharmaceuticals, cosmetics, fuels, paints and building materials. Research into the use of renewable materials is advancing rapidly and one cannot hope to provide an exclusive overview of all possibilities.

2.8 Reduce derivatives

Principle: Unnecessary derivatization should be minimized or avoided whenever possible, since steps require additional reagents and can generate waste.

Application: Synthesis is a multi-step process to produce chemical products using various solvents and reagents at elevated temperatures and/or pressure. This process requires additional purification and separation steps after each process and generates waste that gives the impression that the recovery is less than 100%. Noncovalent derivatization is an alternative to traditional synthesis, in which the properties of a starting material are modified by covalently attaching various functional groups to it without the use of solvents. Thus, no waste and no purification is required to obtain modified products. To understand this concept, it is necessary to understand the Polaroid instant imaging mechanism. Here, the solubility of hydroquinones at elevated pH by bis(N, N-dialkyl)terephthalamide modification was modified by a noncovalent derivatization method instead of the (traditional) method using base-labile covalent protecting groups [24]. It solved the problem without altering the original hydroquinone structures and minimized waste material and energy by performing the solvent-free milling, purification processes, and waste disposal associated with the traditional covalent derivatization process in one step.

2.9 Catalysis

Principle: Catalytic reagents are superior to stoichiometric reagents to increase product yield. As described in the first principle, waste avoidance can be achieved through a higher conversion rate, which can be achieved by a catalyst.

Application: One of the most important catalytic reactions of the last century is the acid-catalyzed Friedel-Craft alkylation and acylation reaction for the synthesis of alkylbenzenes, which are valuable intermediates in specialty chemistry. In this reaction, soluble Lewis acid AlCl3 or mineral HF acid was added as a catalyst and resulting in a large amount of hazardous substances (Figure 4a) [25]. To cope with this situation, solid acid catalysts have been developed from an economical and ecological point of view to achieve higher yields with fewer pollutants (Figure 4b). In this century there was the renewable catalyst or enzyme catalyst. Enzyme catalysts were used to convert the pollutant gas CO₂ into useful solar fuels (Figure 4c) [26]. In this way, harmful substances are converted into useful substances. Furthermore, since biocatalysis is a biomimetic approach based on natural or modified enzymes, it is also used for the conversion of biomolecules instead of petrochemicals.

Figure 4.

Catalytic reaction such as Friedel-crafts alkylation by (a) conventional route, and (b) green route; enzymatic reaction for solar fuel production (c).

2.10 Design for degradation

Principle: Chemical products should be designed so that at the end of their useful life they break down into harmless decomposition products and do not remain in the environment.

Application: There is a risk of confusion in understanding this concept, where biomaterials are not necessarily made from renewable resources, but refer to the ability of materials to break down into energy and more basic components such as carbon dioxide, methane and water. Biodegradation occurs aerobically and anaerobically, with organic matter being converted into basic elements in the presence or absence of oxygen. In the last 10 years, due to the global worm effect, the demand for sustainable and renewable raw materials for personal care products has increased. Prior to this type of concept, long-chain ammonium salts such as di(hydrogenated)tallow dimethyl ammonium chloride (DHTDMAC) (Figure 5) were used as personal care products. However, it has lower biodegradability and intrinsic eco-toxicity [27]. The new salt made from natural fatty acids has higher biodegradability compared to DHTDMAC (see Figure 5). Made from fatty acid, the surfactant has superior physicochemical properties, is easily synthesized and over 70% biodegradable, providing a good alternative to traditional petrochemical-based surfactants.

Figure 5.

Design of various biodegradable surfactants.

2.11 Real time analysis of pollution

Principle: Analytical methods need to be further developed to enable real-time monitoring and control during the process before hazardous substances are formed. In most chemical processes, temperature and pressure are linked.

Application: Temperature and pressure sensors were used to monitor the reaction conditions. However, they only measure the condition of the reactor, but the composition of the mixture, the conversion ratio of the mixture and the physical properties must be measured with analytical techniques (see Table 2) to avoid generating waste. The product/process is safer for human health and the environment. Through this type of practice, the goal of green analytical chemistry to measure chemicals without generating waste and minimizing or eliminating the formation of by-products can be achieved [11]. The advantage of the real-time analysis process is to quickly take action to avoid accidents, energy loss and by-products that would survive additional cleaning, separation or filtration steps. In particular, materials used in the manufacture of such an instrument, such as a mercury electrode replaced with a carbon electrode and a Li-ion battery replaced with a carbon electrode battery, are also considered. After implementing such small things for production, pollution and by-products can be eliminated and the product obtained can be called a clean product.

Type of Basic Instruments	Type of Industries
	Basic Inorganic	Drug	Dyes intermediate	Fertilizer	Refineries and petroleum/Polymer	Pesticide	Electroplating and heat treated	Oil and soap
Gas chromatography	Salts	Drug Molecule and purity	Composition of mixture	Reaction conversion and purity	Yield and Conversion rate	Conversion rate	Toxic chemicals and metals	Spent soap lye
Raman spectroscopy	Acid/Alkalis	Molecule	Structure of product	Molecular structure	Molecular structure and bonding	Molecular structure	Bonding of materials	Emulsion rate
Optical spectroscopy	NA	NA	NA	NA	Composition of a real mixture	NA	Coating of transparent material	Wettability and contact angle
UV/Vis spectroscopy	Inorganic pollutants	Solid pollutant	Water-soluble pollutants	Pollutants	Vinyl polymeric conversion	By-products	Bond formation rate	By-products
Infrared spectroscopy	Inorganic pollutants	By products	By products	By-products	Structural detail of product and waste	Structural detail of product and waste	Functional group of coating materials	Functional or coating groups

Table 2.

Type of analytical techniques utilized in different kinds of industries.

2.12 Accident prevention

Principle: Substances and the form of a substance used in a chemical process should be selected to minimize the risk of chemical accidents, including releases, explosions and fires.

Application: When it comes to prevention, not only chemical accidents count, but also protection against damage, risks, dangers, injuries and damage. In general, accident prevention is divided into four categories: personal protection, management and control of work processes, technical control and elimination of the accident before it occurs. According to the OECD principles of good laboratory practice, the generation of high-quality and reliable test data/products is related to personal and industrial safety. Personal safety through awareness, cleanliness, safer work culture and use of personal protective equipment such as gloves, goggles, lab coat/apron, shoes and masks. The Occupational Health and Safety Administration guidelines must be followed in controlling and managing work practices to prevent accidents. Meanwhile, according to Environmental Protection Agency guidelines, materials and processes must be selected to be safer for the environment. Under the Chemical Accident Prevention and Clean Air Act Amendments of 1990, accident prevention begins with identifying the hazards, such as: exclusive, toxic, flammable or global hazards. In this way, the production or laboratory work is the first to benefit from the risk reductions. There are several serious accidents related to the chemical industry or chemical materials, resulting in significant losses to people, animals and the environment, for example. The above incidents are memorable events for everyone, especially the scientific community, reminding us to use safer alternative chemicals to avoid accidents.

3. Goals and objectives

Government, policymakers, business, industry and the public now see sustainable development as a necessary goal to achieve the goals of the Paris Agreement of November 4, 2016 [28]. In the context of industrialization, the creation of cleaner products and cleaner processes plays a key role in reducing pollution minimize and to maintain and improve our atmosphere and thus our quality of life. This can be achieved through GC Development. In fact, these challenges are primarily associated with chemistry, chemical engineering and chemists. The reason the manufacturing process creates millions of tons of waste, and reducing or eliminating that waste is a critical issue facing the world today. Therefore, a challenge for chemists and their associations is to develop new products, processes and services that achieve the goal of a pollution-free environment. This can be achieved by reducing the material and energy intensity of chemical processes and products, minimizing or preventing the spread of harmful chemicals in the environment, maximizing the use of renewable resources, and extending the shelf life and recyclability of products. To achieve the goal of a pollutant-free atmosphere, the aim of the paper was to (1) identify the principle of GC and the role of GC in preventing pollution, (2) the obstacles and challenges in establishing GC in the system to identify, (3) The role played by innovative technologies in preventing air, water and soil pollution is determined. In addition, three case studies on different countries’ approaches to tackling GC-related challenges were reviewed and illustrated.

4. Barriers and challenges

Basically, when we talk about the barriers, it is necessary to consider a complex set of issues associated with the implementation of GC for pollution control. To justify that barriers are categories of institutional, regulatory, technological, financial and public (cultural) support to achieve comprehensive pollution control. There are significant interactions and overlaps between these categories themselves.

4.1 Regulatory barriers and challenges

In recent years, income growth has changed according to the country’s urbanization development, which has led to an increase in export and import. In addition, with the development of the transportation system, the world is becoming more and more connected, and the export and import of chemicals is increasing rapidly. Therefore, many chemical companies have established their business according to the relaxation of regulations in the country where they manufacture or sell their products. Many chemical companies use their resources for mandatory actions and harm the environment, air pollution and water instead of investing in research and development for new products and processes. In most cases, landfilling the waste is not the ultimate option, and the quality of the landfill is also questionable if it is not properly segregated. Such governmental habits and underestimations can be a barrier to new GC innovations. In addition to waste management, the government must also take care of corporate policy to avoid conflicts [29]. In some cases, the sale of one company or product interfered with the sale of another product, leading to conflict and implementation difficulties. At this point, government environmental and health policies must consider the benefits and make their choices rather than being economic or political [30]. In addition, the central government must provide adequate rights and funds to the state government, which has the right to promote GC to achieve pollution-free products, so-called green products.

4.2 Institutional barriers and challenges

There are many institutional barriers associated with GC to implement it for pollution-free production. Political issues, lack of policies, taxes, and outdated infrastructure hinder the creation of an effective GC system. Industry and academia are now responding to these challenges and implementing them on a global scale, attracting research funding and moving new, greener chemicals from the research bench to the manufacturing plant. In this implementation, a lack of awareness was observed in education in schools, universities and companies, and in management perceptions [31]. In the implementation, GC are important to bring the laboratory experiment to industrialization. Beyond these barriers, the region faces several other constraints, including a lack of coordination, transport dependency, aging infrastructure, operational limitations, and a broader public and industrial perception problem. Another major obstacle is the successful implementation of new synthesis technologies and corresponding new process technologies, especially in the pharmaceutical industry where US FDA and other documentation pose challenges over time. With such institutional and organizational obstacles, international agencies and national governments need to set up appropriate institutional structures to reduce process time, but also try to avoid disruption from frequent institutional changes. The lack of a common environmental objective across the different institutions can represent a significant obstacle to implementation.

4.3 Technological barriers and challenges

Innovation technology and management integration is the task of the coming century to overcome environmental barriers through the synthesis of green products, so that green economics becomes the driving force behind new products and processes. To implement technology in GC to achieve green production, aspects must be multidisciplinary and not specific. The reasons for this are lack of knowledge about toxicity among chemists and vice versa, the knowledge of laboratory chemists and industrial chemists differs depending on experience and finally, there is no such database of chemical lists and process lists that could help the chemist to establish a product. This is because the industry is unwilling to share information about the chemicals used in production and synthesis processes. As a result, the many substances, hazard characteristics and processes remain unknown. There are no clear design guidelines for researchers in the early discovery phases of GC as there is no communication gap between scientists and engineers. A concerted research initiative by industry, government and academia is required to develop a wide range of reliable, harmless methods available when needed. As part of this initiative, the Crystal Faraday Partnership was established in the UK, where the research forum is funded by both industry and government to promote research, education and dissemination in green chemistry and processing [32]. In this way, the last technical hurdle of the data and information gap was overcome. Still, there are many gaps in knowledge sharing that pose barriers to implementing GC and GT to achieve cleaner production.

4.4 Financial barriers and challenges

GC represents a major cultural change in the way chemicals are developed and materials and products are manufactured. This practice focuses on building a workforce of trained chemists with specializations in toxicology, GC principles, and environmental sustainability. But the investment and promotion of state institutions is not part of the mainstream. In most cases, the benefits of GC accrue directly to the public rather than to an individual company. Therefore, the design of the investment must be such that the impact on the business unit can be reduced, so that new investments for the modernization of traditional units can be easily justified in a profitable way without sacrificing efficiency and quality. In the pharmaceutical industry and for companies with large capital investments, the cost of shutting down an old facility is so high that companies do not have the resources to subsequently reinvest in new technology. In this type of industry, large reactors were used to produce fine chemicals, causing energy losses, solvent losses, and resource losses [33]. This is the type of case where a greener process could easily be deployed, but the companies are tied to the facility, US FDA approval, and a lot more paperwork. Such a situation is not limited to the pharmaceutical industry, but specialty chemicals and all kinds of chemical manufacturing industries also have to overcome such hurdles [34]. Just in the event that the company is able to decommission the old infrastructure, the company could face a potential financial drain that makes maintaining the status quo much more attractive than investing in new infrastructure.

4.5 Public support

The implementation of GC was not only related to chemists and companies, but also to the participation of the general public. While GC has made initial strides, chemists and all are misunderstood as a school curriculum and part of the environmental agenda for washing and cleaning pollutants and waste. On the other hand, due to lack of awareness and the like, they do not have much idea that this new stream is of use to them and brings many benefits [34]. In this scenario, the general public is far from understanding the benefits of GC and does not accept the costly and less effective products that are environmentally friendly. Another major obstacle arose when the public began to consider separating academia and industry, and this concept restricted only the publication of peer-reviewed articles and not industrial research. There are major obstacles in the public sphere regarding highly innovative industries where technology and demand are changing rapidly due to changing fashions and requirements. Without public support in the industry, there are significant obstacles to the implementation of GC. The state police must sensitize the public to waste management and recycling concepts in order to achieve acceptance and many successful implementations of the policy. Therefore, raising public awareness is very important, and in addition to raising public awareness, the public must also be involved in policy formulation to create visions for the future.

5. Strategies to build GC

To promote GC for non-toxic manufacturing, the Green Chemistry Commerce Council (GC3) was formed in 2005 to advance this growing field by bringing together key business leaders, governments, experts, academic researchers, and environmental and health advocates [35]. The philosophy of GC3 is that challenges in exploring, adopting and scaling GC are most effectively solved through cross-industry dialog, collaboration and supply chain partnerships [36]. Five key strategies have been developed to implement GC: enhancing market dynamics, supporting smart policies, fostering collaboration, and informing the market and tracking progress. However, this approach to address the increased GC demands requires an additional new approach, namely P-A-S (Prevention, Assurance and Sustainability) proposed by Chen et al. is suggested [1]. As such, there is a shared responsibility in implementing the 12 GC Principles that can help achieve environmental sustainability, i.e. (1) Prevention of pollution and accident; (2) Assurance of safety and security; (3) Sustainability of energy and resource. This PAS strategy was developed by integrating the first word of the each three parts. Figure 6 shows the incorporation of 12 GC principles and international movements according to PAS strategies. It can be seen that waste prevention (#1), less hazardous chemical synthesis (#3), and reduced derivatives (#8) are core component of the prevention strategy, meanwhile design for safer chemicals (#4), real-time analysis of pollutants (#11), and accident prevention (#12) are core component of the assurance strategy; and atom economy (#2), design for energy efficiency (#6), and renewable feedstock (#7) are core component of the sustainable strategy. Moreover, principles #5, #9 and #10, namely safer solvent and auxiliaries, catalysis and design for degradation, are hybrid components of prevention and assurance; assurance and sustainability, and sustainability and prevention, respectively. In addition, Figure 6 shows the list of international movements categorized by PAS strategies. This new approach is a potential tool that can be used in government, industry and educational institutions around the world to mitigate global sustainability issues. After building these three strategies, three short-term goals need to be set, namely: (1) scaling GC innovation; (2) increase the importance of GC in daily life by accepting the concept; and (3) develop and adopt smart policies that can support industry, research and innovation. In that regard, innovation technology and integration management have also been brought together with these strategies to strengthen PAS strategies.

Figure 6.

PAS strategies incorporated in 12 green chemistry principles and international movements.

6. Innovation technologies

Innovation technology in GC offers opportunities to discover and apply new synthetic approaches using alternative starting materials; environmentally friendly reaction conditions, energy minimization and the development of less toxic and inherently safer chemicals [28]. In the nineteenth century, environmental protocols changed and the LeBlanc soda process was redesigned to be more environmentally friendly. This was the first noticeable change towards cleaner production to get an environmentally friendly product. Apart from this process, the Montreal Protocol calls for replacing the chlorofluorocarbon compound to protect the ozone layer. Waste greenhouse gases such as N2O were used in the production of phenol. In addition, tetrakis(hydroxymethyl)phosphonium phosphate is used as a low-dose agent to combat microbial growth in industrial refrigeration systems with low toxicity.

6.1 CO₂ utilization for the production of valuable fuel/chemicals (air pollution)

Harnessing the emissions of CO₂ into the atmosphere is one of the key elements in controlling global warming. There are various methods, namely direct use by microalgae, conversion to chemicals, conversion to energy, and use by solar energy as fuel. The use of CO₂ to form glucose (Figure 7a) and carbonization products has been observed in nature and in industry, respectively (Figure 7b). Through this technology, valuable chemicals were converted or used in an indirect conversion process. However, a conversion to fuel from direct CO₂ is still being examined. Inspired by natural photosynthesis, systems for the production of artificial solar fuels are now being developed and their efficiency tested. Glutamic acid has been used as one of the conversions for solar fuel (Figure 7c) [26]. Similarly, the enzymes FDH, AlDH, and ADH along with NADPH have been used for the conversion of solar fuels, which represent the formation of format and CO by FDH reductase. However, the conversion still takes place in an aqueous phase rather than in the air, so the solar fuel conversion system was developed (Figure 7d). Laser light was used in the system to initiate the photoreaction and successful stepwise conversion was achieved, for example, of formic acid from adsorbed CO₂, formaldehyde from converted formic acid, and methanol from converted formaldehyde.

Figure 7.

CO₂ utilization in (a) nature plant, (b) high gravity rotating pack system, (c) multi-enzyme system, and (d) solar fuel mechanism.

6.2 Green solvent technology (water pollution)

Many of the industrial manufacturing and laboratory syntheses have changed their manufacturing process to a catalyst-free, solvent-free and safe synthesis. As a result, many named reactions, multicomponent reactions and the heterocyclic compounds in water and on water, are switched to catalyst-free reactions by microwave irradiation and ultrasonic irradiation. In addition, ionic liquids are materials that have attracted significant attention in the scientific community due to their biodegradability, green nature, and environmental considerations, including negligible volatility, nonflammability, and stability (thermal, chemical, and electrochemical). Other solvents such as supercritical fluids (CO₂ and water) have been used as alternative solvents due to their lower critical constant, non-toxicity, and inexpensive nature. Supercritical CO₂ is able to separate low-volatile, higher-molecular and/or more polar compounds with increasing pressure. Apart from these solvents, solvents can be derived from natural compounds and replace petroleum-based solvents. This concept won 22 Presidential Green Chemistry Awards between 1996 and 2014 for approaches that reduce the use of traditional solvents, including alternative, more environmentally friendly solvents [36], and processes that use carbon dioxide and water or eliminate the use of solvents entirely.

6.3 Greener electrochemical storage systems (batteries)

As the shell of the earth, the soil is the most important part of the earth as most human activities are closely related to soils. Stabilizing agents have been developed to promote adsorption, complexation and precipitation to stabilize heavy metal effluent. In general, lime, zeolite, minerals, mining waste, soil, clay, and biochar have been used to control heavy metal accumulation [37]. Many green modifiers have been developed to effectively immobilize lead, zinc, copper and cadmium in contaminated soils, thereby significantly reducing the bioavailability of pollutants. Cultivated treatment wetlands, phytoremediation and bio-retention are the applicability of this type of bio-accumulated modified filler to improve soil and water quality. In the engineered wetland, saturated substrate, vegetation, and microbes were used to mimic the natural wetland. Here, green chemistry approaches were applied to improve the adsorption quality through sedimentation, plant uptake and filtration mechanism. This green wetland also has the potential to biodegrade pollutants into non-toxic forms, be adsorbed by wetland plants, adsorbed onto the adsorption surfaces, or chemically converted to be stored in the wetland matrix. This system offers advantages over traditional mechanisms in terms of cost efficiency due to locally available materials, no additional environmental concerns and is easy to build. This is the area of GC that requires the highest level of innovation to deliver the next generation of innovations in support of a sustainable environment.

7. Integrated management

GC management activities can be divided into three types: (a) cleaner laboratory practice, (b) cleaner production, and (c) sustainable consumption [29]. Clean laboratory practices are behaviors and education aimed at creating more environmentally friendly methods of laboratory work in order to avoid major environmental damage in large-scale production. To achieve this, it is necessary to discuss how the GC approach can effectively minimize hazardous waste in science by including such subjects or courses in curricula. Today, “pollutant-free production” means more environmentally friendly product manufacture in a broader sense with fewer dangerous emissions. When it comes to cleaner production, there are two important aspects to consider, namely industrial ecology and the life cycle of materials. To achieve this goal, several agencies, namely the Green Chemistry Institute (GCI) in the US, the Green Chemistry Network (GCN) in the UK, and the Green and Sustainable Chemistry Network in Japan, are working to bridge the gap between science and academia to close. The manufacturing company suggests sharing knowledge. Not only must management achieve this through cleaner manufactured products, but it can also be achieved through a greener application of the supply chain through to the end use of the product. After manufacturing the product, sustainable consumption is very important, taking into account the need for chemicals, so there is no alternative. Therefore, the safety of chemicals is less important than the need and justification for chemicals having an impact on the environment. This is how green business and cross-industry cooperation must take place. So consumption is just as important as production. All three things above are divided into three levels of management where laboratory practice, production and consumption take place respectively at micro, meso and macro levels.

8. Case studies

8.1 Newlight technologies (air pollution)

Newlight technologies developed AirCarbon, a commercial carbon capture technology that creates AirCarbon by combining methane with air. Basically, AirCarbon is a thermoplastic high-performance material. This technology works at ambient temperature, with the developed catalyst combining air with methane-based carbon to produce thermoplastic materials [38]. In general, most of the technologies available on the market capture CO₂ and produce plastic, but the production costs are significantly higher than petroleum products. To overcome this obstacle, Newlight developed a biocatalyst and method to deactivate the negative receptors on polyhydroxyalkanoate polymers and produce inexpensive and highly efficient catalysts for plastic production. This is the main polymer-producing enzyme in the biocatalyst, capable of polymerizing 9 kg of polymer per 1 kg of biocatalyst used. In this way, methanol is used, which is responsible for capturing the radiation. The carbon negative plastics have been used to manufacture many useful products such as plastic bags, cell phone cases, home accessories and other products. In addition, many leading companies have adopted the AirCarbon product as part of their packaging materials for bags and cell phone cases. By eliminating greenhouse gases, New Light Technologies won the 2016 EPA Presidential Green Chemistry Challenge Award for pollution-free manufacturing.

8.2 Pfizer Inc. (water pollution)

Zoloft, the most prescribed drug for depression, is consumed annually in the United States, valued at $43.7 billion. Pfizer pioneered production using sertraline as the active ingredient, which was synthesized in a three-step process during the original manufacturing process and reduced to a single step in the new process [39]. In the traditional process, hydrolysis, decarboxylation, Friedel Crafts acylation, condensation, and catalytic reduction of the imine gave a mixture of cis and trans amines. Pfizer improved its manufacturing process, in which cis- and trans-sertraline were obtained by imine formation of monomethyl mine with a tetralone, followed by reduction of the imine function and in situ resolution of the diastereomeric salts of mandelic acid. The product obtained has a higher yield and a higher selectivity. In addition, a palladium catalyst was introduced in the reduction step to reduce impurities and decrease raw material consumption by 60, 40 and 20% for monomethyl amine, tetralone and mandelic acid, respectively. The implementation will save 220,000 pounds of 50% caustic soda, 330,000 pounds of 35% hydrochloric acid waste and 970,000 pounds of titanium dioxide waste annually. By eliminating waste, reducing solvents, and maximizing yields of key intermediates, Pfizer won the 2002 EPA Presidential Green Chemistry Challenge Award for Cleaner Manufacturing.

8.3 Dow AgroSciences LLC (soil pollution)

As the world population increases, so does the demand for higher crop yields, and with it the negative impact of agricultural activities on the global environment. About 75% of nitrates in the environment, for example in soil and water, come from the application of nitrogen fertilizers and manure. Basically, soil bacteria rapidly metabolize the nitrogen from the applied urea and fertilizer, resulting in less availability of nitrogen for plant nutrition. To overcome this barrier, DOW Chemical scientists are developing an aqueous microcapsule suspension product, instinct, a nitrification inhibitor to prevent nitrogen conversion from urea. Based on calculations, the use of this product reduced estimated carbon dioxide equivalent emissions by 664,000 tons and increased corn production by 50 million bushels. By eliminating toxic chemicals and CO₂, Dow Agro Chemical won the 2016 EPA Presidential Green Chemistry Challenge Award as part of a cleaner manufacturing mission.

9. Conclusion

Overall, this review has discussed the basic concept of GC and 12 principles with their application to the development of pollution free products. Along with the Principles, the associated barriers to the implementation of the GC Principles were discussed. Furthermore, this paper has also highlighted the role of PAS strategies, Prevention, Assurance and Sustainability to meet the requirements to overcome the associated barriers. In summary, the role of innovation technology and integration management would play in building GC was extensively discussed. In addition, this overview discusses the industrial case study related to the control of air, water and soil pollution by implementing the GC concept. Although the strategy discussed in this chapter is simple, it arouses enough interest among researchers to take the next step in implementing GC for a sustainable environment.