Circular Chemistry: An Enabler of Circular Economy To Achieve the Zero-Waste Goal

Dedication

This article is dedicated to Dr. Praveen Kumar Tandon, Professor (Former Head), Department of Chemistry, University of Allahabad, on his 67th Birth Anniversary as a token of respect for his remarkable contribution to the field of catalysis and chemical kinetics.

Abstract

The main aims of zero-waste goals are the promotion of sustainable production and consumption through the societal move toward circular approaches. The chemical industry includes a variety of processes to produce various useful consumables, but many of these processes have serious negative environmental, health, and safety impacts at every level of their design, production, processing, and uses. Circularity is at the core of eco-design and the production technology in which waste is repurposed and their environmental impacts are reduced via the 3Rs concepts: reduce, reuse, and recycle. The integration of circular approaches with chemistry makes it a circular chemistry (CC). This article provides a brief literature review on CC and why it is important to tackle the various sustainability-related issues. Here we conduct a structured opinion as well as evidence-based review to explore the role of CC to make it more sustainable. Fundamental aspects of CC and its role in the circular economy have been discussed, and it is concluded that the design of clean chemical processes, recovery, and reuse of wastes, and reintroducing recovered materials back to the industrial production chain is possible and scalable. This article aligns with 7 UN’s Sustainable Development Goals, that is, 3, 6, 9, 12, 13, 14, and 15.

 

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Keywords

Circular chemistry - Zero-waste goal - Circular economy - Sustainability - Circularity - Recycle

Significance

Circular chemistry can provide logical solutions to various global challenges and support the circular economy for sustainable development. This study focused on the integration of circular approaches in chemistry and its related practices with a clear motive to reduce the production of chemical wastes and optimize resource efficiency by reducing, reusing, and recycling (3Rs). Thus, this article aligns with 07 UN’s Sustainable Development Goals (SDGs), that is, SDG 3, 6, 9, 12, 13, 14, and 15. True sustainability comes through the applications of circular approaches only.

1

Introduction

In 2015, the 2030 Agenda for Sustainable Development was adopted by all the members of the United Nations, which sketched a detailed outline and plan for prosperity and peace for peoples and the earth not only for the present but also for the future. This agenda includes a plan of action for people to maintain peace, prosperity, and symbiotic partnerships on this planet to sustain the life with beauty of natural biodiversity [1], [2]. Nature has a unique work culture, that is, material cyclization and resilience to maintain its sustainability, and it is the source of inspiration behind many of the innovative acts of human beings [3]. Humans observe and learn everything from nature by mimicking. Nature maintains its sustainability through circular approaches [4]. Nature sustains all forms of life and its own resources from millions of years by circular processes, that is, biogeochemical cycles. Due to this unique feature, that is, true circularity, nature produces no waste and continuously works on a zero-waste strategy. Zero-waste goal (ZWG) is a global initiative to treat discarded materials (i.e., waste) as resources that can be returned back to nature/marketplace to be reused again and again and thus reduce waste production at its minimal level via reducing, reusing, and recycling (3Rs) [5], [6], [7]. It is a key pillar of the movement for environmental justice. ZWG is the integral paradigm toward the achievement of circular economy (CE). The CE is a model where materials are kept in circulation via 3Rs for their optimal use. In recent years, CE has become an emerging field of sustainability due to its capability to conserve and regenerate natural resources [8], [9]. The Application of CE principles in chemistry and its related practices are the only promising solutions to the environmental and sustainability-related challenges of the chemical industry. Waste is an invention of humans and is now treated as one most horrible challenges for the world. According to the recently published United Nations Environment Programme (UNEP) report 2024, municipal solid waste (MSW) production is expected to grow from 2.1 billion tonnes in 2023 to 3.8 billion tonnes by 2050 [10]. The global direct expenditure of waste management was estimated at about 252 billion USD in 2020. Total global cost is expected to rise up to 361 billion USD when other hidden costs of pollution, climate change, health issues, etc. which are directly or indirectly associated with improper waste management are included [10]. Without taking serious steps toward waste management, it is expected that the total annual cost could be doubled by about 640.3 billion USD. Only by a drastic reduction in waste production, proper waste management, and following concepts of CE (i.e., way to use waste as a resource), we can secure an affordable, livable, and sustainable future. Waste is the one of the main source of various hazardous chemicals, that is, heavy metals (i.e., Pb, Cd, Hg, Ni, Zn, Cr, As, Cu, etc. are present in waste obtained from pesticides, dyes, catalysts, electronic devices, medicines, paints, printing materials, industrial sludge, and incineration of household wastes) [11], [12], volatile organic compounds (VOCs, i.e., benzene, toluene, ethylbenzene, xylenes, etc. are organic pollutants affecting human health and atmospheric chemistry and are released from wastes containing paints, solvents, cleaners, degreasers, dyes, varnishes, refrigerants, household wastes, and also from plastics, e-wastes, and incineration of wastes) [13], [14], persistent organic pollutants (POPs, i.e., polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, etc. are chemicals with minimum degradation capability in the environment, high accumulation in animal/human tissues and able to transmit through food chain), etc [15], [16]. Integration of circular approaches in chemical science and its related field of research and development, that is, CE in design of new products [17], sustainable circular uses of chemicals [18], CE for chemicals in plastics [19], CE-based design for research and development in the field of chemical science [20], role of CE in a sustainability framework [21], and CE perspective of plastic value chain [22] have great potentials to solve the world’s chemical waste problems. By replacing linear approaches (i.e., take-make-use-dispose) with circular approaches (i.e., take-make-use-reuse-recycle-retake-…), waste generation, as well as pollution [23], can be minimized. Thus, circular approaches like circular chemistry (CC) contribute toward a circular economy—a system where material never becomes waste just similar to nature like recyclable plastics in CE [24], degradable and chemically recyclable polymers [25], CE implications of recycled PET [26], sustainable chemistry by circular design [27], and circular model of recycling plasmix [28]. Thus, circular chemistry (CC) has great capability to solve the various challenges related to the chemical industry. Although CC has gained the attention of researchers worldwide [8], [18], [27], [29], [30], [31], [32], still it requires more attention to popularize the concepts of circular chemistry among nonfield specific researchers. In this context, the present article briefly reviewed the fundamental aspects of CC with respect to ZWG and CE to overcome the global challenges associated with chemistry as an enabler of CE to achieve the ZWG. Humankind is facing various challenges regarding sustainability, that is, the ability to sustain our environment, ecosystem, civilization, and humanity on this blue planet. It is expected that rampant growth in the human population and related developmental activities will intensify these challenges much more in the near future. The ways to tackle these challenges should be cost-effective, simple, and sustainable. Therefore, the development of circular processes (circular chemistry, CE, etc.) mimicking the biological life cycle is crucial to achieving a more sustainable future. To explore the role of circular approaches in chemical processes to optimize the resources for their sustainable use. This study can address the limitations of linear approaches and their environmental impacts and is also able to explore the application of circular approaches in chemistry. Thus, the scope of sustainability may be expanded to the entire lifecycle of chemical materials.

1.1

Waste

Waste can be understood as an unwanted matter in place and time and first time described in the 12th century [33]. There is no waste in nature. One organism’s waste is another’s resource in a natural ecosystem. Waste is considered a precious resource in the natural ecosystem, while in the anthropogenic ecosystem, waste (i.e., human invention) is considered one of the world’s main ecociders. As a result of uncontrolled and rampant growth in the world’s population, waste production has increased about tenfold, and it is expected that it should double again by 2025 [34]. Annually, about 7–10 billion tonnes of anthropogenic waste are generated globally [15], [35], including 300–500 million of tonnes waste labeled as municipal solid waste [36] and hazardous wastes [37], [38], that is, toxic, explosive, flammable, corrosive, etc.

 

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1.2

Zero-Waste Goals

ZWGs are defined as the conservation of natural resources by reasonable and responsible production, use, reuse, and recycling of materials. United Nations declared 30 March as International Day of Zero-Waste to explore the impact of ZWGs. The main aims of ZWGs are the promotion of sustainable production and consumption which support the societal move toward circular approaches and enhance the awareness about how zero-waste goals contribute toward the 2030 Agenda for Sustainable Development. ZWGs are the integral paradigm toward the achievement of CE or circularity throughout the world [5], [6], [7]. To achieve ZWGs, actions are required at all levels, that is, (i) the product should be designed to be durable and reusable with less environmental impact, (ii) resource-efficient methods, (iii) sustainable and economic transportation, (iv) managed demand can enable zero-waste throughout the life cycle of a product, (v) consumer can play a pivotal role toward zero-waste by reuse and repair of products as much as possible before proper disposal, and (vi) the government, communities, and industries can play their role by improving waste management and recovery system through better policymaking [39] ([Fig. 1]).

Figure 1 ZWGs: action is required at all levels.

 

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1.3

Sustainable Development and Sustainability

Life on Earth is the epitome of resilience, adapting and changing to fit its context over billions of years. Understand true sustainability from nature itself—not only creating but also continuing to nourish and heal the systems that create conditions conducive to life. Demand for basic amenities including food, shelter, health, and energy resources increases continuously due to rampant growth in the world’s population and the rise in living standards of human beings. The existing and more popular linear approach/economy poses significant threats to human health and the environment through resource depletion and waste production in huge amounts. To overcome all these global challenges, the closed loop, restoring, and waste-free (zero-waste) concept, that is, CE has gained worldwide acceptance to achieve the goal of sustainability. CE is a part of emerging science, that is, industrial ecology, which is very crucial for sustainable development. The CE is also known as sustainable economy where economic growth is associated with reduction of resource consumption and recirculation of natural resources [40], [41], [42], [43], [44]. The main goal of sustainability is to encourage and inspire people to explore a new way of looking at themselves as well as the world. Thus, true sustainability comes through circularity [23]. Circularity is at the core of eco-design, the production technology in which waste is repurposed and environmental impacts such as raw material consumption are reduced via 3R concepts: reduce, reuse, and recycling.

 

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1.4

Linear and Circular Approach

The linear approach includes take-make-use-and-dispose, therefore generating a huge amount of waste materials to contaminate the environment. Linear approaches are a major cause of environmental degradation. It causes resource constraints and thus affects economic growth. Circular approaches can overcome these disadvantages of linear approaches. Circular approaches include take, make, use, recollect, repair, reuse, and recycle the materials to create a close cyclic system to minimize the intake of natural resources as well as the generation of wastes. Thus, circular approaches can help to restore the regenerative capacity of an ecosystem to conserve resources. [Fig. 2] provides a schematic comparison between linear and circular approaches [23].

Figure 2 Linear versus circular approach.

 

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1.5

Need for Circular Approach

Circular approaches are essential to solve the imminent challenges related to environmental degradation and exhausting natural resources. Recently, CE has attracted a lot of attention from research communities worldwide due to its significance and contribution toward sustainable development goals [45]. The concept of CE has become more popular due to its applicability toward environmental sustainability and ZWGs [46]. The functioning of CE is based on the principles, that is, rethink, reduce, reuse, recover, recycle, redesign, repurposing, etc. to conserve natural resources [47]. CE is based on the concept of ‘zero-waste’ which can be achieved only by circular approaches. Thus, circular approaches may play a very important role in the CE [18], [48]. There are various indicators or business activities that can be used to access the transition to the CE in terms of resource efficiency (i.e., reduction in ecological footprint in production inputs/infrastructure, reduction in pollution product use/production process, reduction in raw material use in production, optimization of warehouse concept to reduce storage space, etc.), closing the resource loop (i.e., increase in reuse of production inputs/infrastructure, facilitation for recycling, reuse of waste and residual materials inside or outside the company, expansion of the facility to use sharing platforms, refunds on product returns, resale/upgrade of returned products, etc.), and increasing product life (i.e., purchase of infrastructure with a long product life, increase the life span of infrastructure by maintenance and repair, expansion of product life, facilitate the repair during use, extend warranty and repair services, improve spare parts accessibility, etc.) [49].

 

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1.6

Methodologies To Assess the Circularity

Measurement of the circularity of the chemical industry involves the assessment of its progress toward a CE. There are various tools and metrics that are more frequently used in the measurement of circularity, that is, MCI (Material Circularity Index: measures the production of recycled materials) [50], CEI (Circular Economy Index: assess waste reduction, recyclability, and resource efficiency), LCA (Life Cycle Assessment: assessment of environmental impacts throughout the value chain, MFA (Material Flow Analysis: measure material flows and stocks), rate of recyclization, waste reduction rate, carbon footprint, circular use of water, use of renewable energy, etc. [43], [51], [52] Various indicators like the ratio of recycled materials used at a production level, the percent reduction in generation of hazardous/toxic waste, reduction in water consumption, etc. are also used to assess/measure the circularity of a process with a particular system. [53] Chemical industries can measure and improve their level of circularity by using the above metrics/methodologies and indicators to contribute toward a more sustainable future.

 

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2

Circular Chemistry

CC is an emerging and innovative approach to make chemical practices more sustainable and truly circular. CC aims to replace today’s linear approach with a new circular approach for optimizing resource efficiency and preserving finite natural resources. Thus, CC can play a very crucial role in achieving the ZWG, which ultimately contributes to a CE (i.e., all activities of the 3Rs concept in manufacturing, supply, and consumption of products). Chemistry can act as a proponent of sustainability via sustainable development to provide ethical, sustainable, and practical solutions to global challenges by catalyzing radical reforms in the chemical industry. Catalysis is one of the key principles of green chemistry and can play a very important role in CC by enhancing the regeneration and reuse of catalytic materials [23],[54], [55], [56], [57], [58], [59], [60]. Catalyzed processes are involved in the production of about 90% of products in the chemical industry [61]. Catalyzed processes produce a huge amount of catalytic materials as waste after their end-use. Regeneration and reuse of catalytic materials can increase the total resource efficiency of catalysts and also enable a closed loop for circular use of precious noble metals (as noble metals are precious and too costly). Thus, catalysts play a pivotal role in our pursuit of CC [62].

2.1

Nature and Circularity

Nature has worked on zero-waste strategy for millions of millions of years. Nature is regenerative as it reuses and recycles the nutrients to generate new raw materials; thus, there is no waste in nature. [Fig. 3] schematically shows the true circularity of nature as a nutrient cycle (a vital natural service)—the circulation of matter essential for life from the environment (mostly from soil or water) through the biotic kingdom (living organism) back to the environment [63]. [Fig. 3] explains a completely closed loop for cyclization of organic matters from biotic to abiotic kingdom and vice versa. The nutrient cycles are real examples of the true circularity of nature. Carbon, nitrogen, sulfur, phosphorous, and water are among the essential elements that move through biotic, earth, and atmospheric systems via biogeochemical cycles. Earth is the only known planet in our solar system that has vital conditions (i.e., air, water, soil, fire, and sky) for the survival of life. Maintenance of these vital conditions requires a constant recycling of materials between abiotic (nonliving) to biotic (living) components of ecosystems.

Figure 3 Nutrient cycle in nature: true circularity.

 

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2.2

Chemistry and Global Challenges

Global demands for materials and energy increase continuously due to rampant growth in the world’s population and people’s demand for high quality of life. Humans as well as society could not survive sustainably without chemicals because chemicals have become an integral part of modern society. A number of chemicals are essential parts of our daily life needs and very crucial for economic and societal sectors also. Many of these chemicals are hazardous in nature and have great potential to harm living beings and environmental biodiversity. The chemical industry has serious negative environmental, health, and safety impacts at every level of chemical production and its uses [64], [65]. [Table 1] summarizes some selected hazardous chemicals and their impacts on human health [66].

Table 1 Some selected chemicals and their adverse effects on human health.

S. no.	Chemicals	Adverse health effects
a Secondhand smoke is a mixture of smoke exhaled by a smoker that is diluted by the surrounding air (main stream smoke) and the smoke from the burning tip of a cigarette or other smoked tobacco product (side stream smoke).
1	Lead	Neuro-disorders, intellectual disability, cardiovascular disease (IHD, ischemic heart disease), stroke, etc.
2	Pesticides	Parkinson’s disease, the cause of suicide by self-poisoning of pesticides, etc.
3	Ambient air pollutants PM (particulate matter), SO x (sulfur dioxides), NO x (nitrogen oxides), benzene, benzo[α-]pyrene, etc.	ALRI (acute lower respiratory infections, i.e., pneumonia, bronchitis, and bronchiolitis), upper respiratory infections and otitis media (middle ear infection), IHD, adverse pregnancy outcomes (i.e., low birth weight, prematurity, and stillbirths), COPD (chronic obstructive pulmonary disease), asthma, lung cancer, stroke, etc.
4	Household air pollutants CO (carbon monoxide), SO x , NO x , C6H6, HCHO, poly-aromatic hydrocarbons (PAHs), PM, etc.	COPD, cataracts (an important cause of blindness worldwide), ALRI, IHD, otitis, lung cancer, stroke, etc.
5	Second-hand smokea Nicotine, HCHO, CO, phenols, NO x , naphthalene, tar, nitrosamine, PAHs, vinyl chloride, metals, HCN, NH3, etc.	ALRI, IHD, otitis, lung cancer, stroke, etc.
6	Chemicals in occupational exposure As, asbestos, Be, Cd, Cr, diesel exhaust, Ni, silica, C6H6, ethylene oxide, ionizing radiation, dust, fumes/gas, etc.	Leukemia (blood cancer), COPD, trachea, bronchus, lung cancer, etc.

Improper handling and management of chemicals and related wastes severely damaged our life support systems, that is, air, water, and soil. As a result of these, chemicals enter the food chain and affect living beings [67]. Chemistry has great potential to address the various human challenges related to their sustainable survivability and plays a direct and dynamic role at the interface of science, society, and policy. Thus, chemistry plays the role of central science. It is crucial to understand life, environment, economy, society, technology, etc. [68], [69] Global Chemicals Outlook II, which was electronically launched on April 29, 2019, in Geneva, Switzerland, as a working document to give innovative solutions to minimize the adverse environmental, health and safety effects of chemicals and its related wastes and for implementation of 2030 agenda of sustainable development mandated by UNEA (United Nation Environmental Assembly), 2016. The report highlights that the global goal to minimize the adverse effects of chemicals and wastes needs urgent attention and more ambitious worldwide action by all stakeholders [65]. Global trends, that is, population growth, economic growth, and urbanization are rapidly increasing the consumption of chemicals. By 2030, it is estimated that the chemical industry's worth (market size) would have doubled its worth in 2017. Whether this growth will show its positive or negative impact on the biotic kingdom, including humanity, only depends on how chemicals and their related challenges are managed. Toxic and hazardous chemicals continuously pass into the surroundings (environment), contaminating food cycles and finally entering living beings where they cause severe damage. Recently, the World Health Organization (WHO) estimated that about 2 billion lives and 53 billion disability-adjusted life-years were lost in the year 2019 due to exposure to selected toxic/hazardous chemicals [66]. [Fig. 4] explains the merits and demerits of the chemical industry and possible solutions to reduce its adverse effects on the ecosystem.

Figure 4 Economical and environmental perspectives of the chemical industry.

 

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2.3

Concepts of CC

The application of circular approaches in chemistry by which materials/chemicals are continuously cycled back through the value chain for reuse, thereby optimizing resource efficiency and preserving finite natural resources is known as CC. Thus, the scope of sustainability may be expanded to the entire lifecycle of chemicals. CC can optimize resource efficiency and enable a closed loop for an environmentally benign chemical industry [23]. CC can solve various challenges associated with the chemical industry from an environmental perspective. Twelve basic principles of CC and their sustainability aspects are briefly presented in [Table 2], [29], [32].

Table 2 The 12 principles of CC and their sustainability aspects.

S. no.	Principles of circular chemistry	Brief explanation	Sustainability aspects
1	Collect and reuse the waste	Reusing waste as a resource is a necessary prerequisite for enabling circularity of elements, molecules, and materials	An economic and environmental perspective of sustainability is directly linked to the way in which we extract, process and consume the earth’s finite natural resources. This can include conservation of natural resources, making sustainable products by adopting circular approaches (mainly recyclability) in product design, changing consumption behavior, and incorporating more sustainable business models to favor the circular economy (CE). The circular economy is a key enabler to achieving the objectives of UN SDGs, i.e., reducing inequality, improving health and education, peace and prosperity for all, protecting environment, etc. Proper management of chemicals and related waste is a specific target 12.4 under SDG 12. It is also referred to under good health and well-being (SDG 3), clean water and sanitation (SDG 6), industry innovation and infrastructure (SDG 9), climate change (SDG 13), life below water (SDG 14), and life on land (SDG 15) Reuse is the second important strategy of 3Rs concept for waste management after the waste reduction. It is the process of using a material over and over period of time. It preserves energy and material both. Thus, it favors SDG 12, i.e., responsible consumption and production, and targets 12.2 & 12.5
2	Maximize atom circulation	Truly circular chemical process platforms should maximize every atom in existing molecules
3	Optimize resource efficiency	Resource conservation should be targeted, promoting reuse, and preserving finite feedstocks
4	Strive for energy persistence	Energy efficiency should be maximized
5	Enhance process efficiency	Continuous innovations are required to promote the reuse and recycle of materials during the process (in-process) and repurposing of used materials (post-process) preferably on the site by reducing the consumption of raw materials and by optimizing resource production.
6	No out-of-plant toxicity	Chemical processes should not release any toxic compounds into the environment
7	Target optimal design	Design should be based on the highest end-of-life options, accounting for separation, purification, and degradation
8	Assess sustainability	Environmental assessment (by life cycle assessment) should become prevalent to identify inefficiencies in chemical processes
9	Apply ladder of circularity	The end-of-life options for a product should strive for the highest possibilities on the ladder of circularity
10	Sell service rather than product	Producers should employ service-based business models such as chemical leasing, promoting efficiency over production rate
11	Reject lock-in	The business and regulatory environment should be flexible to allow the implementation of innovations
12	Unify industry and provide coherent policy framework	The industry and policy should be unified to create an optimal environment to enable circularity in chemical industry

The principles of green chemistry were introduced by Paul Anastas and N. Eghbali in the year 2010 to make chemical processes/products greener or more environmentally friendly [70]. The principles were mainly developed to prevent the production of pollutants at their source by minimizing the use of hazardous chemicals. In the year 2003, Anastas and Zimmerman published 12 principles of green engineering mainly focusing on how to achieve sustainability through science and technology [71]. The main objective of these principles of green engineering was to provide new human, health, and environment benign materials/products/processes through the synergetic engagement of scientists and engineers. In 2019, Chris Slootweg published a commentary in ‘Nature Chemistry’ and introduced a new concept: CC by presenting 12 principles of CC for a far-reaching reform (revolution) in the practices of chemistry to solve the socioeconomic and environmental challenges of the future [32]. According to Slootweg, “the concept of circular chemistry expands the scope of sustainability to the entire life of chemical products.” CC requires clear objectives at molecular, method, product, and system levels. [Table 3] lists the comparative aspects of the 12 principles of CC, green chemistry, and green engineering [72], [73], [74].

Table 3 Principles of CC, green chemistry, and green engineering.

S. no.	Principles of circular chemistry	Principles of green chemistry	Principles of green engineering
1	Collect and use waste	Prevention	Inherent rather than circumstantial
2	Maximize atom circulation	Atom economy	Prevention instead of treatment
3	Optimize resource efficiency	Less hazardous chemical syntheses	Design for separation
4	Strive for energy persistence	Designing safer chemicals	Maximize efficiency
5	Enhance process efficiency	Safer solvents and auxiliaries	Output-pulled versus input-pushed
6	No out-of-plant toxicity	Design for energy efficiency	Conserve complexity
7	Target optimal design	Use of renewable feedstocks	Durability rather than immortality
8	Assess sustainability	Reduce derivatives	Meet need, minimize excess
9	Apply ladder of circularity	Catalysis	Minimize material diversity
10	Sell service, not product	Design for degradation	Integrate material and energy flows
11	Reject lock-in	Real-time analysis for pollution prevention	Design for commercial ‘Afterlife’
12	Unify the industry and provide policy	Inherently safer chemistry for accident prevention	Renewable Rather than Depleting

[Table 3] listed the 12 principles of CC, green chemistry, and green engineering.

 

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Zero-Waste Goal and CC

The proper management of chemical and related wastes is a key point to achieve inclusive, resilient, and sustainable human development while shifting toward CC can eliminate/reduce the production of waste/pollution, optimize the use of products/goods/materials for longer periods and help in regeneration of natural systems. Elhami et al. describe various recovery techniques used for the remediation of various acidic organic pollutants from wastewater by enabling CC approaches [75]. Guarieiro et al. explored the role of CC as a pillar and driver of ZWG to achieve sustainable development for a better future. The transition from chemistry 1.0 to chemistry 4.0 is well explained to explore the application of circular approaches in chemistry to solve various environmental challenges associated with chemical practices/industries [29]. Clark et al. describe the role of chemists in the world without waste and also explain how CE looks toward chemistry for innovative solutions to various global challenges associated with the sustainability of life [20]. Aurisano et al. address the need for technological innovation to separate various constituents of end-used products, that is, more than 6000 additives are used in plastic to provide various properties but cannot be recycled [76]. Slootweg explores the circular role of carbon (C), nitrogen (N), and phosphorous (P) by using waste as a resource to realize a CE. Traditionally, chemistry focused on the linear production model to make useful products but it creates numerous local, global, and environmental challenges that open new roles for chemistry as CC (pillar of sustainable development) [77]. Chemistry may become a better tool if current practices (basically works on linear approaches) are replaced by circular approaches. Integration of CC with biomimetic approaches and green chemistry makes it sustainable chemistry to achieve sustainable development goals, which is schematically illustrated in [Fig. 5].

Figure 5 Schematic route to develop sustainable chemistry.

 

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CE and CC

CE is a multidisciplinary field and has great potential to support the United Nations Sustainable Development Goals. Optimization of utilization or use of manufactured products is the main aspect of CE. Thus, CE differs from a linear industrial economy, which basically focuses on the optimization of the production of products up to the maximum point of sale. CE has been an integral and nonseparable part of human development since the beginning as a strategy to overcome scarcity and poverty. But, in the current age of environmental degradation when we are facing a lot of challenges related to the sustainability of life, the CE becomes a more promising tool to achieve ZWGs for sustainable development. Industrial chemicals are manufactured and marketed worldwide with a global market size of $5079.29 billion in 2023. It grows at a compound annual growth rate (CAGR) of 8.1% from $4700.13 billion in 2022 to $5079.29 billion in 2023 [78]. It is expected that the total market size of the chemistry industry will reach about $6851.59 billion in 2027 at the CAGR 7.8 %. The significance of the chemical industry on the world economy is well reflected by these data [79], [80]. But, due to the linear approach commonly applied in the chemical industry, huge amounts of toxic/hazardous wastes are generated, which adversely affect the quality of our life support systems. As a result of these consequences, we face a lot of global challenges, that is, global warming, acid rain, air pollution, photochemical smog, biomagnification of toxic chemicals in top consumers due to imbalanced and contaminated food cycle, etc. In the search for a scalable methodology to solve these challenges, the economic significance of the chemical industry will be compromised. Therefore, there is an urgent need to apply CC approaches to solve various environmental concerns without affecting the economic importance of the chemical industry and make it a CE for a sustainable future.

 

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Current and Future Perspectives

Almost 96% of all manufactured goods worldwide are directly associated with or influenced by the chemical industry which is pivotal in establishing a sustainable economy. The chemical industry plays a very important role in the global economy and supply chain network. Based on principles of green and CC development of the circular chemical industry is probably the right move toward a sustainable future [81]. Wang et al. offer in-depth progress of both the homogeneous and heterogeneous catalytic processes used in acceptor-less dehydration of biomass-derived glycerol and ethanol toward CC [82]. Lozano and Garcia-Verdugo, explore how circular and green chemistry-based biocatalysts can prove themselves the most important and efficient agents for achieving sustainable development goals [83]. Wolos et al. explore the role of computer-based designs in the development of circular chemical industries. They explained how computers equipped with synthetic knowledge can help to address the challenges associated with chemical wastes. They successfully generate giant synthetic networks by considering 200 waste chemicals recycled and various approaches are validated experimentally also. Adoption of computer-based waste-to-resource algorithms can accelerate product reuse of chemicals to reduce environmental impacts [84]. Osman et al., 2021 very nicely reviewed the various processes, that is, gasification, enzymatic hydrolysis, combustion, pyrolysis, etc. for conversion of biomass to biofuels to solve global energy demand is estimated to rise by 28% up to year 2024 [85]. Ferronato et al., 2023 describes various practical approaches that need to be implemented worldwide to boost the circularity of plastic wastes to make the world plastic free. The article also provided deep insights into social and technical issues related to the implementation of strategies to develop a scalable action plan for the circular use of plastic [86]. Recyclization of materials used in photovoltaic panels, circular agro-environmental processes to manage agricultural wastes, and waste metrics in frameworks of CE are well referred to in the literature [51], [87], [88]. [Fig. 6] describes CC as an enabler of the CE.

Figure 6 CE versus CC.

 

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Conclusions

In our collaborative effort to make the world more sustainable, the integration of circular approaches with chemistry makes the chemical industry environment benign and contributes a lot to the global economy. CC helps in different ways to transform chemical practices from linear to circular. CC and CE are closely related to each other because both strongly recommend the optimization of the utilization of renewable materials and waste. CC acts as an enabler of CE because it helps to increase resource efficiency, the intensity of utilization, product life, recyclability, and efficiency of products, and reduce the generation of waste by decreasing the loss of materials. Thus, waste is treated as a resource and helps to achieve the ZWG. The review explores the basic concepts of CC to find workable solutions to various global challenges that can support the CE for a sustainable future. It is clear from the examples discussed in this review that the design of clean chemical processes, recovery and reuse of wastes, and reintroducing recovered wastes back to the industrial production chain is possible and scalable. The efficient and amazing synergies may be found through the combination of existing technologies with circular approaches and thus can open new paths for the development of new sustainable circular chemical processes based on green processes and circularity of materials to synthesize chemicals and upgraded wastes. Thus, this review will open new dimensions of innovative research and development in the field of CC for a more sustainable society. It also provides a logical and innovative solution for waste management without creating any constraints on resources.

 

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Dr. Santosh Bahadur Singh

Dr. Singh was born in Azamgarh, Utter Pradesh, India, in 1982 and received his undergraduate (UG) and postgraduate (PG) educations from VBS Purvanchal University respectively in 2002 and 2004. After receiving his D.Phil. degree in Chemistry (May 2010) under the supervision of Prof. Praveen Kumar Tandon (a renowned academician in the field of ‘Chemical Kinetics and Catalysis’), Singh pursued his postdoctoral studies at the University of Allahabad (May 2010–June 2015). He started his independent academic/scientific career as a Faculty Member in July 2015 at the Department of Chemistry, National Institute of Technology Raipur, Raipur, Chhattisgarh. Then, he moved and joined the Department of Chemistry, University of Allahabad, as an Assistant Professor (Chemistry) in August 2022. The main objective/mission of Dr. Singh’s laboratory is to educate the students at the intersection of fundamental catalysis-nanocatalysis, physical-organic chemistry, biophysical chemistry, and circular-sustainable chemistry. Singh is trying to develop novel catalytic materials that help to reduce the environmental impact of human activities and make chemical processes more environmentally benign by following circular chemistry concepts. Dr. Singh has published more than 50 articles in international/national journals of high repute with a total impact factor >66, h-index of 13, i10-index of 16, and total citations of 716 [https://scholar.google.co.in/citations?user=8-83bmsAAAAJ&hl=en].

Contributors’ Statement

Sole author: Santosh B. Singh

Conflict of Interest

The author declares that they have no conflict of interest.

Acknowledgments

I am fortunate enough to have two disciplined, sincere, smart, talented, and wonderful sons: Nishant and Divyansh. I am especially privileged to have Mrs. Jaya as my wife, friend, and life associate. My mother is my real hero who has taught me how to live in adverse situations. I dedicate this article to my supervisor Prof. Praveen Kumar Tandon for his selfless efforts to give me all those competencies that helped me a lot to achieve my real goals of life.

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Publication History

Received: 31 August 2024

Accepted after revision: 23 October 2024

Article published online:
22 November 2024