Anastas coined the term "Green Chemistry" for the first time in 1991, in a special program created by the US Environmental Protection Agency (EPA) to stimulate significant development in chemistry and chemical technology. The program also aimed to change chemists' perspectives on environmental protection by focusing on lower risks or their complete elimination in terms of human health. Green chemistry is a chemical research and engineering philosophy that involves the development of products and processes that reduce the use and generation of hazardous chemicals (Pereira, 2020). Unlike environmental chemistry, which studies pollutant chemicals and their effects on the environment, green chemistry seeks to reduce pollution at its source. Green chemistry entails reducing waste at the source, using catalysts instead of reagents, using non-toxic reagents, using renewable resources, increasing atom efficiency, and using solvent-free or recyclable environmentally friendly solvent systems. Green chemistry practices can assist businesses in achieving material and energy efficiency while also reducing hazards throughout the product's life cycle.
Implementation Approaches of Green Chemistry
Green
chemistry strategies are classified into three types on the basis of implementation
time, resources required and implementation risks. Short-term, medium-term and
long-term implementation approaches are all available (FICCI, 2014).
1. Short-term approaches
By
creating zero discharge solutions, lowering the levels of Chemical Oxygen
Demand (COD) and TDS in wastewater generated, and creating collaborative
platforms to learn from other companies' best practices, the industry should
look for ways to optimize their current business practises in the near future.
Zero discharge
solution:
It employs advanced wastewater treatment technologies to recycle, recover, and
re-use the treated wastewater, resulting in the discharge of the bare minimum
of wastewater to the environment. Apart from reducing environmental waste
discharge, it aids in 90-95% water recovery and by-product recovery from salts,
resulting in operational savings.
Reduction in COD
and TDS:
Organic and inorganic contaminants in industrial wastewater make it hazardous
and unsuitable for direct biological treatment. Industrial effluents need to be
treated in order to meet requirements for disposal or recycling. COD can be
decreased using a variety of techniques, including the use of hydrogen peroxide
(H2O2), isolated microorganisms, subcritical water oxidation, thermal-liquid
phase oxidation and adsorbents including fly ash, activated carbon, neem leaves
etc.
Collaborative
platforms:
Instead of competing, companies can learn from the best practices prevalent in
other companies by establishing collaborative platforms across various levels
of management. Such platforms foster trust among companies, resulting in the
sharing of knowledge and expertise, which is critical for the dissemination of
green chemistry practices and the development of greener processes and products
at a lower cost. Collaboration platforms can be built in a variety of
dimensions including procurement, marketing, energy, water, waste disposal as
well as safety.
In
order to be more environmentally friendly, the Indian agrochemical business is
increasingly modifying its operations. Businesses have started putting
zero-emission solutions into practice, which has had a big positive impact.
Agrochemical companies can recover more than 80% of their water, reduce COD
levels by 40 times, and TDS levels by 60 times by implementing zero discharge
solutions, allowing them to comply with government regulations, save liability
costs, achieve uninterrupted production, and lower production costs (The Print,
2022).
2. Medium term approaches
Industries
should look for ways to change their chemistry in the medium term in order to maximize
the efficiency of their solvent consumption. This assists businesses in
reducing waste generation, improving material efficiency, and lowering costs.
Companies can also investigate new environmentally friendly aspects of
chemistry and chemical engineering, such as microwave chemistry.
Solvent
recovery:
Large amounts of organic solvents are used extensively in the chemical industry
in a variety of manufacturing steps. Except in a few cases, the solvents are
not involved in the reaction. At the end of the process, the solvents are
typically polluted and cannot be used again. As a result, it is customary to
discard them and swap them with fresh solvents. Solvent recovery is an
important tool for green and sustainable chemistry.
Alternate
Solvents:
Historically, solvents have been derived from crude oil, resulting in high
levels of toxic emissions in the atmosphere. The increased use of solvents,
combined with strict environmental regulations aimed at lowering VOC (Volatile
Organic Compounds), has resulted in the growth of bio solvents (greener
alternatives). Green solvents are classified according to product type as
soy methyl esters and lactate esters, derived from soybean oil, a biodegradable
alternative that can replace nearly 500 pounds of traditional chlorinated and
petroleum solvents. Toluene, NMP, acetone and xylene have been substituted by
ethyl lactate, another eco-friendly solvent. Greener alternatives are biodegradable,
recyclable, produce fewer harmful emissions and are non-corrosive.
Biocatalysts: Biocatalysis is
the term for the utilization of isolated enzymes or entire cells for synthetic
transformation. Enzymes are extremely effective catalysts that multiply reaction
rates by 100–1000 times. Because of the extreme selectivity of enzymes, they only
function on a single compound and produce a high yield of that particular
product. Compared to chemical catalysts, biocatalysts require a specific range
of temperature (20-40 oC) and pH (5-8). In addition to being more
effective (requiring lower concentrations), biocatalysts are also simple to
modify to improve selectivity, stability and activity. Biocatalysts have
historically been employed in the manufacturing of cheese and wine, but they
are currently being used more frequently in several other industries. Using
biocatalysts can help the industry increase yield and decrease waste in
addition to being eco-friendly and biodegradable (FICCI, 2014).
Microwave
chemistry:
Any material that has mobile electric charges, such as polar molecules in a
liquid or conducting ions in a solid, will be heated by microwaves because they
operate as high-frequency electric fields (Lucas, 2022). Polar molecules or
ions that oscillate as a result of an oscillating electric or magnetic field
are agitated in this process. The particles attempt to align themselves or be
in phase with the field when it is present as an oscillating field. However,
because of inter-particle friction and electrical resistance, the motion of
these particles is constrained, which causes them to move randomly and produce
heat. Different materials react to microwaves in different ways; some do so by
reflecting them, like copper; others do so by becoming translucent, like
sulphur; and yet others absorb them, like water. Microwave chemistry is used in
the production of drugs, agrochemicals, polymers, chemical synthesis and
extraction, the production of nanoparticles and drying processes.
Long Term Approaches
Industries
should put their long-term efforts into creating fresh green methods for
chemical production. This entails shifting away from reliance on fossil fuels
and toward renewable resources, as well as using biomass as a feedstock for the
development of bio-pesticides.
Bio-pesticides: These pesticides
offer an effective and environmentally friendly pest control method since they
are based on pathogenic microorganisms unique to a particular pest.
Bio-pesticides are living things that are pathogenic to the target pest, such
as bio-fungicides (Trichoderma), bio-herbicides (Phytophthora) and
bio-insecticides (Bacillus thuringiensis)
(Wickramaarachchi et al., 2017).
There are 700 products and 175 active bio-pesticide registered in the market
globally. Neem-based, Bacillus
thuringiensis, Trichoderma and NPV are a few of the primary bio-pesticides
made and used in India (FICCI, 2014).
Innovation in
product and process:
R&D spending by Indian businesses is now much lower than that of global
enterprises, at just 1% to 2% of their total sales. In order to apply green practices,
it is crucial that Indian enterprises invest in R&D activities. The
development of water-based formulations, target-specific chemical development
as opposed to generic chemical development, greener chemical synthesis methods,
fewer steps in product synthesis, lower dosage molecules leading to lower
volume implementation and fewer active ingredient emissions are some of the
focus areas.
Multi-disciplinary
approach:
Engineering, economics, sociology, toxicology and natural sciences are combined
in the multidisciplinary approach to create an ecosystem in which different
stakeholders (industries, governmental and educational institutions, NGOs and
society) work together to create a symbiotic system in which the entities
achieve material and energy efficiency and waste reduction by relying on
outputs and by-products produced by other ecosystem members. Businesses might
look into potential ways to turn trash from their processes into usable goods
that can be used in their own operations instead of relying on external sources
for raw materials. This ecosystem helps create a workable and sustainable
looping system by creating an entire chain of environmentally friendly chemical
processes across multiple industries. These approaches help to reduce the use
of energy and raw materials, the external reliance on feedstock and utilities and
the development of toxic waste, which saves money and the reputation of
agrochemical firms (FICCI, 2014).
References
FICCI
(2014). Knowledge
paper on safe and judicious use of agrochemicals and applications of green
chemistry. Available: https://ficci.in
Lucas
P. (2022). Molecules with and without polarity in microwave chemistry. Anal.
chem.: An Indian J. 22(2):1
Pereira J. (2020). Available: https://repositorio.ufscar.br/handle/ufscar/13749
The
print (2022). Gradual shift towards the implementation of green practices.
Available: https://theprint.in
Wickramaarachchi
W., Chaudhary M., Patil J. (2017). Facilitating microbial pesticide use in agriculture
in South Asia. SAARC Agriculture Centre,
Dhaka, Bangladesh, 226.
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