Green Chemistry and its role in a sustainable world
- Part 2 -

Dr Arati Ningombam,, Dr Romila Akoijam, Dr Laishram Kanta Singh, Dr Ch Basudha Devi, Dr Ch Sonia, Dr Ch Premabati *

Nanoplastics are particles unintentionally produced (ie from the degradation and the manufacturing of plastic objects) and presenting a colloidal behaviour within the size range from 1 to 1000 nin; microplastics are less than 5 mm. Italian scientists Errico, Fattorusso and their team first studied the interactions between polystyrene nanoplastics and human ubiquitin at an atomic level.

They have found that polystyrene nanoplastics interact with human ubiquitin, a regulatory protein found in most tissues. Their study showed that nanoplastics change the structure of ubiquitin and disrupt cell ubiquitination processes, which could have implications for human health afterall ubiquitin is a small protein with 76 amino acid residues.

A process called ubiquitination sees ubiquitin added to other proteins where it acts as a tag, marking them for a variety of cellular signalling and proteasomal degradation pathways. Green Chemistry involves the invention, design and application of chemical products and processes to reduce or eliminate the use and generation of hazardous substances in any form.

Green chemistry is how we can develop chemical processes and earth-friendly products that will prevent pollution in the first place. Through green chemistry, alternatives to hazardous substances can be created.

Chemical processes can be designed to reduce waste and demand on diminishing resources. Processes can be employed that use smaller amounts of energy that can be diverted to other worth-while activities. All this can be done, and economic growth and opportunities can still be maintained while providing affordable products and services to a growing world population, albeit more sustainably.

The following list outlines a framework for making a greener chemical, process, or product. Paul Anastas and John Warner developed it in 1998. Green Chemistry is based on these twelve principles:

1. Prevention : It is better to prevent waste than to treat or clean up waste after it has been created.

2. Atom Economy : Synthetic methods should be designed to maximise the incorporation of all materials used in the process into the fmal product.

3. Less Hazardous Chemical Syntheses: Wherever practicable, synthetic methods should be designed to use and generate substances with little or no toxicity to human health and the environment.

4. Designing Safer Chemicals : Chemical products should be designed to preserve the efficacy of function while reducing toxicity.

5. Safer Solvents and Auxiliaries : The use of auxiliary substances (e.g., solvents, separation agents, etc.) should be made unnecessary wherever possible and innocuous when used.

6. Design for Energy Efficiency: Energy requirements should be recognised for their environmental and economic impacts to be minimised. Synthetic methods should be conducted at ambient temperature and pressure.

7. Use of Renewable Feedstocks: A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable.

8. Reduce Derivatives: Unnecessary derivatisation (use of blocking groups, protection/deprotection, temporary modification of physical/chemical processes) should be minimised or avoided if possible because such steps require additional reagents and can generate waste.

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

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

11. Real-time analysis for Pollution Prevention: Analytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to forming hazardous substances.

12. Inherently Safer Chemistry for Accident Prevention: Substances and the form of a substance used in a chemical process should be chosen to minimise the potential for chemical accidents, including releases, explosions, and fires.

Govts and scientific communities worldwide acknowledge that using green chemistry and engineering techniques results in a cleaner, more sustainable planet and has numerous sound societal effects. These advantages persuade organisations and authorities to support the creation of sustainable goods and procedures. Today we face multiple threats and challenges as individuals and as a species.

Climate change implications, food and nutritional crises, and the lingering coronavirus pandemic are the most severe and immediatein recent times. One such crisis facing our planet in the 1980s that alarmed scientists and scared the general public was the depletion of the ozone layer. The ozone hole was detected(above Antarctica) for the first time in December 1984 by satellites in NASA's Nimbus Program, Nimbus-7, to be exact.

People only had to look at a picture to see atmospheric chemistry physically. Policymakers were convinced to take action immediately. The discovery ultimately led to the 1987 Montreal Protocol. The Montreal Protocol on Substances that Deplete the Ozone Layer is the land-mark multilateral environmental agreement that regulates the production and consumption of nearly 100 man-made chemicals referred to as ozone-depleting substances (ODS).

When released into the atmosphere, those chemicals damage the stratospheric ozone layer, Earth's protective shield that protects humans and the environment from harmful levels of ultraviolet radiation from the sun. The Protocol is, to date, one of the rare treaties to achieve universal ratification.

The 1985 Vienna Convention for the Protection of the Ozone Layer and its 1987 Montreal Protocol on Substances that Deplete the Ozone Layer was established to protect human health and the environment from the threat of ozone depletion, as exemplified by the ozone hole. Both have achieved universal ratification with 198 Parties. The Vienna Convention calls on Parties to cooperate on scientific research and observations.

The Montreal Protocol controls nearly 100 manufactured ozone-depleting substances (ODS), most of which are also potent greenhouse gases. It also now controls 18 hydro-fluoro-carbons (HFCs), potent greenhouse gases that do not destroy ozone. Implementation of the Montreal Protocol has led to the global phase-out of 98.6 per cent of ODS, or 1.75 million Ozone Depletion Potential (ODP) tonnes. The remaining 1.4 per cent is mainly hydrochloro-fluoro-carbons (HCFCs).

The latest NASA Ozone Watch datafor 2022 shows that the hole steadily shrinks yearly and is no longer a threat. The adoption of the Montreal Protocol on Substances that Deplete the Ozone Layer on September 16, 1987, marked a turning point in environmental history. It is considered to be an "unparalleled environmental success story".

The Montreal Protocol is a classic rolemodel of science and political willpower joining forces, and the results change the world positively. Such a coming together of will and determination is again needed from Govts, industry and the general public to change our planet's current trajectory for a viable, thriving, life-sustaining future.

Claiming the Earth and its resources from pollution will take time, effort and will, and Green Chemistry is one of the many paths we have to take to achieve it.

Concluded...