The very word “chemical” has become associated with toxicity, but, as chemist Dr Rosa Klein reminds us, the reality is not so black-and-white:
“Water is a chemical! And we've been doing chemistry for hundreds of years – when the Voortrekkers made soap from animal fat – that was chemistry too.”
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Klein reminds us that modern society at large also needs to take responsibility for potential toxins entering the environment: anyone who uses chemical products, from soap to petroleum to pharmaceuticals, is creating demand for them.
Klein, a senior lecturer in the Department of Chemistry, Rhodes University, and chairperson of the Green Chemistry Division Committee of the South African Chemistry Institute (SACI), is on a mission not only to “green” her field, but to improve public perception of chemists and what they do.
The creation of the Green Chemistry Division, and the fact that Durban hosted the fifth International Green Chemistry Conference this year are indications that South Africa is in the process of joining a growing global movement among chemists to take better care of how their work affects the environment.
Green design 'from cradle to grave'
Green chemistry, says Klein, means analysing the entire life cycle of a product, from raw materials to waste products (a holistic approach known as “cradle to grave”), and designing this better so that the impact on health and the environment is reduced all along the way.
“We want to pre-empt undesirable consequences, not deal with them as an afterthought,” says Klein.
Harmful consequences arose in the past through chemists solving one problem (like putting lead in petrol to reduce engine knocking), but creating another (lead in petrol fumes is toxic, especially to developing children).
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“There are minimum health and safety standards chemists must comply with, but green chemistry goes beyond that,” says Prof Rui Krause, Professor of Chemistry at Rhodes University and also on SACI's Green Chemistry Committee.
“When it comes to greening the production process, the low-hanging fruit are renewable resources and waste – using more renewables instead of fossil fuels as the starting point for a product, and ending up with fewer, and less harmful, waste products.”
A strong trend in green chemistry is to combine these two aspects – to use waste from one process as the starting material or “feedstock” for another.
Kelin and Krause name several exciting examples of how this is being done.
Instead of discarding corn husks, chemists are converting them to PLA (polylactic acid), a biodegradable, recyclable bioplastic. Among its many uses, PLA is used for safe medical implants; when it biodegrades, it forms lactic acid that occurs naturally in the body. Bioplastics are an improvement on common plastics derived from non-renewable petroleum, a process which also emits more greenhouse gases.
One of the recipients of this year's Presidential Green Chemistry Challenge Award was Solazyme, a company that ferments microalgae to produce sustainable oils, which can replace petroleum as building blocks for many industrial chemicals.
Another winner, the Solberg Company, have created a fire-fighting foam that replaces fluorinated surfactants, which are toxic and persistent chemicals in the environment, with surfactants and sugars that have far less of an impact.
Other examples come from corporates, which are increasingly realising that green chemistry can mean financial rewards down the line.
Eighty percent of General Motors' manufacturing plants, for example, are moving towards zero landfill for their waste products. One of their innovations has been to use scrap battery covers as bird nesting boxes, instead of sending them to landfill.
Pharmaceutical giant Boots has improved its production of the pain-killer ibuprofen; previously, 1kg of feedstock produced 1.5kg waste. By improving their production process, including recycling one of the byproducts – acetic acid, or vinegar – waste is now minimal.
According to the Environmental Protection Adency (EPA) incorporating green chemistry into production processes eliminates over 826 million pounds of hazardous chemicals per year, as well as 7.8 billion pounds of carbon emissions, equivalent to taking 810 000 automobiles off the road.
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