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Research into biodegradable polymers helps fight plastic pollution

02 September 2024 | Story André Damons | Photo Supplied

Dr Puseletso Mofokeng — Dr Julia Puseletso Mofokeng, from the UFS’s Department of Chemistry, is doing research into biodegradable polymers for application in disposable product packaging.

A researcher from the University of the Free State (UFS) is contributing to the fight against plastic pollution through her research into biodegradable polymers – large, chain-like molecules – as a more environmentally friendly alternative to petroleum-based plastics.

Plastic pollution is a global environmental problem, with 19 to 23 million tonnes of plastic waste leaked into aquatic ecosystems every year.

Dr Julia Puseletso Mofokeng, Senior Lecturer and Researcher in the UFS Department of Chemistry, hopes her research into how biodegradable polymers can be used in disposable product packaging can influence the industry and policymakers to enforce the use of biopolymers or biodegradable polymers in disposable products. This would help reduce plastic waste and boost environment-conservation efforts.

The United Nations Environment Programme (UNEP) describes plastic waste as a serious environmental problem – humans produce about 400 million tonnes of plastic waste every year. Approximately 36% of all plastics produced are used in packaging, including single-use plastic products for food and beverage containers, approximately 85% of which ends up in landfills or as unregulated waste.

Researching biodegradable polymers

Dr Mofokeng’s desire to solve the waste problem in her community of Bophelong village in Qwaqwa, Free State – where community members dumped and burned all sorts of waste, including plastics – inspired her towards her field of research.

Today, her research is aimed at managing plastic waste to combat environmental and atmospheric pollution (from incineration), conserve energy, and improve water quality, including ensuring safe drinking water.

High levels of plastic waste have led to increased research into and development of biodegradable polymers as an alternative to non-biodegradable materials for short-shelf-life goods (such as packaging for fresh fruit and vegetables).

Biopolymers or biodegradable polymers, explains Dr Mofokeng, are derived from renewable resources including, but not limited to, vegetable oils, starches and animal fats. They can therefore be easily disposed of after use without harming the environment.

“My research is based on the preparation and characterisation of completely biodegradable polymers, their blends, and composites or nanocomposites filled with unmodified or modified inorganic fillers, natural fibres, as well as synthesised carbonaceous materials,” she says.

Such materials are developed for various applications, including packaging, electromagnetic interference shielding (blocking unwanted signals), and the removal of heavy metals and other contaminants from water bodies.

“To achieve these aims, I and my small research group are preparing completely biodegradable polymer blends.”

This involves adjusting their morphology (structure) and some of their properties (thermal, thermomechanical, mechanical, and flame retardancy) to match those of petroleum-based polymers in their replacement for disposable products; by reinforcing with natural fibres, and minerals.

Biodegradable polymers can degrade within a few days to a few years depending on their source, type, and biodegradation method used, while petroleum-based polymers can exist for hundreds to thousands of years without degrading. Moreover, because biodegradable polymers are produced from natural resources, their biodegradation mainly produces carbon dioxide, water, and other non-toxic byproducts, Dr Mofokeng adds.

“Biodegradable polymers can degrade by themselves under natural environmental conditions – in one to three years – or may require human intervention to degrade where composts are prepared or conditions are controlled in order to degrade the polymers. The latter two being the fastest, where it could take days to months. In my previous research project [we] kept polylactic acid filled with short sisal fibre in plain water at 80℃, and all the tested samples degraded within 10 days.”

She and a PhD student are conducting an ongoing experiment involving three different biodegradable polymer systems exposed to different conditions outside and under soil, measuring the rate of biodegradation by mimicking the environmental conditions found in dumping sites and landfills.

Signs of biodegradation on the samples showed clearly after 14 months, with cracks, surface erosion, and a decrease in the initial weighed mass, suggesting that the polymers could be completely degraded within two to three years.

Closer to goal

Dr Mofokeng, who has been a National Research Foundation (NRF) Y2-rated researcher since 2021, says since most food outlets and restaurants in South Africa have already started using paper- and bio-based polymer materials in cutlery, straws, and takeaway packaging, the country seems to be closer to its goal of using biodegradable polymers for disposable packaging.

The UFS, too, is aiming to phase out the use of plastic bottles in the next three to five years. This will be done by installing filtered water machines in all its buildings.

“We are now left with policymakers to enforce strict laws governing production; and retail industries to use biopolymers or biodegradable polymers in disposable packaging materials,” she says.

New research

Dr Mofokeng and her group’s research is in line with the United Nations’ Sustainable Development Goals (SDGs), including ensuring good health and wellbeing (SDG3), providing clean water and sanitation (SDG6), forging sustainable cities and communities (SDG11), establishing sustainable consumption and production patterns (SDG12), and protecting life below water (SDG14).

She has been researching polymers for almost two decades, and remains passionate about her research field and educating communities. Her new research project, in collaboration with colleagues from her department, targets the removal of heavy metals and other contaminants from groundwater. Testing and water treatment is set to take place in different regions in Qwaqwa, specifically among households that collect drinking and cooking water from boreholes.

Dr Mofokeng’s research group was established in 2016 with one honours and two master’s students. She has since supervised nine honours, seven master’s and one PhD student.

She also recently established international research collaborations with the Libyan Advanced Center for Chemical Analysis and the Faculty of Technology at the University of Banja Luka in Serbia.

News Archive

Research into surrogate milk important to wildlife conservation

2017-05-08

Prof Gary Osthoff from the UFS Department of
Microbial, Biochemical and Food Biotechnology,
will soon work on a milk formula for elephants.
Photo: Supplied

Research is being done at the University of the Free State (UFS) to analyse and synthetically imitate the unique milk of various wildlife species. This research is not only of scientific value, but also serves the conservation of South Africa’s wildlife species. At the forefront of this research is Prof Garry Osthoff from the Department of Microbial, Biochemical and Food Biotechnology.

Orphaned rhino calf pulled through with surrogate milk
“There is still a lot of research to be done. Naturally the research is of scientific importance, but with surrogate milk having the same composition as the mother’s milk of a specific species, orphaned calves or cubs of that species could be pulled through during a difficult time of weaning. Bearing in mind that exotic animals fetch thousands and even millions of rands at auctions, it goes without saying a game farmer will do everything possible to provide only the best nourishment to such an orphaned animal. In such a case, synthetically-manufactured milk would be the right choice,” says Prof Osthoff.

The fruits of his research were recently demonstrated in Germany when a rhino calf was left orphaned in the Leipzig Zoo. Prof Osthoff’s article: “Milk composition of a free-ranging white rhinoceros during late lactation” was used as a directive for applying surrogate milk for horse foals (which is already commercially available), since the composition of horse and rhino milk largely corresponds. The surrogate milk was used with great success and the rhino calf is flourishing. He mentions that such an orphan is often given the wrong nourishment with the best intentions, resulting in the starvation of the animal despite the amount of cow’s milk it devours.

With surrogate milk having the same
composition as the mother’s milk of a
specific species, orphaned calves or
cubs of that species could be pulled
through during the difficult time
of weaning.

Milk formula for baby elephants in the pipeline
With baby elephants left orphaned due to the increase in elephant poaching for their ivory, several attempts have been made to create a milk formula in order to feed these elephants. To date, many elephants have died in captivity from side effects such as diarrhoea as a result of the surrogate formula which they were fed.

Prof Osthoff recently received a consignment of frozen milk which he, together with researchers from Zimbabwe, will use to work on a milk formula for elephants. They are studying the milk in a full lactation period of two years. During lactation, the composition of the milk changes to such an extent that a single surrogate formula will not be sufficient. Four different formulas should probably be designed.

Prof Osthoff says that of the different species he has researched, elephants are the most interesting and deviate most from the known species.

Although his research to develop surrogate milk is adding much value to the wildlife industry, and although he finds this part of his work very exciting, his research focus is on food science and nutrition. “What is currently authentic in milk research is the study of the fat globules with content, the structure and composition of the casein micelle, and the prebiotic sugars. The knowledge which is gained helps to improve the processing, development of new food products, and development of food products for health purposes,” says Prof Osthoff.

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