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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

Bloemfontein's quality of tap water compares very favourably with bottled water

2009-08-04

The quality of the drinking water of five suburbs in Bloemfontein is at least as good as or better than bottled water. This is the result of a standard and chemical bacterial analysis done by the University of the Free State’s (UFS) Centre for Environmental Management in collaboration with the Institute for Groundwater Studies (IGS).

Five samples were taken from tap water sources in the suburbs of Universitas, Brandwag, Bain’s Vlei, Langenhoven Park and Bayswater and 15 samples were taken of different brands of still and unflavoured bottled water. The samples were analysed at the laboratory of the IGS, while the interpretation of the analysis was done by the Centre for Environmental Management.

“We wanted to evaluate the difference in quality for human consumption between tap water and that of the different brands of bottled water,” said Prof. Maitland Seaman, Head of the Centre for Environmental Management.

“With the exception of two samples produced by multinational companies at their plants in South Africa, the different brands of bottled water used for the study were produced by South African companies, including a local small-scale Bloemfontein producer,” said Prof. Seaman.

According to the labels, the sources of the water vary from pure spring water, to partial reverse osmosis (as an aid to standardise salt, i.e. mineral, content), to only reverse osmosis (to remove salts). (Reverse osmosis is a process in which water is forced under pressure through a pipe with minute pores through which water passes but no – or very low concentrations of – salts pass.)

According to Prof. Seaman, the analysis revealed some interesting findings, such as:

• It is generally accepted that drinking water should have an acceptable level of salt content, as the body needs salts. Most mineral contents were relatively higher in the tap water samples than the bottled water samples and were very much within the acceptable range of drinkable water quality. One of the bottled samples, however, had a very low mineral content, as the water was produced by reverse osmosis, as stated on the bottle. While reverse osmosis is used by various producers, most producers use it as an aid, not as a single method to remove nearly all the salts. Drinking only such water over a prolonged period may probably have a negative effect on the human physiology.

• The pH values of the tap water samples (8,12–8,40) were found to be slightly higher (slightly alkaline), like in all south-eastern Free State rivers (from where the water is sourced) than the pH of most of the bottled water samples, most of which are sourced and/or treated in other areas. Two brands of bottled water were found to have relatively low pH levels (both 4,5, i.e. acidic) as indicated on their bottles and as confirmed by the IGS analysis. The health implication of this range of pH is not significant.

• The analysis showed differences in the mineral content given on the labels of most of the water bottles compared to that found by IGS analysis. The possibility of seasonal fluctuation in content, depending on various factors, is expected and most of the bottling companies also indicate this on their labels. What was a rather interesting finding was that two pairs of bottled water brands claimed exactly the same mineral content but appeared under different brand names and were also priced differently. In each case, one of the pair was a well-known house brand, and the other obviously the original producer. In one of these paired cases, the house brand stated that the water was spring water, while the other (identical) “original” brand stated that it was spring water treated by reverse osmosis and oxygen-enriched.

• Nitrate (NO3) levels were uniformly low except in one bottled sample, suggesting a low (non-threatening) level of organic pollution in the source water. Otherwise, none of the water showed any sign of pollution.

• The bacterial analysis confirmed the absence of any traces of coliforms or E.coli in any of the samples, as was also indicated by the bottling companies. This is very reassuring. What is not known is how all these waters were sterilised, which could be anything from irradiation to chlorine or ozone treatment.

• The price of the different brands of bottled water, each containing 500 ml of still water, ranged between R3,99 and R8,99, with R5,03 being the average price. A comparison between the least expensive and the most expensive bottles of water indicated no significant difference in quality. In fact, discrepancies were observed in the most expensive bottle in that the amount of Calcium (Ca) claimed to be present in it was found to be significantly different from what the analysis indicated (29,6 mg/l versus 0,92 mg/l). The alkalinity (CaCO3 mg/l) indicated on the bottle was also found to differ considerably (83 mg/l versus 9,4 mg/l). The concentration of Total Dissolved Salts (TDS) was not given on the product.

“The preference for bottled water as compared to Bloemfontein’s tap water from a qualitative perspective as well as the price discrepancy is unjustifiable. The environmental footprint of bottled water is also large. Sourcing, treating, bottling, packaging and transporting, to mention but a few of the steps involved in the processing of bottled water, entail a huge carbon footprint, as well as a large water footprint, because it also requires water for treating and rinsing to process bottled water,” said Prof. Seaman.

Media Release
Lacea Loader
Deputy Director: Media Liaison
Tel: 051 401 2584
Cell: 083 645 2454
E-mail: loaderl.stg@ufs.ac.za
3 August 2009

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