Cheaper green plastics from cooking oil

Waste oil from cooking fish and chips and other fried food could be used to create environmentally friendly plastic more cheaply, according to researchers at the University of Wolverhampton.

The new research suggests using waste cooking oil as a starting material in the creation of environmentally friendly plastics, or bioplastics, could reduce the cost of production.

It has a double benefit for the environment as it also reduces environmental contamination caused by the disposal of waste oil.

The resulting high quality plastic is suitable for use in medical implants and cancer therapy treatments, according to the Wolverhampton scientists who presented their work at the Society for General Microbiology’s Autumn Conference at the University of Warwick.

A major problem of environmental pollution is that plastics produced by the petrochemical industry are not biodegradable and therefore accumulate in the environment at a rate of more than 25 million tonnes per year.

Bioplastics are more sustainable because they can break down in the environment faster than fossil-fuel plastics, which can take more than 100 years.

The Poly(hydroxyalkanoate) (PHA) family of polyesters is synthesised by a wide variety of bacteria. The resulting biopolymer is biodegradable and non-toxic. These bacterial PHA biopolymers have attracted much attention as environmentally friendly bioplastics for a wide range of agricultural, marine, and medical applications. Poly 3-hydroxybutyrate (PHB) is the most commonly produced polymer in the PHA family.

Currently, growing bacteria in large fermenters to produce high quantities of this bioplastic is expensive because glucose is used as a starting material.

Work by a research team from the School of Applied Sciences at the University of Wolverhampton suggests that using waste cooking oil as a starting material reduces production costs of the plastic.

Victor Irorere, who carried out the research, said: “Our bioplastic-producing bacterium, Ralstonia eutropha H16, grew much better in oil over 48 hours and consequently produced three times more PHB than when it was grown in glucose.

“Electrospinning experiments, performed in collaboration with researchers from the University of Birmingham, showed that nanofibres of the plastic produced from oils were also less crystalline, which means the plastic is more suited to medical applications.”

Previous research has shown that PHB is an attractive polymer for use as a microcapsule for effective drug delivery in cancer therapy and also as medical implants, due to its biodegradability and non-toxic properties. Improved quality of PHB combined with low production costs would enable it to be used more widely.

The disposal of used plastics - which are largely non-biodegradable - is a major environmental issue.

Plastic waste on UK beaches has been steadily increasing over the past two decades and now accounts for about 60% of marine debris.

Dr Iza Radecka from the University of Wolverhampton is leading the research. She said: “The use of biodegradable plastics such as PHB is encouraged to help reduce environmental contamination. Unfortunately the cost of glucose as a starting material has seriously hampered the commercialisation of bioplastics.

“Using waste cooking oil is a double benefit for the environment as it enables the production of bioplastics but also reduces environmental contamination caused by disposal of waste oil.”

The next challenge for the group is to do appropriate scale-up experiments, to enable the manufacture of bioplastics on an industrial level.

ENDS

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