Scientists and engineers at the University of Bath have developed biodegradable cellulose microbeads which could replace the ones undoubtedly lurking in your bathroom cabinet. The 0.5mm spheres of plastic pollute the environment because once they are rinsed off after use, they become a permanent part of the natural cycle: plankton in the rivers and seas swallow these microscopic plastic particles and introduce them into the food chain. They are too small to be removed by sewage filtration systems and so end up in rivers and oceans, where they are ingested by birds, fish and other marine life. It is estimated that a single shower can result in 100,000 plastic particles entering the ocean, contributing to the eight million tonnes of plastic that enters the ocean every year.
“We’ve developed a way of making microbeads from cellulose, which is not only from a renewable source, but also biodegrades into harmless sugars."
The beads are made from cellulose, which is the material that forms the tough fibres found in wood and plants. In this process our scientists dissolve the cellulose to reform it into tiny beads by forming droplets that are then “set”.
These microbeads are robust enough to remain stable in a bodywash, but can be broken down by organisms at the sewage treatment works, or even in the environment in a short period of time.
The researchers anticipate they could use cellulose from a range of “waste” sources, including from the paper making industry as a renewable source of raw material.
Dr Janet Scott, Reader in the Department of Chemistry and part of the CSCT, said: “Microbeads used in the cosmetics industry are often made of polyethylene or polypropylene, which are cheap and easy to make. However these polymers are derived from oil and they take hundreds of years to break down in the environment.
“We’ve developed a way of making microbeads from cellulose, which is not only from a renewable source, but also biodegrades into harmless sugars. We hope in the future these could be used as a direct replacement for plastic microbeads.”
The beads are made using a solution of cellulose which is forced through tiny holes in a tubular membrane, creating spherical droplets of the solution which are washed away from the membrane using vegetable oil. The beads are then collected, set and separated from the oil before use.
They will work with industrial partners, to develop materials that could be used in cosmetics and personal care products, or impregnated with agrichemicals for use in, for example, slow release fertilisers.
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