Bath process produces safer microbeads

CHEMICAL engineers at the UK’s University of Bath have developed a continuous process to make biodegradable microbeads and will now work with industry to see them used in cosmetics.

Mircobeads have a bad reputation, with the UK government planning to ban their use in cosmetics and care products later this year. The tiny spheres of plastic are used as exfoliants but are so small that they slip through wastewater treatment processes and into the environment where they kill fish and concentrate toxins within the food chain.

Bath researchers can now create a biodegradable alternative from cellulose. The manufacturing process involves pushing a solution of cellulose through a tubular membrane into a channel of flowing sunflower oil.

“Droplets form on the surface of the membrane and as the sunflower oil flows through the centre, it cleaves off these droplets, forming droplets within the sunflower oil phase,” says chemistry researcher James Coombs OBrien.

The beads are robust enough to remain stable in a bodywash but can be broken down by organisms in wastewater treatment plants or biodegrade in the environment.

Janet Scott, reader in the chemistry department and a member of Bath’s Centre for Sustainable Chemical Technologies (CSCT), added: “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.”

The team says the cellulose could be sourced from waste streams in the paper-making industry.

Davide Mattia, professor of chemical engineering at Bath and part of the CSCT, said: “Our goal was to develop a continuous process that could be scaled for manufacturing. We achieved this by working together from the start, integrating process design and chemistry optimisation, showing the strength of the multidisciplinary approach we have in the CSCT.”

Scott added: “We hope in the future these could be used as a direct replacement for plastic microbeads.”

The team will now work with industry to develop the microbeads for commercial use. The team has been awarded £1m (US$1.27m) by the EPSRC to develop porous microbeads that could be impregnated with agrochemicals for use in, for example, slow release fertilisers.