Biodegradable microbeads could replace harmful plastics found in cosmetics

Scientists have developed biodegradable cellulose microbeads that could replace harmful tiny pieces of plastic that pollute the ocean.

Microbeads, tiny spheres of plastic less than 0.5mm in size, are added to products such as face wash, sunscreen and toothpaste to give them a smooth texture.

Experts warn they are too small to be removed by sewage filtration systems and 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. About eight million tonnes of plastic enters the ocean each year.

The Government plans to ban microbeads this year, following campaigning by environmental groups such as Greenpeace.

Engineers from the University of Bath's Centre for Sustainable Chemical Technologies have developed a biodegradable, renewable alternative to plastic microbeads.

Dr Janet Scott, reader in the Department of Chemistry at the university, 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."

Cellulose is the material that forms the tough fibres found in wood and plants.

The beads are made using a solution of cellulose, which is forced through tiny holes in a tubular membrane.

This creates 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.

Scientists can alter the physical properties of the beads by changing the structure of the cellulose, for example to make the beads harder.

These microbeads are robust enough to remain stable in a body wash, but can be broken down by organisms at the sewage treatment works, or in the environment over a short period of time.

Researchers believe that they could use cellulose from a range of waste sources, such as from the paper-making industry, as a renewable source of raw material.

Their work has been published in the journal ACS Sustainable Chemistry and Engineering.