Quirks & Quarks

Making the most of fish waste: how scientists transformed it into biodegradable plastic

Plentiful oil in the fish tissues is the basis of this new material.

Plentiful oil in the fish tissues is the basis of this new material.

A new study suggests that the parts of this fish that will not be eaten could be turned into plastic. (Patrick Morrell/CBC)

A scientist at Memorial University of Newfoundland in St. John's has developed a process for making polyurethane plastic from fish waste, like heads, guts and skin.

Francesca Kerton, from the university's Department of Chemistry described a process for making this environmentally friendly alternative to petroleum-based plastic in a new study.

Polyurethane is one of the most widely used plastics because of its durability and other valuable properties. 

Floating the idea

Kerton came up with the idea to make plastic from fish waste after being told about the struggles salmon farmers were having in disposing of unwanted fish waste. She was aware that bioplastics had been developed from plant and vegetable oil, and though the oil-rich fish tissue might have similar potential. 

Polyurethane made from fish-waste is transparent like cling-wrap, and red in colour (Courtney Laprise)

Add fish-waste and stir

The process begins with what Kerton called a "fish smoothie." Heads, bones and skin were placed in a food processor, and the fish oil came to the surface of the resulting liquid. Next, oxygen was infused into the oil to form molecules called epoxides. Carbon dioxide and amino acids were also added to the mix.

The result was a polyurethane polymer in the form of a thin film-like material that resembles plastic cling wrap. The process eliminates the fish smell, but results in the film having an orange-red hue. 

Mikhailey Wheeler from MUN's Chemistry Department, holds up a piece of the polyurethane made from fish-waste (Submitted by Mikhailey Wheeler)

Kerton was pleased to discover the material seems to be biodegradeable.  With the addition of an enzyme, fungi and bacteria, started to form on the surface after a few weeks, which would eventually break down the material.

 

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