Agricultural plastic mulch helps farmers conserve water, control weeds, and improve crop productivity, but disposing of the used films creates a growing environmental challenge. Researchers have now developed a catalyst made from fishbone-derived char, phosphoric acid, and iron that converts low-density polyethylene agricultural film into bio-oil with a yield of up to 89.32 wt.% and an olefin selectivity of 84.03%.
The study, published in Sustainable Carbon Materials, explores a microwave-assisted catalytic pyrolysis process designed to recover valuable hydrocarbons from waste agricultural plastics while also finding a productive use for discarded fish bones.
"Our goal was to develop a low-cost catalyst that can direct plastic pyrolysis toward more valuable products rather than simply breaking the polymer into a complex mixture of hydrocarbons," said a study author. "By combining the natural mineral structure of fish bones with phosphorus and iron, we were able to create complementary acid and metal active sites that strongly favored the formation of olefins."
Low-density polyethylene, or LDPE, is widely used for agricultural mulch because it is lightweight, durable, and effective at retaining soil moisture. After use, however, contaminated films can be difficult to collect and recycle. Landfilling or incineration can waste their carbon resources and may create additional environmental burdens.
Pyrolysis offers another route by heating plastics without oxygen and breaking their long molecular chains into smaller hydrocarbons. A major challenge is controlling what those reactions produce.
