Researchers at the University of California, Riverside have developed a method to convert plastic waste into a highly porous form of charcoal or char. The char they created has a surface area of about 400 square meters per gram of mass. This char is able to capture carbon and could be used to improve soil water retention, soil aeration, and as a fertilizer.
To create the char, two common types of plastic waste – polystyrene or polyethylene terephthalate (PET) – were mixed with corn waste, which is made up of the stalks, leaves, husks, and cobs that remain in fields after harvesting. The resulting mix was then cooked with highly compressed hot water in a process called hydrothermal carbonization.
The team previously worked on an energy-efficient way to use corn waste alone to make activated charcoal used to filter pollutants from drinking water. That study showed that when the resulting char was activated with potassium hydroxide it was able to absorb 98% of the pollutant vanillin from test water samples. Unfortunately, the char composed of plastic and corn waste absorbed only about 45% of vanillin in test water samples – making it ineffective for water cleanups.
“It could be a very useful biochar because it is a very high surface area material,” Kandis Leslie Abdul-Aziz, a UCR assistant professor of chemical and environmental engineering, said. “So, if we just stop at the char and not turn that it activated carbon, I think there are a lot of useful ways that we can utilize it.”