Scientists discover how to extract clean hydrogen fuel from dirty mixed plastic

Modern life is hard to imagine without plastic materials, which accompany us at every step, from packaging to car parts. But when these objects have served their purpose, they become extremely persistent waste. Traditional recycling requires time-consuming, expensive and labor-intensive sorting by material type, which means that the vast majority of plastics end up in landfills or incinerators, where they cause greenhouse gas emissions.

A research team led by UCLA Samueli School of Engineering and Ewha University in South Korea has presented an innovative chemical solution. They have developed a process that directly converts a mixture of three of the most common types of plastic into hydrogen fuel with an extremely high purity of more than 90 percent in a single “reactor.” The process occurs at significantly lower temperatures than conventional gasification methods, and the carbon dioxide is trapped in a solid mineral form instead of being released into the atmosphere.

The technology is based on alkaline thermal treatment, in which sodium hydroxide reacts with organic material under the influence of heat. Scientists originally developed this method to convert biomass such as seaweed into hydrogen. However, when applied to plastics, they encountered a challenge: while polyethylene terephthalate (PET) reacted perfectly and at significantly lower temperatures (300 to 400 degrees Celsius lower than in conventional steam gasification), polyethylene (PE) and polypropylene (PP) were initially chemically passive.

To activate these two hard materials, the researchers introduced a preliminary thermal oxidation. The plastic is briefly exposed to mild heat in air, which incorporates oxygen groups into the polymer chains and allows the alkaline process to work. The carbon released during the final reaction is bound to sodium carbonate, which can be easily processed into calcium carbonate – a stable mineral widely used in industry. Less than 13 percent of the carbon remains in gaseous form, and direct emissions to the environment are negligible.

Although this is a remarkable breakthrough that solves the problems of high sorting costs and offers a solution for the energy transition, it is important to remain realistic. The technology will need to be further optimized before being implemented in practice and its actual economic viability at the industrial scale will need to be assessed in detail.