Collaboration between EdUHK and CityU
Currently, waste plastic accounts for as much as 20% of Hong Kong's solid waste. Associate Professor Chau Cheuk-fai of the Department of Science and Environmental Studies at the Education University of Hong Kong, who is engaged in chemical research, began research on plastic degradation technology with scholars from the City University of Hong Kong last year.
Chau said: "Plastic is a polymer that does not easily deform when heated and pressurized, but this also makes plastic difficult to decompose."
He emphasized that degrading plastic is not a new thing, and traditional methods have always used pyrolysis for plastic treatment. However, the traditional method takes one to two hours and requires high energy to pressurize the plastic, which ultimately reduces the recycling value of the plastic.
Foam plastic lunch boxes pose no problem
Chau Cheuk-fai stated that collected plastic is first ground into small plastic particles by machine. "In the water, we add the catalyst we developed and hydrogen peroxide. If there is sunlight, it will degrade into carbon dioxide; even without sunlight, there is energy in the air at room temperature, and the plastic will turn into organic fuel."
Compared with traditional pyrolysis, the new technology reduces the degradation time from one to two hours to an average of ten minutes, and even foam plastic lunch boxes, which are considered very difficult to degrade, can be reduced to five minutes. Chau pointed out: "For every ton of plastic, pyrolysis costs HK$1,330 in electricity. Since the new technology does not require high temperatures and pressures, it saves 95% in energy costs, and the pricing of the catalyst is also controlled at a level suitable for popularization."
Catalyst degrades 90% of plastic types
When asked whether the water after degradation would become sewage, Chau Cheuk-fai stated that after the plastic degrades into carbon dioxide, the water will return to being ordinary water and will not affect the environment. "Even if it turns back into organic fuel, you just need to separate the oil from the water."
Since plastic is generally divided into seven major categories, he admitted that in the initial stage of research, he was worried that different plastics would require different catalysts. However, so far, it has been found that a single catalyst can achieve the effect of degrading 90% of plastic types. "The next step is to cooperate with mechanical engineers and biological engineers to conduct larger-scale field tests and apply it at the industrial level within three to five years."
He hopes that through the research results, the next generation can be educated about the concepts of plastic classification and recycling, long-term making Hong Kong a "plastic-free city."
