Efficient Depolymerization of Polystyrene with Table Salt and Oxidized Copper

The global production of polystyrene (PS) has exceeded 15 million metric tons in 2019 because of its widespread use in packaging and nonpackaging sectors. Therefore, the development of efficient and low-cost recycling strategies for PS is highly desirable. Herein, we present a PS-depolymerization approach that can be performed in the presence of table salt and an oxidized copper scrubber. The obtained liquid portion has styrene content >83%. For the control sample (without NaCl or metal oxides), the styrene content was 66%. In addition, PS depolymerization in the presence of oxidized copper produced the styrene monomer in an 84% yield. The recovered styrene monomer was repolymerized without further purification, and the thermal properties of the obtained PS were evaluated. This work has the potential to facilitate the chemical recycling of waste PS that is produced at a scale of 15 million tons/year using environmentally friendly catalysts and energy-efficient process; therefore, this study enables multiple green chemistry principles such as waste prevention, energy-efficient processes, and environmentally friendly catalysts.