Circular economy in polystyrene photodegradation to valuable chemicals.

The swift buildup of plastic debris has led to worldwide environmental contamination and resource depletion. Transforming plastic waste into beneficial chemicals and fuels has been considered as an effective approach to reduce plastic waste and encourage a circular economy. This review critically discusses the various types of methods of polystyrene (PS) recycling, like mechanical recycling and pyrolysis. Particularly, photocatalytic transformation of waste PS plastic has garnered significant interest in recent years. Photocatalytic techniques employ light energy to trigger radical reactions that break the stable C-C bond of PS. However, non-photocatalytic methods accomplish backbone breakdown without the need for direct light activation, frequently utilizing catalysts and thermal energy. Both methods efficiently convert waste PS into more valuable materials, including benzoic acid and acetophenone. The comprehension of reaction mechanisms enables the development of effective catalysts and their real-world applications. Our objective is to clarify catalytic mechanisms and principles of catalyst design, offering a direction for creating effective photocatalysts to improve catalytic efficiency, product specificity, and processing abilities for waste PS plastic. The persistent issues and prospective research paths in this domain are thoroughly examined, providing a guide for addressing the obstacles and advancing the discipline towards more sustainable waste management strategies.