Coagulation studies on photodegraded and photocatalytically degraded polystyrene microplastics using polyaluminium chloride

•Photo and photocatalytic degradation of PS under UV-C, UV-A and solar irradiation.•Photodegradation using UV light is effective in removal of polystyrene microplastic.•Oxygen to carbon ratio of polystyrene microplastics increased after UV irradiation.•Large sized MPs (300–150 μm) showed better removal efficiency under UV-C irradiation.•Tentative degradation pathway of photodegraded PS microplastic by FTIR analysis. Microplastics are ubiquitous persistent emerging contaminants, and its presence has been detected even in the most pristine and fragile ecosystems. Advanced oxidation processes are one of the novel degradation technologies used for the elimination of microplastics from the environment. In this study, the effect of ultraviolet C (UV-C, 253.7 nm) and ultraviolet A (UV-A, 365 nm) irradiations on polystyrene (PS) microplastic properties in the presence and absence of titanium dioxide were studied along with their coagulation performances using polyaluminium chloride (PAC). The effects of solar irradiation on the chemical properties of microplastics in aqueous and dry conditions were also investigated. PS microplastics (1.5 g) in three size ranges, 300–150 μm, 150–75 μm, and