The influence of Pb(II) adsorption on (Non) biodegradable microplastics by UV/O3 oxidation treatment

Widely distributed in the natural environment, microplastics (MPs) may serve as carriers for adsorbing and carrying heavy metal. More research is still required to understand the aging process of MPs and interactions between MPs and heavy metals. In this study, we are going to explore the effects of UV/O3 oxidation on the adsorption behavior of Pb(II) on MPs. The MPs that we include in our study are conventional MPs (PE, polyethylene) and biodegradable MPs (PLA, polylactic acid). The results showed that the UV/O3 oxidation significantly increased its specific surface area and oxygen content, thereby enhancing the adsorption capacity of Pb(II) on MPs. Further, the physicochemical properties of PLA are changed much more than PE after UV/O3 oxidation. In this study, the adsorption process conformed to the pseudo-second-order kinetic and the intraparticle diffusion models, and the adsorption order was aged PLA > aged PE > original PLA > original PE. Their maximum adsorption capacities were 0.98 mg/g, 0.83 mg/g, 0.67 mg/g and 0.54 mg/g, respectively. Studies have implied that the oxidation degree and types of MPs have an impact on their interactions with co-existing pollutants. Overall, These studies indicate that oxidation treatment can alter the structural properties of microplastics while also revealing the Pb(II) sorption kinetics and mechanisms onto the MPs, which will help researchers better understand how MPs interact with heavy metals.