Enhanced removal of polyethylene terephthalate microplastics through polyaluminum chloride coagulation with three typical coagulant aids

Given the discovery and hazard of microplastics in freshwater environments, the removal of microplastics in drinking water deserves more attention. Nevertheless, in the light of existing literature, the effectiveness of conventional coagulation on microplastics removal is insufficient. Hence, enhanced coagulation is worth being explored. This study investigated the improving performance of anionic polyacrylamide (PAM), sodium alginate (SA), and activated silicic acid (ASA) when using poly-aluminum chloride (PAC) to remove polyethylene terephthalate (PET) microplastics. The experimental results showed that ASA had the highest removal efficiency (54.70%) under conventional dosage, while PAM achieved the best removal effect (91.45%) at high dosage. Mechanism of coagulation was studied by scanning electron microscope (SEM), Fourier transform infrared spectroscope (FTIR), X-ray photoelectron spectroscopy (XPS), and the results illustrated that when only PAC existed or the dosage of coagulant aids was low, double layer compression was the main principle. The increase of coagulant aids dosage improved the effect of adsorption and sweep flocculation significantly. Moreover, jar tests carried in different conditions demonstrated that the current coagulation systems were highly adaptable. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the performance of anionic polyacrylamide (PAM), sodium alginate (SA), and activated silicic acid (ASA) in enhancing the removal of polyethylene terephthalate (PET) microplastics using poly-aluminum chloride (PAC). The results showed that ASA had the highest removal efficiency at conventional dosage, while PAM achieved the best removal effect at high dosage. The mechanism of coagulation was studied, and increasing the dosage of coagulant aids significantly improved the effect of adsorption and sweep flocculation. Additionally, jar tests demonstrated that the current coagulation systems were highly adaptable.