Screening on the sorption of emerging contaminants to polystyrene and polyethylene and use of coagulation – flocculation process for microplastics’ removal

In this study, preliminary experiments were conducted to investigate the sorption potential of different organic micropollutants to polystyrene and polyethylene and to examine the removal efficiency of these microplastics during coagulation experiments with iron and manganese coagulants. For the sorption experiments, eight synthetic chemicals which belong to three different categories, pharmaceutical compounds, personal care products and endocrine-disrupting compounds were used. Among target compounds, important removal due to sorption to microplastics was noticed for the antihypertensive drugs Valsartan and Losartan, when polystyrene was used as sorbent material. Their sorption was a slow and gradual process; 20% of valsartan and 59% of losartan was sorbed after 168 h. On the other hand, no sorption of parabens, bisphenol A and sulfamethoxazole was observed. The elaboration of coagulation experiments showed that polystyrene is removed to a higher percentage comparing to polyethylene, reaching 92.4% and 72.1%, respectively. The higher removal of polystyrene was achieved when ferrous sulfate or magnesium sulfate was added, while the use of ferric chloride did not improve its removal. Increased removal of polyethylene was achieved when magnesium sulfate was used. Further experiments should be conducted to investigate the parameters affecting sorption of valsartan and losartan to microplastics and the mechanisms governing removal of polystyrene and polyethylene during coagulation.