Adsorption and photochemical capacity on 17α-ethinylestradiol by char produced in the thermo treatment process of plastic waste

Plastic is a major component of solid waste. It is often thermally treated, generating microplastics and plastic-char which end up as landfill. This study investigated the potential of plastic-char for treating persistent organic pollutants of aqueous media using 17α-ethinylestradiol (EE2) as a target contaminant. The adsorption and photodegradation capacity of plastic-char were investigated, and the adsorption isotherms revealed that EE2 adsorption on char is heterogeneous and multilayered. The presence of Fe was found to greatly enhance EE2 adsorption rate and capacity as well as photochemical degradation ability of plastic-char. Quenching experiments proved that electron transfer between triplet states of plastic-char and Fe(III) and the production of HO were the rate-limited steps in the generation of reactive species. Hydroxyl radical and holes were found to be the predominant reactive species contributing to the EE2 photodegradation. This study not only elucidated the possible environmental behavior of plastic-char discharged as bottom ash in the natural transformation of persistent organic pollutants, but also suggested that water treatment may offer a use for some of the enormous volume of plastic waste now being generated worldwide.