Immobilised Humic Substances as Low-Cost Sorbents for Emerging Contaminants

Environmental pollution with contaminants of emerging concern (CECs) is a worldwide problem that is receiving increasing attention. Although these substances have been released in the aquatic environment for a long time, wastewater treatment plants are still incapable of removing emerging contaminants completely. Consequently, trace metals, metalloids and pharmaceuticals, as well as surfactant leftovers, are often found in environmental samples. Environmentally friendly and cost-effective sorbents such as humic substances can be used for purification if their sorption properties are increased by immobilization. To our knowledge, immobilized humic substances have not been widely studied as sorbents up to now. In this study, humic substances were immobilized to obtain low-cost sorbents. The chosen methods for characterization of the obtained sorbents showed successful immobilization. Traditional pollutants, such as Cr(III) (a metal), As(V) (a metalloid) and chlorpromazine (a pharmaceutical), were used as representative contaminants. Sorption experiments were conducted using the batch system, and sorption was also studied based on the sorbent dosage, initial concentration of the studied element or substance, solution pH and sorption time. The results show that all the obtained immobilized humic substances in this study can be used as sorbents to remove contaminants from water. At the same time, from these humic substances, only those immobilized using iron compounds are suitable for the removal of arsenic.