Removal of micro pollutants using activated biochars and powdered activated carbon in water

Abstract:

Recent studies have suggested that emerging micropollutants containing endocrine disrupting compounds (EDCs); bisphenol A, 17 α-ethinylestradiol, 17 β-estradiol and pharmaceuticals and personal care products (PPCPs); sulfamethoxazole, carbamazepine, ibuprofen, atenolol, benzophenone, benzotriazole, caffeine, gemfibrozil, primidone, triclocarban in water have been linked to ecological impacts, even at trace concentrations (sub ug/L). Adsorption with adsorbent such as activated carbon having a high-binding affinity has been widely used to eliminate various contaminants in the aqueous phase. Recently, an efficient treatment strategy for EDCs and PPCPs has been considered by using cost effective adsorption particularly with biochar in aqueous environmentIn this study, the objective of this study is to determine the removal of 13 target EDCs/PPCPs having different physicochemical properties by a biochar at various water quality conditions (pH (3.5, 7, and 10.5), background ions (NaCl, CaCl₂, Na₂SO₄), ionic strength, natural organic matter (NOM)). The activated biochar produced in a laboratory was also characterized by using conventional analytical methods as well as advanced solid-state nuclear magnetic resonance (NMR) techniques, which answer how these properties determine the competitive adsorption characteristics and mechanisms of EDCs and PPCPs.The primary findings suggest that micropollutants can be removed more effectively by the biochar than the commercially available powdered activated carbon. At pH values below the pK_a of each compound, the adsorption affinity toward adsorbents increased significantly with the pH, whereas the adsorption affinity decreased significantly at the pH above the pK_a values. Na⁺ did not significantly impact adsorption, while increasing the concentration of Ca²⁺lead to increase in the adsorption of these micropollutants. NOM adsorption with humic acids on these adsorbents disturbed adsorption capacity of the target compounds as occupying active adsorption sites and interacting with EDCs/PPCPs. Conclusion that can be drawn thus far is that the biochar shows great physicochemical properties for adsorption to reduce the micropollutants.