Contaminants of emerging concern (CECs) adsorption on superfine activated carbon

Abstract

Contaminants of emerging concern (CECs) adsorption on superfine powdered activated carbon (S-PAC) (0.6 μm mean size) at conventional water treatment plants (WTP), where feasible contact time is usually shorter than 2 hours, was analyzed. Laboratory-scale experiments were carried out having deionized water (DW) and raw water (RW) samples fortified for atrazine (ATZ), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2). Adsorption diminished due to natural organic matter, but in a smaller extension for S-PAC. Multi-solute removal efficiencies kept the same ranking for DW and RW, i.e., E2 > EE2 > ATZ, following compounds' hydrophobicity and molecular size. Hydrophobic and H-bonding interactions were the main adsorption mechanisms. For all target compounds the adsorption process was controlled by film diffusion. S-PAC presented higher adsorption as well as lower desorption as compared to powdered activated carbon, achieving similar efficiencies for half dosage and same contact time or at half contact time and same dosage. Physicochemical processes at WTP are capable to remove contaminated S-PAC particles. HIGHLIGHTS S-PAC efficiencies are comparable to PAC at half contact time or dosage.; After 2 hours (feasible at WTP), CECs removal increased up to 73%, for 10 mg/L S-PAC dosage.; Elovich and Weber-Morris models fit target CECs adsorption kinetics on S-PAC.; H-bonding rather than Π-stacking interaction is the main adsorption mechanism.; Physicochemical processes at WTP are capable to avoid contaminated S-PAC particles in tap water.;

Keywords

• 17α-ethinylestradiol
• 17β-estradiol
• adsorption
• atrazine
• superfine activated carbon
• water treatment