Effective adsorption of sulfamethoxazole by novel Organo-Vts and their mechanistic insights

摘要

The structural evolution of novel organo-Vts (modified by benzene- and amide-containing gemini surfactants with different alkyl chain lengths, PAC12, PAC14 and PAC16) was investigated and linked to the adsorption mechanism of sulfamethoxazole (SMX). The structures and surfaces of the resultant organo-Vts were specified by various probe techniques, such as FT-IR, XRD, TG and SEM. The dosage of surfactant was saturated as low as 0.4 CEC, a point of crucial importance for practical purposes. Adsorption capacities as a function of contact time, solution pH and concentration of the SMX were explored in detail. Intriguingly, the highest adsorption capacity achieved on PAC14-Vt (72.79 mg/g) can be reasonably attributed to suitable interlayer space, interlayer packing density and strong additional interactions. The adsorption of SMX onto organo-Vts was in agreement with pseudo-second-order, a non-spontaneous, and an exothermic process in nature. The consistency of SMX adsorption with Freundlich model may be resulted from the pi-pi staking interaction between the SMX molecules adsorbed and dissociated. To lucubrate the adsorption mechanism, the structure and character of the spent sample (PAC14-Vt) were adequately studied. The strength of pi-pi interaction weaker than the combination of hydrogen bond and NH-pi interaction in adsorption process was substantiated. This work confirmed that organo-Vts functionalized by functional gemini surfactants were promising adsorbents for mitigating antibiotics pollution and provided theoretical guidance for architecting high performance adsorbent.