Accurate removal of trace sulfonamides using selective electrocatalytic oxidation in complex water

Accurate removal of antibiotics like sulfonamides (SAs) under the interference of co-existing contaminants with high concentrations is challenging. In this study, a lead dioxide electrode modified with a novel surface molecular imprinting technology (SMI-PbO₂) was synthesized, utilizing a core structure pseudo template featuring sulfonyl, benzene ring, and amino groups as characteristic functional groups for SAs recognition. The SMI-PbO₂ electrode demonstrated target identification towards SAs, even when exposed to interferents at a ratio of 1:1000, and achieved efficient simultaneous removal of six SAs (initial concentration: 150 μg L⁻¹) in aqueous matrices containing high concentrations of co-existing interferents (150 mg L⁻¹). The mechanism underlying target recognition and the selective removal of group-targeted SAs was elucidated through various in situ techniques and theoretical calculations. These analyses revealed that robust electronic interactions between the sulfonyl group of SAs and Pb sites within the imprinting cavities, coupled with terminal hydrogen bonding involving the amino group, facilitated the selective recognition of target SAs. Furthermore, under high applied potentials, self-optimization of the SMI-PbO₂ electrode enabled the imprinting cavities to consistently capture target molecules despite vigorous competitive adsorption. Subsequent rapid desorption of intermediates following bond cleavage and re-adsorption of new target contributed to the accurate removal of SAs.