Preferential removal of 2,4-dichlorophenoxyacetic acid from contaminated waters using an electrocatalytic ceramic membrane filtration system: Mechanisms and implications

A selective electrocatalytic ceramic membrane filtration (ECMF) system was developed using molecular imprinting (MI) TiO 2 @SnO 2 -Sb (MI-TiO 2 @SnO 2 -Sb) anode for selectively eliminating 2,4-dichlorophenoxyacetic acid (2,4-D). The introduction of MI sites enhanced the removal of 2,4-D compared to the control. At a charging voltage of 3 V under flow-by mode, the 2,4-D removal rate of MI-TiO 2 @SnO 2 -Sb ECMF system was 1.91 times that of the control (without MI), attributed to the specific recognition sites (leading to selectivity) and the enhanced reactive oxygen species production in the presence of MI sites. In the coexistence of interferent phenoxyacetic acid herbicides, MI-TiO 2 @SnO 2 -Sb ECMF system also showed higher selective coefficient than the control (without MI). More importantly, flow-through mode could enhance the selectivity since the membrane filtration enhanced the mass transfer of target micropollutant towards MI sites. The imparted selectivity was mainly attributed to the size matching and special interaction between the target molecules and imprinted cavities.