BiOI-embedded molecularly imprinted polymer-functionalized BiOIO3 photocatalyst with spatially coupled dual-active sites for efficient selective citalopram removal

Abstract

Achieving high-selectivity priority identification and degradation of target pollutants in complex water environments using photocatalytic technology remain challenging. Herein, we proposed a novel strategy for the simultaneous formation of BiOI and imprinting polymers on the BiOIO₃ substrate to obtain a molecularly imprinted photocatalyst (EMI-Bi/Bi4) capable of highly selective adsorption and degradation of citalopram (CIT) in complex media. The prepared EMI-Bi/Bi4 exhibited excellent selective recognition ability toward the template molecule CIT, with a theoretical maximum adsorption capacity of 343.68 mg g⁻¹ and an imprinting factor of 7.2. In the coexisting system of CIT and CBZ, the adsorption selectivity coefficient (K) of EMI-Bi/Bi4 was as high as 26.936, and the degradation selectivity factor (α) exceeds 3.12. Under a wide pH range (3−11) and presence of humic acid, the CIT removal efficiency of EMI-Bi/Bi4 exceeded 93%. Even after seven consecutive cycles, the CIT removal efficiency remained above 84%. Precise imprinting site identification and effective photoactive species utilization enabled highly selective CIT removal in urban wastewater, achieving ≥ 90.3%, which was 17% higher than that of traditional surface-imprinted photocatalysts. DFT simulations and microstructure characterization confirmed that the highly selective CIT removal by EMI-Bi/Bi4 is due to hydrogen bonds, van der Waals forces, and electrostatic interactions between CIT and functional monomers; as well as the imprinted cavities highly matching the spatial structure of CIT and the highly overlapping imprinted sites and degradation sites formed by BiOI embedding in the imprinted polymer. This strategy enhances the concept of the highly selective identification and efficient photocatalytic degradation of targets in actual water.