Interfacial biocatalytic removal of BPA and DBP by polydopamine-functionalized mesoporous silica-immobilized laccase

SiO 2 @PDA-Lac achieved BPA-dominant removal with synchronous DBP reduction. • PDA-coated mesopores enhanced pollutant enrichment and laccase anchoring. • SiO 2 @PDA-Lac retained BPA/DBP removal after 5 cycles and 50 d storage. • Docking and GC-MS revealed competitive binding and divergent pathways. • ECOSAR predicted overall toxicity reduction after enzymatic transformation. The potential co-occurrence of bisphenol A (BPA) and dibutyl phthalate (DBP) in contaminated water motivates the development of treatment strategies for binary pollutant systems. Herein, a polydopamine-functionalized mesoporous silica immobilized laccase system (SiO 2 @PDA-Lac) was developed for BPA-dominant removal and synchronous DBP reduction. Immobilization time was first selected by balancing initial activity and cycling stability. With the time fixed at 6 h, immobilization pH, temperature, and laccase concentration were further optimized by RSM using relative enzyme activity as the response, yielding pH 4.0, 25 °C, and 80 mg/mL laccase. In the binary system at an initial pollutant concentration of 100 mg/L, SiO 2 @PDA-Lac removed approximately 81% of BPA and 20% of DBP. Control experiments with free laccase and inactivated SiO 2 @PDA-Lac indicated that BPA removal was driven by coupled interfacial adsorption and enzymatic catalysis, whereas DBP reduction was lower but still measurably assisted by immobilized laccase. SiO 2 @PDA-Lac retained detectable performance after five cycles, with BPA and DBP removal remaining at 57% and 14%, respectively, and maintained removal activity after 50 d of storage. Molecular docking and molecular dynamics simulations suggested that BPA and DBP may occupy partially overlapping binding microenvironments. GC-MS and ECOSAR analyses indicated possible transformation pathways with an overall tendency toward lower predicted ecological risk. These results demonstrate the feasibility of SiO₂@PDA-Lac for BPA-dominant removal and concurrent DBP reduction in a model BPA/DBP binary system. Download: Download high-res image (314KB) Download: Download full-size image