Effects of solvent composition on the synthesis of polydopamine Schiff base Cu complex to activate peroxymonosulfate for methyl-paraben degradation

Solvent composition plays an important role in the synthesis of metal complex materials, but to date little work on this issue has been reported. Herein, a unique Schiff base Cu complex catalyst (DPDA-Cu-95EtOH) was designed based on polydopamine (PDA) and 3, 5-dibromosalicylaldehyde (DBSA), and the influence of H2O added during the synthesis process on its catalytic performance towards peroxymonosulfate (PMS) activation was comprehensively investigated. Our results demonstrated that adding a small amount (5%, v:v) of H2O to the solvent absolute ethanol (EtOH) can greatly increase the Cu loading (from 3.56 at% to 10.30 at%) on the catalyst, which significantly enhanced its catalytic ability, and promoted the removal of MeP for about 4.6 times higher than that synthesized without addition of H2O. Electron paramagnetic resonance (EPR) and quenching tests revealed that 1O2, OH and SO4- were responsible for the degradation of Methyl-paraben (MeP). Moreover, the DPDA-Cu-95EtOH/PMS system not only showed excellent stability and reusability, but also exhibited considerable removal efficiency of MeP in real wastewater. Overall, this study provides new insights into the controllable synthesis of Schiff base metal complex used for the efficient activation of PMS to remove micropollutants in wastewater.