A catalytic membrane based on dopamine directional deposition biomimetically induced by immobilized enzyme for dye degradation

Dopamine-assisted deposition technology is widely used in functional modification of polymer membranes due to the advantages such as simple operation, mild reaction, and strong adhesion to materials. Limited by the major defects of spontaneous polymerization in an alkaline environment and non-selective adhesion, it is still challenging to achieve directional deposition, stability, and fast deposition rate at the same time. Herein, inspired by tyrosinase-induced melanin directional deposition on the skin, we present a biomimetic catalysis strategy for the directional deposition of dopamine on the target surface. By immobilizing laccase on the target surface, the oxidative self-polymerization of dopamine can be inhibited, and the biomimetic induced directional deposition on membrane can be achieved. The biomimetic catalytic membrane covered with a uniform and stable laccase-dopamine coating can be used for the degradation of azo printing and dyeing wastewater. Moreover, the degradation efficiency of the catalytic membrane for methyl orange can reach 19.8 μg/min, and the relative activity can still be maintained at about 81% after 6 cycles, showing high catalytic activity and stability.