Mixed matrix membrane reactor containing core-shell 4A-Fe@Cu Fenton catalyst for high-performance removal of congo red

Printing and dying wastewater has a pervasive problem afflicting people worldwide due to negative impacts on ecosystems and humans. Herein, Fe/Cu bimetallic catalyst/polyethersulfone (4A-Fe@Cu/PES) mixed matrix membrane (APMMM) with macropore and high porosity were developed as catalytic membrane reactor for reduction of congo red (CR) in flow-through reaction. The forced flow of the reactants through the membrane improved the mass transfer and intensified the contact between reactants and immobilized catalysts, allowing for efficient adsorption and catalysis. Furthermore, the CR adsorption by 4A-Fe@Cu would form catalytic microzones in the membrane, which was conducive to further improving the catalytic efficiency. As a result, the apparent activation energy of dynamic catalysis (21.1 kJ/mol) was significantly decreased compared with that of static catalysis (93.7 kJ/mol). Therefore, the dynamic processes exhibited more excellent adsorption and catalytic efficiency. In cross-flow circulation mode, the maximum CR adsorption capacity of APMMM-18 (doping amount of 4A-Fe@Cu is 18.0 wt%) was 199.5 mg/g4A-Fe@Cu with a catalyst/CR mass ratio of 1/1.5 and initial CR concentration of 50 mg/L. For catalysis, the APMMM-18 could remove 99.8 % CR after 5 h with a catalyst/CR mass ratio of 1/1.5 and 1.9 mM of H2O2 at pH 8. The catalytic membranes showed much higher performances than 4A-Fe@Cu particles even under lower H2O2 conditions. The intrinsic CR adsorption and degradation ratio of one layer of APMMM-18 under dead-end filtration was also investigated. The combination of the Fenton catalyst with the membrane process accomplished the effective removal of CR.