Exploring the potential of flexible CdS/ZnO/Polyurethane nanocomposite membrane for wastewater remediation

To solve the recovery problem of nanosized powder form of photocatalysts, our work was devoted to develop a macroscale membrane-shaped photocatalyst with outstanding efficiency as well as high stability. Specifically, zinc oxide (ZnO) and cadmium sulfide (CdS) nanoparticles were successfully loaded onto the polyurethane (PU) matrix through blending and in-situ growth way, respectively. The introduction of ZnO can effectively improve the membrane hydrophilicity and endow it with some photo-catalysis capability without disturbing membrane structural integrity. After the construction of CdS/ZnO heterojunction, the photocatalytic activity obtained further enhanced. Compared with ZnO/PU (ZP) and CdS/PU (CP), CdS/ZnO/PU composite membrane (CZP) displayed the highest photocatalytic performance. The efficiency of CZP in the degradation of potassium ethyl xanthate (PEX) reached up to 97.06%, which is 7.21 and 5.42 times higher than the ZP and CP, respectively. Furthermore, CZP also exhibited satisfactory performance for removing multifarious refractory organic pollutants including potassium butyl xanthate, potassium amyl xanthate, Rhodamine B, methylene blue, crystal violet, tetracycline, and levofloxacin. Finally, the possible photocatalytic reaction mechanism of representative PEX contaminant over CZP membrane surface was discussed in detail. Overall, this novel composite porous membrane exhibited outstanding application potential in wastewater remediation.