Zinc oxide nanoparticles immobilized on polymeric porous matrix for water remediation

Abstract

This work proposes a novel approach to producing composite membranes by immobilizing and blending ZnO nanoparticles within a polymer matrix. The focus is investigating how different immobilization techniques impact membrane performance in critical technological applications, including membrane fouling mitigation and photocatalytic degradation. Lab-synthesized ZnO nanostructures were immobilized within a natural cellulose acetate (CA) matrix using a spray coating technique. To ensure comprehensive exploration, CA membranes with 12% and 15% wt polymer concentrations, which demonstrated superior overall performance in previous studies, were cast and prepared. The membranes underwent phase inversion, and a specially prepared ZnO solution was sprayed onto the membrane surface, creating a unique blend of polymer and nanoparticles. This comparative study highlights distinctions between nanomaterial immobilization techniques (mixing and spray coating) while maintaining identical polymer content. Such insights are crucial for both industrial applications and laboratory-scale research. The photocatalytic degradation of the reactive and toxic dye methylene blue (MB) served as a model reaction, employing a UV light module. Results unequivocally demonstrated that, irrespective of the immobilization technique employed, the combination of CA and ZnO nanoparticles significantly enhanced the photocatalytic activity of the membrane in degrading methylene blue (MB). Specifically, the dye concentration decreased from 25 to approximately 8 mg/L for both the spray coating and bulk immobilization methods, resulting in 62% and 69% dye degradation, respectively. These findings underscore the versatility of different immobilization techniques in various aspects of membrane technology. The CA-ZnO composite exhibited efficacy in photocatalytic MB degradation tests, offering promising alternatives for designing polymeric membranes tailored for contaminant removal, particularly in treating textile dye-contaminated aqueous solutions. The exploration of diverse immobilization techniques for nanocomposites presents an exciting avenue for optimization in different membrane technological processes.