Sol-gel membrane modification for enhanced photocatalytic activity

Novel materials comprising titanium dioxide (TiO2), silicon dioxide (SiO2) and silicon carbide (SiC) semiconductors, were deposited over silicon-carbide substrates to develop photocatalytic membranes. The synergistic effect between TiO2 obtained by sol–gel process, Degussa P25 and silicon carbide nanoparticles were tested in terms of photocatalytic degradation of methylene blue and their influence over porosity. The surface of the photocatalyst layers developed were characterized by scanning electron microscopy (SEM) showing that the immobilization was carried out successfully whereas the contact angle measurements revealed improved hydrophilic properties. Different surface properties were obtained depending on the different coating compositions applied. Several photocatalytic experiments were conducted and reproducibility was tested using the most promising membranes in terms of photodegradation potential that reached up to 72% degradation of methylene blue. Comparison of UV degradation efficiency between unmodified and modified substrates revealed a synergistic effect when TiO2 and SiC were combined. The most promising membrane in terms of photocatalytic effectiveness and reusability was modified with SiO2 obtained by sol-gel combined with Degussa TiO2 nanoparticles. This membrane was used in a dead-end filtration system combined with UV light. Results confirmed the photocatalytic activity of the membrane combined with filtration, showing that the modified membranes have a high potential to degrade organic contaminants.