Evaluation of photocatalysis inactivation in indoor air purification of pathogenic microbes by using the different nanomaterials based on TiO2 nanomaterials.

The photocatalytic technology for indoor air disinfection has been broadly studied in the last decade. Selecting proper photocatalysts with high disinfection efficiency remains to be a challenge. By doping with the incorporation of metals, the bandgap can be narrowed while avoiding the recombination of photogenerated charge. Three photocatalysts (Ag-TiO2, MnO2-TiO2, and MnS2-TiO2) were tested in photocatalytic sterilization process. The results revealed that Ag-TiO2 had the best antibacterial performance. Within 20 min, the concentration of Serratia marcescens (the tested bacteria) decreased log number of ln 4.04 under 640 w/m2 light intensity with 1000 µg/mL of Ag-TiO2. During the process of inactivating bacteria, the cell membranes of bacterial was destructed and thus decreasing the activity of enzymes and releasing the cell contents, due to the generation of reactive oxygen species (O2•- and •OH) and thermal effect. Spectral regulation has the greatest impact on the sterilization efficiency of MnO2-TiO2, which reduces the probability of photocatalytic materials being excited.

Microwave-assisted photocatalysis of neurotoxin compounds using metal oxides quantum dots/nanosheets composites: Photocorrosion inhibition, reusability and antibacterial activity studies.

Water pollution caused by different pollutants is one of the challenging tasks for the scientific community. We have prepared and characterized a material for removal of pollutant compounds. ZnO quantum dots decorated CuO nanosheets and TiO2 quantum dots decorated WO3 nanosheets composites have been prepared using a hydrothermal method. The as synthesized catalysts were characterized by various techniques. The crystallite sizes of CuO NSs and WO3 NSs were to be obtained 12.5 and 13.25nm and when dopped with ZnO and TiO2 size reduces to 3.2 and 3.9nm, respectively. The energy band gap of the CuO NSs, WO3 NSs, ZnO QDs/CuO NSs and TiO2 QDs/WO3 NSs composite are calculated to be 2.01, 2.61, 1.86 and 2.32eV, respectively. The prepared catalysts are efficiently utilized for the photocatalytic degradation of two neurotoxin compounds under UV and UV coupled with microwave irradiation. The prepared catalyst composites reveal excellent photocatalytic degradation of neurotoxin compound by degrading it up to 75% under UV and UV/microwave irradiation. The photocalysis efficiency in UV/microwave system is higher than UV system. The result shows that the ZnO QDs/CuO NSs and TiO2 QDs/WO3 NSs composites have excellent photocorrosion inhibition and reusability properties. Thus, prepared samples with positive surface potential upon interaction with negative surface potential of Enterococcus faecalis and Micrococcus luteus.