Hydroxyapatite-supported Ag-TiO2 as Escherichia coli disinfection photocatalyst.
A series of hydroxyapatite (HAP), 1wt% Ag-TiO(2) (AT1), 1wt% Ag-HAP and 5wt% AT1/HAP composite catalysts were prepared by incipient wetness and mechanical mixing methods. They were characterized by X-ray diffraction (XRD), FT-IR, SEM and ESCA analyses and their photocatalytic bactericidal activities were measured in suspension using Escherichia coli (E. coli), a water pollutant indicator. The surface analysis revealed that the Ag/Ti ratio is found to be ca. 0.0273 and also it indicated that the titania is present in the form of Ti(4+) and Ag is present as metallic silver. Both the XRD and ESCA analyses confirmed the phase of metallic Ag particles, which played a significant role on the bactericidal activity of the Ag doped TiO(2) catalysts. The FT-IR analysis of HAP revealed that the peak intensity is due to the absorbance of surface PO(4)(3-) group centered at wave number 1030cm(-1) and is drastically decreased upon exposure to UV for 1h. The HAP displayed high amount of bacteria adsorption, ca. 80% during the dark experiments compared to other catalytic systems tested. The cumulative photocatalytic properties of AT1/HAP catalytic system resulted in 100% E. coli bacteria reduction within 2min.
Pratap Reddy
M
M
Catalysis and Physical Chemistry Division, Indian Institute of Chemical Technology, Hyderabad 500 007, India.
Venugopal
A
A
Subrahmanyam
M
M
D000327:Adsorption; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002384:Catalysis; D004926:Escherichia coli / Q000187:drug effects*; D006882:Hydroxyapatites; D008855:Microscopy, Electron, Scanning; D010777:Photochemistry; D018030:Silver Compounds / Q000494:pharmacology*; D014025:Titanium / Q000494:pharmacology*; D014466:Ultraviolet Rays; D018508:Water Purification / Q000379:methods*
D000900:Anti-Bacterial Agents; D006882:Hydroxyapatites; D018030:Silver Compounds; C009495:titanium dioxide; D014025:Titanium