A Study Of Photocatalytic Degradation Of Organic Pollutants On Au-TiO₂/Bentonite

We prepared Au-TiO₂/bentonite sample by deposition-precipition method. The effect of calcination temperature and the loading amount of Au were studied.The photocatalytic activities of the sample were tested by photodegradation rate of sulfordamine B(SRB)and COD change rate of SRB under ultraviolet(UV) and visible light irradiation.These samples were characterized by XRD,DRS,BET and XPS.The experimental results showed:Au-TiO₂/bentonite catalyst had a higher photocatalytic activity and a larger specific area when calcination temperature is300℃and 400℃.Furthermore,the COD change rate of sulfordamine B(SRB) was80.5%,83.9%and 92.0%under UV light irradiation of 10b on P25 and Au-TiO₂/bentonite catalyst calcinated at300℃and 400℃,respectively.The COD change rate of sulfordamine B(SRB) was 7.0%,8.8%and 8.9%under visible light irradiation of 136h on P25 and Au-TiO₂/bentonite catalyst,respectively.We found that Au-TiO₂/bentonite catalyst had higher efficiency to mineralize sulfordamine B(SRB) than P25 under UV light and visible light irradiation.The life time of Au-TiO₂/bentonite catalyst calcinated at 400℃was long and it was a very stable catalyst. Au-TiO₂/bentonite catalysthad a higher photocatalytic activity and a larger specific area when Au loading amount is 1.9%.Furthermore,the COD change rate of sulfordamine B(SRB) was 83.5%and 92.0%under UV light irradiation of 10h on P25 and Au-TiO₂/bentonite catalyst,respectively.The COD change rate of sulfordamine B(SRB) was 10.3%and 20.2%under visible light irradiation of 105h on P25 and Au-TiO₂/bentonite catalyst,respectively. We found that Au-TiO₂/bentonite catalyst had higher efficiency to mineralize sulfordamine B(SRB) than P25 under UV light and visible light irradiation. Au-TiO₂/bentonite catalyst can be readily separated from aqueous suspensions by sedimentation after the reaction.