The Deactivation Mechanism of Photocatalyst Inactivation of Bacteria Caused by Complex Components in Mariculture Water
Photocatalysis has good application prospects for the purification of aquacultural water.However,the composition of seawater aquaculture water is complex and the mechanism of photocatalyst deactivation has rarely been studied.In this study,a typical offshore aquaculture water body was selected as the research object,focusing on the mechanism of bactericidal inactivation of photocatalyst TiO2 nanotubes,with humic acid as the typical natural organic matter(NOM)component and bacteria and fungi as the main microorganisms.The results showed that bacteria(k=0.23 h-1)and fungi(k=0.32 h-1)had high bactericidal efficiency during 0‒8 h in Shantou mariculture water,and the bactericidal efficiency(k=0.03 h-1)began to decline during 8‒24 h,the same trends were observed in Zhanjiang mariculture water.In the Zhuhai mariculture water body,the killing efficiency of bacteria(k=0.14 h-1)was high in the first 0‒8 h,and that of fungi was also high at 0‒6 h(k=0.24 h-1).In addition,the water samples from the three sites showed an increase in the number of bacteria after 48 h,48 h and 8 h respectively,which may be related to the VBNC state of bacteria.At the same time,the determination of microbial diversity revealed that Pseudomonas was the dominant strain in mariculture water.Chlamydia,Mycoplasma,and Legionella showed the greatest reduction in the proportion of bacteria during the killing process.The degradation degree of humic acid in water samples from three different areas was above 40%using a steady-state transient fluorescence spectrometer combined with PARAFAC and fluorescence region integration(FRI).The bactericidal efficiencies of the bacteria and fungi changed significantly at 8 and 6 h,respectively.At the same time,through microbial diversity,ATR-FTIR,SEM-EDS,and other experimental characterizations,it was found that during the sterilization process,humic acid intermediates and biomolecules were broken and leaked by bacteria attached to the surface of the TiO2 nanotubes and blocked some micropores,resulting in accelerated deactivation of the photocatalyst.In this study,the deactivation phenomenon and mechanism of photocatalysis applied to water treatment in complex environments were studied,filling the gaps in this field.
photocatalyst deactivationTiO2 catalystmariculture waterinactivation of microorganismshumic acid
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