A novel Z-scheme AgI/Bi2MoO6 hybrid photocatalyst was fabricated via a solvothermal-precipitation approach to disinfect bacteria in water. Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopic (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscope (HRTEM), UV-vis diffuse reflectance spectra (DRS), as well as photoluminescence spectra (PL) were employed to characterize the fabricated photocatalyst. Due to the stronger redox potential and better separation of charge carriers induced by the Z-scheme structure, the optimal synthesized AgI/Bi2MoO6 exhibited excellent disinfection activity towards both Gram-negative strain Escherichia coli (E. coli) and Gram-positive strain Staphylococcus aureus (S. aureus) under visible light irradiation. 5.0 × 107 CFU mL−1 of E. coli and S. aureus cells were completely disinfected within 30 min and 90 min, respectively. Ag+ ions did not contribute to the disinfection activity, while active species including h+, ·O2−, e-, and H2O2 contributed to the cell inactivation. By changing the interaction force and being involved in the photocatalytic reactions, the common anions (Cl−, NO3−, SO42−, and H2PO4−) would affect the disinfection activity. Moreover, AgI/Bi2MoO6 exhibited effective disinfection activity in four consecutive reused cycles. Thus, AgI/Bi2MoO6 could be used as a promising photocatalyst for water disinfection.

The influence of Bisphenol A (BPA) on the transport and deposition behaviors of bacteria in quartz sand was examined in both NaCl (10 and 25 mM) and CaCl2 solutions (1.2 and 5 mM) by comparing the breakthrough curves and retained profiles of cell with BPA in suspensions versus those without BPA. Gram-negative Escherichia coli and Gram-positive Bacillus subtilis were employed as model cells in the present study. The extended Derjaguin-Landau-Verwey-Overbeek interaction energy calculation revealed that the presence of BPA in cell suspensions led to a lower repulsive interaction between the cells and the quartz sand. This suggests that, theoretically, increased cell deposition on quartz sand would be expected in the presence of BPA. However, under all examined solution conditions, the presence of BPA in cell suspensions increased transport and decreased deposition of bacteria in porous media regardless of cell type, ionic strength, ion valence, the presence or absence of extracellular polymeric substances. We found that competition by BPA through hydrophobicity for deposition sites on the quartz sand surfaces was the sole contributor to the enhanced transport and decreased deposition of bacteria in the presence of BPA. © 2017