Effect of environmental factors on enhanced adsorption and photocatalytic regeneration of molecular imprinted TiO2 polymers for fluoroquinolones

The molecular imprinting technique combined with photocatalysis was used in the removal of fluoroquinolones. In this study, we prepared molecular imprinted polymers (MIPs) and investigated the adsorption and photocatalytic regeneration performance, followed by the effect of different environmental factors and photoproduct identification. Compared with non-imprinted polymers (NIPs) and P25, MIPs had a better adsorption performance towards norfloxacin with the removal efficiency of 77.1% in 1 h. pH, humic acid, and high valence ions had significant effects on the adsorption performance. Under neutral condition, the adsorption effect of MIPs was better than that of acidic and alkaline condition. The removal efficiency declined to 25.9% when pH reached 11. The removal efficiency gradually improved with the concentration of humic acid increasing. The adsorption efficiency of MIPs in surface water was only 12.6% lower than that of ultrapure water, which indicated that molecular imprinting process improved the anti-interference property. The photodegradation rate was 0.114 min(-1) when the concentration of norfloxacin was 1 mg L-1. Norfloxacin was oxidized with aldehyde group or hydroxyl. The adsorption removal efficiency of MIPs did not decline apparently after 11 adsorption-photocatalytic regeneration cycles, which suggested that the in-situ regeneration and sustainable use of MIPs were achievable in organic pollutant control.