Fabrication of 3D lignosulfonate composited sponges impregnated by BiVO4/polyaniline/Ag ternary photocatalyst for synergistic adsorption-photodegradation of fluoroquinolones in water

Abstract

In this work, a 3D lignosulfonate composited poly(vinyl formal) (PVF) sponge impregnated by BiVO4/polyaniline (PANI)/Ag ternary photocatalyst (PLS-BiVO4/PANI/Ag) was designed and fabricated. The synergistic adsorption-photodegradation of five fluoroquinolones (FQs) antibiotics onto PLS-BiVO4/PANI/Ag was investigated. Incorporating lignosulfonate as a carrier on PVF sponge improved its structural properties and enhanced its adsorption performance toward FQs. The BiVO4/PANI/Ag ternary photocatalyst was well-dispersed and tightly bound to the composited sponge, thus it efficiently degraded the adsorbed FQs through surface photodegradation. PLS-BiVO4/PANI/Ag achieved >90% removal efficiency for all examined FQs within 2.0 h in a batch system, while it maintained a steady 80% removal efficiency for 30.0 h in a continuous dynamic treatment system. Photoelectric characterizations and ESR results showed that BiVO4/PANI/Ag was consistent with the type II heterostructure and effectively improved the utilization of visible light and the separation of photogenerated electron-hole pairs. The hole was the dominant active species in the degradation of FQs, while the main degradation pathways included defluorination, decarboxylation and destruction of piperazine ring. The prepared composited sponge is thus characterized by its high performance, convenient operation, eco-friendliness, and practicality in real water treatment systems since it undergoes self-purification and is easily recovered from water without mass loss.