Constructing mesoporous Zr-doped SiO2 onto efficient Z-scheme TiO2/g-C3N4 heterojunction for antibiotic degradation via adsorption-photocatalysis and mechanism insight

Novel modified-TiO2/Zr-doped SiO2/g-C3N4 ternary composite is fabricated via an in-situ grow of porous Zr–SiO2 layer to TiO2/g-C3N4 heterojunction, which exhibits well adsorption-photocatalytic performance under simulated solar light irradiation. The nano-size mesoporous TiO2 are dispersed on the lamellar g-C3N4, and the Zr–SiO2 is in-situ fabricated onto the surface of g-C3N4 sheets. The adsorption occurs on the SiO2 layers, and doping Zr element to SiO2 enhances the adsorption of pollutants, while the photocatalytic reaction occurs on the valence band (VB) of TiO2 and conduction band (CB) of g-C3N4, which gives reactive oxygen species of ∙O2−, h+, and ∙OH for high efficient decomposition of antibiotics, i.e. berberine hydrochloride (98.11%), tetracycline (80.76%), and oxytetracycline (84.84%). The excellent adsorption capacity and Z-scheme photoinduced charge carrier migration behavior endowed the novel material with enhanced berberine hydrochloride (BH) removal in water, which approximately 2.5 and 3.8 folds than that of pure g-C3N4 and sole TiO2, respectively. Three degradation pathways are unraveled by LC-MS and theoretical calculations. Furthermore, the toxicity of intermediates was evaluated by the Toxicity Estimation Software Tool (T.E.S.T.), the result demonstrated a good application potential of M-TiO2/Zr–SiO2/g-C3N4 as an novel adsorptive photocatalyst. [Display omitted] •Zr–SiO2 slice is introduced onto the Z-scheme TiO2/g-C3N4 to obtain high adsorption.•The ternary sample exhibits high performance in static and in continuous flow tests.•The ternary composite shows coupled adsorption-photocatalysis activity to BH removal.•Toxicity of BH and its photocatalytic degradation intermediates are evaluated.•Adsorption-photocatalysis coupling mechanism of the ternary composite is proposed.