Synthesis of BiOBr/Ag3PO4 heterojunctions on carbon-fiber cloth as filter-membrane-shaped photocatalyst for treating the flowing antibiotic wastewater.

Numerous nanosized photocatalysts have been demonstrated to treat antibiotic solutions efficiently in beakers, but plenty of antibiotics have been discharged to the flowing rivers. For photocatalytically degrading the flowing antibiotic wastewater, the prerequisite is to develop flexible large-scale filter-membrane with high photocatalytic activity. To solve this issue, with carbon fiber (CF) cloth as a flexible porous substrate, herein we have reported the in-situ growth of BiOBr/Ag3PO4 heterostructures. BiOBr nanosheets (thickness: ~10 nm, diameter: 0.5-1 μm) and Ag3PO4 particles (size: 50-200 nm) are synthesized on CF cloth successively via a solvothermal-chemical deposition two-step strategy. CF/BiOBr/Ag3PO4 cloth displays excellent visible photoabsorption (edge: ~520 nm). Under visible-light illumination, CF/BiOBr/Ag3PO4 cloth (4 × 4 cm2) could degrade ~90.0% tetracycline hydrochloride (TCH) as a model of antibiotics in 30 min in a beaker. Especially, CF/BiOBr/Ag3PO4 cloth can be used as the filter-membrane to construct multiple photocatalytic-setup for degrading the flowing antibiotic wastewater. The removal efficiency of TCH goes up from 12.8% at the first grade to 89.6% at the sixth grade. Furthermore, the photocatalytic mechanism of CF/BiOBr/Ag3PO4 cloth and the possible decomposition pathway of TCH have been proposed based on simulation and experiment results. Therefore, the present work provides some insight for developing flexible filter-membrane-shaped photocatalysts for degrading the flowing wastewater.