Polymer/BiOBr-Modified Gauze as a Dual-Functional Membrane for Heavy Metal Removal and Photocatalytic Dye...

It is crucial to remove heavy metals and dyes before discharging industrial effluents. Gauze substrate was surface-modified by coating with a polymeric adsorbent and a spray coating of BiOBr photocatalyst to develop a novel dual-functional membrane, polymer/BiOBr-modified gauze, for water remediation. The polymeric adsorbent was crosslinked to prevent the dissolving of the adsorbent during operation in contaminated water. The morphology and surface chemistry of the modified gauze were characterized before and after the adsorption of Ni²⁺. The surface wettability, isotherms, and kinetics of Ni²⁺ adsorption were studied. We also studied the effect of pH, initial Ni²⁺ concentration, monomer molar ratio, and monomer chemical structure on the Ni²⁺ adsorption capacity. To achieve a high Ni²⁺ adsorption capacity and good photocatalytic decolorization activity, the amount of decorated BiOBr was tuned by changing the spray-coating time to optimize the exposed BiOBr and polymer on the surface. The optimized dual-functional membrane PB20 possesses excellent adsorption capacity (650 mg g^-1) for Ni²⁺ ions and photocatalytic decolorization activity (100% degradation of RhB within 7 min). Decorating the optimized amount of BiOBr on the surface can introduce photocatalytic decolorization activity without sacrificing the adsorption capacity for Ni²⁺.