Fabrication of Porous Metallic Bismuth-Based Blocks via 3D Printing and Their Performance in Chloride Removal
High-concentration chloride ions (Cl−) in industrial wastewater cause severe corrosion and environmental hazards. Conventional removal methods suffer from low efficiency, high cost, and difficulty in product recovery. This study fabricated porous metallic bismuth-based blocks (Bi-PM) via 3D printing, combining chemical precipitation with additive manufacturing. Systematic evaluation of Cl− removal under varying pH and light irradiation revealed that at pH 0.1 and 0.5, dark-condition efficiencies were 53.6% and 31.0%, respectively, increasing to 69.3% and 38.1% under light. Radical trapping identified photogenerated holes as the primary active species, oxidizing metallic Bi to release Bi3+ and enhance precipitation. At pH 0.5, Bi-PM exhibited balanced efficiency and structural stability; over five cycles, average removal efficiency was 25% in darkness versus 41.2% under light, with superior stability under illumination. XRD and SEM confirmed abundant BiOCl formation on the surface under light, mitigating Bi loss. This approach ensures high chloride removal while minimizing material degradation, offering a novel pathway for industrial wastewater treatment.