Valorization of water hyacinth to biochar-supported copper-doped tungsten trioxide composite for enhanced adsorptive/photocatalytic degradation: Life cycle assessment, techno-economic, and toxicity prediction

Abstract

While the photodegradation of hazardous contaminants using biochar-based composites has recently been examined, further research should address the associated environmental sustainability, economic feasibility, and by-product toxicity. Therefore, this study presents copper-doped tungsten trioxide anchored onto water hyacinth biochar as an eco-friendly persulfate (PS) activator-composite for the adsorptive/photocatalytic decomposition of methylene blue (MB) under UV–Vis irradiation. The adsorption efficiency of MB dye was 26.92 ± 1.43 % using the water hyacinth biochar (BC). This removal efficiency was improved to 98.79 ± 0.25 % for the combined adsorption/photodegradation mechanism using the as-prepared composite. These enhanced dye removal efficiency and chemical oxygen demand reduction (88.21 ± 1.32 %) were attributed to the synergistic effects of copper ions and BC on PS activation, generating radical species responsible for contaminant detoxification. The proposed system also maintained removal efficiencies of 89.25 ± 1.78 % for tetracycline and 91.72 ± 1.19 % for methyl orange, demonstrating a partial photocatalytic oxidation of other organic compounds. This adsorptive/photocatalytic process was economically feasible, with an internal rate of return of 10 %, positive net present value, and a shorter payback period of 6.27 years. Sensitivity analysis demonstrated that the photocatalyst price was the main contributor responsible for achieving a financially profitable adsorptive/photodegradation process. A cradle-to-gate life cycle assessment approach showed minimum environmental burdens across the toxicity-related midpoint impact categories, which were also validated using a toxicity estimation software tool (i.e., releasing less-toxic degradation by-products). Future studies should assess the catalyst/PS/UV–Vis system's performance for mixed dye stuff degradation under solar radiation conditions, mitigating various environmental contaminants from the textile industries. PS is persulfate (PS) activator composite considered for the synthesize of copper-doped tungsten trioxide anchored on water hyacinth biochar (CuWBC), which is used for adsorptive/photocatalytic wastewater treatment Economic feasibility criteria are PP: payback period, IRR: internal rate of return, ROI: return on investment, and NPV: net present value LCA is life cycle assessment. • CuWBC/UV–Vis/PS composite exhibited excellent photodegradation of dye and tetracycline. • SO 4 •− , h + , • OH, and O 2 •− radical were involved in contaminant degradation and detoxification. • Intermediate byproducts had minimum developmental toxicants and bioconcentration factors. • Adsorptive/photocatalytic treatment achieved positive net present value; 6.3 yr payback period. • Environmental LCA showed improvement in human health and ecosystem impact categories.