Efficient Removal of H-Acid from Industrial Wastewater via Ag₂ZrO₃ Nanocatalyst-Mediated Advanced Oxidation and Pseudomonas aeruginosa Biodegradation

Abstract

H-acid (1-amino-8-naphthol-3,6-disulfonic acid), a recalcitrant azo dye intermediate, is a major contributor to industrial wastewater pollution. This study evaluates two independent treatment pathways-visible-light-driven photocatalysis using silver zirconate (Ag₂ZrO₃) nanomaterial and biodegradation via Pseudomonas aeruginosa ATCC14886 for efficient Hacid removal. Ag₂ZrO₃ was synthesised via chemical precipitation and characterised by PXRD, UV-DRS, FESEM, TEM, EDS, XPS, and BET analyses. Photocatalytic activity was enhanced with peroxymonosulfate (PMS) and hydrogen peroxide (H₂O₂), achieving excellent degradation efficiencies of 99.87% (PMS) and 99.5% (H₂O₂) within just 90 min, with pseudofirst-order rate constants of 5.04 × 10⁻ 2 min⁻ 1 and 6.38 × 10⁻ 2 min⁻¹ for PMS and H₂O₂-assisted systems, respectively. Radical scavenging confirmed hydroxyl radicals (•OH) as the dominant oxidative species in both systems. Microbial degradation achieved complete mineralisation within 24 h through a catechol-mediated aromatic cleavage pathway. Application to real industrial effluent yielded substantial reductions in COD (97.4%), BOD (77.8%), and TDS (87.5%), with HPLC confirming near-complete pollutants removal. These findings demonstrate that silver zirconate-driven advanced oxidation offers a rapid and efficient H-acid degradation, while microbial treatment though slower (24 h), offers a sustainable alternative with added advantage of biofertilizer benefits. Overall, these approaches highlight promising eco-compatible strategies for the remediation of recalcitrant H-acid dye intermediates in industrial wastewater..