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 independently evaluates and compares two distinct remediation pathways—visible-light-driven photocatalysis using silver zirconate (Ag₂ZrO₃) nanomaterial and biodegradation via Pseudomonas aeruginosa ATCC14886 for efficient H-acid 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 pseudo-first-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 degradation within 24 h through a catechol-mediated aromatic cleavage pathway. Application to real industrial effluent yielded substantial reductions in COD (96.7%), BOD (77.8%), and TDS (87.5%), with HPLC confirming near-complete pollutant removal. Overall, this comparative assessment demonstrates that silver zirconate-driven advanced oxidation offers rapid and efficient H-acid degradation, while microbial treatment, though slower (24 h), offers a sustainable and eco-compatible alternative with the added advantage of biofertilizer benefits. These approaches highlight practical guidance for rational selection of suitable treatment strategies for the remediation of recalcitrant H-acid dye intermediates in industrial wastewater.