Mechanistic insights and management approaches in photocatalytic degradation of tetracycline antibiotic using zinc ferrite nanoparticles

Abstract

Zinc-doped Zn<inf>x</inf>Cd<inf>0.8-X</inf>Ba<inf>0.2</inf>Al<inf>0.2</inf>Fe<inf>1.8</inf>O<inf>4</inf>(X = 0, 0.2) spinel ferrite nanoparticles were synthesized via the sol–gel auto-combustion method and characterized by XRD, FTIR, SEM, EDX, BET, and UV–Vis spectroscopy. Zinc incorporation at x = 0.2 reduced the optical bandgap from 2.86 eV to 2.69 eV, increased BET surface area from 7.54 to 10.23 m²/g (35.6% enhancement), and decreased crystallite size from 22.26 to 18.82 nm. Under visible-light irradiation (100 W, 105 min), the zinc-doped catalyst achieved 98% tetracycline degradation compared to 50% for the undoped material. The catalyst demonstrated broad-spectrum activity with degradation efficiencies of 85, 77, 65, and 48% for Congo Red, Rhodamine B, 65% for Methylene Blue, and 48% for Methyl Orange, respectively. The addition of peroxymonosulfate, hydrogen peroxide, and persulfate resulted in complete tetracycline removal at 15, 30, and 45 min, respectively. Scavenger experiments identified hydroxyl radicals as the primary degradation species, contributing to 63% of the overall process. The catalyst maintained an 82% efficiency after five consecutive cycles. Optimal performance was achieved at pH 3 (complete degradation in 30 min) with an 80 mg catalyst dosage (complete removal in 45 min). Under natural sunlight, complete tetracycline degradation was achieved in 30 min, demonstrating superior performance compared with artificial light sources.