Effective heterogeneous Fenton-like degradation of antibiotics by ferroferric oxide nanoparticle coated reduced iron powder with accelerated Fe(ii)/Fe(iii) redox cycling

Abstract

Heterogeneous Fenton-like processes based on Fe-based catalysts are effective technology to degrade emerging organic pollutants in water and wastewater such as tetracycline (TC). However, the kinetically limited redox cycling between Fe²⁺ and Fe³⁺ is still a persistent challenge for their widespread application. To address this issue, we designed a novel Fe-based catalyst by coating reduced iron powder (RIP) with ferroferric oxide nanoparticles (FONP@RIP) using a simple chemical co-precipitation method. The reduced iron could rapidly reduce Fe(III) to Fe(II) and accelerate the cycle of Fe(II)/Fe(III) in the heterogeneous Fenton-like system. Benefiting from the accelerated cycle of Fe(II)/Fe(III), TC could be efficiently degraded in the FONP@RIP/H₂O₂ system over a wide pH range of 3–6, with a removal efficiency of 94.5% within 60 min (TC₀ = 150 ppm). The predominant reactive oxygen species were identified as ˙OH and HO₂˙. Based on the identified intermediates, the possible pathway of TC degradation was deduced and the toxicity of pollutants could also be significantly reduced during the degradation process. Moreover, FONP@RIP exhibited stable catalytic performance during multiple cyclic tests with only a marginal loss of catalytic components. This study presents a new catalyst design strategy for heterogeneous Fenton-like processes, which provides a promising way for the degradation of residual antibiotics in water and wastewater.