# Synthesis, characterization, and performance of the Fe-HApBio heterogeneous catalyst for electro-Fenton degradation of cefuroxime sodium

## TL;DR

A new catalyst made from iron-doped hydroxyapatite efficiently breaks down the antibiotic cefuroxime sodium using electro-Fenton technology, with high stability and environmental benefits.

## Contribution

A novel Fe-HApBio catalyst derived from bio-waste is developed for efficient and sustainable electro-Fenton degradation of antibiotics.

## Key findings

- Fe-HApBio achieved total degradation of cefuroxime sodium in 25 minutes and near-complete mineralization after 5 hours.
- Hydroxyl radicals were identified as the primary oxidizing species in the degradation process.
- The catalyst remained stable after multiple reuse cycles and enhanced biodegradability for low-cost biological post-treatment.

## Abstract

An efficient heterogeneous Electro-Fenton (EF) process was developed using a catalyst based on hydroxyapatite derived from bovine bone bio-waste (HApBio), doped with iron through ion exchange (Fe(x)-HApBio), for the degradation and mineralization of the antibiotic Cefuroxime Sodium (CFX-Na) in an aqueous medium. The materials were synthesized and characterized by different techniques including X-ray diffraction (XRD), Fourier transform infrared absorption spectroscopy (FTIR), scanning electron microscopy coupled with EDX (SEM-EDX) and X-ray fluorescence spectroscopy (XRF). These analyses demonstrated the high structural stability of HApBio despite iron doping, a homogeneous dispersion of iron, the presence of functional groups characteristic of hydroxyapatite such as hydroxyl ions OH−, H2O, PO43−, and CO32−, as well as a total iron content of 5.687 wt%. The catalytic activity of the catalyst was evaluated without any prior adjustment to the pH of the solutions. The results showed that an optimal doped iron content of 0.5%, with a catalyst concentration of 1 g L−1 applying a current of 400 mA, allowed total degradation to be achieved in 25 min and almost complete mineralization after 5 hours of electrolysis. Radical scavenging experiments using DMSO and chloroform confirmed that hydroxyl radicals (˙OH) were the primary oxidizing species, while hydroperoxyl (˙O2H) and superoxide (O2˙−) radicals were also present in the degradation process. To describe the formation pathways of these reactive species a reaction mechanism was proposed. Also, the catalyst demonstrated good stability after several reuse cycles. Moreover, heterogeneous EF treatment enhanced the biodegradability of the solution after 90 minutes, and therefore, allowed its subsequent low-cost biological treatment. After 17 days, aerobic biological post-treatment achieved almost complete mineralization, which indicated the overall efficiency, sustainability, and less energy consumption of the process.

Fe(iii)-doped bio-hydroxyapatite efficiently degrades cefuroxime via electro-Fenton, dominated by ˙OH radicals. The catalyst is stable and reusable, and coupling electro-Fenton with aerobic biotreatment achieves near-complete mineralization.