# Efficient Tetracycline Hydrochloride Degradation by Urchin-Like Structured MoS2@CoFe2O4 Derived from Steel Pickling Sludge via Peroxymonosulfate Activation

## TL;DR

A catalyst made from steel pickling sludge efficiently degrades tetracycline hydrochloride using peroxymonosulfate activation.

## Contribution

A cost-effective method to convert steel pickling sludge into a high-performance Fe-based catalyst for tetracycline hydrochloride degradation.

## Key findings

- The MoS2@CoFe2O4 catalyst achieved 81% tetracycline hydrochloride degradation within 30 minutes.
- SO4∙− was identified as the primary oxidative species in the degradation process.
- The catalyst showed high stability and reusability across multiple cycles.

## Abstract

Steel pickling sludge serves as a valuable iron source for synthesizing Fe-based catalysts in heterogeneous advanced oxidation processes (AOPs). Here, MoS2@CoFe2O4 catalyst derived from steel pickling sludge was prepared via a facile solvothermal approach and utilized to activate peroxymonosulfate (PMS) for tetracycline hydrochloride (TCH) degradation. Comprehensive characterization using scanning electron microscopy (SEM)-energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) confirmed the supported microstructure, composition, and crystalline structure of the catalyst. Key operational parameters—including catalyst dosage, PMS concentration, and initial solution pH—were systematically optimized, achieving 81% degradation efficiency within 30 min. Quenching experiments and electron paramagnetic resonance (EPR) analysis revealed SO4∙− as the primary oxidative species, while the catalyst maintained high stability and reusability across cycles. TCH degradation primarily occurs through hydroxylation, decarbonylation, ring-opening, and oxidation reactions. This study presents a cost-effective strategy for transforming steel pickling sludge into a high-performance Fe-based catalyst, demonstrating its potential for practical AOP applications.