Biochar-Supported FeS/Fe3O4 Composite for Catalyzed Fenton-Type Degradation of Ciprofloxacin

Yue Wang,Dongqing Feng,Anthony K Hodge,Liujiang Hu,Xiaoxiao Zhu,Jianfa Li,Jinhong Lü

doi:10.3390/catal9121062

Abstract

The Fenton-type oxidation catalyzed by iron minerals is a cost-efficient and environment-friendly technology for the degradation of organic pollutants in water, but their catalytic activity needs to be enhanced. In this work, a novel biochar-supported composite containing both iron sulfide and iron oxide was prepared, and used for catalytic degradation of the antibiotic ciprofloxacin through Fenton-type reactions. Dispersion of FeS/Fe3O4 nanoparticles was observed with scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). Formation of ferrous sulfide (FeS) and magnetite (Fe3O4) in the composite was validated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Ciprofloxacin (initial concentration = 20 mg/L) was completely degraded within 45 min in the system catalyzed by this biochar-supported magnetic composite at a dosage of 1.0 g/L. Hydroxyl radicals (·OH) were proved to be the major reactive species contributing to the degradation reaction. The biochar increased the production of ·OH, but decreased the consumption of H2O2, and helped transform Fe3+ into Fe2+, according to the comparison studies using the unsupported FeS/Fe3O4 as the catalyst. All the three biochars prepared by pyrolysis at different temperatures (400, 500 and 600 °C) were capable for enhancing the reactivity of the iron compound catalyst.

Highlights

Biochar is a kind of carbonaceous material obtained by pyrolysis of biomass feedstock, such as wood processing residues and agricultural wastes
Dispersion of ferrous sulfide (FeS)/Fe3 O4 particles on the biochar can be found in the biochar-supported composite (FeS/Fe3 O4 @BC500), according to that shown in Figure 1c,d, as most of the iron compound particles in the supported composite have a size of
FeS was synthesized first and formed the inner core of the composite, while Fe3O4 deposited itself on the outer surface of these composite particles, accompanying with partial exposure of FeS

Summary

Introduction

Biochar is a kind of carbonaceous material obtained by pyrolysis of biomass feedstock, such as wood processing residues and agricultural wastes. Due to its low cost, high surface area and good stability, biochar is a promising supporting material comparable with other carbons [7,8], and has been applied to enhance the performance of iron or iron minerals in environmental remediation. The biochar can disperse the zero-valent iron nanoparticles and prevent their aggregation, so that the removal efficiency of heavy metals (e.g., Cr(VI). The biochar-supported nanoscale zero-valent iron has shown to be an efficient catalyst for the Fenton-type oxidation of organic pollutants, such as trichloroethylene [11,12], bisphenol A [13], sulfamethazine [14] and ciprofloxacin [15]

Methods

Results

Conclusion