Porous urchin-like 3D Co(ii)Co(iii) layered double hydroxides for high performance heterogeneous Fenton degradation

Abstract

Heterogeneous Fenton processes can overcome the generation of iron sludge and the production of more solid wastes. However, the performance of the catalyst is far from satisfactory, especially when wastewater has a pH > 3. To overcome these problems, porous urchin-like 3D Co(II)Co(III) layered double hydroxides (LDHs) were synthesized via a facile solvothermal process. The effect of various factors on the morphologies and formation mechanism was systematically investigated. The porous urchin-like 3D Co(II)–Co(III) LDH (CCLH 120) displayed the best catalytic activity for heterogeneous Fenton degradation by using 60 μL H₂O₂ and 0.1 g L⁻¹ catalyst over a wide range of pH. The high surface area, porosity and good dispersibility of the nanoparticles stimulated the rapid and massive generation of reactive oxygen species in the heterogeneous Fenton reaction. The degradation efficiency for different types of dyes was measured to be 97%, 95% and 77% for methylene blue, Rhodamine B and methyl orange, respectively. The degradation rate of RhB is found to be 5.41 × 10⁻⁵ mol g⁻¹ s⁻¹. When applied in the treatment process of mining wastewater, the chemical oxygen demand (COD) values can efficiently be reduced from 817 mg L⁻¹ to 30 mg L⁻¹, which clearly indicates that the material has good potential as a high performance catalyst in Fenton reactions for treating industrial effluents.