Novel ZnO/Zn–Cr hydrotalcite-like anionic clay as a high-performance and recyclable material for efficient photocatalytic removal of organic dye under simulated solar irradiation

Abstract

Reusable ZnO/Zn–Cr hydrotalcite-like anionic clays (ZnO/Zn–Cr HACs) were synthesized by a co-precipitation method and characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption–desorption analysis, elemental mapping patterns, scanning electronic microscope, and UV–Vis diffuse reflectance spectra. Its adsorption and photocatalytic activity towards organic pollutant (congo red as a model pollutant) were evaluated. The Langmuir isotherm was used to fit the equilibrium experiments. Saturated adsorption capacity of ZnO/Zn–Cr HACs was 426.29 mg g−1 at 308 K. The model pollutant exhibited fast and highly efficient removal from aqueous solution by ZnO/Zn–Cr HACs under simulated solar light irradiation. The experiments of cycles demonstrated that there was no evident change in the removal efficiency of Congo red (CR) solution by ZnO/Zn–Cr HACs the fifth time under simulated solar light irradiation, which indicates that ZnO/Zn–Cr HACs can be reused and will be favorable for effective elimination of toxic organic compounds in wastewater. Therefore, it is expected that ZnO/Zn–Cr HACs with layered structures and high surface areas can be potentially used as effective and reusable materials for large-scale environmental purification.