Removal of Arsenic from Wastewater by Using Nano Fe3O4/Zinc Organic Frameworks
Xuexia Huang, Yun Liu, Xinyi Wang, Linwei Zeng, Tangfu Xiao, Dinggui Luo, Jia Jiang, Hongguo Zhang, Yuhui Huang, Mingzhen Ye, Lei Huang
Abstract
Efficient removal of arsenic in wastewater is of fundamental importance due to the increasingly severe arsenic pollution. In this study, a new composite adsorbent (Fe3O4@ZIF-8) for As(V) removal from wastewater was synthesized by encapsulating magnetic Fe3O4 nanoparticles into metal organic frameworks. In order to evaluate the feasibility of Fe3O4@ZIF-8 as an adsorbent for As(V) removal, the adsorption properties of Fe3O4@ZIF-8 were systematically explored by studying the effects of dosage, pH, adsorption isotherm, kinetics, and thermodynamics. Additionally, the characterization of Fe3O4@ZIF-8 before and after adsorption was analyzed thoroughly using various tests including SEM-EDS, XPS, BET, XRD, TG, FTIR, and the properties and arsenic removal mechanism of the Fe3O4@ZIF-8 were further studied. The results showed that the Fe3O4@ZIF-8 has a specific surface area of 316 m2/g and has excellent adsorption performance. At 25 °C, the initial concentration of arsenic was 46.916 mg/L, and pH 3 was the optimum condition for the Fe3O4@ZIF-8 to adsorb arsenic. When the dosage of the Fe3O4@ZIF-8 was 0.60 g/L, the adsorption of arsenic by the Fe3O4@ZIF-8 can reach 76 mg/g, and the removal rate can reach 97.20%. The adsorption process of arsenic to the Fe3O4@ZIF-8 can be well described by the Langmuir isotherm model and the second-order kinetic equation. At pH 3 and temperature 298 K, the maximum adsorption capacity of arsenic by the Fe3O4@ZIF-8 was 116.114 mg/g. Through the analysis of thermodynamic parameters, it is proved that the adsorption process of arsenic by the Fe3O4@ZIF-8 is a spontaneous endothermic reaction. The Fe3O4@ZIF-8 has broad prospects for removing As(V) pollution in wastewater, because of its strong adsorption capacity, good water stability, and easy preparation.