Study on the preparation of Nano-Fe3O4 by steel pickling waste liquor and its effective removal of Cr (VI) from wastewater

Abstract

In order to comprehensively treat and utilize steel pickling waste liquor (SPWL), this study used SPWL as raw material to prepare two different crystalline forms of Nano-Fe3O4 by co-precipitation and precipitation-oxidation methods, and investigated their removal effect on Cr(VI) in wastewater. The two kinds of Nano-Fe3O4 were characterized using SEM, XRD, and VSM, and the results showed that the Nano-Fe3O4 synthesized by the co-precipitation method has better properties. The two kinds of Nano-Fe3O4 were used to remove Cr(VI) in wastewater, the adsorption capacity could reach 38.38 mg/g and 15.83 mg/g, respectively. Five adsorption kinetic models and five isothermal adsorption models were used to study the adsorption mechanism of Fe3O4 on Cr(VI). The adsorption process of Cr(VI) by Nano-Fe3O4 was explained well using the pseudo-second-order and Freundlich isotherm model, and the results showed that the adsorption process mainly involved physical and chemical adsorption. Through the characterization analysis before and after the reaction, the removal mechanism of Cr(VI) by Nano-Fe3O4 prepared from SPWL is mainly attributed to electrostatic adsorption and reduction reaction. According to the market survey and analysis, the production cost is reduced by at least 58.33 % compared to that of Nano-Fe3O4 prepared using analytical purity in the market. Therefore, the preparation of Nano-Fe3O4 by steel pickling waste liquor provides an economical and effective way to remove heavy metal ions in wastewater.