Preparation of Fe-Mn layered double hydroxides and its adsorption behavior of antimony (III) from wastewater

In order to solve the problem of antimony (Ⅲ) pollution in water environment, Fe-Mn layered double hydroxides (Fe-Mn LDH) were prepared by ultrasonic co-precipitation method, and the effects of initial pH, dosage, coexisting ions, adsorption time and temperature on the removal of antimony (Ⅲ) from wastewater by Fe-Mn LDH were studied. The crystal structure, morphology and adsorption mechanism were characterized and analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The results show that the suitable conditions for antimony (Ⅲ) removal are: pH of 5, dosage of 0.4 g/L and adsorption time of 150 min under 45℃; Under these conditions, the maximum adsorption capacity is 77.39 mg/g. The adsorption process conforms to the pseudo-second-order kinetic model, and the Freundich isotherm model can well describe the adsorption behavior of antimony(Ⅲ). The adsorption mechanisms of antimony (Ⅲ) mainly include ion exchange, coordination complex and electrostatic interaction. The removal efficiency of antimony (Ⅲ) is found to be over 83.03% by four adsorption-desorption experiments. This study indicates that Fe-Mn LDH has the potential to treat and repair wastewater containing antimony (Ⅲ).