Adsorption of ammonia nitrogen in wastewater by tailing loaded manganese oxide material

Abstract

In this study, manganese oxide (MnOx) was loaded onto tailing (TA) containing layered silicate minerals by redox precipitation, and its adsorption performance of ammonia nitrogen was investigated. In the experiments, the effects of TA loaded with different manganese oxide content ([email protected]), initial pH of adsorption, and coexisting ions (Ca2+, K+, and Na+) on adsorption were analysed, and then kinetic fitting and adsorption isotherm fitting were performed. Meanwhile, several methods were used to characterize the material, including scanning electron microscope (SEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Zeta potential. The results showed that the adsorption can be promoted by the increase of MnOx content and the adjustment of pH between 6 and 8, however, coexisting ions inhibit the adsorption of ammonia nitrogen, and the inhibition strength is Ca2+ > K+ > Na+ at the same concentration. The adsorption process conformed to the pseudo-second-order kinetic model and Langmuir adsorption isotherm. The saturated adsorption capacity of [email protected] was 18.21 mg/g, which was much higher than that of the TA (5.61 mg/g). Several characterization methods confirmed the successful loading of MnOx, and the adsorption mechanism included electrostatic adsorption of hydroxyl and NH4+, ion exchange adsorption, and redox reaction. This study can lay an important foundation for mines to use TA to treat ammonia nitrogen wastewater and realize the treatment of waste can be used with other waste.