A cost-effective catalytically adsorbent for in situ remediation of manganese contaminated groundwater

Abstract

Abstract Manganese oxide coated scoria (MOCS) was prepared as a cost-effective catalytically adsorbent with high permeability to remediate manganese contaminated groundwater. Scanning electron microscope visual expressed that on the relatively smooth surface of raw scoria (RS) a large amount of micro pores and dense bulk-like structures after modification and filtration appeared. The data from Fourier transform infrared showed that the intrinsic scoria structure was unchanged during modification. The X-ray diffraction and X-ray photoelectron spectroscopy instrumental studies revealed that the newborn manganese oxide layer was a mixed-valence of manganese (Mn3+ and Mn4+) which could absorb the Mn2+ and catalytically facilitate oxidation with oxygen. Subsequently, the adsorption capacity of RS and MOCS was demonstrated in adsorption experiments. The kinetics of manganese adsorption by RS and MOCS followed pseudo-second-order with the correlation coefficients of 0.983 and 0.989, respectively. The experimental data were better fitted to Langmuir isotherm than Freundlich isotherm, indicating that the monolayer adsorption process for manganese was acting on the surface of RS and MOCS. The filtration experiment showed high Mn2+ removal efficiency by MOCS in a wide range of hydraulic retention time (15–40 min) in 40 days, which demonstrated that the MOCS is a good potential application prospect for manganese removal from groundwater.