Preliminary mechanisms for arsenic removal by natural ferruginous manganese ore

Understanding of the mechanisms for arsenic removal by natural ferruginous manganese ore is of great significance for the development of safe, efficient techniques for arsenic remediation. Characterisation of natural ferruginous manganese ore was carried out using X-ray fluorescence spectrometry analyses. The mechanisms were intensively explored under Fourier-transform infrared spectroscopic analysis, and zeta potential analysis (pHPZC). The results indicate that natural ferruginous manganese ore primarily contained Mn, Fe, Si and Al, etc., with abundant hydroxyl radical [center dot OH] on the surface of ore, which resulted in good arsenic adsorptive capabilities. The removal efficiency of As(III) and As(V) by adsorption onto the ore was up to 95.57% and 92.89%, respectively, under the conditions of ratio of solution/ore of 500, a reaction time of 1 hour, and As concentration of 0.200 mg L-1. The adsorption process followed the second-order rate law. Instrumental analysis indicated that efficient arsenic removal onto natural ferruginous manganese ore was due to the combination of the oxidation of manganese, complexation of ferric hydroxide and the adsorption of center dot OH on the manganese ore.