Investigation of sorbents synthesised by mechanical–chemical reaction for sorption of As(III) and As(V) from aqueous medium

Efficiency of Fe₂O₃ and mixture of Fe₂O₃ and MnO₂ nanoparticles synthesised by mechanical–chemical reaction for inorganic As(III) and As(V) sorption was examined. Sorbents (Fe₂O₃ and mixture Fe₂O₃:MnO₂ = 3:1) synthesised by mechanical–chemical treatment in planetary ball mile with different milling times were tested by batch experiments. Experimental data were fitted both to Freundlich and Langmuir adsorption models. Efficiency of sorption was in good correlation with the time of milling in case of pure oxide. There were small differences in sorption between As(III) and As(V). In the case of mixture of oxides results were different. The best results were obtained by 30 min of milling. With prolonged milling, the sorption decreased to 3 h and after that increased again. These results were explained by phase transition. Sorption kinetics, influence of pH and the presence of other anions were examined for mixture of oxides with highest sorption capacity. The bioavailability of sorbed arsen was tested using modified Tessier procedure.