Adsorption of As(V) on aluminum-, iron-, and manganese-(oxyhydr)oxides: equilibrium and kinetics

In the present work, three metal ( oxyhydr) oxides, i. e. 2-line ferrihydrite (FeOOH), bayerite ( beta- Al( OH) 3), and hausmannite ( Mn3O4), were prepared and then employed as adsorbents for As( V) in aqueous solution. Both adsorption equilibrium and kinetics of As( V) have been investigated via batch experiments. The adsorption equilibrium results indicated that all adsorption data follow the Langmuir equation with maximum adsorption capacities of 28.57, 14.29, and 1.00 mg g (-1) for FeOOH, beta- Al( OH) 3, and Mn3O4, respectively. It was found that the pseudo-second- order kinetic equation is capable of fitting these kinetic data well with correlation coefficients ( R2) greater than 0.98. The effects of co-occurring anions, both phosphate ( PO3 (4)) and sulfate ( SO42), were shown to reduce As( V) uptake, whereas calcium ion ( Ca (2+)) was found to enhance As( V) adsorption. This work can extend our understanding of equilibrium and kinetic behaviors of As( V) adsorption on typical metal ( oxyhydr) oxides.