Fe/Mn – modified adsorbents to arsenic and antimony removal from contaminated water

Abstract

Natural solids such as aluminosilicates, metal oxides, lignin, biowaste belong to low-cost and environmentally friendly materials with favorable surface properties. Their adsorption selectivity in water primarily depends on the actual pH value to the zero point of charge (pHZPC) of the solid. The surface modification of cation-selective (aluminosilicates) or uncharged (biochar) sorbents with Fe/Mn ions can change the surface charge (pHZPC) causing a strong selectivity to anions. Three different aluminosilicates and two biomaterials were treated with Fe2+, Fe3+ and Mn2+ ions. The raw and modified sorbents were characterized by XRD, XRF, SEM, SBET, pHZPC, particle size and IR spectroscopy. The adsorption properties and selectivity of prepared sorbents were tested in solutions containing arsenate (AsV), arsenite (AsIII) and antimonate (SbV) ions . The mechanism and kinetic of surface-mediated processes relied on the structure of raw material, the applied treating method and water quality. The adsorption parameters were calculated by Langmuir and Freundlich adsorption models and by the formal kinetic models.