Surface adsorption of organoarsenic roxarsone and arsanilic acid on iron and aluminum oxides

► Aromatic arsenicals' adsorption to metal oxide is controlled by their arsenate functional group. ► Aromatic arsenicals' di-anionic form is identified as the main adsorptive species. ► Goethite adsorbs aromatic arsenicals more effectively than Al2O3. ► The adsorption reaction is favorable at neutral and acidic pH. ► Competing solutes phosphate and natural organic matter significantly affect the adsorption.