Removal of arsenic(V) from aqueous solution using industrial solid waste: Adsorption rates and equilibrium studies

Industrial solid wastes can be recycled as nonconventional adsorbents, if t hey are nontoxic, to reduce the cost of wastewater treatments. "Waste" Fe(I II)/Cr(III) hydroxide, generated electrolytically in the treatment of Cr(VI ) containing wastewaters in a fertilizer industry was used for the adsorpti on of arsenic(V) from aqueous solution. Parameters studied include arsenic( V) concentration, agitation time, adsorbent dosage, adsorbent particle size , temperature, and pH. The adsorption capacity was evaluated by using both Langmuir and Freundlich isotherm models. The adsorption followed a first-or der rate expression. Adsorption of As(V) was independent of the initial pH (3-10) of the aqueous solution. Temperature studies showed that the adsorpt ion process was endothermic in nature. Desorption of As(V) from spent adsor bent was also investigated using NaOH solutions.