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 they are nontoxic, to reduce the cost of wastewater treatments. “Waste” Fe(III)/Cr(III) hydroxide, generated electrolytically in the treatment of Cr(VI) containing wastewaters in a fertilizer industry was used for the adsorption 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-order rate expression. Adsorption of As(V) was independent of the initial pH (3−10) of the aqueous solution. Temperature studies showed that the adsorption process was endothermic in nature. Desorption of As(V) from spent adsorbent was also investigated using NaOH solutions.