Removal of chromium(VI) from aqueous solution using iron orthophosphate that is synthesized by different methods

The adsorption of chromium(VI) from aqueous solutions was studied on iron orthophosphate synthesized by solution, solution combustion, and solid state method. The properties of samples were determined by X-ray powder diffraction, nitrogen adsorption, and scanning electron microscope. The adsorption of chromium(VI) on solution combustion synthesized iron orthophosphate was found to be maximum in comparison to the other synthesis approaches. The equilibrium data for the adsorption of chromium were analyzed in Langmuir and Freundlich isotherm models. The adsorption process could be described by pseudo-second-order kinetic model. Iron orthophosphate was the most active at pH 2. The maximum adsorption capacity for iron orthophosphate synthesized by solution combustion, solid state, and solution method are 21, 13.2, and 12.1 mg/g at 100 ppm chromium concentration with 1 g/L adsorbent dose for 2 h. Iron orthophosphate is cheap and easy to operate for adsorption of hexavalent chromium(VI) from wastewater.