Effect of Ni2+ loading on the mechanism of phosphate anion sorption by iron hydroxide

Phosphate sorption on pure and Ni-loaded iron hydroxide was studied as a function of pH (3–7), and temperature (293–323 K). The sorption was observed to increase in both the solid samples with concentration and temperature of the system and decrease with the increase in pH. Further it was observed that nickel ion loading led to an increase in surface area and PZC, which resulted in an increased uptake of the phosphate anions. Freundlich equation was successfully applied to the sorption data. Thermodynamics parameters such as ΔG°, ΔH° and ΔS° for Ni-loaded solid were estimated from constants of Freundlich equation. FTIR spectrometry after phosphate sorption showed the formation of inner sphere complexes on both the pure and Ni2+-loaded iron hydroxides.