Phosphorus adsorption onto green synthesized nano-bimetal ferrites: Equilibrium, kinetic and thermodynamic investigation

Phosphorus (P) in natural aquatic environments is one of the most critical elements for causing eutrophication. On the other hand, it is also an essential nutrient for organisms in broad ecosystems. Therefore, it has become an important issue in environmental and ecological sciences to remove and recover efficiently of P in various water bodies. This study investigates the feasibility of P removal/recovery using nano-bimetal ferrites (CuFe2O4), manufactured from industrial sludge. These new results reveal that a rapid P removal, from 9.9% to 99.9%, was observed when the solution pH decreased from 9.06 to 2.64. The maxima P adsorption capacity was found to be 13.5 mg g−1 at pH 2.64 (318 K), which is much higher than other available adsorbents. The observed negative changes in the standard free energy (ΔG  = −4.99, −5.47, −6.12, −7.21 kJ mol−1 at 288, 298, 308, and 318 K, respectively) and the positive value of ΔH (1.92 kJ mol−1) demonstrate that the adsorption reaction is spontaneous and endothermic. Moreover, we observed also that the P adsorption increases with the increased of ionic strength from 0.001 to 1.0 N, suggesting important involvement of some inner-sphere mechanisms.