International Journal of Science and Technology (IJST)

Efficiency of Magadiitic Aluminosilicate Nanozeolites for the Removal of Nitrate (NO₃⁻) and Phosphate (PO₄³⁻) Agro-pollutants from Aqueous Solutions

The aim of this study was to determine the efficiency of the Magadiitic aluminosilicate nanozeolites in the removal of the agro-pollutants nitrate (NO₃⁻) and phosphate (PO₄³⁻) from aqueous solutions. The findings demonstrated that the optimized nanozeolite exhibited exceptional efficiency and high selectivity for (PO₄³⁻) ions, achieving removal efficiencies up to or exceeding 99.9 % in optimized specific condition across analysed concentrations ranging from 5 mg/L - 50 mg/L and maintaining nearly perfect removal of 99.999 % across the stable pH range of 2–6. This robust performance for phosphate was linked to strong chemisorption mechanisms, such as ligand exchange and inner-sphere complexation, characterized by a highly spontaneous, ΔGo = -20.37 kJ/mol at 25 °C and entropy-driven thermodynamic profile, and yielding a maximum adsorption capacity (qm) of up to 2,736 mg/g. In stark contrast, nitrate removal efficiency was significantly lower and less consistent, ranging between 65.88 % and 71.6 % across concentration changes, and was highly sensitive to increases in pH above 6 and temperature changes above 35 °C. Nitrate adsorption was predominantly confirmed as a physisorption-driven process supported by weaker electrostatic attractions, indicated by a low mean adsorption energy (E) of 3.45 kJ/mol and a less spontaneous nature, ΔGo = - 6.11 kJ/mol at 25 °C. However, the adsorption kinetics for both anions were best fitted by the Pseudo-Second-Order model, which unequivocally confirmed chemisorption as the overall primary mechanism. Keywords: Agro-pollutants, Magadiitic aluminosilicate nanozeolite, chemisorption, nitrates, phosphates, physisorption