Synthesis of Highly Monodispersed, Stable, and Spherical NZVI of 20-30 nm on Filter Paper for the Removal of Phosphate from Wastewater: Batch and Column Study

A nanobiodegradable adsorbent was prepared by stabilizing nanoscale zerovalent iron (NZVI) on cellulose filter paper. Characterization of the sample disclosed that the NZVI particles were rounded, well-monodispersed through the paper, and smaller than 30 nm in diameter. We explored this material's ability to capture phosphate ions in batch and repeated operations, specifically studying the impact of pH, adsorption time, initial phosphate concentration, interference ions, and temperature. The equilibrium results were matched to dissimilar kinds of adsorption isotherms, with the Sips adsorption model displaying the best match. The stabilized NZVI indicated high reusability after 7 adsorption-desorption cycles. We also demonstrated how this nanobiodegradable adsorbent could be applied to eliminate phosphate ions from a real water source (Cayuga Lake). In the continuous system, the results confirmed that an enhancement in the initial phosphate ion concentration improved the phosphate removal ability of the filter-paper-stabilized NZVI, likely due to more motive power for mass transfer by the greater phosphate concentration. However, an enhancement in bed height and flow rate reduced phosphate removal because of the higher flow rate decreasing the reaction time of the solution and adsorbent, whereas the higher bed height resulted in a channeling effect. Breakthrough curves gained from fixed-bed column tests showed the strong potential of the NZVI for phosphate ion sequestration. An artificial neural network model was used to envision the phosphate ions removal in both batch and continuous systems by this composite. The adsorption mechanism of phosphate onto the filter-paper-stabilized NZVI was further investigated by X-ray spectroscopy, X-ray diffraction, elemental mapping, and zeta potential techniques.