Effective phosphate removal from sewage water using zerovalent iron nanomaterial as an adsorbent

In recent times, nano zerovalent iron (nZVI) particles have attracted significant attention from researchers for their effectiveness in removing phosphates, a hazardous contaminant found in groundwater and surface water. nZVI possesses some excellent characteristics such as high reactivity, high surface area, and effective surface-to-volume ratio. In this study, nZVI was characterized by X-ray diffraction, Brunauer-Emmett-Teller (BET) surface area analyzer, Fourier transform infra-red (FT-IR), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. The effect of variations in nZVI dosage, pH, ionic strength, and coexisting anions on the removal of phosphate from laboratory-based synthetic water was explored. A maximum phosphate removal efficiency of 96% was achieved at an initial phosphate concentration of 25 mg/L, an nZVI dosage of 560 mg/L, and a shaking rate of 500 rpm, and pH 2 was attained within 120 min. Kinetic and equilibrium studies revealed that the adsorption of phosphate follows a pseudo-2nd-order kinetic model and a Temkin isotherm model, respectively. A thermodynamic study confirmed that phosphate adsorption is a spontaneous and endothermic process. Finally, nZVI was proved to be stable up to five cycles. nZVI was further applied for the removal of phosphate from sewage water, which was collected from Saheb bandh, Purulia district of West Bengal, Eastern India.