Arsenate Removal from the Groundwater Employing Maghemite Nanoparticles

Abstract

An investigation of the potential of γ-Fe2O3 (maghemite) nanoparticles (MNPs) to remove AsV from groundwater is reported. The MNPs were synthesized using a modified co-precipitation method via refluxing. The morphological and surface characteristics of MNPs were analyzed using XRD, FTIR, SEM, TEM, and Zetasizer techniques. Their AsV removal potential was explored in synthetic water representing the elemental composition equivalent to arsenic-contaminated groundwater of the Ballia district, Uttar Pradesh, India. The arsenic concentration in the samples collected from the study area was observed to be much more than the provisional WHO guideline value for drinking water (10 µg L−1). An orthogonal array L27 (313) of the Taguchi design of experimental methodology was employed to design the experiments and optimization of AsV removal. The ANN tool was trained to evaluate Taguchi’s outcomes using MATLAB. The percentage of ionic species distribution and surface complexation modeling was performed using Visual MINTEQ. The study explored the effects of pH, temperature, contact time, adsorbent dose, total dissolved solids, and shaking speed on the removal process. The adsorption was found to occur through electrostatic interactions. The inter-parametric analysis demonstrated the involvement of secondary sites affecting the adsorption. The charge distribution multi-sites complexation (CD-MUSIC) model and 2pk-Three-Plane-Model (TPM) indicated the involvement of the reactivity of singlet (FeOH−0.5) and triplet (Fe3O−0.5) species in the examined pH range. The developed nanoparticles are observed to be efficient in AsV removal. This information could benefit field-scale arsenic removal units.