Design and Implementation of a Heterogeneous Magnetic Quaternary Composite for Efficient Arsenic(V) Removal in Polluted Water

This work highlights a potential quaternary composite adsorbent (CT: γ-Fe₂O₃-TiO₂-GO-zeolite 5A) to remove As(V) from contaminated water. The CT was characterized by various analytical techniques before and after the adsorption experiments. Contact time, pH, and adsorbent dose were evaluated. The results indicated a removal greater than 94% in a contact time of 3 h at a pH of 6.5. The data on adsorption kinetics agree with the pseudo-second-order model; while the adsorption isotherms coincide with Sips model, which suggests that the adsorption of As in the CT composite is carried out through chemisorption. In addition, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) revealed the deformation of the CT structure. X-ray diffraction (XRD) showed the reduction of zeolite 5A crystallite size from 76.1 to 28.3 nm, of γ-Fe₂O₃ from 15.3 to 7.7 nm, while that of anatase remained unchanged. The magnetic analysis confirmed that the composite has response to magnetic handling still after adsorption, as necessary for its separation. Based on the X-ray photoelectron spectroscopy (XPS) results, γ-Fe₂O₃ and Z5A are proposed as compounds of major participation in As adsorption, through weak electrostatic interaction and complex formation, respectively. In addition, GO contributes hydroxyl groups reducing the repulsion by the negative As species. Thus, this composite presents remarkable characteristics as an alternative for remediation of water contaminated with As.