Arsenate and phosphate removal from water using Fe-sericite composite beads in batch and fixed-bed systems

Abstract

Natural sericite clay was modified with iron-oxide and then the modified sericite was encapsulated into beads by employing the ionic gelation method to obtain Fe-sericite composite beads. The materials were fully characterized by N-2 adsorption-desorption isotherm, SEM-EDX, XRD, FT-IR and XPS analyses. Batch experiments showed that the composite beads showed a high uptake of As(V) and phosphate within a wide range of pH and the maximum sorption capacity determined by Langmuir isotherm were found to be 5.780 and 4.446 mg/g for As(V) and phosphate, respectively. The sorption kinetic data indicate that at least 12 h of contact time is necessary to attain the sorption equilibrium and intra-particle diffusion plays a significant role in the sorption process. The presence of background electrolyte (NaNO3\) or other heavy metals ions could not significantly affect the uptake of As(V)/phosphate by Fe-sericite composite beads. Furthermore, a fixed-bed column experiment has demonstrated that Fe-sericite composite beads could remove As(V) and phosphate up to acceptable level with a high breakthrough volume even under dynamic conditions. XPS analysis results indicate the successful sorption of As(V)/phosphate and it is assumed that these two pollutants formed an inner sphere complexes with iron oxide present in the composite beads. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.