A Kinetic Uptake Study of Roxarsone Using Cross-Linked Chitosan Beads

Abstract

The adsorptive behavior of chitosan bead materials with roxarsone (ROX) was studied using a fixed bed column and a one-pot setup to evaluate the kinetic and thermodynamic adsorption parameters. The role of variable surface chemical properties of chitosan beads on the adsorption properties with ROX was investigated using a dye-based method, contact angle measurements, powder X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The equilibrium uptake (qe; mg ROX/g sorbent) values are listed in ascending order: non-cross-linked chitosan bead (52.5 mg/g) < chitosan bead cross-linked with epichlorohydrin (89.1 mg/g) < chitosan bead cross-linked with glutaraldehyde (104 mg/g). The results agree with uptake values obtained using a fixed bed column, where cross-linked chitosan beads display relatively rapid ROX uptake (0.121 min–1) relative to that of the non-cross-linked chitosan bead (0.053 min–1). These observed trends can be understood according to the hydrophile–lipophile balance and pore structure properties of cross-linked chitosan beads. The column bed removal efficiency (65.2%) increased for chitosan beads cross-linked with glutaraldehyde as the packed bed adsorbent material.