Preparation of chitosan based electrospun nanofiber membrane and its adsorptive removal of arsenate from aqueous solution

Abstract

In this study, chitosan based electrospun nanofiber membrane (CS-ENM) was prepared as adsorbent for arsenate removal from water. The physicochemical properties of CS-ENM was explored by SEM, TGA and BET analysis. Batch adsorption experiments were systematically carried out to evaluate its arsenate adsorption performance with different process parameters such as solution pH, initial As(V) concentration, contact time, ionic strength, presence of coexisting anions and natural organic matters. XPS was used to investigate the interaction of CS-ENM with arsenate during the adsorption. Results showed that CS-ENM was highly porous with a large specific surface area. Solution pH played a key role in As(V) adsorption onto CS-ENM, and higher adsorption capacity was obtained at lower pH. Kinetics study demonstrated the adsorption equilibrium was achieved within 0.5h indicating that As(V) uptake by CS-ENM was very fast, and the kinetics process was well fitted by the pseudo-second-order model (R2>0.99). The adsorption isotherm experimental data correlated well with Langmuir model, and the maximum adsorption capacity was found to be 30.8mg/g which was higher than most of the reported chitosan adsorbents. The ionic strength effect study indicated the adsorbed As(V) formed outer-sphere surface complexes with CS-ENM. The existence of CO32− and F− influenced insignificantly to the adsorption of As(V), however the presence of SO42−, PO43− and humid acid exhibited negative effects on the uptake of arsenate. XPS analysis suggested amine groups on the chitosan backbone were involved in the adsorption of As(V).