Decontamination of methylene blue from aqueous solution by magnetic chitosan lignosulfonate grafted with graphene oxide: Effects of environmental conditions and surfactant

Abstract

In this study, magnetic chitosan lignosulfonate grafted with graphene oxide (MCLS/GO) as an innovative adsorbent was prepared successfully through a hydrothermal reaction. The adsorbent was also characterized using SEM, XRD, VSM, FTIR, XPS, and zeta-potential. The effects of pH, ionic strength, temperature and SDBS (sodium dodecylbenzene sulfonate) on the adsorption behavior of MB (methylene blue) by the MCLS/GO were investigated. The results indicate that MB removal is found to be more effective at a higher pH value and temperature. The adsorption process could be affected by ionic strength, particularly at a higher concentration. Isotherm and kinetics were well-fitted by a Langmuir isotherm model and pseudo-second-order model, respectively. In addition, the presence of SDBS had a positive effect on MB adsorption onto MCLS/GO. An intra-particle diffusion model indicates that both film diffusion and intra-particle diffusion were the rate-controlling processes. Thermodynamic analysis showed that the adsorption reaction was an endothermic and spontaneous process. The adsorption mechanism was proposed to be electrostatic attraction, π-π stacking interaction and hydrogen bonding via FTIR analysis. In conclusion, this study implies that MCLS/GO nanoparticles could be conveniently separated from a water body by an external magnet and utilized as an efficient adsorbent for environment purification.