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

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.