Efficient adsorption of rhodamine B using synthesized Mg–Al hydrotalcite/ sodium carboxymethylcellulose/ sodium alginate hydrogel spheres: Performance and mechanistic analysis
Siqi Chang, Xiangling Zhang, Chen Wang, Jing Bai, Xuhao Li, Wei Liang, Yajia Mao, Jixian Cai, Yifan Li, Yu Jiang, Zhouying Xu
Abstract
In this study, the sodium dodecyl sulfate intercalated modified magnesium-aluminum hydrotalcite/sodium alginate/sodium carboxymethylcellulose (modified LDHs/SA/CMC) composite gel spheres were synthesized and their efficacies in adsorbing the cationic dye rhodamine B (RhB) from aqueous solutions were evaluated. The effects of adsorption time, pH and temperature on the adsorption of RhB by spheres were investigated. Remarkably, the modified LDHs/SA/CMC gel spheres achieved adsorption equilibrium after 600 min at 25 °C, and the removal rate of RhB at 60 mg/L reached 91.49 % with the maximum adsorption capacity of 59.64 mg/g. The gel spheres maintained over 80 % efficacy across four adsorption cycles. Kinetic and isotherm analyses revealed that the adsorption of RhB conformed to the secondary kinetic model and the Langmuir isotherm, indicating a spontaneous and exothermic nature of the adsorption process. The adsorption mechanisms of modified LDHs/SA/CMC gel spheres on RhB dyes include electrostatic adsorption, hydrogen bonding and hydrophobic interactions. In conclusion, modified LDHs/SA/CMC gel sphere is a green, simple, recyclable and efficient adsorbent, which is expected to be widely used for the treatment of cationic dye wastewater.