Hybrid porous magnetic bentonite-chitosan beads for selective removal of radioactive cesium in water

• Published in: Journal of hazardous materials Vol. 362; pp. 160 - 169
• Main Authors: Wang, Kexin, Ma, Hui, Pu, Shengyan, Yan, Chun, Wang, Miaoting, Yu, Jing, Wang, Xiaoke, Chu, Wei, Zinchenko, Anatoly
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.01.2019
• Subjects: adsorbents; adsorption; Bentonite; binding sites; cations; Cesium; chitosan; equations; Hydrogel beads; lithium; magnesium; magnesium chloride; Magnetic adsorbent; magnetism; potassium; radioactive waste; Radioactive wastewater; recycling; sodium; sorption isotherms; waste disposal; Magnetic adsorbent; Bentonite; Cesium; Hydrogel beads; Radioactive wastewater
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2018.08.067

[Display omitted] •The magnetic bentonite-chitosan beads were synthesized as adsorbent for Cs+ removal.•The porous adsorbent functioned by the synergistic effect of bentonite and chitosan.•Bentonite-chitosan beads capture Cs+ selectively in presence of the co-existing cations.•Adsorbent was recycled by 0.1 mol L−1 of Mg2+ for quantitative desorption of Cs+ from beads. Easy-to-obtain magnetic bentonite-chitosan hybrid beads (Bn-CTS) were prepared by immobilizing bentonite within a porous structure of chitosan beads to achieve a hybrid adsorption effect for the removal of cesium ion (Cs+) from water. The hybrid adsorbent, which had a porous structure and abundant binding sites contributed by both chitosan and bentonite, ensured superb adsorption characteristics. The paramagnetic character of the beads enabled their facile separation for recycling. The chitosan/bentonite ratio, pH and contact time were optimized to achieve the optimal Cs+ efficiency, and the adsorption kinetics and isotherms were thoroughly discussed. The adsorption kinetics obeyed the pseudo-second-order model, and the best fitted equation for equilibrium data was the Langmuir isotherm model. The maximum adsorption capacity of the bentonite-chitosan beads was 57.1 mg g−1. The adsorbent had excellent selectivity towards Cs+ adsorption in the presence of abundant cations (Li+, Na+, K+ and Mg2+). The adsorbent was able to be recycled by treating the beads with 0.1 mol L−1 of MgCl2 to quantitatively desorb Cs+ from the beads. Overall, the magnetic bentonite-chitosan beads can be used as a highly efficient adsorbent for radioactive waste disposal and management.