Evaluation of Cs+ removal from aqueous solution by adsorption on ethylamine-modified montmorillonite

• A novel material was found to remove radiocesium effectively.
• Different adsorption behaviors between modified and raw clay were compared.
• The adsorption mechanism was discussed through the chemical process.

In this study, the adsorption performance of ethylamine-modified montmorillonite (Ethyl-Mt) and calcium-saturated montmorillonite (Ca-Mt) were evaluated by Cs+ adsorption experiments considering the influencing factors (initial solution pH, contact time, initial Cs+ concentration, temperature and ionic strength). FTIR, BET, SEM, EDS and Zeta potential analysis were used to characterize the surface properties of Ethyl-Mt and Ca-Mt. Experimental results demonstrated that the equilibrium uptake of Cs+ was highly pH-dependent. Pseudo-second-order model fitted well with the adsorption kinetic studies. The adsorption processes were described by Langmuir model with maximum adsorption capacity of 60.03 mg g−1 and 80.27 mg g−1 for Ca-Mt and Ethyl-Mt, respectively. Also, the thermodynamic studies showed that the adsorption of Cs+ was spontaneous and exothermic in nature. The presence of cations such as Na+, K+, Ca2+ astricted the adsorption of Cs+. The Cs+ removal on Ca-Mt was mainly ion exchange, while that on Ethyl-Mt would also involve coordination and surface complexation. On the basis of our results, Ethyl-Mt with high adsorption capacity and good surface characteristics is beneficial to be used for removal of Cs+.

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