Efficiency of bentonite in removing cesium, strontium, cobalt and uranium ions from aqueous solution: encapsulation with alginate for column application

ABSTRACT

Raw bentonite was characterised and employed for adsorption of Cs(I), Sr(II), Co(II) and U(VI) from aqueous solution. Batch adsorption methodology was applied to study the factors influencing the adsorption capacity of bentonite. Thermodynamic parameters, ΔH°, ΔS°, and ΔG° were calculated and revealed that the sorption process is spontaneous and has endothermic nature. The isotherm studies revealed that Langmuir is more applicable than Freundlich isotherm. The maximum sorption capacity (Q0) for the studied sorbent towards Cs (I), U(VI), Co(II) and Sr (II) was 50, 33.3, 25 and 14.29 mg/g, respectively. To overcome the aggregation for clay flacks of bentonite in column,- an innovative microcapsule of alginate enclosing with bentonite was developed and characterised for removal of these ions from multi-component solution. The results revealed that bentonite and bentonite-alginate demonstrated high adsorption capacity at the same pH 5.5. The breakthrough curve had S-shaped profile. The breakthrough capacity of Cs(I), U(VI), Sr(II) and Co(II) was found to be 11.75, 11.1, 8.73 and 11 mg/g, respectively. The total capacity and the total removal percent, (R_total%), were established to be 42.58 mg/g and 58.4%, respectively. The results showed that there are some great separation done by elution using 4 M NaNO₃ and 4 M HNO₃.

KEYWORDS:

• Bentonite
• alginate
• encapsulation
• equilibrium
• thermodynamics
• column
• separation

Disclosure statement

No potential conflict of interest was reported by the author(s).