Sorption of cesium on bentonite

Journal Article · Fri Dec 31 23:00:00 EST 1993 · Waste Management; (United States)

DOI:https://doi.org/10.1016/0956-053X(94)90035-3· OSTI ID:6698074

Khan, S A; Khan, M A ^[1]

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1. Univ. of the Punjab, Lahore (Pakistan). Inst. of Chemistry

Sorption of Cs on bentonite has been studied by using batch technique. Distribution coefficients (K[sub d]) were determined for bentonite-cesium solution system as a function of contact time, pH, sorbent and sorbate concentration and temperature. Sorption data have been interpreted in terms of Freundlich, Langmuir and Dubnin-Radushkevich equations. Thermodynamic parameters for the sorption system have been determined at three different temperatures. The value of [Delta]H[degree] = [minus]32.29 KJ/mol and [Delta]G[degree] = [minus]13.16 KJ/mol at 298 K suggests that the sorption of cesium on bentonite is an exothermic and a spontaneous process. [Delta]G[degree] becomes less negative at higher temperatures and therefore less cesium is sorbed at higher temperatures. The mean free energy E [approximately] 14.5 KJ/mol for cesium sorption shows that ion-exchange is the predominant mode of sorption at 0.01--0.5 molar cesium concentration. The presence of complementary cations depress the sorption of cesium on bentonite in the order of K[sup +] > Ca[sup 2+] > Mg[sup 2+] > Na[sup +]. Some organic complexing agents and natural ligands also affect the sorption of cesium. The desorption studies with 0.01 M CaCl[sub 2] and ground water at low cesium loading on bentonite show that about 95% of the element is irreversibly sorbed probably due to the fixation of the cesium by isomorphous replacement in the crystal lattice of the sorbent.

• OSTI ID: 6698074
• Journal Information: Waste Management; (United States), Journal Name: Waste Management; (United States) Vol. 14:7; ISSN WAMAE2; ISSN 0956-053X
• Country of Publication: United States
• Language: English

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