Cesium adsorption and distribution onto crushed granite under different physicochemical conditions

NCUIR > College of Earth Sciences > Graduate Institute of Hydrological and Oceanic Sciences > journal & Dissertation > Item 987654321/36009

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Title:	Cesium adsorption and distribution onto crushed granite under different physicochemical conditions
Authors:	Tsai,SC;Wang,TH;Li,MH;Wei,YY;Teng,SP
Contributors:	水文科學研究所
Keywords:	AQUEOUS CS+ IONS;SUBSURFACE SEDIMENTS;HANFORD SITE;SORPTION;CLAY;MINERALS;IRON;RADIOCESIUM;BENTONITE;REMOVAL
Date:	2009
Issue Date:	2010-07-08 09:29:38 (UTC+8)
Publisher:	中央大學
Abstract:	The adsorption of cesium onto crushed granite was investigated under different physicochemical conditions including contact time, Cs loading, ionic strength and temperature. In addition. the distribution of adsorbed Cs was examined by X-ray diffraction (XRD) and EDS mapping techniques. The results showed that Cs adsorption to crushed granite behaved as a first-order reaction with nice regression coefficients (R-2 >= 0.971). Both Freundlich and Langmuir models were applicable to describe the adsorption. The maximum sorption capacity determined by Langmuir model was 80 mu mol g(-1) at 25 degrees C and 10 mu mol g(-1) at 55 degrees C. The reduced sorption capacity at high temperature was related to the partial enhancement of desorption from granite surface. In general, Cs adsorption was exothermic (Delta H < 0, with median of -12 kJ mol(-1)) and spontaneous (Delta G < 0, with median of -6.1 at 25 degrees C and -5.0 kJ mol(-1) at 55 degrees C). The presence of competing cations such as sodium and potassium ions in synthetic groundwater significantly reduces the Cs adsorption onto granite. The scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM/EDS) mapping method provided substantial evidences that micaceous minerals (biotite in this case) dominate Cs adsorption. These adsorbed Cs ions were notably distributed onto the frayed edges of biotite minerals. More importantly, the locations of these adsorbed Cs were coincided with the potassium depletion area, implying the displacement of K by Cs adsorption. Further XRD patterns displayed a decreased intensity of signal of biotite as the Cs loading increased, revealing that the interlayer space of biotite was affected by Cs adsorption. (C) 2008 Elsevier B.V. All rights reserved.
Relation:	JOURNAL OF HAZARDOUS MATERIALS
Appears in Collections:	[Graduate Institute of Hydrological and Oceanic Sciences] journal & Dissertation

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