Characterization and Preliminary Assessment of a Sorbent Produced by Accelerated Mineral Carbonation

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• 作者：Olga L. Shtepenko ; Colin D. Hills ; Nichola J. Coleman ; and Adrian Brough
• 刊名：Environmental Science & Technology
• 出版年：2005
• 出版时间：January 1, 2005
• 年：2005
• 卷：39
• 期：1
• 页码：345 - 354
• 全文大小：536K
• 年卷期：v.39,no.1(January 1, 2005)
• ISSN：1520-5851

文摘

This study shows that calcium silicate/aluminate-basedmaterials can be carbonated to produce sorbents for metalremoval. The material chosen for investigation, cementclinker, was accelerated carbonated, and its structuralproperties were investigated using X-ray diffraction (XRD),scanning electron microscopy, thermal gravimetric anddifferential thermal analysis, nuclear magnetic resonancespectroscopy, and nitrogen gas adsorption techniques.The principal carbonation reactions involved the transformation of dicalcium silicate, tricalcium silicate, and tricalciumaluminate into a Ca/Al-modified amorphous silica andcalcium carbonate. It was found that carbonated cementhad high acid buffering capacity, and maintained its structuralintegrity within a wide pH range. The uptake of Pb(II), Cd(II), Zn(II), Ni(II), Cr(III), Sr(II), Mo(VI), Cs(I), Co(II), and Cu(II) from concentrated (1000 mg L^-1) single-metal solutionsvaried from 35 to 170 mg g^-1 of the carbonate cement.The removal of metals was hardly effected by the initialsolution pH due to the buffering capability of the carbonatedmaterial. The kinetics of Pb, Cd, Cr, Sr, Cs, and Coremoval followed a pseudo-second-order kinetic model,whereas the equilibrium batch data for Cu fitted the pseudo-first-order rate equation. PHREEQC simulation supportedby XRD analysis suggested the formation of metal carbonatesand silicates, calcium molybdate, and chromium (hydro)oxide. Cesium was likely to be adsorbed by Ca/Al-modifiedamorphous silica.