Interaction between aqueous chromium solutions and layer silicates

Brigatti, Maria Franca; Franchini, Giancarlo; Lugli, Cristina; Medici, Luca; Poppi, Luciano; Turci, Elisa

doi:10.1016/s0883-2927(99)00120-1

Cited by 54 publications

(38 citation statements)

References 24 publications

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“…Further, while the enhanced formation of Cr(VI) by calcium oxides was discussed on the basis of leaching tests, the dissolution of Cr(VI) was also investigated in practical ferrochromium slag. 4,5) In order to change the chemical state of Cr(VI), the reduction of Cr(VI) contained in slag and that dissolved in water was studied by using additives such as copper smelter slag, 6) silicates 7) bacteria 8) and also by using heat treatments. 9,10) In most of these studies, the concentration of Cr(VI) dissolved in water has been analyzed.…”

Section: Introductionmentioning

confidence: 99%

Chemical State of Chromium in CaO–SiO2 Base Oxides Annealed under Different Conditions

et al. 2008

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In order to understand the formation mechanism of Cr(VI) in chromium-containing steel slag, X-ray diffractiometry (XRD), X-ray absorption spectroscopy (XAS) in the region of X-ray absorption near edge structure (XANES), and X-ray photoelectron spectroscopy (XPS) measurements were performed for analyzing the chromium contained in the model slag of CaO-SiO 2 base. The model slag was annealed under different temperatures and atmospheres to change the chemical state of chromium. XRD results showed that a diffraction peak that can be assigned to CaCrO 4 comprising of Cr(VI) was detected in the model-slag sample annealed under a high partial pressure of oxygen (air). XANES results showed that the Cr(VI) concentration in the slag increased by annealing under a high partial pressure of oxygen, while it was very low in the slag sample annealed under a low partial pressure of oxygen. The XANES results were consistent with the XRD results. The formation conditions of Cr(VI) were discussed on the basis of the thermodynamic characteristics of a Ca-Cr-O system. The XPS results for the slag surface were dependent on the leaching tests performed on the slag, while the XANES results were insensitive to the leaching tests. This indicates that Cr(VI) dissolved from only a surface layer of the model slag. The chromium that dissolved from the slag in an aqueous solution by the leaching test was also analyzed and was found to be in the form of Cr(VI); further, its concentration depended on the annealing conditions of the slag.

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Section: Introductionmentioning

confidence: 99%

Chemical State of Chromium in CaO–SiO2 Base Oxides Annealed under Different Conditions

et al. 2008

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“…However, metals also play a critical role on the environment, since they are frequently used in such a way that their availability for plants is toxic [1]. Translocation of heavy metals, like Cu, Zn, Cd and Pb, in plants is difficult and this may be related to the facile complexation involving these metals and the aminoacids in plants, which produces stable structures with high steric hindrance [2]. Diethylenetriaminepentaacetic acid, DTPA (Fig.…”

Section: Introductionmentioning

confidence: 99%

Spectrometric and theoretical investigation of the structures of Cu and Pb/DTPA complexes

et al. 2007

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Spectrometric and theoretical tools have been employed in this study in order to elucidate the structures of DTPA (diethylenetriaminepentaacetic acid) complexed to copper and lead. Mass spectrometry allowed determining the 1:1 stoichiometry of metal:ligand, while infrared spectroscopy demonstrated that both N and O are sites for complexation. 13 C NMR analysis showed the existence of free and complexed carboxyl groups, due to a straight singlet at 180.7 ppm (free carboxylic 13 C) and to a broad signal at 179.3 ppm (complexed carboxylic 13 C, 2 J Pb…O=C ). A distorted NMR signal were observed for the Cu-DTPA carboxyl group, due to the Cu 2+ paramagnetism. Based on the spectrometric evidences for the metal-DTPA structures, DFT optimizations were carried out and an octahedral-like arrangement for the Cu complex and a ''shell-like'' arrangement for the Pb complex, both hexacoordinated, were then proposed for the structures of the titled compounds.

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“…Furthermore, these processes are strongly affected by the pH of the aqueous solution (Liu et. al., 2004;Chen and Lin, 2001;Brigatti et al, 2000). The influence of pH is generally attributed to the variation, with pH, in the relative distribution of the metal and carbon surface species, in their charge and proton balance (Csobán et al, 1998;Kratochvil and Volesky, 1998).…”

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confidence: 99%

“…The majority of studies on the sorption kinetics have revealed a two-step behaviour of the adsorption systems (Brigatti et al, 2000;Csobán et al, 1998;Raji et al, 1998) with fast initial uptake and much slower gradual uptake afterwards, which might take days even months Csobán et al, 1998;Raji et al, 1998;Kumar et al, 2000;Ajmal et al, 2001;Lakatos et al, 2002;Chakir et al, 2002;Leist et al, 2000;Csobán & Joó, 1999). Some of the authors reported the optimum contact time of minutes (Kumar et al, 2000;Ajmal et al, 2001), whereas, at the other extreme, that of hundred hours (Brigatti et al, 2000;Lakatos et al, 2002) for equilibrium to be attained; and the average values reported for the heavy metal binding were of 1-5 hours (Csobán et al, 1998;Raji et al, 1998;Chakir et al, 2002;Leist et al, 2000;Csobán and Joó, 1999). It has been also stressed that adsorption thermodynamics is drastically affected by the equilibrium pH of the solutions.…”

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confidence: 99%

Comparison of the Thermodynamic Parameters Estimation for the Adsorption Process of the Metals from Liquid Phase on Activated Carbons

Lyubchik¹,

Lyubchik²,

Lygina³

et al. 2011

Thermodynamics - Interaction Studies - Solids, Liquids and Gases

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Interaction between aqueous chromium solutions and layer silicates

Cited by 54 publications

References 24 publications

Chemical State of Chromium in CaO–SiO2 Base Oxides Annealed under Different Conditions

Chemical State of Chromium in CaO–SiO2 Base Oxides Annealed under Different Conditions

Spectrometric and theoretical investigation of the structures of Cu and Pb/DTPA complexes

Comparison of the Thermodynamic Parameters Estimation for the Adsorption Process of the Metals from Liquid Phase on Activated Carbons

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