Cr (VI) electromechimal reduction using RVG 4OOO graphite felt as the electrode

Abstract

Even in at very low concentrations, heavy metals in industrial waste constitute environmental and health risks. The U.S. Department of Health and Human Services has recognized as chromium compounds and defined carcinogens the level acceptable in drinking water as being only 0.05 ppm. The objective of this work was the electrochemical reduction of hexavalent chromium Cr (VI) to Cr (III) ions in a dilute synthetic solution of K2Cr2O7 and Na2SO4 (0.05N). A plug-flow reactor with an RVG 4000 graphite felt (Le Carbone Lorraine, France) electrode was used for this work. Its morphological characteristics such as specific variables surface, porosity, average fibre diameter and permeability were determined. The influencing process selectivity such as initial concentration of Cr (VI), solution pH, current intensity and conversion yield are considered. The fractional conversion achieved in the plug-flow reactor in the present work, was about 90%

Electrochemical reduction of dilute chromate solutions on carbon felt electrodes

“…Therefore, the treatment of these streams is still ineffective. Chromate reduction on carbon felt was investigated by several groups [14][15][16][17][18]. Carbon felt provides a high specific surface area (app.…”

Insights into Alkali-Acid Leaching of Sericite: Dissolution Behavior and Mechanism

“…Microcrystalline graphite is a natural graphite with a high degree of graphitization and consists of many isotropous microcrystals [1][2][3]. Ore deposits of microcrystalline graphite are generally found in metamorphic rocks or quartzites.…”

“…The theoretical chemical formula of sericite is KSi 3 Al 3 O 10 (OH) 2 and its charge density is close to 1.0 equivalent per O 10 (OH) 2 [8]. Sericite belongs to the clay minerals, and the unit cell is composed of a T-O-T layer, where T represents tetrahedral (SiO 4 ) 4− and O represents octahedral (AlO 3 (OH) 3 ) [9]. Although the dissolution behavior of sericite has been rarely reported, the dissolution of muscovite under acidic or alkaline conditions has been widely studied, thereby also benefitting the understanding of the dissolution mechanism of sericite [10].…”

“…Knauss [11] evaluated the effect of pH (1.4-11.8) on muscovite dissolution rate. Kalinowski [12] studied the kinetics of muscovite dissolution in acidic solutions (pH [1][2][3][4] and found that the dissolution rate depends on pH value. Muscovite dissolution in a high-temperature environment has also been reported [13].…”

Recovery and reuse of hexavalent chromium from aqueous solutions by a hybrid technique of electrodialysis and ion exchange

“…A typical electrochemical process consists of the reduction of chromate at the cathode of a cell to chromium (III) ions, which are precipitated and removed as highly insoluble species, normally Cr(OH) 3 , at a later stage. Since this precipitate is capable of blocking the cathode surface, different approaches have been devised for its removal, either by chemical dissolution or by electrochemical means through potential inversion so as to re-oxidize it to soluble chromate and produce more concentrated Cr(VI) solution for reuse (Abda et al, 1991;Golub and Oren, 1989;Vilar et al, 2003).…”