Critical Evaluation and Selection of Standard State Thermodynamic Properties for Chromium Metal and Its Aqueous Ions, Hydrolysis Species, Oxides, and Hydroxides

Abstract

This review critically evaluates the reported thermodynamic data on chromium metal, oxides, hydroxides, free aqueous ions, and hydrolysis species. Several discrepancies and inconsistencies have been uncovered and resolved to improve equilibrium calculations for chemical modeling and related engineering purposes. A revised set of data is derived from evaluation of electrochemical measurements, silver chromate solubility measurements, and auxiliary post-1980 data, reevaluation of earlier data, and reconsideration of the path for the thermodynamic network. The recommended thermodynamic values for Cr(cr), C , C , Cr , Cr2 , Cr2O3(cr), CrO3(cr), FeCr2O4(cr), CrCl2(cr), CrCl3(cr), and KFe3(CrO4)2(OH)6(cr) at 25 °C, 1 bar, and infinite dilution are given.

Genesis of hexavalent chromium from natural sources in soil and groundwater

“…The larger production rate of aqueous Cr(VI) with decreasing pH (Fig. 2C) is consistent with the solubility of chromite (and birnessite) being inversely related to pH (15). Furthermore, as shown in Fig.…”

“…Although chromite [FeCr(III) 2 O 4 ] is the primary source of Cr in ultramafic and serpentinite rocks (13), it exhibits very low solubility under most geologic and industrial refining conditions (14)(15)(16), and there are few naturally occurring oxidants of Cr(III). The only natural oxidants of aqueous Cr(III) at pH Ͻ 9 are Mn(IV/III)-oxides (17)(18)(19)(20)(21) and hydrogen peroxide (H 2 O 2 ) (22).…”

Questa baseline and pre-mining ground-water quality investigation. 25. Summary of results and baseline and pre-mining ground-water geochemistry, Red River Valley, Taos County, New Mexico, 2001-2005

“…The two geochemical models used for speciation and mineral saturation calculations in this study were the WATEQ4F code (Ball and Nordstrom, 1991, which has been regularly updated since then) and the PHREEQC code (Parkhurst, 1995;Parkhurst and Appelo, 1999, which has also been regularly updated and enhanced). Both codes use the same thermodynamic database that is occasionally updated through critical evaluations (Nordstrom and others, 1990;Nordstrom and May, 1996;Ball and Nordstrom, 1998;Nordstrom and Archer, 2003; notes to recent versions of WATEQ4F, James Ball, written commun., 1995-present). To document the database used for the computations in this report, a compilation of the thermodynamic data has been tabulated in table 1-1 of Appendix 1.…”

Removal of Cr(III) from Synthetic Wastewater by using a Strong Cation Exchange Resin

“…Sorbente metal katyonlarının sorpsiyonu sorbent yüzeyinin doğasına ve metal katyon türlerinin dağılımına bağlıdır (Aşçı and Şefika, 2016 formları baskın olur. Ancak, Cr(OH) 3(s) pH 5.5-12 aralığında çok az çözünür (pH 6.5 ve 11.5 arasında minumum; (Richard and Bourg, 1991;Ball and Nordstrom, 1998;Kotas and Stasicka, 2000) ve bu pH aralığı aynı zamanda önemli doğal suların da pH aralığına karşılık gelir (Şekil 2). ) oluşur (Kotas and Stasicka, 2000;Kumral, 2007).…”