Layered double hydroxide stability. 2. Formation of Cr(III)-containing layered double hydroxides directly from solution.
Solutions containing divalent metal [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+] chlorides and CrCl3 6H2O were titrated with NaOH to yield, for M(II) = Zn, Co, and Ni, hydrotalcite-like layered double hydroxides (LDHs), [[M(II)]1-z[Cr(III)]z(OH)2][Cl]z yH2O, in a single step, without intermediate formation of chromium hydroxide. Analysis of the resultant titration curves yields solubility constants for these compounds. These are in the order Zn < Ni approximately Co, with a clear preference for formation of the phase with z = 1/3. With Mg2+ as chloride, titration gives a mixture of Cr(OH)3 and Mg(OH)2, but the metal sulfates give Mg2Cr(OH)6 1/2(SO4) by a two-step process. Titrimetric and spectroscopic evidence suggests short-range cation order in the one-step LDH systems.
Boclair
J W
JW
Department of Chemistry, University of North Texas, Denton 76203-5070, USA.
Braterman
P S
PS
Jiang
J
J
Lou
S
S
Yarberry
F
F
D000838:Anions / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D017608:Chromium Compounds / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry; D008345:Manganese / Q000737:chemistry; D008670:Metals / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry; D012995:Solubility; D012996:Solutions; D013431:Sulfates / Q000737:chemistry; D017186:Titrimetry; D015032:Zinc / Q000737:chemistry
D000838:Anions; D002412:Cations; D002712:Chlorides; D017608:Chromium Compounds; D006878:Hydroxides; D008670:Metals; D012996:Solutions; D013431:Sulfates; D002857:Chromium; C040874:chromium sulfate; D003035:Cobalt; D008345:Manganese; D009532:Nickel; D008274:Magnesium; D015032:Zinc; C022990:chromic chloride