<報文>25℃における Ni(II)-As(III, V)-H_2O 系および Co(II)-As(III, V)-H_2O 系の平衡

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The Ni(II)-As(III)-H_2O, Co(II)-As(III)-H_2O, Ni(II)-As(V)-H_2O and Co(II)-As(V)-H_2O systems have been studied by equilibrating mixtures of nickel (II) or cobalt (II) hydroxide with arsenic (III) or arsenic (V) solution at 25℃. In the first two systems, no arsenite was formed but an adsorption of arsenic (III) by nickel hydroxide or cobalt hydroxide resulted. In the last two systems, the stability and solubility of two nickel arsenates and two cobalt arsenates have been determined as a function of pH. The standard free energies of formation (kcal/mol) have been calculated from the solubility data to be -301.8 for NiHAsO_4・2H_2O, -832.7 for (Ni)_3(AsO_4)_2・8H_2O, -248.8 for CoHAsO_4・H_2O and -841.8 for (Co)_3(AsO_4)_2・8H_2O. The equilibrium log [As(V)]-pH diagrams have been constructed for the Ni(II)-As(V)-H_2O and Co(II)-As(V)-H_2O systems by using the thermodynamic data obtained in this study, and show the relative solubility of arsenic (V) from nickel and cobalt arsenates.nickelcobaltarsenatestabilitysolubilitysolubility constantstandard formation free energy
東北大学の論文
1994-03-30