TY - JOUR TI - Comparing the solubility products of layered Me(II)-Al(III)-hydroxides based on sorption studies with Ni(II), Zn(II), Co(II), Fe(II), and Mn(II) DO - https://doi.org/doi:10.7282/T34X5BVW PY - 2017 AB - The sorption of divalent metals onto Al-oxide sorbents may lead to the formation of mixed metal-aluminum layered double hydroxide (Me(II)-Al(III)-LDH) phases. The formation of these secondary phases may represents a significant pathway of sequestration of various divalent metals, including Ni(II), Zn(II), Co(II), Fe(II) and Mn(II), in aqueous geochemical environments such as soils and sediments. Despite of their importance in metal sequestration there is not enough thermodynamic data available to model their behavior in geochemical environment. Thus this study was designed to estimate the solubility product values of Me(II)-Al(III)-LDH precipitates formed by Ni(II), Zn(II), Co(II), Fe(II) and Mn(II) during sorption onto Al-oxide at near neutral and alkaline pH value in NaCl electrolyte. Detailed kinetic studies were conducted to monitor the sorption of these divalent metals ¬¬onto γ-Al2O3. Equilibrium aqueous metal concentrations were used to calculate the solubility products (Ksp) of the Me(II)-Al(III)-LDH phases for the aqueous chemical equilibrium described by: Me(II)2/3Al(III)1/3(OH)2Cl1/3(s) ↔ 2/3 Me(II)(aq) + 1/3 Al(III) (aq) + 2OH- (aq) +1/3 Cl- (aq) The Ksp values of the five metals span three orders of magnitude, indicating substantial differences in the favorability of Me(II)-Al(III)-LDH precipitation, which increases in the order Mn(II)