SEPARATION OF COBALT(II) AND NICKEL(II) IONS FROM ACID AQUEOUS SOLUTIONS BY Co IT ION-EXCHANGE INTO γ-TITANIUM PHOSPHATE

Crystalline α-titanium(IV) hydrogenphosphate and its sodium- and n-butylammonium-intercalated forms: ion exchange and thermochemistry

“…1 The selectivity of these compounds towards cations has led to many applications in chromatographic separations. [2][3][4][5][6][7][8][9][10] The initial studies of ion exchangers were focused on hydrated oxides such as ZrO 2 ؒxH 2 O and SiO 2 ؒxH 2 O. These compounds are normally prepared in amorphous or poorly crystalline forms and show amphoteric properties in sorbing or coprecipitating many ions from aqueous solutions.…”

%Calorimetric Determinations of Ba2+ and La3+ in the Ion-Exchange Process Involving Pure and Modified α-Titanium Phosphates

“…This behavior clearly demonstrated that a previous increase in the interlamellar distance favored the exchange. In this process the cations can naturally diffuse inside the lamella and, consequently, cause an increase in the number of cation exchanged, ,− as is expected for the general ion-exchange mechanism. For comparison, the maximum value of barium exchanged for the TPH matrix is 0.66 mmol g -1 , which was increased to 2.78 and 2.77 mmol g -1 for the TPNa and TPBA exchangers, respectively.…”

“…A significant amount of investigations are devoted to ion-exchange reactions, with the great majority focused on structural features of these exchangers, probable in exploring the excellent chemical and thermal stabilities and also the facility in developing favorable ion-exchange properties. , Thus, the ion-exchange behavior of those materials has been applied with the complete series of alkaline metals and calcium, barium, and strontium with the matrixes of titanium and zirconium hydrogen phosphate in α or γ crystalline structures. − However, some thermodynamic data for the ion-exhange reactions are reported for α- or γ-titanium and α- or γ-zirconium phosphates in investigations involving alkaline metals 6-8,11,12 and transition metals Co(II) and Ni(II) with γ-titanium hydrogen phosphate, for which the corresponding ionic isotherms at distinct temperatures were obtained. The same exchange process was followed through calorimetric determinations with crystalline α-titanium phosphate and crystalline or amorphous zirconium phosphate. ,− While the exchange behavior of α-titanium hydrogen phosphate has been investigated, only few studies are found with other kinds of this modified matrix.…”

Hydrothermal Synthesis of Potassium Titanate Powders in Sub/Supercritical Water and Its Cobalt Ion Sorption Properties

“…However, few studies have been reported under hydrothermal conditions. [1][2][3][4][5] Potassium hexatitanate, K2Ti6O13 , possesses a fibrous structure in which the octahedral TiO6 share an edge at one level in a linear groups of three, giving rise to a rectangular tunnel structure incorporated with exchangeable K+ ions. We have demonstrated hydrothermal synthesis of potassium titanates powders and fibrous potassium hexatitanate with relatively large surface area were achieved under subcritical and supercritical conditions.…”