Thermodynamic properties of microporous materials for two borophosphates, K[ZnBP2O8] and NH4[ZnBP2O8]

Two pure borophosphates microporous materials, K[ZnBP 2 O 8 ] and NH 4 [ZnBP 2 O 8 ], have been synthesized and characterized by XRD, FT-IR, DTA-TG techniques and chemical analysis. The molar enthalpies of solution of K[ZnBP 2 O 8 ](s) and NH 4 [ZnBP 2 O 8 ](s) in 3   mol   ·   dm −3 HCl(aq), of KCl/NH 4 Cl(s) in (HCl   +   H 3 BO 3 )(aq), and of Zn(PO 3 ) 2 (s) in (HCl   +   H 3 BO 3   +   KCl/NH 4 Cl)(aq) were measured by microcalorimeter at T   =   298.15   K, respectively. With the incorporation of the previously determined enthalpy of solution of H 3 BO 3 (s) in 3   mol   ·   dm −3 HCl(aq), together with the use of the standard molar enthalpies of formation for Zn(PO 3 ) 2 (s), KCl(s), NH 4 Cl(s), H 3 BO 3 (s) and H 2 O(l), the standard molar enthalpies of formation of −(3184.0   ±   1.2)   kJ   ·   mol −1 for K[ZnBP 2 O 8 ] and −(3067.6   ±   1.2)   kJ   ·   mol −1 for NH 4 [ZnBP 2 O 8 ] at T   =   298.15   K was obtained on the basis of the appropriate thermochemical cycles.