Synthesis of Crystalline Nanosized α-Hafnium α-Hafnium-Titanium Phosphates from Crystallization of Their Parent Glassy Sodium Forms Via HF Solution and their Polystyrene Nanocomposite Membranes

Glassy hafnium-, hafnium-titanium phosphates, Hf(HPO4)2.3H2O , HfxTi(1-x) (HPO4)2. 3H2O, respectively, (where x= 0.9, 0.67, 0.50) were prepared and characterized. Found to be amorphous with vitreous visual look. Crystalline layered nanosized Hf(HPO4)2.H2O(nHfP) , HfxTi(1-x) (HPO4)2.H2O(nHfTiP),where (x= 0.9, 0.67, 0.50) were prepared from crystallization of their parent glassy sodium forms with HF solution in Pyrex round bottom flask. Size particles of (nHfP) and (nHfTiP) were calculated from XRD broadening method using the Scherer's equation, found to be 10.15,18.69, 18.69,16.92 nm, respectively. They were characterized by chemical, thermal, XRD analysis and Fourier transform spectroscopy (FT-IR). Their exchange capacities were determined. We think these materials crystallized during the conversion process in two steps: 1st their parent glassy sodium forms dissolved in HF solution forming a mixing complex, 2nd the crystalline products were gradually precipitated due to HF solution action on the Pyrex flask and to a certain extent evaporation of excess HF. Preparations of polystyrene/(nHfP)-, (nHfTiP) nanocomposite membranes were carried out by mixing slurry tetrahydrofuran(THF) solution of (nHfP)- , (nHfTiP) of different weight percentages (10, and 20 wt %), with THF solution of 5% polystyrene(PS) in concentration at 45oC with stirring for 48 hours . The resultant mixtures were poured into flat surface containers of desired thickness, respectively , and allowed to dry in air. The resultant fully dried composites were pealed from the glass containers. The composite membranes were transparent flexible thin films and were characterized by XRD, TGA and FT-IR.