A new water sorbent mesostructured metal silicate has been developed by a cost-effective and environmental friendly two-step preparation method. The material possesses interparticle mesopores with pore dimensions between 4 and 29 nm and a surface area of 712 m2. The water sorption capacity of this material is 0.21 g/g. The water capacity has been improved by the preparation of the composite using mesostructured metal silicate as matrix and salt hydrate CaCl2. This composite possesses 3 times higher water sorption capacitythan pure matrix.
COBISS.SI-ID: 4649754
Zeolite NaP and MgNaP show type VI water isotherm, which indicates on hydrophilic material with multiple sorbent-water interactions and stepwise sorption. The sorption characteristics of Ca-exchanged samples were changed (water isotherm type III), evidencing the preparation of low hydrophilic materials with weak sorbent-water interactions, while Li-exchanged products indicate on hydrophobic character of these materials.
COBISS.SI-ID: 4774682
The thermal stability of the material was studied by thermogravimetric analysis (TG) and high temperature X-ray diffraction (HT XRD). The measurements show four major weight losses from room temperature to 973 K. The departure of water molecules from the pores was completed at 150 °C. The material starts to decompose at 300 °C. The in situ XAS study was applied to follow the changes in oxidation state and coordination of iron during the heating process. XANES and EXAFS spectra indicate that at room temperature the iron is 6-coordinated in trivalent oxidation state. When heating the sample, the changes in iron local structure appear and at 420 °C structure degradation was determined. Material shows high durability and structural resistance in boiling water for different periods of time. The study proved that the material is an excellent candidate for heat storage applications.
COBISS.SI-ID: 4703770