Structure and adsorption properties of the composites ‘silica gel–sodium sulphate’, obtained by sol–gel method

• The composites ‘silica gel–sodium sulphate’ are synthesized by sol–gel method.
• Their sorption properties exceed Na2SO4 and silica gel mechanical mixture.
• The composites hydratation is controlled with water transport on matrix pore system.
• The composite heat energy storage capacity is 0.36 kWh/kg or 258 kWh/m3.

The composite sorbents ‘silica gel–sodium sulphate’ synthesized by sol–gel method are studied. The sorption capacity of the composite ‘silica gel–sodium sulphate’ is stated to be 0.85 g/g that exceeds noticeably the linear superposition of the sorption capacity of the silica gel and sodium sulphate mechanical mixture which is 0.66 g/g. The composite ‘silica gel–sodium sulphate’ composition and structure are studied by IR-spectroscopy and wide-angle X-ray scattering. The changing of adsorption properties of crystalline Na2SO4 at their allocation in silicon–oxygen matrix is shown to be result from dispersion up to nanoscale. The experimental setup for effectiveness tests of synthesized composite sorbents is developed. The correlation of their composition, structure, water adsorption kinetic and operating characteristic as heat storage material is shown. The heat storage capacity is stated to be 0.36 kWh/kg (258 kWh/m3).