Kinetics of water freezing in mesopores of silica gel.

The research presented in the manuscript aims at the determination of the kinetic model of water freezing in mesopores using differential scanning calorimetry. The microstructure of the silica gels under investigation have one dominant pore diameter, which equals 15 nm. Additionally, their microstructure is investigated using the nitrogen adsorption/desorption techniques before and after freezing cycles. We test four cooling rates: 2.5 °C/min; 5.0 °C/min; 7.5 °C/min and 10.0 °C/min. The relation between ice content and temperature is determined for each cooling rate. We find that the process rate depends only on the temperature and the extent of conversion. The activation energy is determined by differential Friedman’s method. Three algorithms for the determination of model parameters are compared: Málek method, the method proposed by Perez-Maqueda et al., and the one introduced by Arshad and Maaroufi. The Šesták-Berggren model gives the best approximation of the conversion function.