Influence of pore structure on humidity control performance of diatomite

Abstract

The moisture adsorption and desorption performance of five diatomite samples with different pore structures were tested under high and low relative humidity (98% and 11% relative humidity) and constant temperatures of 20°C and 30°C. The mineral compositions and surface morphologies of diatomite samples were characterized by x-ray diffraction and scanning electron microscopy, respectively. The pore structure of diatomite samples were analyzed by nitrogen gas adsorption and mercury intrusion porosimetry. The relationship of pore structure and humidity control performance were analyzed and discussed. It is indicated that the humidity control performance of diatomite in general enhances as the environmental temperature increases. The Shengxian diatomite presents better humidity control performance among these five samples. According to the dynamics study, the moisture adsorption and desorption performance follow the pseudo-second-order model. The mesoporous in diatomite is vitally important for the humidity controlling. The specific surface area and mesoporous volume are the two key factors for the moisture adsorption and desorption ability. Diatomite with high specific surface area and large mesoporous volume has better humidity control performance. Moreover, the impurities could change the pore structure, then further affect the humidity control performance of diatomite.