温湿度对不同吸湿剂吸湿特性及动力学模型影响

Effect of Temperature and Relative Humidity on Absorption Characteristics and Kinetic Models of Different Absorbent

摘要:

采用静态吸附法研究了无水氯化钙、六偏磷酸钠、山梨糖醇、魔芋葡甘聚糖、壳聚糖、活性氧化铝粉和膨润土等7种吸湿剂在不同温度（2、10、18 ℃）和相对湿度RH（76%、86%、96%）下放置15 d时的吸湿特性。结果表明，温度一定时，吸湿量随RH升高而增加；RH一定时，吸湿量随温度变化略有差异。采用Weibull模型拟合吸湿量数据，得到吸湿动力学参数M∞和β，通过线性回归得到M∞和温湿度的关系。除山梨糖醇外，Weibull模型与吸湿量拟合精度较高。M∞较高的吸湿剂为无水氯化钙（1.117~2.137 g H2O/g）、六偏磷酸钠（0.297~0.856 g H2O/g）和山梨糖醇（0.083~38.567 g H2O/g），其β值范围为：无水氯化钙（25.5~119.8 h）、六偏磷酸钠（91.2~290.0 h）和山梨糖醇（1.1~185.6 h）。壳聚糖和膨润土的M∞受温度、RH的共同影响，而六偏磷酸钠和山梨糖醇的M∞仅受RH的影响。研究结果可为双孢蘑菇MA贮藏期间RH控制提供理论依据。

Abstract:

The static adsorption method was employed to investigate the moisture absorption characteristics of seven different moisture absorbents, including calcium chloride (CaCl2), sodium hexametaphosphate, sorbitol, konjac glucomannan (KGM), chitosan, activated aluminum oxide powder, and bentonite, which were exposed to different temperatures (2 ℃, 10 ℃, and 18 ℃) and relative humidities (RHs) (76%, 86%, and 96%) for 15 days. The results showed that moisture absorption for the same absorbent increased with increasing RH at a fixed temperature, while moisture absorption varied for different absorbents with elevated temperature at a fixed RH. The Weibull model was used to fit the experimental moisture content data; the model parameters of M∞ and β were obtained, and the relationship between M∞ and temperature/humidity was established using linear regression analysis. Except for sorbitol, the accuracy of fit of the moisture content data to the Weibull model was high. The moisture absorbents with high holding capacities (M∞) were CaCl2 (1.117~2.137 g H2O/g), sodium hexametaphosphate (0.297~0.856 g H2O/g), and sorbitol (0.083~38.567 g H2O/g), with β ranges of 25.5~119.8 h, 91.2~290.0 h, and 1.1~185.6 h, respectively. The M∞ values of chitosan and bentonite were found to be dependent on temperature and RH, while those of sodium hexametaphosphate and sorbitol were only affected by RH. These results will provide a theoretical basis for RH control during modified atmosphere (MA) storage of Agaricus bisporus.