Rootare H M, Craig R G
J Dent Res. 1977 Dec;56(12):1437-48. doi: 10.1177/00220345770560120101.
Water vapor adsorption isotherms were determined gravimetrically on three hydroxyapatite sampel differing in preparation and with surface areas of 70.4, 22.5, and 3.0 M2/gm, respectively. Heats of adsorption for the first layer of water were found to be 13.3, 13.2, and 13.9 kcal/mole on these hydroxypatites. From repeated thermal desorption and adsorption cycles of water, stepwise adsorption was observed which diminished with each outgassing cycle until it disappeared after the fourth cycle. Cross-sectional area of adsorbed water molecule on hydroxyapatite surface was estimated at 11.5 A2. Standard free energies, isosteric heats, changes in enthalpy, and entropy of adsorption of water on HAP samples outgassed at 300 C were determined.
通过重量法测定了三种制备方法不同、表面积分别为70.4、22.5和3.0平方米/克的羟基磷灰石样品的水蒸气吸附等温线。在这些羟基磷灰石上，第一层水的吸附热分别为13.3、13.2和13.9千卡/摩尔。通过水的反复热脱附和吸附循环，观察到逐步吸附现象，这种现象随着每次除气循环而减弱，直到在第四个循环后消失。估计羟基磷灰石表面吸附水分子的截面积为11.5埃²。测定了在300℃除气的羟基磷灰石样品上水吸附的标准自由能、等量吸附热、焓变和熵变。
