Loebenstein William V
Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234.
J Res Natl Bur Stand A Phys Chem. 1975 Jul-Aug;79A(4):565-576. doi: 10.6028/jres.079A.019.
It is standard procedure to fit an applicable isotherm equation to water vapor adsorption data using the method of least squares in arriving at a value for the surface area accessible to the water molecule. The least squares technique has been extended in the present investigation to determine, in addition and simultaneously, a "best value" for the zero-humidity sample weight of the material. The application is equally valid for desorption insofar as the zero-humidity weight is concerned, although the derived value for "surface area" from desorption data will be over-estimated in the general case because of hysteresis. There is no limitation on the range of humidities since the method is not restricted to the BET equation (i.e., between 0.1 and 0.3 r.h.). In fact, good agreement with the zero-humidity points measured experimentally has been obtained even from drying curves in which the relative humidity has been confined to the region above 50 percent. An iterative method is employed in the calculations for which computer assistance is especially adaptable. Fortran IV programs are included in the appendix whose use requires no extensive computer experience. A fraction of a second in computer processing time is all that is required for each determination.
使用最小二乘法将适用的等温线方程拟合到水蒸气吸附数据上，以得出水分子可及表面积的值，这是标准程序。在本研究中，最小二乘法得到了扩展，以便同时确定该材料零湿度样品重量的“最佳值”。就零湿度重量而言，该应用对于解吸同样有效，尽管在一般情况下，由于滞后现象，从解吸数据得出的“表面积”值会被高估。湿度范围没有限制，因为该方法不限于BET方程（即相对湿度在0.1至0.3之间）。实际上，即使在相对湿度限制在50%以上区域的干燥曲线中，也能与实验测量的零湿度点取得良好的一致性。计算中采用了迭代方法，计算机辅助对此特别适用。附录中包含Fortran IV程序，其使用不需要广泛的计算机经验。每次测定只需要计算机处理时间的一小部分。
