Determination of pore size distributions by regularization and finite element collocation

Abstract

The problem of extracting pore size distributions from characterization data is solved here with particular reference to adsorption. The technique developed is based on a finite element collocation discretization of the adsorption integral, with fitting of the isotherm data by least squares using regularization. A rapid and simple technique for ensuring non-negativity of the solutions is also developed which modifiesthe original solution having some negativity. The techniqueyields stable and converged solutions, and is implementedin a package RIDFEC. The package is demonstrated to berobust, yielding results which are less sensitive to experimental error than conventional methods, withfitting errors matching the known data error. It is shownthat the choice of relative or absolute error norm in the least-squares analysisis best based on the kind of error in the data.