Evaluation of chemical indexes to predict the dissolution rate of amorphous silicate fibers in a physiological salt solution

Abstract

In order to predict the biosolubihty of amorphous inorganic fibers through a chemical index, dissolution experiments were carried out of the amorphous silicate fibers in the RO-SiO2 system (RO: alkaline earth oxide such as MgO, CaO and SrO) in a physiological salt Solution at 40 °C over 50 h with shaking at 120 cycles/min. The correlation was analyzed between the dissolution rate and each index such as carcinogenicity index (KI), nonbridging oxygen index (NBO), free energy of hydration (ΔG0) and molar ratio-weighted mean ionic radius of the alkaline earth ions as the glass network modifiers (ravg). These indexes are based on the chemical composition of the fiber. Among these chemical Indexes, KI, NBO and ΔG0 do not show any correlation with the dissolution rate of the fibers. The ravg, suggested in this study, is the only index that shows a linear correlation with the dissolution rate of the fibers. It is concluded that the ravg plays an important role as an indicator of the biosolubility of amorphous silicate fibers of this type. In addition, the ravg may be one of the indexes to classify the newer fibrous materials of this type, which are less biopersistent.