Predicting the dissolution rate constant of mineral wool fibers from fiber composition.

OBJECTIVE

We developed predictive formulae for the dissolution rate constant k of acid-soluble synthetic vitreous fibers (SVF), paralleling our earlier work with glass wools, which are typically more soluble at neutral pH. Developing simple models for predicting the k of a fiber can allow prediction of behavior, aid fiber developers, and potentially reduce testing.

METHODS

The k of several acid-soluble SVF were determined using high simulant fluid flow/fiber surface area (F/A) conditions a single-fiber measurement system. Four fluids were employed, varying in base composition and citrate levels. Equations predicting the k were derived from fiber chemistry and dissolution measurements for two of the fluids.

RESULTS

Testing of several fibers showed a ∼10× increase in the k when citrate was included in the simulant solution. Data from tests with Stefaniak's citrate-free Phagoloysosmal Simulant Fluid (PSF) yielded k values aligned with expectations from results, unlike results from citrate-containing modified Gamble's solution. Predictive equations relating fiber chemistry to k showed reasonable agreement between the measured and predicted values.

CONCLUSIONS

Citrate inclusion in the solution under high F/A conditions significantly increased the measured k. This resulted in more biorelevant data being obtained using the PSF fluid with the high F/A method used. The developed predictive equations, sufficient for fiber development work, require refinement before a recommending their use in place of biopersistence testing. Significant fit improvements are possible through additional measurements under these experimental conditions.