Chemical resistance of the moulding of saponite/acriflavine complex after carbonization

Abstract

Powders of saponite/acriflavine complex (SAC) saponite/carbon black mixture (SKM) and saponite itself (Sap) were pressed into small discs (20 mm diameter × 3 mm), followed by heat treatment at 1073 to 1473 K under nitrogen or argon. Their chemical resistance to 10% NaOH, conc. HCl, conc. HNO₃ and conc. H₂SO₄ solutions at room temperature was examined on the basis of weight loss. The resistance of the three samples to NaOH solution was found to increase with increasing heat-treatment temperature, and both SAC and Sap after heating to 1473 K exhibited only a slight weight loss even after soaking for 20 d. On the whole, SAC had the highest resistance among three. The three samples were more resistant to acid solutions than NaOH, the resistance of both SKM and Sap increasing with increasing heat-treatment temperature. The amorphous component and forsterite crystal in the samples after heating to high temperature were preferentially attacked by NaOH and acid solutions, respectively. These results are discussed on the basis of X-ray diffraction, SEM observation, carbon content, etc.