Ultrahigh purity CaCO3 whiskers derived from the enhanced diffusion of carbonate ions from a larger liquid–gas interface through porous quartz stones

Abstract

A larger liquid–gas interface area during the carbonation process for preparing high-purity aragonite CaCO₃ whiskers by using porous quartz stones was developed. The presence of plenty of open pores ranging from 0.02 to 0.20 mm inside the porous quartz stones could disperse CO₂ gas in Ca(OH)₂ suspension into tiny bubbles, with an average diameter ranging from 0.28 to 3.05 mm and a large liquid–gas interface area ranging from 3571.4 to 327.9 mm², respectively, which could enhance the diffusion effect of CO₂ molecules and the uniformity of carbonate ions in the system. Thus, a uniform and low supersaturation was obtained, improving the growth of CaCO₃ whiskers. The prepared CaCO₃ whiskers showed the highest purity of 99.7%. The formation mechanism of ultrahigh purity CaCO₃ whiskers was also studied in detail. Then, the prepared CaCO₃ whiskers were introduced into a PVC matrix to study their effect on the tensile strength of PVC, and the results showed that the tensile strength was enhanced by 46.4% with 5 wt% whiskers. This method provides an effective way to enhance the performance of inorganic crystals.