Influence of the process parameters on the formation of CaSO 4·0.5H2O whiskers

Abstract

This paper discussed the influence of the process parameters such as the temperature, the mixing ways, and the molar ratios of the reactants on the morphology of the CaSO4·2H2O precursors and the CaSO4·0.5H2O whiskers. The experimental results indicated that CaSO4·0.5H2O whiskers with a length of 80-310 m and a width of 0.8-8.0 m were produced at hydrothermal condition, using CaSO4·2H2O fine particles as the precursors which were formed by adding Na2SO4 solution into CaCl 2 solution at 25°C at the molar ratio of Na2SO 4 to CaCl2 being 0.5: 1. A lower supersaturation and a higher [Ca2+]/[ S O 4 2 - ] molar ratio favored the formation of CaSO4·2H2O particles with small sizes and the hydrothermal synthesis of CaSO4·0.5H2O whiskers with high aspect ratios. © 2013 Kangbi Luo et al.