Influence of NH4Cl on Hydrothermal Formation of α-CaSO4·0.5H2O Whiskers

الملخص EN

The influence of NH4Cl on hydrothermal formation of CaSO4·0.5H2O whiskers from CaSO4·2H2O precursor at 135°C was investigated in this paper.

Compared with the blank experiment, the presence of 3 × 10−2 mol·L−1 NH4Cl led to the increase of the lengths of the whiskers from 50 to 160 μm to 150 to 300 μm and the decrease of the diameters from 1.0 to 1.5 μm to 0.2 to 0.5 μm.

The dissolution of CaSO4·2H2O was accelerated by the complex interactions with NH4Cl and the soluble cations, which led to the decrease of the induction time for the occurrence of α-CaSO4·0.5H2O from 46 minutes to 34 minutes and the formation of CaSO4·0.5H2O whiskers with high aspect ratios.

Furthermore the critical supersaturation for the formation of α-CaSO4·0.5H2O was investigated.