Dissolution of CaSO4·1/2H2O and precipitation of CaSO4·2H2O: A kinetic study by synchrotron X-ray powder diffraction

摘要: Abstract Time-resolved X-ray powder diffraction has been performed on hydrating samples of calcium sulfate hemihydrate with 0.50 wt.% dihydrate seeds added. Data were recorded in transmission mode using a position sensitive detector and synchrotron radiation optimised intensity (wavelength 1.4 A). The dissolution the formation both monitored. Varying water/solid weight ratio (w/s) from to 1.50 did not affect reaction rate significantly. Addition potassium water accelerates 0.25 citric acid monohydrate causes retardation; times for complete reaction: 17 42 min, respectively, compared 28–32 min without additive (w/s=1.00). A comparison curves shows (i) that dissolves precipitates at same rate, (ii) preferred orientation effects are absent experiments.