Effect of Ionic Surfactants and Alcohols on the Morphology of CuSO4·5H2O Crystals: Combined Use of Factors and Significance of Threshold Surfactant Concentration

Formation and Phase Transformation of MgCO3·3H2O Whiskers in the Presence of Sodium Dodecyl Sulfate

Huge amounts of MgCl₂·6H₂O are produced annually as a byproduct or waste from KCl production in the Qinghai province of China. An ecological and economic way to solve this problem is transforming the abandoned MgCl₂·6H₂O to valuable MgCO₃·3H₂O whiskers. The formation and phase transformation of MgCO₃·3H₂O whiskers were studied in the crystallization process, in which MgCl₂ and NH₄HCO₃ were precipitated in the presence of sodium dodecyl sulfate (SDS) at 50 °C. Results showed that porous spherical MgCO₃·3H₂O, MgCO₃·3H₂O whiskers, and flocculent rod-like 4MgCO₃·Mg(OH)₂·4H₂O were formed with decreasing concentration of SDS as the crystallization proceeded. When the concentration of SDS was lower than the critical micellar concentration (6.5 mmol·L^-1) at 60 min, SDS was beneficial for the growth in the [010] direction to form one-dimensional MgCO₃·3H₂O whiskers with a high aspect ratio, good uniformity, and a smooth surface (length, 60-70 μm; aspect ratio, 110-140).

Effect of urea additives on CuSO4·5H2O crystal habit: an experimental and theoretical study

Oblique hexagonal prism copper(ii) sulfate pentahydrate crystal was formed due to the preferential adsorption of urea molecules on specific faces.