Achieving precise morphological control in the conversion of industrial gypsum to calcium sulfate whiskers (CSWs) is a key challenge for high-value recycling. This work presents a strategy using imidazole ionic liquids to regulate the crystallization of phosphate dihydrate (DH). The study examines the microkinetics under varying supersaturation and systematically evaluates the regulatory effects of these additives, supported by density functional theory (DFT) simulations. The ionic liquids are shown to promote the growth of uniform, high-aspect-ratio CSWs. Mechanistically, DFT reveals a unique cooperative adsorption mechanism on the (010) plane of DH, where synergistic anion and cation interactions inhibit lateral growth and accelerate one-dimensional elongation. The efficacy is linked to the molecular structure, with 1-butyl-3-methylimidazolium chloride (BMIMCl) performing best due to its longer alkyl chain. These findings offer a fundamental basis for developing efficient crystal growth modifiers for gypsum-based materials.
Yang et al. (Mon,) studied this question.