Open AccessSolventless Mechanochemical Synthesis of Phase Pure Syngenite
Author(s) -
Schiefer Christopher,
Plank Johann
Publication year - 2021
Publication title -
chemistry ‐ methods
Language(s) - English
Resource type - Journals
ISSN - 2628-9725
DOI - 10.1002/cmtd.202000064
Subject(s) - gypsum , materials science , crystallization , chemical engineering , nucleation , precipitation , anhydrite , phase (matter) , thermogravimetry , potassium hydroxide , chemistry , organic chemistry , metallurgy , physics , meteorology , engineering
Syngenite (K 2 Ca(SO 4 ) 2 ⋅ H 2 O) presents an effective hydration activator (accelerator) for anhydrite (CaSO 4 ) applied in construction systems. The current synthesis relies on co‐precipitation of K 2 SO 4 and CaSO 4 ⋅ 2H 2 O and produces large amounts of waste water holding excess amounts of potassium sulfate. Therefore, this method is deemed ineffective, uneconomical and environmentally unfriendly. Moreover, it produces large crystals (ℓ ∼5‐30 μm) which are less effective as nucleation seeds for gypsum crystallization. In this study, a novel, solventless mechanochemical process is proposed as a simple, eco‐friendly and reproducible method for large‐scale production of sub‐micrometer sized syngenite crystals of different morphology in high purity which strongly promote anhydrite hydration to gypsum. Optimal conditions for the mechanochemical synthesis were determined, and products obtained were characterized via X‐ray diffraction, IR spectroscopy, thermogravimetry and SEM imaging. The optimized mechanochemical product was compared with syngenite from co‐precipitation, the structural differences are discussed and its superiority as seeding material was evidenced.