Zinc 2 acetate dehydrate

Copper(II) acetate monohydrate (4 mg ml -1 ) and zinc(II) acetate dehydrate (2.16 mg ml -1 ) (Sigma Aldrich ≥99% Puriss), were dissolved in ethanol (reagent grade, Fischer Scientific) containing 0, 5 or 10 vol% deionized water. Smithsonite ZnCO3 was prepared with zinc(II) acetate dehydrate (2.16 mg ml -1 ) in a 10 vol% water and ethanol solution. Supercritical anti-solvent (SAS) experiments were performed using apparatus manufactured by Separex. CO2 (BOC) was pumped through the system (held at 110 bar, 40 °C) via the outer part of a co-axial nozzle at a rate of 6 kg h -1 . The metal salt solution was concurrently pumped through the inner nozzle, using an Agilent HPLC pump at a rate of 6.4 ml min -1 .
The resulting precipitate was recovered on a stainless steel frit, while the CO2-solvent mixture passed down stream, where the pressure was decreased to separate the solvent and CO2. The precipitation vessel has an internal volume of 1L. Precipitation was carried out for 120 min followed by a purge of the system with ethanol-CO2 for 15 min then CO2 for 60 min under 110 bar and 40 °C. The system was then depressurised and the dry powder collected. Recovered samples were placed in a vacuum oven at 40 °C for 4 h to remove any residual solvent. Approximately 1.5 g of georgeite is prepared during the 120 min duration of solution precipitation.