Synthesis of basic zinc carbonate by solid-state reaction at room temperature

Using zinc sulfate heptahydrate (ZnSO ₄·7H ₂O) and ammonium bicarbonate (NH ₄HCO ₃) as raw materials and a template of polyethylene glycols (PEG-400), zinc carbonate (ZnCO ₃) and basic zinc carbonate (ZnCO ₃·3Zn(OH) ₂·H ₂O, BZC) powders were synthesized by the solid-state reaction at room temperature. The effects of PEG-400 dosages and the mole ratio x of NH ₄HCO ₃ and ZnSO ₄·7H ₂O on the phases of products were investigated by XRD and quasi -quantitative content analysis method. The template mechanism of reaction synthesis of ZnCO ₃ and BZC is summarized. The results show that a template is formed via PEG-400 enwrapping ZnSO ₄·7H ₂O particles, the thickness of PEG-400 template dominates the micro mechanism of solid-state reaction, where single direction diffusion for thin film and mutual diffusion for thick film take place. It is the acidity or alkalinity at local reaction zone that strongly affects the phases of products, the acidity inhibits the hydrolyzation of ZnCO ₃, while the alkalinity accelerates the hydrolyzation of ZnCO ₃ to form BZC. On this base, BZC powders were prepared by the solid-state reaction with parameters of higher x (x=3.0) and lower PEG-400 dosage (70 μL).