Control Preparation of Zinc Hydroxide Nitrate Nanocrystals and Examination of the Chemical and Structural Stability

We have investigated the control preparation and aqueous stability of a potential suspension fertilizer: zinc hydroxide nitrate. We have observed that this compound can be synthesized by quick precipitation of zinc nitrate in sodium hydroxide solution under various conditions, whereas it can also be readily transformed to more stable Zn(OH)2 or ZnO at pH >6.5 and aged at 50 °C. The transformation from zinc hydroxide nitrate to Zn(OH)2 and ZnO has been examined with XRD/FTIR/SEM techniques and discussed in detail, presumably involving the formation and dissociation of the intermediate solution species [Zn(OH)4]2–/[Zn(OH)3]−. We have also found that as-prepared zinc hydroxide nitrate crystals are very stable when they are isolated and then dispersed in aqueous solution with pH 5–9 while slightly dissolved to give zinc ion concentration of 30–50 mg/L. Such aqueous stability and solubility have thus suggested that this compound can be used as a long-term zinc foliar fertilizer of various crops.