Preparation of flaky dihydrate zinc oxalate particles by controlled chelating double-jet precipitation

Well-dispersed flaky ZnC2O4 center dot 2H(2)O particles were synthesized via a controlled double-jet precipitation process from the relatively concentrated solutions of Zn(NO3)(2) (0.05 mol/L) and Na2C2O4 (0.06 mol/L) in the presence of sodium citrate. The effects of concentration of the reactants, reaction time, pH values and feeding rates on the size and shape of the final particles are investigated. It was found that as-prepared dihydrate zinc oxalate particles are formed by aggregation of tiny microsized subunits, and the feeding rate as well as the citrate concentration is quite key to the morphological evolution of the hydrate zinc oxalate particles. Based on experimental results and the thermodynamic equilibrium calculation, it is confirmed that the presence of citrate ligand plays essential roles to the whole precipitation process, which may play the multiple roles of controllable release of zinc ions, crystal habit tunning agent, and dispersing surfactant. The controllable synthesis idea of well-dispersed particles in present research work has the potential of extensive application in the preparation of other similar particles. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.