The mechanism of particle formation during homogeneous precipitation of zinc sulfide

Abstract

Monodisperse zinc sulfide particles were prepared by homogeneous precipitation from zinc sulfate solutions. Particle size could be adjusted in the range of 1 to 5 microns by changing the viscosity of the reaction medium. From electron micrographs of particles prepared in high viscosity media subparticles up to 50 nm in diameter could be observed. From these results it was concluded that particle growth took place predominantly by Brownian coagulation.Furthermore, it was established that stirring the reactor content during the initial phase of particle formation alone did not influence particle size, nor did it promote coagulation of micron-sized spheres. We were able to prepare this material in amounts up to 2 kg of solid material from a reactor with a working volume of 36 1.

Synthesis of zinc sulfide multi-scale agglomerates by homogeneous precipitation–parametric study and mechanism

“…Thus information on the experimental conditions throughout the Table 3 Effect of parameters on scale transition (as reported by Refs. [8,9]). whole experiment would be necessary to propose a mechanism for the precipitation process especially as regards its morphological aspects.…”

“…[8,9] (Table 3). Although these authors express the effect of the parameters on different transitions, certain similarity exists with our results, except for the pH effect on the largest sizes.…”

“…Its intervention in the agglomeration dynamics is not evident. Actually, hydrodynamics is able to account for three successive agglomerate scales, however not for four as assumed within the mechanism of Eshuis and Koning [8] and Eshuis et al [9].…”

“…In particular the relatively basic geometry of the reactors did not allow a real determination of the influence of stirring. Only Eshuis and Koning [8] and Eshuis et al [9] performed a systematic study of the dependence of the agglomerate morphology on the experimental parameters and proposed the most advanced mechanism of ZnS multi-scale agglomeration ever presented so far. The four steps of the mechanism (1)-(4) are represented in Fig.…”

“…Experimental works on ZnS homogeneous precipitation use an acid solution of zinc acetate, nitrate, chloride or sulfate and thioacetamide (CH 3 CSNH 2 ) as initial medium [3][4][5][6][7][8][9]. Thiocetamide (TAA) is currently used as a hydrogen sulfide source in different organic syntheses.…”