Modeling of Precipitation in Reverse Micellar Systems

Abstract

A model of the precipitation process in reverse micelles has been developed to calculate the size of fine particles obtained therein. While the method shares several features of particle nucleation and growth common to precipitation in large systems, complexities arise in describing the processes of nucleation, due to the extremely small size of a micelle and of particle growth caused by fusion among the micelles. Occupancy of micelles by solubilized molecules is governed by Poisson statistics, implying most of them are empty and cannot nucleate of its own. The model therefore specifies the minimum number of solubilized molecules required to form a nucleus which is used to calculate the homogeneous nucleation rate. Simultaneously, interaction between micelles is assumed to occur by Brownian collision and instantaneous fusion. Analysis of time scales of various events shows growth of particles to be very fast compared to other phenomena occurring. This implies that nonempty micelles either are supersaturated or contain a single precipitated particle and allows application of deterministic population balance equations to describe the evolution of the system with time. The model successfully predicts the experimental measurements of Kandori et al. 3 on the size of precipitated CaCO3 particles, obtained by carbonation of reverse micelles containing aqueous Ca(OH)2 solution.

New Trends on the Synthesis of Inorganic Nanoparticles Using Microemulsions as Confined Reaction Media

“…Bandyopadhyaya et al (Bandyopadhyaya et al, 1997) (Chew et al, 1990) have studied the effect of alkanes in the formation of AgBr particles in ionic W/O microemulsions (using AOT as surfactant), where the transmittance of the reactions were followed with time with UV-Vis and Stopped-Flow Spectrophotometry. They have found an increase on reaction rate with the chain lenght of the alkane.…”

Calcium carbonate phase transformations during the carbonation reaction of calcium heavy alkylbenzene sulfonate overbased nanodetergents preparation

“…Although there is some difference in compositions of HAB from different sources, it is confirmed that they are mainly composed of dialkylbenzene and monoalkylbenzene with paraffinic side chains ranging from C 11 to C 22 , a small amount of other aromatic derivatives such as diphenylalkane and dialkyltetralin analyzed by Fourier transform infrared spectroscopy (FTIR) [5], gas chromatography and mass spectrometry (GC/MS) techniques [6][7][8]. It is believed that synthetic sulfonates are an important outlet for utilizing HAB byproducts with high additional value and the heavy alkylbenzene sulfonate (HABS) is evaluated as a starting material for preparing overbased sulfonate detergents [8][9][10].…”

Reduced discrete population balance model for precipitation of barium sulfate nanoparticles in non-ionic microemulsions

“…With respect to the last aspect, these models (see overview in [28]) can be classified into two groups, namely stochastic models [29][30][31][32][33][34][35][36][37] which comprehend stochastic population balance equations, Monte-Carlo simulation models, and deterministic models [10,15,19,[38][39][40] where the latter comprise population balance models, moment models and simple analytical solutions. The main difference between models of the two groups lies in the complexity which is taken into account to achieve a solution at reasonable computational effort.…”