Dr Roberto Moreno-Atanasio

© 2015 American Chemical Society.Polyamine-derived silica particles are proposed to grow due to primary particle (<25 nm) aggregation. On the basis of material balance, we propose an aggregation model to predict the kinetics of polyamine-derived silica formation. The model is based on a rate equation consisting of two terms, representing both the production and aggregation of primary particles. The modeled rate constants were found to be a function of the concentration of silica precursor and biomimetic catalyst. Our experimental results agree with our model and suggest that the cube root of the silica precursor concentration is linearly proportional to particle diameter, as well as that below a critical concentration (~25 mM) no particles will be formed. If the concentration of reagents was high enough to produce particles with diameters greater than ~350 nm, other populations of particles, each of them growing at different rates, were necessary to describe the overall particle diameter observed, which was modeled as the average diameter of these different populations.

© 2016 The Institution of Chemical Engineers.Fine coal may be separated from an aqueous suspension of coal and mineral particles through the application of a pure oil. The pure oil preferentially wets and agglomerates only the coal, forming a high quality, granular product. However, the use of the pure oil also comes at a relatively high cost and this cost prohibits commercial implementation of this process. In this work a new, economic binder, was introduced. This binder consisted of a high internal phase water-in-oil emulsion which was 95. vol% water and 5. vol% organic. This type of binder was selected as it possessed the hydrophobic surface functionality of oil while the space filling functionality of the binder was primarily satisfied by the dispersed water droplets within the emulsion. The application of this emulsion in the agglomeration process led to a 10-fold reduction in the organic liquid dosage required to achieve agglomeration as compared a pure oil binder. It was also observed that the agglomeration time required when using the emulsion binder was one order of magnitude less than required when using a pure oil binder. This variation was considered to result from the five orders of magnitude difference in the viscosity of the two binders.

© 2014 American Chemical Society.A high internal phase (HIP) water-in-oil emulsion was used as the binder in the selective agglomeration of fine coal from an aqueous suspension of coal and mineral particles. Traditionally, this agglomeration is achieved by a pure oil, hydrophobic, binder. However, the high cost associated with using pure oil makes the process economically unfeasible. Therefore, the emulsion binder introduced in this work was motivated by the economic need to reduce the amount of organic liquid required in the process. The effect of the agitation time during the agglomeration process and the composition of the emulsion on its performance as a binder were investigated. The best result obtained was for a HIP emulsion made from 3 wt % aqueous NaCl and diesel oil with sorbitan monooleate as the emulsifier. This emulsion had a dispersed phase volume fraction of 0.94 and achieved a 7.5-fold reduction in the amount of organic liquid required to achieve agglomeration.

Numerical simulations have been carried out to investigate the formation and motion of single bubble in liquids using volume-of-fluid (VOF) method using the software platform of FLUENT 6.3. Transient conservation mass and momentum equations with considering the effects of surface tension and gravitational force were solved by the pressure implicit splitting operator (PISO) algorithm to simulate the behavior of gas-liquid interface movements in the VOF method. The simulation results of bubble formation and characteristics were in reasonable agreement with experimental observations and available literature results. Effects of fluid physical properties, operation conditions such as orifice diameter on bubble behavior, detachment time, bubble formation frequency and bubble diameter were numerically studied. The simulations showed that bubble size and bubble detachment times are linear functions of surface tension and decrease exponentially with the increase in liquid density. In contrast, only a small influence of the fluid viscosity on bubble size and detachment time was observed. Bubble collapse at a free surface simulation with VOF method was also investigated. © 2014 Korean Institute of Chemical Engineers, Seoul, Korea.

High-resolution dynamic light scattering (DLS), scanning electron microscopy (SEM), time-lapse photography, and attenuated total reflectance Fourier transform infrared spectroscopy were used to analyze the growth kinetics of polyethyleneimine (PEI)-silica particles fabricated from the condensation of hydrolyzed trimethoxymethylsilane (TMOMS) and PEI/phosphate buffer (PEI/PB). Depending on the concentration of hydrolyzed TMOMS and PEI/PB, three stages were identified. We observed the existence of a nucleation time that has never been reported in the literature when TMOMS has been used. During this nucleation time, particles of less than 25 nm were detected using in situ DLS measurements taken every 15 s (high resolution), a DLS time-scale resolution not previously reported. In addition, the length of the nucleation time depended mainly on the PEI/PB concentration, but also TMOMS concentration. The growth stage was evident from the rapid increase of particle size with time. Due to the high resolution of the DLS measurements, a peak could be observed in the particle diameter during particle growth, which corresponds to a secondary population of particles required for the larger particles to further increase in size. Finally, during the equilibrium region, particles reached their maximum diameter that was independent of the concentration of PEI/PB and only changed with concentration of hydrolyzed TMOMS. © 2014 Springer-Verlag Berlin Heidelberg.

This study was concerned with the interaction between a gaseous dispersion of fine particles travelling in the horizontal direction and discrete drops of water falling vertically through the dispersion. A simple analytical model of the particle-drop collision was developed to describe the particle recovery by the drops as a function of the water flux, covering two extremes of relative velocity between the particles and drops. The Discrete Element Method was used to validate the analytical model. Further validation of the model and insights were obtained through experimental studies. The physical process of wetting was observed to be important in influencing the tendency of particles to become engulfed by the drops of water, or to either adhere to the drops or by-pass the drops altogether. Hydrophilic particles were readily engulfed while hydrophobic particles, at best, adhered to the surface of the drop, or failed to attach. Moreover, the recovery of the hydrophilic silica particles was significantly higher than the recovery of hydrophobic coal particles, with the selectivity ratio approximately 1.5. Spherical ballotini particles were the most sensitive, with a notable increase in recovery when cleaned, and evidence of increased recovery with increasing particle size. The recovery of irregular shaped silica flour particles, however, was largely independent of the particle size. A similar result was observed for irregular coal particles, though the recoveries were all lower than relatively more hydrophilic ballotini or silica flour. Crown Copyright © 2014.

Copyright 2015, Society of Petroleum Engineers.The objective of this paper is to present a co-precipitation technique with calcium carbonate for removal of heavy metals ions from oil field brine. Metals such as Mercury, Copper and Lead can be removed by the co-precipitation technique. In this work, parameters such as pH, injection time and concentration of reactants were optimized in other to obtain maximum removal efficiency. The results showed that pH has a significant effect while the injection time and reactant concentrations were less effective to remove the metals. Based on the SEM, ICP and hydrometer analysis, the optimum experimental conditions were the pH of 10, the injection time of 20 min and the reactant concentration of 0.5 mol percent. Approximately, more than 90 percent of mercury, lead and copper was removed employing co-precipitation techniques with calcium carbonate. Scanning Electron Microscopy analysis indicates that 200 rpm is the optimum rotational speed which leads to the formation of small particles. Finally, this study showed especially that the co-precipitation technique is a good alternative to remove the heavy metals especially mercury from the contaminated oil field brine.

Recent findings on the influence of single-particle properties on the bulk behaviour of dense particulate assemblies are analysed by using computer simulations based on 3-D Distinct Element Method (DEM). The micromechanical behaviour of dense systems depends on the ability of the particles to deform along the normal and tangential directions on the contact plane, i.e., the values of normal and tangential particle contact stiffnesses. In the present study, we investigate the effect of the stiffness ratio, at the macroscopic and microscopic scales, on the behaviour of three systems subjected to quasi-static shearing. These three systems are made of sphere, oblate and prolate particles, respectively. We show that, the variation in the contact stiffness ratio affects the micromechanical characteristics of non-sphere particulate systems more dominantly than the sphere particulate systems. Hence, attention must be paid to measure both the normal and tangential contact stiffnesses when characterising non-sphere fine particulates to estimate their assembly strength characteristics during shearing. © 2006 Civil-Comp Press.