Ahmad Rahbar-Kelishami

The Effect of Size and Concentration of Nanoparticles on the Mass Transfer Coefficients in Irregular Packed Liquid–Liquid Extraction Columns

This investigation explored the effects of nanofluids on mass transfer enhancement using an irregularly packed liquid–liquid extraction column and the chemical systems of water–acetic acid–toluene. SiO2 nanoparticles with sizes of 10, 30, or 80 nm are dispersed in toluene–acetic acid to produce nanofluids with different volume fractions of 0, 0.01, 0.05, and 0.1 vol.%. The effects of nanoparticle size and concentration on dispersed phase mass transfer coefficient were discussed based on the experimental data. This is for the first time that the effect of nanoparticle size is studied in liquid–liquid extraction systems. It was found that the mass transfer enhancement was more significant in nanofluids with smaller particles. It was also observed that mass transfer coefficient is larger in nanofluids compared to that in dispersed phase without nanoparticles, with a peak enhancement at a nanoparticle volume fraction of 0.05 vol.% for 10-nm particles and 0.01 vol.% for 30- and 80-nm particles. The maximum mass transfer coefficient enhancement was approximately 42% at 0.05% concentration of nanoparticles using smaller particles (10 nm). Finally, a novel correlation for prediction of effective diffusivity in the presence of nanoparticles has been proposed, which is a function of nanoparticle size and its concentration. The main advantage of this approach is that the principal effect of these two parameters is considered in correlation without which the experimental data could not be fitted with an acceptable accuracy.

The Effect of Type and Concentration of Nano-Particles on the Mass Transfer Coefficients: Experimental and Sherwood Number Correlating

Developments in the area of nano-fluids are ongoing specifically in the area of liquid-liquid extractions in different industries. In the present study, mass transfer coefficients have been obtained experimentally in a spray extraction column in the presence of different nano-particles to develop a new correlation for the prediction of the dispersed phase Sherwood number. The results have shown that the proposed correlation can estimate the experimental drop Sherwood number with high accuracy. Also, the conceptual effect of nano-particle hydrophobicity/hydrophilicity is quantified in correlation without which the experimental data could not be fitted with an acceptable accuracy.

Zinc and nickel adsorption onto a low-cost mineral adsorbent: kinetic, isotherm, and thermodynamic studies

AbstractIn this study, adsorption of zinc and nickel ions from aqueous solutions by low-cost dolomite was investigated. Dolomite, as a mineral adsorbent, is ample in most countries of the world. Morphology of adsorbent surface and the nature of the dolomite powder were examined using the scanning electron microscope. The process has been studied as a function of contact time, pH, initial concentrations, temperature, and adsorbent dosage. The experimental data were evaluated using three isotherm and kinetic models, including the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models for kinetics and Freundlich, Langmuir and Temkin for isotherms. The results showed that the adsorption isotherm data were fitted well by the Langmuir isotherm and adsorption kinetics followed the pseudo-second-order model for both metal ions. The thermodynamic parameters, such as the change in standard free energy, enthalpy, and entropy, were also determined. The calculated parameters indicated that adsorpt...

Impacts of SiO2 and MgO nanoparticles on mass transfer performance of batch liquid-liquid extraction

ABSTRACT Due to substantial impacts of nanoparticles on mass and heat transfer, having knowledge about different types of nanoparticles can contribute to access high efficiencies. As an investigation, in the present study, a number of liquid-liquid extraction experiments were designed by the use of Taguchi design model in order to study the impacts of SiO2 and MgO nanoparticles on mass transfer, in the batch systems. Acetic acid was considered as solute in some organic phases (i.e., n-butanol, n-butyl acetate, toluene, and chloroform), and pure water was applied as solvent. Taguchi experiment design method made more precision and convenience in the work. Final results showed reduction of mass transfer yield due to the presence of two nanoparticles used in this work.

A novel approach for calculating packed column height based on new correlation of mass transfer coefficient

Abstract The calculation of column’s height plays an important role in packed columns precise design. This research is based on experimentally measurement of mass transfer coefficients in different heights of packed column to predict its height. The objective of presented work is to introduce a novel conceptual method to predict column height via new correlation for mass transfer coefficient. As the mass transfer coefficient is decreased with increase of column height, the HTU’s are not constant figures along the column so this new approach is called increasing HTU’s. The results of the proposed idea were compared with other correlations and the conventional method i.e. constant HTU’s. Since the results are in very good agreement with experimental data comparing to conventional method, it seems this approach can be a turning point in design of all differential columns like packed columns. Making use of this method is suggested for design of differential columns.