Sujata Mishra

Solvent extraction of neodymium(III) from acidic nitrate medium using Cyanex 921 in kerosene

Abstract The extraction of neodymium(III) from acidic nitrate medium was investigated using Cyanex 921 as extractant in kerosene. The metal concentration in the aqueous phase before and after extraction was determined spectrophotometrically by Arsenazo III method. The complete equilibration was achieved in 15 min. The effects of shaking time, nitric acid concentration, nitrate concentration, extractant concentration, and temperature on the extraction were studied. The extraction of Nd(III) was found to increase very slowly with increase in concentration of HNO 3 in the range of 0.001–0.008 mol/L and then decreased when 0.01 mol/L HNO 3 was used. The percentage of extraction was increased with increase in nitrate concentration from 0.01–0.45 mol/L and then decreased when nitrate concentration increased to 0.5 mol/L. Quantitative extraction of Nd(III) (98%) was obtained from the aqueous phase containing 0.001 mol/L HNO 3 and 0.1 mol/L KNO 3 using 0.5 mol/L Cyanex 921. On the basis of slope analysis, the extracted complex in the organic phase was proposed to be Nd(NO 3 ) 3 .2Cyanex 921. The extraction of Nd(III) was found to increase with increase in concentration of metal ion in the range of 0.001–0.05 mol/L from 0.001 mol/L HNO 3 and 0.1 mol/L KNO 3 with 0.1 mol/L Cyanex 921. The percentage of extraction of neodymium was found to decrease with increase in temperature. From temperature variation studies, the negative value of Δ H indicated the extraction reaction to be exothermic and the negative value of Δ S indicated the formation of a stable complex. Almost 100% Nd(III) was recovered from the fully loaded organic phase using 0.002 mol/L H 2 SO 4 and 0.01 mol/L HCl.

A mathematical model of MHD nanofluid flow having gyrotactic microorganisms with thermal radiation and chemical reaction effects

In this article, we have examined three-dimensional unsteady MHD boundary layer flow of viscous nanofluid having gyrotactic microorganisms through a stretching porous cylinder. Simultaneous effects of nonlinear thermal radiation and chemical reaction are taken into account. Moreover, the effects of velocity slip and thermal slip are also considered. The governing flow problem is modelled by means of similarity transformation variables with their relevant boundary conditions. The obtained reduced highly nonlinear coupled ordinary differential equations are solved numerically by means of nonlinear shooting technique. The effects of all the governing parameters are discussed for velocity profile, temperature profile, nanoparticle concentration profile and motile microorganisms’ density function presented with the help of tables and graphs. The numerical comparison is also presented with the existing published results as a special case of our study. It is found that velocity of the fluid diminishes for large values of magnetic parameter and porosity parameter. Radiation effects show an increment in the temperature profile, whereas thermal slip parameter shows converse effect. Furthermore, it is also observed that chemical reaction parameter significantly enhances the nanoparticle concentration profile. The present study is also applicable in bio-nano-polymer process and in different industrial process.

Extraction of Zr(IV) from hydrochloric acid with tri-octyl amine and Cyanex 921 in kerosene

This article reports the extraction of zirconium (IV) from aqueous HCl solution by tri-octyl amine (TOA), Cyanex 921, and their binary mixture using kerosene as the diluent. The effect of some parameters on the extraction of Zr(IV) was investigated such as equilibration time, aqueous phase acidity, extractant molarity, chloride ion concentration, nature of diluents, and temperature. The extraction of Zr(IV) was found to be 99% from 7.5 M HCl using the mixture of extractants containing 0.1 M TOA and 0.02 M Cyanex 921 in kerosene. Kerosene was found to be the effective diluent for the extraction of Zr(IV) with the binary mixture of TOA and Cyanex 921. The positive enthalpy change and positive entropy change in the binary extraction system show the endothermic process with an increase in entropy. Stripping of Zr(IV) from the loaded organic phase containing the mixture of TOA (0.1 M) and Cyanex 921 (0.02 M) indicates that HNO3 and Na2CO3 are the best stripping agents.

Investigation on molecular interaction studies of binary mixture of DEHPA and petrofin at 298.15 K

ABSTRACT The present article reports the values of density (ρ12), molar volume (V12), apparent molar volume (Vɸ), dielectric constant (ϵ12), molar polarisation (P12) and molar refraction (R12) of binary mixture of di-2-ethylhexyl phosphoric acid (DEHPA) and petrofin at various compositions. The excess properties such as VE, ϵE, ΔnD, PE and RE have been calculated to throw light on the existence of interaction between the DEHPA and petrofin molecules in the binary mixture. The values of VE and RE were found to be positive while the values of ϵE, ΔnD and PE were negative over the entire composition showing weak interaction between the two unlike molecules in the mixture. The Kirkwood-correlation factors (g) have been evaluated to know the nature of interaction prevailing in DEHPA and petrofin. These data provide useful information regarding interaction between self-associated protic DEHPA and non-associated petrofin which in turn helps the metallurgist to use DEHPA diluted with petrofin as effective solvent in extraction of metals.

Studies on solvent extraction of La(III) using [A336][NO3–] and modeling by statistical analysis and neural network

ABSTRACT Solvent extraction of La(III) from acidic nitrate medium has been studied with [A336][NO3–] in kerosene. The factors affecting the extraction of La(III) like equilibration time, nitrate ion, extractant and La(III) concentrations, aqueous acidity, O/A ratio variation, nature of diluent, and temperature have been investigated. McCabe-Thiele diagram has been plotted to find out the actual number of theoretical stages needed for complete extraction of lanthanum. The solvent has been successfully regenerated for further use after stripping of the metal. IR studies of [A336][NO3–] and La(III) loaded [A336][NO3–] have been carried out. Modeling of extraction data has been done using Multiple linear regression analysis and Artificial Neural Network, and the performances have been compared. Error in each case was evaluated in terms of R2 and Root mean squared error (RMSE). Maximum extraction of La(III) was 82% when 0.6 M [A336][NO3–] was used for extraction. About 98% of the metal has been recovered using 0.2 M HNO3 as stripping agent. Extractive separation of La(III) and Sm(III) was maximum (β = 65.2) using 0.1 M [A336][NO3–]. IR studies revealed formation of lanthanum complex in the extraction process. Artificial Neural Network proved to be better over Multiple linear regression in data prediction.

Studies on liquid–liquid extraction of La(III) from acidic nitrate medium using TBP in petrofin

The present study aims at investigating the capability of tri-n-butyl phosphate (TBP) in petrofin as extracting agent for La(III) from acidic nitrate medium. The concentrations of TBP and sodium nitrate have positive influence while temperature shows a negative impact on the extraction. The values of standard enthalpy change and entropy change confirm the extraction process as exothermic with a decrease in randomness due to complexation. Regression analysis results fit well with the experimental data in the cases of TBP and nitrate concentration variation.

Synergistic extraction and separation studies of Ce(III) from acidic nitrate medium using binary mixture of Cyanex 921 and Cyanex 923 in kerosene

ABSTRACT The effect of parameters like shaking time, nitric acid, nitrate ion, extractant concentration, temperature, diluents, and phase volume ratio on the extraction of Ce(III) from acidic nitrate medium using binary mixture of Cyanex 921 and Cyanex 923 in kerosene has been investigated. Synergism was observed in the range 0.001-1.0 mol/L HNO3. With increase in extractant concentration and O/A phase volume ratio, extraction increases while with increase in nitric acid concentration and temperature, extraction decreases. Sulphuric acid and hydrochloric acid are found to be effective in stripping. Separation factors for Nd/Ce are higher as compared to those for Ce/La and Pr/Ce.

Effect of Radiation on MHD Free Convective Flow over a Stretching Sheet in the Presence of Heat Source/Sink

In this analysis, effects of viscous dissipation and thermal radiation on an electrically conducting boundary layer flow, heat and mass transfer of a fluid through a porous medium over a stretching sheet in the presence of heat source/sink is considered. The symmetry groups admitted by the corresponding boundary value problem are obtained by using symmetric transformations. These transformations are used to convert the partial differential equations of the governing equations into self-similar non-linear ordinary differential equations. These transformed ODEs are solved by employing Runge-Kutta fourth order with shooting method. Numerical results obtained for different thermo-physical parameters characterizes the flow phenomena are drawn graphically and effects of various physical parameters on velocity, temperature and concentration profiles are discussed. Numerical computation for skin friction, Nusselt number and Sherwood number are also obtained and presented in Tables.