Characterization of Ag(I), Co(II) and Cu(II) removal process from aqueous solutions using dolomite powder

Ahad Ghaemi,Meisam Torab-Mostaedi,Shahrokh Shahhosseini,Mehdi Asadollahzadeh 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.1

Dolomite, a natural adsorbent, was used for removal of Ag(I), Cu(II) and Co(II) from aqueous solutions. Adsorption parameters including pH, temperature and contact time have been investigated to obtain adsorption mechanism. The results of experiments showed that adsorption of the metal ions increased by increasing pH values up to 5.5. The adsorption process was initially fast. Equilibrium isotherm data were analyzed using Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. Maximum adsorption capacity of Ag(I), Cu(II) and Co(II) was 1.34, 1.63and 2.84 mg/g at 20 oC, respectively. Kinetic models including Lagergren first-order and pseudo-second-order were used to test kinetic data. The results showed that pseudo-second-order has good agreement with experimental data. Thermodynamic parameters of the process were also investigated at different temperatures. The negative values of Gibbs free energy and enthalpy changes for Ag(I), Cu(II) and Co(II) indicated the spontaneous and exothermic nature of the adsorption process.

Optimization of lanthanum extraction in asymmetric rotation pilot plant column by using central composite methodology

Mehdi Asadollahzadeh,Rezvan Torkaman,Meisam Torab-Mostaedi 한국자원공학회 2020 Geosystem engineering Vol.23 No.2

The present work aimed to optimize the lanthanum extraction efficiency in the pilot-scale asymmetric rotating disc contactor. Optimal batch-scale extraction conditions were determined for the preparation of feed for extraction column (D2EHPA 0.08 mol/L; pH~8). In continuous mode, the optimization with the central composite design approach was performed by using three main parameters, such as continuous phase flow rate, agitation intensity, dispersed phase flow rate. Three responses studied were slip velocity, dispersed phase holdup, and extraction efficiency. The higher value of extraction efficiency for lanthanum extraction shows the main effect of agitation intensity on the dispersed phase holdup, slip velocity, and rate of mass transfer. The optimum conditions for extraction efficiency equal 98.5% were obtained at a rotation speed equal to 7.75 1/s, and phase flow rates equal to 1.25 × 10−5 m3/s. The new correlations are estimated to describe the holdup of the dispersed phase and the slip velocity with high accuracy and R-square values equal to 0.9734 and 0.9670, respectively. The results showed that the pilot plant asymmetric rotating disc column could be used as an appropriate column for the lanthanum extraction from aqueous solution as an example of rare earth metals.

Feasibility of pilot-scale disc-donut column for continuous cadmium extraction with the perspective of droplet size distribution

Asadollahzadeh Mehdi,Torkaman Rezvan,Torab-Mostaedi Meisam,Heydari Ali 한국자원공학회 2021 Geosystem engineering Vol.24 No.6

Heavy metal removal is a significant problem in various industries. Liquid-liquid extraction is a practical process in recovering these elements. In this study, the behavior of pilot-scale disc-donut column in the extraction of cadmium ions was evaluated. The effects of droplets with the variation size distributions are significant in describing performance and characteristics of an extractor for removing the substrate from aqueous or organic phases. The size distribution of droplets is relative to the interfacial area under steady conditions. To match the size distribution of droplets, the experiments are carried out in reaction and non-reaction conditions. In emulsion regime (pulsing intensity (Af), inlet organic and aqueous phase flow rate (Vc, Vd) equal to 3.3 cm/s, 2.22 mm/s, and 2.22 mm/s, respectively) and under the optimized conditions, 99.7% of the cadmium can be recovered from the aqueous solution. It was found that Weibull distribution gives the best fit at each operation mode while inverse Gaussian distribution gives the most inferior fit. According to a series of statistical analyses, it is shown that the pulsation intensity imposed more influence on drop sizes, and superficial flow rates of both phases are less able to the successful prediction of size distribution of droplets.

Testing the Implementation of a Pilot-Scale Kühni Column in Reactive and non-Reactive Condition

Asadollahzadeh Mehdi,Torkaman Rezvan,Torab-Mostaedi Meisam 한국자원공학회 2021 Geosystem engineering Vol.24 No.2

In this study, the primary efforts focused on using the Kühni extraction column with optimal energy and extraction efficiency for the removal of zinc ions from aqueous solution. The implementation of the extractive column was investigated in the reactive and non-reactive conditions. The experimental works illustrate that the extraction efficiency and hydrodynamic parameters, particularly depend on the energy input, phase flow rates as well as on the physical properties of the aqueous and organic phases. Among the operating parameters, the choice of the appropriate range for rotation speed plays a significant role for the removal of zinc ions in the pilot-scale Kühni column. The results showed that in the optimal condition for rotation speed, aqueous phase flow rate, and dispersed phase flow rate equal to 181 rpm, 33 L/h, and 21 L/h, respectively, the amount of zinc extraction reaches a maximum of 99.58%.

Study on the feasibility of using a pilot plant Scheibel extraction column for the extraction and separation of lanthanum and cerium from aqueous solution

Mehdi Asadollahzadeh,Rezvan Torkaman,Meisam Torab-Mostaedi 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.2

Batch and continuous experiments were carried out in a Scheibel extraction column to separate La(III) from Ce(III). Central composite design was used to evaluate the influence of pH, extractant concentration in the batch experiments, and the influence of rotor speed, phase flow rates in the continuous experiments. At optimum conditions (pH 3.5, D2EHPA extractant concentration 0.05 M, rotor speed 128 rpm, dispersed phase flow rate 32 L/h and continuous phase flow rate 18 L/h), high extraction efficiency and separation factor equal to 88.12% and 4.89, respectively, for cerium separation from lanthanum were reasonably well predicted by the model. At higher rotor speed, La(III) and Ce(III) ions move faster from aqueous to the organic phase, which retards the higher interaction between ions and D2EHPA extractant. The results showed that this extraction column could be a potential candidate for the extraction and separation of La(III) and Ce(III) ions or other industrial wastewater.

Adsorption ability of oxidized multiwalled carbon nanotubes towards aqueous Ce(III) and Sm(III)

Fattaneh Naderi Behdani,Alireza Talebizadeh Rafsanjani,Meisam Torab-Mostaedi,Seyed Mohammad Amin Koochaki Mohammadpour 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.2

The aim of the present work was to investigate the adsorption of Ce(III) and Sm(III) onto multiwalled carbon nanotubes (MWCNTs) oxidized with concentrate nitric acid. The effects of solution pH, adsorbent dosage, and contact time were studied by batch technique. Langmuir, Freundlich and D-R isotherms were used to describe the adsorption behavior of Ce(III) and Sm(III) by oxidized MWCNTs, and the experimental results fitted Freundlich model well. The maximum uptake capacities (qm) calculated by applying the Langmuir equation for samarium and cerium ions were found to be 89.28 and 92.59 (mg/g), respectively. A comparison of the kinetic models and the overall experimental data was best fitted by the pseudo second-order kinetic model. The calculated thermodynamic parameters (ΔGo, ΔHo, and ΔSo) showed that the adsorption for Ce(III) and Sm(III) is feasible, spontaneous and exothermic at 30-60 oC. Moreover, more than 70% of Ce(III) and Sm(III) adsorbed onto Oxidized MWCNTs could be desorbed with HNO3.

Reactive extraction evaluation for vanadium (V) removal in the MRDC column using axial dispersion and central composition approach

Benyamin Shakib,Mehdi Asadollahzadeh,Mohamamd Outokesh,Rezvan Torkaman,Meisam Torab-Mostaedi 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.12

Reactive extraction development was investigated to extract vanadium ions from sulfate solution in the modifiedrotating disc column (MRDC). It was found from batch experiments that D2EHPA and TBP concentrations, initialaqueous phase pH, and the concentration of NH4OH as a stripping agent were optimized equal to 0.3M, 0.36 M, 2, and1M, respectively. In the continuous experiments, the effects of rotor speed, aqueous and organic phase flow rates, andmass transfer direction were investigated on the dispersed phase holdup, mass transfer coefficients, and vanadiumextraction. The experiment design was based on the response surface design to analyze the dependence of responseswith the input parameters. The uncertainty analysis by the Monte Carlo simulation indicates that the rotor speed, reactionconditions, and phase flow rates affected the dispersed phase holdup. By applying the axial dispersion model, theperformance of mass transfer coefficients in terms of agitation speed, aqueous phase flow rate, organic phase flow rate,and mass transfer direction was evaluated under the chemical reaction system. A new model by considering the dimensionlessnumbers has been provided to predict overall mass transfer data based on the dispersed phase.