Mathematical modeling for facilitated transport of Ge(IV) through supported liquid membrane containing Alamine 336

A mathematical model was developed for the germanium facilitated transport from a medium containing tartaric acid using Alamine 336 as a carrier. Modeling was carried out based on the extraction constant (Kext) obtained from the liquid-liquid extraction (LLX) modeling. The LLX data was achieved from experiments with conditions being Alamine 336 concentrations of 0.1-10 %v/v from a solution containing about 1.378 mmol/L Ge (100 mg/L) and tartaric acid as an anionic complexant. The LLX model was attained using the equilibrium-based procedure and fitted to extraction experimental data for various carrier concentrations. This model presented an accurate extraction constant (Kext=0.02) used in the facilitated transport modeling. The flat sheet supported liquid membrane (FSSLM) experiments were conducted in the condition of 1.378 mmol/L Ge (100 mg/L), tartaric acid concertation of 2.760 mmol/L, 1 M HCl as a stripping phase and various Alamine 336 concentrations in the range of 0 to 35 %v/v. The FSSLM model was developed according to the Fick’s law, the diffusional transport, and equilibrium equations. According to the model, mass transfer and diffusion coefficients for various concentrations of the carrier were found. In addition, the calculated and experimental values had a good correlation with together showing the validity of the model. This model can be used in the further process simulation such as hollow fiber SLMs.Peer ReviewedPostprint (author's final draft

Recent advances in smart integrated membrane assisted liquid extraction technology

Novel processes based on SIMALE have been proposed as effective methods for the selective separation of different chemical species such as metal ions, organic/biologically important compounds and gas mixtures from different waste streams including nuclear waste. The industrial use of supported liquid membranes based on conventional liquids is limited by their relative instability and short lifetime. Under SIMALE techniques, the stability of the SLM is ensured by a modified SLM with pseudo emulsion based hollow fiber strip dispersion or non-dispersive solvent extraction techniques. In order to promote operational stability, SIMALE, using ionic liquids, as a liquid membrane phase could overcome these inconveniences due to their negligible vapour pressure and the possibility of minimizing their solubility in the surrounding phases. SIMALE studies on membrane-based dense gas extraction reported higher extraction efficiencies when the near critical or supercritical solvent is used. This review also discuss important applications including scale up, process intensification aspects, current status of the technology and future directions.Peer ReviewedPostprint (author's final draft

Germanium transport across supported liquid membrane with Cyanex 923: Mathematical modeling

A mathematical model was developed to monitor the facilitated transport of germanium(IV) from oxalic acid solutions through a flat sheet supported liquid membrane (FSSLM) containing four trialkylphosphine oxides (Cyanex 923). The FSSLM modeling was based on the extraction constant (Kext) calculated from the liquid-liquid extraction (LLX) modeling. The LLX model presented a reliable calculation of the extraction constant (Kex= 2.057×103 L/mol4). The FSSLM model was solved using Matlab® software according to extraction constant, Fick's law, and diffusional principles. The model predicts the overall mass transfer coefficient (Korg) to be 3.84 cm/s. Using this value, diffusion coefficients (Dm) for various Cyanex 923 concentrations of 0.126, 0.252, 0.378, 0.505, 0.631 and 0.757 mol/L are found to be 8.50×10-4, 4.30×10-4, 1.87×10-4, 5.87×10-5, 2.57×10-5, 2.09×10-5 cm2/s, respectively. The results show that the diffusion rate of the current study is approximately more than that of similar FSSLM systems containing Cyanex 923 used to transport various metals. The modeling values are in good agreement with the experimental data, showing the good reliability of the mathematical model.Peer ReviewedPostprint (author's final draft

Response surface methodology based on central composite design for simultaneous adsorption of rare earth elements using nanoporous calcium alginate/carboxymethyl chitosan microbiocomposite powder containing Ni0.2Zn0.2Fe2.6O4 magnetic nanoparticles: Batch and column studies

In this research paper, the utilization of the magnetic calcium alginate/carboxymethyl chitosan/Ni0.2Zn0.2Fe2.6O4 (CA/CMC/Ni0.2Zn0.2Fe2.6O4) was investigated for the simultaneous aqueous adsorption of Nd (III), Tb (III), and Dy (III). The magnetic products were characterized by FE-SEM, EDX, XRD, FT-IR, TGA, and VSM techniques. The saturation magnetization value for Ni0.2Zn0.2Fe2.6O4 and CA/CMC/Ni0.2Zn0.2Fe2.6O4 was found to be 45.87 and 14.14 emu/g, respectively. Using RSM, a quadratic polynomial equation was obtained to predict the adsorption efficiency of each ion. Under the conditions of pH = 5.5, adsorbent dosage of 0.1 g, initial concentration of 30 mg/L, and contact time of 53 min predicted by RSM, the adsorption efficiencies of Nd (III), Tb (III), and Dy (III) were respectively 95.72, 96.17, and 99.44%. The isotherm and kinetic data were respectively fitted well with Freundlich and pseudo-second-order (PSO) models. The desorption of the loaded ions was effectively carried out by 0.2 M HNO3, and the adsorbent was consecutively utilized with 2.54, 1.63, and 1.16% decrease in adsorption efficiency for Nd (III), Tb (III), and Dy (III), respectively, after the forth cycle. Additionally, the adsorption behavior of the CA/CMC/Ni0.2Zn0.2Fe2.6O4 towards Nd (III), Tb (III), and Dy (III) was studied by using a fixed-bed column technique.This work has been supported by the Spanish Ministry of Economy and Competitiveness (Ref. CTM2017-83581-R). Hamedreza Javadian acknowledges the financial support received (Ref. BES-2015-072506).Peer ReviewedPreprin

Sorption and desorption studies of Pb(II) and Ni(II) from aqueous solutions by a new composite based on alginate and magadiite materials

A new composite material based on alginate and magadiite/Di-(2-ethylhexyl) phosphoric acid (CAM-D2EHPA) was successfully prepared by previous impregnation of layered magadiite with D2EHPA extractant, and then immobilized into the alginate matrix. Air dried beads of CAM-D2EHPA were characterized by FTIR and SEM–EDX techniques. The sorbent was used for the separation of lead and nickel from nitrate solutions; the main parameters of sorption such as contact time, pH of the solution, and initial metal concentration were studied. The beads recovered 94% of Pb(II) and 65% of Ni(II) at pH 4 from dilute solutions containing 10 mg L-1 of metal (sorbent dosage, S.D. 1 g L-1). The equilibrium data gave a better fit using the Langmuir model, and kinetic profiles were fitted using a pseudo-second order rate equation. The maximum sorption capacities obtained (at pH 4) were 197 mg g-1 and 44 mg g-1 for lead and nickel, respectively. The regeneration of the sorbent was efficiently carried out with a dilute solution of HNO3 (0.5 M). The composite material was reused in 10 sorption–elution cycles with no significant differences on sorption uptake. A study with synthetic effluents containing an equimolar concentration of both metals indicated a better selectivity towards lead ionsPeer ReviewedPostprint (published version

Using fuzzy inference system to predict Pb (II) removal from aqueous solutions by magnetic Fe3O4/H2SO4-activated Myrtus Communis leaves carbon nanocomposite

In this research study, a magnetic nanocomposite consisting of the Fe3O4 nanoparticles immobilized on Myrtus Communis-derived activated carbon (MM-AC) was synthesized and then, characterized by FE-SEM and FT-IR analytical methods. The results showed that the sizes of the Fe3O4 nanoparticles were about 54¿nm, and the changes in the intensities of the major peaks were associated with the binding process. The adsorption efficiency of the MM-AC was evaluated for Pb (II) removal from aqueous solutions. The effective parameters such as pH, adsorbent dosage, contact time and initial metal ion concentration were optimized to reach maximum Pb (II) removal efficiency (%). The equilibrium amount of Pb (II) adsorbed onto the MM-AC suggested that the removal of Pb (II) followed Langmuir model. The kinetic studies on the removal of Pb (II) revealed that the adsorption process obeyed pseudo-second-order kinetic model. The maximum Pb (II) removal efficiency by the MM-AC was obtained at pH¿=¿5. The adsorption capacity of Pb (II) onto the MM-AC changed from 88.65 to 480.90¿mg/g by increasing the initial concentration of Pb (II) in the range of 100–400¿mg/L. The comparison of maximum monolayer adsorption capacity of the MM-AC with other adsorbents reported in the literatures for removal of Pb (II) indicated that the MM-AC had better removal efficiency. In order to predict Pb (II) removal efficiency, a methodology based on fuzzy inference system (FIS) including multiple inputs and one output was developed. Four input variables namely pH, contact time (min), adsorbent dosage (g), and initial concentration of Pb (II) were fuzzified using an artificial intelligence-based approach. A Mamdani-type of fuzzy inference system was applied to implement a total of 18 rules in IF-THEN format along with a fuzzy subset consisting of a combination of Triangular and Trapezoidal membership functions in eight levels. The max-min method was employed as fuzzy inference operator, while defuzzification process was conducted using the center of gravity (COG, centroid) method. The achieved coefficient of determination value (R2>¿0.99) confirmed the excellent accuracy of fuzzy logic model as a trustworthy prediction tool for Pb (II) removal efficiency. The overall results suggested that the developed material can be employed as an efficient adsorbent for Pb (II) removal from polluted aqueous solutions on a full-scale operation.Peer ReviewedPostprint (author's final draft

Neodymium recovery by chitosan/iron(III) hydroxide [ChiFer(III)] sorbent material: Batch and column systems

A low cost composite material was synthesized for neodymium recovery from dilute aqueous solutions. The in-situ production of the composite containing chitosan and iron(III) hydroxide (ChiFer(III)) was improved and the results were compared with raw chitosan particles. The sorbent was characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy-energy dispersive X-ray analyses (SEM-EDX). The equilibrium studies were performed using firstly a batch system, and secondly a continuous system. The sorption isotherms were fitted with the Langmuir, Freundlich, and Sips models; experimental data was better described with the Langmuir equation and the maximum sorption capacity was 13.8 mg g-1 at pH 4. The introduction of iron into the biopolymer matrix increases by four times the sorption uptake of the chitosan; the individual sorption capacity of iron (into the composite) was calculated as 30.9 mg Nd/g Fe. The experimental results of the columns were fitted adequately using the Thomas model. As an approach to Nd-Fe-B permanent magnets effluents, a synthetic dilute effluent was simulated at pH 4, in order to evaluate the selectivity of the sorbent material; the overshooting of boron in the column system confirmed the higher selectivity toward neodymium ions. The elution step was carried out using MilliQ-water with the pH set to 3.5 (dilute HCl solution).Peer ReviewedPostprint (published version

Non-dispersive selective extraction of germanium from fly ash leachates using membrane-based processes

Non-dispersive selective extraction of Ge(IV) tartrates was carried out from simulated fly ash solutions containing heavy metals through supported liquid membranes (SLM). The optimum transport was obtained using a PTFE membrane containing Alamine 336 5%v/v in the condition of tartaric acid 2.76 mmol/L and HCl 1 mol/L in feed and strip phases, respectively. Under this condition, a hollow fiber (HF) SLM experiment was conducted. The results showed that this system could transport germanium from the feed to the strip phase so much faster than the flat sheet (FS) SLM system. The rate of transport through HFSLMs is comparable to dispersive extractions.Peer ReviewedPostprint (author's final draft

Simulation of non-linear flow density in transition state from the mathematical model of the diffusion of metal anions through a flat sheet supported liquid membrane

A mathematical model is developed for the carrier facilitated transport of metal ions through a flat sheet support liquid membrane (FSSLM) in transition state from Fick’s second law. From this model, and from Fick’s first law, the flow density is derived as a non-linear concentration gradient. Both expressions, concentration and flow density, depend on the thickness of the membrane and on time. Since the rate constant plays an important role in the model, it is considered as the parameter that controls the system and an equation for it is obtained. This equation explains the velocity of the co-transport process. The proposed model takes into account the species co-transported together with the metal ions. An equation for the number of moles of this species is obtained as a function of the metal species. The concentration gradient of this species explains the behaviour of pH in the feed phase during the process. The model is tested against experimental data corresponding to the transport of metal anions in acidic solution and it is shown that the co-transport process is reproduced with high accuracy.Peer Reviewe

Transport of Zn(II), Fe(II), Fe(III) across polymer inclusion membranes (PIM) and flat sheet supported liquid membranes (SLM) containing phosphonium ionic liquids as metal ion carriers

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Separation Science and Technology on 18/04/2016, available online: http://www.tandfonline.com/doi/full/10.1080/01496395.2016.1174265In this work transport of Zn(II), Fe(II) and Fe(III) ions from chloride aqueous solutions across polymer inclusion membranes (PIMs) and supported liquid membranes (SLMs) containing one of three phosphonium ionic liquids: trihexyl(tetradecyl)phosphonium chloride (Cyphos IL 101), trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate (Cyphos IL 104) and tributyl(tetradecyl)phosphonium chloride (Cyphos IL 167) as an ion carrier was reported. The results show that Zn(II) and Fe(III) are effectively transported through PIMs and SLMs, while Fe(II) transport is not effective. The highest values of initial flux and permeability coefficient of Zn(II) were noticed for SLM containing Cyphos IL 167. Cyphos IL 101-containing SLM is more stable than PIM.Peer ReviewedPostprint (author's final draft