Romuald Wódzki

Recovery and Concentration of Metal Ions. II Multimembrane Hybrid System

Abstract The multimembrane hybrid system (MHS) has been developed and used for the transportation and separation of divalent metal ions from multicomponent solutions. The system consists of three membranes in series ion-exchange membrane | liquid membrane | ion-exchange membrane The experiments were performed with liquid membranes composed of di(2-ethylhexyl)phosphoric acid in kerosene and Nafion-120 perfluorosulfonic acid polymer membranes. The fluxes and separation characteristics have been determined for MHS separating a solution of Zn(II), Mn(II), Cu(II), and Ni(II) sulfates as the feed phase, and the strip phase containing sulfuric acid. The results of competitive permeation experiments have shown the selectivity order Zn(II) > Mn(II) > Cu(II) ≫ Co(II), Ni(II). High separation coefficients were found for Zn(II), Cu(II), and Mn(II) compared to Ni(II) and Co(II).

Recovery and Concentration of Metal Ions. IV. Uphill Transport of Zn(II) in a Multimembrane Hybrid System

A study has been made on the uphill transport of zinc cations across a multimembrane hybrid system (MHS) composed of two ion-exchange membranes (IEM) separated by a bulk liquid membrane (BLM). The fluxes of the Zn(II)/H countertransport were investigated as dependent on the composition and structure of ion-exchange polymer membranes (i), the solvent of a liquid membrane (ii), the feed and strip membrane area ratio (iii), and the pH of the feed solution (iv). The IEMs of various ionogenic groups (sulfonic acid, carboxylic acid, quaternized amine) and of various structure (clustered, gelatinous, porous) were examined in the MHS containing the BLM with di(2-ethylhexyl)phosphoric acid as a carrier of Zn(II) cations. It has been found that the Zn(II) fluxes are dependent on the properties of both the BLM and polymer membranes, i.e., on the BLM solvent viscosity (i), the nature and concentration of the IEM ion-exchange sites (ii), and the IEM thickness (iii). The best results were obtained when using hexane as ...

Propionic and acetic acid pertraction through a multimembrane hybrid system containing TOPO or TBP

Abstract Liquid membrane transport (pertraction) of propionic (PA) and/or acetic (AA) acid has been studied in a multimembrane hybrid system (MHS): feed‖AEM|BLM|AEM‖stripping solution. The MHS was made up of strongly basic anion-exchange membrane (AEM) and a bulk liquid membrane (BLM) composed of hexane and tri-n-octylphosphinic oxide (TOPO) or tri-n-butylphosphate (TBP). Transport rates, and carrier-dependent facilitation factors (F) were determined as dependent on the feed and carrier concentration. It was found that TBP facilitates the pertraction of AA (F≈8) and does not influence the pertraction of PA, which predominantly permeates the BLM according to the solution-diffusion mechanism. In the case of TOPO, the negative effect of transport freezing characterized by F JPAhexane>JPATBP>JAATOPO>JAAhexane>JPATOPO. The facilitation factors change typically in the sequence: (AA-TBP, F>1)>(AA-TOPO, F>1)>(PA-TBP, F≤1)>(PA-TOPO, F

Integrated hybrid membrane systems—membrane extraction and pertraction coupled to a pervaporation process

Abstract The processes of membrane extraction (ME), and pertraction of metal cations with simultaneous pervaporation (PV) of water from an organic phase, were examined and compared. The continuous membrane extraction (CME) system comprised two contactors containing the cation exchange membranes (CEMs) and a liquid organic phase circulating between them. The pertraction process was performed in a system composed of two CEMs separating the flowing liquid membrane (FLM) from the external aqueous solutions. The organic phase of CME or FLM was additionally circulated through a PV module with a hydrophilic polymer membrane. The CME–PV and FLM–PV systems were tested with the use of Zn2+ extractants such as di-(2-ethylhexyl)phosphoric acid (D2EHPA) and bis(2,4,4-trimethylpenthyl) thiophosphinic acid (Cyanex 302). According to the experimental findings, coupling the ME or pertraction to the PV process allows the continuous and efficient removal of water from the organic liquid membrane phase. The studied systems were found to work steadily with maintaining their integrity and high selectivity.

Recovery and Concentration of Metal Ions. I. Donnan Dialysis

Abstract Transport of sulfates of divalent metals [M = Mn(II), Cu(II), Co(II), Ni(II)] in a system made up of multicomponent solution of MSO4 ∣ Nafion membrane∣sulfuric acid solution was studied. It was found that Donnan dialysis results in a recovery factor amounting to 80–90% with the concentration ratio CM. strip/CM, feed not less than 30. The results of M(II)/H countertransport were compared with the results of simple dialysis of single and multiionic solutions. The technique of Donnan dialysis is efficient in preconcentrating ions for further separation in a multimembrane hybrid system employing a specific carrier of ions.

Recovery and Concentration of Metal Ions. III. Concentration and Temperature Effects in Multi membrane Hybrid System

Abstract The performance of the multi membrane hybrid system (MHS) made up of ion-exchange membranes and a bulk liquid membrane (D2EHPA in kerosene) has been examined. Fluxes and the separation between Zn(II), Mn(II), Cu(II), Co(II), and Ni(II) sulfates have been studied as dependent on the concentration of aqueous phases and temperature. The results show a saturation of fluxes at increased concentrations of aqueous feed or strip solutions. The total limiting fluxes are ∼1 × 10−9 mol/cm2.s whereas the limiting fluxes for specific metal ions vary in the range from 6 × 10−12 to 5 × 10−10 mol/cm2-s. The effect of temperature on MHS transport results in an activation energy of 16 to 30 kJ/mol depending on the metal species. The optimum conditions for separating metals are determined by the concentration of a feed solution in the range from 0.001 to 0.01 M and the concentration of sulfuric acid in a stripping solution in the range from 0.01 to 0.5 M. Selectivity coefficients βZn+Mn+Cu Co+Ni calculated as the r...

Separation of propionic and acetic acid by pertraction in a multimembrane hybrid system

Abstract Studies have been made on transport rates and separation of propionic over acetic acid by the solution-diffusion type pertraction in a multimembrane hybrid system (MHS). The membrane system has been composed of two hydrophilic, strongly basic or acidic, polymer membranes separated by a hydrophobic bulk liquid membrane. Separation of propionic and acetic acids from their aqueous solutions (0.1–0.8 M) or real fermentation broth has been studied. Experimentally observed mass transfer coefficients ( k ) range from 3.5×10 −6 to 1.5×10 −5 cm/s with the higher values for propionic acid. In the case of fermented broth the fluxes were found to depend on its pH and the pretreatment of the feed. The selectivity SEL AA PA evaluated as the ratio of propionic and acetic acid fluxes can attain values ranging from 3.5 to 5.5. The overall transport mechanism is consistent with a solution-diffusion mechanism typical for liquid membranes operating without a carrier. The fluxes and selectivity of the membrane system in respect to acetic and propionic acid have been found to depend on the viscosity of liquid membrane phase and solubility parameters characterizing both acids and solvents. A model based on fundamental physicochemical properties of the permeants and solvents (diffusion coefficients, solubility parameters and molar volumes) has been elaborated, and experimentally verified.

Membrane transport of organics. II. Permeation of some carboxylic acids through strongly basic polymer membrane

The permeability characteristics of the strongly basic polymer membrane Neosepta® AFN-7, (Tokuyama Soda) have been studied for acetic, propionic, lactic, tartaric, oxalic, and citric acid. The results were interpreted by using the model of transport in reactive membranes. The specific constants, that is, the maximum flux J max , the reactivity constant K, and the permeability coefficient (P), were calculated using the experimental quasi-stationary fluxes and the equation derived as a sum of reaction-diffusion (Michaelis-Menten-type), and the solution-diffusion transport equation. The constants K and J max were found to range from 0.1 to 5 dm 3 mol 1 and from 0.4 × 10 7 to 2.5 × 10 -7 mol cm -2 s 1 depending, on the acid properties. The values of K and J max were correlated with the dissociation constants K dis.acid , and the diffusion coefficients D aq.acid in aqueous media, respectively. It was found that the reaction- diffusion flux is predominating for all acids, except for the lactic one, when the feed concentration is lower than 0.5 mol dm -3 .

Mobile Macromolecular Carriers of Ionic Substances, 2. Transport Rates and Separation of Some Divalent Cations by Poly(oxyethylene) Phosphates

The permeation of Cu(II), Zn(II), Mn(II), Co(II), Ni(II) as facilitated by soluble macromolecular carriers (macroionophores) was investigated in a multimembrane hybrid system (MHS). The system was composed of two cation-exchange polymer membranes and an agitated bulk liquid membrane containing one of the following polymers as the transport activating component: ω-methoxy-poly(oxyethylene) phosphate (MPOEP, 1), α,ω-poly(oxyethylene) bisphosphate (POEBP, 2), and α,ω-poly(oxyethylene) bis(dimethyl phosphate) (POEBMP, 3) of various molecular mass. For comparative studies, poly(ethylene glycol)s (PEG, 4) of equivalent molecular mass (1500-6000), were also studied. The results have been analysed by comparing the overall metal cation fluxes, facilitation factors, and separation coefficients. It was found that compound 2 exhibits favourable carrier properties represented by the ionic fluxes as high as 2-10 -11 mol/(cm 2 .s). This macromolecular carrier allows the achievement of trasnport facilitation factors ranging from 10 to 100 with respect to the system without anly carrier, and from 6 to 34 with respect to the system containing an equivalent amount of PEG. The specific values depend on molecular mass of POE in 2, with a maximum at POE 2000. THe mechanism of transport when mediated by the ionic macromolecular carriers 1 and 2 is probably influenced by their bifunctional character involving the cooperation between ion exchange processes and ion binding by pseudocyclic structures of poly(oxyethylene) moieties.

Unsteady state pertraction and separation of cations in a liquid membrane system: Simple network and numerical model of competitive M2+/H+ counter-transport

The network pseudo-thermodynamic analysis has been applied for describing competitive pertraction of divalent cations with antiported univalent (hydrogen) cations. A mathematical model to be solved numerically has been developed and used to predict the separation effects caused by nonstationary conditions for a liquid membrane transport. Numerical calculations were made in order to compute such pertraction characteristics as: input and output membrane selectivity (ratio of respective fluxes), concentration profiles for cations bound by a carrier in a liquid membrane phase, and the overall separation factors. These quantities are discussed as dependent on time, the kinetic constants of interfacial reversible reactions, and diffusion coefficients of carrier species in a liquid membrane phase. The computations of fluxes and separation factors as dependent on time have revealed high separation efficiency of unsteady state pertraction as compared with steady or near-steady state process (with reactions near equilibrium state). According to the results of this study, the method of bond-graph network can be proposed as sufficient for modeling the processes of industrial interest and various fundamental phenomena underlying the effectiveness of synthetic and natural membranes.