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Selective separation of some heavy metals by poly(vinyl alcohol)‐grafted membranes
Abstract
A poly(vinyl alcohol) membrane (PVA) was modified by radiation graft copolymerization of acrylic acid/styrene (AAc/Sty) comonomers. The Cu and Fe ion-transport properties of these membranes were investigated using a diaphragm dialysis cell. In the feed solution containing CuCl2 or a mixture of CuCl2 and FeCl3, the PVA-g-P(AAc/Sty) membranes showed high degrees of permselectivity toward Cu2+ rather than toward Fe3+. The permeation of Cu2+ ions through the membranes was found to increase with decrease in the grafting yield. However, as the content of Cu2+ ions in the Cu/Fe binary mixture feed solutions decreased, the rate and the amount of transported Cu2+ through the grafted membrane decreased, with no appreciable permselectivity toward Fe3+. When Fe2+ ions were used instead of Fe3+ ions in the feed solution containing Cu2+, the transport of both Cu2+ and Fe2+ through the membrane was observed. The rate of transport of Fe2+ was higher than that of Cu2+. In addition, it was found that the selective transport of ions was significantly influenced by the pH difference between both sides of the membranes. As the pH of the feed or the received solution decreased, both Cu2+ and Fe3+ passed through the membrane and were transported to the received solution. The role of carboxylic acid and the hydroxyl groups of the grafted membranes in the transportation process of ions is discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 125–132, 2000
... Among them, heavy metals are of serious concern because most of them are highly toxic, non biodegradable and can be easily bioconcentrated in organisms and biomagnified through food chains; thus, there is a need to search new effective methods for their removal. [3,67891011121314 The most widely used methods for removing heavy metals from wastewater are coagulation and precipitation, adsorption, ion exchange treatment and coprecipitation/adsorption. In comparison with the other processes for the treatment of polluted aqueous effluents, the sorption process possesses some advantages, such as flexibility in design and operation, producing superior effluent suitable for reuse without other pollutants. ...
... All the adsorption experiments were carried out at room temperature during 24 h by mixing the solution with the hydrogel in an orbital shaker a slow rate. Likewise, the adsorption of heavy metal was estimated by calculating the removal percentage, P r , the partition coefficient, K d , and the retention capacity, Q r , as follows: [9,37,38] P r ¼ Amount of metal ion in the polymer mg ð ÞFigure 2 shows the FTIR spectra of native starch, NS, and the oxidized starches with the lower and higher oxidation, OS-1 and OS-3, respectively. During the oxidation reaction, hydroxyl groups of glucose are initially oxidized to carbonyl groups and thereafter to carboxyl groups. ...
Superabsorbent materials based on natural products have been synthesized by free radical oxidation of corn starch using a redox system consisting of potassium permanganate and sodium bisulfite. The resulting oxidized starches were characterized by analyzing the variation of carbonyl and carboxyl contents. The swelling ability of these samples has been determined by gravimetric method in water and in saline solutions. The effect of oxidant concentration and bleaching procedure on the water absorption capacity has been studied. The ability to remove heavy metals in water solution has been tested against Cd2+, Ni2+, Pb2+ and Zn2+ ions, showing higher percentage of remotion for the unbleached oxidized starches, in particular against nickel ions. Copyright © 2014 John Wiley & Sons, Ltd.
... Proposed mechanistic pathway for synthesis of graftcopolymer.been calculated by using expression(Abd EL-Rehim, EL-Sayed, & Ali, 2000). ...
... An increase in weight of graft copolymer has been recorded. Calculation of the percent swelling (P S ) and swelling ratio (S R ) is done by the following expression (Abd EL-Rehim, Hegazy EL- Sayed, & Ali, 2000). ...
... After this the sample was weighed and in- crease in weight was recorded. The behavior was studied by fol- lowing relation (EL-Rehim, Hegazy, & Ali, 2000). ...
... An increase in weight of graft copolymer has been recorded. The percent swelling (P s ) and swelling ratio (S r ) are calculated by using expression (Abd EL-Rehim, Hegazy EL- Sayed, & Ali, 2000): Percent swelling (P s ) = Swelling ratio (S r ) × 100 ...
... An increase in weight of graft copolymer has been recorded. Calculation of the percent swelling (P s ) and swelling ratio (S r ) is done by the following expression (EL-Rehim, EL-Sayed, & Ali, 2000). ...
... An increase in weight of graft copolymer has been recorded. Calculation of the percent swelling (P S ) and swelling ratio (S R ) is done by using expression (Abd EL-Rehim, Hegazy EL- Sayed, & Ali, 2000). ...
... The swollen samples were then removed from their respective triple distilled water, quickly wiped with filter paper to remove droplets on the surface and weighed. The swelling ratio (S r ) and percent swelling (P s ) have been calculated by using following expressions (Abd EL-Rehim, Hegazy EL- Sayed, & Ali, 2000). heating to form radicals (Banerjee, Srivastava, Srivastava, & Behari, 2006) represented as R • . ...
... After swelling, tea bags were suspended to remove excessive fluid, and then the whole gel was weighed. The swelling ratio (S r ) and percent swelling (P s ) were calculated by using the following expressions (EL-Rehim, Hegazy, & Ali, 2000). ...
... An increase in weight of graft copolymer has been recorded. Calculation of the percent swelling (P S ) and swelling ratio (S R ) is done by the following expression (EL-Rehim Abd, Hegazy El- Sayed, & Ali, 2000). ...
... An increase in weight of graft copolymer has been recorded. Calculation of the percent swelling (P S ) and swelling ratio (S R ) is done by the following expression (Abd EL-Rehim, Hegazy EL- Sayed, & Ali, 2000). ...
... An increase in weight of graft copolymer has been recorded. Calculation of the percent swelling (P S ) and swelling ratio (S R ) has been made by the following expression (Hegazy El-Sayed, EL-Rehim Abd, & Ali, 2000): ...
... An increase in weight of graft copolymer has been recorded. Calculation of the percent swelling (P S ) and swelling ratio (S R ) has been made by the following expression (Abd EL-Rehim, Hegazy EL-Sayed, & Ali, 2000). ...
... The swollen samples were then removed from triple distilled water, quickly wiped with filter paper to remove droplets on the surface and weighed. The percent swelling (P s ) and swelling ratio (S r ) have been calculated by using following expressions (Abd EL-Rehim, EL- Sayed, & Ali, 2000). ...
... An increase in weight of graft copolymer has been recorded. Calculation of the percent swelling (P S ) and swelling ratio (S R ) is done by using expression (Abd EL-Rehim, Hegazy Sayed, & Ali, 2000). P S ¼ Wt: of swollen polymer À Wt: of dry polymer Wt: of dry polymer  100 S R ¼ Wt: of swollen polymer À Wt: of dry polymer Wt: of dry polymer ...
Thermal analysis N-vinyl formamide Metal ion sorption Water swelling behaviour Flocculation Resistance to biodegradability a b s t r a c t j-Carrageenan-g-N-vinyl formamide was synthesized by free radical initiation using the potassium mon-opersulphate (PMS)/malonic acid redox pair in an inert atmosphere. The effects of variation of different reactant on grafting parameters have been studied by varying the concentration. Grafting ratio, add on and conversion showed an increasing trend on increasing the concentration of N-vinyl formamide, malonic acid, j-carrageenan and the concentration of PMS from 6 Â 10 À3 to 22 Â 10 À3 mol dm À3 . The optimum temperature and time for grafting of N-vinyl formamide onto j-carrageenan was found to be 40 °C and 120 min, respectively. The metal ion sorption, swelling behaviour, flocculation and resistance to biodegradation properties have been studied. Flocculation capability of j-carrageenan and j-carra-geenan-g-N-vinyl formamide for both coking and non-coking coals has been studied for the treatment of coal mine waste water. The graft copolymer was characterized by FT-IR spectroscopy and thermogravi-metric analysis.
... An increase in weight of graft copolymer has been recorded. Calculation of the percent swelling (P S ) and swelling ratio (S R ) has been made by the following expression (Abd EL-Rehim, Hegazy EL-Sayed, & Ali, 2000). ...
Carbohydrate Polymers j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c a r b p o l a b s t r a c t An unreported graft copolymer of 2-acrylamidoglycolic acid with partially carboxymethylated guar gum has been synthesized under nitrogen atmosphere using peroxymonosulphate/thiourea redox pair at 40 • C. The effect of reaction conditions on grafting parameters i.e., grafting ratio, efficiency, conversion, add on, homopolymer and rate of grafting has been studied. Experimental results show that maximum grafting has been obtained at 0.1 g dm −3 concentration of partially carboxymethylated guar gum and 5.3 × 10 −2 mol dm −3 concentration of 2-acrylamidoglycolic acid. It has been observed that grafting ratio, add on, conversion, efficiency and rate of grafting increase up to 5.0 × 10 −3 mol dm −3 of hydrogen ion, 2.4 × 10 −3 mol dm −3 of thiourea, 10 × 10 −3 mol dm −3 of peroxymonosulphate and 40 • C of temperature. Grafted copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis. Physico-chemical properties of partially carboxymethylated guar gum-g-2-acrylamidoglycolic acid have been determined.
... An increase in weight of graft copolymer has been recorded. Calculation of the percent swelling (P S ) and swelling ratio (S R ) is done by the following expression (EL-Rehim Abd, Hegazy El-Sayed, & Ali, 2000). P S ¼ Wt: of swollen polymer À Wt: of dry polymer Wt: of dry polymer  100 S R ¼ Wt: of swollen polymer À Wt: of dry polymer Wt: of dry polymer ...
a b s t r a c t An unreported graft copolymer of N,N-dimethylacrylamide (DMA) with chitosan has been synthesized under nitrogen atmosphere using peroxymonosulphate/mandelic acid redox pair. The effect of reaction conditions on grafting parameters i.e. grafting ratio, efficiency, conversion, add on and homopolymer has been studied. Experimental results show that maximum grafting has been obtained at 1.0 g dm À3 concentration of chitosan, 30 Â 10 À2 mol dm À3 concentration of N,N-dimethylacrylamide and 7.0 Â 10 À3 mol dm À3 concentration of hydrogen ion. It has also been observed that grafting ratio, add on, conversion and efficiency increase upto 3.2 Â 10 À3 mol dm À3 of mandelic acid, 12.0 Â 10 À3 mol dm À3 of potassium peroxymonosulphate, 150 min of time and 40 °C of temperature. Grafted polymer has been characterized by FTIR spectroscopy and thermogravimetric analysis. Water swelling capacity of chitosan-g-N,N-dimethylacrylamide has been determined. It has been observed that the graft copolymer is ther-mally more stable than parent backbone.
... The swollen samples were then removed from triple distilled water, quickly wiped with filter paper to remove droplets on the surface and weighed. The percent swelling (P s ) and swelling ratio (S r ) have been calculated by using following expressions (Abd EL-Rehim, Hegazy Sayed, & Ali, 2000). The beaker was placed on flocculator dipping the stirrer blade in the suspension. ...
a b s t r a c t A graft copolymer of chitosan and N-vinyl formamide has been synthesized by free radical polymeriza-tion using bromate/cyclohexanone redox in an inert atmosphere. The grafting ratio, add on, and efficiency increase continuously with increase in concentration of N-vinyl formamide from 9 Â 10 À2 mol dm À3 to 41 Â 10 À2 mol dm À3 , bromate ion from 0.4 Â 10 À2 mol dm À3 to 2.4 Â 10 À2 mol dm À3 and chitosan from 0.6 g dm À3 to 1.4 g dm À3 . Grafting parameters decrease with increase in concentration of hydrogen ion from 2 Â 10 À3 mol dm À3 to 10 Â 10 À3 mol dm À3 . Experimental results also show that these parameters i.e. grafting ratio, add on, and efficiency increase with increase in cyclohexanone concentration from 0.4 Â 10 À2 mol dm À3 to 1.2 Â 10 À2 mol dm À3 , but beyond this cited range, these parameters decrease. Maximum grafting i.e. 189.5% has been found at 120 min and 40 °C. The swelling, metal ion sorption and flocculation capability have been studied, respectively. The flocculation capability of chitosan and chitosan-g-N-vinyl formamide in both coking and non-coking coals has been studied for the treatment of coal mine waste water. The graft copolymer has been characterized by Infra red (IR) spectroscopy and thermogravimetric analysis.
... The surface water on the swollen polyacrylic acid was removed by safely pressing between the folds of the moisten filter paper, and weights were taken. Percent swelling ( ) and swelling ratio ( ) have been calculated by using the following expressions [34]: ...
The effects of concentrations of peroxymonosulphate, mercaptosuccinic acid, hydrogen ion, acrylic acid, and carrageenan on grafting parameters were studied to find out the maximum grafting ratio. The corresponding values were found to be
1
4
.
0
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1
0
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,
3
2
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1
0
−
3
,
1
5
.
0
×
1
0
−
3
,
1
8
.
0
×
1
0
−
2
mol dm−3, and
1
.
0
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1
0
−
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g dm−3, respectively. The optimal reaction time duration and reaction temperature were found to be 120 min and 40°C, respectively. The effect of hydrogen ion variation from 5.0 up to
2
5
.
0
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1
0
−
4
mol dm−3 shows prompt changes on grafting parameter. The grafted copolymer was found more thermally stable than the ungrafted substrate. Also the grafted copolymer absorbed more water, namely hazardous metal cations. Hg2+, Pb2+, and Cd2+, showed better flocculation behavior than carrageenan.
... An increase in weight of graft copolymer has been recorded. Calculation of the percent swelling (P S ) and swelling ratio (S R ) is done by the following expression (Abd EL-Rehim, Hegazy EL-Sayed, & Ali, 2000) and results are summarized in Table 5. ...
Unreported graft copolymer of 4-vinyl pyridine (4VP) with partially carboxymethylated guar gum (Cmg) was synthesized and reaction conditions were optimised using a bromate/thiourea redox pair under an inert atmosphere at 40 °C. Studies have been done to observe the effect of reactants on grafting parameters by varying the reactant concentration. Grafting ratio, add on and conversion show a decrement on increasing the concentration of partially carboxymethylated guar gum beyond 1.0 g dm−3. The grafting parameters increase on increasing the concentration of 4-vinyl pyridine from 13 × 10−2 to 25 × 10−2 mol dm−3, BrO3- from 4 × 10−3 to 10 × 10−3 mol dm−3 and thiourea from 1.6 × 10−3 to 4.8 × 10−3 mol dm−3. Optimum temperature and time for grafting of 4-vinyl pyridine on partially carboxymethylated guar gum are found to be 40 °C and 120 min, respectively. Metal ion uptake and flocculation behaviour have been also studied and found that graft copolymer shows enhancement in these properties than substrate. Swelling behaviour of graft copolymer has been investigated. The graft copolymer is characterized by FTIR and thermal analysis.
... Chen). been used for the preparation of smart materials, such as thermoand pH-responsive materials [8,9], selective metal ion adsorbing materials [10] and proton-conducting membranes [11][12][13][14]. ...
In order to prepare a polymer electrolyte hybrid membrane with both high proton conductivity and high thermal stability, an aromatic vinyl monomer having a trimethoxysilyl group, namely p-styryltrimethoxysilane, was first grafted into poly(ethylene-co-tetrafluoroethylene) (ETFE) film by γ-ray preirradiation. The p-styryltrimethoxysilane-grafted film was then sulfonated to attach sulfonic acid groups onto the aromatic rings of the graft chains, and finally hydrolyzed and condensed to introduce silane-crosslinking between the graft chains. Thus, a crosslinked proton-conducting polymer electrolyte hybrid membrane was obtained. The preparation conditions for grafting and sulfonation, and the properties of the resulting polymer electrolyte membrane, such as ion exchange capacity, proton conductivity, water uptake, and thermal stability were investigated with respect to its application in fuel cells. It is concluded that the properties of the new p-styryltrimethoxysilane-grafted polymer electrolyte hybrid membrane are comparable to Nafion, and are superior to a styrene-grafted membrane.
... The swollen samples were then removed from buffer solutions, quickly wiped with filter paper to remove droplets on the surface and weighed. The percent swelling (Ps) was calculated using the following expression; [18]. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 ...
Carboxymethyl chitosan (CMCh) was prepared and characterized by determinating its degree of substitution and elucidating its structure by elemental analyses and FTIR. Graft copolymerization of acrylonitrile (AN) onto CMCh was carried out in aqueous solution using potassium persulfate (KPS) initiator. Evidences of grafting were obtained via FTIR spectroscopy, elemental analyses, scanning electron microscopy, X-ray diffraction and the differences in swellability profiles before and after grafting. The effects of initiator concentration, monomer concentration, reaction time and temperature on the graft copolymerization were studied by determining the grafting percentage (%G), grafting efficiency (%GE) and the amount of homopolymer formed (%H). The optimum grafting conditions were determined as follows: [KPS] = 5 × 10−2 mol/L, [M] = 3 mol/L, reaction temperature = 65°C and reaction time = 3 h. The capacity of the graft copolymers to uptake metal ions from their aqueous solutions and to capture different types of dyes were also studied. The work was extended to include the amidoximation reaction of the ‒CN groups of the grafted PAN on CMCh chains and to elucidate its effect on metal uptake, dye uptake and swellability in different pH buffer solutions. Results show that the amidoxime derivatives adsorb more metal ions than both CMCh and the graft copolymers. Also it was shown that as the % graft increases, the ability of CMCh to attract more dye molecules increases and also the amidoxime derivatives attract more dye molecules than the graft copolymers.
In the present work, graft copolymers of acrylamide onto guar gum were synthesized by free radical polymerization using potassium bromate/thiourea redox initiating system. The guar gum and guar gum-g-polyacrylamide were characterized by infrared spectroscopy and thermogravimetric analysis. It was found that the guar gum-g-polyacrylamid was thermally more stable than pure guar gum. The grafting ratio, grafting efficiency, add-on, and conversion increased with the concentration of bromate and acrylamide, whereas they decreased with increasing the concentration of guar gum. The grafting ratio and grafting efficiency showed maximum value at the concentration of thiourea and hydrogen ions of 3.2×10⁻³ mol dm⁻³ and 4.0×10⁻³ mol dm⁻³, respectively, but decreased with further increasing the thiourea and hydrogen ions concentrations. The increase in temperature from 30 to 45 °C resulted in increasing the grafting ratio while decreasing the conversion. The optimum reaction time for the graft copolymerization was found to be 2 h. Compared to the parent guar gum, the graft copolymer showed higher water swelling capacity and metal ion sorption, as well as better flocculant behaviors.
Grafting of acrylamide (AAm) onto kappa-carrageenan (KC) was carried out using microwave irradiation in the presence of ammonium persulfate (APS) as initiator. The effect of reaction variables including the concentration of APS, AAm, and KC; time duration; and microwave power was studied. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were carried out to characterize the graft copolymer. The graft copolymer possesses slightly sensitive activities to external pH and shows reversible on off switching swelling characteristics. Flocculation efficacy of the graft copolymer was studied in coal fine suspension toward potential application as a flocculent. The acute oral toxicity study of the graft copolymer was evaluated as per OECD guidelines. Mice administered the graft copolymer did not show anomalous behavior during the 14-day study. No mortality was observed during the 14 days following treatment with the graft copolymer.
The present paper deals with the synthesis of chitosan-g-methacrylic acid by free radical polymerization using potassium peroxymonosulphate/cyclohcxanone as a redox pair in an inert atmosphere. The reaction conditions have been optimized by varying the reaction variables, including the concentration of methacrylic acid from (12 × 10-2 to 36 × 10-2) mol dm-3, peroxymonosulphate (0.6 × 10-2 to 1.2 × 10-2) mol dm-3, cyclohexanone (0.8 × 10 -2 to 1.6 × 10-2) mol dm-3, sulphuric acid (2 × 10-3 to 6 × 10-3) mol dm -3, chitosan (0.6 to 1.4) g dm-3 along with time duration and temperature. It has been observed that the maximum grafting ratio has been obtained at time 120 min, temperature 35°C and at 2.2 × 10 -2 mol dm-3 concentration of peroxymonosulphate. Metal ion sorption, and flocculation properties have been studied along with swelling property of graft copolymer. It has been found that graft copolymer shows enhancement in these properties and is thermally more stable than parent polymer The graft copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis.
The graft co-polymerization of vinyl monomers onto poly(vinyl alcohol) (PVA) by ammonium vanadate (AV) was studied as a function of H2O 2/AV mole ratio, PVA/monomer weight ratio, sulfuric acid concentration, and reaction time and temperature. The presence of hydrogen peroxide at 2 N H2SO4 improves the grafting efficiency of vanadium(V). The optimum time and temperature of the grafting reaction was found to be 3.5 h and 55°C respectively for the most reactive vinyl monomer studied. FT-IR spectroscopy was used for the confirmation of grafting. The thermal stability of the grafted polymer was evaluated. A generalized reaction scheme has been suggested to elucidate the role of vanadium(V) and hydrogen peroxide.
Graft copolymer of alginate and acrylamide was synthesized by grafting acrylamide chains on to alginate by free radical polymerization using potassium bromate/ thiourea redox system in an inert atmosphere. The reaction conditions for maximum grafting have been optimized by varying the reaction variables, including the concentration of acrylamide (3.0×10(2) - 9.3×10(2) mol dm(-3)), potassium bromate (8×10(-3) - 16×10(-3) mol dm(-3)), thiourea (1.6×10(-3) - 4.8×10(-3) mol dm(-3)), sulphuric acid (3.0×10(-3) - 7×10(-3) mol dm(-3)), alginate (0.6-1.6g dm(-3)) along with time duration (60-180min) and temperature (30-50°C). Water swelling capacity, metal ion sorption, flocculation and resistance to biodegradability studies of synthesized graft copolymer have been performed with respect to the parent polymer. The grafted polymers were characterized by FTIR spectroscopy and thermo gravimetric analysis.
Recently, the intelligent nano-polymer modified nano-particles have showed much potential in advanced materials. This chapter reviews the synthesis, characterization and properties of smart core-shell nano-composites of intelligent polymers and nano-particles. The stimuli-responsive polymeric and hybrid materials have been synthesized as nano-structured particles in a range of sizes, from nanometers to a few micrometers in the form of homo- and copolymer nano-gels, core-shell structures, micelles, dendrimers, grafted surface nano-particles, nano-composites, thin films, and more complex architectures. Furthermore, the nano-materials can be synthesized by different techniques, which include physical or chemical procedures, such as precipitation and polymeric crosslinking, respectively. Ionizing radiation techniques also have been used to obtain grafted nano-materials. The chapter further explores these nano-material synthesis techniques.
Poly(HEMA) chains grafted chemically modified Holarrhena antidysenterica fiber was converted into cation-exchanger using phosphorylation and p-doping technique. The cation-exchanger synthesized was found to remove about 94.6% methylene blue dye from aqueous solution. The graft copolymer and cation exchanger vis-a-vis backbone were characterized using different techniques like FTIR, SEM, EDX and XRD. The samples were further evaluated for thermal behavior using TGA/DTA/DTG techniques. The synthesized cation-exchanger was found to possess high thermal stability.
In the presence of catalytic amount of ammonium persulfate as initiator, the grafting of polyacrylamide (PAAm) onto gellan gum (GG) was carried out using microwave irradiation. The grafting condition was optimized by varying the microwave power, exposure time, and concentrations of initiator, monomer, and GG. Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy analysis were employed to confirm that PAAm has been grafted onto the GG backbone. The intrinsic viscosity of pure and grafted samples has been measured by using Oswald viscometer. Swelling behavior of graft copolymer has been investigated and pH sensitivity of the graft copolymer was obtained. The flocculation characteristics of grafted and ungrafted polysaccharides have been evaluated in coal (coking and non-coking) suspensions. Graft copolymer shows better flocculation efficacy compared to the base polysaccharides.
In this study, xanthan gum-g-2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) was synthesized by free radical polymerization using bromate/thiourea redox pair in inert atmosphere. Various studies have been conducted to observe the effect of reactants on grafting parameters by varying the reactant concentration and to understand the physical–chemical properties. Grafting ratio, add on, and conversion showed a decrease on increasing the concentration of xanthan gum. The grafting parameters increased on increasing the concentration of AMPS from 3 × 10−2 to 6 × 10−2 mol dm−3, BrO3 from 2 × 10−3 to 8 × 10−3 mol dm−3, and thiourea from 1 × 10−3 to 2.8 × 10−3 mol dm−3, respectively. Optimum temperature and time for grafting of AMPS on xanthan gum were found to be 35°C and 120 min. Water swelling capacity, swelling ratio, metal ion uptake, and metal retention capacity were also studied, and it was found that grafted polymer shows better enhancement in these properties than substrate. Graft copolymer was characterized by FTIR and thermal analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 470–478, 2007
The present paper reports the graft copolymerization of N, N-dimethylacrylamide onto gellan gumby free radical polymerization using potassium peroxymonosulphate/sarbose redox system in an inert atmosphere. The reaction conditions for maximum grafting have been optimized by varying the reaction variables, including the concentration of N, N-dimethylacrylamide(4.0×10(-2)-20×10(-2)mol dm(-3)), potassium peroxymonosulphate (0.6×10(-2)-1.4×10(-2)mol dm(-3)), sarbose (0.4×10(-3)-3.6×10(-3)mol dm(-3)), sulphuric acid (2.0×10(-3) - 10×10(-3)mol dm(-3)), gellan gum(0.6-1.4g dm(-3)) along with time duration (60-180min) and temperature (25-45°C).Water swelling capacity, metal ion sorption and flocculation studies of synthesized graft copolymer have been performed with respect to the parent polymer. The graft copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis.
Graft copolymer of N-(hydroxymethyl) acrylamide with carboxymethylated guar gum was synthesized and the reaction conditions were optimized for better yield using potassium peroxymonosulfate and thiourea as a redox initiator. The optimum reaction conditions for grafting have also been determined by studying the effect of N-(hydroxymethyl) acrylamide, hydrogen ion, peroxymonosulphate, thiourea concentration and carboxymethylated guar gum along with time and temperature. Experimental results show that maximum grafting has been obtained at 1.4 g dm−3 concentration of carboxymethylated guar gum and 16 × 10−2 mol dm−3 concentration of N-(hydroxymethyl) acrylamide. It has been observed that grafting ratio, add on, conversion, efficiency and rate of grafting increase up to 6.0 × 10−3 mol dm−3 of hydrogen ion, 2.4 × 10−3 mol dm−3 of thiourea, 14 × 10−3 mol dm−3 of peroxymonosulphate and 35 °C of temperature. Grafted copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis. Water swelling, flocculating, and metal ion uptake properties of partially carboxymethylated guar gum-g-N-(hydroxymethyl) acrylamide have been determined.
The synthesis of graft copolymer (κ-carrageenan-g-vinylsulfonic acid) is carried out in nitrogen atmosphere using potassium peroxymonosulfate (PMS) and malonic acid (MA) as redox system. The effect of reaction variables including the concentration of vinylsulfonic acid 1.3×10(-2) to 6.7×10(-2) mol dm(-3), PMS 4×10(-3) to 20×10(-3) mol dm(-3), MA 1.6×10(-3) to 4.8×10(-3) mol dm(-3), sulfuric acid 1×10(-3) to 8×10(-3) mol dm(-3), κ-carrageenan 0.4-1.8 g dm(-3) as well as time duration 60-180 min and temperature 25-45 °C has been studied. The water swelling capacity of graft copolymer is investigated. Flocculation property for both coking and non-coking coals is studied for the treatment of coal mine waste water. The graft copolymer has been characterized by FTIR and thermogravimetric analysis.
Graft copolymer of k-carrageenan and N,N-dimethylacrylamide has been synthesized by free radical polymerization using peroxy-monosulphate/glycolic acid redox pair in an inert atmosphere. The grafting parameters i.e. grafting ratio, add on and efficiency decrease with increase in concentration of k-carrageenan from 0.6 to 1.4 g dm À3 and hydrogen ion from 3 · 10 À3 to 7 · 10 À3 mol dm À3 , but these grafting parameters increase with increase in concentration of N,N-dimethylacrylamide from 16 · 10 À2 to 32 · 10 À2 mol dm À3 , and per-oxymonosulphate from 0.8 · 10 À2 to 2.4 · 10 À2 mol dm À3 . The metal ion sorption, swelling behaviour and flocculation properties have been studied. The intrinsic viscosity of pure and grafted samples has been measured by using Ubbelohde capillary viscometer. Floccu-lation capability of k-carrageenan and k-carrageenan-g-N,N-dimethylacrylamide for both coking and non-coking coals has been studied for the treatment of coal mine waste water. The graft copolymer has been characterized by Infrared (IR) spectroscopy and thermogravi-metric analysis. Ó 2007 Published by Elsevier Ltd.
a b s t r a c t The present paper reports the graft copolymerization of N-vinylformamide onto sodium carboxymeth-ylcellulose by free radical polymerization using potassium peroxymonosulphate/thiourea redox sys-tem in an inert atmosphere. The reaction conditions for maximum grafting have been optimized by varying the reaction variables, including the concentration of N-vinylformamide (12.0 Â 10 À2 – 28.0 Â 10 À2 mol dm À3), potassium peroxymonosulphate (4.0 Â 10 À3 –12.0 Â 10 À3 mol dm À3), thiourea (1.2 Â 10 À3 –4.4 Â 10 À3 mol dm À3), sulphuric acid (2.0 Â 10 À3 –10.0 Â 10 À3 mol dm À3), sodium carboxy-methylcellulose (0.2–1.8 g dm À3) along with time duration (60–180 min) and temperature (25–45° C). Water swelling capacity, metal ion sorption and flocculation studies of synthesized graft copolymer have been performed with respect to the parent polymer. The graft copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis.
The synthesis of graft copolymer [κ-carrageenan-g-N-(hydroxymethyl) acrylamide] is carried out in nitrogen atmosphere using potassium peroxymonosulphate (PMS) and glycolic acid (GA) as redox system. The effect of reaction variables including the concentration of N-(hydroxymethyl) acrylamide (4×10(-2) to 36×10(-2))moldm(-3), PMS (4×10(-3) to 20×10(-3))mol dm(-3), GA (1.6×10(-3) to 4.8×10(-3))moldm(-3), sulphuric acid (4×10(-3) to 12×10(-3))moldm(-3), κ-carrageenan (0.6-1.8)gdm(-3) as well as time duration (60-180)min and temperature (25-45)°C has been studied. The physicochemical properties of graft copolymer synthesized have been performed in terms of water swelling, metal ion sorption and flocculation with respect to the κ-carrageenan as a parent polymer. The graft copolymer has been characterized by FTIR and thermogravimetic analysis.
Graft copolymer of partially carboxymethylated guar gum (CMGOH) and N-vinylformamide (NVF) was synthesized by free radical polymerization using 2,2-Azobis [2-(2-imadazolin-2-yl) propane] dihydrochloride (AIPH) as initiator. The effect of various reaction parameters such as concentration of NVF, CMGOH, sulphuric acid and AIPH, as well as reaction time and temperature were investigated, and the grafting conditions were optimized. Percent total conversion, % grafting, grafting efficiency (%) and percent add on under different conditions were evaluated and compared. The reaction mechanism for graft copolymerization discussed. Studies on swelling, metal ion uptake and flocculation properties were carried out in aqueous medium and the results obtained are presented and discussed. Both CMGOH and its corresponding graft copolymer samples were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. Looking at the reasonable results obtained, the synthesized graft copolymers CMGOH-g-NVF, may be exploited as potential candidates for some industrial important applications as flocculent superabsorbent, and other similar applications.
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The behavior of europium, strontium and cesium on ion exchange resins prepared from polyvinyl alcohol grafted with citric or succinic acid was investigated using gamma spectroscopy in three different media (HNO3, HCl, and H2SO4). The investigation shows that adsorption of the studied elements depends on the concentration of grafted succinic or citric acid and the concentration of the used acidic media. The time needed to reach the adsorption equilibrium is relatively short. The resins were prepared by irradiation of ternary mixtures of PVA / citric or succinic acid / water by gamma irradiation dose of 25 kGy in air and at ambient temperature. The maximum swelling and gel fraction of the prepared resins were investigated. Swelling and gelation decrease with increasing the concentration of citric acid. The decrease in the maximum swelling is due to increased hydrogen bonding between the carboxyl groups of the bonded/trapped citric or succinic molecules and the hydroxyl groups of the polymer. The decrease in the gel fraction can be explained by the presence of the acid that leads to other reactions in the mixture and not preferably to building cross links between the polymer chains.
The graft copolymerization of N,N'-dimethylacrylamide onto guar gum initiated by potassium peroxymonosulphate/glycolic acid redox pair in an aqueous medium was studied gravimetrically under a nitrogen atmosphere. Grafting ratio, grafting efficiency and add on increase on increasing the concentration of potassium peroxymonosulphate (8.0×10(-3) to 24.0×10(-3)moldm(-3)) and glycolic acid concentration (4.4×10(-3) to 7.6×10(-3)moldm(-3)). On increasing the hydrogen ion concentration from 4×10(-3) to 12.0×10(-3)moldm(-3), grafting ratio, efficiency, add on and conversion were increased. Maximum grafting was obtained when guar gum and N,N'-dimethylacrylamide concentration were 1.0×10(-2)gdm(-3) and 14.0×10(-2)moldm(-3), respectively. An increase in temperature from 25°C to 45°C, the grafting ratio increases but conversion and homopolymer decrease. The optimum time period for graft copolymerization was 2h. The graft copolymers were characterized by IR spectroscopy and thermogravimetric analysis.
A superabsorbent composite (alginate-g-PAMPS/MMT) was prepared by graft copolymerization from alginate, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and Na+ montmorillonite (MMT) in an inert atmosphere. Effects of polymerization variables on water absorbency, including the content of Na+ montmorillonite, sodium alginate, N,N′-methylenebisacrylamide and AMPS, were studied. The introduced montmorillonite formed a loose and porous surface and improved the water absorbency of the alginate-g-PAMPS/MMT superabsorbent composite. Swelling behaviors of the superabsorbent composites in various cationic salt solutions (NaCl, CaCl2 and FeCl3) and anionic salt solutions (NaCl and Na2SO4) were also systematically investigated. The superabsorbent composite was further characterized using Fourier transform infrared spectroscopy (FTIR), rheology, thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) taking alginate-g-PAMPS as a reference.
To synthesize a hydrolyzed graft copolymer, the reaction conditions have been optimized to afford maximum grafting followed by maximum absorbency by varying the concentrations of methacrylic acid (from 8×10−2 to 24×10−2moldm−3), potassium peroxymonosulphate (from 0.4×10−2 to 2.0×10−2moldm−3), silver nitrate (from 1.2×10−3 to 4.4×10−3moldm−3), hydrogen ion (from 1.0×10−3 to 9.0×10−3moldm−3) and partially carboxymethylated guar gum (from 0.4 to 1.8gdm−3) along with N,N′-methylene bisacrylamide (3.0×10−3 to 7.0×10−3moldm−3). The optimum time and temperature for grafting were found to be 40°C and 120min, respectively. The saponification reaction of graft copolymer synthesized has been carried out using NaOH (1.5–3.5N). The effect of methacrylic acid and N,N′-methylene bisacrylamide concentrations on swelling ratio for graft copolymer synthesized i.e. partially hydrolyzed graft copolymer (H-CmgOH-g-MAA) is investigated in water. The graft copolymer is characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis.
The graft reaction of succinic anhydride onto poly(vinyl alcohol) (PVA) was catalyzed by p-toluenesulfonic acid monohydrate in solid state. The infrared spectra and 1H-NMR spectra confirmed that succinic anhydride was successfully grafted onto PVA backbone. The influences of reaction temperature, reaction time, the amount of succinic anhydride, and the amount of catalyst on the graft reaction were studied. Uncrosslinked PVA graft copolymer with grafting degree up to about 6.5% could be obtained under low reaction temperature, short reaction time, and low amount of catalyst, whereas crosslinked PVA with high gel content could be obtained under high reaction temperature, long reaction time, and high amount of catalyst. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 848–852, 2007
The transport of cadmium and iron through a poly(vinyl chloride)/poly(methyl methacrylate-co-divinyl benzene) carboxylic ion-exchange membrane was investigated with a system containing HCl as the receiver solution and CdCl2 or FeCl3 as the feed solution. Transport of the ions through the membrane depended on the H+ concentration in the receiver solution and the metal concentration in the feed solution. The rate of transfer for cadmium was about 35% higher than that for iron under the same conditions (0.5 mol/dm3 of HCl, 0.1 mol/dm3 of CdCl2 or FeCl3, and 5 h of dialysis). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 705–707, 2005
An unreported graft copolymer of N‐vinyl‐2‐pyrrolidone (N‐VP) with sodium carboxymethylcellulose has been synthesized under nitrogen atmosphere using peroxymonosulphate/thiourea redox pair at 40°C. The effect of reaction conditions on grafting parameters i.e., grafting ratio, efficiency, conversion, add on, homopolymer and rate of grafting has been studied. Experimental results show that maximum grafting has been obtained at 0.4 g dm concentration of sodium carboxymethylcellulose and 10×10 mol dm concentration of N‐vinyl‐2‐pyrrolidone. It has been observed that grafting ratio, add on, conversion, efficiency and rate of grafting increase up to 6.0×10 mol dm of hydrogen ion, 2.84×10 mol dm of thiourea, 5.0×10 mol dm of peroxymonosulphate and 45°C of temperature after that decrease. Grafted and ungrafted gum has been characterized by FTIR spectroscopy and thermogravimetric analysis. Water swelling and metal ion sorption behavior of sodium carboxymethylcellulose and sodium carboxymethycellulose‐g‐N‐vinyl‐2‐pyrrolidone have been determined. A probable mechanism has been suggested for graft copolymerization. It has been observed that the graft copolymer is thermally more stable than the parent polymer.
Polyacrylonitrile was grafted to Ipomoea hederacea (Ih) seed gum with 138.5% grafting yield and 43.55% grafting efficiency in a procedure that was performed under homogeneous microwave (MW) irradiation conditions for 70s in the absence of a radical initiator. Under similar conditions, a maximum grafting yield of 108% and 33.96% efficiency was achieved when the K2S2O8/ascorbic acid redox system was used as a radical initiator in a thermostatic water bath at 35°C. The effects of reaction variables, such as monomer/Ih seed gum concentration, MW power, and exposure time on the graft copolymerization were studied. The partially hydrolyzed graft copolymer (H-Ih-g-PAN) formed a loose, porous surface and improved the water absorbency of Ih seed gum. The swelling behavior of H-Ih-g-PAN in various ionic salt (NaCl, MgCl2 and Na2SO4) solutions was also systematically investigated. The graft copolymer was further characterized using FTIR, TGA, XRD, and SEM.
The sorption and transport of metal ions by poly(vinyl alcohol) hydrogel membranes (PVA HG), obtained by physical crosslinking through the freezing/thawing method, was analyzed using aqueous nitrate solutions of copper, lead, and nickel, at concentrations ranging from 1 to 100 mM, at 25 degrees C. The sorption of heavy metal by PVA HG has been characterized by swelling and loading degrees. The effect of the heavy metals incorporation on the chemical properties of PVA HG matrices has been studied using SEM, to observe changes in the surface morphology of PVA HG membranes, and FTIR-ATR, aiming to monitor the heavy metals ions sorption into PVA hydrogel membranes. The analysis of permeation and diffusion coefficients of 100 mM aqueous solutions of Cu(2+), Ni(2+), and Pb(2+) show that the diffusion process may be mainly described by hydrodynamic models; however, the transport process shows that the distribution coefficient for the different heavy metals are always higher than one, in agreement, with the sorption studies. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 1567-1573, 2010
A series of crosslinked cation-exchange membranes having graded levels of ion-exchange capacity were prepared by irradiation-induced grafting on polyethylene substrates. A kinetic model was proposed for the transport of metal counterions across the membrane in Donnan dialysis. The transport was found to be adequately described by an equation in which the rate is proportional to the metal concentration. Sulfonated styrene-grafted membranes were more effective than acrylic acid-grafted membranes in Donnan dialysis separation applications. The metal transport rate increased with increasing ion-exchange capacity of the membrane. The metal removal rates were essentially the same with sodium sulfate, sodium chloride, or sulfuric acid as the strip agent; however, the use of chelating trisodium ethylenediaminetetraacetate brought about higher rates of metal removal. The rate of metal transport across a membrane of low ion-exchange capacity and gel water content decreased with increasing size and valence of the metal cation. However, negligible effect was observed concerning the size and valence of a metal cation on the metal's transport across a membrane of high ion-exchange capacity and gel water content.
The complexation of amino functions supported on polyacrylamides with 2–20 mol% of divinylbenzene (DVB) crosslinks was investigated towards Co(II), Ni(II), Cu(II), Zn(II) and Hg(II) ions. With increasing extent of DVB-crosslinking, the metal ion intake decreased in the order: Hg(II) >> Cu(II) > Zn(II) > Ni(II) > Co(II). The polymeric ligand and the derived metal complexes were characterized by their typical i.r. absorptions and from the e.s.r. spectra. The i.r. absorptions of the polymeric ligands were shifted by complexation. The e.s.r. parameters suggested the distorted tetragonal geometry of the Cu(II) complexes. The change in surface morphology on complexation was followed by scanning electron microscopy. The thermal stability varied with the incorporation of metal ions. The activation energy values and the extent of crosslinking in Cu(II) complexes fit into the general equation for a cubic polynomial. The time-course and kinetics of complexation and the adsorption characteristics of complexation were also followed. The swelling characteristics varied with the extent of crosslinking, and the extent of swelling was lower for the complexed resins. The complexed resins can be recycled several times, and the Cu(II)-desorbed resin showed specificity to the Cu(II) ion in the presence of other metal ions.
Donnan dialysis concentration of cupric ions was examined experimentally, using four commercial membranes and synthetic membranes prepared by the paste method. The enrichment rate and its ratio in Donnan dialysis were affected by membrane properties. From experimental results using commercial membranes, a large value of (ion-exchange capacity)(self-diffusion coefficient of cupric ion)/(membrane thickness) was found to be a criterion of high ionic flux through a membrane. Diffusion coefficient, ion-exchange capacity and water content of a synthetic membrane were affected mainly by the degree of crosslinking of the membrane. A synthetic membrane with a degree of crosslinking of 0.02 and reinforced by polyvinyl chloride cloth showed higher ionic flux and lower flux of osmotic water, and gave a higher enrichment ratio than those of the commercial membranes used in this work.
A membrane made of the lactone-containing polymer poly(3-vinyl-1,4-butyrolactone-co-acrylonitrile) exhibited active transport and selective transport of alkali metal ions. The active transport of metal ions was promoted by H+. In the selective transport, the selectivity depended on both the affinity of the carrier fixed to the membrane for alkali metal ions and the hydrophobicity or hydrophilicity of the membrane.
Cu(II) and Ag(I) or Ni(II) are selectively removed from acidic aqueous transition metal ion mixtures by polymers containing chelating ligands based on derivatives of N,N′-bis(2-pyridylmethyl)-2,2′-diaminobiphenyl (1) and N-(2-pyridylmethyl)-2,2′-diaminobiphenyl (6). Chelated ions are recovered by stripping with 6 N mineral acid. Polymer chelating capacities depend on the ligand structure but range up to 1.7 mmol of metal ion per gram of polymer, corresponding to over 90% utilization of chelating sites.
Investigations were carried out on different ionic membranes, which were prepared by radiation-induced graft copolymerization. Cationic (low density polyethylene (LPDE)-g-poly(acrylic acid) (PAAc)) and cationic/anionic (LDPE-g-P(AAc/4-vinyl pyridine (4VP)) membranes) were used to elucidate the possibility of their practical use. The metal uptake via their functional groups was determined by using atomic absorption and X-ray fluorescence. The amount of metal uptake by the prepared membranes increased significantly as the pH of the metal feed solution increased (pH ≤ 5·3) and the chelated metal ions were easily desorbed by treating the membrane with 0·1 M HCl for 2h at room temperature. The maximum uptake for a given metal was higher for the cationic/anionic membranes than for the cationic ones. The selectivity of the cationic/anionic membranes towards different metals was investigated using mixtures of two or three metals in the same feed solution. The membranes showed high selectivity towards Fe(III) ions. Characterization of the graft copolymers containing metals was determined by thermogravimetric analysis (TGA) and X-ray diffraction (XRD). TGA results showed that the decomposition of the graft copolymer in the presence of chelated metal ion occurred at temperatures above 300°C. The XRD of LDPE-g-P(AAc/4VP) treated with Fe(III) at various concentrations showed that the crystallinity decreased to a certain limiting value. The complexed copolymers could be recycled several times and showed high selectivity to the Fe(III) ion in the presence of the other metal ions investigated. This may make such grafted membranes acceptable for practical use in waste water treatment. © 1997 SCI
Interpolymer carboxylic membranes were prepared by the paste method. Transport of copper through the membrane was investigated by using a system containing HCl (receiver solution) and CuCl2 (feed solution). The transfer rate was found to be greatly affected by the membrane composition and HCl concentration in the receiver solution. A membrane based on poly(vinyl chloride)/poly(methyl methacrylate-co-divinylbenzene) with 5 wt % divinylbenzene showed the highest transfer rate. © 1995 John Wiley & Sons, Inc.
A study was made to modify water-soluble poly(vinyl alcohol) (PVA) by grafting acrylic acid and styrene (AAc/Sty) comonomers using gamma rays as an initiator. The factors that affect the preparation process and grafting yield were studied and more economical grafts under the most favorable reaction conditions were obtained. It was found that the high degree of grafting in such systems was obtained in the presence of an ethanol–water mixture in which water plays a significant role in enhancing the graft copolymerization. The critical amount of water to afford the maximum grafting yield was evaluated. The effect of the comonomer composition on the grafting yield was also investigated and it was observed that using a mixture of AAc/Sty monomers influences the extent of grafting of each monomer onto the PVA substrate and the phenomenon of synergism occurs during such a reaction. Also, the degree of grafting increases as the content of the solvent decreases in the reaction medium. However, the grafting yield increased as the total dose increased. The graft copolymer was characterized by IR and UV spectroscopic methods. The permeation of heavy metals such as Ni and Co through the grafted membranes was investigated and the efficiency of the separation process was also determined. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 806–815, 1999
When a cation exchange membrane having carboxyl groups, made of poly(isobutylene-alternative co-maleic anhydride) and poly(vinyl alcohol), was set in a diaphragm type cell, in which one side of the solution was adjusted to be acidic and the other side alkaline, metal ions were actively transported from the alkaline side to the acidic side across the membrane against the concentration gradient of metal ions between both sides. The driving force of the transport of metal ions was the difference in H+ ion concentration between both sides. It was presumed that the active transport was carried out chemically and physically. In the selective transport of metal ions, the selectivity was dependent on both the hydrated ionic radius for the metal ions and the affinity between the carrier fixed to the membrane, the carboxyl group, and the metal ions.
Anion exchange membranes containing amino groups, insoluble in acidic and alkaline aqueous solutions, were prepared from chitosan, poly(vinyl alcohol), and glutaraldehyde. Using the membrane in a diaphragm cell, one side being adjusted to be acidic and the other alkaline, it was possible to transport actively halogen ions through the membrane from the acidic side to the alkaline side against the concentration gradient between both sides of the membrane. The active transport of halogen ions through the membrane was significantly influenced by the pH difference and electric potential difference between both sides of the membrane.
Extraction processes aided by ion-exchange membranes are reported. Extraction of metal cations was carried out with a cation-exchange membrane separating the feed from the extractant. It is shown that the components of the extraction medium are very well retained in the organic phase. Stripping was carried out either through a second, identical, membrane, or by direct re-extraction. In the extraction of copper by LIX the ion transport is sensitive to the rate of stirring in the organic extractant phase. In a flow cell the copper transport is 5.6 × 10−9 mol/cm2-sec from a mixture of copper and nickel salt, 4.5 mM each. No nickel transfer was observed. Silver was selectively extracted by di(2-ethyl-hexyl)dithiophosphoric acid from a solution containing an excess of sodium thiosulfate. Extraction of acid with a long chain amine was carried out with an anion-exchange membrane separating the feed and the extractant and a second anion-exchange membrane separating the extractant and receiving solution in a three compartment cell. The aqueous solutions were not contaminated by the amine. Flux of acid was 4.7 × 10−9 mol/cm2-sec from an 0.57 M solution of sulfuric acid.
Selective transport of Ga3+ and Cu2+ was performed with a polytetrafluoroethylene membrane impregnated with long-chain alkylated cupferron (ammonium salt of N-(alkylphenyl)-N-nitrosohydroxylamine). Ga3+ is selectively concentrated from Ga3+/Al3+ binary solutions and Cu2+ from Cu2+/Zn2+ binary solutions with counter flow of H+ in both cases.