Ion-exchange Fibers Research Articles

Carbon dioxide sequestration through novel use of ion exchange fibers (IX-fibers)

Electrical power generation and metal removal processes are practiced globally and share two common attributes that make them ideal candidates to be incorporated in a novel carbon dioxide sequestration scheme using ion exchange fibers (IX-fibers). First, the softening of boiler feed water used in power generation and the removal of metals from finishing wastewaters often employs the use of ion exchange for the purpose of selective separation. Second, both processes represent significant point source CO 2 emissions. This investigation demonstrated that using IX-fibers it is possible to sequester a portion of the CO 2 produced in these practices as carbonate alkalinity during the regeneration step of both the water softening and the trace heavy metal removal processes. Weak acid IX-fibers were used for hardness removal while hybrid cation exchange fibers (HCIX-F) loaded with hydrated Zr(IV) oxide (HZO) were used to remove toxic heavy metals such as zinc, cadmium and copper. IX-fibers offer the unique capability to use and consume CO 2 during the efficient regeneration of IX-fibers, whereas commercial ion exchange resins are not amenable to regeneration with CO 2. A much shorter intraparticle diffusion path length in cylindrical IX-fibers as compared to resin beads is the underlying reason for a highly efficient regeneration of the fibers. In addition to sequestering carbon dioxide, no hazardous or aggressive chemicals/brine solutions are present in the regenerant wastes as compared with traditional ion exchange processes.

Preparation of submicron ion-exchange fibers and application in copper ions removal from aqueous solutions

AbstractThe submicron ion-exchange fibers (IEF) of polystyrene (PS) and styrene-isoprene-styrene block copolymer (SIS) blends (80/20, w/w) obtained by electrospinning technology were further sulfonated with sulfuric acid to produce strong acidic cation ion exchange fibers. Scanning electron microscopy (SEM) images showed that there were obvious increase in the diameters, scratches, cracks, and micro-pores on the rough IEF surface. Fourier transform infrared (FTIR) spectroscopy analysis showed there were many sulfonated acid groups introduced onto the benzene wreath of styrene. The maximum adsorption capacity and the adsorption rate of copper ions were carried out and their removal rate determined by spectrophotometry. The results of the adsorption for copper ions showed that submicron IEF from PS/SIS blends with a high porosity (85%) and a high specific surface (760 m2/g) possess a rapid adsorption rate and a high ion adsorption amount (305.9 mmg/g). This high adsorption capacity suggests that the IEF can be efficiently applied to filter out toxic metal ions, and has excellent efficiency to remove copper ions from aqueous solution.

Anion Ion Exchange Fiber Based on Polyacrylonitrile (PAN) Matrixes and Its Selective Adsorption for Heavy Metal Ions

The purpose of this paper was to evaluate the capacity of anion ion exchange fiber to uptake the heavy metal(Co2+、Cu2+、Zn2+、Cd2+、Pb2+、Ag+) from the water. A new polyamine-type ion exchange fiber(IEF) based on polyacrylonitrile (PAN) with higher exchange capacities was prepared by crosslinking through hydrazine hydrate, followed reacting with diethylene triamine. FT-IR analysis indicated that amine, imido, acylamino and carboxyl groups were introduced into PAN fiber through the surface modified reaction of cross linking and amination. The structures of the IEF were characterized by means of SEM. The results showed that the surface of fiber became rougher and thicker and more heterogeneous. The static and dynamic adsorption experiments demonstrated the high selective adsorption property of the IEF for Ag+ and Cu2+. Furthermore, the adsorption mechanism for the metal ions with IEF was investigated with the FT-IR spectra studies.

Catalytic removal of hydrogen sulfide from air using Fiban ion-exchange fibers

The use of Fe(III)-EDTA complexes as catalytically active components was shown to be a promising technique in the construction of contact gas purifiers for the removal of hydrogen sulfide from gas-air mixtures. Nonwoven fabrics obtained on the basis of Fiban ion-exchange fibers and an Fe(III)-EDTA complex have good barrier properties with respect to the hydrogen sulfide of the air. The possibility of strengthening the fabrics by combining them with reinforcing materials has been demonstrated.

Hydrogen chloride absorption from the air with the fibrous ion exchangers FIBAN

Hydrogen chloride sorption from the air in a wide range of relative humidity and the concentration of the absorbing component was examined under dynamic conditions with fibrous anion exchanger FIBAN distinguishing by basicity and type of functional groups.

Is there a future for biomonitoring of elemental air pollution? A review focused on a larger-scaled health-related (epidemiological) context.

The present paper focuses on biomonitoring of elemental atmospheric pollution, which is reviewed in terms of larger-scaled biomonitoring surveys in an epidemiological context. Based on the literature information, today’s availability of solar-powered small air filter samplers and fibrous ion exchange materials is regarded as adequate or an even better alternative for biomonitor transplant materials used in small-scaled set-ups, but biomonitors remain valuable in larger-scaled set-ups and in unforeseen releases and accidental situations. In the latter case, in-situ biomonitoring is seen as the only option for a retrospective study: biomoniors are there before one even knows that they are needed. For biomonitoring, nuclear analytical techniques are discussed as key techniques, especially because of the necessary multi-element assessments in both source recognition and single-element interpretation. To live up to the demands in an epidemiological context, larger-scaled in-situ biomonitoring asks for large numbers of samples, and consequently, for large total sample masses, this all to ensure representation of both local situations and survey area characteristics. Possibly, this point should direct studies into new “easy-to-sample” biomonitor organisms, of which high masses and numbers may be obtained in field work, rather than continue with biomonitors such as lichens. This also means that both sample handling and processing are of key importance in these studies. To avoid problems in comparability of analytical general procedures in milling, homogenization and digestion of samples of large masses, the paper proposes to involve only few but high-quality laboratories in the total element assessment routines. In this respect, facilities that can handle large sample masses in the assessment of element concentrations are to be preferred. This all highlights the involvement of large-sample-volume nuclear facilities, which, however, should be upgraded and automated in their operation to ensure the necessary sample throughput in larger-scaled biomonitoring.

Adsorption and determination of bismuth with 4-(2-pyridylazo)resorcinol on a fibrous ion exchanger

The adsorption of bismuth was studied on a fibrous material filled with a Chelex 100 ion exchanger with iminodiacetic groups and a KU-2 cation exchanger, and as thiosulfate and iodide complexes on a fibrous AV-17 (PANV-AV-17) anion exchanger. Bismuth adsorbed on the solid phase was determined with 4-(2-pyridylazo)resorcinol (PAR). The optimal conditions for adsorption and determination were selected and selectivity was studied. The system bismuth-iodide-PANV-AV-17-PAR was proposed for the determination of bismuth in the solid phase. A procedure was developed for the adsorption-spectroscopic determination of 0.04–0.4 mg/L of bismuth in fresh water and urine with a detection limit of 0.03 mg/L and RSD < 20%.

Synthesis and characterization of lead(II) selective sodium dodecyl benzene sulphonate–cerium(IV) phosphate ion exchanger

The surfactant based sodium dodecyl benzene sulphonate–cerium(IV) phosphate (SDBS–CeP) fibrous ion exchanger has been synthesized and was characterized by using various physico-chemical methods. The X-ray, TGA/DTA, SEM and elemental analysis were used to characterize the ion exchanger. The ion exchange property was studied by carrying out the ion exchange capacity, elution, concentration and thermal behavior. Adsorption studies on the synthesized material have also been performed for heavy metal ions in alkalis and acidic media. The material has been found to be selective for Pb 2+and therefore, the binary separations of Pb 2+ from other metal ions have been performed on its column and observed to be quite effective in the presence of alkali, alkaline earth and transition metals.

Preparation and characterization of PVC/PS composite cation exchange fibers and their adsorption properties on aniline

AbstractBased on the composite fibers made from polyvinylchloride (PVC) and polystyrene (PS), the composite fibers obtained were further crosslinked and sulphonated with 50% oleum to produce the acidic cation ion exchange fibers. The optimal technology of the fibers obtained were discussed, the structures of the fibers thus obtained were investigated by using Fourier transform infrared (FTIR) spectrophotometry, thermogravimetry analysis (TG), differential thermogravimetry analysis (DTG), and scaning electron microscope (SEM) etc. Their properties were measured using chemical titration, filament mightiness instrument, etc. The absorption kinetics and the main factors affecting absorption capacity on aniline were studied, and their regenerating properties were probed. The results indicated that the cation exchange fibers with better mechanical property and higher exchange capability were obtained. The fibers had bigger hydrophilicity, better ability of acid, and alkali corrosion resistance, so they had better practical application value. This type of ion exchange fibers had faster absorption property and better working stability to aniline and could be used repeatedly, so they were applied for treatment of waste water containing aniline with a promising prospect. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The hydration characteristics of chemisorption fiber VION KN-1 in the nickel and zinc forms

The state of water in the zinc and nickel forms of VION KN-1 ion exchange fiber was estimated by the derivatographic and isopiestic methods. The presence of water with different degrees of binding was observed. Fiber hydration numbers corresponding to each step of water removal were determined. The Gibbs energies of fiber hydration in the Ni2+ and Zn2+ forms were calculated.

Hybrid Anion Exchange Fibers with Dual Binding Sites: Simultaneous and Reversible Sorption of Perchlorate and Arsenate

When multiple trace contaminants of significantly different chemical properties are present in a single source of contaminated water, designing an engineered sorbent for their simultaneous removal poses a major challenge. Physical–chemical properties of the sorption sites need to be tailored and expanded for preferential binding of more than one contaminant in such cases. The scientific challenge becomes increasingly complex when the sorbent requires to be reusable through intermittent regenerations. In this study, hydrated Fe(III) oxide or HFO nanoparticles were dispersed within an ion exchange fiber containing covalently attached quaternary ammonium functional groups. The resulting hybrid anion exchange fiber (HAIX-F) showed very high sorption affinity for both perchlorate and arsenate in the presence of orders of magnitude greater concentrations of competing sulfate and chloride anions. A series of experimental studies validated that relatively hydrophobic perchlorate was selectively bound to quaternary ammonium functional groups while arsenate uptake took place onto HFO surfaces through ligand exchange. The most significant finding of the study was that perchlorate and arsenate could be desorbed efficiently but separately from each other in a simple-to-operate two-step regeneration using conventional regenerants, namely, sodium hydroxide and sodium chloride solutions. In contrast, spherical anion exchange resins are not amenable to such high regeneration efficiency for perchlorate due to significantly longer diffusion path lengths. The unique sorption and desorption behaviors of HAIX-F can be easily extended to other applications where hydrophobic or polyvalent anions [e.g., pentachlorophenate, uranium(VI) oxyanion, benzenesulfonate] are simultaneously present with environmentally significant ligands, such as phosphate, oxalate, vanadate.

Removal of lead (II) from aqueous environment by a fibrous ion exchanger: Polycinnamamide thorium (IV) phosphate

The objective of the present research was to synthesize, characterize and to investigate the removal efficiency of lead (II) ion from synthetic lead solution by a hybrid fibrous ion exchanger. In the present study polycinnamamide thorium (IV) phosphate was synthesized by co-precipitation method and was characterized using SEM, XRD, FTIR and TGA–DSC. To know the practical applicability, a detailed removal study of lead ion was carried out using the material. The removal of lead was 81.2% under optimum conditions. Adsorption kinetic study revealed that the adsorption process followed first order kinetics. Adsorption data were fitted to linearly transformed Langmuir isotherm with R 2 (correlation coefficient) >0.99. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with Dubinin–Radushkevich isotherm.

Preparation and application of acrylic acid grafted polytetrafluoroethylene fiber as a weak acid cation exchanger for adsorption of Er(III)

In this work, a weakly acidic ion exchange fiber (PTFE- g-AA) has been prepared by 60Co irradiation grafting with acrylic acid (AA) onto the polytetrafluoroethylene (PTFE) fiber. The grafted fiber was characterized by FTIR, SEM and TGA technique. The exchange capacity of the PTFE- g-AA fiber is 3.87 mmol/g. The adsorbent material was employed for Er(III) uptaking by batch and column experiments. Kinetics studies showed that the adsorption process obeyed pseudo-second-order kinetics. The adsorption isotherms followed both the Freundlich model and Langmuir model. The maximum adsorption capacity of the PTFE- g-AA fiber for Er(III) was evaluated to be 142.0 mg/g for the Langmuir model. It was found that 0.75 M HCl–0.25 M NaCl solution provided effectiveness of the desorption of Er(III) from the PTFE- g-AA fiber. Various thermodynamic parameters such as standard enthalpy (Δ H 0), standard entropy (Δ S 0) and standard free energy (Δ G 0) were evaluated. The adsorption of Er(III) on the PTFE- g-AA fiber was found to be endothermic in nature. The Thomas model was successfully applied to experimental data to predict the breakthrough curves and to determine the characteristics parameters of the column useful for process design.

Flue Gas Carbon Dioxide Sequestration during Water Softening with Ion-Exchange Fibers

This study examines the use of ion-exchange fibers (IX fibers) to permanently sequester carbon dioxide present in flue gas into an aqueous phase as calcium or magnesium alkalinity while concurrently softening hard water. The only process inputs besides carbon dioxide (or flue gas) are snowmelt (or rainwater); no other chemicals are required for the regeneration of the IX fibers. Importantly, the process is not energy intensive and carbon dioxide does not need to be compressed to excessive pressures (>150psi) for efficient use. Sources of carbon dioxide do not require concentration and, therefore, the use of raw flue gas (∼17%CO2) is feasible with the rate of sequestration governed only by the partial pressure of carbon dioxide. While valid for flue gas obtained from any combustion process (e.g., coal, oil, natural gas, etc.), emissions from oil or gas combustion may be more appropriate for use in the described process due to the absence of mercury and particulates. It should also be noted that the presence of sulfur dioxide in flue gas would not adversely affect the process and may even enhance regeneration efficiency. The only product of the proposed process is an environmentally benign regenerant stream containing calcium and/or magnesium alkalinity. The unique property of IX fibers that makes the proposed process both environmentally sustainable and economically feasible is amenability to efficient regeneration with carbon dioxide and harvested snowmelt. Low intraparticle diffusional resistance is the underlying reason why IX fibers are amenable to efficient regeneration using snowmelt sparged with carbon dioxide; 95% calcium recovery was attained at a CO2 partial pressure of 6.8atm. On the contrary, commercial weak-acid ion-exchange resins in spherical bead forms are ineffective for regeneration with carbon-dioxide-sparged snowmelt due to extremely slow ion-exchange kinetics involving counter-transport of Ca2+ (or Mg2+) and H+. The energy balance for a typical electric utility shows that up to 1% of carbon dioxide emitted during combustion would be sequestered in the softening process.

In Vivo Assessment of Novel Furosemide Gastro-Mucoadhesive Delivery System Based on a Kind of Anion Ion-Exchange Fiber

A novel gastro-mucoadhesive delivery system based on a kind of anion ion-exchange fiber has been developed. Furosemide (FM), which is site-specifically absorbed from the upper gastrointestinal (GI) tract, was used as model drug. A novel-modified dissolution system, which can also be called “flow through diffusion cell,” was used to study the drug release from the drug fibers. The GI transit studies of the FM fiber complexes in rats and gamma imaging studies in volunteers were carried out to evaluate the gastro-mucoadhesive behavior of the fiber. The pharmacokinetic profile and parameters of the FM suspension and FM fiber in fasted and fed rats were measured, respectively. Studies on rats and volunteers provided evidence for the validity of the hypothesis that the drug fiber provided better gastro-mucoadhesive properties in vivo.

Sorption of perrhenate anions by lignin anion exchangers

The sorption of rhenium ions on high-permeability lignin ion exchangers was studied. The effects of the nature of functional groups in anion exchangers, the concentrations of the metal and an acid in solution, the pH of solution, and the time of sorption on recovery parameters were found. Conditions for the efficient separation of perrhenate ions from model sulfate solutions were determined. It was found that the new fibrous ion exchangers based on the natural polymer lignin were superior to AN-21, AN-18, and AV-16 synthetic anion exchangers based on the amino copolymers of styrene and divinylbenzene, which are commonly used for the sorption of rhenium ions, in sorption and kinetic characteristics.

Determination of vanadium(V) and chromium(VI) in a single sample on a fibrous ion exchanger disk

The determination of vanadium(V) and chromium(VI) in a single sample on a support disk was studied. Polyacrylonitrile fiber filled with an AV-17 anion exchanger was used as a solid phase. After adsorption, the elements were successively detected in the solid phase by color complexation reactions of vanadium with 8-hydroxyquinoline-5-sulfonic acid and chromium with 1.5-diphenylcarbazide. A procedure was developed for the adsorption-spectroscopic determination of 0.04–0.4 μg/mL vanadium(V) and 0.01–0.05 μm/mL chromium(VI) at V: Cr ratios of 1: 1 to 10: 1 in the dynamic mode. The limits of detections for vanadium and chromium were 0.04 and 0.005 μg/mL, respectively. It was shown that the background salt content of potable water had no appreciable effect; no preliminary sample preparation was required.

Selective Sensing of Multi-Inorganic Ions Using Ion Exchange Fiber Film

A biological and chemical sensor with a rapid response has been required for monitoring our health conditions and the purity of tap water for personal use. We have succeeded in the selective detection of multi-inorganic ions simultaneously using an ion-exchange fiber film. A kind of ion in a solution containing two kinds of cation could be detected by measuring the difference of adsorption force to the film. Moreover, we have succeeded in simultaneous sensing with concentrations as low as 10-5 mol/l using double layered films of cation and anion. Using the fiber film, we can easily achieve multi-layered structure stack and integration into the sensing devices. There is a high potentiality that the film is applicable to a high-performance device for biological sensing.

New nitrogen-and-phosphorus-containing fibrous ion exchangers for water treatment

New nitrogen-and-phosphorus-containing fibrous ion exchangers were produced by two-stage synthesis from Nitron fiber. The ion exchangers are efficient sorbents of heavy and nonferrous metals from aqueous solutions under dynamic conditions.

Synthesis, characterization and analytical applications of sodium dodecyl sulphate cerium (IV) phosphate: A new Pb (II) selective, surfactant-based intercalated fibrous ion exchanger

Sodium dodecyl sulphate-based cerium (IV) phosphate (SDS-CeP), a new Pb (II) selective intercalated fibrous ion exchanger, has been synthesized. It has been characterized on the basis of X-ray diffraction analysis, IR, thermo-gravimetric and differential thermal analysis, scanning electron microscopy (SEM) and ion exchange studies. The adsorption studies have also been carried out for some alkaline earths and heavy metal ions in different acidic media, showing a marked selectivity towards Pb (II), a toxic metal ion. Hence, its analytical utility has been established by achieving some binary separations on its column. The prepared material has shown good ion exchange capacity (2.92 meq/dry g basis), thermal stability and adsorption behaviour. The ion exchanger may play an explicit role in environmental studies.