Gel-type Cation Exchange Resin Research Articles

Potential of Cation Exchange Resin as a Carrier for Anaerobic Consortia in Biohydrogen Fermentation

Cation exchange resin (CER) has been reported to promote sludge fermentation. However, previous studies have typically focused on the effects of CER on sludge properties to enhance fermentation, and the role of CER as a biocarrier for anaerobic consortia during fermentation has been overlooked. Thus, in this study, the potential of gel-type and macro-reticular type CERs to serve as biocarriers in fermentation was investigated. A significant number of anaerobes appeared to be attached to the surfaces of CER during 2-day fermentation. However, an extended fermentation time negatively affected the attachment of anaerobic consortia, suggesting that CER may be a suitable carrier for short-term fermentation processes, such as biohydrogen fermentation. Electrochemical analyses revealed that the electron transfer capacities of CER with attached anaerobes were enhanced after both 2-day and 28-day fermentation periods, with the macro-reticular type CER exhibiting higher electron transfer capacity than the gel-type CER. Fermentation experiments using mixing model substrates with macro-reticular and gel-type CERs with attached anaerobes showed that the macro-reticular type CER was more beneficial for biohydrogen fermentation than the gel-type CER. Further analyses of microbial communities revealed that hydrogen-producing bacteria (i.e., Caloramator, unclassified_f_Caloramatoraceace, and Sporanaerobacter) were more likely to adhere to the macro-reticular type CERs. This outcome confirmed that macro-reticular type CERs have significant potential as a carrier for anaerobic consortia to promote the generation of hydrogen and volatile fatty acids. These findings are expected to provide a reference for using materials as biocarriers to enhance the biohydrogen fermentation of sludge.

Biodiesel production using gel-type cation exchange resin at different ionic forms

In this study, a strong acidic-type cation exchange resin was used in the transesterification of corn oil to fatty acid methyl esters (FAME). The gel-type cation exchange resin (Purolite-PD206) was used in H+ and Na+ forms to utilize ion-exchange resin as effective heterogeneous catalyst in the production of biodiesel. Effect of ionic forms of ion exchange resin on free fatty acid (FFA) conversion and composition was investigated by using different amounts of ion exchange resin (12, 16, and 20 wt%), various mole ratios of methanol to oil (1:6, 1:12, and 1:18 mol/mol), reaction temperatures (63, 65, and 67°C), and reaction time (24, 36, and 48 h) during transesterification reaction. The highest FFA conversions of 73.5% and 79.45% were obtained at conditions of 20 wt% of catalyst, 65°C of reaction temperature, 18:1 as methanol to oil ratio, and 48 h of reaction time for H+ and Na+ forms of ion exchange resin, respectively. These results were obtained from regression equations established by using analysis of variance (ANOVA) model according to the experimental results of selected parameters. Gas chromatography analysis revealed that FAME is mainly composed of C16:0 (palmitic), C18:1 (oleic), and C18:2 (linoleic) acids of methyl ester.

High throughput development of one carbon molecular sieve for many gas separations

A set of CMS adsorbents was synthesized by pyrolyzing gel-type cation exchange resins (IERs) based on sulfonated poly(styrene-co-divinylbenzene). Fifteen different materials were synthesized following a design of experiments (DOE) that included variations on four factors. These factors were divinylbenzene (DVB) content, plus three factors associated with pyrolysis (peak temperature, hold time, and temperature ramp rate). Results revealed that the peak temperature has a significant impact on the micropore volume and the effective pore size of the resultant CMS adsorbents, but the other three input variables have very little impact. High throughput single gas adsorption was conducted on the fifteen CMS adsorbents using nine probe gas molecules: CO2 (kinetic diameter 3.3Å), N2 (3.64Å), CH4 (3.8Å), C2H4 (3.9Å), C3H6 (4.0Å), C2H6 (4.1Å), C3H8 (4.3Å), i-C4H10 (5.0Å), SF6 (5.5Å). Based on gas pair selectivities calculated from the single gas adsorption data, pyrolysis process boundaries were defined to make suitable CMS adsorbents with effective micropore size in the range of 3.5–4.6Å. Based on the high throughput findings, four additional CMS adsorbents were produced for the industrially significant separations: C3H6/C3H8, C2H4/C2H6, N2/CH4, and CO2/N2. Breakthrough performance of the four target gas pairs was characterized in a packed bed configuration using binary gas mixtures of the four target gas pairs. The four CMS adsorbents exhibited high separation factors, 43 for C3H6/C3H8, 10 for C2H4/C2H6, 9 for N2/CH4, and 12 for CO2/N2, illustrating the validity of the high throughput results.

Sulfate ion (SO4(2-)) release from old and new cation exchange resins used in condensate polishing systems for power plants.

In this study, a dynamic cycle test, a static immersion method and a pyrolysis experiment were combined to examine the characteristics of SO4(2-) released from several new and old cation exchange resins used in condensate polishing systems for power plants. The results show that the quantity and velocity of SO4(2-) released from new and old resins tend to balance in a short time during the dynamic cycle experiment. SO4(2-) is released by 1500H (monosphere super gel type cation exchange resins) and 001 × 7 (gel type cation exchange resins) new and old cation exchange resins, the quantity of which increases according to immersion time. In the pyrolysis experiment, the quantity of SO4(2-) released from resins increases and the pH of the pyrolysis solution transforms from alkaline to acidic with an increase in temperature.

Separation of fructose and glucose from date syrup using resin chromatographic method: Experimental data and mathematical modeling

In this work a series of experiments have been performed to study and simulate the separation of glucose and fructose as the most applicable sugars in the food industry. The objective of this work is understanding and modeling the behavior of these components in a chromatography column when they are introduced to the column as simple components, binary solutions, and also as the major species in date syrup. The column's diameter and height are 3.5 cm and 15 cm respectively, and Purolite PCR642Ca, which is an acidic gel-type cation exchange resin (Ca 2+), was used for the separation of sugars. Static method was applied to determine the equilibrium constants, and frontal (dynamic) analysis method was used to determine the mass transfer coefficients at two different temperatures of 30 and 60 °C for single and multi-component mixtures for a solution with a sugar concentration of 70 g/L. The kinetic studies for the prediction of mass transfer coefficients were performed according to the breakthrough curves by a linear driving force approximation (LDF), while the adsorption isotherms were estimated by linear model. Adsorption equilibrium constants and mass transfer coefficients between fructose, glucose and solid resin were determine by optimization procedure. The results of the optimization and parameter estimation for synthetic sugar solutions were also applied for modeling the separation of sugars in date syrup. The predicted results of the real mixtures (date syrup) have a good agreement with the experimental data and show that both sugars can be separated successfully by this method.

Evaluation of sugar sorption isotherm measurement by frontal analysis under industrial processing conditions

This paper evaluates frontal analysis for routine sugar isotherm measurements at industrial conditions, that is concentrations up to 400 kg/m 3 and a temperature of 60 °C. Sugar isotherms for a gel type cation-exchange resin loaded with metal ions were measured in a HPLC set-up equipped with a UV detector. It is shown experimentally that isotherms obtained with large concentration steps (step series method) underestimated the isotherm. The underestimation is larger for larger resin particle size. In contrast, isotherms obtained with small concentration steps (staircase method) yielded correct isotherms. The seldom-mentioned change of the sorbent volume during the course of an isotherm measurement is discussed. It is shown that shrinking of 4% cross-linked resin at high sugar concentration has a negligible effect on the isotherm. Furthermore, the isotherms obtained with staircase frontal analysis agreed very well with those obtained with the independent, though more laborious and time-consuming, adsorption–desorption method. Staircase frontal analysis is shown to be convenient and accurate and is therefore recommended for isotherm measurements covering large concentration ranges.

Dynamics of Sodium and Lithium Counter-Ions and Water Molecules in Cation-Exchange Resins as Shown by NMR Spectroscopy

The dynamics of water molecules and cations (lithium and sodium counter-ions) in cation-exchange resins were investigated by measuring relaxation time and self-diffusion coefficients of 1H, 7Li, and 23Na NMR. Five gel-type cation-exchange resins with different by the crosslinked poly(styrene sulfonic acid) copolymer swollen in water and salt aqueous solution were studied. A macroporous-type resin was studied for comparison. Activation energy for the lithium and sodium ions obtained from the Arrhenius plots of spin-lattice relaxation times T1 correlated well with the cross-linking of resins. Since T1 of the cations in every resin are shorter than in corresponding aqueous solution, the correlation time of the rotational motion of cations is longer in the resins. With higher cross-linking of the resin, the rotational motion of the cations becomes slower and more restricted. Self-diffusion coefficients of water molecules and lithium and sodium counter-ions in the gel-type resin were directly measured by pulsed field-gradient NMR methods. Translational diffusion of these species was closely related to the cross-linking of resin similar to T1. The diffusion of water molecules and cations becomes slower in higher cross-linked resin. Apparent diffusion coefficients of Li+ ions and water molecules were dependent on diffusion time. This may be explained by restricted diffusion in a three dimensional network structure of gel-heteroporous type ion-exchange resins.

Reasons for deactivation of unpromoted polymeric catalysts in bisphenol A synthesis

Quantitative speciation of sulfonic groups and compositional analysis of gel-type cation-exchange resins used as unpromoted catalysts in bisphenol A synthesis, deactivated at the commercial plant, were carried out. It was proved that building-in the polyphenol-type high-molecular-weight compounds, formed inside the catalyst grains, into the catalyst polymeric matrix is the basic reason for deactivation of the catalyst. It was found that the rate of formation of these polyphenols is only to a small degree dependent on the concentration of bisphenol A synthesis by-products in the reaction mixture circulated through the fixed catalyst bed.

Lewis Acid-Base Properties of a Gel-type Cation Exchange Resin

Gel-type cation exchange resins like SK-1B are based on DVB-crosslinked polystyrene with sulfonic acid functional groups. The behavior of some conjugate acid-base pairs was studied and explained in terms of Lewis and Pearson Acid-Base Theories. The application of these resins as a no contaminant medium for pH regulation has special interest in biological systems and is not limited to water conditioning like deionization or dealkalization.

Crud Removal Performance with Ion Exchange Resins in BWR Plants.

It is needless to say that one of the most important roles of the condensate demineralizer in Japanese boiling water reactors (BWR) is to eliminate such impurities during accidental occurrence of sea water leakage from condensate cooling system. Ion exchange resins packed in condensate demineralizer have also been expected to decrease crud, or corrosion products (CP) in condensate water in order to finally reduce activated corrosion products (ACP) in the reactor coolant loop.It is perceived that crud removal ability of a condensate demineralizer has been improved year by year. And we call this phenomenon as “Aging Effect”. Typical property changes of aged cation exchange resin consisted of an increase of water retention capacity and a change of surface texture. Based on these findings, we formulated a new concept and developed new gel type ion exchange resins for the better crud removal.The results from column tests using actual condensate water for approximately three years and full scale test at an actual condensate polisher from Sep. 1993 showed that a gel type cation exchange resin having 6% crosslinkage produced excellent crud removal performance and low leaching rate of total organic carbon.

Studies on the uptake of Th(IV), U(VI) and Pu(IV) on Dowex 50WX8 resin from TBP-Shell Sol-T mixtures

Batch equilibration studies have been carried out to understand the uptake of Th(IV), U(VI) and Pu(IV) on a conventional gel type cation exchange resin, Dowex 50WX8, from TBP-Shell Sol-T mixtures containing different amounts of nitric acid. Based on the results of the equilibration studies, column experiments have been carried out and conditions optimized to achieve separation of these elements present in binary and ternary mixtures. The influence of water content of the resin phase and the nature of the exchanging cation on the extent of uptake has also been investigated.

Radiation stability of macro-porous and gel-type cation exchangers

Macro-porous cation exchange resin Diaion CPK-08 and gel type cation exchange resin Dowex 50WX8 were irradiated with γ-rays from60Co, while soaked in distilled water, 0.5M HNO3 or 4M HNO3, and the ion-exchange properties, such as strong- and weak-acid capacities, moisture content and wet resin volume, were examined in relation to absorbed dose. There was no appreciable difference between the radiation stabilities of the two cation exchangers. Increase of HNO3 concentration reduced the loss of strong-acid capacity and increased the decross-linkage and the weak-acid capacity. Elution characteristics of137Cs and90Sr from columns packed with γ-irradiated resin were examined and the column distribution ratio of these radionuclides and the theoretical plate number were calculated. These values decreased with the increase of absorbed dose. Diaion CPK-08 was packed into a pressurized column and irradiated with γ-rays at a dose rate of 2·106 R/hr, while water was passed through the column at a constant flow rate. The greatest change of the resin properties was observed at an upper stream position from the position of the highest radiation dose of 2·106 R/hr.

Thin juice deliming with gel type cation exchange resins

Thin juice deliming with gel type cation exchange resins