Lewatit CNP Research Articles

Enhanced Lutetium Ion Sorption from Aqueous Solutions Using Activated Ion Exchangers.

The growing demand for rare earth elements (REE) requires the search for economically viable materials to efficiently recover REE from various solutions. Our research aims to investigate the potential of using a combination of the ion exchangers Lewatit CNP LF (in H+ form) and AV-17-8 (in OH- form) as an interpolymer system, "Lewatit CNP LF@AV-17-8" (X:Y), with varying mass ratios of X:Y to enhance the sorption efficiency of lutetium ions from nitrate solution. During the study, we used a range of analytical methodologies, including gravimetry, ultraviolet-visible (UV-VIS) spectroscopy, and inductively coupled plasma optical emission spectroscopy (ICP-OES). Our findings demonstrate that the interpolymer system "Lewatit CNP LF@AV-17-8" (X:Y), with a mass ratio of 4:2, exhibited a significantly enhanced sorption rate of Lu3+ ions (42%) compared to the individual Lewatit CNP LF (6:0) (25%) and the individual AV-17-8 (0:6) (21%) over a 48 h period. Moreover, this interpolymer system has demonstrated notable conformity to the Freundlich adsorption model, highlighting its performance as an effective sorbent for lutetium (III) ions. Notably, our study presents a novel utilization of the interpolymer system "Lewatit CNP LF@AV-17-8" (4:2), with an adsorption capacity of 221.05 mg/g, to enhance the recovery of lutetium ions. The research findings demonstrate its potential for enhancing the recovery of REE.

FEATURES OF THE SCANDIUM IONS INTERACTION WITH THE INTERPOLYMER SYSTEM LEWATIT CNP LF (H+ ) - AB-17-8 (OH- ) SYSTEM

The sorption of the interpolymer systems on the basis on Lewatit CNP LF and AB-17-8 industrial ion exchanges in the relation to scandium ions has been studied. The purpose of this research has been to study the sorption capacity of the interpolymer system “Lewatit CNP LF:AV-17-8” in relation to scandium ions. Methodology. To calculate the sorption parameters, the optical density of the solutions has been measured on the Jenway-6305 spectrophotometer. The obtained results have shown that the maximum sorption degree of the “Lewatit CNP LF:AV-17-8” interpolymer systems during 48 h of interaction has occurred in the molar ratios (3:3, 2:4 and 1:5) of polymers, the sorption degrees have been 26.4%; 27.9% and 26%, respectively. As can be seen, the value of the sorption degree is maximum at the ratio of 2:4. The value of the sorption degree in this ratio is higher by 32.5% and 28.5%, respectively, as compared with the degree of sorption of individual ion exchangers Lewatit CNP LF (6:0) and AV-17-8 (0:6).The highest values of the polymer chain binding degree after 48 h with scandium ions in the interpolymer system “Lewatit CNP LF:AV-17-8” for the ratios of 3:3; 2:4 and 1:5 have been 4.87%, 5.25% and 5.01%, respectively. The values of the polymer chain binding degree of the individual Lewatit CNPLF (6:0) and AV-17-8 (0:6) ion exchangers, after 48 h have been 3.68% and 4.26%, respectively. Conclusion. The obtained results have shown that the mutual activation of ion exchange resin the interpolymer system leads to a significant increase in their sorption capacity.

Enhanced Sorption of Europium and Scandium Ions from Nitrate Solutions by Remotely Activated Ion Exchangers.

The escalating demand for rare earth metals (REM) in situations of limited availability has spurred scientists to seek alternative sources of REM, such as industrial waste solutions. This paper investigates the potential for improving the sorption activity of readily available and inexpensive ion exchangers, specifically the interpolymer systems "Lewatit CNP LF and AV-17-8", towards europium and scandium ions, in comparison to the unactivated ion exchangers. The sorption properties of the improved sorbents (interpolymer systems) were evaluated using conductometry, gravimetry, and atomic emission analysis. The results demonstrate that the "Lewatit CNP LF:AV-17-8" (5:1) interpolymer system exhibits a 25% increase in europium ion sorption compared to the raw Lewatit CNP LF (6:0), and a 57% increase in europium ion sorption compared to the raw AV-17-8 (0:6) ion exchanger after 48 h of the sorption process. In contrast, the "Lewatit CNP LF:AV-17-8" (2:4) interpolymer system exhibits a 310% increase in scandium ion sorption compared to the raw Lewatit CNP LF (6:0), and a 240% increase in scandium ion sorption compared to the raw AV-17-8 (0:6) after 48 h of interaction. The improvement in europium and scandium ion sorption levels by the interpolymer systems, compared to the raw ion exchangers, may be attributed to the high ionization degree resulting from the remote interaction effect of the polymer sorbents as the interpolymer system in aqueous media.

Enantioselective desymmetrization of prochiral diesters catalyzed by immobilized Rhizopus oryzae lipase

The asymmetric hydrolysis of dimethyl 3-phenylglutarate 1 catalyzed by different immobilized preparations of Rhizopus oryzae lipase (ROL) has been studied. The Lewatit CNP 105 commercial support was activated to aldehyde groups (Lewatit-aldehyde) and used as a support for the immobilization of ROL using different strategies. Thus, the lipase immobilized in the presence of dithiothreitol at pH 7 (ROL-Lew-pH 7) was the most enantioselective catalyst for the hydrolysis of 1 at pH 7 and 25°C producing the (R)-monoester with an E value of 4.2 (ee=62%) whereas ROL immobilized at pH 10 gave only an E value of 1.1 (ee=4%). The medium engineering was also an interesting tool for improving the lipase selectivity. The addition of a solvent, combined with decreasing temperature improved the E value for the reaction from 4.2 to 24 (ee=62 to ee=92%). Finally, the application of the ROL-Lew-pH 7 preparation in the presence of 20% dioxane and 5°C allowed us to obtain the (R)-isomer of the monoester with an E value of 24 (ee=92%) in a 97% yield (of monoesters).

Regeneration dynamics of the carboxyl cation exchanger with sulfuric acid in the mode of loosening its layer

The paper presents the research results of the regeneration process of carboxylic cation exchanger Lewatit CNP 80, depleted in water softening, by sulfuric acid in the mode of loosening its layer. It has been established that the theoretical model of sorption intradiffusion dynamics adequately describes the regeneration process in this mode. The value of the effective kinetic coefficient of internal mass transfer does not vary in an increase of the expansion of the layer and coincides with this value in a dense layer.

H+-Na+ exchange dynamics on the caboxylic cation exchanger in the fluidized bed

We have investigated the H+-Na+ exchange dynamics in a mode of the fluidized bed on the carboxylic cation exchanger Lewatit CNP 80 at different values of the linear velocity of water filtration. We have found the conformity of the process of the H+-Na+ exchange dynamics in a mode of loosening the bed of the theoretical model of intradiffusion sorption dynamics. We have determined the value of the effective kinetic coefficient of internal mass transfer at different rates of passing the model solution. It has been established that this coefficient does not depend on the expansion of the bed and, accordingly, on the rate of passing the model solution and coincides with such in a dense bed.

Dynamics of the Na+-Ca2+ exchange on a carboxy cation exchanger

Nonequilibrium dynamics of the Na+-Ca2+ exchange in water softening on a Lewatit CNP 80 carboxylic cation-exchanger was studied at a widely varying linear velocity of water filtration. The kinetic coefficient of the pore-diffusion mass-transfer was determined at various flow rates of the model solution.

Fluidization of cation exchangers with regenerating sulfuric acid solution

Dependences of the bed expansion of cation exchangers (weakly acidic Lewatit CNP 80 and strongly acidic KU-2×8) on the flow velocity, temperature, and concentration of the regenerating sulfuric acid solution were determined. An equation describing the dependence of the bed expansion of cation exchangers on the flow velocity, temperature, and concentration of sulfuric acid, common to the two ion exchangers, was derived, which allows a priori determination of the extent of bed expansion in regeneration of cation exchangers in the fluidization mode.

Fluidization of ion exchangers by regeneration agents

We have established the relationships between the expansion of the layer of ion exchangers (weakly basic—Amberlite IRA 67, weakly acidic—Lewatit CNP 80, and strongly acidic—KU 2–8) and the rate, temperature, and concentration of regenerating agents (for anion exchanger—sodium hydroxide solution, for cation exchangers—sulfuric acid solutions). We have found the equations of the relationships between the expansion of the layer of ion exchangers and the rate, temperature, and concentration of regenerating agents, which makes it possible to a priori determine the mode of regeneration of ion exchangers in the fluidized layer.

H+-Ca2+ Equilibrium Exchange on Polyacrylic Cationites

Potentiometric titration curves of carboxyl-containing polyacrylic cation exchangers (Amberlite IRC 86, Dowex MAC 3, Lewatit CNP 80, Purolite C 104, and Relite CNS) in the H form with calcium ions were measured. It was found that the apparent equilibrium constant strongly depended on the composition of resinate solutions, which was indicative of significant deviations of solutions in the cation exchanger gel phase from the ideal behavior. The largest deviations were observed for Dowex MAC 3 ion exchanger, and the smallest, for Amberlite IRC 86. For the other sorbents, the dependences coincided to within measurement errors. The experimental data were treated in terms of six models of the theory of exchange equilibria. The best approximation to titration curves was obtained in terms of the model that suggested the presence of two types of exchange centers in ion exchangers and took into account the influence of the state of three neighboring fixed groups on each spatially separated center. The amounts of centers of all types in the ion exchangers were determined. Differences in the selectivity of the cation exchangers with respect to calcium ions were explained.

The H+-Ca2+ exchange on polyacryl cation exchangers

We have defined the curves of potentiometric titration of H-forms of carboxylic polyacryl cation exchangers (Amberlite IRC 86, Dowex MAC 3, Lewatit CNP 80, Purolite C 104, Relite CNS) with calcium ions. The values of parameters for exchange isotherms within computational errors coincide. The better approximation of the titration curves was achieved within the framework of a model implying the presence in ion exchangers of two types of exchange centers and taking into account the impact of three neighboring fixed groups for each spatially separated center.

Ion-exchange of Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+ ions from aqueous solution by Lewatit CNP 80

Removal of trace amounts of heavy metals can be achieved by means of selective ion-exchange processes. The newly developed resins offered a high resin capacity and faster sorption kinetics for the metal ions such as Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+ ions. In the present study, the removal of Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+ ions from aqueous solutions was investigated. Experimental investigations were undertaken using the ion-exchange resin Lewatit CNP 80 (weakly acidic) and were compared with Lewatit TP 207 (weakly acidic and chelating). The optimum pH range for the ion-exchange of the above mentioned metal ions on Lewatit CNP 80 and Lewatit TP 207 were 7.0–9.0 and 4.5–5.5, respectively. The influence of pH, contact time, metal concentration and amount of ion-exchanger on the removal process was investigated. For investigations of the exchange equilibrium, different amounts of resin were contacted with a fixed volume of Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+ ion containing solution. The obtained sorption affinity sequence in the presented work was Ni 2+ > Cu 2+ > Cd 2+ > Zn 2+ > Pb 2+. The metal ion concentrations were measured by AAS methods. The distribution coefficient values for metal ions of 10 −3 M initial concentration at 0.1 mol/L ionic strength show that the Lewatit CNP 80 was more selective for Ni 2+, Cu 2+ than it was for Cd 2+, Zn 2+ and Pb 2+. Langmuir isotherm was applicable to the ion-exchange process and its contents were calculated. The uptake of metal ions by the ion-exchange resins was reversible and thus has good potential for the removal of Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+ from aqueous solutions. The amount of sorbed metal ion per gram dry were calculated as 4.1, 4.6, 4.7, 4.8, and 4.7 mequiv./g dry resin for Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+, respectively. Selectivity increased in the series: Cd 2+ > Pb 2+ > Cu 2+ > Ni 2+ > Zn 2+. The results obtained showed that Lewatit CNP 80 weakly acidic resin had shown better performance than Lewatit TP 207 resin for the removal of metals. The change of the ionic strength of the solution exerts a slight influence on the removal of Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+. The presence of low ionic strength or low concentration of NaNO 3 does not have a significant effect on the ion-exchange of these metals by the resins. We conclude that Lewatit CNP 80 can be used for the efficient removal of Pb 2+, Cu 2+, Zn 2+, Cd 2+, and Ni 2+ from aqueous solutions.

Deionization of water for small factories or laboratories by a four-stage ion-exchange device

Deionization of water by a small singe-body device with four-stage ion-exchange processes for production of deionized water for laboratory analyses (according to BDS ISO 3696 and BS 3978) or small factories was studied. Four ion-exchange processes were performed in a single filter body: cation exchange by weak acid cation exchanger Lewatit CNP 80; cation exchange by strong acid cation exchanger Lewatit S 100; anion exchange by weak base anion exchanger Lewatit MB 64; anion exchange by strong base anion exchanger Dowex SBR. Conventional water treatment ion exchange plants use the same four processes but in more than one filtration body (minimum two). Besides, they need at least 12 valves for water and regeneration flows redistribution and quite a large space for technological localization and service. The small water treatment ion exchange device developed is compact compared to the conventional ones and has only 4 valves.

Behaviour of Cadmium(II) Ions on Cation-Exchange Resins

Cadmium is one of the most toxic heavy metals known and is considered inessential for living organisms. This element is found at low concentrations in natural environments, but human activities have led to increased levels in all continents. In the present study, the removal of cadmium(II) ions from aqueous solutions was investigated. Experimental investigations were undertaken using the ion-exchange resins Amberlite IR 120 (strongly acidic), Amberlite IRC 718 (weakly acidic and chelating), Lewatit TP 207 (weakly acidic and chelating) and Lewatit CNP 80 (weakly acidic). For investigations of the exchange equilibria, different amounts of resin material were contacted with a fixed volume of a cadmium ion-containing solution. Because the uptake of cadmium ions was mainly dominated by the pH of the liquid phase, the pH value was varied between 0 and 3 with sample sizes of 0.5-5.0 g in each series studied. The initial and final cadmium ion concentrations were measured by ICP-AES methods. Exchange equilibria we...

Studies of H+-Mg2+ and H+-Ca2+ Exchanges on Acrylic Carboxylic Cationites from the Viewpoint of the Exchange Equilibrium Theory

The sorption of Mg2+ and Ca2+ ions by the H-form of the acrylic carboxylic cationite Lewatit CNP 80 as the magnesium sulphate or calcium chloride concentration in the external solution was varied by two orders of magnitude has been considered from the viewpoint of the ion-exchange equilibrium theory. The experimental data were obtained using a method which provided high precision measurements of the potentiometric titration curve over a wide range of resinate compositions for the ionite gel phase. The strong dependence of the effective equilibrium constant on the resinate solution composition was described satisfactorily by the exchange equilibrium theory. The selectivities towards Ca2+ and Mg2+ ion sorption by the H-type of carboxylic cationite studied were close. An explanation for this phenomenon was proposed.

Clean Ion-Exchange Technologies. 3. Temperature-Enhanced Conversion of Potassium Chloride and Lime Milk into Potassium Hydroxide on a Carboxylic Ion Exchanger

This paper reports the results obtained by studying the ion-exchange synthesis of potassium hydroxide from lime milk and carboxylic resin Lewatit CNP 80 in the K-form. Carboxylic resin has been shown to have several advantages in comparison with, for example, sulfonate ion exchanger, due to its higher selectivity toward Ca2+, which substantially enhances at elevated temperature. The increase of temperature from 293 to 333 K enhances the sorption of Ca2+ versus K+ that allows achieving far higher KOH concentration in the solution phase. The values of equilibrium separation factor, α, for Ca2+−K+ exchange have been determined at 293 and 333 K by varying the equivalent fraction of Ca2+ in the solution phase from 0.04 to 0.7. A remarkable increase of α values has been observed at higher temperatures and at low calcium content in the solution phase. The regeneration of the resin (conversion from Ca- to K-form) has been carried by using the mixtures of potassium chloride and potassium sulfate. The regeneration ...