Adsorption of Acidic Impurities From Organic Esters Using Basic Ion Exchange Resins as Functionalized Polymers

Abstract

Sorption of acidic impurities from diethyl phthalate and butyl acetate using basic resins, bearing tertiary amino groups on a styrene‐divinylbenzene macroporous matrix, has been investigated for purification of the esters. The equilibrium studies show selective sorption of the acidic impurities and a high loading capacity (in the range of 2.2–5.3 mol/kg of dry resin) even at millimolar acid concentrations. The uptake of the acids is assisted by specific Lewis acid‐base interaction with the functional group of the resins. The interaction leads to formation of a hydrogen bonded complex between the acidic proton and the lone pair of electrons on the nitrogen of the amino group. The sorption studies have also been performed in ethanol and butyl alcohol to evaluate their use for the regeneration of the resins and recovery of the acids. The sorption data have also been analyzed using extended Flory‐Huggin theory of polymer solutions to determine the interaction parameters between different components.     

有机羧酸在弱碱性树脂上的吸附平衡

引　言有机羧酸是重要的化工原料 ,在化工、染料、食品及医药等领域有着广泛的用途 .有机羧酸的重要制法之一是发酵法 ,其特点是原料的利用及转化率较高 ,而分离费用一般占整个产品成本的 50 %～60 % [1].例如 ,乳酸发酵液中除乳酸和葡萄糖外还有乙酸、丁二酸、酒石酸、柠檬酸等常见的有机羧酸 ,其中约含乳酸 3.5%、乙酸 1 .0 % .此外 ,发酵法制备乳酸存在着明显的产物抑制现象 ,发酵液中的乳酸浓度过高将直接影响过程速率 .选择新的有机羧酸分离方法 ,保证在有利于发酵过程的条件下有效地分离发酵液中的有机羧酸 ,已经成为近年来稀溶液分离…     

Synthesis,Characterization, and Evaluation of Gel‐Type Poly(4‐Vinylpyridine) Resins for Plutonium Sorption

Abstract

Three different cross‐linked (4, 8, and 12%) gel‐type strong‐base poly(4‐vinylpyridine) resins (PVP) have been synthesized and characterized by elemental analysis, IR, exchange capacity, and moisture content. The uptake of plutonium and uranium was measured as a function of nitric acid concentration using all the three PVP resins. Plutonium sorption and elution kinetics experiments were also performed on all three PVP resins and compared with the benchmark, a gel‐type quarternary ammonium type anion‐exchange resin. The plutonium sorption rate decreases with the increase in cross‐linkage of the resin. All the three PVP resins exhibit better elution kinetics compared to the benchmark. The results on kinetic experiments performed on all three‐gel‐type resins indicated 8% gel‐type PVP resin with 50–100 mesh as a better candidate for plutonium processing or purification. Radiation degradation studies were carried out on the 8% PVP resin by gamma irradiation up to 200 MRad. The irradiated resins were characterized by IR, TGA, and SEM.

The exchange capacity, moisture content, and plutonium uptake were also evaluated for the irradiated PVP resins in comparison with the benchmark. The results indicated a better radiation stability for PVP resin over the benchmark.     

Evaluation of New Anion Exchange Resins for Plutonium Processing

Abstract

This paper presents the results of studies comparing the performance of two new anion exchange resins for plutonium processing with the well proven and widely used benchmark, Dowex 1X4 resin. In this connection, the experiments on distribution ratio measurement of plutonium as a function of nitric acid concentration, Pu(IV) sorption kinetics, chemical, thermal, and radiation degradation of the two commercially available anion exchange resins namely, Tulsion A‐PSL 4 and Tulsion A‐PSL 6 have been studied, vis‐à‐vis the benchmark. Tulsion A‐PSL 6 was found to have higher plutonium sorption capacity and polymer matrix stability as well as better kinetics of sorption than the other two resins, while Tulsion A‐PSL 4 and Dowex 1X4 were found to have comparable sorption capacity, kinetics, and resistance to chemical and radiation degradation. The small‐scale evaluation of these new anion exchange resins shows that they can be used for the purification and concentration of plutonium.     

The Effect of Degree of Impregnation in Amberlite Resins with Organophosphorous Extractants for Y(III), La(III), Ce(III), Th(IV) and U(VI) Ions

Abstract

Background: The sorption of Y(III), La(III), Ce(III), U(VI) and Th(IV) ions with solvent impregnated resins using diphenylphosphate (DPP), and diphenylphosphinic acid (DPPA) as extractant and Amberlite XAD 16 and Amberlite XAD 2000 as a polymeric support has been studied. The impregnated resins containing various amounts of extractants (10/90, 20/80, 50/50, 60/40) have been prepared by a dry method. The effects of pH, types of extractant, extractant content, surface area of polymeric support and contact time have been investigated by batch method.

Results: The impregnation for DPP on XAD‐16 and XAD‐2000 was 111 and 46% at 60/40 extractant/resin mass ratio, respectively. The impregnation of DPPA at all ratios on both resins was found constant and lower than DPP. The sorption percentage of studied metal ions was within 90‐99% for DPP and DPPA on both resins after 20/80 extractant/resin mass ratio.

Conclusions: The sorption of DPP on Amberlite XAD 16 and XAD 2000 resins is rather more than DPPA. It could be seen that 20/80 extractant/resin mass ratio is generally adequate for single metal analysis where 60/40 could be suitable for multi‐metal analysis.     

Diffusion of Aggressive Media in Hydrophilic Polymers

Abstract

The simultaneous sorption and diffusion of acid and salt in polyvinylalcohol are considered under conditions of polymer swelling. Obtained data on water sorption by PVA show an anomalous mechanism of the transport of solvent in this kind of polymer. The analysis of equilibrium sorption of an acid-salt mixture shows that interactions of polymer OH groups with hydrogen ions of hydrogen chloride lead to a decrease in salt solubility in the polymer. The theory of Donnan equilibrium was used to solve the problem of the sorption of the acid-salt mixture as well as to create the boundary conditions for a proposed mathematical model of the transport of the buffer mixture.

Methods of determining parameters of the buffer mixture transport in hydrophilic polymers have been created and physicochemical characteristics of investigated multicomponent system are calculated on the basis on these methods.     

Zirconium and Hafnium Separation,Part 2. Solid/Liquid Extraction in Hydrochloric Acid Aqueous Solution with Anion Exchange Resins

Abstract

Sorption behavior of zirconium and hafnium on different commercial anion exchange resins with different amine functions; ammonium (Amberjet 4200Cl), pyridine (PVP) and pyridinium (HPQ) was investigated in hydrochloric acid by both batch and column methods. Experiments were studied as a function of the concentration of hydrochloric acid. For all resins, zirconium was preferably extracted. The highest separation factors at equilibrium conditions were obtained by poly(vinyl‐pyridine) (PVP) with a hydrochloric acid concentration of 9.5 M. It was observed that a single contact of the loaded resins with pure water completely back extracted the metal ions from the resins. On the basis of the significant difference between distribution coefficients of Zr and Hf, the separation was performed on a glass column (25×160 mm), packed with the resin. The breakthrough curves showed a competitive sorption and desorption process between Zr and Hf for the three resins studied.     

Selective Solubilization of Nitrophenols and Adsorption on Ion Exchange Resins in Nonaqueous Conditions

Abstract

Separation of nitrophenols (NP) has been studied by selective solubilization in organic solvents of different polarities. o‐NP dissolves very well in heptane and toluene while intermolecular hydrogen bonding among p‐NP molecules decreases its solubilization in these solvents. Thus partial separation of o‐/p‐nitrophenols is achieved by selective solubilization of o‐NP in heptane. The trace amounts of p‐NP from the o‐NP solutions are removed by its selective sorption on basic ion exchange resins. The sorption of nitrophenols, individually and in mixtures, is experimentally determined from their solutions in heptane, toluene, and methanol by using weakly basic Indion‐850 and Duolite A‐308 resins and strongly basic Indion‐810 resin. The equilibrium adsorption studies show very selective adsorption of p‐NP from heptane with a high loading capacity on Indion‐850.     

Modelling the sorption of water-ethanol mixtures in cross-linked ionic and neutral polymers

Water-ethanol sorption in strong sulfonated polystyrene cation-exchangers, in weak acrylic cation-exchangers and in neutral cross-linked dextran gels as well as their elastic properties have been measured. The effect of polymer matrix and cross-link density have been studied. The ionic resins were mainly in the Na⁺ form. The data have been analyzed by means of thermodynamic mixing models based on the Flory-Huggins equation, quasi-chemical UNIQUAC and non-random factor equations. The elasticity of the polymer networks was incorporated in the models as an additional free energy term and two elastic models derived for non-ideal networks were tested.The quasi-chemical approach using the non-random factors proved to be the best choice for calculating the mixing effects in the sorption equilibrium model. Experimental shear modulus data showed that the elastic properties of the ionic resins can be described adequately only by the model which takes into account the limited extensibility of the polymer chains. The elastic parameters estimated from the modulus data were used in the equilibrium model and a semi-quantitative correlation with the sorption data was obtained.Both the experimental data and modelling results indicated that the studied materials respond distinctly differently to the external solvent composition and have characteristic sorption properties. The polymer matrix type and ionic group density had clear effects on the phase transitions from gel-like to glassy polymer in different aqueous ethanol mixtures. Furthermore, the hydrophilicity and the water selectivity depended strongly on the polymer type. The acrylic acid resin was the most hydrophilic and had also the highest water selectivity. The water selectivity of the sulfonated PS-DVB resins and the dextran gels was approximately equal.     

Production of L‐lactic acid by Lactobacillus delbrueckii in chemostat culture using an ion exchange resins system

L ‐Lactic acid production from beet molasses by Lactobacillus delbrueckii CECT 286 in a continuous fermenter‐ion exchange resins system has been investigated and compared with that observed in a conventional chemostat. The principle of this method is to remove the lactate during the course of fermentation as it is formed by adsorption to an anion exchange resin (Amberlite IRA‐420) in the carbonate form and to overcome its inhibitory effects on lactic acid bacteria by maintaining low lactate concentrations in the medium. Ammonium lactate was formed by percolating ammonium carbonate solution through this resin and it was converted to lactic acid by treatment with a cation exchange resin (Amberlite IR‐120) in hydrogen form. Compared with a conventional chemostat, this fermentation–ion exchange resins system enhanced the fermentation, controlled the pH, and showed the remarkable effect of increasing the yields of lactic acid from sucrose and biomass from sucrose due to the complete utilization of sucrose. © 1999 Society of Chemical Industry     

Metal ion adsorption behavior of poly[3‐(dimethylamine)propyl acrylate] and poly[3‐(dimethylamine)propylacrylate‐co‐acrylic acid] resins

Two resins were synthesized by radical polymerization using N,N′‐methylene‐bis‐acrylamide and ammonium persulfate as the crosslinking reagent and initiator, respectively. The yields were 98%. The resins were characterized by FTIR and UV‐Vis spectroscopy. Sorption behavior of resins toward Hg(II), Cd(II), Zn(II), Pb(II), and Cr(III) ions was studied at different pHs depending on the metal ion. Both resins showed selective sorption to Hg(II) ions at pH 2 from a mixture of all ions.The elution of Hg(II) bound to the resins was also investigated using perchloric acid at different concentrations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1251–1256, 2002; DOI 10.1002/app.10455     

Removal of Cr(VI) Oxy‐anions from Aqueous Solution by Sorption into Poly(Acrylamide‐Co‐Maleic Acid) Hydrogels

Abstract

The dynamic removal of hexavalent chromiuim by poly(acrylamide‐co‐maleic acid) hydrogels was studied by a batch equilibrium technique at 35°C. Various kinetic and adsorption parameters such as rate constant for sorption, intraparticle diffusion rate constant, Langmuir constant, and adsorption capacity have been evaluated. The sorption process follows the Langmuir‐type behavior and extent of sorption of Cr(VI) ions depends upon the composition of co‐polymeric gels, presence of other ions in the solution, and temperature of the system. Relatively higher temperature favors the sorption process. The activation energy was found to be ?20.369 kJ mol^?1. Finally, various thermodynamic parameters have also been calculated to elucidate the mechanism involved in the sorption process. The positive enthalpy change indicates the endothermic nature of the process. The presence of fluoride ions causes a decrease in the degree of sorption of Cr(VI). Finally, the sorption of Cr(VI) into the copolymeric sorbent has been explained on the basis of coordination between electron rich O and N atoms of sorbent molecules and the Cr(III) molecules. Moreover, H‐bonding interactions also seem to contribute to the sorption process.     

Adsorption of lactic acid onto three ionic liquid‐modified porous polymers

Three ionic liquid (IL)‐modified porous polymers were synthesized and used for the adsorption of lactic acid. The experimental adsorption kinetics and equilibrium data from the IL‐modified polymers were obtained. The kinetic study revealed a low temperature to be advantageous to the adsorption process. The dependence of the level of lactic acid adsorption on the amount of polymer, initial lactic acid concentration, and pH was examined at equilibrium. The maximum efficiency was obtained using the maximum adsorbent dose. A comparison of lactic acid adsorption at different pH revealed anion exchange to be the main interaction between the lactic acid and polymers, not molecular adsorption. The amounts adsorbed were fitted to the Langmuir, Freundlich, and Temkin equations. The equilibrium data for modified polymers (imidazole modified polymer, methylimidazole modified polymer, and ethylimidazole modified polymer) were best represented by the Langmuir and Freundlich isotherm with R² values of 0.99. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Treatment of wastewater containing Pb and Fe using ion‐exchange techniques

Treatment of wastewater containing lead and iron was examined using two different ion‐exchange resins namely Duolite ES 467 (containing amino‐phosphonic functional groups) and a chelating ion‐exchange resin (containing hydroxamic acid functional groups). Initially different sorption parameters such as contact time, pH, concentrations of sorbent, sorbate and chloride ion were studied. The sorption kinetics was observed to be fast and equilibrium could be reached within 30 min. Lead sorption efficiency increased with increase in pH whereas the opposite trend was observed with iron. The presence of chloride ions greatly reduced the Pb sorption efficiency in the case of Duolite ES 467. Column studies were carried out to recover Pb and Fe individually using Duolite ES 467 resin. The maximum uptake of Pb at pH 2 and 3 was observed to be 11.63 and 33.96 g dm^?3 of resin respectively. Similarly, for Fe at pH 2 and 3 the uptake was observed to be 10.07 and 6.96 g dm^?3 of resin respectively. In the presence of chloride ions, column studies were carried out using Duolite ES 467 for iron and chelating ion‐exchange resin containing hydroxamic acid functional groups for lead sorption. Hydroxamic acid resin's loading capacity remains constant for at least up to 20 cycles. Copyright © 2005 Society of Chemical Industry     

Synthesis and characterization of biodegradable lactic acid‐based polymers by chain extension

BACKGROUND: Poly(lactic acid) (PLA), coming from renewable resources, can be used to solve environmental problems. However, PLA has to have a relatively high molecular weight in order to have acceptable mechanical properties as required in many applications. Chain‐extension reaction is an effective method to raise the molecular weight of PLA. RESULTS: A high molecular weight biodegradable lactic acid polymer was successfully synthesized in two steps. First, the lactic acid monomer was oligomerized to low molecular weight hydroxyl‐terminated prepolymer; the molecular weight was then increased by chain extension using 1,6‐hexamethylene diisocyanate as the chain extender. The polymer was characterized using ¹H NMR analysis, gel permeation chromatography, differential scanning calorimetry and Fourier transform infrared spectroscopy. The results showed that the obtained polymer had a M_n of 27 500 g mol^?1 and a M_w of 116 900 g mol^?1 after 40 min of chain extension at 180 °C. The glass transition temperature (T_g) of the low molecular weight prepolymer was 47.8 °C. After chain extension, T_g increased to 53.2 °C. The mechanical and rheological properties of the obtained polymer were also investigated. CONCLUSION: The results suggest that high molecular weight PLA can be achieved by chain extension to meet conventional uses. Copyright © 2008 Society of Chemical Industry     

Sorption of Citric Acid from Aqueous Solutions by Macroporous Resins Containing a Tertiary Amine Equilibria

Abstract

Experiments were conducted on equilibrium distribution of citric acid between relatively concentrated aqueous solutions and macroporous resins containing tri-n-octylamine (TOA). The equilibrium data were well described by the Langmuir isotherm equation. Chemical model analysis of the results showed that the sorption could be also explained by the formation of an acid-amine complex with general composition (acid)(TOA)_q in the resin phase. The loss of amine from the impregnated resins and the effect of temperature on equilibrium distribution were also discussed.     

Studies on the Sorption of Palladium using Cross‐Linked Poly (4‐Vinylpyridine‐Divinylbenzene) Resins in Nitric Acid Medium

Various cross‐linked (4, 8, and 12%) gel‐type weak‐base poly(4‐vinylpyridine) (PVP) resins were studied for palladium recovery from nitric acid medium. The sorption of palladium was found to decrease with an increase in cross‐linkage of the resin. 8 and 12% PVP resins exhibited maximum D _Pd(II) values at 2–6 M HNO₃, whereas 4% PVP resin showed maximum D _Pd(II) values at lower acidities (0.1 M HNO₃). FT‐IR, SEM, and XPS techniques were used for the characterization of palladium‐loaded resins. Detailed studies were carried out with the resin of modest cross‐linkage i.e., 8% PVP resin. The sorption isotherm studies revealed that the maximum palladium loading approaches the theoretical capacity of the resin, presuming the sorption of palladium as divalent anion at 4 M HNO₃. The pseudo‐second order kinetics model yielded the best fit for the experimental data of sorption kinetics. An increase in temperature accelerates the rate of palladium extraction and also the addition of chloride ions increases the palladium uptake. Column studies were performed using 4 and 8% PVP resins in 2 and 4 M nitric acid concentrations. The loaded palladium could be eluted efficiently with acidic thiourea solution.     

Preparation of metal ions impregnated polystyrene resins for adsorption of antibiotics contaminants in aquatic environment

In this study, the strong‐acid polystyrene resin D001 was modified by impregnation with metal ions Fe³⁺, Cu²⁺, and Zn²⁺ to prepare new kinds of sorbents. The modified D001 was characterized by N₂ sorption–desorption isotherms, X‐ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The sorption performance of the metal modified resins for removal of antibiotics tetracycline (TC) and doxycycline (DC) from aquatic environment was investigated and excellent sorption capability with more than 98% removal ratio was observed for these resins after modification. Although these modified resins also presented pH‐dependent sorption, they showed much better flexibility with pH fluctuation than those of the unmodified original D001, and extremely strong sorption capability was exhibited in a wide range of pH 2–8 for both TC and DC. Pseudo‐second‐order kinetic equation described the sorption process more reasonably than pseudo‐first‐order equation. Langmuir isotherm model provided the best match to the equilibrium data with monolayer maximum sorption capacity of 417–625 mg g^?1 under 288–318 K. The sorption capacity decreased with the increase of ionic strength of NaCl. The main sorption mechanism was proposed to be surface complexation, cation bridge interaction and electrostatic attraction/competition between antibiotics and metal modified resins. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41803.     

Photo‐crosslinking of poly[ethene‐stat‐(methacrylic acid)] functionalised with maleimide side groups

BACKGROUND: Photo‐crosslinkable polymers are well known and commercially applied as photoresists. But so far they have not been applied as membrane materials for separation processes. They would offer certain advantages in membrane fabrication over conventional crosslinked polymer materials. Therefore, in this work, a poly[ethene‐stat‐(methacrylic acid)] (PEMAA) which is a potential membrane polymer for different separation problems was functionalised with photo‐crosslinkable maleimide side groups. RESULTS: It has been shown that PEMAA can be used as basic polymer material and a conversion with 3‐hydroxypropylmaleimide is possible in order to obtain a photo‐crosslinkable polymer. Investigation of the crosslinking mechanism was performed using stationary infrared and UV‐visible spectroscopy as well as nanosecond transient spectroscopy absorption measurements of a rotating film. Intense transient absorption of the maleimide‐esterified PEMAA occurs at 250 nm in the film pointing to maleimide anion formation and crosslinking via an ionic dimerisation mechanism. CONCLUSION: It is found that crosslinking reactions can be observed spectroscopically in situ using a maleimide‐functionalised PEMAA. Furthermore, experiments can be performed in the liquid phase (polymer in solution) as well as in the solid phase (polymer film) using a rotating polymer film sample. Maleimide anion formation and crosslinking via an ionic dimerisation mechanism can be investigated by variation of the polymer structure as well as the structure of the maleimide side groups. Copyright © 2009 Society of Chemical Industry     

Ammonium Removal from Aqueous Solutions Using Sulfonated Polystyrene Grafted Silica Gel Sorbent

Abstract

A novel non‐swelling sulfonated polystyrene grafted silica gel sorbent was synthesized for use in ammonium removal from aqueous solutions. The ammonium sorption equilibrium isotherm was determined at 298 K by batch experiments, and the effects of flow rate and initial solution pH on the sorption were measured by breakthrough experiments in a laboratory scale fixed bed column. The equilibrium data were fitted to the Langmuir, Freundlich, Langmuir‐Freundlich, and Toth isotherm models. The breakthrough data were fitted to a dynamic isothermal mathematical model with an axial dispersion term to obtain the effective diffusion coefficient. The sorption rate of the sulfonated polystyrene grafted silica gel is higher than that of ion‐exchange resins, which enables shorter cycle times in column processes for the grafted silica gel.