Modelling the sorption of water–ethanol mixtures in cross-linked ionic and neutral polymers (original) (raw)
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Industrial & Engineering Chemistry Research, 1999
Experimental data for the distribution of water-ethanol mixtures between a solid phase and a liquid phase at 298 K are reported. The solid phases studied were gel-type sulfonated poly-(styrene-co-divinylbenzene) resins of different degrees of cross-linking (4-8% DVB) and carrying different counterions (Na + , Ca 2+ , and La 3+ ). The shear moduli of the resin beads were also measured to characterize their elastic properties. All resins absorb water selectively, and the selectivity increases with increasing cross-link density. The low selectivity of the less densely cross-linked resins is shown to be mainly due to the mutual interaction of the solvents in the resin phase resulting in a pronounced maximum in the ethanol sorption isotherms. The influence of the counterion on the selectivity is more complex. At high water contents, the water selectivity of the Na + resin is higher than that of the Ca 2+ and La 3+ resins, whereas the selectivities are approximately equal at low water contents. The elastic properties of the resin beads remain unchanged from pure water to water mole fractions of around 0.4, where a sharp rise in the shear modulus occurs. The data are analyzed by means of a model based on the UNIQUAC equation and the affine network theory of elasticity. The effect of cross-link density on the selectivity and solvent content of the resins can be explained satisfactorily with the model. However, the calculated and experimental sorption isotherms for the La 3+ resins deviate appreciably at low external water contents. The discrepancies are discussed on the basis of the elastic properties of the resins and the specific solvation interactions.
An Assessment on the Interaction of a Hydrophilic Ionic Liquid with Different Sorbents
Industrial & Engineering Chemistry Research, 2009
Ionic liquids have received an upsurge in interest as green solvents, primarily as replacements for conventional media in chemical processes. This growing interest may soon lead to their presence in the environment. To evaluate the environmental fate of ionic liquids, their sorption onto different media is an essential parameter. This study presents an experimental verification of the sorption of 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) onto different sorption media. The examined sorption media included two activated carbons (SPS-200 and SPC-100), an ion-exchange resin (IER), a fermentation waste (Corynebacterium glutamicum), and a dried activated sludge. Through HPLC and MS/MS analysis, [BMIM][Cl] was found to be stable only in the pH range 3 to 11. The experimental results reveal that removal of [BMIM][Cl] was only possible using IER and the two forms of activated carbon. The equilibrium solution pH was found to have no significant effect on the sorption ability of IER, whereas, both forms of activated carbon exhibited high sorption under strong alkaline conditions. No significant sorption of [BMIM] was observed with both C. glutamicum and the activated sludge. According to the Langmuir model, the IER can sorb as much as 179.4 mg [BMIM]/g, whereas those of SPS-200 and SPC-100 were 20.6 and 19.6 mg [BMIM]/g, respectively. The sorption kinetics was found to be rapid, with only 15 and 60 min required to attain equilibrium for IER and the two forms of activated carbon, respectively. Only IER exhibited significant sorption ability toward chloride ions which are an anionic part of the IL.
Polymers, 2020
A new type of hybrid polymeric-based film containing 1-(1,3-diethoxy-1,3-dioxopropan-2-ylo)-3-methylimidazolium bromide (RIL1_Br) and 1-(2-etoxy-2-oxoethyl)-3-methylimidazolium bromide (RIL2_Br) reactive ionic liquids was elaborated. Poly(vinyl alcohol) (PVA)-based films with 9–33 wt % of RILs were subsequently characterized using Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA) and TGA-FTIR. PVA-RIL films were also studied in tensile tests, contact angle and sorption measurements. RIL incorporation enhanced thermal and mechanical stability of PVA membranes due to the hydrogen bonds between RILs and polymer chains. Membrane swelling behavior in water (H2O), ethanol (EtOH), and propan-2-ol (IPA) and the kinetics of water sorption process revealed that PVA-RILs membranes possess the highest affinity towards water. It was pointed out that both the RIL...
Journal of Molecular Liquids, 2019
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Evaluation of Crosslinking on the Water Sorption Properties of Poly(Vinyl) Alcohol
2015
Poly (vinyl) alcohol has the ability to sorb water depending on the degree of hydrolysis and its molecular weight. Thus, a low molecular weight PVA is expected to have more water solubility and more water sorbing properties. These properties could also be affected by the crosslinking conditions employed. In this study, PVA crosslinked with glutaraldehyde at the 1:10 and 1:5 PVA to GA ratios for 1 and 6h at 70 °C and a pH of 5.5 and 6.5 was conducted followed by precipitation and washing with acetone and further drying. The resulting films were exposed to water activities from 0 to 0.9 and submitted to swelling and contact angle studies. All materials exhibited a type III isotherm shape. Crosslinking induced the formation of a more porous material with a low sorption capacity as compared to the parent material. Further, the low water uptake diffused in those films explained their low water swelling capacity.
Sorption studies on ion exchange resins. 1. Sorption of strong acids on weak base resins
Industrial & Engineering Chemistry Research, 1992
Sorption equilibria and batch dynamics of weak acids (formic acid and monochloroacetic acid) on weak base ion exchange resins, in free base form, are studied. The reversible sorption model based on double layer theory, developed in part 1 of these studies, is extended to take into account undissociated acid species. The model fits the experimental dynamics satisfactorily over the entire range of resin conversion. Values of effective ionic pore diffusion coefficient, regressed from the observed experimental dynamics, have been satisfactorily correlated on the basis of the model. These studies reveal that the contributions of both the ionic and the undissociated molecular species are important in determining the total diffusive flux of the acid in the pores of the resin. .. Cliffs, Nj, 1978. Process Technol. 1981.2, 1. I Wadekar, V. V.; Sharma, M. M. Dissociation extraction. J. Sep.
Sorption studies on ion exchange resins. 2. Sorption of weak acids on weak base resins
Industrial & Engineering Chemistry Research, 1992
Sorption equilibria and batch dynamics of weak acids (formic acid and monochloroacetic acid) on weak base ion exchange resins, in free base form, are studied. The reversible sorption model based on double layer theory, developed in part 1 of these studies, is extended to take into account undissociated acid species. The model fits the experimental dynamics satisfactorily over the entire range of resin conversion. Values of effective ionic pore diffusion coefficient, regressed from the observed experimental dynamics, have been satisfactorily correlated on the basis of the model. These studies reveal that the contributions of both the ionic and the undissociated molecular species are important in determining the total diffusive flux of the acid in the pores of the resin. .. Cliffs, Nj, 1978. Process Technol. 1981.2, 1. I Wadekar, V. V.; Sharma, M. M. Dissociation extraction. J. Sep.
In the present investigation the sorption-desorption kinetics of 75 vol % ethanol/ water solution by dimethacrylate-based dental resins and resin composites was studied in detail. The resins examined were made by light-curing of bisphenol A glycol dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), bisphenol A ethoxylated dimethacrylate (Bis-EMA), and mixtures of these monomers. The resin composites were prepared from two commercial light-cured restorative materials (Z100 MP and Filtek Z250), the resin matrix of which is based on copolymers of the above-mentioned monomers. Ethanol/water sorption/desorption was examined in both equilibrium and dynamic conditions in two adjacent sorption-desorption cycles. For all the materials studied, it was found that the amount of ethanol/water sorbed or desorbed was always larger than the corresponding one reported in literature in case of water immersion. It was also observed that the chemical structure of the monomers used for the preparation of the resins directly affects the amount of solvent sorbed or desorbed, as well as sorption kinetics, while desorption rate was nearly unaffected. In the case of composites studied, it seems that the sorption/desorption process is not influenced much by the presence of filler. Furthermore, diffusion coefficients calculated for the resins were larger than those of the composites and were always higher during desorption than during sorption. Finally, an interesting finding concerning the rate of ethanol/water sorption was that all resins and composites followed Fickian diffusion kinetics during almost the whole sorption curve; however, during desorption the experimental data were overestimated by the theoretical model. Instead, it was found that a dual diffusionrelaxation model was able to accurately predict experimental data during the whole desorption curve. Kinetic relaxation parameters, together with diffusion coefficients, are reported for all resins and composites. ' Scheme 1. Chemical structure of the used dimethacrylate monomers.
Liquid–liquid equilibria in ternary systems of linear and cross-linked water-soluble polymers
Fluid Phase Equilibria, 2002
In this study, ternary liquid–liquid equilibrium data of structurally similar linear and cross-linked polymers have been measured in order to elucidate the significance of mixing and elastic effects in sorption of binary liquid mixtures by cross-linked polymers. Dextran, sodium poly(styrene sulfonate), and sodium poly(acrylate) were used as the linear analogues for Sephadex gels and for strong and weak cation exchange resins. Cloud-point and co-existence curves were measured in water/ethanol and water/2-propanol mixtures at 283–343K and the results were correlated by using a generalized Flory–Huggins model. The mixing parameters of the linear polymers were used to simulate the sorption data in the cross-linked materials and the effect of cross-links was accounted for by a non-ideal elastic model. Good agreement between the simulated and experimental values is obtained, when the chemical heterogeneity and the incomplete functionalization of the cross-linked materials are taken into account. The influence of temperature on the sorption equilibria in cross-linked polymers is also discussed on the basis of the temperature dependence of the cloud-point data.
Solvent sorption in a polymer–solvent system – Importance of swelling and heat effects
Polymer, 2006
Sorption experiments are often conducted in gravimetric sorption columns where several deviations from ideal conditions could potentially occur. For example, heat effects due to solvent sorption, errors introduced due to concentration dependent diffusion coefficients and swelling are unavoidable. In this study, we develop a model to study the importance of the combination of these effects in obtaining diffusion coefficients from sorption experiments. The model is used to explore a wide range of operating conditions and physical parameters.