Composition and structural effects on the adsorption of ionic liquids onto activated carbon (original) (raw)
Related papers
Adsorption of ionic liquids from aqueous effluents by activated carbon
Carbon, 2009
The separation of imidazolium-based ionic liquids (ILs) from aqueous solution by adsorption has been investigated using a commercial activated carbon (AC) as adsorbent. Equilibrium experiments were carried out for obtaining the adsorption isotherms of ILs on AC at different temperatures. The influence of both cation and anion was analyzed by studying 17 different ILs. The role of the surface chemistry of the adsorbent was also examined using ACs modified by oxidative and thermal treatments. The incorporation of IL on the AC surface was studied by N 2 adsorption-desorption measurements and elemental analysis. In addition to this, a COSMO-RS computational approach was developed to estimate molecular and thermodynamic properties of the solvent-adsorbate-adsorbent system, which allowed us to analyze the adsorption mechanism from a molecular point of view. The results of this work indicate that the adsorption with AC is an affordable environmental application to remove hydrophobic ILs from water streams, proposing the use of acetone for adsorbent regeneration. It has also been demonstrated that the adsorption of refractory hydrophilic ILs can be improved by modifying the amount and nature of oxygen groups on the AC surface, particularly by including hydroxyl groups to promote hydrogen-bonding interactions with the basic groups of hydrophilic ILs.
Adsorption of ionic liquids onto activated carbons: Effect of pH and temperature
Microporous and Mesoporous Materials, 2012
In this study, the uptake of hydrophobic bromide-based ionic liquids (ILs) (imidazolium, pyrrolidinium, and pyridinium) from aqueous solutions onto granulated and fabric-based microporous activated carbons (ACs). Surface characterization study shows that both ACs have basic pHpzc, like 8.7 for granulated AC and 8.0 for fabric AC. Granulated AC have ten times higher phenolic groups 0.2 meq g −1 compared to fabric AC which is 0.03 meq g −1. The kinetics of adsorption was remarkably slower for ILs on granulated/fabric AC than milled one. We also studied the effect of AC size on the rate of adsorption in the operating conditions. In order to improve the adsorption kinetics of ILs with ACs, different phenomenological and empirical kinetic models like as pseudo-first order, Boyd model, pseudo-second-order diffusion model and Elovich were applied on the kinetic experimental data. The analysis of kinetic specified that the adsorption mechanism of ILs onto ACs is controlled mainly by the mass transfer through the pores of ACs. So, the selection of appropriate adsorbent particle size of AC plays a main role for the development of viable IL adsorption.
Fixed-bed adsorption of ionic liquids onto activated carbon from aqueous phase
Journal of Environmental Chemical Engineering, 2017
The separation of ILs from water by fixed-bed adsorption with AC was evaluated. Particle size and superficial liquid velocity are key factor regarding the efficiency. The nature of IL plays a key role in the thermodynamics and kinetics of adsorption. Fixed-bed adsorption with AC was found a feasible for hydrophobic ILs removal.
2012
APPENDIX 4. Adsorption of Cl-VOCs on SILP materials in fix bed reactor . . . . El apartado de resultados y discusión se ha organizado en forma de un compendio de contribuciones científicas publicadas en revistas internacionales como resultado del trabajo de investigación realizado durante el desarrollo de la presente Tesis Doctoral. Estos resultados se pueden clasificar en dos grandes bloques: el primero de ellos se centra en el tratamiento de LIs en fase acuosa y el segundo en la preparación, caracterización y aplicación de materiales avanzados basados en LIs sobre una matriz sólida, principalmente CAs. De este modo, el primer bloque de resultados consta de 3 publicaciones, en las que se propone una guía para la retención de LIs de corrientes acuosas, basada en la adsorción sobre CAs comerciales. El Artículo I presenta las isotermas de adsorción de 17 LIs sobre un CA comercial en fase acuosa. Se ha utilizado el método químico-cuántico COSMO-RS para describir las interacciones intermoleculares existentes en estos sistemas trifásicos (LI-agua-CA). También se muestra la caracterización de los sistemas mixtos (LI/CA). Por último, se propone la regeneración del CA, junto con la recuperación del LI, utilizando acetona como disolvente. El Artículo II extiende el espectro de LIs estudiados a un total de 27, así como el número de materiales adsorbentes, que incluye 12, con propiedades estructurales y químicas diversas. Esta variedad de LIs permite evaluar la influencia tanto del anión como del catión, así como del efecto de la porosidad y la naturaleza química del adsorbente en el proceso de adsorción. Además, gracias al estudio de las interacciones intermoleculares mediante COSMO-RS, se proponen funcionalizaciones optimizadas del CA que favorecen la adsorción de los LIs hidrofílicos, a priori refractarios a la adsorción sobre los CAs comerciales ensayados. El Artículo III describe un estudio cinético de la adsorción de un LI de referencia bajo diferentes condiciones de operación, como temperatura, tamaño de partícula, agitación y concentración inicial de LI, así como el tipo de CA utilizado. El estudio cinético permite establecer los mecanismos que determinan el proceso de adsorción y evaluar cómo afectan las condiciones de operación a las etapas controlantes. La evaluación conjunta de las 3 contribuciones sirve de guía para definir las características del material adsorbente y las condiciones de operación que favorecen la adsorción tanto en términos termodinámicos como cinéticos. ENIL systems open up new application fields which may include separation processes, catalytic or electrochemical. As a further contribution of this Doctoral Thesis a systematic characterization of these novel materials based on IL and AC was proposed (both SILP as ENIL). In this sense, it was established that elemental analysis (EA) allows to immediately and accurately quantify the incorporation of imidazolium-based IL on the support, a technique that has been usefully proved in a wide variety of solids. Meanwhile, the nitrogen adsorption/desorption and mercury porosimetry to assess the distribution of IL in the porous structure on the support, having observed a hierarchical IL incorporation on the solid. Scanning electron microscopy (SEM) and transmission (TEM) enable to observe the placing of IL on the solid matrix, and also to assess the morphology of these materials, showing that the outer surface is covered by high amounts of IL. Energy-dispersive X-ray spectroscopy (EDX) detects certain elements present in advanced material, such as P, F or B. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) assess the thermal stability of these materials mixed, concluding that its stability and the IL decomposition mechanism are influenced by the chemistry surface of the solid support. Another objective of this work is the use of molecular simulation tools to support the experimental research lines, which are of particular interest in the field of ILs, due to the large number of possible ion combinations. Molecular simulation refers to a set of useful computational methods which describe the matter behavior from information from its molecules. Among the available models, the COSMO-RS method has great potential for application to the development of new processes based on ILs. COSMO-RS predict thermodynamic properties from quantum-chemical calculations based on simple molecular models without previous experimental data. Its implementation has yielded valuable information regarding different parts of this Doctoral Thesis, as predicting properties of ILs (density, viscosity, molecular volume) and their mixtures (G-L equilibrium data, L-L, L-S and G-S) for validation and experimental justifications for their behavior. On the other hand, allows the design of IL or AC with suitable properties for the retention of gaseous pollutants, by calculating the equilibrium constants, key information for G-L separation operations or G-S (Henry's constant and partition coefficients). This simulation provides an efficient procedure for selecting the anion-cation ion pair for optimal properties of IL, thus avoiding lengthy and expensive experimental studies and to evaluate the effect of the surface oxygen groups in ACs SUMMARY XXII for a suitable functionalization of face for further application as adsorbent materials. Moreover, the intermolecular interactions understanding based on excess enthalpies of binary mixtures including IL is show as useful for the design of systems in order to gaseous ammonia separation based on ILs or adsorption of ILs from aqueous phase using AC with different chemical nature.
Processes
The serious environmental issues associated with CO2 emissions have triggered the search for energy efficient processes and CO2 capture technologies to control the amount of gas released into the atmosphere. One of the suitable techniques is CO2 adsorption using functionalized sorbents. In this study, a functionalized activated carbon (AC) material was developed via the wet impregnation technique. The AC was synthesized from a rubber seed shell (RSS) precursor using chemical activation and was later impregnated with different ratios of [bmpy][Tf2N] ionic liquid (IL). The AC was successfully functionalized with IL as confirmed by FTIR and Raman spectroscopy analyses. Incorporation of IL resulted in a reduction in the surface area and total pore volume of the parent adsorbent. Bare AC showed the largest SBET value of 683 m2/g, while AC functionalized with the maximum amount of IL showed 14 m2/g. A comparative analysis of CO2 adsorption data revealed that CO2 adsorption performance of ...
Journal of Environmental Chemical Engineering, 2019
HIGHLIGHTS Activated carbon supported functionalised amine ionic liquids enhances the CO2 sorption Activated carbon supported mono-functionalised amine ionic liquids are higher than multi-functionalised amine in CO2 sorption CO2 sorption increases with the increase of alkyl chain length in protic ionic liquids Activated carbon supported ionic liquids follow the Freundlich isotherm model
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.
Activated Carbon Supported Amine Functionalized Ionic Liquids for CO2 Sorption
Journal of Physics: Conference Series, 2018
Ionic liquids (ILs) have been proven to produce promising results in CO2 capture. However, ILs suffer the problem of having high viscosities which limit the application. Impregnation of ILs into porous solid support may be an alternative to overcome this problem. In this study, the wet impregnation method was used and this was confirmed by surface area, pore volume and pore size before and after impregnation. Activated carbon impregnated with 10wt% of [hmim][NTf2], [vbtma][gly] and poly[vbtma][gly] were prepared to study the CO2 sorption. The results showed that activated carbon impregnated with [vbtma][gly] gives higher CO2 sorption with 19.91 mmol/g at 20 bar. Therefore, a series of activated carbon impregnated with 10wt%, 20wt% and 30wt% of [vbtma][gly] were prepared to study the optimum composition of [vbtma][gly] for CO2 sorption. The CO2 sorption studied showed the optimization occurred at 20wt% of poly[vbtma][gly] and CO2 uptake increased with pressure increased.