Nanomaterial Synthesis in Ionic Liquids and Their Use on the Photocatalytic Degradation of Emerging Pollutants

The unique properties of ionic liquids make them suitable candidates to prepare nanoscale materials. A simple method that uses exclusively a corresponding bulk material and an ionic liquid—in this case, [P6,6,6,14]Cl—was used to prepare AgCl nanoparticles and AgCl@Fe3O4 or TiO2@Fe3O4 magnetic nanocomposites. The prepared nanomaterials were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet–visible spectroscopy, and X-ray photoelectron spectroscopy. The photodegradation of atenolol as a model pharmaceutical pollutant in wastewater was investigated under ultraviolet–visible light irradiation using the different synthesized nanocatalysts. In the presence of 0.75 g·L−1 AgCl nanoparticles, a practically complete degradation of 10 ppm of atenolol was obtained after 30 min, following pseudo-first-order reaction kinetics. The effect of different variables (concentrations, pH, oxidant agents, etc.) was analyzed. The recyclability of the nanocatalyst was tested and found to be successful. A degradation mechanism was also proposed. In order to improve the recovery stage of the nanocatalyst, the use of magnetic nanocomposites is proposed. Under the same experimental conditions, a slightly lower and slower degradation was achieved with an easier separation. The main conclusions of the paper are the suitability of the use of ionic liquids to prepare different nanocatalysts and the effectiveness of these at degrading an emerging pollutant in wastewater treatmentThis research was funded by Xunta de Galicia through grant numbers ED431B 2020/21, ED431B 2020/21 and ED431C2017/36, the Spanish Agencia Estatal de Investigación (ref. CTM2017-84763-C3-R-2), and FEDER/ERDF funds (European Regional Development Fund)S

Phase Equilibria of 1-hexyl-3-methylimidazolium acetate with water and oil

Ionic liquids have increased the possibilities of Enhanced Oil Recovery (EOR) with surfactants. However, results obtained with only one of these salts as surfactant are not particularly promising. Best results are obtained with blends of these salts or blends with traditional surfactants. This work aims to break new ground regarding the role of ionic liquids in this application. Many traditional surfactants in EOR fail because they are not sufficiently soluble at optimal salinity in water. The possibilities of design of ionic liquids must also be considered to use them as co-surfactants in optimal formulations for oil recovery. In this work, the phase behaviour of the ionic liquid 1-hexyl-3-methylimidazolium acetate with water and different model oils (n-octane, cyclohexane and toluene) was determined at 298.15 K and 323.15 K. The complete miscibility of the ionic liquid with water and its low miscibility with the different oils, point to the use of 1-hexyl-3-methylimidazolium acetate as co-surfactant with surfactants with high oil solubilising capacityThe authors acknowledge the Ministry of Economy and Competitiveness (Spain) for financial support throughout project CTQ2015-68496-P (including European Regional Development Fund advanced funding)S

Ionic liquids for low-tension oil recovery processes: Phase behavior tests

This is the accepted manuscript of the following article: Rodriguez-Escontrela, I., Puerto, M., Miller, C., & Soto, A. (2017). Ionic liquids for low-tension oil recovery processes: Phase behavior tests. Journal Of Colloid And Interface Science, 504, 404-416. doi: 10.1016/j.jcis.2017.05.102Chemical flooding with surfactants for reducing oil-brine interfacial tensions (IFTs) to mobilize residual oil trapped by capillary forces has a great potential for Enhanced Oil Recovery (EOR). Surface-active ionic liquids (SAILs) constitute a class of surfactants that has recently been proposed for this application. For the first time, SAILs or their blends with an anionic surfactant are studied by determining equilibrium phase behavior for systems of about unit water-oil ratio at various temperatures. The test fluids were model alkane and aromatic oils, NaCl brine, and synthetic hard seawater (SW). Patterns of microemulsions observed are those of classical phase behavior (Winsor I-III-II transition) known to correlate with low IFTs. The two anionic room-temperature SAILs tested were made from common anionic surfactants by substituting imidazolium or phosphonium cations for sodium. These two anionic and two cationic SAILs were found to have little potential for EOR when tested individually. Thus, also tested were blends of an anionic internal olefin sulfonate (IOS) surfactant with one of the anionic SAILs and both cationic SAILs. Most promising for EOR was the anionic/cationic surfactant blend of IOS with [C12mim]Br in SW. A low equilibrium IFT of 2 10 3 mN/m was measured between n-octane and an aqueous solution having the optimal blend ratio for this system at 25 CA. Soto acknowledges the Ministry of Economy and Competitiveness (Spain) for financial support throughout project CTQ2015-68496-P (including European Regional Development Fund advanced funding)S

Liquid systems Based on Tetra(n-butyl)phosphonium Acetate for the Non-dissolving Pretreatment of a Microcrystalline Cellulose (Avicel PH-101)

A non-dissolving pretreatment consisting in the direct contact of cellulose and the ionic liquid tetra(n-butyl)phosphonium acetate, or its fluid mixtures with other phosphonium ionic liquids or with molecular liquids such as ethanol or DMSO, causes a reduction in the crystallinity of the popular microcrystalline cellulose-type Avicel PH-101 under mild conditions. At the same time, the degree of polymerization and the thermal stability of the pretreated Avicel remain essentially unaltered with respect to the untreated Avicel. The diminution of the crystallinity has been related to the increase of the reactivity of the pretreated Avicel samples via analysis of the kinetics of their enzymatic hydrolysis. For selected samples, this improved reactivity has been confirmed through their effective carboxymethylation under a simplified and milder reaction procedureThis work was supported by Xunta de Galicia through project ED431B 2020/021, co-funded by the European Regional Development Fund. A.V.P. thanks the Spanish Ministry of Science and Innovation, the Spanish Research State Agency, and the European Social Fund for a “Ramón y Cajal” contract (RYC-2017-22849)S

Design and performance analysis of a formulation based on SDBS and ionic liquid for EOR in carbonate reservoirs

A large proportion of extant crude oil is found in carbonate reservoirs worldwide. Alkylbenzene sulfonates are inexpensive anionic surfactants but they cannot be used in these reservoirs due to their incompatibility with divalent ions and high adsorption on the rocks. This paper proposes the solution to that problem by blending this kind of surfactant with surface-active ionic liquids. Namely, a formulation containing sodium dodecylbenzenesulfonate (SDBS) and cocosalkylpentaethoximethylammonium methylsulfate ([C1EG][MeSO4]) was designed for the application. Two optimal blends, at 40/60 and 73.7/26.3 SDBS/[C1EG][MeSO4] ratios, were found in synthetic seawater via equilibria and interfacial tension (IFT) studies. Core-flooding tests were carried out to check the performance of both blends. The first blend ratio (40 wt% SDBS) was selected to define an optimal formulation (1 wt% blend in synthetic seawater at 298.15 K) due to its better injectability, higher reduction of the IFT, lower adsorption, and better oil recovery. Attained tertiary oil recovery (18% of the original oil in place), with low blend adsorption (0.37 mgblend/grock), shows the promising performance of the solution. The main mechanism associated with improved oil recovery is IFT reduction. This work offers a significant advance in the application of natural petroleum sulfonates in carbonate reservoirsThe authors acknowledge the Ministry of Science and Innovation and State Research Agency for financial support throughout project PGC2018-097342-B-I00, including European Regional Development Fund). A. Somoza also acknowledges predoctoral financial support (grant ref. PRE2019-089101). We would also like to thank SNF Floerger for supplying polymer samples, Repsol (A Coruña) for providing the crude oil used for the experiments, and L. Membrado (Separation and Detection Group, Instituto Carboquímico de Zaragoza) for the realization of the SARA analysis of the crude oilS

Improved concentration of citrus essential oil by solvent extraction with acetate ionic liquids

© 2014. This is the accepted manuscript of the following article: Lago, S., Rodríguez, H., Arce, A., & Soto, A. (2014). Improved concentration of citrus essential oil by solvent extraction with acetate ionic liquids. Fluid Phase Equilibria, 361, 37-44. doi: 10.1016/j.fluid.2013.10.036Citrus essential oils have numerous applications in multiple sectors, including food, drink and personal care industries. Although mainly constituted by terpenes, the appealing characteristics of citrus essential oils are due to oxyterpenes and other derived oxygenated compounds. In fact, the presence of terpenes in the essential oil may lead to instability or loss of quality. Therefore, concentration of the oil in its oxyterpene compounds by removal of terpenes is desirable. The techniques currently in use for deterpenation of essential oils present a series of issues. In the search for better deterpenation processes, here the use of ionic liquids as solvents in liquid-liquid extraction is explored. In particular, the ionic liquids 1-ethyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium acetate are investigated for their extraction of oxyterpene from a modelled citrus essential oil composed of limonene (terpene) and linalool (oxyterpene). The choice of the ionic liquids, in addition to other complementary characteristics, was based on a rationale of potential interactions that can be created preferentially with the linalool. The results show a great performance of these acetate-based ionic liquids, as compared to any other ionic or molecular solvent tested to date, for the concentration in oxyterpenes of the citrus essential oilThe authors acknowledge the Ministry of Economy and Competitiveness of Spain for financial support through project CQT2012-33359 (including European Regional Development Fund advanced funding), and through the Ramón y Cajal programme (H.R.)S

Design and Characterization of Naphthalene Ionic Liquids

Surfactants have a great number of applications. Among these chemicals, petroleum sulfonates have been widely used due to their effectiveness in reducing interfacial tension. This is the case of sodium octylnaphthalene sulfonate which is a solid with a very low solubility in water. To overcome these drawbacks, this work aimed to synthesize new surface active ionic liquids based on a naphthalene sulfonate anion and traditional cations of these salts (imidazolium, pyrrolidinium, and pyridinium). The new chemicals showed high thermal stability, ionic liquid nature, and a stronger surfactant character than the original naphthalene. Moreover, they were found to be water soluble which greatly facilitates their application in the form of aqueous formulations. 1-Hexyl-3-methylimidazolium 4-(n-octyl)naphthalene-1-sulfonate showed the best capacity to reduce water-air and water-oil interfacial tensionThe authors acknowledge the Spanish Ministry of Science and Innovation, State Research Agency and European Regional Development Fund for financial support throughout project PGC2018-097342-B-I00, the Xunta de Galicia through the project EDA431D 2017/06S

Building an IP-based community wireless mesh network: Assessment

Wireless mesh networks are experiencing rapid progress and inspiring numerous applica tions in different scenarios, due to features such as autoconfiguration, self healing, connec tivity coverage extension and support for dynamic topologies. These particular characteristics make wireless mesh networks an appropriate architectural basis for the design of easy to deploy community or neighbourhood networks. One of the main chal lenges in building a community network using mesh networks is the minimisation of user intervention in the IP address configuration of the network nodes. In this paper we first consider the process of building an IP based mesh network using typical residential rou ters, exploring the options for the configuration of their wireless interfaces. Then we focus on IP address autoconfiguration, identifying the specific requirements for community mesh networks and analysing the applicability of existing solutions. As a result of that analysis, we select PACMAN, an efficient distributed address autoconfiguration mechanism origi nally designed for ad hoc networks, and we perform an experimental study using off the shelf routers and assuming worst case scenarios analysing its behaviour as an IP address autoconfiguration mechanism for community wireless mesh networks. The results of the conducted assessment show that PACMAN meets all the identified requirements of the community scenario.European Community´s Seventh Framework ProgramPublicad

Ionic Liquids derived from proline: application as surfactants

This is the peer reviewed version of the following article: V. Fernández-Stefanuto, R. Corchero, I. Rodríguez-Escontrela, A. Soto, E. Tojo, ChemPhysChem 2018, 19, 2885, which has been published in final form at https://doi.org/10.1002/cphc.201800735. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsIonic liquids derived from prolinium esters, previously described as fully green and stable, were found to decompose in the presence of water by ester hydrolysis. To avoid this problem, a new family of these biodegradable salts incorporating an alcohol instead of the ester group is proposed. From this family, two novel ionic liquids that incorporate the prolinolium cation [HOPro] and the [DS] or [DBS] anion were selected (DS=dodecylsulfate; DBS=dodecylbenzenesulfonate). Both salts are liquid at room temperature, a property not usually found in ionic surfactants, and are also chemically and thermally stable. Moreover, they are more effective in reducing the surface tension of water than the corresponding traditional surfactants in the form of sodium salts, being useful for applications related to their aggregation capacity. They were tested for surfactant enhanced oil recovery and an optimal formulation for reservoirs at high salinity and temperature, able to produce ultra‐low interfacial tension, was found with [HOPro][DBS]A.S. acknowledges the Ministry of Economy and Competitiveness (Spain) for financial support throughout project CTQ2015‐68496‐P (including European Regional Development Fund advanced funding). E.T. thanks the Xunta de Galicia (ED431D 2017/06) for their financial supportS

Recovery of dialkylimidazolium-based ionic liquids from their mixtures with acetone or water by flash distillation

In a number of applications for which novel processes based on ionic liquids have been proposed, the recovery of the ionic liquid from its mixture with a molecular solvent is a step of critical importance for the viability of the process. In this work, feasibility and conditions for such recovery by simple flash vapourisation have been explored for the particular case of three dialkylimidazolium-based ionic liquids (namely 1-ethyl-3-methylimidazolium thiocyanate ([C2mim][SCN]), 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), and 1-butyl-3-methylimidazolium acetate ([C4mim][OAc])) and either acetone or water as representative molecular solvents of industrial relevance. The isobaric vapour-liquid equilibria of the binary systems acetone + ([C2mim][SCN] or [C4mim][OAc]) and water + ([C2mim][OAc] or [C4mim][OAc]) have been determined at three different pressures (101.32, 50.00, and 30.00 or 25.00 kPa), and the data have been suitably correlated by means of the NRTL thermodynamic model. These correlations have been used in the software Aspen Plus for the development of reliable simulations of a flash unit to perform the desired separations. The results indicate the difficulty in getting the ionic liquids recovered with high purity, even if operating the flash at a pressure as low as 5 kPa and at temperatures close to the range where the thermal stability of the ionic liquids starts to get compromisedThe authors acknowledge Xunta de Galicia for support through project ED431B 2020/021. M.K.W. is grateful to the Erasmus + programme of the European Union for the award of a mobility traineeshipS