Héctor Rodríguez

• PhD
• University of Santiago de Compostela

Lignin is a very attractive and abundant biopolymer with the potential to be a biorenewable source of a large number of added-value organic chemicals. The current state-of-the-art methods fail to provide an efficient valorization of lignin in this regard without the involvement of harsh conditions and auxiliary substances that compromise the overal...

The growing need to expand the use of renewable energy sources in a sustainable manner, providing greater energy supply security and reducing the environmental impacts associated with fossil fuels, finds in the agricultural by-product bioethanol an economically viable alternative with significant expansion potential. In this regard, a dramatic boos...

Industrial fish and aquaculture processing leads to the generation of a huge quantity of by-products, whose accumulation and mismanagement involve serious environmental consequences as well as high economic losses. Taking advantage of these residues as a source of added-value compounds must be a priority in a circular economy. This work is a prelim...

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 m...

Several physical properties and the isobaric vapour-liquid equilibria at 101.32, 50, and 30 kPa were measured for the binary system consisting of acetone and the ionic liquid 1-ethyl-3-methyl-imidazolium acetate. Liquid-liquid equilibrium data were also measured at temperatures from 298.15 up to 328.35 K and atmospheric pressure. An hourglass-shape...

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 vaporisation have been explored for...

Eutectic solvents are currently being proposed as useful chemicals for enhanced oil recovery (EOR). In this work, for the first time, the preparation of eutectics based on surfactants and polymers was proposed for this application. These chemicals can be tailored to offer the most desired properties for oil recovery: water/oil interfacial tension r...

The solid-liquid equilibria of four binary mixtures consisting of different pairs of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ionic liquids with variable lengths of the alkyl substituent were investigated. For the binary system resulting from the mixing of the ionic liquids with the ethyl and octadecyl substituents, the solid-l...

The absorption and desorption isotherms of CO2 in the ionic liquid tetrabutylphosphonium acetate ([P4 4 4 4][OAc]) were experimentally determined at 343.2 K in the pressure range 0–15 bar. Analysed in a mass basis, the CO2 absorption capacity of [P4 4 4 4][OAc] is particularly competitive among that of phosphonium ionic liquids. A contribution of c...

The pretreatment is a key step in the processing of lignocellulosic biomass for its transformation into chemicals and materials of biorenewable origin. Ionic liquids, with their characteristic set of unique properties, have the potential to be the basis of novel pretreatment processes with higher effectiveness and improved sustainability as compare...

The ionic liquids 1-ethyl-3-methyl-imidazolium acetate ([C2mim][OAc]) and 1-ethyl-3-methylimidazolium thiocyanate ([C2mim][SCN]) have been proposed to improve many processes from the point of view of efficiency and/or sustainability. In a number of those proposals, mixtures of these ionic liquids with alcohols are generated. On the assumption of ea...

The improvement of the reactivity of cellulose by means of an efficient pretreatment method is critical for the optimal valorisation of this biorenewable polymer within a biorefinery context. In this work, a non-dissolving procedure for the pretreatment of cellulose, based on the direct solid-liquid contact of cellulose with an ionic liquid, namely...

Preparing, finding and making the transition from a Bachelor degree level to a successful job in the profession of Chemical Engineering requires not only an investment of time and effort but also prior training in a work placement environment, which allows the development and strengthening of the professional skills of the future graduates. A centr...

The thermal behaviour of mixtures of 1-alkylpyridinium halide salts, comprising either three or four different types of ions, was investigated in order to develop a better understanding of this class of multi-ion systems. A total of six systems was examined, derived from all possible binary combinations of the following four salts: 1-butylpyridiniu...

The ability to dissolve cellulose, by using mixtures of ionic liquids, has been studied and compared with results obtained for the corresponding single ionic liquids. The ionic liquid mixtures tested were a 3:7 mol/mol mixture of 1-ethyl-3-methylimidazolium chloride ([C2mim]Cl) and 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), and the eutecti...

In this work, the non-ideal behavior of ionic liquid (IL) mixtures is analyzed to explore potential synergistic effects on CO2 capture through physical absorption. For this purpose, a preliminary thermodynamic analysis was performed based on the quantum-chemical COSMO-RS method. The Henry's constants of CO2 in more than 400 (reciprocal or not) IL b...

Hydrophobic, long-chain tetraalkylphosphonium acetate salts (ionic liquids) were combined with a dipolar aprotic co-solvent, dimethylsulfoxide (DMSO), and the feasibility of these solvent systems for cellulose dissolution and regeneration was studied. A 60 : 40 w/w mixture of the ionic liquid tetraoctylphosphonium acetate ([P 8888 ][OAc]) and DMSO...

A thermal and physical characterization of the binary mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) with 1-propanol or with 2-propanol was carried out. Thermogravimetric analyses confirmed that the stability of the ionic liquid is not reduced by the presence of the propanols. The density, viscosity, refractive inde...

Pairs of ionic liquids with the chloride or acetate anion as common ion and with largely different cations (namely a 1-alkyl-3-methylimidazolium cation and either methyltrioctylammonium or trihexyl(tetradecyl)phosphonium) were selected to investigate their mutual miscibility. Most of the pairs investigated were found to give rise to biphasic, non-v...

The unique characteristics of ionic liquids (salts which are liquid at or near-ambient temperature) open new horizons in the development of improved processes to carry out the separation of compounds from multicomponent feedstreams or feedstocks. The utilisation of ionic liquids can facilitate improvements in the performance of state-of-the-art tec...

This book discusses capital separation processes of industrial interest and explores the potential for substantial improvement offered by a promising class of substances: ionic liquids. These low melting point salts, with their unique characteristics, have been gaining relevance in the field of separation through a variety of approaches. The chapte...

Ionic liquids are the basis of a promising technology for the dissolution and fractionation of lignocellulosic materials. The use of a miscible organic cosolvent as additive may improve the physical properties of the dissolving fluid, as compared to those of the ionic liquid alone. Alternatively, this organic substance added in larger amounts can a...

The solid–liquid equilibria of five systems consisting of different pairs of pyrrolidinium-based ionic liquids were investigated. For all five tested systems the solid–liquid phase behaviour was found to be of eutectic type, and the eutectic compositions and temperatures were determined. Additional experiments were carried out to determine thermal...

Water-miscible ionic liquids (ILs) may be salted out using kosmotropic salts such as potassium phosphate (K3PO4) to form salt–salt aqueous biphasic systems (ABS). The effect of temperature on these systems has been studied using phase diagrams and it is observed that the degree of binodal shift decreases (requiring lower IL and kosmotropic salt con...

The composition and temperature of three eutectic mixtures were determined at atmospheric pressure in systems resulting from the combination of pairs of ionic liquids where each ionic liquid was constituted by only one type of cation and only one type of anion. In addition, the three pairs investigated had a common ion (either the cation or the ani...

Ionic liquids have attracted great interest recently as the basis of a potential alternative technology for the capture of carbon dioxide. Beyond the inherent tunability of properties of individual ionic liquids, a further strategy in optimising the ionic liquid sorbent for this application is the use of mixtures of 'pure' ionic liquids. Some ionic...

The solubility of standards of the representative biopolymers of lignocellulosic biomass (cellulose, hemicellulose, and lignin) in mixtures of controlled composition of an ionic liquid capable of dissolving biomass (namely 1-ethyl-3-methylimidazolium acetate, [C2mim][OAc]) and a volatile antisolvent (namely ethanol) was explored. On the basis of th...

Abstract Concerns about the pollution associated to the sulfur content of fuels have stimulated the search for new alternative technologies to the classical hydrodesulfurization process. The use of ionic liquids to remove sulfur compounds from hydrocarbons by solvent extraction is the object of ongoing research. Most of the publications in this fro...

Two ionic liqs., 1-ethylpyridinium docusate (IL1) and tri-n-butyl(2-hydroxyethyl)phosphonium docusate (IL2), were designed and synthesized with the explicit intention of imparting a combination of plasticization and antimicrobial efficacy when incorporated into medical grade poly(vinyl chloride)s (PVCs). The glass transition (Tg) of PVC can be redu...

Citrus 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 in...

Ionic liquids are a potential alternative of interest for the replacement of volatile organic compounds in the technologies currently used for the capture of carbon dioxide from gaseous streams. Most studies carried out to date on the absorption of CO2 by ionic liquids focus on imidazolium ionic liquids. Pyridinium ionic liquids can exhibit a simil...

Ionic liquids are the basis of a potential alternative to conventional processes based on aqueous amines currently used for carbon dioxide capture. Mixtures of ionic liquids offer an additional degree of tailoring over the intrinsic tunable properties of “single” ionic liquids, while totally maintaining the ionic liquid character. In this work, two...

Viaxe polo río Ulla descubrindo as pontes, pontellas e pasos que o atravesan desde o seu nacemento ata a súa desembocadura na ría da Arousa.

With a decrease in world oil reserves and a higher demand for petroleum and its derived products, the effective exploitation of oil reservoirs has become increasingly important. Enhanced oil recovery (EOR) assisted by surfactants is an effective method for recovering the oil from reservoirs that have lost their drive after the application of primar...

Ionic liquids are possible alternative solvents for the separation of aromatic and aliphatic hydrocarbons by liquid-liquid extraction. Interfacial tension is an important property to consider in the design of liquid-liquid extraction processes. In this work, the liquid-liquid interfacial tension and the mutual solubility at 25 °C have been measured...

Pharmaceutically active compounds in ionic liquid form immobilized onto mesoporous silica are stable, easily handled solids, with fast and complete release from the carrier material when placed into an aqueous environment. Depending on specific ion-surface interactions, they may also exhibit improved thermal stability when compared to the non-adsor...

Suitable α-cellulose and cellulose II powders for use in the pharmaceutical industry can be derived from maize cob. α-Cellulose was extracted from an agricultural residue (maize cobs) using a non-dissolving method based on inorganic substances. Modification of this α-cellulose was carried out by its dissolution in the ionic liquid 1-butyl-3-methyli...

New polyethylene glycol (PEG)/ionic liquid aqueous biphasic systems (ABS) are presented. Distinct pairs of PEG polymers and ionic liquids can induce phase separation in aqueous media when dissolved at appropriate concentrations. Phase diagrams have been determined for a large array of systems at 298, 308 and 323 K. A comparison of the binodal curve...

Just add liquid and stir: Dispersions of metal sulfide nanoparticles (CdS, ZnS, PbS, and MnS) can be prepared directly by mixing the corresponding bulk solid with an appropriate ionic liquid, without further additives or solvents. The selection of the ionic liquid is critical for the viability of this nanoparticle preparation method.

The ionic liquids 1-methylpyridinium methylsulfate and 1-ethylpyridinium ethylsulfate were tested as solvents for the deterpenation by liquid-liquid extraction of citrus essential oil, simulated as a mixture of limonene and linalool. Liquid-liquid equilibrium data for the ternary systems limonene + linalool + 1-alkylpyridinium alkylsulfate (with th...

Real chemistry: Spectroscopic and crystallographic analyses confirm the chemical reaction of CO 2 with carbene present in 1,3- dialkylimidazolium acetate ionic liquids and the supporting role of the acetate ion. When CO 2 was bubbled through [C 2mim][OAc], formation of the corresponding imidazolium carboxylate, [C 2mim +-COO -], could be observed.

Contamination of medical devices with bacteria such as Meticillin resistant Staphylococcus aureus (MRSA) is of great clinical concern. Poly(vinyl chloride) is widely used in the production of medical devices, such as catheters. The flexibility of catheter tubing is derived from the addition of plasticisers. Here, we report the design of two dual fu...

Ammonia and/or oxygen were used to enhance the delignification of miscanthus dissolved in 1-ethyl-3-methylimidazolium acetate at 140°C. After dissolution of the gas at 9 bar, water was added as antisolvent to regenerate the dissolved biomass. In a next step, an acetone/water mixture was used to remove carbohydrate-free lignin from the regenerated b...

Three 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ionic liquids, namely, those with ethyl-, hexyl-, or decyl- as the alkyl substituent chain, were evaluated as potential solvents for the deterpenation of citrus essential oil by liquid−liquid extraction. The citrus essential oil was simulated as a mixture of the terpene limonene an...

Certain ionic liquids have been shown to dissolve cellulose, other biopolymers, and even raw biomass under relatively mild conditions. This particular ability of some ionic liquids, accompanied by a series of concurrent advantages, enables the development of improved processing strategies for the manufacturing of a plethora of biopolymer-based adva...

Mechanistic analysis of the reaction between elemental sulfur or selenium and 1,3-dialkylimidazolium acetate ionic liquids, in the absence of an external base or solvent, affords evidence for the equilibrium presence of carbene species in these ionic liquids. It demonstrates the potential to control, through anion selection, the concentration of ca...

A review of the scarce literature on the use of entirely liquid mixtures of ionic liquids and polymers in a solvent role is presented. These mixtures can present interesting characteristics such as very low volatility, good solvation ability, and tunable physical and thermal properties, and they can be especially attractive as solvent systems for c...

The liquid–liquid equilibrium (LLE) of the ternary system comprising heptane, thiophene and the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C2mim][NTf2]) was determined at 25°C and atmospheric pressure, for preliminary evaluation of the potential of this ionic liquid as solvent for the desulfurisation of transporta...

The liquid-liquid equilibria of three ternary systems comprising the aliphatic hydrocarbon octane, an aromatic hydrocarbon 1,n-(CH3)(2)C6H4 (where it takes the values 2, 3, or 4; that is, o-xylene, m-xylene, or p-xylene), and the ionic liquid 1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide [C(2)mim][NTf2]), were experimentally deter...

In common with many poly(ethylene glycol)s (PEGs), a poly(ethylene oxide)−poly(propylene oxide) random copolymer (EO−PO, with EO/PO = 1:1.3) of molecular weight 3320 g·mol−1, known as Sunbright-3320 (SB-3320), can be salted out of aqueous solution using kosmotropic salts such as (NH4)2SO4 to form aqueous biphasic systems (ABSs) comprising upper pol...

We have found that 1-alkyl-3-methylimidazolium chloride ionic liquids (ILs) can form immiscible liquid mixtures with some polyethylene glycols (PEGs). Binary mixtures of 1-ethyl-3-methylimidazolium chloride with PEG of molecular weight 1500, 2000, or 3400 g mol(-1), or of 1-butyl-3-methylimidazolium chloride with PEG of molecular weight 2000 or 340...

This research details our investigations into the potential for separating the ionic liquid trihexyl(tetradecyl) phosphonium chloride ([P-66614]Cl) from nonane using water. A miscible two component mixture of [P-66614]Cl and straight chain hydrocarbon separates upon addition of water into a three-phase mixture. The phase behaviour for [P-66614]Cl/w...

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Both softwood (southern yellow pine) and hardwood (red oak) can be completely dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim]OAc) after mild grinding. Complete dissolution was achieved by heating the sample in an oil bath, although wood dissolution can be accelerated by microwave pulses or ultrasound irradiation. It has b...

The liquid-liquid equilibria of two ternary systems comprising hexane, benzene and a bis{(trifluoromethyl)sulfonyl}amide ionic liquid, [A][NTf2] (where A = cation), have been determined at 40 degrees C. Specifically, the cations of the ionic liquids investigated are 1-ethylpyridinium, [C(2)py](+), and (2-hydroxyethyl)trimethylammonium, [N-111(C2OH)...

The ionic liquid 1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide ([C(2)mim][NTf2]) was tested as solvent for the separation of aromatic and aliphatic hydrocarbons containing 7 or 8 carbon atoms (the C-7- and C-8-fractions). The liquid-liquid equilibria (LLE) of the ternary systems (heptane + toluene + [C(2)mim][NTf2]) and (octane +...

Polyethylene glycol (PEG)-grafted aqueous biphasic extraction chromatographic (ABEC) resins have been shown to remove both mercury(II) cations (Hg2+) or perchlorate anions (ClO4−) from aqueous media under different conditions. Water destructuring (chaotropic) anions such as perchlorate (ΔGhyd = −214 kJ/mol) partitioned to ABEC resin in the presence...

Heat capacities and excess enthalpies were determined for three different binary water + ionic liquid systems, from (283.15 to 348.15) K, and covering the entire composition range. Specifically, the three completely water-miscible ionic liquids used were 1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate...

The recently discovered class of ionic liquids--mutually immiscible ionic liquids--are explored in this work for their first practical application: the separation of aromatic and aliphatic hydrocarbons by solvent extraction. For this preliminary approach, benzene and hexane were chosen as representatives of each group of hydrocarbons; the ionic liq...

The varied portfolio of applications of ionic liquids (ILs) is broadened in this work by presenting the possibility of their use as thermometric fluids in liquid-in-glass thermometers. Two ILs, namely tris(2-hydroxyethyl)methylammonium methylsulfate ([TEMA][MeSO4]) and trihexyl(tetradecyl)phosphonium bis{(trifluoromethyl)sulfonyl}amide ([P66614][NT...

Surface-active cellulose films for covalent attachment of bioactive moieties were achieved by codissolution of cellulose with polyamidoamine (PAMAM) dendrimers in an ionic liquid followed by regeneration of the composite as a film. Different generations of PAMAM were used for the formation of cellulose-dendrimer composites, as well as films with th...

In the last decade, the scientific community has witnessed a burgeoning research in ionic liquids. Numerous and diverse applications for them have been pointed out in the literature, with some processes based on ionic liquid technology already working in real plants. Among the possible fields of application, that of solvent extraction involving ion...

A modular, ionic liquid (IL)-based strategy allows compartmentalized molecular level design of a wide range of new materials with tunable biological, as well as the well known physical and chemical, properties of ILs, which thus deserve consideration as 'tunable' active pharmaceutical ingredients (APIs) with novel performance enhancement and delive...

The influence of the alkyl-substituent chain in 1-alkyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide ionic liquids ([C(n)mim][NTf(2)], where n is the length of a linear alkyl chain) as solvents for the separation of benzene and hexane by liquid extraction was investigated. The liquid-liquid equilibrium (LLE) at 25 degrees C for the terna...

The liquid-liquid equilibrium for the ternary system formed by hexane, benzene and the ionic liquid 1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide, [C(2)mim][NTf2], has been experimentally determined at 25 degrees C and 40 degrees C. The results show that the [C(2)mim][NTf2] can selectively remove benzene from its mixtures with hex...

Density and viscosity were determined for binary mixtures of water and three ionic liquids: 1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazolium trifluoroacetate, and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate. The experimental measurements of these properties were carried out at atmospheric pressure and temperatures fro...

This work presents the novel discovery of room-temperature ionic liquids that are mutually immiscible, some of which are also immiscible with solvents as diverse as water and alkanes; an archetypal biphasic system is trihexyltetradecylphosphonium chloride with 1-alkyl-3-methylimidazolium chloride (where the alkyl group is shorter than hexyl).

In this work, we have studied the use of homologous imidazolium-based ionic liquids (i.e. with the same fluorinated and non-fluorinated anion) to perform the separation of an ether and an alcohol. Concretely, we have selected ethyl tert-butyl ether (ETBE) and ethanol due to the capital interest of their industrial separation. Liquid–liquid equilibr...

In the last years, ionic liquids have emerged as a new class of compounds with negligible vapour pressure and excellent solvation properties, thus avoiding atmospheric contamination and flammable substances handling. Therefore, we can label ionic liquids as green solvents, constituting a very reliable alternative to traditional solvents. In this wo...

(Liquid+liquid) equilibrium data for the ternary system (dibutyl ether+methanol+water) were experimentally determined at T=(298.15, 308.15, and 318.15) K. The experimental results were correlated by means of the NRTL and UNIQUAC equations, the best results being achieved with the UNIQUAC equation, both for the individual correlations at each temper...

New experimental data at 25C for the density, velocity of sound, refractive index, and viscosity of aqueous solutions of DL-alanine and NaCl are reported. The apparent molar volume and isentropic compressibility of DL-alanine in aqueous electrolyte solutions have been calculated from the measured properties. The results show that DL-alanine exhibit...