The objective this study was to evaluated the influence of silica modified with protic ionic liquid (PIL) on an immobilized biocatalyst by covalent binding of Burkholderia cepacia lipase (BCL) in a PBR and in the transesterification reaction, by characterization and mass transfer of the system studied. The results showed that maximum conversion of ethyl esters was 39 ± 1.73% at 96 h (IB on control silica) and 47 ± 2.0% in 72 h (IB on modified silica). The PIL also influenced the analysis of residence time distribution (RTD) with the mean time ranging from 14.94 (control silica) to 25 min (modified silica). Variation of the reaction parameters (temperature, flow rate and molar ratio) positively influenced the mass transfer coefficient (kc) which varied from 0.95 × 10−4 to 2.39 × 10−4 m s−1 (IB on control silica) and from 1.22 × 10−4 to 3.06 × 10−4 m s−1 (IB on modified silica).

Abstract Ionic liquids (ILs) are organic salts with low volatility and have different applications including organic synthesis, separation and extraction processes, fuel cell electrolyte, surfactants, among others. Protic ILs based on the N-methyl-2-hydroxyethyl ammonium cation and short chain carboxylic anions have simple synthesis and purification. However, as new substances few data are available for their thermodynamic properties and phase equilibria. In order to investigate the partition of these substances in alcohol-water, liquid-liquid equilibria data were determined experimentally for three ionic liquids (formed by the cation N-methyl-2-hydroxyethyl ammonium (m-2HEA) and the anions propionate (Pr), butanoate (B) and pentanoate (P)) with butanol and pentanol, at three different temperatures: 293.15K, 313.15K and 333.15K. The binodal curves are obtained by the turbidity method with gravimetric determination of all the components, curves are fitted using the Merchuk method. The tie-lines are also gravimetrically determined. The results confirm the high hydrophilicity of these ionic liquids, with partition coefficients of water-butanol and water-pentanol lower than 1. Data were correlated with UNIFAC.

Among the applications for protic ionic liquids (PILs), lubrication is one of the newest and the most promising. In this work, ammonium-based protic ionic liquids were tested as lubricant fluids for aluminum-steel contacts. PILs were synthesized with 2-hydroxyethylamine (2HEA) and a carboxylic acid (formic and pentanoic), aiming to understand the effect of two different anion chain lengths on the lubricant behavior. The synthesized PILs were characterized by RMN, FTIR and TGA. Wear tests, conducted using a ball-on-plate configuration, showed that the increase of the anion carbon chain length in the PIL structure reduced significantly the coefficient of friction value. Besides, after the wear tests, the PILs structural integrity was not affected. In the same way, bending under tension (BUT) tests evidenced that the performance for stamping conditions of the PIL with the longest anion carbon chain was similar to that of the commercial lubricant. Since, both formed a uniform tribofilm, developed the same lubrication regime and the drawing forces values were close and constant. Hence, the ionic liquid obtained with 2HEA and pentanoic acid (2HEAPe) is as suitable as the commercial lubricant for metal forming processes.

Mesoporous silica supports (aerogels) were used to immobilize Burkholderia cepacia lipase (BC) by encapsulation (EN or ENIL), physical adsorption (ADS or ADSIL) and covalent binding (CB or CBIL) into or onto the aerogel modified with protic ionic liquid (PIL). Yield immobilization (Ya) and operational stability were determined by the hydrolytic reaction of olive oil. Ya (37% to 83% by physical adsorption) and operational stability (2 to 23 batches by encapsulation) increased when the support was modified with PIL. For immobilized derivates observed by the BET method, in this case ADS and CB for ADSIL and CBIL, increased pores size was observed, possibly due to the higher amount of BC immobilized conferring Ya and operational stability. This effect was probably attributed to the entry of the enzyme into the pores of the silica aerogel structure. SEM images showed a change in the structure and properties of immobilized lipase derived with PIL. A characteristic FTIR band was obtained for the silanol groups and amides I, IV and V, demonstrating the efficiency of immobilization of BC. The most efficient biocatalysts were ADSIL with regard to yield immobilization and ENIL for operational stability.

Lipase from Burkholderia cepacia was immobilized in a silica matrix and dried in high pressure carbon dioxide media (aerogel). The protic ionic liquid (PIL) was used in the immobilization process by encapsulation. The objective of this work was to evaluate the influence of the drying technique using supercritical carbon dioxide in biocatalysts obtained through the sol-gel technique by evaluating temperature and pressure and, after selecting the best drying conditions, to investigate the application of the technique for the biocatalyst using ionic liquid as an additive in the immobilization process. The results for immobilized biocatalysts showed that the best conditions of pressure and temperature were 100 bar and 25 ºC, respectively, giving a total activity recovery yield of 37.27% without PIL (EN) and 44.23% with PIL (ENLI). The operational stability of the biocatalysts showed a half-life of 11.4 h for ENLI and 6 h for EN. Therefore, solvent extraction using supercritical CO2, besides shortening drying time, offers little resistance to the immobilization of lipases, since their macropores provide ample room for their molecules. The use of the ionic liquid as an additive in the process studied for the immobilization of enzymes produced attractive yields for immobilization and therefore has potential for industrial applications in the hydrolysis of vegetable oils.

En el presente trabajo, se llevó a cabo un estudio de corrosión causada por distintos líquidos iónicos sobre placas de acero al carbón A285 grado A, a temperatura ambiente. Se prepararon los líquidos iónicos por neutralización de monoetanolamina con ácidos carboxílicos. El carácter hidrofílico o hidrofóbico de los líquidos se determinó a través de la técnica de humectabilidad. El análisis de corrosión se llevó a cabo por técnicas electroquímicas (potencial de circuito abierto y polarización potenciodinámica). Se realizó un análisis de la morfología del sustrato, antes y después de los análisis electroquímicos, por microscopía electrónica de barrido acoplada con espectroscopía de rayos X por dispersión de energía. Los resultados muestran pequeñas tasas de corrosión para el acero al carbono A285 grado A en contacto con los líquidos iónicos, de las cuales la superior se mostró con lactato de 2-hidroxietanolamina y la más baja con acetato de 2-hidroxietanolamina.

In this work, corrosion caused by different ionic liquids on Grade A - A285 carbon steel plates at room temperature (25°C) is studied. Ionic liquids were prepared via acid - base neutralization. The ionic liquid hydrophilic or hydrophobic character was determined by the wettability technique. Corrosion behavior for each system was analyzed by electrochemical measurements (open circuit potential monitoring and potentiodynamic polarization). Substrate morphology was analyzed by scanning electron microscope and energy dispersive X-ray spectroscopy before and after the electrochemical measurements. The results obtained showed that Grade A - A285 carbon steel in contact with the ionic liquids presented low corrosion rates, being the highest one the corresponding for the 2-hydroxyethylamominum lactate system and the lowest corrosion rate for 2-hydroxyethylammonium acetate system.