Amount Of Cosolvent Research Articles

Expanded Kinetic Control for Persistent Micelle Templates with Solvent Selection

The precision control of nanoscale materials remains a challenge for the study of nanostructure-performance relationships. Persistent micelle templates (PMT) are a kinetic-controlled self-assembly approach that decouples pore and wall control. Here, block copolymer surfactants form persistent micelles that maintain constant template size as material precursors are added, despite the shifting equilibrium dimensions. Earlier PMT demonstrations were based upon solvent mixtures where kinetic rates were adjusted with the amount of water cosolvent. This approach is however limited because ever-higher water contents can lead to secondary porosity within the material walls. Herein, we report an improved method to regulate the PMT kinetics via the majority solvent. This enables a new avenue for the expansion of the PMT window to realize templated materials with a greater extent of tunability. In addition, we report a new small-angle X-ray scattering (SAXS)-based log-log analysis method to independently test the micelle-templated series for consistency with the expected lattice expansion with an increasing material:template ratio. The PMT window identified by the log-log analysis of the SAXS data agreed well with independent scanning electron microscopy measurements. The combination of improved micelle control with solvent selection along with SAXS validation will accelerate the development of a myriad of nanomaterial applications.

Supercritical transesterification of microalgae triglycerides for biodiesel production: Effect of alcohol type and co-solvent

In the present study, biodiesel produced by supercritical transesterification (non-catalytic) from Spirulina oil with alcohol (methanol and ethanol) was investigated. A factorial experimental design 22 with two central points for each alcohol was used. The effect of temperature (200 and 300 °C) and the amount of co-solvent (0.0005–0.003 g CO2/g methanol and 0.0003–0.001 g CO2/g ethanol) on the reaction yield was studied. Results showed that yield increased from 42% to 65% (at 200 °C) and from 46% to 72% (at 300 °C) when the amount of CO2 increased from 0.0005 to 0.003 g CO2/g methanol. By using CO2 as a co-solvent, it is possible to reduce the critical point of the reaction mixture (oil + alcohol) and thereby increase the reaction yield. For ethanolysis, the effect of selected variables was not statistically significant in the range of studied reaction conditions.

Optimizing the Supercritical Fluid Extraction of Lutein from Corn Gluten Meal

Supercritical CO2 was used to extract xanthophylls from corn gluten meal (CGM). Data from a Box-Behnken experimental design was used to model optimal lutein extraction based on extraction temperature (40–80 °C), pressure (5500–7500 psi), and fraction of ethanol co-solvent added (5–15% by volume of total solvent). Lutein extraction was also strongly correlated with zeaxanthin extraction with a correlation coefficient (r) of 0.995. The response surface model for lutein extraction indicated that the amount of co-solvent had the largest impact (p < 0.001) on lutein extraction yield. Influence of temperature and pressure were limited to quadratic or interaction effects (p < 0.15). The optimal lutein extraction conditions predicted with the model were a temperature of 40 °C, pressure of 6820 psi, and co-solvent (ethanol) addition of 15% by volume. At these conditions, lutein recovery from CGM was 2.6 times higher than the amount recovered with a quintuple extraction using ethanol and chloroform/dichloromethane (2:1). The strong linear effect of co-solvent addition suggests the possibility of further increasing lutein extraction with the addition of more co-solvent. CGM protein loss during extraction was also calculated and determined to be negligible.

Phase behaviors for the poly(2-phenylethyl methacrylate) in supercritical fluid solvents: Experiment and PC-SAFT EoS

In this work, the experimental cloud-points in the binary and ternary mixtures for poly(2-phenylethyl methacrylate) [P(2-PEMA)] solutions containing supercritical solvents (i.e., carbon dioxide, propylene, 1-butene, dimethyl ether (DME)) are carried out up to 473K and 224MPa. According to the amount of cosolvent (i.e., DME), the cloud-point curves for ternary mixtures of P(2-PEMA) in supercritical solvents (i.e., carbon dioxide, propylene, 1-butene) show the changes from upper critical solution temperature (UCST) behavior to lower critical solution temperature (LCST) behavior. The PC-SAFT equation of state is applied to correlate the phase behaviors of all experimental systems, and the calculated results are shown as a reasonable agreement with experimental data. According to the amount of DME (i.e., cosolvent), the UCST- and LCST-type phase behaviors are described exactly by PC-SAFT EoS with one adjustable binary interaction parameter on which the effect of temperature and/or cosolvent amount is not considered.

Supercritical Fluid Extraction of Bioactive Compounds from Plant Materials.

There has been growing interest in the application of supercritical solvents over the last several years, many of the applications industrial in nature. The purpose of plant material extraction is to obtain large amounts of extract rich in the desired active compounds in a time-sensitive and cost-effective manner. The productivity and profitability of a supercritical fluid extraction (SFE) process largely depends on the selection of process parameters, which are elaborated upon in this paper. Carbon dioxide (CO2) is the most desirable solvent for the supercritical extraction of natural products. Its near-ambient critical temperature makes it suitable for the extraction of thermolabile components without degradation. A new approach has been adopted for SFE in which the solubility of nonpolar supercritical CO2 can be enhanced by the addition of small amounts of cosolvent.

Assessing the efficiency of imidazolium-based ionic liquids on the phase behavior of a synthetic biomedical thermoresponsive polymer

HypothesisTemperature-responsive polymers (TRPs) with a phase transition temperature close to human physiological body temperature have attracted much attention in biomedical and pharmaceutical fields. Addition of small amount of cosolvent to TRPs is expected to influence the molecular interactions, thereby affecting the phase transition temperature of TRPs. Hence, it is possible to tune the phase behavior of TRPs and also drive transitions in TRPs by variation of chemical structure of cosolvent. ExperimentsTo elucidate the conformational changes of the phase transition of TRP aqueous solution in ionic liquids (ILs), poly(N-vinylcaprolactam) (PVCL), a well known TRP was synthesized by solution polymerization. The lower critical solution temperature (LCST) behavior of polymer aqueous solution, with the addition of imidazolium-based ILs possessing same Cl− anion and a set of cations [Cnmim]+ such as 1-ethyl-3-methylimidazolium ([Emim]+), 1-butyl-3-methylimidazolium ([Bmim]+), 1-hexyl-3-methylimidazolium ([Hmim]+), 1-decyl-3-methylimidazolium ([Dmim]+), 1-allyl-3-methylimidazolium ([Amim]+) and 1-benzyl-3-methylimidazolium ([Bzmim]+), was monitored by using various sophisticated experimental techniques. FindingsThe modulations on the LCST of PVCL aqueous solutions follow the order of [Emim][Cl]<[Amim][Cl]<[Bmim][Cl]<[Hmim][Cl]<[Bzmim][Cl]<[Dmim][Cl]. This order shows that the LCST value increase with increasing the alkyl chain length of cation from [Emim]+ to [Dmim]+ of IL. To the best of our knowledge, this is the first report on comprehensive unequivocal evidence of the phase transition behavior of PVCL in presence of imidazolium-based ILs.

Trans-esterification of waste cooking oil with methanol by electrolysis process using KOH

Biodiesel produced form waste cooking oil (WCO) has increasingly attracted the attentions as an alternative fuel due to lower particulate emissions and other beneficial factors such as low cost. The present study investigated the production of biodiesel (BFD) as one of the effective methods in solving energy crises and environmental pollution. To increase the consumption of biofuels, a high yield biodiesels (96%) was produced as an alternative to fossil fuels by electrolysis method using graphite electrodes through trans-esterification reaction of WCO and KOH in presence of methanol. This reaction was done in 2 h without side saponification reaction. Biodiesel decreases the environmental effects of waste oil and can cause a new application for using the waste oil. The effect of the catalysis amount, oil/alcohol molar ratio, the amount of co-solvent, water amount, reaction temperature, voltage and the reaction time on biodiesel production were investigated confirming this method as a highly effective way for obtaining high yields. Increasing the catalyst beyond a known level decreases the reaction yield due to saponification side reactions; in consequence, an optimum amount of the catalyst should be used. Without inserting the electricity current in the environment temperature, trans-esterification reaction is done slightly in a long time but proper voltage should be used to obtain high yield, complete the reaction and decrease the reaction time. The purpose of this study is to show that the rheology of the biodiesel is a strong function of the shear history.

Reverse micellar extraction of lactoferrin from its synthetic solution using CTAB/n-heptanol system.

The partitioning of Lactoferrin (LF) into the reverse micellar phase formed by a cationic surfactant, cetyltrimethylammonium bromide (CTAB) in n-heptanol from the synthetic solution of LF was studied. The solubilization behaviour of LF into the reverse micellar phase and back extraction using a fresh stripping phase were improved by studying the effect of processing parameters, including surfactant concentration, solution pH, electrolyte salt concentration and addition of alcohol as co-solvent. Forward extraction of 100% was achieved at CTAB concentration of 50mM in n-heptanol solvent, pH of 10 and 1M NaCl. The electrostatic force and hydrophobic interaction have major influence on LF extraction during forward and back extraction respectively. The size of the reverse micelles and their corresponding water content were measured at different operating conditions to assess their role on the LF extraction. The present reverse micellar system has potential to solubilise almost all the LF into the reverse micelles during forward extraction and could able to allow back extraction from the reverse micellar phase with addition of small amount of co-solvent.

Measurement of Microemulsion Viscosity and Its Implications for Chemical Enhanced Oil Recovery

Summary The rheological behavior of microemulsion systems was systematically investigated with mixtures of oil, brine, surfactant, cosolvent, and in some cases polymer to determine their effects. A microemulsion-rheology model was developed and used to interpret the experimental results. The optimal microemulsion/oil-viscosity ratio without cosolvent was roughly 5:6, but it can be reduced to a more favorable ratio of approximately 2 by adding cosolvent. Even though the amount of cosolvent needed is case dependent, a clear trend of microemulsion-viscosity reduction with increasing cosolvent concentration was observed. Limited evidence suggests that large hydrolyzed polyacrylamide (HPAM) molecules with a narrow molecular-weight (MW) distribution have negligible partitioning to Type II and Type III microemulsions.

Palladium catalyzed methoxycarbonylation of 1-dodecene in biphasic systems – Optimization of catalyst recycling

The palladium catalyzed methoxycarbonylation of long-chain olefin 1‐dodecene in a liquid/liquid biphasic system composed of methanol as polar phase and the substrate/product as nonpolar phase is reported. The immobilization of the palladium based catalyst in the methanol phase is affected by the use of the watersoluble ligand SulfoXantPhos and methanesulfonic acid as co‐catalyst. We investigated these systems with respect to reaction performance and catalyst recycling by variation of the type and amount of co-solvent in both existing phases. By modifying these systems with a co-solvent, catalyst recycling could be improved compared to the benchmark system without co-solvents to a palladium and phosphorous leaching <1ppm. The applied homogeneously dissolved palladium catalyst could be quantitatively recycled four times via a simple phase separation without any loss in activity and selectivity.

Identification of an Imine Reductase for Asymmetric Reduction of Bulky Dihydroisoquinolines.

A new imine reductase from Stackebrandtia nassauensis (SnIR) was identified, which displayed over 25- to 1400-fold greater catalytic efficiency for 1-methyl-3,4-dihydroisoquinoline (1-Me DHIQ) compared to other imine reductases reported. Subsequently, an efficient SnIR-catalyzed process was developed by simply optimizing the amount of cosolvent, and up to 15 g L-1 1-Me DHIQ was converted completely without a feeding strategy. Furthermore, the reaction proceeded well for a panel of dihydroisoquinolines, affording the corresponding tetrahydroisoquinolines (mostly in S-configuration) in good yields (up to 81%) and with moderate to excellent enantioselectivities (up to 99% ee).

Synthesis of CuO/SBA-15 nanocomposite in ternary system of CO2, inorganic salt and co-solvent

Highly dispersed CuO nanoparticles were successfully synthesized within mesoporous silica in supercritical CO2 using inorganic Cu precursors. Co-solvent and deposition time were found to have significant influence on the metal loading and the morphology of the nanophase. The agglomerates of nanoparticle outside the SBA-15 channels were obtained, whose size were about 20–80nm, when ethanol, 1,3 propylene glycol and n-butyl alcohol were used as co-solvent, although the inorganic precursor has large solubility in them. When ethylene glycol was used as co-solvents, large amounts of continuous nanowires were found inside the SBA-15 channels. However, when the mixture of ethylene glycol and water were used as co-solvent, short nanorods or even nanoparticles were found instead. It indicates that the role of the co-solvent may have many aspects, such as enhancement of the precursor dissolution, change of the interaction between the precursor and the substrates and so on. In addition, it was found that a larger amount of co-solvent had negative effect on the metal loading, mainly due to the phase separation of the ternary system of supercritical CO2, co-solvent and inorganic precursors.

Enhancement of biodiesel synthesis using co-solvent in a packed-microchannel

Abstract Biodiesel synthesis over calcium oxide (CaO) catalyst in a packed-microchannel was enhanced by using iso-propanol as co-solvent. The influence of operating conditions on the biodiesel synthesis was studied by applying Box–Behnken design (BBD) with the response surface methodology (RSM). The improved reaction efficiency was associated with the less required residence time of reaction and methanol-to-oil molar ratio. The optimal conditions were found at the residence time of 6.5 min, methanol-to-oil molar ratio of 20:1, and co-solvent amount of 14.5 wt.% providing the purity of methyl esters of 99%. The superior productivity of our reactor with energy saving was also presented.

Co-Solvent Facilitated in situ Esterification of Cellulose in 1-Ethyl-3-Methylimidazolium Acetate

The homogeneous conversion of cellulose to cellulose propionate with propionic acid anhydride in the ionic liquid 1-ethyl-3-methylimidazolium acetate and two different co-solvents, dimethyl sulfoxide and 1-methylimidazole, was studied. The software MODDE was used to generate an experimental design and evaluate the significance of the studied parameters. The methods 1H and 13C nuclear magnetic resonance (NMR) spectrometry and ion chromatography were used to analyze the obtained materials both qualitatively and quantitatively. The NMR spectrometry of dissolved cellulose esters confirmed there was covalent bonding with an even distribution pattern. From both ion chromatography and NMR spectroscopic data, it was concluded that by adding large amounts of co-solvent and using a high reagent-to-anhydroglucose unit ratio, it was possible to reduce the amount of acetylation caused by acetate anions in the ionic liquid. At the same time, it was shown that the reaction time and temperature was not at all significant in this respect. There was no notable difference detected in the degree of substitution between the reactions performed using dimethyl sulfoxide or 1-methylimidazole as a co-solvent.

Trinuclear Ruthenium Macrocycles: Toward Supramolecular Water Oxidation Catalysis in Pure Water

The incorporation of a Ru(bda)(bda = 2,2′-bipyridine-6,6′-dicarboxylate) water oxidation catalyst into a trinuclear metallosupramolecular macrocycle leads to increased stability and activity compared to the mononuclear reference system. To overcome solubility problems of such large structures in water and the need for large amounts of organic cosolvents, new macrocyclic water oxidation catalysts with improved water solubility become desirable. With triethylene glycol side chains, the required amount of acetonitrile as a cosolvent was halved, whereas the application of charged ammonium side chains allowed catalysis in pure water. The catalytic activity was found to be comparable to the parent compound. Kinetic experiments were performed to explain the rate differences between those new derivatives and showed that Coulombic repulsion between the charged side chains and CeIV leads to slower oxidation processes.

Influence of cosolvent retention on film formation and surface mechanical properties of water based acrylic coatings by atomic force microscopy

Abstract The influence of several common cosolvents on the level of film formation and surface mechanical properties of water-based acrylic coatings is investigated by atomic force microscopy (AFM) and AFM based nano-indentation technique. The amount of residual cosolvents in the coatings is determined and it is found that the aforementioned properties of coatings with the exact same polymer composition can be significantly different depending on the amount of residual cosolvents, which is related to the evaporation rate of the solvent as well as the interaction between the solvent, water and the polymer. Butyl glycol, for example, has good interaction with the acrylic polymer and water but due to its fast evaporation, does not improve film formation. Texanol, on the other hand, presents in the film at a large amount but it reduces the surface stiffness of the film and can have a detrimental effect on the surface mechanical properties of the coating.

Supercritical fluid extraction of Bulgarian Achillea millefolium

Achillea millefolium L. (yarrow) from Bulgaria was extracted in a supercritical pilot-scale plant using carbon dioxide (CO2). First, the extraction yield was studied as a function of time at 14MPa, 40°C and 70g/min of CO2. Then, the extraction time was set in order to study the effect of different process parameters (pressure, temperature, CO2 flow and use of ethanol as co-solvent) on the extraction yield. The composition of the volatile oil obtained in yarrow extracts was thoroughly studied by GC–MS.Overall extraction yield increased with pressure, temperature and amount of co-solvent. Nevertheless, minor effect of the studied process parameters on yarrow volatile oil profile was found. On the other hand, important differences were found when comparing the volatile oil composition of Bulgarian Achillea millefolium L. extracts with those obtained from other origins.

In-situ transesterification of wet spent coffee grounds for sustainable biodiesel production

This work addresses in-situ transesterification of wet spent coffee grounds (SCGs) for the production of biodiesel. For in-situ transesterification process, the methanol, organic solvent and acid catalyst were mixed with wet SCG in one pot and the mixture was heated for simultaneous lipid extraction and transesterification. Maximum yield of fatty acid methyl esters (FAME) was 16.75wt.% based on the weight of dry SCG at 95°C. Comprehensive experiments were conducted with varying temperatures and various amounts of moisture, methanol, co-solvent and acid catalyst. Moderate polar and alcohol-miscible organic solvent is suitable for the high FAME yield. Unsaturated FAMEs are subject to oxidative cleavage by nitric acid and shorter chain (C6 and C10) FAMEs were mainly produced while sulfuric acid yielded long chain unsaturated FAMEs (C16 and C18). Utilization of wet SCGs as a biodiesel feedstock gives economic and environmental benefits by recycling the municipal waste.

The study of microalgae Nannochloropsis salina fatty acid composition of the extracts using different techniques. SCF vs conventional extraction

The extraction of lipids and other valuable components from microalgae (Nannochloropsis salina) has been performed using various conditions: pure SC-CO2; SC-CO2+acetone (at 32MPa and 40°C); Soxhlet apparatus with n-hexane; and Soxhlet apparatus with chloroform. Small amounts of co-solvents (3.2wt.% of acetone) were added to modify the polarity and solvent strength of the supercritical CO2 to increase the solute solubility and to minimize operating costs of the extraction process. The extractions of lipids from algae were performed using a laboratory scale SCF extraction experimental apparatus. High pressure supercritical reactor with volume of 993cm3, which made from stainless steel, was used. The flow rate of SCF was maintained constant (1.5±0.05kg/h). The extraction time was within 1.5h. Four extracted lipid fractions were collected separately for each extraction conditions (for pure CO2 and CO2+co-solvents) and analyzed using GC–MS. The experimental results showed that extraction technique is negligible small affecting on total extract yields and fatty acids content.

Process development for oxidations of hydrophobic compounds applying cytochrome P450 monooxygenases in-vitro

Cytochrome P450 monooxygenases are a unique family of enzymes that are able to catalyze regio- and stereospecific oxidations for a broad substrate range. However, due to limited enzyme activities and stabilities, hydrophobicity of substrates, as well as the necessity of a continuous electron and oxygen supply the implementation of P450s for industrial processes remains challenging. Aim of this study was to point out key aspects for the development of an efficient synthesis concept for cytochrome P450 catalyzed oxidations. In order to regenerate the natural cofactor NADPH, a glucose dehydrogenase was applied. The low water soluble terpene α-ionone was used as substrate for the model reaction system. The studies reveal that an addition of surfactants in combination with low volumetric amounts of co-solvent can significantly increase substrate availability and reaction rates. Furthermore, these additives facilitated a reliable sampling procedure during the process. Another key factor for the process design was the oxygen supply. Based on various investigations, a bubble-aerated stirred tank reactor in batch mode represents a promising reactor concept for P450 oxidations. Main restriction of the investigated reaction system was the low process stability of the P450 monooxygenase, characterized by maximum total turnover numbers of ∼4100molα‐ionone/molP450.