Co-solvent Ratio Research Articles

Subcritical n-hexane/isopropanol extraction of lipid from wet microalgal pastes of Scenedesmus obliquus.

Subcritical co-solvents of n-hexane/isopropanol were primarily utilized to extract lipid from wet microalgal pastes of Scenedesmus obliquus. The effects of key operational parameters were investigated, and the optimal parameters were obtained: solvent ratio of n-hexane to isopropanol was 3:2 (V:V), phase ratio of co-solvents to microalgal biomass was 35:1 (mL:g), reactor stirring speed was 900rpm, extraction time was 60min. Additional pretreatment with acid, ultrasonic and microwave as well as enhanced subcritical pressure/heating treatments were also applied to further study their effects on lipid extraction. The results showed that the lipid recovery rate with acid pretreatment was 8.6 and 6.2% higher than ultrasonic and microwave pretreatment; the optimum enhanced subcritical condition was 55°C with atmospheric pressure. Under optimal operating conditions, the lipid and FAME yield were 13.5 and 7.2%, which was 82.6 and 135.1% higher than the traditional method. The results indicated that the subcritical n-hexane/isopropanol extraction process had promising application potential.

Evaluation of bioactivity of phenolic compounds from the brown seaweed of Sargassum fusiforme and development of their stable emulsion

This study investigated the antioxidant and anti-inflammatory activities of polyphenol compounds (PC) from Sargassum fusiforme. The PC were consequently applied as the functional ingredient in preparing facial cleaner emulsions. The effects of the ratio of cosolvent (glycerol and 1,2-propanediol) (RGl:PG) and mixing speed (Vm) on the droplet size and rheological behavior of the facial cleaner emulsions containing PC were also investigated. The PC of S. fusiforme showed a high total phlorotannin content (88.48 ± 0.30 mg PGE (100 mg)−1 extract), a high antioxidant activity (IC50 of 10.93 μg mL−1), and a high anti-inflammatory activity in the model 2 (inflammation prevention model). The antioxidant activity was better than that of the commercial antioxidant Trolox and the anti-inflammatory activity was similar to that of the anti-inflammatory chemical Dexamethasone. The facial cleaner emulsion containing the ratio of cosolvent of 1:1 and mixing speed of 300 rpm was found to be most stable as confirmed by minimal changes of mean diameter and microstructure within the examined storage period. This emulsion showed relatively higher viscosity, lower phase angle, stronger thixotropy, and exhibited similar non-Newtonian pseudoplastic behavior and thixotropy, as compared to two commercially available emulsions. The PC of S. fusiforme exhibited strong antioxidant and anti-inflammatory activities which could be employed as active ingredients in cosmetics. The stable cosolvent emulsion system was successfully established, providing a practical approach for application of S. fusiforme PC in the cosmetic industry.

Phase Behavior for Poly(vinylacetate) + Carbon Dioxide + Cosolvent Ternary Systems

Experimental cloud point and bubble point data of ternary mixtures for poly(vinylacetate) (PVAc) and cosolvents in carbon dioxide (CO2) are studied using the supercritical CO2 phase behavior device. The cloud point and bubble point pressures are determined by measuring the resistance variation of photoresistance. Acetate acid and ethyl acetate have been selected as the cosolvents. These systems show phase behavior over a temperature range of 308.2–338.2 K and pressure of up to 50 MPa. The transition point pressure increases as the temperature increases. The transition point isopleths for the PVAc + CO2 + cosolvent ternary systems show upper critical solution pressure types. The cloud point and bubble point curves for the PVAc + CO2 + cosolvent systems decrease rapidly as the cosolvent concentration increases. When the mass ratio of PVAc and cosolvents is fixed at 1:7, the transition point pressures increase as CO2 increases. Compared with acetic acid and ethyl acetate, the transition point pressures of th...

Enrichment, in vitro, and quantification study of antidiabetic compounds from neglected weed Mimosa pudica using supercritical CO2 and CO2-Soxhlet

ABSTRACTSupercritical fluid extraction (SFE) using carbon dioxide (CO2) and liquid CO2 using Soxhlet (CO2-Soxhlet) extraction were employed to extract three (3) antidiabetic compounds viz. stigmasterol, quercetin, and avicularin from Mimosa pudica. Various extraction parameters were studied. Extracts were analyzed pharmacologically, qualitatively and quantitatively to ascertain enrichment levels. All three antidiabetic compounds were effectively enriched under optimized conditions of temperature 60°C, pressure 40 MPa, co-solvent ratio 30%, and CO2 flow rate of 5 ml min−1. SFE was found to be the better method for enrichment of the antidiabetic compounds than the CO2-Soxhlet method. Extraction conditions were seen to affect the enrichment of desired compounds.

Polymerization and characterization of novel poly(acrylonitrile‐co‐styrene/pyrrole) nanoparticles: A comparison between microwave and conventional method

In this study, poly(acrylonitrile‐co‐styrene/pyrrole) or poly(AN‐co‐ST/Py) copolymer was successfully synthesized using microwave preparation technique, and its comparison with the conventional heating method is investigated. Different polymerization factors affecting on the preparation conditions and conversion yield such as monomer concentration, comonomers ratio, initiator concentration, cosolvent ratio, cosolvent type, polymerization temperature, and polymerization time have a considerable effect on the conversion yield %, functional groups, and molecular weight. The copolymerization process was approved by Fourier transform infrared, thermogravimetric analysis, 1H NMR spectroscopy, and gel permeation chromatography. The formation of poly(AN‐co‐ST/Py) nanoparticles was confirmed by SEM, and their possible formation mechanisms were also proposed. The SEM images of poly(AN‐co‐ST/Py) prepared by the microwave method showed that the synthesized copolymer had spikes or rods with spherical structure of the produced copolymers than the poly(AN‐co‐ST/Py) nanoparticles prepared by the conventional heating method. Microwave method showed advantages for the produced copolymers compared to that prepared by conventional method, where it can offer a copolymer in short time, high yield, and more thermally stable copolymers, rather than conventional method.

Controlling the composition, phase volume, and viscosity of microemulsions with cosolvent

Optimizing macroscopic properties of microemulsions (volume, composition, and viscosity) is tedious and often involves the use of an alcohol. We show that this optimization is possible when the alcohol acts as cosolvent (rather than a cosurfactant) to partition between the interface and bulk phases(s). Herein presented a phase behavior study of water, crude oil, tridecyl alcohol propoxy sulfate (C13-13PO-SO4), internal olefin sulfonate (C20-24IOS), and ethoxylated phenol (phenol-2EO) mixtures, rationalized by pseudophase theory and pseudoternary phase diagram. The detailed phase behavior study involved varying the surfactant concentration, cosolvent concentration, brine salinity, and oil content. High-performance liquid chromatography (HPLC) was used to determine the interfacial composition and steady and dynamic rheology to characterize the bicontinuous middle-phase samples. Measurements confirmed that phenol-2EO acted as cosolvent. A systematic shift of phase type is observed by increasing the cosolvent-to-surfactant content in the initial water/surfactant solution. Furthermore, it was observed that the interfacial ratio of cosolvent to surfactant controls the microemulsion composition, viscosity, and volume. This ratio is highly tunable, but when too high, a distortion of the middle phase is observed. The experimental results provide a methodology to tailor the composition of amphiphile mixture for optimizing microemulsion properties.

Synthesis, optimization, and characterization of poly (Styrene‐co‐Acrylonitrile) copolymer prepared via precipitation polymerization

AbstractPoly (Styrene‐co‐Acrylonitrile) (poly (St‐co‐AN) copolymer nanoparticles with controllable size are synthesized by a simple and cheap precipitation polymerization technique of styrene (St) and acrylonitrile (AN) monomers in aqueous medium using potassium persulfate (KPS) redox initiation system. Preparation of poly (St‐co‐AN) and studying all the parameters affecting the polymerization process such as time, temperature, monomer ratio, initiator molarity, cosolvent ratio, and solvent were considered. The resultant poly (St‐co‐AN) was compared with other studies which used different comonomers with AN, the comparison was assessed by evaluating the polymer conversion yield side. Maximum polymerization conversion yield, 66.5%, was obtained with St:AN (30%:70%) comonomer ratio. The smallest particle size obtained with this method was close to 16.17 nm and controlled by variation in polymerization conditions. The structure of poly (St‐co‐AN) copolymers were confirmed by Fourier transform infrared (FTIR), thermo gravimetric analysis (TGA), and differential thermal analyzer (DTA). The morphological structure of the copolymer particles was indicated by scanning electron microscope (SEM) photographs. The polymeric particle size was studied using particle size analyzer.

Supercritical fluid extraction of vinblastine from Catharanthus roseus

Catharanthus roseus is a rich source of alkaloids, being two dimeric alkaloids extensively used as antineoplastic drugs, vinblastine and vincristine. In this work was performed an optimization of the supercritical fluid extraction of vinblastine from C. roseus using ethanol as co-solvent for CO2 at different temperatures (40, 50, or 60°C) and pressure equal to 300bar. It was also evaluated the co-solvent ratio influence (2, 5 and 10% w/w). After HPLC/UV analysis the viability of this method of extraction was 92% more efficient for vinblastine extraction, when compared to traditional extraction methods such as solid-liquid extraction. The Lattice Boltzmann Method (LBM) was the explicit numerical method used in order to solve the one-dimensional diffusion-advection model, based on the differential mass balances written along the extraction bed. Regarding the parameter estimation, it was concluded that the axial dispersion term could be neglected from the mathematical model.

Extraction of total alkaloids, peimine and peiminine from the flower of Fritillaria thunbergii Miq using supercritical carbon dioxide

This study for the first time designed to use supercritical fluid extraction (SFE) to extract total alkaloids, peimine and peiminine from the flower of Fritillaria thunbergii Miq. 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt radical cation scavenging activity (ABTS-RSA) and ferric reducing antioxidant potential (FRAP) assay were selected to evaluate the antioxidant capacity of the extracts. A central composite design (CCD) with four variables (extract time (1.5–3.5) h, temperature (50–70)°C, pressure (15–35) MPa and co-solvent (ethanol: water) ratio (80–100, v/v) %was employed for optimization of process parameters, and response surface plots were constructed in accordance with a second order polynomial model. The highest yields of total alkaloids (2.9mg/g), peimine (0.7mg/g) and peiminine (0.07mg/g) were predicted at optimal conditions of 2.9h, 61.3°C, 30.6MPa and 90.3% ethanol and the antioxidant activity of the extracts was estimated to be comparable to that of α-tocopherol with ABTS value of 0.5mg/mL and FRAP value of 658mg AAE/100g, respectively. These results suggest that optimization of the extraction conditions is critical for accurate quantification of total alkaloids, peimine and peiminine, and antioxidants in F. thunbergii Miq flower, which may further be used for industrial extraction procedure.

Electrocatalytic Hydrogenation and Hydrogenolysis of Furfural and the Impact of Homogeneous Side Reactions of Furanic Compounds in Acidic Electrolytes

The electrochemical hydrogenation and hydrogenolysis (ECH) of furfural (FF) on a copper electrocatalyst has been investigated to produce biofuels and fine chemicals in an H-type batch reactor at room temperature. We report a systematic study of ECH of FF to gain a better understanding of the relationships between products and reaction conditions: current density, electrolyte, and cosolvent ratio in acidic solutions. The acidity of electrolytes had the most significant impact on the product distribution. Mildly acidic electrolytes mainly produced furfuryl alcohol (FA), while strongly acidic electrolytes produced both 2-methyl furan (MF) and FA. Also, the yield of products depended on the current density and reaction time when equivalent charge was transferred to the reaction. However, the mole balance accounting for FF, MF, and FA was not higher than 70% in any reaction condition when the theoretical amount of electrons for complete MF production from FF (e–/FF = 4) was transferred to the system. The inves...

Co-solvent ethanolysis of chicken waste: Optimization of parameters and characterization of biodiesel

ABSTRACT Fatty acid ethyl ester (FAEE) was developed from chicken waste. A blend of chicken fat and waste chicken oil was used as a feedstock for FAEE preparation via alkali-catalyzed transesterification with ethanol assisted by a co-solvent. Hexane was used as the co-solvent. The influences of alkali catalyst type and concentration, ethanol/blend molar ratio, hexane/ethanol volume ratio, temperature, time, and type of co-solvent on the yield of FAEE were investigated. The best yield of FAEE (96.94%~96.78% w/w ester content) was obtained at 0.75% KOH w/w, 8:1 ethanol/blend molar ratio, 1.5:1 hexane/ethanol volume ratio, 60°C temperature, and 60 min of reaction. The fuel properties of FAEE produced as well as its blends with petro diesel were within the range of those prescribed by ASTM D 6751 standards, indicating its suitability as fuel for combustion engines. It was concluded that the presence of co-solvent increased the yield of FAEE and enhanced its properties compared to FAEE produced via non-solvent processes. The process was found to follow first-order kinetics, and the activation energy was found to be 13.31 kJ/mol.

Modeling the effects of cosolvents on biodiesel production

In this study, a mathematical model is developed for predicting the effect of cosolvents on the biodiesel production, by taking into account the fact that the process consists of two liquid phases. The proposed model consists of a detailed chemical kinetic reaction mechanism and the phase equilibrium of the two phases. The experimental data for estimating the reaction rate constants consists of 1580 dynamic concentration data related to cosolvent-free systems. Then, the calculated reaction rate constants are used to model the biodiesel production process in systems containing cosolvents to investigate the cosolvent effects on the process. The average absolute relative deviation of 1.0% for all the experimental data points is a testament to the accuracy of the predictive model. Hence, the model was used to investigate the effect of methanol to oil ratio, the ratio of cosolvent to methanol, and the amount of catalyst on the biodiesel production rate and yield, in the presence of cosolvents tetrahydrofuran and diethyl ether. According to the results, the use of cosolvent leads to increase the reaction rates. In the other words, the process time is reduced; however, the final yield of biodiesel does not change. Comparison between two cosolvents shows that diethyl ether is more appropriate than tetrahydrofuran, because, in the use of diethyl ether, less cosolvent to methanol ratio is needed. Also, the effect of catalyst concentration is similar to the effect cosolvent.

Effects of Cosolvent Ratio on Fiber Characteristics of SwBKP during Alkali-Cosolvent Swelling System

Effects of Cosolvent Ratio on Fiber Characteristics of SwBKP during Alkali-Cosolvent Swelling System

스프레이 건조법을 이용한 PMMA/TiO<sub>2</sub> 다공성 입자 제조 및 특성 연구

본 연구에서는 분무 건조 공정을 이용하여 다공성 PMMA 입자 내부에 <TEX>$TiO_2$</TEX> 나노입자가 고르게 함침된 유/무기 복합분체를 제조하여, <TEX>$TiO_2$</TEX>의 은폐력은 그대로 유지하면서도 다공성 구조체로 피지를 흡유하여 지속성을 증대시키는 메이크업 화장품 소재로서의 가능성을 확인하고자 하였다. 끓는점이 다른 두 가지 공용매(디클로로메탄 및 헥산올)의 비율과 고분자의 농도 조절을 통해 입자크기와 기공크기를 제어할 수 있었으며, <TEX>$TiO_2$</TEX> 나노입자를 제조된 시료의 전체 무게 대비 74.6 wt%까지 함침 시킬 수 있었다. SEM 이미지 분석을 통하여 복합분체의 다공성 구조를 확인하였고, 절단면 이미지를 통하여 내부에 <TEX>$TiO_2$</TEX> 나노입자가 균일하게 함침 되어 있는 것을 관찰하였다. EDX 매핑으로 Ti 원소가 복합분체의 내부에 전체적으로 분포하고 있음을 확인하였다. Porosimetry 분석으로 기공사이즈 및 공극률을 측정하였으며, <TEX>$TiO_2$</TEX> 나노입자를 함침하고 있음에도 불구하고 50% 이상의 공극률을 유지하여 흡유량이 매우 뛰어남을 확인할 수 있었다. 결론적으로, <TEX>$TiO_2$</TEX> 나노입자가 PMMA입자의 내부에 잘 분산되어 있어서 가시광선의 반사율을 증가시킴으로써 피부의 결점을 커버하는 성능이 개선되었음을 확인하였다. Highly porous polymethyl methacrylate (PMMA) microspheres impregnated by <TEX>$TiO_2$</TEX> powder were prepared by spray drying method. The particle size and the porosity were controlled by optimizing the co-solvent ratio and the polymer concentration. <TEX>$TiO_2$</TEX> powder was impregnated into the microspheres upto 74.6 wt% content based on the weight of the resultant <TEX>$PMMA/TiO_2$</TEX> microspheres. SEM images showed that <TEX>$TiO_2$</TEX> powder was well distributed throughout the inside of the microsphere. EDX mapping showed that the Ti signal was well detected from every part of the microspheres, which was the evidence of the formation of the <TEX>$PMMA/TiO_2$</TEX> composite. Hg porosimetry result showed that the porosity was found to be over 50% regardless of the <TEX>$TiO_2$</TEX> contents. The final product was found to have high oil-absorbing capacity and great hiding power, both of which are key properties in designing the microsphere materials for make-up cosmetics application.

Chiral Nanostructures from Helical Copolymer-Metal Complexes: Tunable Cation-π Interactions and Sergeants and Soldiers Effect

Poly(phenylacetylene) (PPA) copolymers containing (R)- or (S)-MPA as minor chiral pendant can be forced to selectively adopt the right- o left-handed helix, in the presence of small amounts of Na(+) or Ag(+) ("Sergeants and Soldiers Effect") by addition of a donor cosolvent. The helical sense depends exclusively on the chiral monomer/donor cosolvent ratio, and this allows a perfect on/off tuning of the helicity of the copolymer. When the amount of the donor cosolvent is low, the metal ion complex is stabilized by a cation-π interaction, which is selectively cleaved when the amount of cosolvent is higher. Macroscopically chiral nanospheres and nanotubes composed by helical copolymers with P or M helical sense are also described. Our results demonstrate that it is possible to obtain the two enantiomeric helical structures (P and M helicities) and the corresponding nanospheres and nanotubes from a single helical copolymer, by controlled activation/deactivation of the Sergeant and Soldiers Effect with a donor cosolvent.

Textural analysis of SBA-15 molecular sieve using ethanol as co-solvent

The SBA-15 molecular sieve has been widely studied due to its unidirectional mesoporous structure, high average pore diameter and high thermal and hydrothermal stability. This study aimed to evaluate the effect of ethanol co-solvent in the texture of SBA-15 molecular sieve, performing the synthesis process in different proportions of co-solvent ethanol. The SBA-15 molecular sieve was synthesized by adopting the following molar composition of reaction mixture: 1TEOS: 0.017 P123: 5.7 HCl: 173 H2O: x EtOH. In which X took the values 10, 20, 30 and 40 due to the ethanol co-solvent ratio. Analyzing the X-ray diffractograms, it was possible to observe a greater structural organization for a higher molar proportion of co-solvent. The micrographs showed agglomerates of spherical particles which by increasing molar proportion of ethanol co-solvent became larger and more defined. By the BET method, it was observed that as the proportion of co-solvent increased the specific surface area also increase and a decrease in micropores occurred, pointing to the porous nature of the material. The walls of the material became thicker as it increased the proportion of co-solvent making it the most stable material.

Supercritical fluid extraction of phycocyanin and investigation of cytotoxicity on human lung cancer cells

In this study, a step-by-step optimization approach was carried out for supercritical fluid extraction (SCF) of phycocyanin (PC) from Spirulina platensis, where pressure, temperature, co-solvent ratio and process duration were investigated. The elicited parameters were 250bar, 60°C, 10% ethanol as co-solvent at a dynamic duration of 45min yielding PC amount of 90.74% and PC purity of 75.12%. Extracts obtained with SCF were tested against lung cancer cell line (A549) to determine cytotoxicity and compared to that obtained from solvent extraction. SCF extract had an IC50 value of 26.82μg/mL, whereas that value was 36.94μg/mL for solvent extract indicating a lower cytotoxic effect. Overall, the results revealed significant information for PC extraction using supercritical fluids as an alternative to conventional methods and the possibility to include PC in daily diet for preventive purposes against highly lethal lung cancer.

Laboratory validation of method of solvent extraction for removal of sulphur compounds from mineral oil

The presence of corrosive sulphur compounds in mineral oil is a serious problem affecting the life of transformers. There are several techniques available to remove corrosive sulphur and among them the method of solvent extraction is useful for complete removal of sulphur compounds. In this investigation, laboratory experiments were carried out to validate method of solvent extraction for removal of sulphur compounds like Dibenzyl disulphide and Mercaptan sulphur from mineral oil. The optimum oil to solvent ratio, solvent to co-solvent ratio are investigated and discussed. Efficiency of method of solvent extraction for removal of sulphur compounds is demonstrated on a laboratory scale and further improvements to properties of mineral oil is proposed by the use of conventional reclamation techniques.

Fabrication of poly(methyl methacrylate) and TiO2 composite microspheres with controlled morphologies and porous structures by electrospraying

This paper describes the fabrication of porous poly(methyl methacrylate) (PMMA) and PMMA/TiO2 composite microspheres by electrospraying in a humid chamber. The effects of polymer concentration, co-solvent ratio, and relative humidity on morphology were evaluated to prepare microspheres with well-defined porous structures. Dichloromethane and hexanol were used as the solvent and co-solvent in solvent mixture for PMMA, respectively. The optimized conditions were established as 4 wt% for PMMA concentration, 10 wt% for hexanol ratio, and 60 % for relative humidity. The resultant PMMA microspheres exhibited a spherical morphology and a highly porous structure. Among the process variables, relative humidity was found to be a critical factor for the development of large surface pores. In addition, PMMA/TiO2 composite microspheres with a highly porous structure were prepared by simply mixing TiO2 nanopowders in a PMMA solution before electrospraying. Energy-dispersive X-ray spectroscopy confirmed that the TiO2 nanopowders were well distributed throughout the composite microspheres. Our results clearly indicate that porous PMMA and PMMA/TiO2 microspheres have potential uses as catalyst carriers, sensors, and in cosmetics, among other possibilities.

Enzymatic synthesis, purification and identification of bioactive trehalose ester derivatives for health applications

In the present work, we attempted to produce novel trehalose ester derivatives catalyzed by lipase using trehalose and lipoic acid as substrates. Our aim was to select the lipase with the highest catalytic efficiency as a biocatalyst to efficiently produce trehalose ester derivatives with the lowest production cost for further industrial applications. The highest conversion yields of trehalose lipoate (75.9±1.9%) were obtained at the following optimal conditions: reaction temperature 40°C, reaction time 4 days, substrate molar ratio 1:4 (trehalose:lipoic acid), total enzyme activity 3000 PLU (propyl laurate units), four stepwise additions of lipoic acid (0.03mmol/day) and a cosolvent ratio of 4:1 [DMSO:2-methyl-2-butanol(2M2B)]. After isolation and purification, the carboxyl group of lipoic acid was determined to be connected to the C6 hydroxyl group of trehalose using nuclear magnetic resonance. The DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging activity (%) of purified 6-o-trehalose lipoate was at least 2.5-fold higher than that of lipoic acid. This bioactive trehalose ester exhibits improved antioxidant activity, which may have higher health benefits than those of lipoic acid, in various functional product applications.