Methanol Volume Ratio Research Articles

Self-Assembly of Polyoxometalate-Based Starlike Polymers in Solvents of Variable Quality: From Free-Standing Sheet to Vesicle

Polyoxometalate-based supramolecular star polymers, where an anionic polyoxometalate is closely encapsulated by a hydrophobic shell of cation terminated polystyrenes, are conceptually regarded as a model of star polymers to study their intra- and interstar interactions and self-assembled behaviors in solvents of variable quality. These model stars can self-assemble to form unilamellar free-standing sheets in the toluene/methanol mixture solvent with a methanol volume ratio of 50%. An increase in the methanol content to 75% or 80% results in a coexistence of free-standing sheets with vesicles, where several intermediates are captured for the morphological evolution from sheet to vesicle. With further increasing methanol content to 90%, pure vesicle phases form with unilamellar or oligolamellar features. All these aggregates are packed by the totally hydrophobic starlike polymers, where the core–shell structures are retained. This is distinctly different from the bilayered nanostructures formed by amphiphil...

<i>In Situ</i> Methanolysis of <i>Jatropha curcas</i> Seeds in Soxhlet Extractor

Biodiesel is an alternative fuel to replace petro diesel with some advantages. One of the methods to produce biodiesel is in-situ transesterification. In this study, in-situ methanolysis of Jatropha curcas seeds in Soxhlet extractor was investigated. Normal hexane was added to enhance the solubility and extractability of methanol in the presence of NaOH as catalyst to Jatropha curcas oil. Response surface methodology based on Box Behnken design was used to determine the optimum reaction conditions. The ratio of mixture volume to seed weight (7.5; 12.5), catalyst concentration (1.75; 2.25 wt.%) and volume ratio of methanol to mixture (0.3; 0.7) were selected as experimental parameters. The biodiesel yield of (91.37 ± 0.57) %, which was insignificantly different with the predicted value, was obtained with the optimum conditions as follows: the ratio of the mixture volume to seed weight of 12.48 (ml/g), 1.75 wt.% of sodium hydroxide concentration, 0.31of the ratio of methanol volume to the mixture volume at 60 °C for 60 min reaction time. The maximum yield of (98.63 ± 2.9) % was achieved at optimum conditions during 3 hours reaction time at 60 °C.

In situ transesterification of coconut oil using mixtures of methanol and tetrahydrofuran

The conventional biodiesel production method requires oil extraction followed by transesterification with methanol. The solubility of vegetable oils in methanol is low which decreases the overall rate of reaction. To eliminate the oil extraction step and improve the overall reaction rate, simultaneous extraction, esterification and transesterification were conducted by directly mixing methanol and tetrahydrofuran (THF) co-solvent and sulfuric acid catalyst with ground, desiccated coconut meat (copra) in a batch process and continuing the reaction until the system reached steady state. After separation of the mixture, yield was obtained by measuring the content of triglycerides, diglycerides and monoglycerides in the biodiesel phase. The yield increases with THF:methanol ratio, methanol:oil molar ratio and temperature. Within the range of conditions tested, the highest yield achieved was 96.7% at 60°C, THF:methanol volume ratio of 0.4 and methanol:oil molar ratio of 60:1. The methanol:oil molar ratio is necessarily high in order to completely wet the copra mass, but is still lower than in previous studies by other researchers on in situ transesterification. Product assays show that the resulting biodiesel product is similar to conventionally produced coconut biodiesel. The results indicate that the in situ transesterification of copra using methanol/THF mixtures merits further study.

Comparison of Intravenous Lipid Emulsion, Bicarbonate, and Tailored Liposomes in Rabbit Clomipramine Toxicity

Liposome (LIP)-like lipid dispersions have emerged as useful detoxification vehicles in vitro. The authors compare resuscitation with tailored LIPs, 20% intravenous lipid emulsion (ILE), and sodium bicarbonate (BIC), in a rabbit model of clomipramine toxicity. Sedated, instrumented New Zealand white rabbits underwent clomipramine infusion at 3.2mg/kg/min to 50% baseline mean arterial pressure (MAP) and then at 1.6mg/kg/min for 30minutes. BIC (3mL/kg 8.4%), ILE (3mL/kg 20%), or LIP (24mg/kg) were infused as rescue treatments at toxicity and were repeated at 10minutes (n=5 in each group). Thirty-minute MAP was greatest in ILE-treated animals: 61mmHg ILE (interquartile range [IQR]= 49 to 64mmHg), 43mmHg LIP (IQR= 36.5 to 49mmHg), and 10mmHg BIC (IQR= 10 to 44mmHg; all p=0.02). Two of the five BIC-treated animals survived to 30minutes, compared with all five of the ILE-treated animals and all five of the LIP-treated animals (p=0.044). Both ILE and LIPs improved hemodynamic recovery compared with bicarbonate in clomipramine-induced cardiotoxicity in rabbits. Greater 30-minute MAP was observed in the ILE group.

Systhesis of double-hydrophilic core-shell type multiarm star copolymer polyethylenimine-block-poly(2-hydroxyethyl methacrylate

Multiarm star block copolymers hyperbranched polyethylenimine-b-poly(2-hydroxyethyl methacrylate) (HPEI-b-PHEMA) with average 28 PHEMA arms have been prepared by atom transfer radical polymerization (ATRP) of HEMA in a mixed solvent of methanol and water using a core-first strategy. The hyperbranched macroinitiator employed was prepared on the basis of well-defined hyperbranched polyethylenimine with Mw/Mn of 1.04 by amidation with 2-bromo-isobutyryl bromide. The polymerization condition was optimized to prepare star copolymers with narrow dispersity, and the variables included the volume ratio of methanol to water, the molar ratio of initiating site to CuCl and the molar ratio of [CuCl]:[CuBr2]. Under the optimized polymerization condition, the lowest Mw/Mn value of the obtained star copolymers was around 1.3. Kinetic analysis showed that an induction period existed in the polymerization of HEMA. After this induction period, a linear dependence of ln([M]0/[M]t) on time was observed. The obtained HPEI-b-PHEMA could adsorb hydrophilic molecules. The comparison with the star copolymer with hydrophobic core and hydrophilic PHEMA shell verified that both the hydrophilic core and shell could host the hydrophilic guests, but the amidated HPEI core was more effective than the PHEMA shell.

Synthesis of a New Perylene Bisimide Dye Containing Melamine Moieties and Construction of Well-defined Nano-fiber

A new perylene diimide dye N,N′-bis[1,3,5-triazine-2,4-bis(dodecylamino)-6-amino]hexyl-3,4,9,10-perylene tetracarboxylic diimide(T-PTCD) was synthesized and characterized.Effect of polarity and volume ratio of solvents on the morphology of aggregates prepared by phase-transfer self-assembly or rapid solvent dispersion were comparatively investigated.Well-defined nano-fiber of T-PTCD was simply fabricated by the phase-transfer crystallization between methanol(as "bad" solvent) and chloroform(as "good" solvent).Low volume ratio of methanol and chloroform facilitates the formation of nano-fiber.When the volume ratio of methanol and chloroform is 1∶ 4,the average diameter of T-PTCD nano-fiber is ca.100 nm and the length is about 10 μm.In addition,the morphology of aggregates prepared by rapid solvent dispersion is significantly inferior to that by phase-transfer self-assembly.

Optimization of biodiesel production process from soybean oil using the sodium potassium tartrate doped zirconia catalyst under Microwave Chemical Reactor

A solid base catalyst was prepared by the sodium potassium tartrate doped zirconia and microwave assisted transesterification of soybean oil was carried out for the production of biodiesel. It was found that the catalyst of 2.0(n(Na)/n(Zr)) and calcined at 600°C showed the optimum activity. The base strength of the catalysts was tested by the Hammett indicator method, and the results showed that the fatty acid methyl ester (FAME) yield was related to their total basicity. The catalyst was also characterized by FTIR, TGA, XRD and TEM. The experimental results showed that a 2.0:1 volume ratio of methanol to oil, 65°C reaction temperature, 30 min reaction time and 10 wt.% catalyst amount gave the highest the yield of biodiesel. Compared to conventional method, the reaction time of the way of microwave assisted transesterification was shorter. The catalyst had longer lifetime and maintained sustained activity after being used for four cycles.

Spherical Polymer Brushes in Solvents of Variable Quality: An Experimental Insight by TEM Imaging

The spherical micelle and vesicle composed of [PW12O40](3-) and poly(styrene-b-4-vinylpyridinium methyl iodide) are regarded as a model system to study spherical polymer brushes (SPBs) in solvents of various quality. The pure repulsions occur for the brush chains in the chloroform solution and chloroform/methanol mixture with a methanol volume ratio of 9.1%, where the grafted polystyrene chains have a relatively extended conformation. Further increase in the methanol concentrations leads to the presence of the intra/inter-brush van der Waals attractions. Transmission electron microscopy studies show that there is a coexistence of isolated and oligomeric SPBs and multi-SPB aggregates (MSAs) with the methanol content from 17% to 23%. Only MSAs are detected with the increasing methanol content. Both the corona and core shrink significantly in the isolated and oligomeric SPBs and MSAs. The full interpenetration of the grafted chains is observed between the cores in the oligomeric SPBs and MSAs.

Facile Deposition of Zirconia Optical Films Based on the Solvothermal Treatment of Zirconyl Nitrate-Water-Methanol System

Zirconia optical films have been facilely deposited based on a modified sol-gel route, which involved solvothermal-treating a mixture of zirconyl nitrate, water, and methanol at 80 °C to produce zirconia-based sols, spin-coating the sols on K9 glass substrates, and then calcining the films at moderate temperatures. The experiments show that, at the proper volume ratio of methanol to water VM/VW (from 40/35 to 70/5), the high deprotonation-condensation reaction rate of the precursor zirconium salt, along with the moderate critical supersaturation level of the reaction medium, give rise to stable and uniform sols comprising particles with mean hydrodynamic diameter of 10-40 nm. This enables rapid deposition of zirconia-based films with a comparatively high refractive index of 1.62 (at 1064 nm). After calcination at 400 °C, the purification and crystallization of film material endow the film with a high refractive index of 1.91 (at 1064 nm).

Synthesis and properties of sodium alginate/Na +rectorite grafted acrylic acid composite superabsorbent via 60Coγ irradiation

Sodium alginate/Na +rectorite-graft-poly acrylic acid (SA/Na +REC-g-PAA) composite superabsorbent was prepared via 60Coγ irradiation in methanol solution and nitrogen protection. The effect of the preparation conditions on graft ratio, graft efficiency and absorption of water were investigated. The structure and morphology were analyzed by IR, XRD, TEM and SEM. The results showed that the optimal condition was that the amount of Na +REC was 2 wt%, the ratio of SA/Na +REC to AA was 10 wt%, total dose was 9.0 kGy and volume ratio of methanol to water was 8:2. SEM showed that it is much easier to obtain porous products through 60Coγ irradiation than chemical initiator. The mechanism of graft copolymerization via 60Coγ irradiation was discussed. The water absorption of the graft copolymer in salt solutions of different ionic strengths was also measured, from which the superabsorbent properties are found to be saline sensitive. Ionic strength markedly decreased the water absorption of the sodium alginate grafted superabsorbent composites.

PREPARASI KARAKTERISTIK BIODIESEL DARI MINYAK KELAPA SAWIT

Biodiesel’s characteristics preparation from palm oil. Using vegetable oils directly as an alternative diesel fuel has presented engine problems. The problems have been attributed to high viscosity of vegetable oil that causes the poor atomization of fuel in the injector system and pruduces uncomplete combustion. Therefore, it is necessary to convert the vegetable oil into ester (metil ester) by tranesterification process to decrease its viscosity. In this research has made biodiesel by reaction of palm oil and methanol using lye (NaOH) as catalyst with operation conditions: constant temperature at 60 o C in atmosferic pressure, palm oil : methanol volume ratio = 5 : 1, amount of NaOH used as catalyst = 3.5 gr, 4.5 gr, 5 gr and 5.5 gr and it takes about one hour time reaction. The ester (metil ester) produced are separated from glycerin and washed until it takes normal pH (6-7) where more amount of catalyst used will decrease the ester (biodiesel) produced. The results show that biodiesels’ properties made by using 3.5 (M3.5) gr, 4.5 gr (M4.5) and 5 (M5.0) gr catalyst close to industrial diesel oil and the other (M5.5) closes to automotive diesel oil, while blending diesel oil with 20 % biodiesel (B20) is able to improve the diesel engine performances.

Self-Assembly of Amphiphilic Perylene−Cyclodextrin Conjugate and Vapor Sensing for Organic Amines

An asymmetric, amphiphilic perylene bisimide derivative 1 was synthesized by grafting permethyl-β-cyclodextrin at one side and an octadecyl chain at the other side. Its aggregation capability and morphology, which attract intense interest, were carefully examined by combination of UV-vis, NMR, and fluorescence spectroscopy, DLS, XRD, TEM, and SEM. By adjusting the volume ratio of water and methanol, we are able to control the morphology, benefiting from the amphiphilicity of 1. Furthermore, the particular resulting aggregates were employed as solid-state fluorescence sensing for organic amines. An improvement of both selectivity and sensitivity is achieved compared to previous publications.

Alumina recovery from spent Bayer liquor by methanol

Decomposition of sodium aluminate solution is the key step for alumina production; however, approximately only 55% alumina yield is obtained by seeded precipitation. So, it is difficult to obtain sodium aluminate solution with high caustic ratio. In this study, a method was explored to recover alumina from spent Bayer liquor by deep decomposition with methanol. A variety of conditions, including reaction temperature, reaction time, methanol amount and seed coefficient were elaborately investigated. The results showed that the appropriate conditions were 1:1 in volume ratio of methanol to spent Bayer liquor, more than 1.0 seed coefficient and in a 40 °C water bath for 24 h. By characterizing through XRD, the crystal products were found to be Al(OH) 3. With this method, the molar ratio of Na 2O to Al 2O 3 of the spent liquor can be increased from about 3.0 to 10.0 due to the recovery of alumina, which is beneficial for the treatment of red mud.

Reversible vesicles based on one and two head supramolecular cyclodextrin amphiphile induced by methanol

Reversible vesicles based on supramolecular inclusion of hydroxypropyl-β-CD (HPβCD) and N, N′-bis(ferrocenylmethylene)-diaminohexane (BFD) were prepared in water and methanol–water mixtures. The inclusion stoichiometry of HPβCD with BFD was in a molar ratio of 2:1, which could be named as ‘two head’ supramolecular amphiphile when the solvent was water. However, the inclusion stoichiometry of HPβCD with BFD would tend to be a molar ratio of 1:1 based on introduction of methanol to the solvent, especially when the volume ratio of methanol and water was more than 1:4, which could be named as ‘one head’ supramolecular amphiphile. The inclusion compounds could switch between ‘one head’ and ‘two head’ conformations by changing the methanol concentration of the solvents. The vesicles were also found to be responsive to the stimulus of external molecules. When the inclusion ability between HPβCD and an external guest was relatively stronger, the vesicles were easily destroyed. Furthermore, the vesicles disappeared after adding an oxidizing agent. NMR was used to confirm the conformation of the mixture of HPβCD and BFD in water. The structure and morphology of the vesicles were characterized by TEM and DLS. The vesicles may be used in smart materials, drug delivery and molecular recognition.

Determination of Three Tanshinones from Radix Salvia Miltiorrhiza by Molecularly Imprinted Solid‐phase Extraction

AbstractA selective molecularly imprinted solid‐phase extraction procedure was developed for the selective separation of tanshinone I, tanshinone IIA, and cryptotanshinone from Radix Salvia Miltiorrhiza samples. Tanshinone IIA imprinted polymers (MIP) synthesized in ethanol‐dodecanol system show high affinity to tanshinone IIA and its structure analogs in aqueous environment and the affinity can be controlled by adjusting the intensity of the eluents. By using 60% water‐40% methanol (volume ratio) and 99.5% methanol‐0.5% trifluoroacetic acid (volume ratio) as washing and eluting solvents, most interferences originating from the salvia matrix were eliminated. The extracts were sufficiently clean enough to be directly injected into HPLC for further chromatographic analysis. Good linearity was obtained from 0.4 to 500.0 mg·L−1 (r2=0.999) with the relative standard deviations less than 4.2%. The mean recoveries of tanshinone IIA in Radix Salvia Miltiorrhiza were more than 85.6% at three different concentrations and the limits of detection were 0.06–0.09 mg·L−1. This method is a viable alternative tool to the existing HPLC methods for analyzing the content of the three tanshinones in Radix Salvia Miltiorrhiza samples.

Improved precipitation of gibbsite from sodium aluminate solution by adding methanol

A new method is explored to improve the precipitation of gibbsite from sodium aluminate solution by adding methanol to the pregnant liquor. The stability of sodium aluminate solution decreases in the presence of methanol, leading to faster crystallisation than the normal seeded precipitation process. The effects of methanol amount, caustic concentration, reaction time and temperature, stirring and feeding mode are systematically investigated. Considering possible industrial application, the optimum conditions are 1:1 volume ratio of methanol to sodium aluminate solution, ~ 170 g/L Na 2O and 1.55:1 caustic to aluminate ratio at 60 °C. The feeding mode and feeding rate have no significant effect on the final yield when moderately stirred. Under these conditions, 70% precipitation can be reached within 24 h, which is about 20% higher than the Bayer seeded precipitation practice of at least 56 h. Characterization of the crystals using XRD, SEM, and PSD shows a typical gibbsite phase composed of super-thin sheets with an average diameter of ~ 90 µm. IR and Raman spectra analyses suggest that added methanol captures water molecules from the aluminate ion hydration sphere thus catalyzing the crystallisation process.

Calcium methoxide as a solid base catalyst for the transesterification of soybean oil to biodiesel with methanol

In this study, physical and chemical characterizations of calcium methoxide were investigated to assess its performance as an excellent solid base catalyst using some instrumental methods, such as BET surface area measurement, scanning electron micrographs and particle size distribution. Then, it was used to catalyze transesterification of soybean oil to biodiesel with methanol. The effects of various factors such as mass ratio of catalyst to oil, reaction temperature and volume ratio of methanol to oil were studied to optimize the reaction conditions. The results showed that calcium methoxide has strong basicity and high catalytic activity as a heterogeneous solid base catalyst and it was obtained a 98% biodiesel yield within 2 h in this reaction. Besides, the recycling experiment results showed it had a long catalyst lifetime and could maintain activity even after being reused for 20 cycles.

Hydrolysis of Magnesium Methoxide. Effects of Toluene on Gel Structure and Gel Chemistry

The hydrolysis of magnesium methoxide in methanol or methanol−toluene solvents with a water-to-methoxide molar ratio of 2 has been studied. The gel obtained from the hydrolysis of magnesium methoxide appears to be polymeric based on the mass fractal dimensions and TEM micrographs. The presence of toluene accelerates the hydrolysis and gelation processes. The fractal dimensions of the wet gels obtained in the absence and in the presence of toluene were 2.22 and 1.80, respectively. Both of these observations indicate that the presence of toluene changes the fractal growth from a reaction-limited to a diffusion-limited growth. In either case, the hydrolysis is only completed partially and produces an intimate gel of MgO−Mg(OH)2−Mg(OH)(OCH3). The N2 BET surface area of the dry gel, obtained with a toluene to methanol volume ratio of 1.60, is 1011 m2/g, which is 1.74 times as large as that of the gel obtained in the absence of toluene.

Speed of Sound Measurements on Zirconyl Soap Solutions in Xylene + Methanol

The speed of sound in solutions of zirconyl soaps (caproate, caprylate, and caprate) in xylene + methanol (volume ratio of 4:1) increases with increasing concentration and chain length of the soap. The isentropic compressibility (ks), apparent molar compressibility (φk), and apparent molar volume (φv) were evaluated, and the results were explained in terms of solute−solvent interactions. It is concluded that the soap molecules do not aggregate appreciably below the critical micellar concentration.

Emission spectra, polarization, and molecular association of 1-and 2-methyl-4-amino-5H-[1]benzopyrano[3,4-c]pyridin-5-one in rigid-glass matrix

The fluorescence and phosphorescence spectra and phosphorescence lifetimes of 1-methyl-4-amino-5H-[1]benzopyrano[3,4-c]pyridin-5-one (1-MBPP) and 2-methyl-4-amino-5H-[1]benzopyrano[3,4-c]pyridin-5-one (2MBPP) have been measured in hydrocarbon and hydroxylic rigid-glass matrix at 77 K. The emission polarization measurements in the ethanol—methanol (volume ratio, 5:1) rigid-glass matrix at 77 K provide evidence that the lowest triplet in the 1- and 2-MBPP molecules is π,π*. The phosphoresescence bands are negatively polarized for these molecules and the coupling scheme appears to be 1 n,π* ▪ 3π,π*. The emission and u.v. absorption spectral measurements in the 3-methylpentane and isopentane—methylcyclohexane (volume ratio 5:1) glass indicate the existence of an associated molecule at low temperature. The fluorescence quantum yields of 1-MBPP and 2-MBPP were also measured at room temperature in hydrocarbon and hydroxylic solvents. The fluorescence quantum yields of these molecules are larger in hydroxylic solvents than in hydrocarbon solvents.