Addition Of Short-chain Alcohols Research Articles

Engineered Geobacillus lipolytic enzymes – Attractive polyesterases that degrade polycaprolactones and simultaneously produce esters

Plastic pollution is one of the biggest environmental problems plaguing the modern world. Polyester-based plastics contribute significantly to this ecological safety concern. In this study, lipolytic biocatalysts GD-95RM and GDEst-lip developed based on lipase/esterase produced by Geobacillus sp. 95 strain were applied for the degradation of polycaprolactone films (Mn 45.000 (PCL45000) and Mn 80.000 (PCL80000)). The degradation efficiency was significantly enhanced by the addition of short chain alcohols. Lipase GD-95RM (1 mg) can depolymerize 264.0 mg and 280.7 mg of PCL45000 and PCL80000, films respectively, in a 24 h period at 30 °C, while the fused enzyme GDEst-lip (1 mg) is capable of degrading 145.5 mg PCL45000 and 134.0 mg of PCL80000 films in 24 h. The addition of ethanol (25 %) improves the degradation efficiency ~2.5 fold in the case of GD-95RM. In the case of GDEst-lip, 50 % methanol was found to be the optimal alcohol solution and the degradation efficiency was increased by ~3.25 times. The addition of alcohols not only increased degradation speeds but also allowed for simultaneous synthesis of industrially valuable 6-hydroxyhexonic acid esters. The suggested system is an attractive approach for removing of plastic waste and supports the principles of bioeconomics.

A comparative study on alcohol-diesel blended fuels in a common rail diesel engine: Combined effects of carbon numbers, oxygen content, and molecular structure

Abundant alcohols, including ethanol, propanol, butanol, and pentanol, are expected to be used in compression ignition engines to ease the shortages of fossil fuel. The various alcohols have quite a different combustion and emission characteristics in the engine due to the changes in molecular structures. In this paper, a series of experiments were conducted on a modified common-rail diesel engine fueled with diesel/alcohols blended fuels in a wide operating range. The effects of alcohol chain length, oxygen content, and molecular structure on engine combustion and emission characteristics are studied systematically. The experimental results show that the blending of alcohols increases the peak values of in-cylinder pressure and maximum pressure rising rate. Besides, the combustion duration and ignition delay are mainly affected by oxygen content and isomer structure. The addition of short-chain alcohols will significantly reduce the total mass of particulate matter (PM) emissions, while the CO and HC emissions increase appropriately. The CO, HC, aldehydes, and ethylene emissions are mainly affected by carbon chain length and isomer structure. For PM emissions, the carbon chain length, molecular structure, and oxygen content of alcohol fuels have different influences on PM number, PM mass, and particle size distributions. The shorter carbon chain of alcohol leads to smaller particle size, and higher oxygen content leads to lower total particle mass.

Interfacial and micellization behavior of binary mixture of amino sulfonate amphoteric surfactant and octadecyltrimethyl ammonium bromide: Effect of short chain alcohol and its chain length

The interfacial and micellization behavior of binary mixture of an amino sulfonate amphoteric 3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate (C12AS) and a cationic octadecyltrimethyl ammonium bromide (OTAB) were investigated in aqueous solution without or with a 70 g/L alcohol (including methanol, ethanol, 1-propanol and 1-butanol) at 313.15 K by both the tensiometry and the conductometry. The surface excess concentration, the minimum area per surfactant molecule at the saturated interface and the standard free energy of adsorption at the air-liquid interface were adopted to be characteristic of the interfacial adsorption monolayer. Based on the pseudophase separation model and the regular solution theory, the Clint’s model and the Rubingh’s model was used to obtain the related parameters including the interaction parameters between two surfactant molecules, the compositions and the activity coefficients in mixed micelle and thermodynamic parameters. The effect of the alcohol chain length on the interfacial adsorption and the mixed micellization was discussed. The addition of short chain alcohol influences the properties of mixed cosolvent, the conformation of C12AS molecule and the electrostatic interaction between two surfactant molecules. Thermodynamic data shows that the presence of alcohol with a longer chain is beneficial to form the adsorption monolayer and the mixed micelle, and also it depresses the contribution of entropy to the process of micellization. These findings help with understanding the mechanism on the effect of short chain alcohol on the interfacial and micellization behavior of binary surfactant mixtures and further designing the surfactant formulations.

Insights in the biocatalyzed hydrolysis, esterification and transesterification of waste cooking oil with a vegetable lipase

The present contribution investigates the biocatalytic performance of the lipase obtained from the latex of the native plant known as Araujia sericifera (ASL) in the hydrolysis followed by the esterification of released free fatty acids and transesterification of glycerides of sunflower waste cooking oil WCO. A specific enzymatic activity of 719.05 μmol mg−1 h−1 (60 % conversion of triglycerides towards free fatty acids) was obtained in the hydrolysis of WCO with 0.05 % of biocatalyst (typically, 10.0 g WCO and 5.0 mg of enzyme) and 50 % w/w of water added in 30 min of reaction at 25 °C in homogeneous type of reaction system. The lipase has the capacity to catalyze the hydrolysis of the triglycerides mainly towards monoglycerides and diglycerides in a lesser extent. The released FFAs and the remaining glycerides reacted in tandem by addition of short chain alcohols immediately after the hydrolysis (without addition of more enzyme to the reaction media). Above 90 % conversion of the FFAs was obtained with methanol, ethanol, n-propanol and n-butanol at contents as low as 1:0.2 oil: alcohol molar ratio at 25 °C. The transesterification of the remaining monoglycerides (about 20 %) was also observed although no further reaction of the triglycerides was detected even under a great excess of alcohol.

Amyloid formation of bovine insulin is retarded in moderately acidic pH and by addition of short-chain alcohols

Protein aggregation and amyloid formation are associated with multiple human diseases, but are also a problem in protein production. Understanding how aggregation can be modulated is therefore of importance in both medical and industrial contexts. We have used bovine insulin as a model protein to explore how amyloid formation is affected by buffer pH and by the addition of short-chain alcohols. We find that bovine insulin forms amyloid fibrils, albeit with different rates and resulting fibril morphologies, across a wide pH range (2–7). At pH 4.0, bovine insulin displayed relatively low aggregation propensity in combination with high solubility; this condition was therefore chosen as basis for further exploration of how bovine insulin’s native state can be stabilized in the presence of short-chain alcohols that are relevant because of their common use as eluents in industrial-scale chromatography purification. We found that ethanol and isopropanol are efficient modulators of bovine insulin aggregation, providing a three to four times retardation of the aggregation kinetics at 30–35% (vol/vol) concentration; we attribute this to the formation of oligomers, which we detected by AFM. We discuss this effect in terms of reduced solvent polarity and show, by circular dichroism recordings, that a concomitant change in α-helical packing of the insulin monomer occurs in ethanol. Our results extend current knowledge of how insulin aggregates, and may, although bovine insulin serves as a simplistic model, provide insights into how buffers and additives can be fine-tuned in industrial production of proteins in general and pharmaceutical insulin in particular.

Shift in membrane miscibility transition temperature upon addition of short-chain alcohols.

I consider the effect of a small concentration of a molecule, such as a short-chain alcohol, on the miscibility transition temperature of a giant plasma membrane vesicle. For concentrations sufficiently small such that the system can be treated as a dilute solution, the change in transition temperature is known to depend upon the extent of the molecule's partition into the coexisting liquid-disordered and liquid-ordered phases. Preferential partitioning into the former decreases the miscibility temperature, while preferential partitioning into the latter causes an increase. The analysis, combined with calculated values of the partition coefficient of saturated chains, illuminates the results of recent experiments on the change in miscibility transition temperatures with changing alcohol chain length, and makes several testable predictions.

Interactions between Water-soluble Dye and Cationic Surfactant and Effects of Added Alcohol

In water-soluble dye, possessing -SO3- groups and the cationic surfactant (DTAB or CTAB) system, phase separation with precipitation and redissolution of precipitation were observed to result from cooperative-way between the dye and surfactant. On adding cationic surfactant to the dye aqueous solution, insoluble sedimentation occured. With further increase in cationic surfactant, precipitation was completely redissolved in aqueous solution. Flocculation was due to the electrostatic interaction between the dye and cationic surfactant and a hydrophobic layer would be formed on the dye since the tails of surfactant were facing the water phase. Redissolution was the cause for adsorption of cationic surfactant as micelles on the dye.Redissolved solution in dye/DTAB or CTAB/water systems showed high viscosity. The addition of short-chain alcohol (1-propanol) lead to lower viscosity and prevention of aggregation. Surface tension, electro-conductivity and static light scattering measurements clearly indicated 1-propanol to be essential to interactions between the surfactant and dye.

Effect of 1-alcohols on micelle formation and protein folding

The effect of monohydric alcohols on the micellization of sodium dodecyl sulphate (SDS) and on the thermal unfolding of lysozyme has been studied by DSC as a function of alcohol concentration in the water-rich region of composition. The results show that the effects due to alcohols on these very different systems and processes are strikingly similar and are closely linked with structural and dynamical properties of water–alcohol mixtures themselves. The data have been interpreted on the basis of the assumption that the addition of short chain alcohol affects both the thermal unfolding of proteins as the micellization process modifying the extent of enthalpy and entropy contribution associated with structural reorganization of water in these processes.

Effect of Aqueous Alcohol Solutions on the Thermal Transition of Lysozyme: A Calorimetric Study

Thermal denaturation of lysozyme has been studied at pH = 3 in water/ethanol and water/tert-butyl alcohol mixtures in the water rich region of composition (mole fraction of cosolvent x2 < 0.12) by high-sensitivity differential scanning calorimetry. The results show that on increasing alcohol concentration, the enthalpy and entropy of denaturation of lysozyme first reach a maximum at an intermediate composition x2 = typical for each alcohol ( ≅ 0.06 for ethanol and ≅ 0.02 for tert-butyl alcohol) and then decrease with increasing x2. In addition, two enthalpy−entropy compensation patterns each having its own compensation temperature (Tc) clearly appear from the data: a compensation data line obtained with rising x2 in the 0− range (with Tc = 281 ± 6 K) followed by a compensation line with Tc = 403 ± 14 K after x2 passes the value. The value of is close to that at which a change in the nature of solvent component interaction occurs as inferred from compressibility and IR absorption measurements. The data have been interpreted on the basis of the assumption that the addition of short chain alcohols affects the thermal transition of proteins, modifying the extent of enthalpy and entropy contribution associated with structural reorganization of water in the unfolding process.

Small-angle neutron scattering studies of microemulsions stabilised by aerosol-OT. Part 3.—The effect of additives on phase stability and droplet structure

The droplet structure of water-in-oil microemulsions formed with the surfactant AOT in various hydrocarbon solvents has been studied by small-angle neutron scattering (SANS). As the temperature of the single-phase microemulsion is raised towards that at which a phase transition occurs, an increased scattering at low Q, characteristic of critical scattering, is exhibited, which is a result of the attractive interactions between the droplets. The effect on the microemulsion of small quantities of additives (toluene, octan-1-ol and benzyl alcohol) has been investigated for the n-alkane solvents heptane, decane, undecane and dodecane. Both a systematic increase or decrease in the transition temperature and a corresponding change in the magnitude of the critical scattering component of the SANS intensity profile are observed, which depend on the nature of the additive. These results are coupled to a change in the water droplet radius, consistent with a model in which amphiphilic molecules such as benzyl alcohol and octanol are preferentially adsorbed into the water–surfactant interfacial region, whereas toluene remains predominantly in the bulk hydrocarbon phase and probably does not come into contact with the aqueous core of the droplet. The droplet radius and the phase stability of the microemulsion are also affected by addition of short-chain alcohols and show a systematic variation as the chain length is increased. These changes have been interpreted in terms of the partitioning of alcohols between the water core and the interface and their effect on the surfactant shell.

Calorimetric determination of the enthalpy of micelle formation in aqueous media

The enthalpy of micelle formation of ionic surfactants in aqueous solutions with varying concentration of additives (i. e. NaCl. alcohols) was measured by using a very sensitive microcalorimeter. The heats of dilution were measured from concentrations below the c.m.c. to above c.m.c. This enables one to detect the aggregation process around the c.m.c. region, an analysis hitherto not extensively reported in the current literature. The effect of electrolyte addition on micellar enthalpy is discussed, as compared to the addition of short chain alcohols.

ChemInform Abstract: EFFECT OF ALCOHOLS ON THE MICELLE FORMATION OF NONIONIC SURFACTANTS IN AQUEOUS SOLUTIONS

The variation of critical micelle concentrations (CMC) of polyoxyethylene lauryl ethers having various ethylene oxide chain lengths \barn(\barn=6, 11, 20, and 31) on addition of short chain alcohols to the surfactant aqueous solutions was determined at 20 °C. Thermodynamic quantities of micelle formation in methanol– and ethanol–water mixtures and in pure water were obtained in connection with the heat of micelle formation determined by direct calorimetry. Methanol and ethanol showed a CMC-increasing effect only, whereas the addition of n-propanol, n-butanol, and n-pentanol showed a CMC-decreasing effect. The overall CMC-increasing effect is interpreted as being mainly due to the fact that methanol and ethanol weaken the hydrophobic bond. However, the effect also has a secondary effect of lowering the CMC slightly on the polyoxyethylene portion of a surfactant. Several factors are suggested for explaining this secondary effect. The CMC-decreasing effect is explained by a decrease in the free energy of mix...

Effect of Alcohols on the Micelle Formation of Nonionic Surfactants in Aqueous Solutions

Abstract The variation of critical micelle concentrations (CMC) of polyoxyethylene lauryl ethers having various ethylene oxide chain lengths \barn(\barn=6, 11, 20, and 31) on addition of short chain alcohols to the surfactant aqueous solutions was determined at 20 °C. Thermodynamic quantities of micelle formation in methanol– and ethanol–water mixtures and in pure water were obtained in connection with the heat of micelle formation determined by direct calorimetry. Methanol and ethanol showed a CMC-increasing effect only, whereas the addition of n-propanol, n-butanol, and n-pentanol showed a CMC-decreasing effect. The overall CMC-increasing effect is interpreted as being mainly due to the fact that methanol and ethanol weaken the hydrophobic bond. However, the effect also has a secondary effect of lowering the CMC slightly on the polyoxyethylene portion of a surfactant. Several factors are suggested for explaining this secondary effect. The CMC-decreasing effect is explained by a decrease in the free energy of mixing resulting from the solubilization of alcohol molecules into the micelle.