Acetic Acid Water Solution Research Articles

Spectral, structural, and thermodynamic properties of acetic acid–water solutions at different temperatures: A complete guideline for understanding bonding and structure of binary solutions

Spectral, structural, and thermodynamic properties of acetic acid–water solutions at different temperatures: A complete guideline for understanding bonding and structure of binary solutions

PEROXIDE CELLULOSE FROM WHEAT STRAW

The stalks of wheat straw (triticum sh,), stored up in Еmеlyanovsk region of the Krasnoyarsk hand edge in the form of segment in 2–3 cm treated by the water solution of hydrogen peroxide and acetic acid with the catalytic amount of the sulfuric acid under hydromodule 6. The acetic acid is oxidated to peracetic acid, which, in turn, oxidizes lignin with forming of the dissolved products. The variable technological factors and ranges of their variation: initial concentration of the acetic acid (4–8-mol/l), hydrogen peroxide (3–5-mol/l); the sulfuric acid (0.25–0.65 mass.%); the temperature (80–90 °C) and cooking duration (240–330 min). The dependencies of the dissolved lignin part, output and whiteness of the cellulose from variable factor aproximated by the regression equations of the second order. The equations used for graphic presentation results and calculation of the optimum conditions of the process. On the leading indexes (output 49–63%, whiteness before 89%, explosive length before 8700 m, forcing through resistance before 240 кPа, tear resistance 420 mN) peroxide cellulose from wheat straw with the degree of the grind 30 °ShR does not concession by specified characteristic of the sulphate unbleached cellulose from hard wood. The possibility of the cellulose reception with high whiteness after cooking will allow in the row account to refuse from high-priced following bleaching.

Continuous recovery of high-purity Kraft lignin from black liquor via simultaneous, liquid-phase acidification and purification

A key advantage of the Sequential Liquid-Lignin Recovery and Purification (SLRP) process for the recovery of lignin from Kraft black liquor is the precipitation of a solvated, “liquid-lignin” phase (vs. the typical solid) during the CO2 acidification step. Here, we have discovered that this lignin can also be maintained in a solvated state during the H2SO4 acidification step if aqueous acetic acid from the Aqueous Lignin Purification with Hot Agents (ALPHA) process is incorporated into the H2SO4 solution. As the liquid-lignin is converted from its salt form at pH = 9.5 to its acid form at pH = 2.5, the lignin initially solvated with water becomes solvated and thus liquefied with the acetic acid–water solution. Maintaining the lignin in a solvated liquid state has two advantages: (1) the entire SLRP + ALPHA process, from starting black liquor to final lignin product, can be operated continuously; and (2) mass transfer of metals impurities out of the liquid-lignin phase is significantly enhanced, resulting in both a cleaner Kraft lignin product (∼2000 ppm Na and 0.5–1.0% ash) and reduced water washing.

Supercritical CO2 assisted strategy for acetic acid elimination from industrial cellulose acetate–water mixtures

A critical analysis of the major steps involved in the cellulose acetate industrial process is performed, with the aim of proposing possible improvements using supercritical CO2 based sub-processes. Once highlighted the main weakness of the traditional process, related to the (i) fine modulation of the acetylation reaction to obtain 2.5 acetate, (ii) acetic acid removal from the acetic dope, and (iii) treatment of the diluted acetic acid–water solution, the most attractive alternative resulted the adoption of a supercritical antisolvent extraction (SAE) performed on the acetic dope. Operating in this way, the problems related to the use of large quantities of water to remove acetic acid from the acetic dope are resolved, since it will be directly extracted by supercritical CO2. Micro- and nanoparticles, or filaments, of cellulose acetate can be produced. Finally, an acetic acid residue of 23 ppm, in the supercritical CO2 treated cellulose acetate, confirmed the success of this alternative process configuration.

One-pot Synthesis of Ag–TiO2–Sepiolite Nanocomposites with Excellent Antibacterial Activity

A novel Ag–TiO2-sepiolite antibacterial nanocomposite was prepared by a one-pot solvothermal method in acetic acid–water solution. The ternary nanostructures consist of Ag-decorated TiO2 nanoparticles (NPs) supported with sepiolite nanofibers. Sepiolite served as a template for reducing the agglomeration of TiO2 NPs and improving the interface reactions between the nanocomposite and bacteria cells. Ag NPs were introduced to enhance the absorption of visible light, and suppress the recombination of electron–hole pair. The synergistic effects of TiO2, Ag NPs and sepiolite nanofibers led to the superior antibacterial activity of the Ag–TiO2-sepiolite nanocomposite against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus.

NiCuMo-SiO2 catalyst for pyrolysis oil upgrading: Model acidic treatment study

The main reasons of catalysts deactivation in hydro-processing pyrolysis liquids are by coke deposition, poisoning by bio-oil impurities (S, N, K, Cl, etc.), leaching of catalyst components, structural degradation in the presence of H2O, and sintering. The deactivation of catalysts by the acidity of the pyrolysis liquid is a specific concern, and this deactivation mechanism was studied by treating newly developed NiCuMo-SiO2 catalysts in 1 M acetic acid water solution (pH = 2–3). The activity of the acid-treated catalysts was subsequently investigated in the hydrodeoxygenation of gaseous propionic acid, in a tubular reactor at 225 °C with n-hexane and n-octane serving as diluent and internal standard, respectively.The samples treated by acid at different times (15–360 min) were characterized by X-ray diffraction (XRD), high resolution transition electron microscopy (HRTEM), X-ray fluorescence (XRF), CO chemisorption, N2 physical adsorption, and X-ray photoelectron spectroscopy (XPS). XRF and HRTEM studies together with the residual mass of catalyst pointed out at gradual leaching of catalyst components. Among the catalyst components, dissolution of nickel was the most pronounced, while molybdenum content decreased to a lesser extent. This is due to the formation of more acid stable molybdenum blues. The amount of copper decreased only slightly, due its higher electrochemical potential. Oxidation of metalliс species Cu and Ni is shown to obtain Cu2O, NiO and Ni(OH)2-like phases. Interestingly, the acidic treatment resulted in increasing active surface of the catalyst, nevertheless, the catalyst activity in propionic acid conversion irreversibly decreased in time by the acetic acid treatment due to loss of the active components (substantially nickel).

Frying influence on virgin olive oils by monitoring change of aliphatic monoaldehydes

When virgin olive oil (VOO) have been fried long time at high temperature, some aliphatic monoaldehydes including hexanal, heptanal, octaldehyde, nonanal and decanal were found in fried VOO and food samples. The HPLC method has been developed for determination of aliphatic monoaldehydes in VOO and food samples after different fried conditions. These five aliphatic monoaldehydes could be separated and analyzed in 60 min on reversed phase ODS column with methanol/0.1% acetic acid water solution mobile phase at 1.0 mL min-1 flow rate, after being derivatized with 2,4-dinitrophenylhydrazine (DNPH). The method was validated with recovery results ranging from 86% to 114%. Calibration plots of aliphatic aldehydes were linear (r≥0.9991) in the concentration range from 1.0×10-6 to 1.5×10-4 mol L-1. The LODs were between 6.5×10-8 and 3.98×10-7 mol L-1. The proposed method provides a reliable and sensitive quantitative evaluation for aliphatic monoaldehydes in fried oils and fried potatoes samples. The experiments results verify that the VOOs are not suitable to be fried long time at high temperature. The frying time should be less than 3.0 min, and the frying temperature should be below 150 °C for the healthy diet.

Effects of binary solvent mixtures on the electrospinning behavior of poly (vinyl alcohol)

Different concentrations of PVA solutions were prepared and electrospun from water, ethanol-water and acetic acid-water binary solvent mixtures to study the effects of binary solvent mixtures. The solubility and spinnability of the prepared PVA solutions were discussed using Teas graph. The viscosity of the PVA solutions increased with the increase of PVA concentration. After electrospinning, fibers with an average diameter in the range of 70–300 nm were observed for the fibers spun from acetic acid-water binary solvent mixtures and in the range of 500–1000 nm for the fibers spun from ethanol-water binary solvent mixtures. Circular fibers at lower PVA concentration and flat fibers at higher PVA concentration were observed for the fibers spun from acetic acid-water solutions. Flat fibers were found in case of all the fibers irrespective of PVA concentrations spun from of ethanol-water binary solvent mixtures. Fiber diameters showed an inverse relationship with respect to the electrical conductivity of the solutions, regardless of the solvents. Fiber mats spun from acetic acid-water binary solvent mixtures exhibited nearly double the tensile strength than those of ethanol-water binary solvent mixtures. Differential scanning calorimetry (DSC) analysis of the electrospun fiber mats showed no effect of solvents on thermal properties.

Corrosion resistance of WC–Co and WC–Ni type sintered carbides in acetic acid water solution

Corrosion resistance of sintered WC carbides products is an important factor determining their service properties. As an alternative to cobalt binders mainly nickel based matrices are introduced to increase corrosion resistance. To assess the effect of the metallic binder and carbide grain size on electrochemical corrosion susceptibility two grades with conventional cobalt matrices and two sinters with nickel were investigated. The gravimetric (weight) as well as electrochemical (potentiodynamic, potentiostatic, and galvanostatic) measurements in a 10% water solution of acetic acid were performed. The cobalt samples were characterized by lower corrosion resistance in comparison with the nickel containing grades. In most cases the investigated samples revealed a tendency to self‐passivation, the phenomena being more intense in the nickel sinters. Both electrochemical and gravimetric measurements showed that the increased fraction of the metallic phase and microstructural inhomogeneity lowered the corrosion resistance. The variation in grain size in <1 μm ÷ 3 μm interval did not significantly affect the corrosion intensity.

Benign Fractionation of Lignin with CO2-Expanded Solvents of Acetic Acid + Water

Kraft lignin was fractionated by molecular weight (MW), using CO2-expanded solutions of acetic acid/water in a 90/10 wt/wt ratio. In particular, as CO2 pressures were increased from 7 bar to 48 bar, expanding the liquid-solvent phase and reducing its dielectric strength, lignin fractions decreasing in MW from 15 000 to 1250, with polydispersity index (PDI) values decreasing from 3.7 to 1.6, were obtained. The recovered lignin fractions were similar, in terms of chemical functionality. With the use of gas-expanded liquids (GXL), only one solvent composition is required, and recovery and reuse of the biorenewable CO2 + acetic acid–water solution is facilitated through pressure release and recompression. The process was demonstrated for the recovery of seven lignin fractions to demonstrate its versatility and effectiveness, but simpler operation with recovery of just a low MW lignin fraction and a high MW lignin fraction is more consistent with anticipated applications.

Migration of DEHP from plastic to food simulants under microwave heating

The migration of plasticizer DEHP from the plastic products (4 kinds of commonly used plastic food containers under microwave heating: plastic wrap, food bags, ordinary plastic boxes, microwave special plastic boxes) through food contact materials to food simulants (isooctane, 10% ethanol-water solution (v/v), 3% acetic acid-water solution (w/w) and distilled water) was studied under microwave heating (power levels of 400 W). The results shows that the DEHP mobility increases with the increase of microwave heating time, DEHP mobility in isooctane and 3% acetic acid-water solution (w/w) is significantly greater than in 10% ethanol-water solution (v/v) and distilled water; the order of DEHP mobility in isooctane is plastic wrap>food bag>common plastic box>microwave-safe plastic box, while in 3% acetic acid (w/w), the order is food bag>common plastic box>microwave-safe plastic box>plastic wrap.

Chitosan Nanoparticle Penetration into Shrimp Muscle and its Effects on the Microbial Quality

Chitosan (CH) and chitosan-sodium tripolyphosphate (CH-TPP) solutions were produced with and without sonication and ultra-shearing. The CH and CH-TPP particles and solutions were evaluated for physicochemical properties, and fluorescently labeled particle penetration into shrimp muscle tissue through vacuum tumbling was observed. Two solutions were prepared: (1) a 0.5 % CH solution in 1 % acetic acid and (2) a CH-TPP solution, prepared by adding 0.167 % sodium tripolyphosphate to the CH solution, instantly forming CH-TPP nanoparticles through ionotropic gelation. Untreated shrimp meat and shrimp meat vacuum tumbled with CH, CH-TPP, acetic acid, sodium tripolyphosphate, and distilled water solutions were analyzed for aerobic plate counts for 24 days of refrigerated storage at 4 °C. Processing with sonication and ultra-shearing reduced the particle sizes of CH and CH-TPP nanoparticles and the molecular weight of CH. It was observed that after processing, fluorescently labeled CH and CH-TPP nanoparticles could penetrate inside of and attach to shrimp muscle tissues through vacuum tumbling. At 24 days of refrigerated storage, shrimp vacuum tumbled with processed CH solution had the lowest aerobic plate counts of all treatments and it was the only treatment to have unchanged microbial quality throughout the entire storage time. Vacuum tumbling with sonicated and ultra-sheared CH solution enhanced particle penetration into shrimp and inhibited microbial growth during refrigerated storage.

Preparation of paclitaxel/chitosan co-assembled core-shell nanofibers for drug-eluting stent

The paclitaxel/chitosan (PTX/CS) core-shell nanofibers (NFs) are easily prepared by co-assembly of PTX and CS and used in drug-eluting stent. The mixture solution of PTX (dissolved in ethanol) and CS (dissolved in 1% acetic acid water solution) under sonication will make the formation of NFs, in which small molecule PTX co-assembles with biomacromolecular CS through non-covalent interactions. The obtained NFs are tens to hundreds nanometers in diameter and millimeter level in length. Furthermore, the structure of PTX/CS NFs was characterized by confocal laser scanning microscopy (CLSM), zeta potential, X-ray photoelectron spectroscopy (XPS) and nanoscale infra-red (nanoIR), which provided evidences demonstrated that PTX/CS NFs are core-shell structures. The ‘shell’ of CS wrapped outside of the NFs, while PTX is located in the core. Thus it resulted in high drug loading content (>40wt.%). The well-controlled drug release, low cytotoxicity and good haemocompatibility were also found in drug carrier system of PTX/CS NFs. In addition, the hydrophilic and flexible properties of NFs make them easily coating and filming on stent to prepare drug-eluting stent (DES). Therefore, this study provides a convenient method to prepare high PTX loaded NFs, which is a promising nano-drug carrier used for DES and other biomedical applications. The possible molecular mechanism of PTX and CS co-assembly and core-shell nanofiber formation is also explored. Statement of significanceWe develop a convenient and efficient approach to fabricate core-shell nanofibers (NFs) through the co-assembly of paclitaxel (PTX) and chitosan (CS). Results indicate that the co-assembled PTX/CS NFs have high drug loading content (>40wt.%), low cytotoxicity, well-sustained drug release and good haemocompatibility. The PTX/CS NFs coated easily on stents with substrate surface uneven and irregular. Findings from this work provide a novel drug/polymer system, which would have potential application for drug-eluting stent (DES).

Preparation of pure chitosan film using ternary solvents and its super absorbency

Chemical modification and graft copolymerization were commonly adopted to prepare super absorbent materials. However, physical microstructure of pure chitosan film was optimized to improve the water uptake capacity in this study. Chitosan films with micro-nanostructure were prepared by a ternary solvent system. The optimal process parameters are 1% acetic acid water solution: dioxane: dimethyl sulfoxide=90: 2.5: 7.5 (v/v/v) with chitosan concentration at 1.25% (w/v). The water uptake capacity of the chitosan film prepared under the optimal process parameters was 896g/g. The prepared chitosan films also exhibited high water uptake capacity in response to external stimuli such as temperature, pH and salt. This finding may provide another way for improving the water absorbency. The pure chitosan film may find potential applications especially in the fields of hygienic products and biomedicine due to its super water absorbency and nontoxicity.

BIOMIMETIC TCF BLEACHING OF PULP BY SIMPLE INORGANIC COMPLEXES OF CUPRIC/COBALT ACETATE

Oxygen delignified kraft pulp from eucalyptus (E. urophylla × E. grandis) was catalytically pretreated in aerobic condition using ammonium persulfate in present of catalists like cupric acetate and/or cobalt acetate in acetic acid-water solution, i. e. S2O8 2- -Cu 2+ , S2O8 2- -Co 2+ and S2O8 2- -(Cu 2+ +Co 2+ ). Final bleached pulp after pretreatment with the three catalytic systems showed higher delignification (23.45%, 21.85% and 19.63% respectively), better optical properties (82.93, 82.18 and 81.92% ISO brightness respectively) and pulp viscosity (787, 791 and 762 mL/g respectively; mL/g: intrinsic viscosity unit of pulp) than the control pulp (14.12% delignification, 77.33% ISO brightness and 746 mL/g viscosity). S2O8 2- -Cu 2+ and S2O8 2- -Co 2+ showed similar reduction in hydrogen peroxide consumption (61.91%, 62.48%), and S2O8 2- -(Cu 2+ +Co 2+ ) showed a greater reduction in hydrogen peroxide consumption than the two treatments (83.05%). Some improvements in tensile and tear strength of the resulting pulp were observed. The new sequence also yields composite effluents with larger percentage of lignin aromatic compounds compared to the control.

Simultaneous determination of Gastrodin and eight nucleosides and nucleobases in Tibet cultured Gastrodia elata by HPLC method

This study aims to establish an HPLC method for simultaneous determination of gastrodin and eight nucleosides and nucleobases components in Gastrodia elata. The separation was carried out on an Agilent Zorbax Bonus-RP (4.6 mm x 250 mm, 5 μm) column with a methanol-(0.04% acetic acid) water solution gradient elution program at a flow rate of 1.0 mL x min(-1). The column temperature was 36 degrees C, and the detection wavelength was 254 nm. The volume of injection was 20 μL. The nine components including gastrodin, cytosine, uracil, cytosine, adenine, thymine, uridine, guanosine and adenosine were well separated. The calibration curve was well linear in the range of 2.04-262.00 mg x L(-1), 0.20-24.67 mg x L(-1), 0.18-23.75 mg x L(-1), 0.20-25.83 mg x L(-1), 0.20-26.67 mg x L(-1), 0.16-20.00 mg x L(-1), 0.22-27.71 mg x L(-1), 0.20-24.29 mg x L(-1), 0.24-30.58 mg x L(-1), respectively, and the correlation coefficient was between 0.998 9-0.999 9. The average recovery of gastrodin and eight nucleosides and nucleobases were 96.4%-99.6%, RSD less than 2.7% (n = 6). The contents of gastrodin in all the seven Tibet cultured Gastrodia elata samples were over 2 mg x g(-1). Further, all samples contain higher contents of adenosine, guanosine, uridine and cytidine compared to low contents of cytosine, uracil, adenine and thymine. The established method is accurate, reproducible and suitable for the determination of gastrodin and eight nucleosides and nucleobases comppnents in Gastrodia elata.

Determination of some B Vitamins in Sour Cherry Juice Using Dispersive Liquid-liquid Microextraction Followed by High-performance Liquid Chromatography.

Dispersive liquid-liquid microextraction method (DLLME) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was used to determine thiamine (B1), nicotinamide (B3) and pyridoxine (B6) in sour cherry juice. This method was rapid, simple and sensitive. Separation was accomplished using a C18 column. The optimum chromatographic conditions were found to be: mobile phase consisted of 8% methanol and 92% aqueous phase (1% (V/V) acetic acid water solution); flow rate, 0.7 mL/min; detection wavelength, 260 nm and pH, 3.3. The extraction efficiency of thiamine, nicotinamide and pyridoxine was influenced by factors such as: additional salt effect, the kind and volume of disperser and extraction solvents. In this research, the limit of detection (LOD) and quantification (LOQ) were 0.9 and 3 ng/mL for thiamine, 1.5 and 5 ng/mL for nicotinamide, 0.9 and 3 ng/mL for pyridoxine. The relative standard deviations (RSDs) were less than 2.87% (n=3). An appropriate linear behavior over the observed concentration range was obtained with the value of R²>0.996 for the target vitamins. This method was successfully applied to the sour cherry juice samples. Sour cherry var. Gise (Prunus cerasus var. Gise), which was used in this research, was a local variety of the sour cherry with large stone, double flowers, double fruits, dark red skin and dark red juice. This variety was identified in high altitude areas of Isfahan province after five years of study, since 2005, by Agricultural and Natural Resources Research Center of Isfahan.

Pharmacokinetic study of two docetaxel preparations in Beagle dogs by a LC‐MS/MS method (1064.5)

Pharmacokinetic study of two docetaxel preparations in Beagle dogs by a LC‐MS/MS method Xin Huang, Guanlan Liu, Zhenzhou Jiang and Luyong Zhang Jiangsu Center for Drug Screening, China Pharmaceutical University, Nanjing 210009, China Objective: To establish a LC‐MS/MS method for determination of docetaxel in dog plasma and compare the PK profiles of two preparations in Beagle dogs. Methods: 12 dogs were divided into two groups and i.v. administrated test and reference preparations, respectively. Plasma samples were collected at different time points. The analytes were separated through a C18 column with a mobile phase of methanol‐0.1% acetic acid water solution (85:15, v/v), and analyzed by ESI in SRM mode. The ions were m/z 830.4→303.9 and 876.4→591.3 for docetaxel and paclitaxel(IS), respectively. The pharmacokinetic parameters were calculated by DAS 2.0 software. Results: The calibration curves were linear over the ranged 3‐2000 ng/mL (r=0.9980) with the LLOQ 3 ng/mL. The within‐ and between‐batch precisions were within 8%, and the accuracy ranged from 94 to 110%. The overall recovery for docetaxel was about 91.3%. The main PK parameters t1/2, Cmax, MRT0‐24 and AUC0‐24 for test and reference preparations were: 7.3±2.0 h and 7.2±2.5 h, 796.1±321.8 ng/mL and 1248.0±178.6 ng/mL, 6.2±1.1 h and 5.3±0.8 h,948.4±100.2 ng·h/mL and 969.7±322.1 ng·h/mL. Conclusion: The method developed is sensitive, specific, rapid, and reproducible. It is suitable for PK studies of docetaxel in dogs. The results above shows no significant differences (P>0.05) between the two preparation in PK parameters in dogs.

Investigation of Acetic Acid Hydration Shell Formation through Raman Spectra Line-Shape Analysis

Raman spectra of acetic acid aqueous solutions in the 500-4000 cm(-1) range have been measured as a function of water concentration to investigate the hydration shell formation mechanism around the acetic acid molecules. A fitting procedure based on the Kubo-Anderson model has been applied to the spectra. This has allowed us to determine the average lifetime of the hydrogen bonds involving a given functional group, as well as their geometrical distribution as a function of water concentration. The comparison of our results with literature data has demonstrated that the fitting model is adequate to describe organic water mixtures. Finally, the role of water in the formation of the hydrophobic shell around the methyl group in diluted acetic acid water solutions has been discussed, evidencing how the methyl group hydrophobicity strongly influences the acetic acid behavior in aqueous solutions.

A novel high-performance liquid chromatography fingerprint approach to discriminate Phyllostachys pubescens from China

Background:A high-performance liquid chromatography fingerprint of different variants of Phyllostachys pubescens was developed for the source discrimination and quality control of Phyllostachys pubescens medicines produced in Zhejiang Province, China.Materials and Methods:Samples of Phyllostachys pubescens collected from nine cultivars in Zhejiang Province were used to establish the fingerprint. Taking the chromatographic peak (isoorientin) as the reference peak, the chromatographic column was Sunfire C18 ODS (250 mm×4.6 mm, 5 μm) at a column temperature of 25°C. The mobile phase was acetonitrile 0.8% acetic acid water solution (in a gradient elution mode) at a flow rate of 1 ml/min. The detection wavelength was 330 nm.Results:20 common peaks were established in the chromatographic fingerprints of Phyllostachys pubescens. And then by comparing the UV and standard substance with those of the authentic standards and literature, eight main peaks in the fingerprints were identified. Data of nine cultivars were evaluated statistically using similarity analysis, hierarchical cluster analysis (HCA) in order to establish a similarity standard of fingerprint for quality control of Phyllostachys pubescens, then to classify the samples. The similarity indexes were all above 0.95 between reference chromatogram and each sample's chromatogram.Conclusion:in this study, the methods established are reliable, and could be used to evaluate the quality and to identify the species of Phyllostachys pubescens in the future.