scholarly journals Effects of reaction conditions on the degree of substitution in acetylated nanocellulose

2020 ◽  
Vol 9 (4) ◽  
Author(s):  
Thien Doan Van Hong ◽  
Nhu Tran Thao ◽  
Trang Do Thi Kieu ◽  
Chanh-Nghiem Nguyen ◽  
Toan Pham Van ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Reaction Temperature ◽  
1H Nmr Spectroscopy ◽  
Interaction Effects ◽  
Degree Of Substitution ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Acid Ratio ◽  
Temperature Time ◽  
Three Factor

In this study, cellulose nanocrystals (CNC) were chemically extracted from the waste newspapers and acetylated by reacting CNC with acetic anhydride, using sulfuric acid as a catalyst. Response Surface Methodology based on a three-factor factorial design was applied to analyze the interaction effects of reaction temperature, time, and the ratio of nanocellulose and acetic acid (wt/v) on the degree of substitution (DS) which was calculated and compared. Various experimental conditions as reaction temperature (50-70 °C), reaction time (90-150 min), and the ratio of nanocellulose and acetic acid (wt/v) (1:15-1:25) were under investigation. It was found that reaction temperature and its interaction effects have the most significant effects on DS. The acetylated CNC was characterized by FTIR and 1H-NMR spectroscopy. The highest DS (2.997) was obtained in 90 min and the CNC/acetic acid ratio of 1:15 at 70 °C.

scholarly journals Effects of reaction conditions on the degree of substitution in acetylated nanocellulose

2020 ◽  
Vol 9 (4) ◽  
Author(s):  
Thien Doan Van Hong ◽  
Nhu Tran Thao ◽  
Trang Do Thi Kieu ◽  
Chanh-Nghiem Nguyen ◽  
Toan Pham Van ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Reaction Temperature ◽  
1H Nmr Spectroscopy ◽  
Interaction Effects ◽  
Degree Of Substitution ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Acid Ratio ◽  
Temperature Time ◽  
Three Factor

In this study, cellulose nanocrystals (CNC) were chemically extracted from the waste newspapers and acetylated by reacting CNC with acetic anhydride, using sulfuric acid as a catalyst. Response Surface Methodology based on a three-factor factorial design was applied to analyze the interaction effects of reaction temperature, time, and the ratio of nanocellulose and acetic acid (wt/v) on the degree of substitution (DS) which was calculated and compared. Various experimental conditions as reaction temperature (50-70 °C), reaction time (90-150 min), and the ratio of nanocellulose and acetic acid (wt/v) (1:15-1:25) were under investigation. It was found that reaction temperature and its interaction effects have the most significant effects on DS. The acetylated CNC was characterized by FTIR and 1H-NMR spectroscopy. The highest DS (2.997) was obtained in 90 min and the CNC/acetic acid ratio of 1:15 at 70 °C.

Synthesis of Several Sugar Acetates and their Structures Characterization

2012 ◽  
Vol 602-604 ◽  
pp. 1373-1378
Author(s):  
Jing Liang ◽  
Zhen Xing Cheng ◽  
Lian Yuan Wang ◽  
Hai Yan Zhu ◽  
Shi Gao ◽  
...  
Keyword(s):  
Reaction Time ◽  
Acetic Anhydride ◽  
Reaction Temperature ◽  
Soluble Starch ◽  
Degree Of Substitution ◽  
High Yield ◽  
Reaction Conditions ◽  
Alkaline Catalyst ◽  
Acetate Esters ◽  
Acidic Catalyst

Several acetate esters were synthesized by reacting sugars, i.e. glucose, soluble starch, and dextrin, with acetic anhydride in the presence of some catalysts. Their structures were confirmed by IR and MS. Influences of the reaction conditions, such as catalyst and its dosage, reaction time, reaction temperature and acetic anhydride content, on the value of degree of substitution (DS) and the yield for starch acetates had also been investigated. Results showed that glucose could be easily completely acetylated; acidic catalyst tended to form a configuration of α-glucose penta-acetate (α-GPA), while alkaline catalyst β-GPA. However, soluble starch and dextrin were more difficult to be completely substituted by acetic anhydride. The DS value of soluble starch was below 2; for dextrin, its DS value could reach 2.3, close to the theoretical value of 3. An appropriate reaction temperature and reaction time were important for high yield as well as high DS value.

scholarly journals Validation Of Spectrophotometry-Visble Method On The Determination Of Borax Levels In Meatballs

2021 ◽  
Vol 8 (2) ◽  
pp. 41
Author(s):  
Sudjarwo Sudjarwo ◽  
Poedjiarti S ◽  
Angerina N
Keyword(s):  
Acetic Acid ◽  
Sulphuric Acid ◽  
Glacial Acetic Acid ◽  
Food Product ◽  
Reaction Conditions ◽  
Optimum Result ◽  
Quantitation Limit ◽  
Temperature Time

Borax, in illictic additive substance, is added on certain food product as a e preservative and rubbery. Therefore, the determination of borax in the food product such as meatball is very impotant in view of meatball is a food product often consumed by community. Vis- Spectrophotometric method with curcumine 0.125% as a reagent and glacial acetic acid-sulphuric acid has been used for determination of borax in this research. Curcumin reagent was selected because sensitivity of the method and the reproducibility of the results are affected by quality of the reagent other than rigorous observance of the reaction conditions (temperature, time, reagent quantities). Glacial acetic acid- sulphuric acid was used to create acid condition, so that curcumin and boron form a violetred 2:1 complex called rosocyanin. The optimum result was obtained when 1/. ml solution of 0.125% curcuumin and 1.0 ml concentrated sulphuric acid were added and the absorbance was measured after 70 minutes at 547 nm. The results showed linear regression y = 1.3127x – 0.0994, r = 0.9690 > r table (n = 5) is 0.878 and p = 0.007 (p< 0.01) and Vxo is was 15,53%. The detection limit and quantitation limit were 9.7.10-4 ppm and 2.94. 10-3 ppm respectively. The recovery and coefficient variation were 47.56%±3,92%. Determination of borax in three meatball samples which were taken from a location in Surabaya showed that the sample contained borax with concentration of 0.0205; 0.0151; 0.0210 (% w/w) respectively.

Catalytic Oxidation of o-chlorotoluene to o-chlorobenzaldehyde by Vanadium Doped Anatase Mesoporous TiO2

2013 ◽  
Vol 781-784 ◽  
pp. 182-185 ◽  
Author(s):  
Sheng Chun Yang ◽  
Jia Qiang Wang
Keyword(s):  
Acetic Acid ◽  
Reaction Time ◽  
Catalytic Oxidation ◽  
Reaction Temperature ◽  
Catalytic Reaction ◽  
Conversion Rate ◽  
Reaction Conditions ◽  
Novel Method

A novel method for the catalytic oxidation of o-chlorotoluene (OCT) to o-chlorobenzaldehyde (CBD) was proposed using vanadium doped anatase mesoporous TiO2 (V/MTiO2), the catalytic reaction conditions were investigated. Under the optimum catalytic reaction conditions: 10 mL of acetic acid 100 °C of reaction temperature, 10 h of reaction time and 100 mg of catalyst, the conversion rate of OCT could reach to 95.3%, with a selectivity of 63.5%.

Effect of water on wood liquefaction and the properties of phenolated wood

Holzforschung ◽  
2005 ◽  
Vol 59 (6) ◽  
pp. 628-634 ◽  
Author(s):  
Seung-Hwan Lee ◽  
Siqun Wang
Keyword(s):  
Activation Energy ◽  
Reaction Temperature ◽  
Weight Ratio ◽  
Flexural Properties ◽  
Phenol Content ◽  
Reaction Conditions ◽  
Wood Residue ◽  
Wood Liquefaction ◽  
Temperature Time ◽  
Phenolated Wood

Abstract The effects of water on wood liquefaction were investigated under various reaction conditions: reaction temperature, time, and wood/phenol weight ratio. Although the addition of water decreased the reaction temperature and reduced the liquefaction rate and combined phenol content of the resulting phenolated wood, residue of <20% and a combined phenol content of >95% were obtained by controlling the reaction conditions. The addition of water suppressed an increase in the combined phenol content and molecular weight by a recondensation reaction observed in liquefaction in the absence of water under the same reaction conditions. Phenolated wood obtained in the presence of water showed comparable thermoflow properties and slightly higher activation energy for cure when compared with phenolated wood obtained in the absence of water. Moldings from both phenolated woods showed comparable flexural properties to those of moldings from commercial Novolak resin.

scholarly journals Catalytic Synthesis of Acetonitrile by Ammonolysis of Acetic Acid

2017 ◽  
Vol 3 (3) ◽  
pp. 173 ◽  
Author(s):  
S.I. Galanov ◽  
O.I. Sidorova ◽  
A.K. Golovko ◽  
V.D. Philimonov ◽  
L.N. Kurina ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Reaction Temperature ◽  
Elevated Temperatures ◽  
Catalyst Layer ◽  
Product Formation ◽  
Catalytic Synthesis ◽  
Reagent Ratio ◽  
Acid Ratio ◽  
Effect Of The Composition ◽  
Catalyst Lifetime

The influence of principal parameters (reagent ratio, reaction temperature, temperature gradients along a catalyst layer) on the yield of the desired product was studied in the reaction of acetonitrile synthesis from acetic acid over γ-alumina. Thus, the increase in ammonia:acetic acid ratio leads to the increase in acetonitrile selectivity and yield. In this work it has been demonstrated that initial temperatures of 360-380 °C are optimum to effectively carry out the process of acetonitrile synthesis. The increase in reaction temperature allows one to increase the yield of acetonitrile, but at elevated temperatures the catalyst carbidization and contamination of the desired product were observed. The additives to the reaction mixture of the substances that decrease the rate of compaction products (CP) formation and participate in the desired product formation are very effective for decreasing the catalyst carbidization. The effect of the composition of a reaction mixture on a catalyst lifetime is considered. The addition of ethyl acetate to acetic acid promotes a greater carbidization as compared to pure acetic acid. The application of a mixture of acetic acid with acetic anhydride at similar acetonitrile yield decreases the catalyst carbidization.

Study on the Hydrolysis of PET Catalyzed by Carbonates under Microwave Irradiation

2014 ◽  
Vol 1078 ◽  
pp. 36-39
Author(s):  
Zhi De Liu ◽  
Xin Zhang ◽  
Mi Mi Wang ◽  
Dong Zhang
Keyword(s):  
Reaction Time ◽  
Reaction Temperature ◽  
Influence Factors ◽  
Experimental Conditions ◽  
Zinc Carbonate ◽  
Hydrolytic Reaction ◽  
Microwave Hydrolysis ◽  
Catalyst Dosage ◽  
Hydrolysis Of ◽  
Temperature Time

A study for optimizing the experimental conditions for the hydrolysis of polyethylene terephthalate (PET) catalyzed by carbonates was performed. The main influence factors of PET microwave hydrolytic reaction, such as the reaction temperature, time and catalyst dosage, were confirmed and these effects on the catalysis of PET microwave hydrolysis were studied in detail. The results showed that the sequence of influence factors was reaction temperature>reaction time> catalyst dosage. The optimal experimental conditions under the catalyst of basic zinc carbonate were that the catalyst dosage, 0.75%; the reaction time, 210 min; the reaction temperature, 200°C.

Oxidation of Ethanol on Sn-Mo Oxide Catalysts

1992 ◽  
Vol 57 (3) ◽  
pp. 439-445
Author(s):  
Magdy A. Wassel ◽  
Nalla K. Allahaverdova ◽  
Tofki G. Alkhazov
Keyword(s):  
Acetic Acid ◽  
Potassium Hydroxide ◽  
Pulse Method ◽  
Conversion Ratio ◽  
Mo Catalyst ◽  
Acid Ratio ◽  
Aqueous Potassium Hydroxide ◽  
The Stability ◽  
Primary Oxidation ◽  
Oxidation Of Ethanol

To determine the acidic and basic properties of the title catalysts, the adsorption of NH3 and SO2 was compared using pulse method. It was found that this characteristics undergoes changes when the Sn-Mo catalyst is treated with aqueous potassium hydroxide solutions of different concentrations. The catalyst treated with the more concentrated KOH solution possesses mainly properties of a base. When studying the oxidation of ethanol it has been found that the αCO2/αaldehyde conversion ratio increases with the time of contact of the mixture with the catalyst while the αCO2/α acid ratio is not affected. The study of two alcohols deuterated either in OH group (C2H5OD) or in the alkyl group ((C2D5OH) has shown that the substitution of C-H for C-D bond enhances the stability of the primary oxidation product, deuterated ethanal, so that it is not transformed further to acetic acid.

scholarly journals Software-guided microscale flow calorimeter for efficient acquisition of thermokinetic data

2021 ◽  
Author(s):  
Timothy Aljoscha Frede ◽  
Marlene Dietz ◽  
Norbert Kockmann
Keyword(s):  
Design Of Experiments ◽  
Process Development ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Flow Calorimeter ◽  
Microscale Flow ◽  
Increased Sensitivity ◽  
Important Time ◽  
Optimal Reaction

AbstractFast chemical process development is inevitably linked to an optimized determination of thermokinetic data of chemical reactions. A miniaturized flow calorimeter enables increased sensitivity when examining small amounts of reactants in a short time compared to traditional batch equipment. Therefore, a methodology to determine optimal reaction conditions for calorimetric measurement experiments was developed and is presented in this contribution. Within the methodology, short-cut calculations are supplemented by computational fluid dynamics (CFD) simulations for a better representation of the hydrodynamics within the microreactor. This approach leads to the effective design of experiments. Unfavourable experimental conditions for kinetics experiments are determined in advance and therefore, need not to be considered during design of experiments. The methodology is tested for an instantaneous acid-base reaction. Good agreement of simulations was obtained with experimental data. Thus, the prediction of the hydrodynamics is enabled and the first steps towards a digital twin of the calorimeter are performed. The flow rates proposed by the methodology are tested for the determination of reaction enthalpy and showed that reasonable experimental settings resulted. Graphical abstract A methodology is suggested to evaluate optimal reaction conditions for efficientacquisition of kinetic data. The experimental design space is limited by thestepwise determination of important time scales based on specified input data.

scholarly journals Analytical Rheology of Honey: A State-of-the-Art Review

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1709
Author(s):  
Célia Faustino ◽  
Lídia Pinheiro
Keyword(s):  
Sugar Content ◽  
Rheological Behaviour ◽  
Principal Component ◽  
Rheological Parameters ◽  
Experimental Conditions ◽  
Thixotropic Behaviour ◽  
Ancient Times ◽  
Medicinal Properties ◽  
Complex Relationships ◽  
Temperature Time

Honey has been used as a nutraceutical product since ancient times due to its nutritional and medicinal properties. Honey rheology influences its organoleptic properties and is relevant for processing and quality control. This review summarizes the rheological behaviour of honeys of different botanical source(s) and geographical locations that has been described in the literature, focusing on the relation between rheological parameters, honey composition (moisture, water activity, sugar content, presence of colloidal matter) and experimental conditions (temperature, time, stress, shear rate). Both liquid and crystallized honeys have been addressed. Firstly, the main mathematical models used to describe honey rheological behaviour are presented highlighting moisture and temperature effects. Then, rheological data from the literature regarding distinct honey types from different countries is analysed and results are compared. Although most honeys are Newtonian fluids, interesting shear-thinning and thixotropic as well as anti-thixotropic behaviour have been described for some types of honey. Rheological parameters have also been successfully applied to identify honey adulteration and to discriminate between different honey types. Several chemometric techniques have also been employed to obtain the complex relationships between honey physicochemical and rheological properties, including partial least squares (PLS), principal component analysis (PCA) and artificial neural networks (ANN).

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