scholarly journals Behavior of Volatile Compounds in Membrane Distillation: The Case of Carboxylic Acids

2020 ◽  
Author(s):  
Abdelaziz Khiter ◽  
Béatrice Balannec ◽  
Anthony Szymczyk ◽  
Omar Arous ◽  
Noureddine Nasrallah ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Volatile Compounds ◽  
Carboxylic Acids ◽  
Separation Efficiency ◽  
Fermentation Broth ◽  
Membrane Distillation ◽  
Acid Dissociation ◽  
Type Model ◽  
Operating Parameters ◽  
Suitable Alternative

<p> </p><p>Thanks to its unique features, membrane distillation (MD) has been particularly applied for desalination but also for niches applications with feed solutions containing a mixture of volatile molecules. For such solutions, the complex interplay of the solutes and solvent physicochemical and operating parameters makes it challenging to predict the separation efficiency by MD. There is thus a need for a better understanding of the behavior of volatile compounds in MD as well as the influence of their physicochemical environment. This study aimed at investigating the influence of different operating parameters on rejection efficiency of air-gap MD towards carboxylic acids (formic, acetic and succinic acids). Acid rejection was found to be highly dependent on the carboxylic acid structure. In addition, it increased with the acid concentration, which could be related to the formation of acid dimers in the feed solution. This behavior is opposite to what is classically observed for pressure-driven membrane processes thus suggesting that MD can be a suitable alternative to these techniques for the concentration/separation of carboxylic acids. On the other hand, acid rejection decreased with the increase of feed temperature which could be explained by the calculation of the apparent energies of activation of both the water and carboxylic acids using an Arrhenius-type model. Finally, the acid dissociation rate played a key role in the acid rejection. Taking advantage of this observation, it was demonstrated how a simple pH adjustment can be used to successfully achieve the selective separation of ethanol (compared to acetic acid) from an acetic acid/ethanol aqueous mixture (typical case of the extraction of bioethanol from a fermentation broth).</p> <p></p>

scholarly journals Behavior of Volatile Compounds in Membrane Distillation: The Case of Carboxylic Acids

2020 ◽  
Author(s):  
Abdelaziz Khiter ◽  
Béatrice Balannec ◽  
Anthony Szymczyk ◽  
Omar Arous ◽  
Noureddine Nasrallah ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Volatile Compounds ◽  
Carboxylic Acids ◽  
Separation Efficiency ◽  
Fermentation Broth ◽  
Membrane Distillation ◽  
Acid Dissociation ◽  
Type Model ◽  
Operating Parameters ◽  
Suitable Alternative

<p> </p><p>Thanks to its unique features, membrane distillation (MD) has been particularly applied for desalination but also for niches applications with feed solutions containing a mixture of volatile molecules. For such solutions, the complex interplay of the solutes and solvent physicochemical and operating parameters makes it challenging to predict the separation efficiency by MD. There is thus a need for a better understanding of the behavior of volatile compounds in MD as well as the influence of their physicochemical environment. This study aimed at investigating the influence of different operating parameters on rejection efficiency of air-gap MD towards carboxylic acids (formic, acetic and succinic acids). Acid rejection was found to be highly dependent on the carboxylic acid structure. In addition, it increased with the acid concentration, which could be related to the formation of acid dimers in the feed solution. This behavior is opposite to what is classically observed for pressure-driven membrane processes thus suggesting that MD can be a suitable alternative to these techniques for the concentration/separation of carboxylic acids. On the other hand, acid rejection decreased with the increase of feed temperature which could be explained by the calculation of the apparent energies of activation of both the water and carboxylic acids using an Arrhenius-type model. Finally, the acid dissociation rate played a key role in the acid rejection. Taking advantage of this observation, it was demonstrated how a simple pH adjustment can be used to successfully achieve the selective separation of ethanol (compared to acetic acid) from an acetic acid/ethanol aqueous mixture (typical case of the extraction of bioethanol from a fermentation broth).</p> <p></p>

scholarly journals Separation of volatile compounds from fermentation broth by membrane distillation

2011 ◽  
Vol 13 (3) ◽  
pp. 56-60 ◽  
Author(s):  
Marek Gryta ◽  
Marta Barancewicz
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Pore Size ◽  
Volatile Compounds ◽  
Fermentation Broth ◽  
Membrane Distillation ◽  
Volatile Components ◽  
Hydrophobic Properties ◽  
Fermentation Products ◽  
Polypropylene Membrane ◽  
Acetic Acids

Separation of volatile compounds from fermentation broth by membrane distillation The diluted ethanol solutions and fermentation broth (Saccharomyces cerevisiae) were separated by membrane distillation (MD). Hydrophobic macroporous (pore size 0.2 μm) capillary polypropylene membranes, Accurel PP V8/2 HF and Accurel PP S6/2, were used for these studies. The MD process can be successfully applied to remove the volatile components from the fermentation broth. Besides ethanol, propionic and acetic acids were moved from the broth to the distillate. Therefore, the course of the fermentation carried out in a membrane distillation bioreactor considerably accelerate its rate and increase the efficiency by a selective removal of fermentation products. It was found that the broth subjected to the separation did not affect the hydrophobic properties of the polypropylene membrane assembled in the MD modules.

scholarly journals Behavior of volatile compounds in membrane distillation: The case of carboxylic acids

2020 ◽  
Vol 612 ◽  
pp. 118453
Author(s):  
A. Khiter ◽  
B. Balannec ◽  
A. Szymczyk ◽  
O. Arous ◽  
N. Nasrallah ◽  
...  
Keyword(s):  
Volatile Compounds ◽  
Carboxylic Acids ◽  
Membrane Distillation

Microwave Irradiated Acetylation of p-Anisidine: A Step towards Green Chemistry

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Mousumi Chakraborty ◽  
Vaishali Umrigar ◽  
Parimal A. Parikh
Keyword(s):  
Acetic Acid ◽  
Reaction Time ◽  
Green Chemistry ◽  
Acetic Anhydride ◽  
Microwave Irradiation ◽  
Organic Solvent ◽  
Reaction Times ◽  
Microwave Energy ◽  
Operating Parameters ◽  
Feed Composition

The present study aims at assessing the effect of microwave irradiation against thermal heat on the production of N-acetyl-p-anisidine by acetylation of p-anisidine. The acetylation of p-anisidine under microwave irradiation produces N-acetyl-p-anisidine in shorter reaction times, which offers a benefit to the laboratories as well as industries. It also eliminates the use of excess solvent. Effects of operating parameters such as reaction time, feed composition, and microwave energy and reaction temperature on selectivity to the desired product have been investigated. The results indicate as high as a 98% conversion of N-acetyl-p-anisidine can be achieved within 12-15 minutes using acetic acid. The use of acetic acid as an acetylating agent against conventionally used acetic anhydride eliminates the handling of explosive acetic anhydride and also the energy intensive distillation step for separation of acetic acid. Organic solvent like acetic anhydride are not only hazardous to the environment, they are also expensive and flammable.

scholarly journals Demonstrating Pathogenicity of Enterobacter cloacae on Macadamia and Identifying Associated Volatiles of Gray Kernel of Macadamia in Hawaii

Plant Disease ◽  
2007 ◽  
Vol 91 (10) ◽  
pp. 1221-1228 ◽  
Author(s):  
K. A. Nishijima ◽  
M. M. Wall ◽  
M. S. Siderhurst
Keyword(s):  
Acetic Acid ◽  
Volatile Compounds ◽  
Enterobacter Cloacae ◽  
The Other ◽  
Biotic Factors ◽  
Macadamia Integrifolia ◽  
Abiotic And Biotic Factors ◽  
Foul Odor ◽  
Important Disease

Gray kernel is an important disease of macadamia (Macadamia integrifolia) that affects the quality of kernels, causing gray discoloration and a permeating, foul odor. Gray kernel symptoms were produced in raw, in-shell kernels of three cultivars of macadamia that were inoculated with strains of Enterobacter cloacae. Koch's postulates were fulfilled for three strains, demonstrating that E. cloacae is a causal agent of gray kernel. An inoculation protocol was developed to consistently reproduce gray kernel symptoms. Among the E. cloacae strains studied, macadamia strain LK 0802-3 and ginger strain B193-3 produced the highest incidences of disease (65 and 40%, respectively). The other macadamia strain, KN 04-2, produced gray kernel in 21.7% of inoculated nuts. Control treatments had 1.7% gray kernel symptoms. Some abiotic and biotic factors that affected incidence of gray kernel in inoculated kernels were identified. Volatiles of gray and nongray kernel samples also were analyzed. Ethanol and acetic acid were present in nongray and gray kernel samples, whereas volatiles from gray kernel samples included the additional compounds, 3-hydroxy-2-butanone (acetoin), 2,3-butanediol, phenol, and 2-methoxyphenol (guaiacol). This is believed to be the first report of the identification of volatile compounds associated with gray kernel.

scholarly journals Computational notes on the electronic properties of carboxylic acid

2020 ◽  
Vol 9 (2) ◽  
pp. 1079-1082
Keyword(s):  
Acetic Acid ◽  
Carboxylic Acid ◽  
Electronic Properties ◽  
Carboxylic Acids ◽  
Normal Mode ◽  
Normal Modes ◽  
Carboxyl Groups ◽  
Vibrational Characteristics ◽  
Vibrational Features ◽  
Acetic Acids

The present work describing the electronic properties and vibrational characteristics of carboxylic acids. Acetic acid is chosen as model molecules then optimized at B3LYP/6-31g(d,p) level of theory. The vibrational frequencies were calculated at the same level of theory. Band assignments which were calculated as 18 normal modes were assigned as one compare the normal mode coordinates with original one. Band assignments were described indicating the directions of normal modes in terms the vibrating atoms of the acetic acids. It could be concluded that DFT could be a useful tool for elucidation both the structural and vibrational features of carboxylic acids and then further utilized for assignment of the structures contains carboxyl groups which are known as most reactive structures in chemistry, biology and environment.

scholarly journals Heterogeneous chemistry of monocarboxylic acids on α-Al<sub>2</sub>O<sub>3</sub> at ambient condition

2010 ◽  
Vol 10 (2) ◽  
pp. 3937-3974 ◽  
Author(s):  
S. R. Tong ◽  
L. Y. Wu ◽  
M. F. Ge ◽  
W. G. Wang ◽  
Z. F. Pu
Keyword(s):  
Acetic Acid ◽  
Formic Acid ◽  
Carboxylic Acids ◽  
Propionic Acid ◽  
Ambient Condition ◽  
Heterogeneous Reactions ◽  
Dust Particles ◽  
Monocarboxylic Acids ◽  
Al2o3 Particles ◽  
Α Al2o3

Abstract. A study of the atmospheric heterogeneous reactions of formic acid, acetic acid, and propionic acid on dust particles (α-Al2O3) was performed at ambient condition by using a diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) reactor. From the analysis of the spectral features, observations of carboxylates formation provide strong evidence for an efficient reactive uptake process. Comparison of the calculated and experimental vibrational frequencies of adsorbed carboxylates establishes the bridging coordinated structures on the surface. The uptake coefficients of formic acid, acetic acid, and propionic acid on α-Al2O3 particles are (2.07±0.26)×10−3, (5.00±0.69)×10−3, and (3.04±0.63)×10−3, respectively (using geometric area). Besides, the effect of various relative humid (RH) on this heterogeneous reactions was studied. The uptake coefficients of monocarboxylic acids on α-Al2O3 particles increase initially (RH<20%) and then decrease with the increased RH (RH>20%) which was due to the effect of water on carboxylic acids solvation, particles surface hydroxylation, and competition on reactive site. On the basis of the results of experimental simulation, the mechanism of heterogeneous reaction of dust with carboxylic acids at ambient condition was discussed. The loss of atmospheric monocarboxylic acids due to reactive uptake on available mineral dust particles can be competitive with homogeneous loss pathways, especially in dusty urban and desertified environments.

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