scholarly journals Effect of pH on the performance of an acidic biotrickling filter for simultaneous removal of H2S and siloxane from biogas

2021 ◽  
Vol 83 (7) ◽  
pp. 1511-1521
Author(s):  
Yuyao Zhang ◽  
Kazuyuki Oshita ◽  
Masaki Takaoka ◽  
Yu Kawasaki ◽  
Daisuke Minami ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Partition Coefficient ◽  
Sodium Hydroxide Solution ◽  
Sulfur Oxidation ◽  
Linear Increase ◽  
Simultaneous Removal ◽  
Acidic Ph ◽  
Oxidation Activity ◽  
Ph Conditions ◽  
Low Sulfur

Abstract Acidic biotrickling filters (BTF) can be used for simultaneous removal of hydrogen sulfide (H2S) and siloxane from biogas. In this study, the performance of a BTF under different acidic pH conditions was investigated. The removal profile of H2S showed that 90% of H2S removal was achieved during the first 0.4 m of BTF height with down-flow biogas. Decamethylcyclopentasiloxane (D5) removal decreased from 34.5% to 15.6% when the pH increased from 0.88 to 3.98. Furthermore, the high partition coefficient of D5 obtained in under higher pH condition was attributed to the higher total ionic strength resulting from the addition of sodium hydroxide solution and mineral medium. The linear increase in D5 removal with the mass transfer coefficient (kL) indicated that the acidic recycling liquid accelerated the mass transfer of D5 in the BTF. Therefore, the lower partition coefficient and higher kL under acidic pH conditions lead to the efficient removal of D5. However, the highly acidic pH 0.9 blocked mass transfer of H2S and O2 gases to the recycling liquid. Low sulfur oxidation activity and low Acidithiobacillus sp. content also deteriorated the biodegradation of H2S. Operating the BTF at pH 1.2 was optimal for simultaneously removing H2S and siloxane.

scholarly journals Heterocyclic boronic acids display sialic acid selective binding in a hypoxic tumor relevant acidic environment

2017 ◽  
Vol 8 (9) ◽  
pp. 6165-6170 ◽  
Author(s):  
A. Matsumoto ◽  
A. J. Stephenson-Brown ◽  
T. Khan ◽  
T. Miyazawa ◽  
H. Cabral ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Boronic Acids ◽  
Sialic Acids ◽  
Strong Interactions ◽  
Acidic Ph ◽  
Acidic Environment ◽  
Selective Binding ◽  
High Affinity ◽  
Ph Conditions ◽  
Hypoxic Tumor

A group of heterocyclic boronic acids demonstrating unusually high affinity and selectivity for sialic acids are described, with strong interactions under the weakly acidic pH conditions associated with a hypoxic tumoral microenvironment.

The heat/mass transfer to a finite strip at small Péclet numbers

1978 ◽  
Vol 86 (1) ◽  
pp. 49-65 ◽  
Author(s):  
R. C. Ackerberg ◽  
R. D. Patel ◽  
S. K. Gupta
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Shear Flow ◽  
Sodium Hydroxide Solution ◽  
Flow Direction ◽  
Mathematical Problem ◽  
Limiting Current ◽  
Transfer Rates ◽  
Uniform Shear ◽  
Uniform Shear Flow

The problem of heat transfer (or mass transfer at low transfer rates) to a strip of finite length in a uniform shear flow is considered. For small values of the Péclet number (based on wall shear rate and strip length), diffusion in the flow direction cannot be neglected as in the classical Leveque solution. The mathematical problem is solved by the method of matched asymptotic expansions and expressions for the local and overall dimensionless heat-transfer rate from the strip are found. Experimental data on wall mass-transfer rates in a tube at small Péclet numbers have been obtained by the well-known limiting-current method using potassium ferrocyanide and potassium ferricyanide in sodium hydroxide solution. The Schmidt number is large, so that a uniform shear flow can be assumed near the wall. Experimental results are compared with our theoretical predictions and the work of others, and the agreement is found to be excellent.

scholarly journals Freeze-Drying of Blueberries: Effects of Carbon Dioxide (CO2) Laser Perforation as Skin Pretreatment to Improve Mass Transfer, Primary Drying Time, and Quality

Foods ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 211 ◽  
Author(s):  
Pablo Munzenmayer ◽  
Jaime Ulloa ◽  
Marlene Pinto ◽  
Cristian Ramirez ◽  
Pedro Valencia ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Co2 Laser ◽  
Freeze Drying ◽  
Sharp Decrease ◽  
Linear Increase ◽  
Vapor Flow ◽  
Drying Time ◽  
Transfer Resistance ◽  
Freeze Dried ◽  
Phenomenological Perspective

Freeze-dried berry fruits are generally consumed as they are, whole and without peeling or cutting, as the conservation of their original shape and appearance is often desired for the final product. However, usually, berries are naturally wrapped by an outer skin that imparts a barrier to vapor flow during freeze-drying, causing berry busting. Photo-sequence, experimental, and theoretical methodologies were applied to evaluate the application of CO2 laser microperforations to blueberry skin. Under the same set of freeze-drying conditions, blueberries with and without perforations were processed. The results showed that the primary drying time was significantly reduced from 17 ± 0.9 h for nontreated berries to 13 ± 2.0 h when nine microperforations per berry fruit were made. Concomitantly, the quality was also significantly improved, as the percentage of nonbusted blueberries at the end of the process increased from an average of 47% to 86%. From a phenomenological perspective, the analysis of the mass transfer resistance of nontreated fruits, in agreement with reported studies, showed a Type II curvature, with a sharp decrease at low time, followed by a linear increase. In contrast, blueberries with nine perforations depicted a Type III regime, with a saturation curvature toward the time axis. It was demonstrated that CO2-laser microperforation has high potential as a skin pretreatment for the freeze-drying of blueberries.

Modeling of acetate-type fermentation of sugar-containing wastewater under acidic pH conditions

2018 ◽  
Vol 248 ◽  
pp. 148-155 ◽  
Author(s):  
Liang Huang ◽  
Xin-Rong Pan ◽  
Ya-Zhou Wang ◽  
Chen-Xuan Li ◽  
Chang-Bin Chen ◽  
...  
Keyword(s):  
Acidic Ph ◽  
Ph Conditions

scholarly journals An Acid-activated Nucleobase Transporter from Leishmania major

2009 ◽  
Vol 284 (24) ◽  
pp. 16164-16169 ◽  
Author(s):  
Diana Ortiz ◽  
Marco A. Sanchez ◽  
Hans P. Koch ◽  
H. Peter Larsson ◽  
Scott M. Landfear
Keyword(s):  
Leishmania Major ◽  
De Novo ◽  
Low Ph ◽  
Acidic Ph ◽  
Physiological Conditions ◽  
Neutral Ph ◽  
Amastigote Stage ◽  
Electrode Voltage ◽  
Ph Conditions ◽  
Micromolar Range

Parasitic protozoa are unable to synthesize purines de novo and must import preformed purine nucleobases or nucleosides from their hosts. Leishmania major expresses two purine nucleobase transporters, LmaNT3 and LmaNT4. Previous studies revealed that at neutral pH, LmaNT3 is a broad specificity, high affinity nucleobase transporter, whereas LmaNT4 mediates the uptake of only adenine. Because LmaNT4 is required for optimal viability of the amastigote stage of the parasite that lives within acidified phagolysomal vesicles of mammalian macrophages, the function of this permease was examined under acidic pH conditions. At acidic pH, LmaNT4 acquires the ability to transport adenine, hypoxanthine, guanine, and xanthine with Km values in the micromolar range, indicating that this transporter is activated at low pH. Thus, LmaNT4 is an acid-activated purine nucleobase transporter that functions optimally under the physiological conditions the parasite is exposed to in the macrophage phagolysosome. In contrast, LmaNT3 functions optimally at neutral pH. Two-electrode voltage clamp experiments performed on LmaNT3 and LmaNT4 expressed in Xenopus oocytes revealed substrate-induced inward directed currents at acidic pH, and application of substrates induced acidification of the oocyte cytosol. These observations imply that LmaNT3 and LmaNT4 are nucleobase/proton symporters.

Electrochemical reduction of hydrogen peroxide on SIMFUEL (UO2) in acidic pH conditions

2012 ◽  
Vol 83 ◽  
pp. 410-419 ◽  
Author(s):  
Mayuri Razdan ◽  
David S. Hall ◽  
Peter G. Keech ◽  
David W. Shoesmith
Keyword(s):  
Hydrogen Peroxide ◽  
Electrochemical Reduction ◽  
Acidic Ph ◽  
Ph Conditions

N-acetyl-L-aspartate and acetate1H NMR signal overlapping under mild acidic pH conditions

1993 ◽  
Vol 29 (5) ◽  
pp. 692-694 ◽  
Author(s):  
Magali Marti ◽  
Julie Labouesse ◽  
Paul Canioni ◽  
Michel Merle
Keyword(s):  
Acidic Ph ◽  
Ph Conditions
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