scholarly journals Effect of Solution Viscosity on the Precipitation of PSaMA in Aqueous Phase Separation-Based Membrane Formation

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1775
Author(s):  
Wouter Nielen ◽  
Joshua Willott ◽  
Julia Galicia ◽  
Wiebe de Vos
Keyword(s):  
Acetic Acid ◽  
Phase Separation ◽  
Aqueous Phase ◽  
Acid Concentration ◽  
Defect Formation ◽  
Solution Viscosity ◽  
Coagulation Bath ◽  
Additive Concentration ◽  
Nanofiltration Membranes ◽  
Casting Solution

Aqueous phase separation (APS) is a recently developed sustainable alternative to the conventional organic solvent based nonsolvent-induced phase separation (NIPS) method to prepare polymeric membranes. In APS, polyelectrolytes are precipitated from aqueous solutions through pH or salinity switches. Although APS differs from NIPS in the polymer and solvents, they share many tuning parameters. In this work, we investigate the APS-based preparation of membranes from poly(styrene-alt-maleic acid) (PSaMA) with a focus on acid concentration in the coagulation bath, and polymer and additive concentration in the casting solution. Nanofiltration membranes are prepared using significantly lower concentrations of acid: 0.3 M HCl compared to the 2 M of either acetic or phosphoric acid used in previous works. It is shown that higher polymer concentrations can be used to prevent defect formation in the top layer. In addition, acetic acid concentration also strongly affects casting solution viscosity and thus can be used to control membrane structure, where lower acetic acid concentrations can prevent the formation of macrovoids in the support structure. The prepared nanofiltration membranes exhibit a very low molecular weight cutoff (210 ± 40 dalton), making these sustainable membranes very relevant for the removal of contaminants of emerging concern. Understanding how the parameters described here affect membrane preparation and performance is essential to optimizing membranes prepared with APS towards this important application.

scholarly journals Effect of Temperature Exposition of Casting Solution on Properties of Polysulfone Hollow Fiber Membranes

Fibers ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 110 ◽  
Author(s):  
Ilya Borisov ◽  
Vladimir Vasilevsky ◽  
Dmitry Matveev ◽  
Anna Ovcharova ◽  
Alexey Volkov ◽  
...  
Keyword(s):  
Phase Separation ◽  
Thermal Treatment ◽  
Transport Properties ◽  
Hollow Fiber ◽  
Treatment Time ◽  
Solution Viscosity ◽  
Oxidative Destruction ◽  
Hollow Fiber Membranes ◽  
Selective Layer ◽  
Casting Solution

It was shown for the first time that the conditions of thermal treatment of the casting solution significantly affect the morphology and transport properties of porous, flat, and hollow fiber polysulfone (PSf) membranes. It is ascertained that the main solution components that are subjected to thermo-oxidative destruction are the pore-forming agent polyethylene glycol (PEG) and solvent N-methyl-2-pyrrolidone (NMP). It is proved that hydroxyl groups of PEG actively react in the process of the casting solution thermo-oxidative destruction. It is shown that despite the chemical conversion taking place in the casting solution, their stability towards coagulation virtually does not change. The differences in the membrane morphology associated with the increase of thermal treatment time at 120 °C are not connected to the thermodynamic properties of the casting solutions, but with the kinetics of the phase separation. It is revealed that the change of morphology and transport properties of membranes is connected with the increase of the casting solution viscosity. The rise of solution viscosity resulted in the slowdown of the phase separation and formation of a more densely packed membrane structure with less pronounced macropores. It is determined experimentally that with the increase of casting solution thermal treatment time, the membrane selective layer thickness increases. This leads to the decrease of gas permeance and the rise of the He/CO2 selectivity for flat and hollow fiber membranes. In the case of hollow fibers, the fall of gas permeance is also connected with the appearance of the sponge-like layer at the outer surface of membranes. The increase of selectivity and decline of permeance indicates the reduction of selective layer pore size and its densification, which agrees well with the calculation results of the average membrane density. The results obtained are relevant to any polymeric casting solution containing NMP and/or PEG and treated at temperatures above 60 °C.

scholarly journals The Combined Effects of Magnesium Oxide and Inulin on Intestinal Microbiota and Cecal Short-Chain Fatty Acids

Nutrients ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 152
Author(s):  
Kanako Omori ◽  
Hiroki Miyakawa ◽  
Aya Watanabe ◽  
Yuki Nakayama ◽  
Yijin Lyu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Acetic Acid ◽  
Dietary Fiber ◽  
Magnesium Oxide ◽  
Acid Concentration ◽  
Short Chain Fatty Acids ◽  
Water Soluble ◽  
Short Chain ◽  
Acetic Acid Concentration ◽  
Chain Fatty Acids

Constipation is a common condition that occurs in many people worldwide. While magnesium oxide (MgO) is often used as the first-line drug for chronic constipation in Japan, dietary fiber intake is also recommended. Dietary fiber is fermented by microbiota to produce short-chain fatty acids (SCFAs). SCFAs are involved in regulating systemic physiological functions and circadian rhythm. We examined the effect of combining MgO and the water-soluble dietary fiber, inulin, on cecal SCFA concentration and microbiota in mice. We also examined the MgO administration timing effect on cecal SCFAs. The cecal SCFA concentrations were measured by gas chromatography, and the microbiota was determined using next-generation sequencing. Inulin intake decreased cecal pH and increased cecal SCFA concentrations while combining MgO increased the cecal pH lowered by inulin and decreased the cecal SCFA concentrations elevated by inulin. When inulin and MgO were combined, significant changes in the microbiota composition were observed compared with inulin alone. The MgO effect on the cecal acetic acid concentration was less when administered at ZT12 than at ZT0. In conclusion, this study suggests that MgO affects cecal SCFA and microbiota during inulin feeding, and the effect on acetic acid concentration is time-dependent.

EUROPIUM OXALATE ION ASSOCIATION IN WATER

1966 ◽  
Vol 44 (24) ◽  
pp. 3057-3062 ◽  
Author(s):  
P. G. Manning
Keyword(s):  
Acetic Acid ◽  
Ionic Strength ◽  
Stability Constant ◽  
Stability Constants ◽  
Aqueous Phase ◽  
Sodium Acetate ◽  
Ion Association ◽  
Sodium Oxalate ◽  
Aqueous Sodium ◽  
Oxalate Ion

The partitioning of radiotracer 152/151Eu between aqueous sodium oxalate (Na2L) solutions and toluene solutions of thenoyltrifluoroacetone (HTTA) has been studied as a function of the oxalate concentration. The pH of the aqueous phase was controlled by means of sodium acetate – acetic acid mixtures and the ionic strength (I) by NaCl or NaClO4.At low ionic strengths (~0.05) and [L] ~10−4 M EuL+ formed, but at I = 0.95 and [L] ~10−3 M EuL2− also formed. Stability constants for the 1:1 and 1:2 (metal:ligand) complexes are reported.The magnitudes of the stepwise stability constant ratios are discussed.

scholarly journals Glycosyl-phosphatidylinositol-anchored membrane proteins can be distinguished from transmembrane polypeptide-anchored proteins by differential solubilization and temperature-induced phase separation in Triton X-114

1991 ◽  
Vol 280 (3) ◽  
pp. 745-751 ◽  
Author(s):  
N M Hooper ◽  
A Bashir
Keyword(s):  
Phase Separation ◽  
Membrane Proteins ◽  
Aqueous Phase ◽  
Hydrophobic Membrane ◽  
Rich Phase ◽  
Glycosyl Phosphatidylinositol ◽  
Ionic Detergent ◽  
Membrane Spanning ◽  
Triton X ◽  
Insoluble Pellet

Treatment of kidney microvillar membranes with the non-ionic detergent Triton X-114 at 0 degrees C, followed by low-speed centrifugation, generated a detergent-insoluble pellet and a detergent-soluble supernatant. The supernatant was further fractionated by phase separation at 30 degrees C into a detergent-rich phase and a detergent-depleted or aqueous phase. Those ectoenzymes with a covalently attached glycosyl-phosphatidylinositol (G-PI) membrane anchor were recovered predominantly (greater than 73%) in the detergent-insoluble pellet. In contrast, those ectoenzymes anchored by a single membrane-spanning polypeptide were recovered predominantly (greater than 62%) in the detergent-rich phase. Removal of the hydrophobic membrane-anchoring domain from either class of ectoenzyme resulted in the proteins being recovered predominantly (greater than 70%) in the aqueous phase. This technique was also applied to other membrane types, including pig and human erythrocyte ghosts, where, in both cases, the G-PI-anchored acetylcholinesterase partitioned predominantly (greater than 69%) into the detergent-insoluble pellet. When the microvillar membranes were subjected only to differential solubilization with Triton X-114 at 0 degrees C, the G-PI-anchored ectoenzymes were recovered predominantly (greater than 63%) in the detergent-insoluble pellet, whereas the transmembrane-polypeptide-anchored ectoenzymes were recovered predominantly (greater than 95%) in the detergent-solubilized supernatant. Thus differential solubilization and temperature-induced phase separation in Triton X-114 distinguished between G-PI-anchored membrane proteins, transmembrane-polypeptide-anchored proteins and soluble, hydrophilic proteins. This technique may be more useful and reliable than susceptibility to release by phospholipases as a means of identifying a G-PI anchor on an unpurified membrane protein.

Comparative Salmonella Spp. and Listeria monocytogenes Inactivation Rates in Four Commercial Mayonnaise Products

1991 ◽  
Vol 54 (12) ◽  
pp. 913-916 ◽  
Author(s):  
JOHN P. ERICKSON ◽  
PHYLLIS JENKINS
Keyword(s):  
Acetic Acid ◽  
Listeria Monocytogenes ◽  
Aqueous Phase ◽  
Population Declines ◽  
Salmonella Spp ◽  
Egg White Lysozyme ◽  
Consumer Safety ◽  
Safety Risks ◽  
Broad Cross Section ◽  
Formula Composition

Salmonella spp. and Listeria monocytogenes strains were inoculated into four commercial mayonnaise products: sandwich spread, real mayonnaise, reduced calorie mayonnaise dressing, and cholesterol-free reduced calorie mayonnaise dressing. Products represented a broad cross-section of aqueous phase acetic acid, salt, sucrose, and other compositional factors. Results showed that Salmonella spp. inactivation rates were unaffected by formula composition. The organism was rapidly inactivated, decreasing ≥8 log10 CFU/g in ≤72 h, in each of the four products. L. monocytogenes inactivation rates were directly correlated with aqueous phase acetic acid concentrations as follows: sandwich spread ≥ real mayonnaise > cholesterol-free reduced calorie mayonnaise dressing > reduced calorie mayonnaise dressing. L. monocytogenes inactivation rate in sandwich spread and real mayonnaise was similar to Salmonella spp. The reduced calorie mayonnaise dressings showed gradual, incremental population declines. L. monocytogenes decreased 3 and 5 log10 CFU/g in 72 h in reduced calorie and cholesterol-free reduced calorie mayonnaise dressings, respectively. The higher anti-listerial activity in the cholesterol free formulation was attributed to egg white lysozyme. This study documented that commercial mayonnaise, including reduced calorie mayonnaise dressing varieties, represent negligible consumer safety risks.

Optimization of pH and acetic acid concentration for bioconversion of hemicellulose from corncobs to xylitol by Candida tropicalis

2009 ◽  
Vol 43 (2) ◽  
pp. 203-207 ◽  
Author(s):  
Ke-Ke Cheng ◽  
Jian-An Zhang ◽  
Hong-Zhi Ling ◽  
Wen-Xiang Ping ◽  
Wei Huang ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Acid Concentration ◽  
Candida Tropicalis ◽  
Acetic Acid Concentration

Ru decorated carbon nanotubes – a promising catalyst for reforming bio-based acetic acid in the aqueous phase

2014 ◽  
Vol 16 (2) ◽  
pp. 864 ◽  
Author(s):  
D. J. M. de Vlieger ◽  
L. Lefferts ◽  
K. Seshan
Keyword(s):  
Carbon Nanotubes ◽  
Acetic Acid ◽  
Aqueous Phase

scholarly journals The hyaluronate synthase from a eukaryotic cell line

1993 ◽  
Vol 290 (3) ◽  
pp. 791-795 ◽  
Author(s):  
L Klewes ◽  
E A Turley ◽  
P Prehm
Keyword(s):  
Monoclonal Antibodies ◽  
Phase Separation ◽  
Affinity Chromatography ◽  
Cell Line ◽  
Aqueous Phase ◽  
Plasma Membranes ◽  
Eukaryotic Cell ◽  
Molecular Masses ◽  
Triton X ◽  
Hyaluronate Synthase

The hyaluronate synthase complex was identified in plasma membranes from B6 cells. It contained two subunits of molecular masses 52 kDa and 60 kDa which bound the precursor UDP-GlcA in digitonin solution and partitioned into the aqueous phase, together with nascent hyaluronate upon Triton X-114 phase separation. The 52 kDa protein cross-reacted with poly- and monoclonal antibodies raised against the streptococcal hyaluronate synthase and the 60 kDa protein was recognized by monoclonal antibodies raised against a hyaluronate receptor. The 52 kDa protein was purified to homogeneity by affinity chromatography with monoclonal anti-hyaluronate synthase.

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