Testing the stability of magnetic iron oxides/kaolinite nanocomposite under various pH conditions

2017 ◽  
Vol 253 ◽  
pp. 329-335 ◽  
Author(s):  
Michaela Tokarčíková ◽  
Jonáš Tokarský ◽  
Kateřina Mamulová Kutláková ◽  
Jana Seidlerová
Keyword(s):  
Iron Oxides ◽  
Ph Conditions ◽  
The Stability

scholarly journals Adsorption of p-Arsanilic Acid on Iron (Hydr)oxides and Its Implications for Contamination in Soils

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 105
Author(s):  
Yifan Yang ◽  
Shiyong Tao ◽  
Zhichun Dong ◽  
Jing Xu ◽  
Xiang Zhang ◽  
...  
Keyword(s):  
Iron Oxides ◽  
Organic Matter Content ◽  
Feed Additives ◽  
Unit Surface Area ◽  
Potential Hazard ◽  
Order Kinetic ◽  
Positive Correlation ◽  
Arsanilic Acid ◽  
Organic Arsenic ◽  
Ph Conditions

Because of the diversification of industries in developing cities, the phenomenon of the simultaneous contamination of various kinds of pollutants is becoming common, and the environmental process of pollutants in multi-contaminated environmental mediums has attracted attention in recent years. In this study, p-arsanilic acid (ASA), a kind of organic arsenic feed additive that contains the arsenic group in a chemical structure, is used as a typical contaminant to investigate its adsorption on iron oxides and its implication for contaminated soils. The adsorption kinetics on all solids can be fitted to the pseudo-second-order kinetic model well. At the same mass dosage conditions, the adsorption amount per unit surface area on iron oxides follows the order α-FeOOH > γ-Fe2O3 > α-Fe2O3, which is significantly higher than that for actual soil, because of the lower content of iron oxides in actual soil. Lower pH conditions favor ASA adsorption, while higher pH conditions inhibit its adsorption as a result of the electrostatic repulsion and weakened hydrophobic interaction. The presence of phosphate also inhibits ASA adsorption because of the competitive effect. Correlations between the amount of ASA adsorption in actual soil and the Fe2O3 content, total phosphorus content, arsenic content, and organic matter content of actual soil are also investigated in this work, and a moderate positive correlation (R2 = 0.630), strong negative correlation (R2 = 0.734), insignificant positive correlation (R2 = 0.099), and no correlation (R2 = 0.006) are found, respectively. These findings would help evaluate the potential hazard of the usage of organic arsenic feed additives, as well as further the understanding of the geochemical processes of contaminants in complicated mediums.

scholarly journals Stability of Methylphenidate under Various pH Conditions in the Presence or Absence of Gut Microbiota

2021 ◽  
Vol 14 (8) ◽  
pp. 733
Author(s):  
Julia Aresti-Sanz ◽  
Markus Schwalbe ◽  
Rob Rodrigues Pereira ◽  
Hjalmar Permentier ◽  
Sahar El Aidy
Keyword(s):  
Gut Microbiota ◽  
In Silico Analysis ◽  
Intestinal Bacteria ◽  
Inactive Form ◽  
High Interindividual Variability ◽  
Ritalinic Acid ◽  
Ph Conditions ◽  
Small Intestinal ◽  
The Stability ◽  
Hydrolysis Of

Methylphenidate is one of the most widely used oral treatments for attention-deficit/hyperactivity disorder (ADHD). The drug is mainly absorbed in the small intestine and has low bioavailability. Accordingly, a high interindividual variability in terms of response to the treatment is known among ADHD patients treated with methylphenidate. Nonetheless, very little is known about the factors that influence the drug’s absorption and bioavailability. Gut microbiota has been shown to reduce the bioavailability of a wide variety of orally administered drugs. Here, we tested the ability of small intestinal bacteria to metabolize methylphenidate. In silico analysis identified several small intestinal bacteria to harbor homologues of the human carboxylesterase 1 enzyme responsible for the hydrolysis of methylphenidate in the liver into the inactive form, ritalinic acid. Despite our initial results hinting towards possible bacterial hydrolysis of the drug, up to 60% of methylphenidate is spontaneously hydrolyzed in the absence of bacteria and this hydrolysis is pH-dependent. Overall, our results indicate that the stability of methylphenidate is compromised under certain pH conditions in the presence or absence of gut microbiota.

scholarly journals Change in the stability of goat milk and cow milk due to pH and heat

2021 ◽  
Vol 233 ◽  
pp. 02046
Author(s):  
Xiaoxue Fan ◽  
Ming Cheng ◽  
Xiaoning Zhang ◽  
Cunfang Wang ◽  
Hua Jiang
Keyword(s):  
Thermal Stability ◽  
Milk Production ◽  
Ph Value ◽  
Goat Milk ◽  
Cow Milk ◽  
Type B ◽  
Fresh Milk ◽  
Ph Conditions ◽  
The Stability ◽  
Thermal Stability Of

This paper aimed to evaluate the changes in the thermal stability of goat milk, cow milk and homogenized milk under different pH conditions. The results showed that goat milk was of type B milk, and the thermal stability were positively correlated with the pH value. But cow milk was of type A milk, the most stable pH of fresh milk was 6.9, while it was 6.7 for homogenized cow milk. Compared with cow milk, the acidification of goat milk was stronger due to heat. Therefore, in the process of milk production, the germicidal heating conditions of two different milk sources should be determined according to their thermal stability.

scholarly journals In Vitro and In Vivo Assessment of the Potential of Escherichia coli Phages to Treat Infections and Survive Gastric Conditions

2021 ◽  
Vol 9 (9) ◽  
pp. 1869
Author(s):  
Joanna Kaczorowska ◽  
Eoghan Casey ◽  
Gabriele A. Lugli ◽  
Marco Ventura ◽  
David J. Clarke ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Galleria Mellonella ◽  
Enterotoxigenic Escherichia Coli ◽  
E Coli ◽  
Composite Mixture ◽  
Ph Conditions ◽  
The Stability ◽  
Higher Sensitivity

Enterotoxigenic Escherichia coli (ETEC) and Shigella ssp. infections are associated with high rates of mortality, especially in infants in developing countries. Due to increasing levels of global antibiotic resistance exhibited by many pathogenic organisms, alternative strategies to combat such infections are urgently required. In this study, we evaluated the stability of five coliphages (four Myoviridae and one Siphoviridae phage) over a range of pH conditions and in simulated gastric conditions. The Myoviridae phages were stable across the range of pH 2 to 7, while the Siphoviridae phage, JK16, exhibited higher sensitivity to low pH. A composite mixture of these five phages was tested in vivo in a Galleria mellonella model. The obtained data clearly shows potential in treating E. coli infections prophylactically.

Effects of gastrointestinal pH conditions on the stability of the β-lactoglobulin/vitamin D3 complex and on the solubility of vitamin D3

2013 ◽  
Vol 52 (2) ◽  
pp. 515-521 ◽  
Author(s):  
Fatoumata Diarrassouba ◽  
Gabriel Remondetto ◽  
Li Liang ◽  
Ghislain Garrait ◽  
Eric Beyssac ◽  
...  
Keyword(s):  
Vitamin D3 ◽  
Gastrointestinal Ph ◽  
Ph Conditions ◽  
The Stability ◽  
Β Lactoglobulin

scholarly journals Stability Study of Isoniazid and Rifampicin Oral Solutions Using Hydroxypropyl-Β-Cyclodextrin to Treat Tuberculosis in Paediatrics

Pharmaceutics ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 195
Author(s):  
Ana Santoveña-Estévez ◽  
Javier Suárez-González ◽  
Amor R. Cáceres-Pérez ◽  
Zuleima Ruiz-Noda ◽  
Sara Machado-Rodríguez ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Stability Study ◽  
Active Pharmaceutical Ingredients ◽  
Adherence To Treatment ◽  
Pharmaceutical Ingredients ◽  
Antituberculosis Treatment ◽  
Maximum Stability ◽  
Ph Conditions ◽  
The Stability

(1) Background: First-line antituberculosis treatment in paediatrics entails the administration of Isoniazid, Pyrazinamide, and Rifampicin. This study examines the possibility of developing a combined dose liquid formulation for oral use that would facilitate dose adjustment and adherence to treatment for younger children. (2) Methods: The active pharmaceutical ingredients stability under in vitro paediatric digestive pH conditions have been checked. The samples were studied as individual or fixed combined paediatric dosages to determine the pH of maximum stability. The use of hydroxypropyl-β-cyclodextrin to improve Rifampicin solubility and the use of ascorbic acid to increase the stability of the formulation have been studied. (3) Results: Maximum stability of combined doses was determined at pH 7.4, and maximum complexation at pH 8.0. Taking this into account, formulations presented the minimum dose of two active pharmaceutical ingredients dissolved. The addition of ascorbic acid at 0.1% w/v enables the detection of a higher remaining quantity of both drugs after three days of storage at 5 °C. (4) Conclusions: a formulation which combines the minimum paediatric dosages dissolved recommended by WHO for Isoniazid and Rifampicin has been developed. Future assays are needed to prolong the stability of the formulation with the aim of incorporating Pyrazinamide to the solution.

Chlorsulfuron Adsorption by Humic Acid, Iron Oxides, and Montmorillonite

Weed Science ◽  
1988 ◽  
Vol 36 (4) ◽  
pp. 530-534 ◽  
Author(s):  
Ole K. Borggaard ◽  
Jens C. Streibig
Keyword(s):  
Humic Acid ◽  
Surface Charge ◽  
Surface Area ◽  
Iron Oxides ◽  
Acidic Solution ◽  
Background Electrolyte ◽  
Acid Base ◽  
Weakly Acidic Solution ◽  
Ph Conditions ◽  
Soil Constituents

An investigation of the adsorption of chlorsulfuron by four selected soil constituents, i.e. humic acid, two iron oxides, and montmorillonite, was carried out under concentration and pH conditions similar to those in most natural soils. CaCl2(0.01 M) was used as background electrolyte to suppress nonspecific adsorption. Negligible amounts of chlorsulfuron were adsorbed by montmorillonite, whereas humic acid and the iron oxides were found to be important adsorbents. For these adsorbents, chlorsulfuron adsorption decreased when pH increased from 4 to 8, with little adsorption occurring at pH 8. Adsorption by iron oxides was a function of their surface area. Chlorsulfuron adsorption was found to be closely related to the surface charge of the adsorbents, but in weakly acidic solution, also to the acid-base properties of chlorsulfuron itself.

Synthesis of ZnO Nanoparticles by a Novel Gas Condensation System

2007 ◽  
Vol 364-366 ◽  
pp. 454-459
Author(s):  
Ho Chang ◽  
Ching Song Jwo ◽  
Tsing Tshih Tsung ◽  
Pei Shu Fan ◽  
Yan Chyuan Wu ◽  
...  
Keyword(s):  
Zno Nanoparticles ◽  
Average Diameter ◽  
Cold Trap ◽  
Momentum Exchange ◽  
Pure Zinc ◽  
Gas Condensation ◽  
Innovative System ◽  
Ph Conditions ◽  
The Stability ◽  
High Frequency Induction

This paper describes an innovative system to produce nanoparticles based on the theory of gas condensation in producing nanoparticles. In a vaccuum environment, the system used the energy produced by high frequency induction to vaporize a pure zinc rod inside the crucible. During the vaporization the chamber was filled with He gas, so the high-temperatured vaporized metal can undergo momentum exchange with He gas and at the same time, induce the vaporized metal to move to the cold trap. Upon reaching the wall of the cold condenser, the vaporized metal instantly condensed, forming nanoparticles. The TEM image shows that their average diameter was 30 nm, and the size was very consistent. In addition, the Zeta potential and average diameter of the ZnO nanofluid was also measured under different pH conditions to determine the stability of the ZnO nanofluid. Moreover, in order to verify the practicability of the fabricated ZnO nanoparticles, the ZnO nanofluid was inspected by UV/Vis absorption spectrum, and the results show that ZnO nanoparticles absorption ability was within a wavelength range from 350nm to 550nm.

Effect of manure colloid on stability and transport of titanium dioxide

2020 ◽  
Author(s):  
Jianying Shang ◽  
Chaorui Yan
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Quartz Sand ◽  
Organic Fertilizer ◽  
Dlvo Theory ◽  
Column Experiments ◽  
Colloidal Transport ◽  
Ph Conditions ◽  
Underlying Mechanisms ◽  
The Stability

<p>This study was to investigate the effect of different manure colloids on the stability and transport of TiO<sub>2</sub> NPs. Manure was used in fields as a common organic fertilizer. Different manure colloids were selected to study their effects on the aggregation and transport of nTiO<sub>2</sub> at neutral pH conditions. The absorbance and particle size of the nTiO<sub>2</sub> suspension at a certain ionic strength and manure colloid concentration were measured to determine the stability and aggregation of the nTiO<sub>2</sub> particles at pH 7. Column experiments were performed to examine colloidal transport in quartz sand under water condition similar to those used in stability tests. The interaction energy among the nTiO<sub>2</sub> particles and between nTiO<sub>2</sub> particle and quartz sand were calculated using the classical DLVO theory to elucidate the underlying mechanisms involved at pH 7. The results showed that manure colloids can promote the dispersion and transport of TiO<sub>2</sub> NPs under different conditions. </p>

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