Influence of pH and Synthesis Duration on the Composition and Thermal Behavior of Hydrolysis Products of Lanthanum Nitrate

2019 ◽  
Vol 946 ◽  
pp. 150-155
Author(s):  
Viacheslav V. Avdin ◽  
Tatyana V. Mosunova ◽  
Artem V. Bogdanov
Keyword(s):  
Thermal Decomposition ◽  
Lanthanum Oxide ◽  
Lanthanum Nitrate ◽  
Ph Values ◽  
Carbonate Ions ◽  
Hydrolysis Products ◽  
Three Stages ◽  
Oxide Matrix ◽  
Influence Of Ph ◽  
Synthesis Duration

The study investigates the hydrolysis products of lanthanum nitrate, obtained at various pH values and times of the hydrolytic agent addition. It has been found that the structure formation of lanthanum oxyhydroxide is accompanied by capturing the admixture ions, namely, the anions of the reactant salt and carbonate ions. It has been shown that thermal decomposition of the hydrolysis products proceeds in four stages for faster hydrolysis. If hydrolysis is slow, the intervals merge together into three stages of thermal decomposition. The hydrolysis products of lanthanum nitrate, heated up to 500...550 С, actually consist of lanthanum oxide containing nitrate and carbonate, chemically bonded to the oxide matrix, in its inner regions. The composition of the synthesized samples changes if pH varies. The minimal content of admixture ions can be observed at the synthesis pH > 10, if the time of the hydrolytic agent addition equals 24 h. The obtained results suggest that lanthanum nitrate can be used as a precursor for synthesis of structured lanthanum oxide.

Synthesis, Characterization and Thermal studies of Novel Organomercury Driven from Sulfa Drugs Part 1

2011 ◽  
Vol 7 (2) ◽  
pp. 1338-1347
Author(s):  
Tarek Ali Fahad ◽  
Shaker.A.N. AL-Jadaan
Keyword(s):  
Thermal Decomposition ◽  
Thermal Behavior ◽  
1H Nmr ◽  
Elemental Analysis ◽  
Thermal Studies ◽  
Spectroscopic Techniques ◽  
Sulfa Drugs ◽  
Acid Base ◽  
Ph Values ◽  
Multi Stage

Two new heterocyclic Organmercury compounds   were prepared from the reaction of Sulfamethaxazole and Sulfadiazine with 4-acetaminophenol as a coupler and separated as solids with characteristic colors. these compounds were characterized by F.T.IR-spectroscopy 1H-NMR , Micro-elemental Analysis and UV-Vis spectroscopic techniques . The work involves a study of acid – base properties compounds at different pH values, the ionization and protonation constants were calculated. The thermal behavior of these two compounds   were investigated on the basis of thermogravimetric (TGA) and differential thermogravimetric (DTG) analyses, Thermal decomposition of these compounds is multi-stage processes.

scholarly journals The Influence of pH Values on the Crystallite Size of ZnO by Solvothermal Synthesis

2017 ◽  
Vol 2 (2) ◽  
pp. 118 ◽  
Author(s):  
Ahmadi Jaya Permana ◽  
Dian Wulandari ◽  
Hartati Hartati ◽  
Harsasi Setyawati ◽  
Mochammad Zakki Fahmi
Keyword(s):  
Heat Treatment ◽  
Zinc Oxide ◽  
Crystallite Size ◽  
Solvothermal Synthesis ◽  
Solvothermal Method ◽  
Ph Value ◽  
Semiconductor Material ◽  
X Ray ◽  
Ph Values ◽  
Influence Of Ph

 Zinc oxide (ZnO) is a semiconductor material that widely used in various applications due to its unique properties. Synthesis of ZnO by solvothermal method has been conducted with controlled pH values. The variations of pH value were 10, 11 and 12 by adjusting NaOH content. Crystall structure of the synthesis products after heat treatment at 110oC and 600oC has characterised by X-ray Diffratometer (XRD). Crystallite size of ZnO was measured by Scherrer equation. Crystall phase of ZnO has been observed on all pH value variations at 110 oC with 22,98-37,06 nm of crystallite size, whereas ZnO has been observed on all pH value variations at 600 oC with 41,39-71,77 nm of crystallite size.Keywords: ZnO, pH values, crystallite size, solvothermal

Proteolysis of αs1-casein by chymosin: influence of pH and urea

1977 ◽  
Vol 44 (3) ◽  
pp. 533-540 ◽  
Author(s):  
D. M. Mulvihill ◽  
P. F. Fox
Keyword(s):  
Aqueous Solution ◽  
The State ◽  
Ph Values ◽  
Influence Of Ph ◽  
Hydrolysis Of

SummaryThe specificity of chymosin on αs1-casein was shown to be dependent on the reaction pH and on the state of aggregation of the substrate. In aqueous solution αs1-casein was optimally hydrolysed to αs1-I at pH 5·8; if the casein was solubilized in the isoelectric region by the use of 5 M-urea, optimum proteolysis occurred at pH 2·8. Hydrolysis of αs1-I to yield αs1-II, αs1-III and αs1-IV occurred at pH values > 5·8 in the presence or absence of urea. In the isoelectric region αs1-II, αs1-III and αs1-IV were not formed in the absence of urea where the substrate was aggregated: instead a peptide αs1-V was produced; at the same pH and using urea as a solubilizing agent αs1-II, αs1-III and αs1-IV were formed together with a further peptide αs1-VI.

scholarly journals Organic/Inorganic Superabsorbent Hydrogels Based on Xylan and Montmorillonite

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Shuang Zhang ◽  
Ying Guan ◽  
Gen-Que Fu ◽  
Bo-Yang Chen ◽  
Feng Peng ◽  
...  
Keyword(s):  
Compressive Modulus ◽  
Cross Linking ◽  
Swelling Properties ◽  
Ph Values ◽  
Swelling Capacity ◽  
Wide Ph Range ◽  
Grafting Copolymerization ◽  
Ph Range ◽  
Influence Of Ph ◽  
Superabsorbent Hydrogels

The unique organic/inorganic superabsorbent hydrogels based on xylan and inorganic clay montmorillonite (MMT) were prepared via grafting copolymerization of acrylic acid (AA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) withN,N-methylenebisacrylamide (MBA) as a cross-linking agent and potassium persulfate (KPS) as an initiator. The effect of variables on the swelling capacity of the hydrogels, such as the weight ratios of MMT/xylan, MBA/xylan, and AMPS/AA, was systematically optimized. The results indicated that the superabsorbent hydrogels comprised a porous cross-linking structure of MMT and xylan with side chains that carry carboxylate, carboxamide, and sulfate. The hydrogels exhibit the high compressive modulus (E), about 35–55 KPa, and the compression strength of the hydrogels increased with an increment of the MMT content. The effect of various cationic salt solutions (LiCl, CaCl2, and FeCl3) on the swelling has the following order: Li+> Ca2+> Fe3+. Furthermore, the influence of pH values on swelling behaviors showed that the superabsorbent composites retained around 1000 g g−1over a wide pH range of 6.0–10.0. The xylan-based hydrogels with the high mechanical and swelling properties are promising for the applications in the biomaterials area.

Histamine and Tyramine Production by a Lactobacillus Strain Subjected to External pH Decrease

1994 ◽  
Vol 57 (3) ◽  
pp. 259-262 ◽  
Author(s):  
RIITTA MAIJALA
Keyword(s):  
Lactic Acid ◽  
Room Temperature ◽  
Lactobacillus Strain ◽  
Ph Values ◽  
Initial Ph ◽  
Ph Decrease ◽  
In The Beginning ◽  
Influence Of Ph ◽  
External Ph ◽  
Made In

The preservative effect of fermentation is based on the pH decrease during processing. However, most studies conceming the influence of pH on the formation of biogenic amines have been made in broths with different initial pH values. A histamine- and tyramine-positive Lactobacillus strain isolated from dry sausage was added at an initial level of 3.9- to 4.4-logl0 CFU/ml and incubated on a shaker at room temperature (20.0°C) for 6 days. The pH was decreased in histidine- or tyrosine-fortified MRS broth by adding glucono-delta-lactone (GDL) or lactic acid during the incubation. The external acidification decreased the growth and the production of histamine and tyramine by the strain. GDL was more effective as a preventative than lactic acid. According to these results, a rapid pH decrease resulting in decreased growth of amine-positive lactic acid bacteria in the beginning of fermentation may be a means of preventing the formation of high levels of amines in foods.

Influence of pH on the Formation of Glucan byLactobacillus reuteriTMW 1.106 Exerting a Protective Function Against Extreme pH Values

2008 ◽  
Vol 22 (4) ◽  
pp. 398-418 ◽  
Author(s):  
Susanne B. Kaditzky ◽  
Jürgen Behr ◽  
Andreas Stocker ◽  
Peter Kaden ◽  
Michael G. Gänzle ◽  
...  
Keyword(s):  
Protective Function ◽  
Ph Values ◽  
Influence Of Ph

Influence of pH on the Morphology and Luminescence Properties of Europium-Doped Hydroxyapatite Nanoparticles

2011 ◽  
Vol 391-392 ◽  
pp. 1132-1137
Author(s):  
Su Ping Huang ◽  
Jun Zhu ◽  
Ke Chao Zhou
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Doping Concentration ◽  
Ph Value ◽  
Luminescence Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Inductively Coupled ◽  
Ph Values ◽  
Influence Of Ph

Luminescence behaviors and morphology of Eu3+doped hydroxyapatite synthesized under different pH values were well investigated by X-ray diffraction (XRD), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Inductively Coupled Plasma (ICP) (ICP–PLASMA 1000), and photoluminescence (PL) spectroscopy. Results revealed that With pH values increased from 6.5 to 10.0, the morphology of nano-Eu:HA particles changes from rod particles to equiaxed particles. The actual doping concentration and aspect ratio of Eu3+-doped HA decreased with the increasing of pH value. At the same time, the fluorescence intensity also tends to weakly lower with the increasing of pH value, which indicated that the luminescence properties mainly depended on the actual Eu3+doping concentration, the influences of morphology on the luminescence properties were slight.

Two novel mixed Eu3+/Y3+ Ln MOFs: influence of pH on the topology, Eu/Y ratio and energy transfer

CrystEngComm ◽  
2014 ◽  
Vol 16 (25) ◽  
pp. 5681-5688 ◽  
Author(s):  
Yu Zhang ◽  
Weiwei Ju ◽  
Xiao Xu ◽  
Yun Lv ◽  
Dunru Zhu ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Ph Value ◽  
Ph Values ◽  
Influence Of Ph

Two mixed europium–yttrium MOFs with different interesting structures and doping proportions have been successfully synthesized by adjusting the pH values. The pH value largely affects the topologies and Eu/Y ratios of the two compounds.

Sign in / Sign up

Export Citation Format

Share Document