scholarly journals Effects of pH on the stability of cyanidin and cyanidin 3-O-β-glucopyranoside in aqueous solution

2015 ◽  
Vol 69 (5) ◽  
pp. 511-522 ◽  
Author(s):  
Violeta Rakic ◽  
Mihaela Skrt ◽  
Milena Miljkovic ◽  
Danijela Kostic ◽  
Dusan Sokolovic ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Visible Range ◽  
Colour Intensity ◽  
Colour Variation ◽  
Acidic Solutions ◽  
Absorbance Maximum ◽  
Ph Values ◽  
Effects Of Ph ◽  
The Stability ◽  
Ph Range

The colour variation, colour intensity and stability at various pH values (2.0, 4.0, 7.0 and 9.0) of cyanidin 3-O-?-glucopyranoside (Cy3Glc) and its aglycone cyanidin was investigated during a period of 8 hours storage at 25?C. Our data showed that pH of aqueous solution had impact on spectroscopic profile of cyanidin and Cy3Glc. Beginning with the most acidic solutions, increasing the pH induce bathochromic shifts of absorbance maximum in the visible range for all examined pH values (with the exception pH 4.0 for cyanidin), while the presence of the 3-glucosidic substitution induce hypsochromic shift. Compared to cyanidin, Cy3Glc has higher colour intensity and higher stability in the whole pH range, except at pH 7.0. The 3-glucosidic substitution influences on the colour intensity of Cy3Glc in the alkaline region. After 8-hour incubation of Cy3Glc and cyanidin at pH 2.0 and 25 ?C, 99% of Cy3Glc and only 27% of cyanidin remained unchanged.

Schiff base equilibria. II. Beryllium complexes of N-n-butylsalicylideneimine and the hydrolysis of the Be2+ ion

1965 ◽  
Vol 18 (5) ◽  
pp. 651 ◽  
Author(s):  
RW Green ◽  
PW Alexander
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Complex Formation ◽  
Distribution Coefficient ◽  
Dilute Aqueous Solution ◽  
The Stability ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Beryllium Complexes ◽  
Equilibria In Aqueous Solution

The Schiff base, N-n-butylsalicylideneimine, extracts more than 99.8% beryllium into toluene from dilute aqueous solution. The distribution of beryllium has been studied in the pH range 5-13 and is discussed in terms of the several complex equilibria in aqueous solution. The stability constants of the complexes formed between beryllium and the Schiff base are log β1 11.1 and log β2 20.4, and the distribution coefficient of the bis complex is 550. Over most of the pH range, hydrolysis of the Be2+ ion competes with complex formation and provides a means of measuring the hydrolysis constants. They are for the reactions: Be(H2O)42+ ↔ 2H+ + Be(H2O)2(OH)2, log*β2 - 13.65; Be(H2O)42+ ↔ 3H+ + Be(H2O)(OH)3-, log*β3 -24.11.

scholarly journals An Investigation into the Adsorption of Aniline from Aqueous Solution Using H-Beta Zeolites and Copper-Exchanged Beta Zeolites

2005 ◽  
Vol 23 (3) ◽  
pp. 255-266 ◽  
Author(s):  
J. O'Brien ◽  
T. Curtin ◽  
T.F. O'Dwyer
Keyword(s):  
Aqueous Solution ◽  
Adsorption Process ◽  
Zeolite Beta ◽  
Langmuir Model ◽  
Beta Zeolite ◽  
Copper Leaching ◽  
Beta Zeolites ◽  
The Stability ◽  
Ph Range ◽  
Adsorbent Materials

Zeolite beta, a large-pore zeolite, was investigated in this study with a view to examining it as a potential adsorbent for the removal of aniline from aqueous solutions. Two different metal-loaded zeolites were prepared by exchanging H-beta zeolite (SiO2/Al2O3 = 75:1) with copper. The influence of exchanged copper on the uptake level was assessed. The effect of varying the silica-to-alumina ratio of the H-beta zeolite on the aniline uptake level was also examined, using three different H-beta zeolites with ratios of 25:1, 75:1 and 150:1 as adsorbents. The sorption experiments indicated an uptake level of ca. 110–120 mg/g for each zeolite and this level was also adsorbed by the copper-modified H-beta zeolites (SiO2/Al2O3 = 75:1). In all cases, the adsorption process followed the Langmuir model for adsorption and the level of aniline adsorbed was largely unaffected by a change in temperature or the presence of extra framework copper. The stability of the exchanged copper on these zeolites was then examined by measuring the quantity of copper leached from each zeolite into solution as a function of pH. Minimum copper leaching was observed in the pH range 5–11. This provided a stable pH working range for the adsorbent materials.

scholarly journals Effects of pH and Aeration on Sclerotium rolfsii sacc. Mycelial Growth, Sclerotial Production and Germination

2018 ◽  
Vol 7 (3) ◽  
pp. 123-129 ◽  
Author(s):  
Fakher Ayed ◽  
Hayfa Jabnoun-Khiareddine ◽  
Rania Aydi-Ben-Abdallah ◽  
Mejda Daami-Remadi
Keyword(s):  
Mycelial Growth ◽  
Sclerotium Rolfsii ◽  
Dry Weight ◽  
Ph Values ◽  
Effects Of Ph ◽  
Ph Range ◽  
Sclerotial Development ◽  
Sclerotial Germination

Sclerotium rolfsii is one of the devastating soilborne fungus responsible for significant plant losses. The effects of pH and aeration on pathogen mycelial growth, sclerotial production and germination were investigated for three Tunisian isolates. Optimal mycelial growth occurred at pH 6 for Sr2 and Sr3 isolates and at pH 6-7 for Sr1. Dry mycelial growth was optimum at pH values ranging between 4 and 7. Sclerotial initiation started on the 3rd day of incubation at all pH values tested and mature sclerotia were formed after 6 to 12 days. Optimal sclerotial production was noted at pH 5. The dry weight of 100 sclerotia varied depending on isolates and pH and occurred at pH range 4-7. At pH 9, mycelial growth, sclerotial production and dry weight of 100 sclerotia were restricted. The optimum sclerotial germination, noted after 24 h of incubation, varied depending on isolates and pH and occurred at pH 4-9. Mycelial growth was optimum in aerated plates with a significant isolates x aeration treatments interaction. Sclerotial initiation occurred at the 3rd day of incubation and mature sclerotia were observed after 6-9 days. Sclerotial development was very slow in completely sealed plates and dark sclerotia were produced only after 15 days of incubation. The highest sclerotial yields were noted in aerated plates. The highest dry weight of 100 sclerotia for Sr1 isolate was recorded in ½ sealed, no sealed and completely sealed plates, while for Sr2, it was noted in ½ and ⅔ sealed plates. For Sr3, the maximum dry weight of 100 sclerotia was recorded in ½, ⅔ and completely sealed plates. Germination of S. rolfsii sclerotia, after 24 h of incubation, did not vary significantly depending on aeration treatments and ranged from 90 to 100% for all isolates.

EFFECTS OF pH AND NITROGEN SOURCES ON GROWTH OF MICROCYSTIS AERUGINOSA KÜTZ.

1962 ◽  
Vol 8 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Jack McLachlan ◽  
P. R. Gorham
Keyword(s):  
Growth Inhibition ◽  
Microcystis Aeruginosa ◽  
Nitrate Nitrogen ◽  
Nitrogen Sources ◽  
Cesium Chloride ◽  
Potassium Nitrate ◽  
Degree Of Ionization ◽  
Ph Values ◽  
Effects Of Ph ◽  
Ph Range

Microcystis aeruginosa Kütz. (strain NRC-1) grew equally well throughout the pH range 6.5 to 10 when provided with suitable media. Toxicity of tris(hydroxymethyl)aminomethane (TRIS) towards the alga was found to decrease as the pH decreased and could be correlated with the degree of ionization of the TRIS molecule. Other organic buffers examined were either toxic at all concentrations and pH values tested or promoted lysis. When TRIS was used as a buffer, higher concentrations of cesium chloride and potassium nitrate were tolerated without growth inhibition at pH 6.5 than at 7.5. In the presence of TRIS, Microcystis grew equally well with nitrate, ammonium, or urea as nitrogen sources. Eight out of 20 amino compounds examined served as nitrogen sources in TRIS-buffered medium, but growth was poorer than with nitrate nitrogen.

scholarly journals Adsorption Properties of Sepiolite in Relation to Uranium and Lanthanide Ions

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 686 ◽  
Author(s):  
Gładysz-Płaska
Keyword(s):  
Adsorption Capacity ◽  
Adsorption Properties ◽  
Lanthanide Ions ◽  
Ambient Conditions ◽  
Initial Concentration ◽  
Ph Values ◽  
Batch Technique ◽  
Effects Of Ph ◽  
Ph Range

The batch technique was used to study the adsorption of La(III), Eu(III), Lu(III), and U(VI) ions on sepiolite and ODTMA–sepiolite under ambient conditions. The effects of pH, time, and initial concentration were investigated. The highest U(VI) adsorption was found on ODTMA-sepiolite in the pH range of 6–8, while in the case of lanthanide ions, adsorption on sepiolite was 80% in the pH range of 4–8 and 98% for pH values above 8. The adsorption capacity of ODTMAsepiolite was found to be 285.6 mg/g for uranium, and raw sepiolite: 142.8 mg/g for U(VI), 91.6 mg/g for La(III), 91.4 mg/g for Eu (III), and 104.9 mol/g for Lu(III). ODTMA–sepiolite turned out to be a weak sorbent for lanthanide ions. Two short- and long-lived fluorescence species were observed in the TRLFS spectra of U(VI) adsorbed on sepiolite at pH 6.5. The average lifetimes of short- (τ1) and long-lived (τ2) fluorescence are τ1 = 2420 ± 430 ns and τ2 = 37950 ± 5710 ns for U-sepiolite; τ1 = 3523 ± 160 ns and τ2 = 45400 ± 1830 ns for U-ODTMA–sepiolite.

Adsorption and desorption of boron by goethite

Soil Research ◽  
1987 ◽  
Vol 25 (4) ◽  
pp. 377 ◽  
Author(s):  
PM Bloesch ◽  
LC Bell ◽  
JD Hughes
Keyword(s):  
Elevated Temperature ◽  
Boron Concentration ◽  
Soil Testing ◽  
Adsorption And Desorption ◽  
Ph Values ◽  
Competing Anions ◽  
Effects Of Ph ◽  
Ph Range ◽  
Best Fit ◽  
Boron Adsorption

The effects of varying pH, concentration of boron, and competing anions on the adsorption of boron were examined. Boron adsorption initially increased with pH, peaked at approximately pH 8, and then declined. The presence of phosphate reduced adsorption over the pH range 5.2-10.6; the effect of sulfate was less than that of phosphate and ceased at about pH 7. The presence of mannitol caused virtually no difference in boron adsorption up to about pH 6, but reduced adsorption at higher values. The model by Bowden and coworkers was successful in describing both the charge characteristics of goethite in the absence of boron adsorption and the effects of pH and boron concentration on adsorption of the element. The best fit of the model was achieved when B(OH)4-, B3O3(OH)4-, B4O5(OH):- and B5O6(OH)4- were considered as the adsorbing species, although B(OH)4- and B4O5(OH)24- were predicted to be the major adsorbing ions. Boron adsorption was found to be reversible with respect to both concentration and pH. Elevated temperature increased the amount of desorption at both pH 6 and 8. The effect of mannitol on boron desorption mirrored the effect of the compound on adsorption of the element; there was no effect up to pH 6, but at higher pH values desorption was increased. The significance of the desorption data for soil testing for boron is discussed.

Impact of inorganic buffering ions on the stability of Fe(vi) in aqueous solution: role of the carbonate ion

2016 ◽  
Vol 18 (6) ◽  
pp. 4415-4422 ◽  
Author(s):  
Michal Kolář ◽  
Petr Novák ◽  
Karolína M. Šišková ◽  
Libor Machala ◽  
Ondřej Malina ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Carbonate Ion ◽  
The Stability ◽  
Ph Range

The study presents a systematic kinetics investigation of the decay of ferrate(vi) in the presence of inorganic buffering ions (borate, phosphate, and carbonate) at a pH range from 6.0 to 9.0.

scholarly journals Zinc adsorption in highly weathered soils

2008 ◽  
Vol 43 (1) ◽  
pp. 131-139 ◽  
Author(s):  
José Carlos Casagrande ◽  
Marcio Roberto Soares ◽  
Ernesto Rinaldi Mouta
Keyword(s):  
Ionic Strength ◽  
Ph Value ◽  
Batch Adsorption ◽  
Adsorption Mechanisms ◽  
Ionic Strength Effect ◽  
Ph Values ◽  
Effects Of Ph ◽  
Ph Range ◽  
Highly Weathered Soils ◽  
Zinc Adsorption

The objective of this work was to assess the effects of pH and ionic strength upon zinc adsorption, in three highly weathered variable charge soils. Adsorption isotherms were elaborated from batch adsorption experiments, with increasing Zn concentrations (0-80 mg L-1), and adsorption envelopes were constructed through soil samples reactions with 0.01, 0.1 and 1 mol L-1 Ca(NO3)2 solutions containing 5 mg L-1 of Zn, with an increasing pH value from 3 to 8. Driving force of reaction was quantified by Gibbs free energy and separation factor. Isotherms were C-, H- and L-type and experimental results were fitted to nonlinear Langmuir model. Maximum adsorption ranged from 59-810 mg kg-1, and Zn affinity was greater in subsoil (0.13-0.81 L kg-1) than in the topsoil samples (0.01-0.34 L kg-1). Zinc adsorption was favorable and spontaneous, and showed sharply increase (20-90%) in the 4-6 pH range. No effect of ionic strength was observed at pH values below 5, because specific adsorption mechanisms predominated in the 3-5 pH range. Above pH 5, and in subsoil samples, Zn was adsorbed by electrostatic mechanisms, since ionic strength effect was observed. Despite depth and ionic strength effects, Zn adsorption depends mainly on the pH.

Metal–Amino Polycarboxylic Acid Complexes. IV. A Polarographic Study of Lead (II) Complexes with Diethylenetriaminepentaacetic Acid in Aqueous Solution

1972 ◽  
Vol 50 (23) ◽  
pp. 3821-3831 ◽  
Author(s):  
P. Letkeman ◽  
J. B. Westmore
Keyword(s):  
Current Treatment ◽  
Lead Ion ◽  
Polycarboxylic Acid ◽  
Polarographic Behavior ◽  
Ph Values ◽  
Coordination Sites ◽  
Irreversible Reduction ◽  
Terminal Nitrogen Atom ◽  
The Stability ◽  
Ph Range

The polarographic behavior of the lead ion in the presence of excess DTPA was studied over the pH range 2–10. Three different polarographic waves can be distinguished. The wave occurring at the most negative potentials and highest pH values is assigned to an irreversible reduction of PbHA2−. The kinetic current treatment gives the results[Formula: see text]The wave occurring at intermediate potentials and pH values is also assigned to an irreversible reduction of PbHA2−. The kinetic current treatment gives the results[Formula: see text]Protonation is assumed to occur at different coordination sites. In the former case it occurs at the center carboxyl group; in the latter case it occurs at a terminal nitrogen atom. The reversible wave occurring at the most positive potentials and lowest pH values can be interpreted in either of two ways[Formula: see text]For the stability constant we obtained log KpbA = 19.1. All values above were obtained at 25° and an ionic strength of 0.2.

Effect of Different Washing Treatments on the Formation of Titanate Nanotubes

2010 ◽  
Vol 663-665 ◽  
pp. 1247-1251 ◽  
Author(s):  
Cheng Yan Liu ◽  
Lei Miao ◽  
Rong Huang ◽  
Sakae Tanemura
Keyword(s):  
Aqueous Solution ◽  
Driving Force ◽  
Deionized Water ◽  
Sodium Ion ◽  
Titanate Nanotubes ◽  
Acidic Solutions ◽  
Ph Values ◽  
Acid Washing ◽  
Almost All ◽  
Titanate Nanosheets

Titanate nanotubes were successfully synthesized by means of an alkaline hydrothermal method and further appropriate post-treatments. The effect of different washing treatments on the formation of titanate nanotubes were systematically studied in this paper. It was found that the washing treatments play an important role in the formation of nanotubes. Treating with 0.1M NaCl aqueous solution mainly resulted in titanate nanosheets while treating with deionized water or 0.1M HCl aqueous solution (1 time, PH>7) can obtain highly crystallized titanate nanotubes. Furthermore, if the PH values of solutions after acid washing processes were below 7, trace of nanotubes can be found but almost all of them were damaged. On the basis of all the present experimental results, we can conclude that titanate nanotubes can be prepared as long as the driving force induced by the imbalance of sodium ion (Na+) concentration on two different sides of nanosheets was appropriate, and meanwhile they were instable in acidic solutions.

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