Comprehensive Colorimetric Study of Anthocyanic Copigmentation in Model Solutions. Effects of pH and Molar Ratio

2012 ◽  
Vol 60 (11) ◽  
pp. 2896-2905 ◽  
Author(s):  
Belén Gordillo ◽  
Francisco J. Rodríguez-Pulido ◽  
M. Luisa Escudero-Gilete ◽  
M. Lourdes González-Miret ◽  
Francisco J. Heredia
Keyword(s):  
Molar Ratio ◽  
Model Solutions ◽  
Effects Of Ph ◽  
Colorimetric Study

scholarly journals Effects of pH and Ca/P molar ratio on the quantity and crystalline structure of calcium phosphates obtained from aqueous solutions

2009 ◽  
Vol 89 (3-4) ◽  
pp. 301-316 ◽  
Author(s):  
Omar Mekmene ◽  
Sophie Quillard ◽  
Thierry Rouillon ◽  
Jean-Michel Bouler ◽  
Michel Piot ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Crystalline Structure ◽  
Calcium Phosphates ◽  
Molar Ratio ◽  
Effects Of Ph

Study on Treatment of Ammonium Nitrogen in Desulfurization and Denitrification Wastewater with Sodium Hypochlorite

2013 ◽  
Vol 864-867 ◽  
pp. 438-441
Author(s):  
Zhen Zhou ◽  
Da Long Hu ◽  
Chu Qiao Zhang ◽  
Xue Lian Shen ◽  
Chun Hua Wu ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Sodium Hypochlorite ◽  
Ph Value ◽  
Ammonium Nitrogen ◽  
Molar Ratio ◽  
Distillation Method ◽  
Good Reliability ◽  
Initial Concentration ◽  
N Removal ◽  
Effects Of Ph

Based on the investigation of measurement method of ammonium nitrogen (NH4-N) desulfurization and denitrification wastewater (DDW) by distillation method, effects of pH, Cl/N and the initial concentration of NH4-N on the removal of NH4-N in DDW by sodium hypochlorite were studied. Results of parallel test and standard recovery test demonstrated good reliability and accuracy of the distillation method for the measurement of NH4-N in DDW. The NH4-N removal efficiency increased with pH from 5.0 and 8.0, and then decreased with pH higher than 8.0. Therefore, the optimum pH value was 8.0 with NH4-N removal efficiency of 74.7%. NH4-N removal efficiency was increased from 16.9% to 84.1% with Cl/N molar ratio rose from 1 to 5. The initial concentration of NH4-N showed insignificant effect on the removal amount of NH4-N, and the removed NH4-N was about 12~13mg/L with the addition of 4.86mmol/L sodium hypochlorite.

Functionalization of Mesoporous SBA-15 with APTES by Co-Condensation and its Effect on Immobilization of Candida rugosa Lipase

2015 ◽  
Vol 645-646 ◽  
pp. 1261-1266 ◽  
Author(s):  
Xiu Yan Li ◽  
Yun Qiang Xu ◽  
Guo Wei Zhou
Keyword(s):  
Electron Microscopy ◽  
Enzymatic Activity ◽  
Hydrothermal Process ◽  
Candida Rugosa ◽  
Molar Ratio ◽  
Surface Areas ◽  
Transmission Electron ◽  
Effects Of Ph ◽  
Loading Amount ◽  
Hydrolysis Of

Functionalized SBA-15 with mesoscopic pore channels was synthesized by co-condensation of tetraethoxysilane and (3-aminopropyl) triethoxysilane (APTES) via hydrothermal process. Small-angle X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy were used to monitor the effect of surface functionalization on the structural and textural features of the SBA-15. The results suggested that the structural ordering of functionalized SBA-15, as well as pore diameters, pore volumes and surface areas, were decreased with increasing the APTES molar ratio. Candida rugosa lipase (CRL) was used as a model enzyme for studying the effect of amino-functionalized on loading amount and enzymatic activity. The effects of pH and temperature on catalytic hydrolysis of tributyrin by immobilized CRL were investigated. The results showed that immobilized CRL had a well adaptability in a wide pH and temperature region, and CRL immobilized on functionalized SBA-15 exhibited much higher enzymatic activity than free CRL, especially, 5 mol% APTES functionalized SBA-15 immobilized CRL displayed the highest activity.

scholarly journals Deposition of Arsenic from Nitric Acid Leaching Solutions of Gold–Arsenic Sulphide Concentrates

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 889
Author(s):  
Kirill Karimov ◽  
Denis Rogozhnikov ◽  
Evgeniy Kuzas ◽  
Oleg Dizer ◽  
Dmitry Golovkin ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Acid Leaching ◽  
Elemental Sulphur ◽  
Seed Crystal ◽  
Effect Of Temperature ◽  
Molar Ratio ◽  
Lower Amount ◽  
Market Demand ◽  
Model Solutions ◽  
Nitric Acid Leaching

At present, the processing of refractory gold–arsenic sulphide concentrates is becoming more relevant due to the depletion of rich crude ore reserves. In the process of the nitric acid leaching of arsenic sulphide minerals, solutions are formed containing 20–30 g/L of arsenic (III). Since market demand for arsenic compounds is limited, such solutions are traditionally converted into poorly soluble compounds. This paper describes the investigation of precipitating arsenic sulphide from nitric acid leaching solutions of refractory sulphide raw materials of nonferrous metals containing iron (III) ions using sodium hydrosulphide with a molar ratio of NaHS/As = 2.4–2.6, which is typical for pure model solutions without oxidants. The work studied the effect of temperature, the pH of the solution and the consumption of NaHS and seed crystal on this process. The highest degree of precipitation of arsenic (III) sulphide (95–99%) from nitric acid leaching solutions containing iron (III) ions without seed occurs with a pH from 1.8 to 2.0 and a NaHS/As molar ratio of 2.8. The introduction of seed crystal significantly improves the precipitation of arsenic (III) sulphide. An increase in seed crystal consumption from 0 to 34 g/L in solution promotes an increase in the degree of transition of arsenic to sediment from 36.2 to 98.1% at pH = 1. According to SEM/EDS and XRF sediment data, from the results of experiments on the effect of As2S3 seed crystal consumption, acidity and molar ratio of NaHS/As on the precipitation of arsenic (III) sulphide and the Fetotal/Fe2+ ratio in the final solution, it can be concluded that the addition of a seed accelerates the crystallisation of arsenic (III) sulphide by increasing the number of crystallisation centres; as a result, the deposition rate of As2S3 becomes higher. Since the oxidation rate of sulphide ions to elemental sulphur by iron (III) ions does not change significantly, the molar ratio of NaHS/As can be reduced to 2.25 to obtain a precipitate having a lower amount of elemental sulphur and a high arsenic content similar to that precipitated from pure model solutions.

Magnesium phosphate crystallization in a fluidized-bed reactor: Effects of pH, Mg:P molar ratio and seed

2014 ◽  
Vol 125 ◽  
pp. 90-96 ◽  
Author(s):  
Chia-Chi Su ◽  
Lorenz Docena Dulfo ◽  
Maria Lourdes P. Dalida ◽  
Ming-Chun Lu
Keyword(s):  
Fluidized Bed ◽  
Fluidized Bed Reactor ◽  
Magnesium Phosphate ◽  
Molar Ratio ◽  
Effects Of Ph

scholarly journals Glutathione-Induced Conversion of Pentavalent Antimony to Trivalent Antimony in Meglumine Antimoniate

2001 ◽  
Vol 45 (3) ◽  
pp. 913-916 ◽  
Author(s):  
Frédéric Frézard ◽  
Cynthia Demicheli ◽  
Claúdio S. Ferreira ◽  
Michelle A. P. Costa
Keyword(s):  
Standard Treatment ◽  
Reduced Glutathione ◽  
Reduced Form ◽  
Molar Ratio ◽  
Dependent Manner ◽  
Acidic Ph ◽  
Meglumine Antimoniate ◽  
Pentavalent Antimony ◽  
Effects Of Ph ◽  
Dose Dependent

ABSTRACT The standard treatment of human leishmaniases involves the use of pentavalent antimony [Sb(V)] compounds, including meglumine antimoniate. The mode of action of these compounds has not been fully elucidated. The possibility that Sb(III) is involved has been suggested; however, the biomolecule that may induce the conversion of Sb(V) to Sb(III) has not yet been identified. In the present study, we investigated both the ability of reduced glutathione (GSH) to promote the reduction of Sb(V) into Sb(III) in meglumine antimoniate and the effects of pH and temperature on this transformation. GSH did promote the reduction of Sb(V) into Sb(III) in a dose-dependent manner. When GSH and meglumine antimoniate were incubated together at a GSH/Sb molar ratio superior or equal to 5:1, all antimony was encountered in the reduced form, indicating a stoichiometry of 5:1 between GSH and Sb(V) in the reaction. The reaction between Sb(V) and GSH was favored at an acidic pH (pH 5) and an elevated temperature (37°C), conditions found within the phagolysosome, in which Leishmania resides. For instance, about 30% of the Sb(V) (concentration, 2mM) was converted to Sb(III) following incubation for 3 days with 10 mM GSH at pH 5 and 37°C. Our data support the hypothesis that Sb(V) would be converted by GSH, or a related thiol compound, to more toxic Sb(III) in the phagolysosome of macrophages.

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