scholarly journals Effect of organic exudates of Phaeodactylum tricornutum on the Fe(II) oxidation rate constant

2012 ◽  
Vol 38 (1B) ◽  
pp. 245-261 ◽  
Author(s):  
AG González
Keyword(s):  
Rate Constant ◽  
Oxidation Rate ◽  
Phaeodactylum Tricornutum ◽  
Oxidation Rate Constant

Oxidation rate of elemental sulfur particles with a wide range of sizes

Soil Research ◽  
1993 ◽  
Vol 31 (1) ◽  
pp. 67
Author(s):  
JH Watkinson
Keyword(s):  
Rate Constant ◽  
Oxidation Rate ◽  
Total Mass ◽  
Elemental Sulfur ◽  
Sieve Analysis ◽  
Oxidation Rate Constant ◽  
Sieve Fraction ◽  
Wide Range ◽  
The Mean ◽  
Lower Size

An equation is proposed that describes the oxidation rate of elemental sulfur particles with a wide range of sizes, such as would be found in fertilizers. The only information needed is the mean oxidation rate constant over the period of interest and, from a sieve analysis, the proportions of the total mass in each sieve fraction (ratio of upper to lower size < to 2).

Corrigenda - Oxidation rate of elemental sulfur particles with a wide range of sizes

Soil Research ◽  
1993 ◽  
Vol 31 (1) ◽  
pp. 67
Author(s):  
JH Watkinson
Keyword(s):  
Rate Constant ◽  
Oxidation Rate ◽  
Total Mass ◽  
Elemental Sulfur ◽  
Sieve Analysis ◽  
Oxidation Rate Constant ◽  
Sieve Fraction ◽  
Wide Range ◽  
The Mean ◽  
Lower Size

An equation is proposed that describes the oxidation rate of elemental sulfur particles with a wide range of sizes, such as would be found in fertilizers. The only information needed is the mean oxidation rate constant over the period of interest and, from a sieve analysis, the proportions of the total mass in each sieve fraction (ratio of upper to lower size < to 2).

scholarly journals The conformation-independent QSPR approach for predicting the oxidation rate constant of water micropollutants

2017 ◽  
Vol 24 (35) ◽  
pp. 27366-27375 ◽  
Author(s):  
Erlinda V. Ortiz ◽  
Daniel O. Bennardi ◽  
Daniel E. Bacelo ◽  
Silvina E. Fioressi ◽  
Pablo R. Duchowicz
Keyword(s):  
Rate Constant ◽  
Oxidation Rate ◽  
Oxidation Rate Constant

The effect of binding ions on the oxidation of horse heart ferrocytochrome c

1979 ◽  
Vol 57 (5) ◽  
pp. 372-377 ◽  
Author(s):  
B. F. Peterman ◽  
R. A. Morton
Keyword(s):  
Ionic Strength ◽  
Rate Constant ◽  
Binding Sites ◽  
Oxidation Rate ◽  
Specific Binding ◽  
Electron Transfer Reaction ◽  
Oxidation Rate Constant ◽  
Binding Model ◽  
Ferrocytochrome C ◽  
Cacodylate Buffer

The effect of various specific binding ions on the rate of oxidation by potassium ferricyanide of electrodialyzed horse heart ferroeytochrome c was studied. The ionic strength was kept constant using Tris–cacodylate buffer, pH 7.0. Either the Tris or cacodylate ion was replaced by the binding ion studied. At an ionic strength of 0.194 M (24 °C), replacing cacodylate by chloride decreased the bimolecular oxidation rate constant from about 13.3 × 106 (Tris–cacodylate) to about 8.8 × 106 M−1 s−1 (Tris–chloride). Comparable decreases were found when cacodylate was replaced by phosphate or when Tris was replaced by potassium. When picrate replaced cacodylate (ionic strength 0.0485 M) a larger decrease was found, from about 5.2 × 107 to about 0.8 × 107 M−1 s−1. Data at intermediate ion concentrations were consistent with a simple cooperative binding model. The calculated association constants for chloride, potassium, and phosphate were in the range of 2–20 M−1, while for picrate it was 500 M−1. The data were consistent with one bound ion per ferroeytochrome c molecule, except for picrate, for which two binding sites were suggested. The results were interpreted by the hypothesis that the picrate ion binds near the solvent-exposed heme edge. The electron transfer reaction of ferricyanide was also presumed to take place through this region. The other ions probably bind at some distance from the heme edge and were suggested to exert their effect by perturbing the proteins' solvent shell. Consistent with this was the effect of replacing H2O by D2O which decreased the oxidation rate constant by about 50%.

scholarly journals Effects of the chemical characteristics and concentration of inorganic suspended solids on nitrification in freshwater

2017 ◽  
Vol 76 (11) ◽  
pp. 3101-3113
Author(s):  
Quynh Nga Le ◽  
Chihiro Yoshimura ◽  
Manabu Fujii
Keyword(s):  
Clay Minerals ◽  
Rate Constants ◽  
Oxidation Rate ◽  
Suspended Solids ◽  
Nitrification Rate ◽  
Chemical Characteristics ◽  
Ammonium Oxidation ◽  
Nitrite Oxidation ◽  
Oxidation Rate Constant ◽  
Positive Effect

Abstract The effect of inorganic suspended solids (ISS) on nitrification in freshwater samples has been described inconsistently and remains unclear. This study therefore investigated the effects of the chemical characteristics and concentration of ISS on the nitrification rate by focusing on Nitrosomonas europaea and Nitrobacter winogradskyi as the two most dominant nitrification species in freshwater. Batch-wise experiments were conducted using three chemically well-characterized ISS (i.e. the clay minerals montmorillonite, sericite, and kaolinite in the concentration range 0–1,000 mg L−1). The results show that the ammonium oxidation rate constant (kNH4) was significantly affected by the ISS type, whereas changes in the ISS concentration had an insignificant effect on kNH4, except for kaolinite. The highest kNH4 was observed in samples containing sericite (kNH4, 0.067 L mg−1 day−1), followed by samples containing montmorillonite (kNH4, 0.044 L mg−1 day−1). The ammonium oxidation rate was low in the control and kaolinite samples. Nitrite oxidation was enhanced in the presence of all types of ISS. The rate constants of ISS-mediated nitrite oxidation (kNO2, 0.13–0.21 L mg−1 day−1) were not significantly different among the three types of ISS, but kNO2 was significantly affected by ISS concentration. Overall, our study indicated various effects of the ISS type and concentration on nitrification and, in particular, a notable positive effect of sericite.

Calculation of Boundary Conditions between Internal and External Oxidation of Silicon or Chromium Containing Steels

2011 ◽  
Vol 696 ◽  
pp. 88-93 ◽  
Author(s):  
Shohei Nakakubo ◽  
Mikako Takeda ◽  
Takashi Onishi
Keyword(s):  
Boundary Condition ◽  
Diffusion Coefficient ◽  
Boundary Conditions ◽  
Oxygen Concentration ◽  
Internal Oxidation ◽  
Rate Equation ◽  
Oxidation Rate ◽  
Oxidation Rate Constant ◽  
External Oxidation ◽  
Diffusion Coefficient Of Oxygen

The boundary constants between internal and external oxidation of Si or Cr containing steels (Fe-Si alloys or Fe-Cr alloys) at 850°C were calculated in order to clarify the formation mechanism of fayalite scale (Fe2SiO4) or chromite scale (FeCr2O4), which can form as a “sub-scale” in Si or Cr containing steels. The diffusion coefficient of oxygen in the alloy, Do, and the oxygen concentration at the specimen surface, NO(s), which are constituents of the internal oxidation rate constant, (2DONO(s)/NB(O)n), were calculated for various oxidation conditions, and the rate equation for internal oxidation was derived. By comparing the calculated and measured values of (2DONO(s)/NB(O)n), we confirmed that the rate equation determined for internal oxidation was reasonable. The boundary condition between internal and external oxidation of Si or Cr containing steels (Fe-Si alloys or Fe-Cr alloys) at 850°C were also calculated by substituting the calculated values of DO and NO(s) into the rate equation.

Oxidation of nitrobenzene by ozone in the presence of faujasite zeolite in a continuous flow gas–liquid–solid reactor

2010 ◽  
Vol 62 (5) ◽  
pp. 1076-1083 ◽  
Author(s):  
J. Reungoat ◽  
J. S. Pic ◽  
M. H. Manéro ◽  
H. Debellefontaine
Keyword(s):  
Liquid Phase ◽  
Chemical Oxygen Demand ◽  
Transfer Coefficient ◽  
Rate Constant ◽  
Decomposition Rate ◽  
Oxidation Rate ◽  
Continuous Flow ◽  
Oxygen Demand ◽  
Decomposition Rate Constant ◽  
Faujasite Zeolite

This work investigates the oxidation of nitrobenzene (NB) by ozone in the presence of faujasite zeolite. Experiments were carried out in a gas–liquid–solid reactor were ozone transfer and NB oxidation took place at the same time. Three configurations of the reactor were compared: empty, filled with inert glass beads and filled with faujasite pellets. First, ozone transfer coefficient (kLa) and decomposition rate constant (kC) were determined for each configuration. In presence of solid, kLa was 2.0 to 2.6 times higher and kC was 5.0 to 6.4 times higher compared to the empty reactor. Then, the various configurations were evaluated in terms of NB removal and chemical oxygen demand (COD) decrease. The faujasite reactor showed higher removal of NB and decrease of COD compared to other configurations under the same conditions suggesting that the faujasite increases the oxidation rate of NB. Oxidation of NB in presence of faujasite also proved to be limited by the transfer of ozone from the gas to the liquid phase.

Influence of medium on the kinetics of oxidation of iron(II) ion with t-butyl hydroperoxide

2006 ◽  
Vol 60 (4) ◽  
Author(s):  
B. Mihaljević ◽  
D. Ražem
Keyword(s):  
Acid Concentration ◽  
Rate Constant ◽  
Oxidation Rate ◽  
Solvent Polarity ◽  
Solvent Mixture ◽  
Butyl Hydroperoxide ◽  
Ligand Type ◽  
Tert Butyl Hydroperoxide ◽  
Inner Sphere ◽  
Order Of Magnitude

AbstractThe oxidation of iron(II) with tert-butyl hydroperoxide was investigated in the absence of oxygen in water, methanol, and the dichloromethane—methanol solvent mixture (φr = 2:1). The oxidation rate depends on solvent polarity; measured in the presence of SCN− at constant 0.8 mmol dm−3 HCl, the rate constant increases with the polarity decrease passing from water and methanol to the dichloromethane—methanol solvent mixture. Further, in non-aqueous solutions at this acid concentration the rate constant was higher than the rate constant in the presence of Cl− only. The oxidation rate measured in the [FeCl]2+ complex in dichloromethane—methanol was slow in acidic medium and increased by decreasing the acid concentration. Approaching the physiological pH conditions the rate constant attained the value of an order of magnitude of 103 dm3 mol−1 s−1, while very little alteration of stoichiometry of the oxidation reaction was observed. The rate constant measured in the presence of Cl− strongly depends on electrolyte concentration at concentrations less than 0.5 mmol dm−3 HCl, both in MeOH and the solvent mixture. Based on these results, a possible mechanism of the influence of solvent, acidity, and ligand type on the rate constant is discussed. We assume that the oxidation proceeds by an inner-sphere mechanism considering that the breakdown of the successor inner-sphere complex forming reactive alkoxyl radicals is probably the rate-limiting step.

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