OXYGEN EVOLUTION FROM SODIUM HYPOCHLORITE SOLUTIONS

1962 ◽  
Vol 40 (4) ◽  
pp. 729-733 ◽  
Author(s):  
M. W. Lister ◽  
R. C. Petterson
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Oxygen Evolution ◽  
Rate Constant ◽  
Sodium Hypochlorite ◽  
Chloride Ions ◽  
Effect Of Temperature

The rates of oxygen evolution from carefully purified solutions of sodium hypochlorite have been measured. Methods of purification are described, and it is found that substantially the same rate is observed regardless of the method of purification. The rate of oxygen evolution is proportional to the square of the concentration of hypochlorite ions. The effect of temperature and ionic strength are examined. The rate constant is 7.5 × 10−6 (g-mol/I.)−1(min)−1 at 60 °C and an ionic strength of 3.5; the activation energy is 26.6 kcal/g-mol. These results are compared with the corresponding quantities for the reaction of hypochlorite ions to form chlorite and chloride ions, and some tentative explanations are offered.

THE REACTION BETWEEN CYANATE AND HYPOCHLORITE

1956 ◽  
Vol 34 (4) ◽  
pp. 489-501 ◽  
Author(s):  
M. W. Lister
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Rate Constant ◽  
Hypochlorous Acid ◽  
Effect Of Temperature ◽  
Slow Step ◽  
True Activation Energy ◽  
Rate Of Reaction ◽  
Different Temperatures ◽  
Kinetics Of

The reaction between sodium hypochlorite and potassium cyanate in the presence of sodium hydroxide has been examined. The main products are chloride, and carbonate ions and nitrogen; but, especially if much hypochlorite is present, some nitrate is formed as well. The rate of reaction is proportional to the cyanate and hypochlorite concentrations, but inversely proportional to the hydroxide concentration: the rate constant is 5.45 × 10−4 min.−1 at 65 °C, at an ionic strength of 2.2. The rate constant increases somewhat as the ionic strength rises from 1.7 to 3.5. The effect of temperature makes the apparent activation energy 25 kcal./gm-molecule. The kinetics of the reaction suggest that the slow step is really a reaction of hypochlorous acid and cyanate ions, and possible intermediate products of this reaction are suggested. Allowing for the different extent of hydrolysis of hypochlorite at different temperatures, the true activation energy is found to be 15 kcal./gm-mol., which is consistent with the observed rate of reaction.

SOME OBSERVATIONS ON CYANIC ACID AND CYANATES

1955 ◽  
Vol 33 (2) ◽  
pp. 426-440 ◽  
Author(s):  
M. W. Lister
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Rate Constant ◽  
Ionization Constant ◽  
Side Reaction ◽  
Cyanic Acid ◽  
First Order ◽  
Second Stage ◽  
Carbonate Concentration ◽  
Considerable Range

Various reactions of cyanic acid and the cyanate ion have been examined. Cyanic acid, in the presence of added hydrochloric or nitric acid, decomposes quantitatively according to the equation: HNCO + H3O+ → CO2 + NH4+. The rate constant for this reaction was measured over a range of temperature and ionic strength, and was found to be 0.86 mole liter−1 min.−1 at unit ionic strength and 1.5 °C. The activation energy is [Formula: see text] The effect of ionic strength on the reaction with hydrochloric acid closely parallels that on the activity coefficients of the acid itself. Without added acid cyanic acid decomposes by a first order reaction: HNCO + 2H2O → NH4HCO3, followed by a rapid second stage: NH4HCO3 + HNCO → NH4NCO + H2CO3. This reaction has a rate constant of 0.011 min.−1 at 0 °C. and an activation energy of 16 kcal. There is also a few per cent of some side reaction. Cyanate ions in alkaline solution decompose thus: OCN− + 2H2O → NH4+ + CO3−−. This reaction was examined over a range of temperature and ionic strength: it is first order with k = 3.0 × 10−3 min.−1at 100 °C. (0.3 ionic strength) and [Formula: see text] activation energy. The rate is somewhat dependent on hydroxide concentration, when this is fairly low. The reaction is catalyzed by carbonate, but not by a number of other anions that were examined. The rate of the catalyzed reaction is proportional to the carbonate concentration, but independent of cyanate, at least over a considerable range. The ionization constant of cyanic acid has been measured by a method that avoids errors from hydrolysis; the value obtained was 2.0 × 10−4. The oxidation of cyanate by hypochlorite and by chlorine was examined more briefly.

scholarly journals Kinetic and Thermodynamic Study of Oxidative Decolourisation of a Typical Food Dye (Tartrazine) in an Aqueous Environment

2020 ◽  
Vol 24 (6) ◽  
pp. 1021-1026
Author(s):  
F.O. Okeola ◽  
E.O. Odebunmi ◽  
M.A. Amoloye ◽  
H.F. Babamale ◽  
S. Thema ◽  
...  
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Rate Constant ◽  
Metal Ion ◽  
Reaction Medium ◽  
Order Rate Constant ◽  
Aqueous Environment ◽  
Food Dye ◽  
Typical Food ◽  
Homogenous Catalyst

The study was carried out to describe the kinetics and thermodynamics of hydrogen peroxide oxidation of a typical food dye (Tartrazine). The effect of different operational factors were investigated spectrophotometricallyat wavelength460 nm under pseudo first order reaction.These included concentration of the oxidant and the dye, the pH, ionic strength and temperature of the reacting medium and the presence of transition metal ion as homogenous catalyst. A complete and smooth decolourisation was observed. The results showed that the rate of oxidation of dye increased with increasing in concentration of substrate and oxidant. Increasing in temperature, ionic strength and pH of the basic reaction medium also raised the reaction rate. The rate of oxidation also increased with increasing in the concentration of Fe (III) ion. Pseudo second order rate constant (k2) obtained was 1.95 x 10-3 M-1s-1 and 3.8 x10-3M-1s-1 in the absence and presence of Fe (III) ion respectively. The Arrhenius activation energy for the oxidation in the absence and presence of Fe (III) ion were 47.23 kJmol-1 and 42kJmol-1 respectively. Other thermodynamic parameters showed entropy of activation (ΔS#), free energy of activation (ΔG#) and Enthalpy of activation of the reaction (ΔH#) in the presence of Fe (III) as -34.7  JK-1mol-1, 48.4 kJmol-1 and 40.30 kJmol-1 respectively. The results in the absence of Fe (III) ion were -24.6 JK-1mol-1, 51.2 kJmol-1 and 44.0 kJmol-1respectively. The relative lower activation energy (Ea),fairly higher negative value of (ΔS#) and higher (ΔG#) , with higher rate constant in the presence of Fe(III) ion showed Fe(III) ion enhancement of rate of decolourisation. Keywords: Tartrazine Food dye, Kinetics, Thermodynamics, Hydrogen Peroxidede colourisation,

scholarly journals Study on drying kinetics of summer onion

2015 ◽  
Vol 39 (4) ◽  
pp. 661-673 ◽  
Author(s):  
Md Masud Alam ◽  
Md Nurul Islam ◽  
Md Nazrul Islam
Keyword(s):  
Activation Energy ◽  
Mass Transfer ◽  
Rate Constant ◽  
Variable Temperature ◽  
Air Flow ◽  
Drying Kinetics ◽  
Effect Of Temperature ◽  
Drying Rate ◽  
External Resistance ◽  
Kinetics Of

The present study was concerned with the kinetics of drying of summer onion. Drying was done in a mechanical dryer at constant air flow using blanched and unblanched onion with variable temperature (52, 60 and 680C) and thickness (3, 5 and 7 mm). Drying rate was increased with increase of temperature and decreased with the increase in thickness in blanched and unblanched onion. Blanched onion showed higher drying rate than unblanched onion. Drying rate constant and thickness can be expressed as power low equations. The value of index “n” were found to be 1.277 and 0.845 for onion indicating that the external resistance to mass transfer was highly significant. The effect of temperature on diffusion co-efficient follows an Arrhenius type relationship. The activation energy (Ea) for diffusion of water was found 5.781 Kcal/g-mole for unblanched and 2.46 Kcal/g-mole for blanched onion when onions were dried in mechanical dryer. DOI: http://dx.doi.org/10.3329/bjar.v39i4.22545 Bangladesh J. Agril. Res. 39(4): 661-673, December 2014

Reduction of chlorothallium(III) complexes by arsenic(III)

1973 ◽  
Vol 26 (10) ◽  
pp. 2115 ◽  
Author(s):  
PD Sharma ◽  
YK Gupta
Keyword(s):  
Ionic Strength ◽  
Acid Solution ◽  
Rate Constant ◽  
Perchloric Acid ◽  
Intermediate Formation ◽  
Chloride Ions ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Perchloric Acid Solution ◽  
Hydrogen Ion Concentration

The oxidation of arsenic(III) by thallium(III) in perchloric acid solution is inhibited by chloride ions. The reactivity of various chlorothallium(III) species is in the order Tl3+ > TlCl2+ > TlCl2+ > TlCl3 > TlCl4-. The rate decreases by increasing the hydrogen ion concentration and ionic strength. The redox process occurs by intermediate formation of a complex of thallium(III) and arsenic(III). The rate constant for the reaction between Tl3+ and arsenic(III) calculated from the data of the present investigation compared well with that of the reaction1 in the absence of chloride ions.

DECOMPOSITION OF SODIUM HYPOCHLORITE: THE UNCATALYZED REACTION

1956 ◽  
Vol 34 (4) ◽  
pp. 465-478 ◽  
Author(s):  
M. W. Lister
Keyword(s):  
Sodium Chloride ◽  
Ionic Strength ◽  
Rate Constant ◽  
Sodium Hypochlorite ◽  
Rate Constants ◽  
Bimolecular Reaction ◽  
Activation Energies ◽  
Unimolecular Reaction ◽  
Uncatalyzed Reaction ◽  
Catalytic Effects

The decomposition of sodium hypochlorite has been re-examined. The results show that Foerster and Dolch’s mechanism of the decomposition to chlorate and chloride is correct; they postulated a slow bimolecular reaction to chlorite and chloride, followed by a faster reaction of chlorite with more hypochlorite. Values of the rate constants of both steps are reported; they make the activation energies 24.8 kcal./gm-molecule for the first step and 20.8 kcal./gm-molecule for the second. The rates are such that at 40 °C. a solution of sodium hypochlorite will contain about 1% as much chlorite as hypochlorite. The rate is strongly affected by changing ionic strength; at low ionic strengths it is nearly constant or falls slightly; above about 0.8, the rate rises and at high ionic strengths the rise is quite rapid. No signs of specific catalytic effects of sodium chloride, hydroxide, or carbonate could be observed, and it seems probable that earlier reports of this were due to variations in ionic strength. The decomposition to chloride and oxygen has been measured and is a unimolecular reaction, which is possibly, but not certainly, uncatalyzed. Values of its rate constant are reported; they also are much altered by changing the ionic strength.

Sorption of Cadmium and Lead by Chelating Ion Exchangers Ostsorb OXIN, Ostsorb DETA, and Ostsorb DTTA

1994 ◽  
Vol 59 (6) ◽  
pp. 1311-1318 ◽  
Author(s):  
Ladislav Svoboda ◽  
Petr Vořechovský
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Sodium Perchlorate ◽  
Exchange Capacity ◽  
Chloride Ions ◽  
Point Of View ◽  
Alkaline Media ◽  
Ion Exchangers ◽  
Acidic Media ◽  
Cadmium And Lead

The properties of cellulose chelating ion exchangers Ostsorb have been studied in the sorption of cadmium and lead from aqueous solutions. The Cd(II) and Pb(II) ions are trapped by the Ostsorb OXIN and Ostsorb DETA ion exchangers most effectively in neutral and alkaline media but at these conditions formation of stable hydrolytic products of both metals competes with the exchange equilibria. From this point of view, Ostsorb DTTA appears to be a more suitable sorbent since it traps the Pb(II) and Cd(II) ions in acidic media already. Chloride ions interfere with the sorption of the two metals by Ostsorb DTTA whereas the ionic strength adjusted by the addition of sodium perchlorate does not affect the exchange capacity of this ion exchanger.

THE OXIDATION OF NITRITE AND IODATE IONS BY HYPOCHLORITE IONS

1961 ◽  
Vol 39 (8) ◽  
pp. 1645-1651 ◽  
Author(s):  
M. W. Lister ◽  
P. Rosenblum
Keyword(s):  
Activation Energy ◽  
Aqueous Solution ◽  
Rate Constant ◽  
Hypochlorous Acid ◽  
Slow Stage ◽  
Iodate Ions

The oxidation of nitrite ions and of iodate ions by hypochlorite ions in aqueous solution has been examined. The oxidation of nitrite is really a reaction of hypochlorous acid, with the slow stage HOCl + NO2− + H2O → H3O+ + Cl− + NO3−. The rate constant is given by log k = 7.36−6450/RT (time in minutes, and the activation energy in calories). The oxidation of iodate is chiefly a reaction of hypochlorite ions, probably ClO− + IO3− → Cl− + IO4−, although the rate is somewhat increased by a higher concentration of hydroxide ions. The rate constant is given by log k = 16.15−26,100/RT. These results are compared with other oxidations by hypochlorite ions, to see if any general trends are apparent.

scholarly journals Photocatalytic Degradation of Textile Dyeing Wastewater Using Titanium Dioxide and Zinc Oxide

2008 ◽  
Vol 5 (2) ◽  
pp. 219-223 ◽  
Author(s):  
Abbas J. Attia ◽  
Salih H. Kadhim ◽  
Falah H. Hussein
Keyword(s):  
Activation Energy ◽  
Zinc Oxide ◽  
Titanium Dioxide ◽  
Photocatalytic Degradation ◽  
Irradiation Time ◽  
Effect Of Temperature ◽  
Dyeing Wastewater ◽  
Textile Dyeing ◽  
Textile Factory ◽  
Textile Dyeing Wastewater

Photodegradation of a real textile dyeing wastewater taken from Hilla textile factory in Babylon Governorate, Iraq have been investigated. Photocatalytic degradation was carried out over suspensions of titanium dioxide or zinc oxide under ultraviolet irradiation. Photodegradation percentage was followed spectrophometrically by the measurements of absorbance at λmax equal to 380 nm. The rate of photodegradation increased linearly with time of irradiation when titanium dioxide or zinc oxide was used. A maximum color removal of 96% was achieved after irradiation time of 2.5 hours when titanium dioxide used at 303K and 82% color reduction was observed when zinc oxide used for the same period and at the same temperature. The effect of temperature on the efficiency of photodegradation of dyestuff was also studied. The activation energy of photodegradation was calculated and found to be equal to 21 ± 1 kJ mol-1 on titanium dioxide and 24 ± 1 kJ mol-1 on zinc oxide.

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