The kinetics of oxidation of sodium sulphite

Srivastava, Ram; McMillan, Alan F.; Harris, I. J.

doi:10.1002/cjce.5450460308

Cited by 32 publications

(19 citation statements)

References 12 publications

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“…The higher the HSO 3 Ϫ concentration, the higher is the rate until the ceiling of the diffusional regime is reached. It is worth noticing that for low HSO 3 Ϫ concentration values, the Co 2ϩ -catalyzed reaction rate is far higher than the uncatalyzed rate. When the HSO 3 Ϫ concentration increases, experimental points asymptotically approach the uncatalyzed reaction line.…”

Section: Resultsmentioning

confidence: 99%

“…It is worth noticing that for low HSO 3 Ϫ concentration values, the Co 2ϩ -catalyzed reaction rate is far higher than the uncatalyzed rate. When the HSO 3 Ϫ concentration increases, experimental points asymptotically approach the uncatalyzed reaction line. Figure 3 shows the results obtained in the second set of experiments.…”

Section: Resultsmentioning

confidence: 99%

“…The first set of experiments was carried out to study the reaction rate as a function of HSO 3 Ϫ concentration at the temperature of 45°C and a fixed Co 2ϩ concentration ͑c Co 2ϩ ϭ 1 mol m Ϫ3 ). The second set includes experimental runs carried out at three different temperature levels (25,45, and 55°C) by varying catalyst concentration at fixed SO 2 and Ca(OH) 2 levels in feed solution.…”

Section: Resultsmentioning

confidence: 99%

“…The kinetics of these reactions (in particular, of oxygen absorption by solutions of calcium bisulfite) in the absence 2,3 and in presence 4 -6 of catalysts has been of great interest during the last 5 decades. The main engineering uses of sulfite (SO 3 2Ϫ ) oxidation are the determination of the interfacial area or the volumetric mass transfer constant in gas-liquid contactors and, recently, the oxidation of calcium sulfite waste products in FGD.…”

Section: Introductionmentioning

confidence: 99%

“…Lancia and co-workers 1 started by studying the bisulfite ion (HSO 3 Ϫ ) oxidation reaction in heterogeneous, absolute catalyst-free conditions, highlighting that calcium bisulfite oxidation rate is of zero order in oxygen and three halves in HSO 3 Ϫ .…”

Section: Introductionmentioning

confidence: 99%

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Sulfite Oxidation Catalyzed by Cobalt Ions in Flue Gas Desulfurization Processes

Karatza

Prisciandaro

Lancia

et al. 2010

Journal of the Air & Waste Management Association

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This paper presents an experimental study of calcium bisulfite oxidation, a key step in the wet limestonegypsum flue gas desulfurization (FGD) process, in the presence of catalysts (e.g., cobalt ions and a mixture of ferrous and cobalt ions). A fundamental approach is followed, by reproducing a simplified synthetic FGD liquor in which both catalyst ions, alone or mixed together, are present. A laboratory-scale apparatus is used, in which sulfurous solution is contacted with a gas phase at a fixed oxygen partial pressure (21.3 kPa) and at different temperature levels (25, 45, and 55°C). The experimental results are analyzed using the theory of gas-liquid mass transfer with chemical reaction, showing that the slow reaction regime is explored and the transition from the kinetic to the diffusional subregime is identified. The experimental results are compared with those obtained in the presence of other catalytic species (manganese and ferrous ions), showing that cobalt is effective in catalyzing the oxidation of calcium bisulfite to sulfate, but to a minor extent with respect to iron and manganese.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Sulfite Oxidation Catalyzed by Cobalt Ions in Flue Gas Desulfurization Processes

Karatza

Prisciandaro

Lancia

et al. 2010

Journal of the Air & Waste Management Association

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Simultaneous measurement of interfacial area and mass transfer coefficients for a well—mixed gas dispersion in aqueous electrolyte solutions

Robinson

Wilke

1974

AIChE Journal

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A new measuring technique involving concurrent chemical absorption of carbon dioxide and desorption of oxygen is developed for simultaneously evaluating the liquid-phase mass transfer coefficient k~, and the specific area a of sparingly-soluble gas dispersions in stirred tanks containing an aqueous solution of inorganic electrolytes. The method ensures that k L and a are evaluated under consistent hydrodynamic conditions.Results from three different nonviscous systems show that at high agitation power, such that the average bubble diameter is between 0.2 and 2 mm, k L decreases with increasing power input and is dependent on the bubble diameter. This behavior is in contrast to the results of others at lower agitation levels or in nonelectrolytic liquids, but in general agreement with previous results for bubbles of the same diameter range produced in viscous, nonelectrolytic solutions. In the absence of a sufficiently fast chemical reaction in the liquid phase, the gas absorption rate capability of a particular stirred tank design customarily has been characterized by the overall volumetric mass transfer coefficient KLa. It would seem preferable, however, to be able to predict K L u from separate correlations for its constituent parameters K L and a since their values are predominantly dependent upon distinctly different phyqicochemical parameters of the system. In previous studies k L has been shown both theoretically (Higbie, 1935; Danckwerts, 1951) and experimentally (Calderbank and Moo-Young, 1961) to be dependent primarily upon liquidphase diffusivity and viscosity. On the other hand, a is dependent primarily upon interfacial tension for pure liquids or nonelectrolyte solutions (Calderbank, 1958) or upon ionic strength in solutions of inorganic electrolytes exhibiting Newtonian rheological behavior (Robinson and Wilke, 1971). CAMPBELLDirect measurement of k L in stirred tank gas dispersions is not possible. However, given separate evaluations of K L u and a for sparingly soluble gases wherein the major resistance to mass transfer resides in the liquid phase, the liquid-phase mass transfer coefficient k, may be computed No general correlations for either JcL or a applicable to stirred tank gas dispersions in aqueous electrolyte solutions have yet been developed. The purpose of the present study was to develop and to conduct preliminary experimental tests of a new technique by means of which k L and a could be simultaneously evaluated under consistent physico-chemical and hydrodynamic conditions in aqueous electrolyte solutions having a wide variation in both composition and ionic strength.Experimentally, the new technique involves unsteady state desorption of oxygen from an aqueous electrolyte solution containing a controlled, low concentration of hydroxyl ion accompanied by concurrent, pseudo steady state absorption with chemical reaction of carbon dioxide from the sparged gas. The oxygen desorption rate is measured by a dissolved oxygen probe, the response of which, after correction for the diffusional l...

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Kinetics of oxidation of sodium dithionite by flow thermal method

1978

Self Cite

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The homogeneous kinetics and inhibition of sodium dithionite oxidation in an aqueous solution were studied by means of a flow thermal method. Results on the oxidation study of dithionite solutions at 3OoC show that the reaction is first order with respect to dithionite and zero order with respect to oxygen. An activation energy of 17.5 kcal/g-mole has been calculated for this reaction. The inhibiting effects of manganese chloride, manganese sulfate, and triethanolamine were inversely proportional to 0.8, 0.9, and 0.2 power, respectively.A free radical chain mechanism has been proposed, and the rate expres- Solutions nf sodium dithionite are used as powerful and rapid reducing agents for vat dyeing, bleaching, and for manufacture of various chemicals. The inherent instability of this compound with respect to atmospheric oxidation in aqueous solutions, however, lowers the efficiency of the solutions after prolonged storage. Therefore, a considerable excess of sodium dithionite over stoichiometric amounts must be used. It would be very desirable to minimize the excess consumption of sodium dithionite in industrial applications, and it is essentially in regard to this problem that the kinetics of sodium dithionite oxidation in aqueous solutions has been studied in some detail. The resulting information, however, is contradictory in many ways and thus remains inconclusive. The earliest oxidation study of dithionite was probably conducted by Meyer (1903); he computed first-order rate constants which drifted over a wide range. Nicloux (1933) and Lynn (1954) proposed an overall stoichiometry for the reaction. Lynn (1954) reported that the rate of atmospheric oxidation was first order, involving dithionite in solutions of 0.1M. Morello et al. (1964) reported that the reaction is first order with respect to dithionite and zero order with respect to molecular oxygen at operating concentrations between 8 )( 10-5 M and 47.5 X M dithionite and 10 X lop5 for oxygen. In contrast, Rinker et al. (1960) observed that the reaction is half order with respect to dithionite and first order with respect to oxygen. The pH of the reacting medium was held approximately at the value used by iMorello et al. Jhaveri and Sharma (1968) found the reaction to be first order with respect to dithionite for concentrations below 0.08 M/1 and second order for concentrations above 0.08 M/1. In the case of oxygen, the reaction was observed to proceed with zero order.The kinetic analysis has not been projected as a focal point because of the existing controversy in the experimental results. It should also be noted that substances such as manganese compounds, trialkanolamines, sodium phosphate, ammonium thiocyanate, etc. are known to inhibit the oxidation of sodium dithionite solutions; however, there seems to be no reported data on kinetics and inhibition. In the present investigation, the reaction rate of homogeneous liquid-phase oxidation of sodium dithionite solutions was studied by a flow-thermal method similar to that employed by Hartridge and Rou...

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The kinetics of oxidation of sodium sulphite

Cited by 32 publications

References 12 publications

Sulfite Oxidation Catalyzed by Cobalt Ions in Flue Gas Desulfurization Processes

Sulfite Oxidation Catalyzed by Cobalt Ions in Flue Gas Desulfurization Processes

Simultaneous measurement of interfacial area and mass transfer coefficients for a well—mixed gas dispersion in aqueous electrolyte solutions

Kinetics of oxidation of sodium dithionite by flow thermal method

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