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Density NaCl + NaOH

Anode performance depends on the brine quality and the operating parameters such as pH, current density, NaCl concentration, and NaOH concentration (in diaphragm and membrane cells). The contribution of the anode to the cell inefficiency, as mentioned in Section 4.4, is directly related to the losses arising from the oxygen evolution reaction, and indirectly by chlorate formation. Thus, as the %02 increases, the pH at the anode-solution interface decreases, and hence, the amount of chlorate formed will decrease as the bulk pH is lowered. The amount of O2 generated at the anode is a function of the current density, pH, the composition and surface area of the anode coating, and the salt concentration. [Pg.224]

D. Caustic (Quality in NaOH vs KOH Systems. Chloride and chlorate levels in the caustic are expected to be lower during the electrolysis of KCl as compared to the NaCl system because of the lower water transport number of 2 to 3 during KCl electrolysis [96] compared to 4 during NaCl electrolysis. Calculations using the water transport number only showed the CP and CIOJ levels in the KOH product to be about 2 to 3 ppm, still exhibiting a dependency on current density, temperature, and anolyte concentration. This influence should be cautiously interpreted since the > aoj and K values in the calculations are those for the NaCl/NaOH system and not for the KCl/KOH system for which relevant data are not available. [Pg.339]

B The assumptions include no heat loss to the surroundings or to the calorimeter, a solution density of 1.00 g/mL, a specific heat of 4.18 J g 1 °C 1, and that the initial and final solution volumes are the same. The equation for the reaction that occurs is NaOH(aq) + HCl(aq) - NaCl(aq) + H20(l). Since the two reactants combine in a one to one mole ratio, the limiting reactant is the one present in smaller amount. [Pg.126]

Figure 19.9 shows the dependence of NaCl and NaCl03 in the 32% NaOH produced upon the current density value. A value of 3 ppm NaCl in 32% NaOH was measured as a remarkable quality of caustic soda at 7kA m-2. [Pg.257]

The concentration of the 0.25N NaOH was selected because it has equivalent conductivity to the 3.5% NaCl solution. The initial current levels in the NaCl Versus NaOH tanks were different despite the equivalent conductivities and the equal applied potential. The difference was due to the difference in pH. The more basic solution reduced the exchange current density for the hydrogen reaction. At this potential, the principal reaction is the hydrogen reaction. [Pg.173]

All ALP products absorbed more oil than the soy products. Acetone treatment of ALP resulted in reduced fat absorption ALP with higher lipid contents absorbed more oil. ALP extracted with water and NaOH absorbed more oil than those extracted with NaCl or Tris buffer. These researchers (19) attribute fat absorption to physical entrapment a correlation of 0.95 was found between fat absorption and bulk density. However, more oil was absorbed by the ALP than the soy products even though the products had similar bulk densities. [Pg.193]

Following such treatment, the cultured cells in monolayer are washed with phosphate-buffered saline and extracted in 4 ml 0.5% Triton X-100 in saline/EDTA (100 mM NaCl, 10 mM EDTA, pH 8.0) for 2 min at room temperature. This releases most of the cytoplasmic material whilst the nuclei remain attached to the culture dish. 0.5% sodium dodecyl sulphate and 40 //g/ml pancreatic RNAse (preincubated at 80°C for 10 min, to inactivate DNAse) in saline/EDTA (above) is then added and the mixture incubated for 20 min at 37°C. One volume of chloroform/isoamyl alcohol (20 5, v/v) is then added and the phases mixed gently. The aqueous phase is separated by centrifugation and extracted again with chloroform/isoamyl alcohol. DNA is precipitated from the aqueous phase with 2 vol 95% ethanol and resuspended in 0.01 M Tris, pH 7.5. Alkaline sucrose density gradients (5-20%) are prepared in 0.1 M NaCl, 0.1 M NaOH with a final volume of 4.1 ml. Samples of DNA (max 3 fig) are layered on the top of these gradients and spun at 32 000 rpm at 20°C in a SW.50.1 Beckman rotor for 120 min. Fractions are collected and the [3H]DNA precipitated... [Pg.244]

For assessing the viability and accuracy of high-temperature potentiometric measurements, the reference systems should be used. If Pt(H2) or YSZ(Hg/HgO) electrodes are used as the indicator electrodes, an aqueous solution with well-known activity of H+ (aq) should be used as the reference systems. At temperatures below 250 °C, the dilute aqueous solutions of strong acids and bases, such as HCl(aq) or NaOH(aq), can be employed to precisely calculate the activity of H+ (aq) so that the measured potential can be compared with the calculated one within a few millivolts or less. If HCl(aq) or NaOH(aq) is to be used at temperatures above 250 °C, the association constants of the electrolytes should be taken into account. Furthermore, at these temperatures, the precision of the calculated activities of H+ (aq) can be decreased. However, even in the low-density, supercritical aqueous solution, a reference system, which consists of a couple of three-component aqueous solutions, can be found to test the accuracy of the Pt(H2) or YSZ(Hg/HgO) electrodes within about 3 mV. Each of the three-component aqueous solutions consists of NaCl and either HC1 or NaOH... [Pg.736]

Measurements were performed using 2, 3, and 4 M NaCl anolyte and 8, 10, 12, and 14 M NaOH catholyte solutions. The cell temperature was varied between 80° and 90°C and membrane current density was varied between 3 and 8 kA m-2 to test the effect of these parameters on membrane performance. For a given temperature and current density, values of tNa+ were used to create a performance surface, using... [Pg.145]

For the application of these membranes to the electrolytic production of chlorine-caustic, other performance characteristics in addition to membrane conductivity are of interest. The sodium ion transport number, in moles Na+ per Faraday of passed current, establishes the cathode current efficiency of the membrane cell. Also the water transport number, expressed as moles of water transported to the NaOH catholyte per Faraday, affects the concentration of caustic produced in the cell. Sodium ion and water transport numbers have been simultaneously determined for several Nafion membranes in concentrated NaCl and NaOH solution environments and elevated temperatures (30-32). Experiments were conducted at high membrane current densities (2-4 kA m 2) to duplicate industrial conditions. Results of some of these experiments are shown in Figure 8, in which sodium ion transport number is plotted vs NaOH catholyte concentration for 1100 EW, 1150 EW, and Nafion 295 membranes (30,31). For the first two membranes, tjja+ decreases with increasing NaOH concentration, as would be expected due to increasing electrolyte sorption into the polymer, it has been found that uptake of NaOH into these membranes does occur, but the relative amount of sorption remains relatively constant as solution concentration increases (23,33) Membrane water sorption decreases significantly over the same concentration range however, and so the ratio of sodium ion to water steadily increases. Mauritz and co-workers propose that a tunneling process of the form... [Pg.61]

Figure 9. Current efficiency vs. NaOH catholyte concentration for Nafion 227 membrane in a chlor-alkali cell (34). Conditions current density, 31 A/dm2 temperature, 85° C anolyte concentration, 4.4 N NaCl cell voltage, 4.6 V. Figure 9. Current efficiency vs. NaOH catholyte concentration for Nafion 227 membrane in a chlor-alkali cell (34). Conditions current density, 31 A/dm2 temperature, 85° C anolyte concentration, 4.4 N NaCl cell voltage, 4.6 V.
A commercially available ED stack with bipolar, anion and cation membranes was used by the author to generate 1 N HCl and NaOH from NaCl. A current density of 100 mA/cm2 was maintained with an applied potential of 2V/cell. [Pg.494]

Figure 4.8 Current efficiency versus fixed ion concentration of a cation exchange membrane in the electrolysis of a sodium chloride solution. Cation exchange membrane sulfonated styrene—divinylbenzene type. Anolyte saturated NaCl catholyte 3.0 N NaOH current density 10Adm 2 at 70 °C. Figure 4.8 Current efficiency versus fixed ion concentration of a cation exchange membrane in the electrolysis of a sodium chloride solution. Cation exchange membrane sulfonated styrene—divinylbenzene type. Anolyte saturated NaCl catholyte 3.0 N NaOH current density 10Adm 2 at 70 °C.
A bipolar membrane in an electric field generates hydrogen ions on one side and hydroxyl ions on the other side. Therefore electrodialysis with a bipolar membrane can be used to produce acid and base from salt. For splitting 0.1 N NaCl at a current density i=20-150 A/sq. m concentrations of NaOH and HCl (C NaOH Cuch equiv./l) may be expressed as ... [Pg.283]

TABLE 4.6.5 Comparison of Hydrogen Overvoltage on Metals/Coatings in 15% NaOH + 17% NaCl at 95°C at a Current Density of 200 mA cm ... [Pg.260]

Chloride concentrations are typically less than 50 ppm (as NaCl on 50% NaOH basis). The chloride content decreases as current density increases, electrolyzer temperature decreases, caustic concentration increases, or anolyte concentration increases. During current interruptions, the rate of chloride diffusion through a membrane is about five times higher than during operation. Cooling the electrolyzer is the most effective way to reduce the diffusion of chloride ions during shutdowns. These measures are also helpful in controlling the chlorate levels in the catholyte. [Pg.350]

A typical chlorine production plant using membrane cells is pictured in Fig. 9.8. Electrolysers are operating at atmospheric pressure and 85°C.The main electrochemical characteristics of brine electrolysis cells using membranes are (i) operating current density 300-500 mA.cm (ii) cell voltage 3.0-3.6 V (iii) NaOH concentration 33-35 wt% (iv) energy consumption 2600-2800 kWh/ton Clj at 500 mA.cm (v) efficiency 50% and (vi) steam consumption for concentrating NaOH to 50% 180 kWh/ton CI2. The production of one ton of chlorine requires -1.7 tons of NaCl and less than 1 ton of water vapour. [Pg.399]


See other pages where Density NaCl + NaOH is mentioned: [Pg.85]    [Pg.14]    [Pg.489]    [Pg.175]    [Pg.83]    [Pg.353]    [Pg.76]    [Pg.654]    [Pg.736]    [Pg.264]    [Pg.471]    [Pg.414]    [Pg.656]    [Pg.1776]    [Pg.1776]    [Pg.1777]    [Pg.489]    [Pg.436]    [Pg.280]    [Pg.246]    [Pg.345]    [Pg.1501]    [Pg.106]    [Pg.2709]    [Pg.1022]    [Pg.315]    [Pg.1138]    [Pg.142]    [Pg.200]    [Pg.287]   
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