Electrical conductivity sodium sulfate electrolytes

A new solid state chemical sensor for sulfur dioxide utilizing a sodium sulfate/rare earth sulfates/silicon dioxide electrolyte has been developed. The addition of rare earth sulfates and silicon dioxide to the sodium sulfate electrolyte was found to enhance the durability and electrical conductivity of the electrolyte. The electrolyte exhibits a Nernstian response in the range of SC gas concentrations from 30 ppm to 1 %. 

Other physical phenomena that may be associated, at least partially, with complex formation are the effect of a salt on the viscosity of aqueous solutions of a sugar and the effect of carbohydrates on the electrical conductivity of aqueous solutions of electrolytes. Measurements have been made of the increase in viscosity of aqueous sucrose solutions caused by the presence of potassium acetate, potassium chloride, potassium oxalate, and the potassium and calcium salt of 5-oxo-2-pyrrolidinecarboxylic acid.81 Potassium acetate has a greater effect than potassium chloride, and calcium ion is more effective than potassium ion. Conductivities of 0.01-0.05 N aqueous solutions of potassium chloride, sodium chloride, potassium sulfate, sodium sulfate, sodium carbonate, potassium bicarbonate, potassium hydroxide, and sodium hydroxide, ammonium hydroxide, and calcium sulfate, in both the presence and absence of sucrose, have been determined by Selix.88 At a sucrose concentration of 15° Brix (15.9 g. of sucrose/100 ml. of solution), an increase of 1° Brix in sucrose causes a 4% decrease in conductivity. Landt and Bodea88 studied dilute aqueous solutions of potassium chloride, sodium chloride, barium chloride, and tetra-... 

In our investigation, sodium sulfate was selected as the electrolyte. Rare earth sulfates Lj CSO, (LnsY and Gd) were added in order to increase the electrical conductivity. Silicon dioxide was ad ed so as to obtain the network structure which is effective for Na cation conduction and to prevent the electrolyte from becoming too soft. A thinner electrolyte was possible to prepare by mixing in SiC. The suppression of the phase transformation(15, 16) from Na2S0,-I(a high temperature phase) to Na2S0 -IH(a low temperature phase was also achieved by mixing rare earth sulfates(Ln=Y and Gd) and silicon dioxide into sodium sulfate. 

The discontinuity in the logfoT)-l/T relation which results from the phase transformation between HI to I, also appears in the Na2S0,-Si02 systems. The temperature at a break is nearly the same as the DTA result. Sodium sulfate mixed with SiC does not seem to be an appropriate solid electrolyte because of its low electrical conductivity and the presence of a transformation. 

In conclusion, the sodium sulfate mixed with rare earth sulfates (Ln=Y and Gd) and silicon dioxide exhibits high electrical conductivity and is more durable than the pure sodium sulfate. Furthermore, the Na-SO, -Y (S0, -SiO solid electrolyte ipaintains a similar phase to Na-oO -I, whicn is excellent in Na+ cation conduction. The measured EMf was in excellent accordance with the calculated EMF, at SO2 gas concentration in the range of 30 ppm to 1 %. In fact, the solid reference electrode method could be applicable as a practical SO2 gas detector. 

In alkaline sols small amounts of salts such as sodium sulfate accelerate gelling as the sol is dried. Since for strongest gel structure the sol must dry to the highest possible silica concentration before gelling occurs, it is evident that in alkali-stabilized sols, electrolytes should be avoided. For example, Reuter (229) claims as a binder a silica sol of small particles having a pH between 8.5 and 9, with a minimum of electrolyte, so that its electrical conductivity is due only to the colloidal particles and their stabilizing counterions and not to electrolyte impurities. 

Na and mean a sodium ion and vacancy at the grain boundary, respectively. This effect is caused by the interaction between the grains of electrolyte that disperse in fine grains of insulation material like y-Al203 and depends on the volume fraction and the grain size of the disper-soid. This effect is illustrated in Fig. 2. The addition of 40 mass% y-Al203 to sodium sulfate as well as to potassium sulfate provokes an increase in electrical conductivity. 

Aqueous solutions of sodium chloride and cupric sulfate of, say, 1 M concentration conduct electricity much better than a 1 M solution of acetic acid. This suggests that the sodium chloride and cupric sulfate exist in solution to a greater extent as ions than does acetic acid. More detailed investigations have indicated that certain substances, including sodium chloride and cupric sulfate, occur almost entirely as ions when in aqueous solution. Such substances are known as strong electrolytes. Other substances are present only partially as ions. Acetic acid, for example, exists in solution partly as CH3COOH and partly as CHaCOO"" -f These are known as weak electrolytes. 

Thermodynamic equilibria are also of principal importance, if one wishes to determine carbon dioxide or sulfur dioxide with carbonates or sulfates which show conductance for sodium or potassium ions. It is not the ion migrating through the solid, but the electrochemical equilibrium between molecules in the gas phase, particles in the solid electrolyte and electrons in the electrical conductor that determine the electrode potential utilizable in sensors. 

The name given to a substance which when dissolved in water enables the resulting solution to conduct an electric current. The most common electrolytes in the human body are salts of such minerals as sodium, potassium, magnesium, calcium, phosphate, sulfate, and chloride. 

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