Primary electrolytes

Aqueous polysulflde solutions have been widely investigated as primary electrolytes in photoelectrochemical solar cells (PEC Chap. 5). The complexity of these solutions arising from the overlap of multiple chemical equilibria is well... 

The electrolytes Na", and Cl are second only to glucose in being the most frequently run hospital tests. Many clinical chemistry analyzers now contain an ISE module for electrolyte analysis. Most commonly the module will consist of a Na -glass electrode, a valinomycin/PVC electrode, a Ag/AgCl pellet or a quaternary ammonium ion/PVC electrode and a reference electrode. A selective electrode for the bicarbonate ion continues to elude workers in the field. An indirect measurement of HCOf must be made. The sample is usually reacted with acid to evolve carbon dioxide gas which is measured with a traditional Severinghaus type CO2 electrode. Alternatively, the sample is treated with base to convert HCO to CO3 and a carbonate ion-selective electrode is used In this manner, the complete primary electrolyte profile is obtained electrochemically. 

Primary electrolytic Alumina, carbon anodes, Fluoride, both gaseous Spent potliners... 

Patients with persistent or recurrent VF or PVT following antiarrhythmic administration should be assessed for underlying electrolyte abnormalities as a cause for their refractory arrhythmia. The primary electrolyte abnormalities associated with refractory ventricular arrhythmias include hyperkalemia, hypokalemia, and hypomagnesemia. 

However, the products which can be found in spent batteries reveal more complicated reactions involving the electrolyte. For instance, in cells with NH4CI as primary electrolyte, such products as MnOOH, Zn(NH3)2Cl2, Zn(OH)Cl can be found, whereas in cells with ZnCh the formation of MnOOH, Zn(OH)Cl, ZnCb.xZnO is possible. 

Pertcchnetatc and Tc(lV) could be more sensitively analyzed in acidic media in the presence of thiocyanate by adsorption stripping voltammetry at the hanging mercury drop electrode using the differential pulse mode. Determinations down to 5-fO " g Te per ml were feasible. An intense eurrent signal at -1.32 V vs SCE was observed if only technetium and thiocyanate were present in the solution. Larger quantities of salts, e.g. chlorides and sulphates, decreased the sensitivity of the method considerably. This, however, could easily be avoided if, after electrodeposition was completed, the primary electrolyte was replaced by a pure solution of dilute acid for the stripping voltammetric step [100]. 

Figure 3.2 Pourbaix diagram (potential vs. pH) of Ti in a solution containing 2.5 M ZnBr2 (primary electrolyte) and 0.9 M ZnCl2 (secondary electrolyte), indicating stability...

M ZnBt2 primary electrolyte, 1 M MEP and 10 g L of polyethylene glycol 6000 additive under a... 

Figure 5.5 Speciation diagram of ZnBr2 concentration versus pH for a ZnBr2 solution (primary electrolyte) containing 0.9 M ZnCl2 (supporting electrolyte), indicating...

Figure 5.8 Bromine half-cell Nyquist plot from potentiostatic EIS of a solution containing 2.5 M ZnBt2 primary electrolyte and 1 M MEP (This Nyquist plot was obtained by holding a working electrode at +1 V vs.

A potential-pH (Pourbaix) diagram for a 2.5 M ZnBra primary electrolyte solution was constmcted using OLl Studio software (version 9.2, OLl Systems, Inc.) and is presented in Fig. 2.2. 

Fig. 4.3 Scanning electron micrograph of zinc electrodeposited onto a graphite surface from a solution containing 2.5 M ZnBr2 primary electrolyte and 1 M MEP under a current density of 20 mA cm for 3 min...

The primary electrolyte imbalance associated with the hypovolemia, a loss of sodium (i.e., hyponatremia), may require sodium infusions until the underlying condition has been resolved. Since electrolytes may shift in response to sodium imbalances, other replacements may be indicated (see Chapter 5). 

The ZEBRA battery comprises a NiCU positive electrode in a central compartment with NaCl salt, impregnated with NaAlCls, which is a liquid mixture of NaCl and AICI3 (considered to be a secondary electrolyte). The negative electrode is liquid sodium confined in a second, outer compartment. The wall separating the two compartments is made of a P alumina ceramic (or P-AI2O3), conductive of sodium ions, considered to be the primary electrolyte. The element is sealed hermetically and functions at temperatures equal to or higher than 300°C so that the active components remain in the liquid state. 

Table W-4 lists ions which are found dissolved in the water of the body. Sodium, potassium, and chloride are the primary electrolytes which are most often discussed due to their important relationships in body fluids.

For cells with ammonium chloride as the primary electrolyte ... 

No freeze/thaw limitation— the thermally induced mechanical stress on the electrolyte is lower due to (a) the positive electrode is located inside of the electrolyte (b) a smaller difference exists between the solidification temperature of the positive electrode and ambient and (c) less mismatch in thermal expansion between the secondary and primary electrolyte. 

It need not be pointed out that in this example, as for all trace analyses, extremely pure chemicals must be used. Acetic acid is available in extremely pure form (Puranal, Suprapur). In chloride trace analysis special care must be given to the electrolyte contact between reference element and sample solution, since most reference half cells are filled with chloride-containing solutions. We will use a 0.1 M KQ solution as primary electrolyte for our Ag/AgCl reference electrode, and a KNO3 saturated 90% acetic acid solution for an outer electrolyte, which is to be renewed daily. In this way we have also made all provisions necessary for a constant liquid junction potential (see Sect. 2.3) ... 

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