Rechargeability

Fuel cells involve use of gaseous reactants to produce electricity - most often H2-O2 within a porous electrode. Secondary cells are rechargeable. The most important systems are... 

If a solution of 18 g. of barium sulphate in one litre of concentrated sulphuric acid is employed, a precipitate of barium sulphate will form when sufficient water has been absorbed to render it un6t for drying recharging will then, of course, be necessary. 

About 150 ml. of concentrated sulphuric acid is placed in the larger funnel and 100 ml. of concentrated hydrochloric acid in the smaller separatory funnel. The latter is raised until the capillary tube is above the sulphuric acid, the capillary tube is filled with concentrated hydrochloric acid, and the stopper replaced. The rate of evolution of hydrogen chloride is controlled by regulation of the supply of hydro chloric acid this will continue until a volume of hydrochloric acid equal to that of the concentrated sulphuric acid has been used. The diluted sulphuric acid should then be removed and the apparatus recharged. The yield is 31-33 g. of hydrogen chloride per 100 ml. of concentrated hydro chloric acid. If more than an equal volume of hydrochloric acid is employed, the yield of gas decreases and continues to be formed for a tune after the stopcock has been closed. 

Acetylene is obtained from a cylinder (at ground level outside the fum chamber) and is freed from acetone by passing through two 500 ml. wash bottles, half filled with concentrated sulphuric acid, at the rate of 2-3 litres per minute when the acid in the second wash bottle becomes discoloured, the wash bottles should be recharged with fresh acid. The... 

After the block is chucked in the lathe, the lathe turns the block against the knife and peels the veneer in a continuous sheet as the knife moves toward the center of the block. When the knife cannot advance further without moving into the metal chucks, the lathe is stopped, the core of the block is dropped, the lathe is recharged, and the cycle repeated. 

Other applications of zirconium tetrafluoride are in molten salt reactor experiments as a catalyst for the fluorination of chloroacetone to chlorofluoroacetone (17,18) as a catalyst for olefin polymerization (19) as a catalyst for the conversion of a mixture of formaldehyde, acetaldehyde, and ammonia (in the ratio of 1 1 3 3) to pyridine (20) as an inhibitor for the combustion of NH CIO (21) in rechargeable electrochemical cells (22) and in dental applications (23) (see Dentalmaterials). 

Fig. 3. Three-dimeiisioiial flow for stream recharge via a water table aquifer where (a) is the elevation view and (b) is the plan view.

Hydrogen-storage alloys (18,19) are commercially available from several companies in the United States, Japan, and Europe. A commercial use has been developed in rechargeable nickel—metal hydride batteries which are superior to nickel—cadmium batteries by virtue of improved capacity and elimination of the toxic metal cadmium (see BATTERIES, SECONDARYCELLS-ALKALINe). Other uses are expected to develop in nonpolluting internal combustion engines and fuel cells (qv), heat pumps and refrigerators, and electric utility peak-load shaving. 

One of the problems with early hydride systems was decrepitation of the alloy. Each time the metal hydride storage tank was recharged the particles would break down and eventually the particles became so small that they began to pass through the 5-p.m sintered metal filter which kept the hydride inside the tank. Addition of 0.5% manganese, which caused the decrepitation process to cease once the particles reached a size of about 10 p.m, solved this problem. 

W. R. Mills, Jr., Orange County Water District Wasteirater Reclamation, Talbert Barrier and Recharge Project, Annual Report 91-121 for the California Regional Water QuaUty Control Board, Santa Ana Region, 1995. 

In many cases, the quality of a stream or another water source can be adequately improved by removing more BOD or suspended solids. In other iastances, the effluent is prepared for groundwater recharge which may require only the removal of nutrient. A classification of wastewater treatment processes is given ia Table 3. Table 4 summarizes water quality criteria for various iadustrial uses (10). 

Other alkaline primary cells couple zinc with oxides of mercury or silver and some even use atmospheric oxygen (zinc—air cell). Frequendy, zinc powder is used in the fabrication of batteries because of its high surface area. Secondary (rechargeable) cells with zinc anodes under development are the alkaline zinc—nickel oxide and zinc—chlorine (see Batteries). 

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