Sulfur electrolyzer

Jayakumar JV, Guiiedge A, Staser JA et al (2012) Polybenzimidazoie membranes for hydrogen and sulfuric acid production in the hybrid sulfur electrolyzer. ECS Electrochem Lett 1 F44-F48... 

In another development (32), the sodium sulfate solution produced during the desulfurization of paste with caustic soda is electrolyzed in a membrane ceU to produce caustic soda and high purity sulfuric acid. The caustic soda is recycled to the desulfurization stage the sulfuric acid, after concentration, can be reused in battery production. 

The zinc electrolyte contains ca 60 kg/m zinc as sulfate and ca 100 kg/m free sulfuric acid. It is electrolyzed between electrodes suspended vertically in lead or plastic-lined, eg, poly(vinyl chloride), concrete tanks. The insoluble anodes are made of lead with small amounts of silver. The anodic... 

Another process, which also generates elemental sulfur as a by-product, has been patented by Envirotech Research Center in Salt Lake City (29). In the Electroslurry process, a ball mill finely grinds a chalcopyrite concentrate, which reacts with an acidic copper sulfate solution for iron removal. The Hquor is electrolyzed and the iron is oxidized to the ferric form. This latter step leaches copper from the copper sulfide for deposition on the cathode. Elemental sulfur is recovered at the same time. 

Elemental sulfur precipitates and is recovered. Copper powder is produced by electrolyzing the resulting solution. Developed by G. E. Atwood and C. H. Curtis of Duval Corporation at Tucson, AZ. See also Cymet. 

Ionics A flue-gas desulfurization process using aqueous sodium hydroxide. The resulting sodium sulfate solution is electrolyzed to yield sodium hydroxide, sodium bisulfate, sulfuric acid, oxygen, and hydrogen. 

Lacell A zinc extraction process in which zinc sulfide is converted to zinc chloride and molten sulfur, and the molten zinc chloride is electrolyzed. 

Lozano and Barba [82] electrolyzed 2-chloro-2-phenylacetyl chloride at mercury in methylene chloride and obtained derivatives of pyran-2-one and pyran-4-one, where R is H and C6H5CH2CO, respectively, at high and low current density (Scheme 6). In later work [83], the same workers reduced 2-bromo-2,2-diphenylacetyl bromide in methylene dichloride saturated with hydrogen sulfide gas three sulfur-containing... 

Tetraphenylarsonium pertechnetate is precipitated in the presence of perchlorate as the carrier. The mixed salts are disolved in concentrated sulfuric acid and the solution is electrolyzed at platinum electrodes. The black deposit (TcOj) obtained is dissolved in perchloric acid, technetium heptoxide is distilled out of the solution... 

Flagg and Bleidner electrolyzed carrier-free Tc -I- Tc on a platimun cathode in dilute sulfuric acid and obtained a 99.5% yield at —0.8 V vs. the saturated calomel electrode (SCE.). 

The reversible potential for the sulfur dioxide electrolysis is only 0.17 V, less than 10% that of water electrolysis (minimum of 1.23V at 298K and 1 bar) [65,69]. However corrosion problems in the electrolysis step are severe due to the presence of high concentration (about 50%) sulfuric acid. The overall thermal efficiency of the process, considering both thermal and electrical energy input derived from the same heat source, is estimated as 48.8% [116]. However, in terms of economics and process complexity the hybrid cycles face tough competition from advanced water electrolyzers. 

Cadmium also may be recovered from zinc ores and separated from other metals present as impurities by fractional distillation. Alternatively, the cadmium dust obtained from the roasting of zinc ore is mixed with sulfuric acid. Zinc dust is added in small quantities to precipitate out copper and other impurities. The metal impurities are removed by filtration. An excess amount of zinc dust is added to the solution. A spongy cadmium-rich precipitate is formed which may he oxidized and dissolved in dilute sulfuric acid. Cadmium sulfate solution is then electrolyzed using aluminum cathodes and lead anodes. The metal is deposited at the cathode, stripped out regularly, washed and melted in an iron retort in the presence of caustic soda, and drawn into desired shapes. More than half of the world s production of cadmium is obtained by elecrolytic processes. 

When the sulfide ore carroUite, CuS C02S3, is the starting material, first sulfides are separated by flotation with frothers. Various flotation processes are applied. The products are then treated with dilute sulfuric acid producing a solution known as copper-cobalt concentrate. This solution is then electrolyzed to remove copper. After the removal of copper, the solution is treated with calcium hydroxide to precipitate cobalt as hydroxide. Cobalt hydroxide is filtered out and separated from other impurities. Pure cobalt hydroxide then is dissolved in sulfuric acid and the solution is again electrolyzed. Electrolysis deposits metallic cobalt on the cathode. 

In general, copper metal is extracted from its ores by various wet processes. These include leaching with dilute sulfuric acid or complexing with ligands (e.g., sahcylaldoximes), followed by solvent extraction. The solution is then electrolyzed to refine copper. 

Iron and aluminum precipitate out when treated with ammonia and are removed by filtration. Other metals, such as copper, zinc, lead and arsenic are precipitated and removed as sulfides upon passing hydrogen sufide through the solution. Colloidal particles of metaUic sulfides and sulfur are removed by treatment with iron(ll) sulfide. The purified solution of manganese(ll) sulfate is then electrolyzed in an electrolytic cell using lead anode and HasteUoy or Type 316 stainless steel cathode, both of which are resistant to acid. Manganese is deposited on the cathode as a thin film. 

In another industrial process, flue dusts from smelting lead and zinc concentrates are boiled in acidified water. Thallium dissolves and is separated from insoluble residues by filtration. Dissolved thallium in solution then is precipitated with zinc. Thallium is extracted from the precipitate by treatment with dilute sulfuric acid which dissolves the metal. The solution may also contain zinc, cadmium, lead, copper, indium, and other impurities in trace amounts. These metals are precipitated with hydrogen sulfide. The pure thallium sulfate solution then is electrolyzed to yield thallium. 

Zinc also may be produced by electrolysis of zinc sulfate solution. The zinc oxide in the roasted concentrate is leached with sulfuric acid. The oxide is converted to soluble zinc sulfate. Impurity metals, such as iron, copper, cadmium, arsenic, tin, and cobalt are removed by precipitation, floe formation, and other methods. The purified zinc sulfate solution is electrolyzed using aluminum cathodes and lead anodes. Zinc is deposited on the cathode. 

Water is electrolyzed in the presence of a small amount of sulfuric acid or sodium sulfate added to water to provide ion flow in a solution. 

An aqueous solution of 0.1 M sulfuric acid is electrolyzed between two electrodes, which can be made of platinum, gold, or graphite. The electrodes are 1... 

Electrolytic Process—in which oxidized zinc concentrates are leached in sulfuric acid and then electrolyzed to plate SHG (special high-grade zinc metal) on the cathode and to regenerate the add on the anode. 

Figure 11.16 Schematic of copper recovery by coupled transport from dump leach streams. The concentrated copper solution produced by coupled transport separation of the dump leach liquid is sent to an electrolysis cell where copper sulfate is electrolyzed to copper metal and sulfuric acid...

Fluorine, F2 (mp, -218°C bp, -187°C), is a pale yellow gas produced from calcium fluoride ore by first liberating hydrogen fluoride with sulfuric acid, then electrolyzing the HF in a 4 1 mixture with potassium fluoride, KF, as shown in the reaction... 

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