Reuse electrolyte

About 250 ml of a reaction mixture obtained by the electrolytic reduction of nitrobenzene in sulfuric acid solution and containing about 23 grams of p-aminophenol by assay is neutralized while at a temperature of 60° to 65°C, to a pH of 4.5 with calcium carbonate. The calcium sulfate precipitate which forms is filtered off, the precipitate washed with hot water at about 65°C and the filtrate and wash water then combined. The solution is then extracted twice with 25 ml portions of benzene and the aqueous phase is treated with 0.5 part by weight, for each part of p-aminophenol present, of activated carbon and the latter filtered off. The activated carbon is regenerated by treatment with hot dilute caustic followed by a hot dilute acid wash, and reused a minimum of three times. 

Recycling of the electrolyte from used, damaged, or faulty batteries and reuse in new stacks have gained considerable attention. The electrolyte is an essential constituent from the technical and economic viewpoint, showing extraordinary stability and no ageing effects. 

Primary metals manufacturing operations have experienced source reduction and recycle/reuse benefits similar to those available to metal finishing operations, including conserving waters through countercurrent rinsing techniques, and utilizing electrolytic recovery, customized resins, selective membranes, and adsorbents to separate metal impurities from acid/caustic dips and rinsewaters to thereby allow for recycle and reuse. 

Electrolytic refining does produce wastewaters that must be treated and discharged, reused, or disposed in some manner. Many facilities use a wastewater treatment operation to treat these wastes. 

One approach to waste reduction is to recover process materials for reuse. Materials used in metal finishing processes can be effectively recovered using available technologies such as dragout, evaporation, reverse osmosis, ion exchange, electrodialysis, and electrolytic recovery.22-26... 

There are advantages to the electrolytic recovery process. For instance, ER units can operate continuously, and the product is in a metallic form that is very suitable for reuse or resale. Electrolytic units are also mechanically reliable and self-operating. Very importantly, contaminants are not recovered and returned to the plating bath. Thus, electrolytically recovered metals are as pure as virgin plating raw material. 

Something more the magnesium-air cells possess an infinite shelf life because the electrolyte can be removed easily before storage. When power is needed, the electrolyte is poured back into the cell. No other electrochemical energy sources do exist in which the electrolyte can be removed, stored and reused by the consumer. 

Chemelec cell BEWT (Water Engineers) Ltd Vertical mesh (or plate) in an electrolyte with fluidized glass beads Discontinuous by manual scraping or reuse as anodes in plating No V ... 

An electrochemical reaction needs the transfer of ions between the electrodes. Therefore, the solution in the cell requires usually at least minimal ion conductivity. In most cases, a supporting electrolyte has to be added, and after the reaction it is separated and reused. 

The advantages of the electrolytic method is that silver is recovered in an almost pure form, making it easier to handle and less costly to refine. With careful monitoring, it also permits fixer reuse for some processes. It also avoids the need to store and replace cartridges, as with the... 

Recycling of wastes is the preferable waste management method after source reduction opportunities have been exhausted. Recycling can be performed within the process itself, within the plant, or off-site, and can involve reuse of the entire waste stream, or recovery of a part of it. Recovery of the stream s metal content can be achieved through operations such as electrolytic recovery, reverse osmosis, and ion exchange. 

The most popular method of silver recovery is electrolytic deposition. In an electrolytic recovery unit, a low voltage direct current is created between a carbon anode and stainless steel cathode. Metallic silver plates onto the cathode. Once the silver is removed, the fixing bath may be able to be reused in the photographic development process by mixing the desilvered solution with fresh solution. Recovered silver is worth about 80% of its commodity price. Used silver films also constitute a significant quantity of waste. The film can be sold for silver recovery to many small recyclers. 

Electrolytic recovery converts the toxic metals in solution into their nonhazardous elemental form. The positively charged metal ions, attracted to the negatively charged cathodes, are reduced at the cathodes where they plate out as sheet metal or pcwder. At Aeroscientific, planar cathodes are used, producing metal sheets that can be easily removed by simply flexing the cathodes. The sheets of metal can then be conveniently stored, transported, and disposed of. The cathodes can be reused. 

However, it can be assumed for most electrochemical applications of ionic liquids, especially for electroplating, that suitable regeneration procedures can be found. This is first, because transfer of several regeneration options that have been established for aqueous solutions should be possible, allowing regeneration and reuse of ionic liquid based electrolytes. Secondly, for purification of fiesh ionic liquids on the laboratory scale a number of methods, such as distillation, recrystallization, extraction, membrane filtration, batch adsorption and semi-continuous adsorption in a chromatography column, have already been tested. The recovery of ionic liquids from rinse or washing water, e.g. by nanofiltration, can also be an important issue. 

Despite the huge number of publications dealing with the application of ionic liquids, there are only a couple that include reuse aspects. To the best of our knowledge, there is none that deals with regeneration of spent ionic liquid based electrolytes. The intention of this contribution is to bridge this gap and suggest potential concepts for ionic liquid regeneration. 

Recovery, Regeneration and Reuse of Electrolytes in Electroplating II.4.2.1 The Concept... 

The overall concept for recovery, regeneration and reuse in electroplating is shown in Figure 11.17. It includes the recovery stage, in which the workpieces are rinsed for further cleaning and the diluted electrolyte received. The diluted solution... 

Other unit operations that have been established for aqueous solutions could be considered, to allow regeneration and reuse of ionic liquid based electrolytes. 

Despite the conspicuous advantages of the presented water-based regeneration approach, it is still to be shown whether it can be transferred to other tasks and whether the reuse of the regenerates in plating processes leads to surface qualities similar to those received from fresh electrolytes. 

After the raw chlorate has been washed, the wash water, which is rich in sodium chloride, is boiled down in an evaporator and the common salt precipitated is separated in a suction filter and reused. In this way, a portion of the sodium chloride is removed from the electrolytic liquor. Failing this the content of NaCl would continually increase, as the potassium chloride used always contains some sodium salt. Hot mother liquor is cooled in a vacuum cooler, where further portions of potassium chlorate are crystallized. 

The filtrate contains only 2-5 g of the desired product recovery is not worthwhile. The filtrate can, however, be reused as the electrolyte for conversion of further propanedioate ester. 

The precipitated mercurous chloride separates as a sludge. In the original process, some of this mercurous chloride was chlorinated to mercuric chloride for reuse. In a later version of the process, all the mercuric chloride is electrolytically converted to elemental mercury and chlorine. As of 1994, the electrolytic version had been installed in three plants. Developed by Boliden, Sweden, and Norzink, Norway, and now offered for license by Boliden Contech. 

The above reactions are at ambient temperature, so that an associated Carnot cycle (Chapter 1) is not needed, as would have been the case at high temperature. As the electrolytes are repeatedly reused, the question of the economic or thermodynamic cost of their manufacture is... 

Dudek et al. developed an electrolytic process for the one-step stripping of galvanized steel (at the anode) while recovering zinc by electroplating [22]. The zinc separated from the galvanized steel scrap was reused. As shown in Fig. 4, the galvanized... 

Electrolytic formation of finely dispersed bubbles (usually H2 and O2, from water electrolysis) can remove suspended particles from a liquid by floating them to the top. This solid matter can then be skimmed off from the top and subsequently treated. Much like electrodialysis, electroflotation is a process that concentrates the waste, which eventually needs to be treated and/or reused. It was estimated in 1980 that 20 electroflotation plants existed in the UK for treating industrial effluent [139]. Little to no information is available on the use of electroflotation for the decontamination of waste effluents in the USA. 

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