Iron stripping

A sequence of tests has been devised to evaluate antioxidants for use in automotive crankcase lubricants. The Indiana Stirring Oxidation Test (ISOT) JISK2514 is an example of a laboratory screening test. The oil is stirred at 165.5°C in the presence of air. Copper and iron strips are used as metal catalysts. The development of sludge, viscosity, and acidity are deterrnined periodically. Failure time is determined when the development of acidity requires... 

NOTE Periodic cleaning of softener resin with an iron stripping formulation based on phosphonate or a terpolymer is useful. The cleaner is introduced into the resin bed, perhaps via the brine draw during resin regeneration, at a level of, say, 1 to 2 U.S. pints/cuft (16-32 ml/l) of resin. The regeneration process is temporarily halted for several hours and the resin is allowed to soak the process is then restarted and the stripped iron goes to drain. 

SWNTs and (2) iron-stripped (purified) SWNTs (0.12-0.5 mg/ml) macrophages SWNT might play an important role in determining redox-dependent responses of macrophages. et al. (2006)... 

Accdg to Greener (Ref 7, p 22), the earliest cast cannons made of copper and tin were produced by a founder named Aran at Augsburg, Germany. They were primitive breech-loaders, built up of iron strips surrounded by iron rings — a method which continued for several centuries (See illustrations on p 22 of Ref 7)... 

Fig. 12.29. When iron strips are imbedded in sand, it is the imbedded part that undergoes intensive dissolution.

Iron precipitates copper, silver, antimony, lead, and tin from solutions of their salts. In the ease of tin the deposit may be exceedingly small, as it forms a thin protecting layer on the surface of the iron. For this reason iron dissolves much less rapidly in an acid if a tin salt is present. A pretty experiment consists in immersing a strip of iron in a tube containing a solution, the bottom half of which consists of a concentrated electrolyte in which some tin salt is dissolved, and the upper half a dilute solution of the electrolyte without any tin. The lower portion of the iron strip becomes covered with crystals of tin, whilst the upper portion is quite free, although if completely immersed in the lower portion no tin deposit would be visible.4... 

When copper or iron strips were placed in water after long exposure to benzyl bromide vapors, they showed much greater dissolution than unexposed strips (Table IV) (97). Replacement of water by deuterium oxide as the reaction medium yielded CHjD as the primary gaseous products (97). While this would arise from the hydrolysis of a metal-methyl bond ... 

In short, the more active metals displace the less active metals from solution. As an example, if an iron strip is immersed in a solution of copper sulfate, some of the iron dissolves, forming iron ions, while the copper ions become metallic and copper metal plates out on the remaining iron strip. The activity series can be used to predict displacement reactions between atoms and ions in compounds of the type A + BC AC + B, where A and B are atoms. Using the activity series, any atom A will displace from a compound any element B listed below it, but will not displace any element listed above it. 

It is clear from the above-mentioned literature that efficient stripping of iron from a loaded solvent, resulting in an iron strip solution with a high iron concentration, is a major problem with most of the proposed extractants or extractant mixtures. Accordingly, to enhance the stripping efficiency "reductive stripping" has been proposed. 

An option is to integrate an electro-reduction unit into the aqueous flow of an iron strip SX-unit with recycling of the strip solution until a high build-up of iron is obtained. To find out the influence of the initial ferrous concentration in the strip solution on the electro-reductive stripping efficiency, a series of experiments was performed identically with the above-mentioned electro-reductive stripping experiments, but with various initial concentrations of ferrous sulphate. The temperature was 50°C and voltage was set to 20 V. The results are shown in Table I. 

A voltaic cell similar to that shown in Figure 20.5 is constructed. One electrode half-cell consists of a silver strip placed in a solution of AgN03, and the other has an iron strip placed in a solution of FeCl2. The overall cell reaction is... 

Steel electrode frame. The pocket plate follows a similar process. Rectangular pockets of perforated nickel-plated iron strips are filled with active material, crimped, closed, and fixed/bolted in a nickel-plated steel frame. The assembled cells are placed in polyethylene containers and filled with KOH electrolyte. Spacing of the negative and positive electrodes is maintained by the internal assembly structure. There are no separators as are common in the lead acid battery structure. 

Use the activity series in Table 15.3 to determine which of the following ions will be reduced when an iron strip is placed in an aqueous solution of that ion (15.4)... 

When the participants in a half-reaction are ah in the aqueous phase, a conductive surface is needed for electron transfer to take place. In such cases an inert electrode of graphite or platinum is often used. In this electrochemical cell, an iron strip acts as the anode and a platinum strip acts as the cathode. Iron is oxidized at the anode and Mn04 is reduced at the cathode. 

A thin strip of iron with a mass of 15.72 g is placed into a solution containing 21.12 g of copper(II) sulfate and copper begins to form. After a while, the reaction stops because all of the copper(II) sulfate has reacted. The iron strip is found to have a mass of 8.33 g. The mass of copper formed is found to be 8.41 g. What mass of iron(II) sulfate has been formed in the reaction ... 

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