Chlorides ion removal

Now the aldol reaction can occur the positive charge on the titanium-complexed carbonyl oxygen atom makes the aldehyde reactive enough to be attacked even by the not very nucleophilic silyl enol ether. Chloride ion removes the silyl group and the titanium alkoxide captures it again. This last step should not surprise you as any alkoxide (MeOLi for example) will react with Me3SiCl to form a silyl ether. 

For one mole of Fe, the volume of FeOOH (red rust) is 21.3cm-3 and the volume of Fe304 (magnetite) is 14.9 cm 3. This involves a 30% reduction in volume, which allows the electrolyte to penetrate more easily through the corrosion products and reach the deeply-buried chloride ions. In addition, the negatively-charged chloride ion migrates due to the influence of the electric field, from the cathode (artefact) toward the anode. This speeds up the rate of chloride ion removal and decreases the time for conservation. 

Environmental modifications such as deaeration, chloride ion removal, and the addition of corrosion inhibitors can reduce the risk of pitting. However, the beneficial effects on existing pits with established highly corrosive microenvironments may be minimal. Furthermore, if the pitting attack is not eliminated completely through the use of corrosion inhibitors, penetration can actually be accelerated due to the concentration of metal dissolution onto a smaller area. 

The raw precious metal concentrate is totally dissolved in hydrochloric acid—chlorine solution to form the soluble chloride ions of each of the metals. Silver remains as insoluble silver chloride and can be filtered off. Gold, in the form of [AuClJ, is extracted with, eg, tributyl phosphite or methyl isobutyl ketone. Base metals are also extracted in this step, and are removed from the organic phase by scmbbing with dilute hydrochloric acid (HCl). Iron powder is then used to reduce the gold species and recover them from the organic phase. 

Demineralizers are often used to treat raw makeup water or condensate where high purity is required, such as in large central station boHers that operate at high steam pressures. Demineralizers employ a combination of cation and anion exchange to remove additional material, including sodium and ammonium cations. VirtuaHy aH salt anions, such as bicarbonate, sulfate, and chloride, are removed and replaced by hydroxide ions in the demineralizer. 

Silver and sulfur combine even in the cold to form silver sulfide. The tendency of silver to tarnish is an example of the ease with which silver and sulfur compounds react. PoHshes that contain silver complexing agents, such as chloride ion or thiourea, are used to remove silver tarnish. 

Calcium thiosulfate has been prepared from calcium sulfite and sulfur at 30—40°C, or from boiling lime and sulfur in the presence of sulfur dioxide until a colorless solution is obtained. Alternatively, a concentrated solution of sodium thiosulfate is treated with calcium chloride the crystalline sodium chloride is removed at low temperature. Concentrated solutions of calcium thiosulfate are prepared from ammonium thiosulfate and lime the Hberated ammonium ion is recycled to the ammonium thiosulfate process (85). 

Impurities in bromine may be deterrnined quantitatively (54). Weighing the residue after evaporation of a bromine sample yields the total nonvolatile matter. After removing the bromine, chloride ion may be deterrnined by titration with mercuric nitrate, and iodide ion by titration with thiosulfate water and organic compounds may be detected by infrared spectroscopy sulfur may be deterrnined turbidimetricaHy as barium sulfate and heavy metals may be deterrnined colorimetricaHy after conversion to sulfides. 

Pulp bleaching with chlorine dioxide is most often performed at an acidic pH, so that the final pH of the bleach Hquor is in the range of 2—5. Under these conditions, the residual concentration of chlorite and chlorate ions in the bleach Hquor are minimized and chloride ion is the predominant chlorine species in the spent bleach (77). In addition to direct addition to pulp in bleaching, chlorine dioxide also finds use in wastewater treatment from pulp mill operations as a means to remove effluent color (85). 

Other ions, eg, ferrate, chloride, and formate, are determined by first removing the cyanide ion at ca pH 3.5 (methyl orange end point). Iron is titrated, using thioglycolic acid, and the optical density of the resulting pink solution is measured at 538 nm. Formate is oxidized by titration with mercuric chloride. The mercurous chloride produced is determined gravimetricaHy. Chloride ion is determined by a titration with 0.1 Ai silver nitrate. The end point is determined electrometricaHy. 

Impurities in a corrodent can be good or bad from a corrosion standpoint. An impurity in a stream may act as an inhibitor and actually retard corrosion. However, if this impurity is removed by some process change or improvement, a marked rise in corrosion rates can result. Other impurities, of course, can have very deleterious effec ts on materials. The chloride ion is a good example small amounts of chlorides in a process stream can break down the passive oxide film on stainless steels. The effects of impurities are varied and complex. One must be aware of what they are, how much is present, and where they come from before attempting to recommena a particular material of construction. 

It was found that sorbed palladium might catalyse reaction of Mn(III) reduction by Cf not only after it s removing from coal, but AC with palladium, Pd/AC, has also his own catalytic effect. On the base of dependence between characteristics of AC, chemical state of palladium on AC surface and catalytic action of Pd/AC in indicator reaction it might establish, that catalytic action concerns only to non-reduced or partly reduced palladium ions connected with chloride ions on coal surface. The presence or absence of catalytic action of Pd/AC in above-mentioned reaction may be proposed for determination of chemical state of palladium on AC surface. Catalytic effect was also used for palladium micro-amounts determination by soi ption-catalytic method. 

Potassium thiocyanate [333-20-0] M 97.2, m 172°, pK -1.85 (for HSCN), Crystd from H2O if much chloride ion is present in the salt, otherwise from EtOH or MeOH (optionally by addition of Et20). Filtered on a Buchner funnel without paper, and dried in a desiccator at room temperature before being heated for Ih at 150°, with a final 10-20min at 200° to remove the last traces of solvent [Kolthoff and Lingane J Am Chem Soc 57 126 1935]. Stored in the dark. 

FIG. 9 Example of a two-ion cluster the cluster contains sodium and chloride ions surrounded by water molecules to form a two ion cluster. The bottom cluster shows the sodium ion more clearly, after some water molecules in front of it have been removed [25]. 

Remove traces of ethanol and dissolve precipitate in a minimum (10 ml) of distilled water. Molecular sieving on a Sephadex G25 fine column (1300 ml, 0 5 cm). Assay fraction for /3-poly(L-malate) and chloride ions. Use only salt-free fractions. 

The amount of reddish-purple acid-chloranilate ion liberated is proportional to the chloride ion concentration. Methyl cellosolve (2-methoxyethanol) is added to lower the solubility of mercury(II) chloranilate and to suppress the dissociation of the mercury(II) chloride nitric acid is added (concentration 0.05M) to give the maximum absorption. Measurements are made at 530nm in the visible or 305 nm in the ultraviolet region. Bromide, iodide, iodate, thiocyanate, fluoride, and phosphate interfere, but sulphate, acetate, oxalate, and citrate have little effect at the 25 mg L 1 level. The limit of detection is 0.2 mg L 1 of chloride ion the upper limit is about 120 mg L . Most cations, but not ammonium ion, interfere and must be removed. 

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