Bisulfite concentration effect

Concentration. The iodine clock reaction is a convenient reaction for observing concentration effects. The reaction is between potassium iodate, KI03, and sodium bisulfite, NaHS03 the net ionic reaction is given by the following equation. 

Procedure. The procedure is outlined in Figure 1. The first step is the separation of the desired nuclides by coprecipitation with calcium fluoride. The optimum nitric acid concentration for effective carrying on calcium fluoride is between O.IN and 0.2N. Reduction of the plutonium to Pu(III) was necessary to obtain quantitative carrying on calcium fluoride. Plutonium (IV) is known to form colloidal or non-ionic species in neutral solution, and in this form may be incompletely carried by calcium fluoride. Bisulfite was effective and gave complete reduction in 3.5 hr at 50° C or overnight at room temperature. The concentration of calcium must be at least 0.1 mg/ml for quantitative carrying. 

Sulfur Dioxide and Sulfites. Sulfur dioxide [7446-09-5], SO2, sodium bisulfite [15181-46-1], NaHSO, and sodium metabisulfite [23134-05-6] ate effective against molds, bacteria, and certain strains of yeast. The wine industry represents the largest user of sulfites, because the compounds do not affect the yeast needed for fermentation. Other appHcations include dehydrated fmits and vegetables, fmit juices, symps and concentrates, and fresh shrimp (79). Sulfites ate destmctive to thiamin, and cannot be used in foods, such as certain baked goods, that ate important sources of this vitamin. 

Stablizers. Stabilizers are ingredients added to a formula to decrease the rate of decomposition of the active ingredients. Antioxidants are the principal stabilizers added to some ophthalmic solutions, primarily those containing epinephrine and other oxidizable drugs. Sodium bisulfite or metabisulfite are used in concentration up to 0.3% in epinephrine hydrochloride and bitartrate solutions. Epinephrine borate solutions have a pH range of 5.5 7.5 and offer a more difficult challenge to formulators who seek to prevent oxidation. Several patented antioxidant systems have been developed specifically for this compound. These consist of ascorbic acid and acetylcysteine, and sodium bisulfite and 8-hydroxyquinoline. Isoascorbic acid is also an effective antioxidant for this drug. Sodium thiosulfate is used with sodium sulfacetamide solutions. 

A flowsheet for the Wellman-Lord process is shown in Figure 25.26. Again the gas stream with S02 enters a scrubber into which is sprayed a sodium sulfite solution. This then goes to an evaporator/crystallizer to crystallize out the resulting sodium bisulfite, which converts the sodium bisulfite back to sodium sulfate, releasing the S02. The crystals are dissolved in water and recycled to the scrubber. The effect of the Wellman-Lord process is to produce a concentrated S02 stream from a dilute S02 stream. The resulting concentrated S02 still needs to be treated. 

The enhancement effect of magnesia on S02 removal is caused by increased concentrations of basic sulfite species, SO3 and MgS0 , that react with the strong acid S02(aq) to form bisulfite ion, HSO3. 

In a perfectly-buffered solution the SO2 vapor pressure will be directly proportional to the total concentration of SO2 and bisulfite, giving a linear equilibrium relationship. In simple alkali sulfite solution without added buffer, the equilibrium relationship is highly nonlinear, because H-1" accumulates as SO2 is absorbed. Under these conditions is it not possible to carry out reversible SO2 absorption/stripping in a simple system, resulting in greater steam requirements than expected with a linear equilibrium relationship. Weak acid buffers such as sodium citrate have been proposed to "straighten" the equilibrium relationship and thereby reduce ultimate steam requirements (Jl, 2, 7). Citrate buffer is attractive because it is effective over a wide range, from pH 2.5 to pH 5.5 in concentrated solutions. 

Series 8 in combination with earlier series was intended to provide data on the effects of total anion concentration. The results are internally consistant with the correlation, having a standard deviation of about 15% around the mean error. However the measured values of PSO2 were about 40% lower than the general correlation. An SO2 analyzer, rather than iodine titration, was used to determine SO2 gas concentration from the saturator. The analyzer was calibrated with dry SO2/N2 span gas. In later experiments it was shown that humid gas gives a lower analyzer response. With constant fraction neutralization increased anionic concentration increases PSO2 because pH decreases faster than effective bisulfite activity. 

The dependence on fraction neutralization and total anion concentration should reflect the extent to which the bisulfite activity is not proportional to total dissolved SO2. As expected, the dependence on f is quite small, since dissolved SO2 is present primarily as bisulfite at pH 3.5 to 5.0. The effect of anion concentration is in the direction expected since bisulfite activity would be reduced by ion pairing in more concentrated solutions. 

Sodium bisulfite is often preferred in pyro developers and in Phenidone concentrates (Appendix 3 Pharmacopoeia Phenidone). Sodium bisulfite3 is often used in formulas that are divided into two solutions, as its weak acidity helps to inhibit the oxidation of the concentrated developing agent. When carbonate, contained in the B solution, is added to make a working solution, the bisulfite is immediately broken down into sulfite and bicarbonate, producing a useful buffering effect. 

Recent studies have demonstrated reactions of bisulfite with pyrimidines. Addition compounds are formed at the 5,6-double bond of the pyrimidine (5). Mutagenic effects have been observed with phage A (10) and with Escherichia coli (11). However, the concentrations of bisulfite used in these experiments were 1M or higher, and one wonders if such effects would be observed at the much lower concentrations that could arise by exposure of vegetation to SOo-polluted air. 

The oxidation of S(IV) is a first order reaction with respect to S(IV) (2,3). This reaction is accelerated by the presence of metallic ions such as ferric and manganous ions which act as catalysts (4-8). Therefore, the effect of the metallic ions on the oxidation of S(IV) was investigated by using test solutions. Table I shows experimental conditions for the oxidation of S(IV) in test solutions. The pH values of synthetic rain water samples were adjusted between 3 and 6. S(IV) concentration in the test solutions was adjusted to 12.5 yM most of S(IV) existed as bisulfite at pH 3-6 (9). The rate of S(IV) oxidation was measured using ion chromatographic analysis. The pH of each test solution was adjusted by using a buffer. 

Preparation of Fremy s salt a freshly prepared sodium bisulfite solution (100 ml) is added to a mixture of sodium nitrite (345 g) and ice (200 g) in a 1-1 beaker. On addition of 20 ml of glacial acetic acid, the reaction mixture turns black. Concentrated ammonium hydroxide (25 ml) is added and the mixture is cooled in an ice bath. A 0.2 M solution (400ml) of potassium permanganate is added dropwise over 1 h and the black precipitate which forms is immediately removed by filtration. A saturated solution of potassium chloride (250 ml) is added slowly over a 45-min period while the filtrate is gently stirred in an ice water bath. The precipitate that forms is collected by filtration and washed successively with a saturated solution of potassium chloride and methanol, each containing 5% of concentrated ammonium hydroxide and, finally, with acetone. Fremy s salt should be stored in a desiccator over calcium oxide. A small amount of ammonium carbonate in a desiccator is also very effective in protecting Fremy s salt against deeomposition. 

CUSO4.5H2O, and 1.2 g of sodium chloride in 15 ml of water. Heat to effect solution, Add slowly a solution of 2 g of sodium bisulfite and 1 g of sodium hydroxide in 6 ml of water. Cool in tap water to about 20 and allow to stand for five minutes. Wash with water by decantation. Pour off most of the water, and add 3 ml of concentrated hydrochloric acid and 2 ml of water. Transfer to an Erlen-meyer flask, and add all at once the diazonium salt solution. Allow the mixture to stand for five minutes, and then heat gradually to 50-60 . Cool the solution, and remove the dark layer of chlorobenzene which separates out by means of a separatory tube. Extract the aqueous layer with 8 ml of ether, and unite the ether extract with the crude oily layer. Wash the mixture with 5 ml of water and 1 ml of sodium hydroxide solution and again with water. Dry with 0.5 g of calcium chloride, and distill. Collect the fraction which boils at 130-135 . The yield is about 2 g. 

It is found that the use of sodium bisulfite materially increases the yield of salicylic aldehyde. Further, that the lower temperatures (15° to 18°) favor the yield of salicylic aldehyde. At higher temperatures less salicylic aldehyde is produced and more of the resinous product. Up to a current density of 8 amp./sq. dm. the yield of salicylic aldehyde is increased. Intermittent electrolysis or stirring after electrolysis is necessary for good current efficiency since a sodium amalgam is built up during the electrolysis. Increasing the time of electrolysis seems to increase the quantity of resin formed. Increasing the concentration of salicylic acid (sodium salt) has little or no effect. 

With this experience in hand, the amine hydrochloride IQ was transformed into the aminonitrile 2A as shown in Figure 4. This entire sequence was carried out on an approximate 0.5 mole scale via five separate reactions without isolation of intermediates to give a 67% overall yield of aminonitrile 1A based on amine IQ. Thus, the amine hydrochloride IQ was neutralized with concentrated potassium hydroxide, and the liberated free amine Q was taken up in ether. Treatment of this solution with N-chlorosuccinimide (NCS) gave a solution of the N-chloroamine 11. Further addition of ethanolic potassium hydroxide effected dehydrochlorination. The resultant bicyclic imine 12. in ethanolic ether was sequentially treated with aqueous sodium bisulfite and then solid sodium cyanide. The desired aminonitrile 1A was isolated as a distillable liquid. 

Sulfate formation by pathways (c)was studied by Penkett (1972) and Penkett and Garland (1974). Their laboratory experiment with bulk water and water drops demonstrated that 03 oxidizes bisulfite ions very rapidly and effectively. These authors found that at 10 C, with an ozone concentration of 0.05 ppm, the sulfate formation rate is given by the following equation ... 

Golan-Goldhirsh and colleagues (71,72) report that sodium bisulfite, reduced glutathione, and ascorbic acid caused a 50% inactivation of mushroom polyphenol oxidase after 28, 106, and 130 min, respectively, at 5 mM concentration. Dithiothreitol was a more effective inhibitor, causing 50% inactivation at 0.1 mM after only 70 min. 

When increasing the pH-value of the absorption liquor, the concentration limit of Fe can be extended to at least twice the value of the limit, observed at pH = 5. The effect is based on a physico-chemical shift of the ratio of bisulfite to sulfite with increasing pH-value, resulting in an increased rate of oxidation of sulfite. As a consequence, oxidation of the oxygen-carrier Fe is retarded. 

Concerning the catalytic effect of the metal ions mentioned above, research has been focused on Co, Mn " or Cu [1>5]- Little and contradictory data is available about the effect of Fe " [2,3,6,7,9]. Target of the present project has been, to examine the role of Fe and the role of Fe " combined with Mn, as well as the influence of the pH-value in sulfite/bisulfite oxidation. Provided a better understanding of this subject, the performance of S(IV) oxidation in FGD could be optimised by choosing absorption additives with appropriate catalyst concentration or by adding catalyst, to achieve the optimum concentration for maximum oxidation yield, as already suggested by Gmelin [3]. 

As in the case of temperature, concentrations have a marked effect on dissociation rates but the effect on the actual equilibrium constants of sugar-bisulfite addition compounds is very small. Table VIII is an adaptation from Sundman (1949, p. 25) illustrating this feature. Con-... 

Effect of Temperature on Sugar-Bisulfite Equilibrium Constants Temperature, Sugar concentration, pH ... 

The formation of the a-hydroxysulfonic acids is influenced by concentration of the reactants (carbonyl compound and bisulfite), temperature, and pH. The rate of association as influenced by the relative concentration of bisulfite, aldehyde, and sugars was investigated early by Kerp (1904) and his collaborators and others, and more recently by Ingram and Vas (1950b) and by the Corn Products Refining Company. The effect of pH and temperature on dissociation of the sulfonic acids has been investigated also for some of the compounds (see the review by Suter,... 

The Chemical Division of the Corn Products Refining Company investigated the effect of temperature, concentration, alcohol, and free sulfurous acid on the degree of association of glucose and sodium bisulfite in aqueous solution in connection with the research sponsored by the Subsistence Section of the QMC Research and Development Branch during World War II on browning. 

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