Sodium sulfite

About: Sodium sulfite is a research topic. Over the lifetime, 2548 publications have been published within this topic receiving 18523 citations. The topic is also known as: Na2SO3 & Anhydrous sodium sulfite.

Chemimechanical pulping of birch wood chips Part 4. Effects of combined sodium hydroxide and sodium sulfite additions

Abstract: Birch wood chips were impregnated with different combinations of sodium hydroxide and sodium sulfite prior to refining, and the effects of the pretreatment on energy requirement, pulp properties and bleachability were investigated. The energy requirement was found to be decreased and the energy utilization enhanced with increased sodium hydroxide addition. Compared at constant freeness level, addition of sodium sulfite was found to increase the refining energy requirement at high addition together with low sodium hydroxide addition. This negative effect of sulfite was not recorded at higher sodium hydroxide additions. The pulp strength properties were also enhanced by increased sodium hydroxide addition, but brightness and light scattering ability were decreased. Sodium sulfite addition increased the brightness and also gave a slight improvement in strength. However, this was accompanied by a simultaneous increase in density. The bleachability of different pulps was excellent, yielding a 36-unit brightness increase at 4% hydrogen peroxide addition and an initial brightness of 33% ISO. The highest brightness obtained was 79% ISO, recorded for a pulp prepared from chips impregnated with 2.3 wt.-% sodium hydroxide and 3.5 wt.-% sodium sulfite on wood resulting in an initial brightness of 58% ISO.

Aqueous Reactions of Sulfate Radical-Anions with Nitrophenols in Atmospheric Context

Abstract: Nitrophenols, hazardous environmental pollutants, react promptly with atmospheric oxidants such as hydroxyl or nitrate radicals. This work aimed to estimate how fast nitrophenols are removed from the atmosphere by the aqueous-phase reactions with sulfate radical-anions. The reversed-rates method was applied to determine the relative rate constants for reactions of 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, and 2,4,6-trinitrophenol with sulfate radical-anions generated by the autoxidation of sodium sulfite catalyzed by iron(III) cations at ~298 K. The constants determined were: 9.08 × 108, 1.72 × 109, 6.60 × 108, 2.86 × 108, and 7.10 × 107 M−1 s−1, respectively. These values correlated linearly with the sums of Brown substituent coefficients and with the relative strength of the O–H bond of the respective nitrophenols. Rough estimation showed that the gas-phase reactions of 2-nitrophenol with hydroxyl or nitrate radicals dominated over the aqueous-phase reaction with sulfate radical-anions in deliquescent aerosol and haze water. In clouds, rains, and haze water, the aqueous-phase reaction of 2-nitrophenol with sulfate radical-anions dominated, provided the concentration of the radical-anions was not smaller than that of the hydroxyl or nitrate radicals. The results presented may be also interesting for designers of advanced oxidation processes for the removal of nitrophenol.

Recovery of iodine from waste liquid containing organoiodine compound

Abstract: PURPOSE:To produce a purified iodine product of high purity by deiodinating organoiodine compounds contained in an organoiodine compound-containing waste liquid in a high yield at a low cost and carrying out adsorption-separation-purification using an iodide ion-adsorbed ion-exchange resin. CONSTITUTION:Organoiodine compounds contained in an organoiodinecontaining waste liquid are deiodinated and converted into iodide ion or iodate ion by reduction (in the presence of metallic aluminum, metallic zinc, metallic tin or metallic silicon under an alkaline condition, in the presence of hydrosulfite, Rongalite or sodium borohydride under an alkaline condition or by heat decomposition under a strong alkaline condition) or oxidation (in the presence of chlorine gas under an acidic condition or by using a sodium hypochloride solution). After oxidation or reduction, the generated liberated iodine is then adsorbed on an iodine-preadsorbed ion-exchange resin under an acidic condition and the adsorbed iodine is subsequently eluted and separated with one or more kinds of solutions selected from a sodium bisulfite solution, a sodium sulfite solution and a sodium hydroxide solution. The obtained hydroiodic acid solution is subsequently oxidized and the resultant liberated iodine is purified according to the pressure melting method, thus producing the objective purified iodine product.

A selective spot test for nitrate ion

Abstract: The well known test for nitrate ion employing diphenylamine in sulfuric acid solution has been made selective by reducing oxidizing agents present with sodium sulfite. In nitrite-free nitrate ion solutions which are acidic, sulfite does not reduce nitrate ion. In the presence of nitrite, nitrate ion can be identified by first destroying the nitrite with sodium azide and subsequent reduction of other oxidizing agents with sodium sulfite. With this procedure 0.5/gmg of NO3− per drop can be detected readily.