Substitute of sodium hydrosulfite in bleaching of talc ore. (1 reply) Sodium hydrosulfite (or sodium dithionite) is an excellent reducing agent. It acts as a hematite reductant in bleaching process of talc the reaction is very fast at room temperature.
To address this limitation our laboratory previously developed a low-cost, equipment-free, point-of-care, paper-based SCA test. Here, we improved the stability and performance of the test by replacing sodium hydrosulfite (HS), a key reducing agent in the hemoglobin solubility buffer which is not stable in aqueous solutions, with sodium ...
In the textile industry, sodium dithionite is primarily used as reducing agent for vat dyes and sulfur containing dyes, and for the removal of pigments on textiles. It is also used as a bleaching agent in reductive bleaching processes, for instance, in the bleaching of mechanical paper pulp, and the bleaching of cotton and wool, as well as sugar.
HYDROSULFITE BLEACHING CONDITIONS Bleaching chemicals % wt. on pulp sodium hydrosulfite (Na 2 S 2 O 4) 0.2 1.2% Consistency (Cs.) and pH 4 10% Cs. and pH 5 7 (pH 6.0 optimum) Temperature, time and vessel 50 60 C, 0.5 2 hours and up-flow tower Consistency weight pulp / (weight of pulp weight of water)
bleached with the coomercial sodium hydro sulfite. Improvements in viscosity have been with same types of clay. The production costs are 39-64 lower than the commercial bleach. Material and Methods Laboratory Experiments Unbleached kaolin slurries (20-30 solids) were bleached in the laboratory by adding iron
BASF later developed the formate process in which sodium formate is converted with bisulfite to sodium dithionite. Sodium formate is produced from carbon monoxide and sodium hydroxide. Dithionite was used for the first time for bleaching of mechanical pulp in the 1930s. Initially, sodium dithionite was used in small amounts as a powder.
Sulphite deinking in neutral and near-neutral conditions have additionally been extensively studied in laboratory and also in mill scale. In sodium sulphite deinking, sodium sulphite replaces sodium hydroxide, hydrogen peroxide and silicate in the pulper. 3, 14, 15, 16, 17, 18 During a short mill trial it was observed that sulphite
Apr 26, 2017 Why people choose Thiourea Dioxide to replace Sodium Hydrosulfite in Textile and Paper industry ... In bleaching wool with TDO, uniform dyeing is obtained due to its slow.
Pratima Bajpai, in Environmentally Benign Approaches for Pulp Bleaching, 2005. 5.3 Bleaching with dithionite. Sodium dithionite is a reductive bleaching chemical. It is also known as sodium hydrosulphite. Reductive bleaching is especially essential not only for bleaching, but also for removing colour from coloured recovered paper and carbonless paper (Hache et al.,
Sodium hydrosulfite, also known as sodium dithionite, can be made by cathodic reduction of sodium bisulfite (ECHO Process, Fig. 5.48). Important for the success of this reaction is the use of a high surface, multilayer stainless steel fiber cathode. This allows a low CD at the cathode for efficient reduction combined with a compact cell design.
The invention relates to a method of bleaching waste paper pulp. The pulp is first treated to a reductive chemical followed by acidification and washing or dewatering. The pulp is then subjected to ozone and then to hydrogen peroxide. The reductive chemical used is either formamidine sulphinic acid or sodium hydrosulfite.
Nov 16, 2019 The bleach is formed by mixing an iron sponge powder (-325M) with slurry treated with SO2. The process has been successfully demonstrated in production, and applied to several grades. The color, brightness, and viscosity of the bleached product is equivalent to or better than that of product bleached with commercial sodium hydrosulfite.
US4357256A US06/128,098 US12809880A US4357256A US 4357256 A US4357256 A US 4357256A US 12809880 A US12809880 A US 12809880A US 4357256 A US4357256 A US 4357256A Authority US United States Prior art keywords pulp bleaching sodium hydrosulfite composition sodium Prior art date 1979-03-13 Legal status (The legal status is an assumption
Sodium silicate 10 10 Bleaching chemical dosages, kg/t In dithionite bleaching the reaction time was 30 min at a temperature of 60C and a consistency of 4%. A dosage of 8 kg/t of dithionite was used. The pH of the dithionite stage was adjusted with H 2SO4 to 7.4 before adding the 10% active sodium dithionite solutions.
sodium bisulfite, sodium or zinc hydrosulfite (no longer used in the United States), calcium or sodium hypochlorite, hydrogen or sodium peroxide, and the Sulfur Dioxide-Borol Process (a variation of the sodium hydrosulfite method). Originally, much of the mechanical pulp was not bleached, but the bleaching of groundwood has increased and im-
Mar 01, 2005 Newsprint and similar products require only moderate pulp brightness. For this use, the mechanical pulps may be bleached to 6063% ISO brightness using a reducing agent, sodium hydrosulfite, as the bleaching agent. These
Sodium dithionite (also known as sodium hydrosulfite) is a white crystalline powder with a weak sulfurous odor. Sodium dithionite and sodium hydrosulfite have the same CAS number 7775-14-6 chemical formula so are in fact the same thing (CAS is the chemists bible). The names are pure synonyms of each other.
Sodium dithionite has been used for bleaching of mechanical pulp since the 1930s (Bajpai 2014) and has been extensively studied as such. A study investigating optimal bleaching parameters for ...
Besides being an important bleaching agent in the pulp and paper industry, sulfur dioxide is also used in the manufacture of chlorine dioxide, sodium hydrosulfite, and sodium sulfite. When SO2 is dissolved in water, it yields a complex mixture given the trivial name sulfurous acid (H2SO3), which contains SO2, H3O, S2O52, and HSO3.
The whiteness obtained in wool bleaching is enhanced by the presence of a protease, with both peroxide bleaching and when sodium dithionite or bisulphite is used. This is because the enzyme makes ...
Nov 01, 2010 Removal of formic acid from industrial waste streams with sodium hypochlorite soln becomes explosive at 55 deg C. Several explosions involving methanol and sodium hypochlorite were attributed to formation of methyl hypochlorite, especially in presence of acid or other esterification catalyst. Use of sodium hypochlorite soln to destroy acidified
bleached using 10 lb (4.5 kg) of sodium hydrosulfite/ton (0.91 metric ton) of o.d. pulp at 140F (60C) for 120 min. Bleaching was performed in 2-liter Erlenmeyer flasks containing 25 g of o.d. pulp at 3.2% consistency. Just prior to adding the sodium hydrosulfite solu tion, the pulp was de-aerated by flush ing with nitrogen.
As conventional bleaching under alkaline conditions is chemically damaging to protein fibers, a three-stage protective bleaching process in neutral ethanolwater mixtures was proposed for camel hair using mordanting with ferrous salts, oxidative bleaching with hydrogen peroxide, and reductive bleaching with sodium hydrosulfite.
immediately or shortly after exposure to Sodium Dithionite f Contact can irritate and burn the skin and eyes with possible eye damage. f Inhaling Sodium Dithionite can irritate the nose, throat and lungs causing coughing, wheezing and/or shortness of breath. f Sodium Dithionite can cause nausea, vomiting, diarrhea and abdominal pain.
The other name of sodium dithionite is sodium hydrosulfite. Hydro is oxidized into sodium bisulfite, releasing hydrogen which acts as the reducing agent. Na2S2O4 4H2 O 2Na2HSO4 3H2 Conclusion In conclusion, sodium hypochlorite (NaOCl) is the strongest oxidative bleach used in textile processing and it is highly unstable compound at ...
Hach Sodium and Potassium Ionic Strength Adjustor Powder Hach Sodium Hydroxide Solution, 0.075 N Hach Sodium Reference Standard Solution Hydrochloric Acid Hydrogen Peroxide Immersion Oil Lab Algicide LaMotte Aluminum Test Solution LaMotte Ammonia Nitrogen Test Solution LaMotte Buffer Reagent
OSTI.GOV Patent Method of preparing reproducibly stable aqueous suspensions of sodium dithionite for woodpulp bleaching
underutilized source of waste papers. Usually, several chemical bleaching agents such as ozone, oxygen, hydrogen peroxide, or sodium hydrosulfite have been used to bleach secondary fibers. Now, there is an alternative color stripping process for secondary fibers the laccase-mediator system. In a study by Arjona et al. (2007), a bleaching ...
Following the mill-scale grinding trials, lab-scale bleaching trials with sodium dithionite were performed in the laboratory of STORA ENSO Reisholz Mill (table III). After adding the bleaching agents and the bleaching addi-tives, the pulp with a consistency of 4 % was stored for a 2 h period at a temperature of 70 C in the water bath.
Consumption of sodium hydrosulfite contaminated food is health hazard. At present, sodium hydrosulfite is not permitted for use in foods by Thai FDA, but other sulfites (bleaching agents) such as sulfur dioxide, sodium sulfite, sodium bisulfite and sodium metabisulfite are allowed in accordance with the Public Health Notification No 84 (B.E.2527) regarding food additives.
Nov 30, 2019 Sodium hydrosulphite (Na 2 S 2 O 4) or sodium dithionite (PubChem CID 24489) is also known as hydros in the food, polymer, dye, and textile industries. Sodium hydrosulphite (Hydros) is one of the additives in jaggery that enhances its colour (Kumar and Kumar, 2018, Rao et al., 2007).
Bleaching agents such as sodium hypochlorite (NaOC) oxidize stains to lighten or remove them. Many dyes are also easily oxidized by NaOCI, destroying the chromophores. Reducing agents can also bleach some dyes. Sodium hydrosulfite (Na2S,0) reduces azo groups to two amino groups thus disrupting the chromophore.
Sodium metabisulfite appears as a white crystalline or powder solid with a slight sulfur odor. Toxic by inhalation . Strongly irritates skin and tissue. Noncombustible, but may decompose to emit toxic oxide fumes of sulfur and sodium when heated to high temperature. A corrosive acid when mixed with water.Used as a food preservative and as a laboratory reagent.
Use a lab apron, chemical resistant gloves and goggles before following the below method to dispose of hazardous waste. 1. Add the substance to be disposed of to a large beaker and dissolve it in water. Place the beaker in a fume hood. 2. Add an equal amount of sodium carbonate to the mixture. 3. Slowly add a 25% molar excess of bleach to the ...
Usually, sodium hydrosulfite is known as sodium dithionite. Under typical conditions, it is stable and breaks down after coming into contact with acid/compound or hot water. Sodium hydrosulfite is often used for bleaching purposes in the paper and pulp industry, textile processing, mineral ore flotation, and food additives.