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.

Gold recovery from thiosulfate leaching

Abstract: Processes for recovering gold from copper-gold ores thiosulfate leaching or gold ores copper catalyzed thiosulfate leaching using ion exchange technology are disclosed. The processes include subjecting the gold-bearing and copper-bearing thiosulfate solution to a pH and/or temperature adjustment to reduce tetrathionate concentration in the thiosulfate solution prior to contacting with an ion exchange resin. The ion exchange resin once loaded with gold and optionally copper is eluted with a mixture of sodium tetrathionate, ammonium thiosulfate and sodium sulfite. Gold and optionally copper are recovered from the eluate by electrowinning or precipitation.

Moments analysis of restricted ternary diffusion: sodium sulfite + sodium hydroxide + water

Abstract: Ternary diffusion coefficients can be determined from restricted-diffusion experiments by evaluating zeroth and first time moments of the difference in a concentration-dependent property measured a...

A chemiluminescence reaction consisting of manganese(IV), sodium sulfite, and sulfur- and nitrogen-doped carbon quantum dots, and its application for the determination of oxytetracycline.

Abstract: Sulfur- and nitrogen-doped carbon quantum dots (S,N-CQDs) were prepared by a solid-phase hydrothermal method from cysteine and citric acid and characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and FTIR spectroscopy. These QDs were exploited as enhancers to amplify the chemiluminescence (CL) of manganese(IV)-sodium sulfite reaction. S,N-CQDs exceptionally enhanced the CL intensity of this system, around 900-fold. This effect was attributed to the energy transfer from SO2*, produced by reaction of Mn(IV) with SO32−, to S,N-CQDs. The maximum wavelength of CL emission was 480 nm, which confirmed that the final emitting species was S,N-CQDs. After optimization of reaction conditions, the analytical applicability of S,N-CQD-Mn(IV)-SO32− CL system was studied. In the presence of oxytetracycline, the CL intensity was significantly diminished. A linear relationship was observed between CL signal and the logarithm of oxytetracycline concentration in the range of 0.075–3.0 μM with a detection limit of 25 nM. This CL assay for oxytetracycline was used for analysis of spiked milk and water samples.

Effect of sodium sulfite on acid pretreatment of wheat straw with respect to its final conversion to ethanol

Abstract: A pretreatment process that combines dilute acid and sodium sulfite has been applied to wheat straw to study the effect of temperature (120–180 °C) and sodium sulfite concentration (0–3%) on the yield of glucose in subsequent enzymatic hydrolysis and ethanol production by fermentation. The results were compared with both dilute acid pretreatment (without Na2SO3 addition) and hot water pretreatment. Formation of furfural and hydroxymethylfurural, which can inhibit ethanol-producing microorganisms, were measured and the ethanol yield in a subsequent fermentation was evaluated. The results indicate that a combination of 180 °C, 30 min, 1% H2SO4 and 2.4% Na2SO3 during pretreatment produced the highest ethanol yield; 17.3 g/100 g dry weight of initial biomass, which corresponds to 75% of the theoretical yield from glucose. 28 mg of furan inhibitors (sum of furfural and hydroxymethylfurfural) per gram dry weight of initial wheat straw were generated under this condition. Increasing sulfite loading up to 2.4% decreased inhibitor formation, leading to increased delignification and preservation of cellulose from dissolution. On the other hand, an elevated temperature in combination with low pH reduced the amount of solid phase after pretreatment, increased the level of inhibitors and reduced the concentration of ethanol produced by fermentation.

Chemical removal of oxygen from natural waters

Abstract: Dissolved oxygen usually increases the corrosion rate of steel in natural waters. The effect is particularly severe in brines, because the presence of dissolved oxygen causes pitting. Therefore, various methods are employed to remove oxygen from oil-field waters, both fresh and brine, to protect the enormous investments in steel pipe and process equipment. Both mechanical and chemical methods are used to remove dissolved oxygen from water. Probably the most widely used mechanical method in the oil field is to strip the dissolved oxygen from water by countercurrent contact with a gas. This process requires a source of oxygen-free gas, usually methane. The most common chemical way of removing oxygen from oil-field waters is to add sulfur dioxide or sodium sulfite, because very little capital investment is required. A relatively simple apparatus was used to measure the rate of reaction of dissolved oxygen with hydrogen sulfide and with added chemical scavengers in oil-field waters. Results show that natural waters may catalyze or retard the reaction of sulfur dioxide or sodium sulfite with dissolved oxygen. Kinetic data for the sulfite-oxygen reaction can be obtained rapidly and accurately with a polarographic oxygen sensor.