Showing papers on "Sodium sulfite published in 2019"

Photocatalytic Hydrogen Production: Role of Sacrificial Reagents on the Activity of Oxide, Carbon, and Sulfide Catalysts

Abstract: Photocatalytic water splitting is a sustainable technology for the production of clean fuel in terms of hydrogen (H2). In the present study, hydrogen (H2) production efficiency of three promising photocatalysts (titania (TiO2-P25), graphitic carbon nitride (g-C3N4), and cadmium sulfide (CdS)) was evaluated in detail using various sacrificial agents. The effect of most commonly used sacrificial agents in the recent years, such as methanol, ethanol, isopropanol, ethylene glycol, glycerol, lactic acid, glucose, sodium sulfide, sodium sulfite, sodium sulfide/sodium sulfite mixture, and triethanolamine, were evaluated on TiO2-P25, g-C3N4, and CdS. H2 production experiments were carried out under simulated solar light irradiation in an immersion type photo-reactor. All the experiments were performed without any noble metal co-catalyst. Moreover, photolysis experiments were executed to study the H2 generation in the absence of a catalyst. The results were discussed specifically in terms of chemical reactions, pH of the reaction medium, hydroxyl groups, alpha hydrogen, and carbon chain length of sacrificial agents. The results revealed that glucose and glycerol are the most suitable sacrificial agents for an oxide photocatalyst. Triethanolamine is the ideal sacrificial agent for carbon and sulfide photocatalyst. A remarkable amount of H2 was produced from the photolysis of sodium sulfide and sodium sulfide/sodium sulfite mixture without any photocatalyst. The findings of this study would be highly beneficial for the selection of sacrificial agents for a particular photocatalyst.

Selective Reduction of Nitrate into Nitrogen Using Cu/Fe Bimetal Combined with Sodium Sulfite

Abstract: A novel two-step reduction process was constructed to removal nitrate selectively in aqueous solution. Nitrate was preliminarily reduced into nitrite with low yield of ammonia by microscale Cu/Fe b...

Sulfonation of Hydroxymethylated Lignin and Its Application

Abstract: To valorize kraft lignin, hydroxymethylation and sulfonation were applied on this under-utilized, but vastly available, material. The hydroxymethylation pretreatment was conducted as means to improve the reactivity of lignin. The sulfonation of hydroxymethylated kraft lignin was investigated by sulfuric acid and sodium sulfite treatments under various conditions. The modified lignin samples were characterized for their charge density, solubility, elemental components, and molecular weights. The results showed that the hydroxymethylation facilitated the sulfonation by sodium sulfite, yielding a product (SSH-lignin) with the charge density of -1.2 meq/g and water solubility of 10 g/L under the conditions of H 2 SO 3 /lignin molar ratio of 0.49 mol/mol, 95℃ and 3 h. On the other hand, hydroxymethylation hindered the sulfonation of lignin by sulfuric acid, yielding a product (SAH-lignin) with the charge density of -0.46 meq/g and solubility of 0.9 g/L under the conditions of H 2 SO 4 /lignin molar ratio of 14.8 mol/mol, 80℃ and 1 h. The SSH-lignin had a high adsorption on kaolinite (17 mg/g) at a lignin concentration of 40 g/L. The sulfonated lignins were also found to be effective coagulant for the cationic dye ethyl violet.

Improving enzymatic hydrolysis efficiency of corncob residue through sodium sulfite pretreatment

Abstract: The effects of sodium sulfite pretreatment on the delignification rate, cellulose content, enzymatic hydrolysis efficiency, and glucose yield of corncob residues (CCR) were investigated. The optimum pretreatment conditions were as follows: 12% sodium sulfite, with a pH value of 7, a temperature of 160 °C, and a holding time of 20 min. Under the optimal conditions, the cellulose content in the pretreated residue was 85.17%, and sodium lignosulfonate with a sulfonation degree of 0.677 mmol/g was obtained in the waste liquids. A delignification rate of 77.45% was also achieved after the pretreatment. Enzymatic hydrolysis of pretreated CCR was carried out with cellulase (5 FPU/g substrate) and β-glucosidase (10 IU/g substrate) for 48 h. The untreated CCR were hydrolyzed using cellulase (20 FPU/g substrate) and β-glucosidase (10 IU/g substrate) for 48 h. The comparison results showed that sodium sulfite pretreatment improved the enzymatic hydrolysis efficiency and glucose yield, which increased by 28.80% and 20.10%, respectively. These results indicated that despite the application of low cellulase dosage, high enzymatic hydrolysis efficiency substrate could be produced, and the sodium lignosulfonate which can be used for oilfields and concrete additives was obtained from the sodium sulfite-pretreated CCR.

Potentiometric Determination of Chlorate Impurities in Hypochlorite Solutions.

Abstract: The method of iodometric determination of chlorates impurities in sodium hypochlorite solutions for medical and veterinary purposes was developed. This method does not require sophisticated equipment and can be implemented directly where the solutions are used. The method is based on the different rates of interaction of ClO- and with iodide ions depending on the acidity of the medium. We have shown that blank titration is advisable to improve the accuracy of the determination of low concentrations of chlorates in the matrix of hypochlorite which is present in excess since in this case possible systematic errors due to the presence of oxidizing impurities in the reagents are prevented. To quantify the low concentrations of chlorates, we proposed to remove 85-95% of hypochlorite ions by means of reducing their excess with sodium sulfite at pH 10.5. The solution of sodium sulfite does not require standardization before each analysis in the proposed procedure. The possibility of quantitative determination of chlorate impurities in the range of 2-50 mg/L in the presence of 50-500–fold excess of sodium hypochlorite with an error of 5% has been proved. The expanded uncertainty of chlorate determination did not exceed 0.6 mg/L.

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.

Effect of sodium sulfite, tartaric acid, tannin, and glucose on rheological properties, release of aroma compounds, and color characteristics of red wine

Abstract: In this study, we evaluated the effect of addition of non-volatile compounds (sodium sulfite, tartaric acid, tannin, and glucose) on the rheological properties, release of aroma compounds, and color of the red wine. While determining the rheological properties of the supplemented samples, non-Newtonian fluidic and shear-thinning behavior of samples was noticed. The viscosity of these samples was found in negative correlation with the dose of addition of various non-volatile substances. The aroma profile of red wine after additions showed the change in the release of the nine key aroma compounds. Among them ethyl hexanoate, phenylethyl alcohol, octanoic acid, diethyl succinate, and ethyl octanoate were profoundly increased. Further, the color of red wines was improved in the presence of tartaric acid and tannin. Overall, supplementation of various substances during storage period of three different wines could enormously affect the sensory characteristics in a dose dependent manner.

Sodium Selenosulfate from Sodium Sulfite and Selenium Powder: An Odorless Selenylating Reagent for Alkyl Halides to Produce Dialkyl Diselenide Catalysts

Abstract: Na2SeSO3, which can be generated in situ by the reaction of Na2SO3 with Se power, was found to be an odorless reagent for the selenenylation of alkyl halides to produce dialkyl diselenides. These products have been recently shown to be good catalysts for the Baeyer–Villiger oxidation of carbonyl compounds, for the selective oxidation of alkenes, or for the oxidative deoximation of oximes. By using aqueous EtOH as the solvent and avoiding the generation of a malodourous selenol intermediate, the selenylation reaction with Na2SeSO3 is much more environmentally friendly than conventional methods. Owing to the cheap and abundant starting materials and selenium reagents, our novel synthetic method reduces the production costs of dialkyl diselenides as organoselenium catalysts, thereby advancing practical applications of organoselenium-catalysis technologies.

Quantification of Tannins from Curupay Bark

Abstract: This study aimed to assess the influence of time and sodium sulfite concentration on tannin yield in Curupay bark and propose better extraction conditions. The extractions were performed using 100 g of dried bark and 1500 mL of water at 70 °C, with extraction times of 2, 3, and 4 h and amount of extractor salt at the concentrations of 0, 1, 2, 3, and 4%. The following parameters were evaluated: content of total solids, total yield of solids, Stiasny index, and gravimetric yield of condensed tannins and non-tannins. Results show that the higher the concentration of sodium sulfite, the higher the content and yield of solids, as well as the higher the extraction of non-tannin compounds. Three-hour extraction time at 3.0% sodium sulfite concentration was the best condition to extract tannins from Curupay bark, under which a condensed tannin yield of 20.46% was obtained.

Purification of 2,4,6-trinitrotoluene by digestion with sodium sulfite and determination of its impurities by gas chromatography–electron capture detector (GC-ECD)

Abstract: Unwanted compounds in 2,4,6-trinitrotoluene (TNT) explosive, such as dinitrotoluene (DNT) and TNT isomers, can lead to exudation defects in the ammunition. For this reason, separation and analysis of impurities are valuable. Chemical treatment with sulfite solution is an important method for the purification of TNT. In this paper, TNT was purified by sodium sulfite solution with putting flaked TNT in digestion condition to remove existing impurities, and the effect of four main factors, digestion temperature, digestion time, concentration of sulfite solution and reaction time of sulfite with impurities on this purification process, was statistically investigated and optimized using central composite design of experiment (CCD) by Minitab software. Also, the qualification of final product was characterized by gas chromatography–electron capture detector method. Here, some conventional compounds such as 2,6-DNT, 2,4-DNT, 3,4-DNT, 2,4,5-TNT (γ-TNT), 2,3,4-TNT (β-TNT) and aniline derivatives were identified by standard solutions; then their concentrations were quantitatively determined by internal standard calibration method.

Effect of Antioxidants on Stability of Aqueous Solutions of Selenurea and on Properties of Lead Selenide Films Obtained with These Antioxidants

Abstract: Spectrophotometric method was used to study the kinetics of the process in which aqueous solutions of selenurea of various compositions are oxidized. Significant differences between the stabilities of selenurea solutions were revealed in relation to the selenurea concentration and also to the acidity, or alkalinity of a medium. It was shown that the stability of selenurea solutions is affected by additives of various antioxidants: sodium sulfite Na2SO3, ascorbic acid C6H8O6, hydroxylamine chloride NH2OH·HCl, hydrazine hydrate N2H4·H2O, and tin chloride SnCl2·2H2O. It was found that using a 1 : 1 mixture of antioxidants Na2SO3 and C6H8O6 substantially raises their antioxidant activity and stabilizes the aqueous solutions of selenurea during up to five days. A hydro-chemical precipitation in the acetate—ethylenediamine reaction system in the presence of the antioxidants under study was used to obtain lead selenide films of stoichiometric composition with thicknesses of 230‒670 nm. With the Na2SO3 + C6H8O6, Na2SO3, C6H8O6, and SnCl2 antioxidants used to stabilize selenurea solutions, a tendency is observed toward a decrease in the lattice constants of PbSe films from 6.1531 ± 0.0003 to 6.1367 ± 0.0002 A, an increase in the share of nanosize particles, and rise in the PbSe energy gap width from 0.78 to 1.0 e V.

Method of separating and recovering valuable metals from waste lithium battery materials and application thereof

Abstract: The invention discloses a method of separating and recovering valuable metals from waste lithium battery materials. The method comprises the following steps that a positive electrode material of a battery is leached by using sulfuric acid and a reducing agent, and filtering is carried out after the reaction is completed to obtain a leachate, wherein the reducing agent is one kind or multiple kindsof glucose, cane sugar, vitamin C, grape seeds, sodium thiosulfate and sodium sulfite; an additive is added into a leaching solution so as to adjust the pH value of the leaching solution in the rangeof 10-12, nickel, cobalt and manganese ions in the leaching liquid are enabled to be co-precipitated, and filtering is carried out to obtain a nickel-cobalt-manganese-containing precipitate and a lithium-ion solution after the reaction is finished; and the lithium-ion solution is concentrated to 20-45 g/L, excessive anhydrous sodium carbonate is added into the concentrated lithium-ion solution for reaction to obtain precipitate lithium carbonate; and the invention further discloses application of the product prepared by the method in battery production. According to the method and the application, leaching efficiency is high the process is simple, the waste liquid can be treated to prepare the terminal product lithium carbonate, and the pollution caused by the waste lithium battery to theenvironment can be effectively reduced.

Dissolution Behavior of Gold in Alkaline Media Using Thiourea

Abstract: In this work the dissolutive behavior of gold in alkaline medium using thiourea (TU), under different variables, was studied in a theoretical and experimental way, in order to determine the conditions under which it is feasible to dissolve gold in thiourea-alkaline medium. A thermodynamic study was conducted by chemical speciation using the method of Ro-jas-Hernandez, together with an electrochemical study where the electric potential was swept in the anodic direction. The main results of the thermodynamic study were that formamidine disulfide (FDS) and sulfinic compounds (S.C.) prevail at alkaline pH; by increasing the initial concen-tration of thiourea at alkaline pH, the presence of the gold complex is al-most zero for any initial concentration of thiourea. By including sodium sulfite in the gold-thiourea system, it was possible to obtain the Au(I)-TU complex at alkaline pH, with a presence of 95.13%. Electrochemical tests allowed verifying that in the absence of sodium sulfite the dissolution of gold in an alkaline medium is very slow but adding sodium sulfite im-provements become evident in the dissolution of the metal. Therefore, sodium sulfite catalyzes the gold dissolution process and stabilizes the thiourea. With this study it was possible to establish the feasibility of using thiourea in an alkaline medium for the dissolution of gold, and the conditions under which it is possible to dissolve the gold in that medium. With these fundamentals and conditions, it is now possible to move forward to test this system for minerals and/or concentrates containing gold.

Method for recycling sodium sulfite by desulfurizing fluid catalytic cracking flue gas

Abstract: The invention discloses a method for recycling sodium sulfite by desulfurizing fluid catalytic cracking flue gas, and relates to the technical field of catalytic cracking processes. The method comprises the following steps of: enabling tower bottom slurry as circulating slurry to return to a washing tower to be in contact with fluid catalytic cracking flue gas, controlling the concentration of thecirculating slurry to be 10%-15% by adopting a way of adjusting the amount of supplementing water; and performing evaporative crystallization and centrifugal separation on filtrate obtained by filtering of a part of the tower bottom slurry. The sodium sulfite product with the purity of higher than 90% is obtained by adopting the method, the additional value of the product is high, and the productcan be used as a raw material for producing a concrete conditioner.

Sequential chemical reduction and alkalinization for in-situ generation of magnetites from Fe3+-rich wastewater

Abstract: Chemical reduction of Fe3+ by sodium sulfite (Na2SO3) followed by NaOH alkalinization was used to remove and recover the metal as magnetite from model Fe3+-rich Fenton-treated solution. The compact and low-volume flocs exhibited magnetic character and the X-ray diffraction pattern showed close similarity to a standard magnetite. Anions such as oxalate and sulfate were found to lower the Fe3+ reduction efficiency so that an appropriate adjustment on the amount of Na2SO3 is necessary in their presence.

Method for preparing iron-sulfide-supported alpha-crystal-form iron oxyhydroxide catalyst

Abstract: The invention discloses a method for preparing an iron-sulfide-supported alpha-crystal-form iron oxyhydroxide catalyst. The method is characterized in that the catalyst is synthesized by means of a one-step hydrothermal method, an anhydrous sodium sulfite ion aqueous solution is slowly added dropwise into ferrous sulfate heptahydrate solution ionized water, high-speed stirring is carried out, thenthe whole mixed solution is put into a high-pressure reaction kettle, the high and constant temperature is kept for heating, after cooling is conducted to room temperature, high-speed centrifugal separation is conducted to obtain the iron-sulfide-supported alpha-crystal-form iron oxyhydroxide catalyst material, and synthesized FeS2 and alpha-FeOOH are both nano-scale materials, wherein the mole ratio of ferrous sulfate heptahydrate to anhydrous sodium sulfite is 1:(8+/-0.1), the reaction temperature of the ferrous sulfate heptahydrate and the anhydrous sodium sulfite in the high-pressure reaction kettle is 160-200 DEG C, and the reaction time is 1-2 hours. By means of the method, iron oxyhydroxide and iron sulfide are supported together, the efficiency is improved on the premise of savingresources, and the purpose of directionally removing heavy metal ions and macromolecular organic pollutants in water is achieved.

Method for preparing archaized wood material

Abstract: The invention discloses a method for preparing an archaized wood material. The method comprises the steps that firstly, the wood material is put into a mixed solution containing sodium hydroxide and sodium sulfite to be pretreated; secondly, the pretreated wood material is rinsed so as to remove residual sodium hydroxide and sodium sulfite; and thirdly, the rinsed wood material is put into a solution containing metal salt to for the reaction, and the archaized wood material is obtained. According to the method for preparing the archaized wood material, the obtained archaized wood material achieves full color changing from inside to outside, and the later-period sanding, planing and the like are not affected.

Method of using sulfite enhanced divalent copper to catalyze persulfate oxidation to degrade organic pollutants

Abstract: The invention discloses a method of using sulfite enhanced divalent copper to catalyze persulfate oxidation to degrade organic pollutants. Due to the reducing performance of sulfite, the conversion ofdivalent copper ions into monovalent copper ions is promoted; the yield of sulfate radicals is increased, and the degradation efficiency of organic pollutants is improved. The water treatment comprises following steps: adjusting the pH value to 6-11; adding a certain amount of divalent copper ions into a water sample to be processed, then adding a certain amount of a potassium sulfate solution and a sodium sulfite solution, fully stirring and mixing, and carrying out reactions for 5 to 30 minutes to effectively degrade the organic pollutants. The problems of a conventional divalent copper catalyzed persulfate system such as long start period, low yield of sulfate radicals, a large amount of added divalent copper ions, a large amount of generated sludge, and the like are solved. At the same time, the method has the advantages of high active group yield, good organic pollutant removing efficiency, convenient operation, and low operation cost.

Formulations of anhydrous sodium thiosulfate

Abstract: Described herein is anhydrous sodium thiosulfate, methods for synthesizing anhydrous sodium thiosulfate, pharmaceutical compositions thereof, and methods of treating ototoxicity. Anhydrous sodium thiosulfate is synthesized from sodium sulfite, sulfur, and cetylpyridinium chloride. The anhydrous sodium thiosulfate is formulated into a pharmaceutical composition comprising a buffer and solvent. These compositions are useful for eliminating or reducing ototoxicity in pediatric patients receiving platinum based chemotherapeutics.

A new sulfur-doped source and synergistic effect with nitrogen for carbon dots produced from glucose*

Abstract: The nitrogen and sulfur-co-doped carbon dots (N, S-CDs) with increased luminescence were synthesized by hydrothermal process in one green pot by glucose, and a new sulfur-doped source of sodium sulfite was developed. The synergistic effect mechanism of the N and S groups were well discussed through the structure analysis of Fourier transform infrared spectra and X-ray photoelectron spectra. The surface states of N, S-CDs embody more complicated functional groups, and S element exists as -SSO3, -C-SO3 and SO4 2- group due to the introduction of sodium sulfite. The sulfur-containing groups passivate the surface of CDs, and the relatively high sulfur groups may reduce the non-radiation centers. The fluorescence is affected by hydroxyl group of the solvent. The quenching of Fe3+ ion to fluorescence and the sensitivity of pH to fluorescence was also investigated.

Method for preparing lead selenide thin film by chemical liquid phase method

Abstract: The invention relates to a method for preparing a lead selenide thin film by a chemical liquid phase method, and belongs to the field of preparation of semiconductor materials. According to the method, lead acetate and selenium powder are respectively adopted as a lead source and a selenium source, and sodium selenosulfate is prepared by taking the selenium powder and the sodium sulfite as raw materials; sodium citrate is used as a complexing agent; the pH value is adjusted through potassium hydroxide; the obtained deposition liquid is placed into a water bath kettle, and heating is carried out for 3-4 hours at a temperature of 75 DEG C; and drying is carried out to obtain the lead selenide thin film. The raw materials used in the synthetic method are easy to obtain, the process is simpleand convenient, the method has the advantages of low cost, high yield and capability of large-scale production, and therefore, the method has a very wide application prospect.

Preparation method of dandelion/sugar biochar composite structure

Abstract: A preparation method of a dandelion/sugar biochar composite structure includes the following steps: adding dandelion to water, adding mixed sugar, and carrying out ultrasonic stirring to obtain a solution B; freeze-drying the solution B to obtain a product C; adding concentrated sulfuric acid and water to the product C, and putting the product C in a hydrothermal reactor for reaction to obtain a solution D; diluting the solution D to neutral, and drying the solution D to obtain a product E; evenly laying a layer of conductive graphite on the product E, and putting the product E in a tubular furnace for reaction to obtain a product F; repeatedly washing the product F with ethanol and water, filtering the product F in a pumping manner, and drying the product F to obtain a product G; mixing the product G with sodium sulfite, and adding concentrated hydrochloric acid and water to obtain a mixture H; and diluting the mixture H to neutral, and putting the mixture H in a tubular furnace for reaction to obtain a final product. The preparation technology is simple, and the raw materials are easily available. The prepared dandelion/sugar biochar composite structure can inhibit the decomposition of polysulfides in electrolyte and improve the capacity of lithium sulfur batteries when used in lithium sulfur batteries.

Separation and purification process of taurine

Abstract: The invention relates to a separation and purification process of taurine and is applicable to methods for synthesizing taurine from ethylene oxide as a raw material. The process specifically comprises the following steps: mixing ethylene oxide with sodium hydrogen sulfite and other gas, liquid and solid-phase catalysts and nanoparticles by using an ionization multi-channel nozzle device so as toprepare sodium 2-hydroxyethanesulfonate, further performing high-temperature high-pressure treatment and concentration so as to prepare sodium taurate, and neutralizing a sodium taurate liquid by using sodium hydrogen sulfite; and in a ceramic nanometer-sized metallomolecular cage component, performing a self-assembling reaction on a three-tooth bridging ligand with sulfur and nitrogen and divalent nickel, palladium or platinum ions so as to establish a cubic metallic-organic cage in Oh symmetry, and performing exchange of hydrogen ions with sodium ions and solvent molecule catalysis simultaneously, so as to obtain the taurine. Mother liquor is subjected to concentration and separation to obtain sodium sulfite which is used as a raw material of an ethylene oxide reaction, an absorption andtransferring carrier of sulfur dioxide and a raw material for neutralizing the sodium taurate liquid. Waste liquid free circulation production of taurine can be achieved.

Method for purifying crude selenium through anhydrous ethanol

Abstract: The invention discloses a method for purifying crude selenium through anhydrous ethanol, and belongs to the technical field of wet metallurgical engineering. The method comprises the steps that a sodium sulfite solution is used for leaching the crude selenium (containing 90%-99% of selenium), wherein the leaching temperature is 50-150 DEG C, the leaching time is 0.5-3 h, and the stirring speed is100-350 r/min; and after leaching, filtering is conducted to obtain a sodium selenosulphate leaching solution, the obtained sodium selenosulphate leaching solution and the excess anhydrous ethanol aremixed and stirred to obtain selenium precipitate, and finally the selenium precipitate is washed, filtered and dried to obtain fine selenium with the purity being 99.99%-99.999%. Metal impurities such as tellurium, lead, copper, silver and gold in leaching slag are further enriched. The anhydrous ethanol is adopted to precipitate the selenium from the sodium selenosulphate solution, thus efficient extraction and purification of the selenium are achieved, and no exhaust gases or waste residues are generated in the whole process.