Papers by Keyword: Sodium Chlorate

Abstract: A new chlorate-based chlorine dioxide generation process was developed by using waste molasses as reductant in the presence of sulfuric acid catalyst. The optimum technological condition was determined as 80 ^oC, 50% sulfuric acid, molasses and sodium chlorite weight ratio of 1:4. The best conversion rate and purity of chlorine dioxide was 73.8% and 95.1%, respectively. Chlorite was found in the reacting mixtures, and major reactions of in process were inferred. The results obtained provides a new way for waste molasses comprehensive utilization and chlorine dioxide generation.

Abstract: In this work, simultaneous absorption of SO₂ and NO from N₂-NO-SO₂ simulated flue gas using sodium chlorate as the additive and urea as the reductant was investigated experimentally in a rotating packed bed. In RPB, various rotational speeds, gas flow rates and liquid flow rates were studied by means of the removal efficiency of SO₂ and NO. The experimental results showed that the removal efficiency of SO₂ was higher than 99.00% under various experimental conditions and, at the same time, the removal efficiency of NO exhibited different results under various experimental conditions. The simultaneous NO removal efficiency of 82.45% and the SO₂ removal efficiency of 99.49% could be obtained under the N₂ flow rate of 0.5 m³/h, SO₂ flow rate of 6 mL/min, the NO flow rate of 4 mL/min, the rotational speed of 460 rpm and the absorbent flow rate of 40 L/h.

Abstract: Preparation of chlorine dioxide by electrocatalytic reduction of sodium chlorate with Ti/IrO₂ anode and Ti cathode was studied in a three-electrode cell without any diaphragm but with a sandwich bath by galvanostatic electrolysis. Classic iodometry was used to determine the concentration of ClO₂ in the electrolyte. The change of space-time yield with current density, the concentration of H₂SO₄, the concentration of NaClO₃, reaction temperature and electrolysis time were studied through single factor experiment in order to determine the optimal conditions of electrolysis. It shows that the optimal conditions of ClO₂ preparation by electrocatalytic reduction of sodium chlorate were: i=60 mA/cm², [H₂SO₄]=4.5 mol/L, [NaClO₃]=1.0 mol/L, T=30 °C, t=30 min. Under these conditions, the space-time yield of ClO₂ reached 1.50 mg/L·s.

Abstract: This paper will conduct a systematic study on method of recovering Ge from pulverized fuel ash in Lincang prefecture, Yunnan province. Details are like this, in view of the fact that Ge contained in pulverized fuel ash is wrapped up by a lot of Silica, Cao, magnesium oxide and is difficult to react with hydrochloric acid, so, first, have the pulverized fuel ash grinded to 200 meshes; then, ammonium fluoride should be put into 85-90°Cdilute sulphuric acid solution to produce hydrogen fluoride so as to destroy silicon dioxide and calcium oxide contained in the pulverized fuel ash. Meanwhile, dilute sulphuric acid solution dissolves magnesium oxide, by doing so, Ge will be released to react with sulfuric acid and produce Sulfuric acid Ge, and Ge will go into the solution；as for low state Ge（e.g,GeO,GeS）contained in the pulverized fuel ash which is difficult to be dissolved by sulfuric acid, sodium chlorate will be used as a kind of oxidant to change bivalence Ge into tetravalence Ge, then dissolve it into the solution, after the liquid-solid separation, sulfuric acid leaching solution rich in Ge will be obtained. Then, tannic acid will be used as precipitant to recover Ge from the leaching solution, and Ge concentrate will be produced through distillation and roasting. After this, put Ge concentrate on hydrochloric acid distillation to get germanium tetrachloride, After going through strenuous evaporation, distillation and hydrolysis, germanium dioxide with high purity will be yield. This paper has conducted conditional tests and discussion on the process parameters which will influence recovery Ge from pulverized fuel ash, including the dosage of Sulfuric acid, ammonium fluoride, sodium chlorate ,tannic acid and extraction time to find out the prior controlling condition of Ge recovery，under this prior condition, Ge leaching rate is as high as 84%，and tannic sinking Ge rate is as high as 98%. The pulverized fuel ash, after recovering Ge, can be used to backfill the mine pit, besides, most of the lixivium after recovering Ge can be recycled, and the rest of it will be released after neutralized up to the standard by lime. This process enjoys the following quality: high Ge recovery rate, less time used during the process ,less consumption of auxiliary material, easier to control the process, avoiding the potential pollution on the environment and lower cost involved in it, therefore, which is a kind of efficient and economic process of recovering Ge from pulverized fuel ash.

Abstract: Based on the mechanism of ClO₃^-/Cl^- reaction system, the kinetics for reaction of sodium chlorate and hydrochloric acid to generate ClO₂ was studied. The rate equation of this reaction system was deduced and simplified as a formula with mixed-order (combination of first-order and second-order) towards ClO₃^-. This rate formula indicates that the initial rate of the reaction is the first-order with respect to ClO₃^-, and the reaction rate is the second-order with respect to ClO₃^- when [ClO₃^-] becomes close to zero. The rate constants of the first-order were determined as 0.0168s^-1(30°C), 0.0221s^-1(40°C), and 0.0279s^-1(50°C), respectively, and that of the second-order were obtained for 0.0019L·mol^-1·s^-1(30°C), 0.0028L·mol^-1·s^-1(40°C), and 0.0060L·mol^-1·s^-1(50°C), respectively. The results of statistic test prove that the rate formula obtained in this work is credible.