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Technique of Producing Na2Cr2O7 from Chemosynthesis Aluminum-foil Industrial Wastewater

Author: XiaoZuoZuo
Tutor: TianXueDa
School: Xiangtan University
Course: Environmental Engineering
Keywords: Cr (Ⅵ) Cr (Ⅲ) Formed foil wastewater Sodium dichromate Resource
CLC: TQ131.1
Type: Master's thesis
Year: 2005
Downloads: 73
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Abstract


Chromium-containing wastewater treatment research significance lies not only in the quality of treated water to meet emission standards , but also because of the recycling of resources . Fully read the chromium-containing wastewater treatment literature at home and abroad on the basis of the Cr-containing wastewater resource formed foil production enterprises and harmless treatment process . The process includes reduction - precipitation - oxidation - Acidification - concentrated preparation of sodium dichromate processes , and were more systematic study of the first three stages of the process conditions . The test results show that under appropriate conditions , chromium recycling rate reaches 79% or more, and sodium dichromate crystal . Preliminary technical and economic analysis . Organics sucrose as a reductant , the Cr (VI ) ( concentration of 27 g / L) reduced to Cr (III ) , obtained by experimentation representing ideal process parameters : the sample of 100 mL of water , sucrose in an amount of 2.6 g , the reaction temperature 97 ℃, the reaction time of 8 min. Reduction rate of 98.9% . Precipitation of Cr (Ⅲ) ( Cr (Ⅵ) produced by the reduction of Cr (Ⅲ) and water samples had already Cr (III ) ( concentration of 20 g / L ) ) . The test ideal process parameters : the reaction temperature is maintained at about 60 ~ 70 ℃ , 100 mL of water samples consumes NH 4 HCO 3 24 g of , NaOH consumption of 15 g , get Cr (OH) 3 precipitation of 8.69 g ; 93.9% of the Cr (III ) removal . Strong alkaline conditions with H 2 O 2 Cr (OH) 3 Cr (Ⅲ) in the oxidation of CrO 4 2 - . The ideal process parameters: 8.69 g of Cr ( OH ) 3 , when maintained at a pH of 13.5, and the reaction time was 40 minutes , consumption of 29 mL of H 2 O < sub> 2 , 14.6 g NaOH, the oxidation rate of 92.1% . 4 H 2 SO 4 Adjust the pH to 2,91.5 % CrO 2 - into Cr 2 O 7 2 - .

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CLC: > Industrial Technology > Chemical Industry > Inorganic compounds, the chemical industry of the metal elements > First Ⅰ group metal elements of inorganic compounds > Inorganic compounds of the alkali metal ( Ⅰ A family ) elements
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