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A treatment method and recycling technology, applied in the field of waste liquid recycling, can solve environmental hazards and other problems, and achieve the effects of high recovery rate, easy operation, and low recycling cost
Inactive Publication Date: 2012-12-05
NANJING COLLEGE OF CHEM TECH
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[0021] The above treatment technology is only for silver and mercury, in fact COD Cr There are also a large amount of trivalent chromium, ferric iron, hydrogen and sulfate ions in the waste liquid. These substances will also cause serious harm to the environment. They should be treated as resources and recycled.
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Embodiment 1
[0049] Take COD Cr Measure waste liquid 1000mL, add 0.9581g sodium chloride, fully react, generate 2.1359g silver chloride, add appropriate amount of concentrated sulfuric acid after filtering, washing and drying, heat to 320°C, react for 20min, filter, wash and dry, the generated Hydrogen chloride gas is absorbed with lye to obtain 1.4193g of product silver sulfate.
Embodiment 2
[0051] Take COD Cr Measure waste liquid 1000mL, add 1.9057g sodium chloride, fully react, generate 2.0641g silver chloride, add appropriate amount of concentrated sulfuric acid after filtering, washing and drying, heat to 320°C, react for 21min, filter, wash and dry, the generated Hydrogen chloride gas is absorbed with lye, obtains product silver sulfate 1.4001g.
Embodiment 3
[0053] Take COD Cr Measure waste liquid 1000mL, add 2.8568g sodium chloride, fully react, generate 2.0789g silver chloride, filter, wash, dry, add appropriate amount of concentrated sulfuric acid, heat to 320°C, react for 22min, filter, wash, dry, the generated Hydrogen chloride gas is absorbed with lye to obtain product silver sulfate 1.4073g.
[0054] Table 2 Test results
[0055]
[0056] As can be seen from Table 2, the method has a high recovery rate, which can reach more than 80.6%; the recovery rate is stable, all around 80%; and no secondary pollution will be produced.
[0057] What adopted in the embodiment is the waste liquid produced by the national standard GB11914-89 method, containing about 2.35g of mercury sulfate in every liter of waste liquid. The implementation results are shown in Table 3.
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Abstract
The invention discloses a method for recovering four heavy metals, namely silver, mercury, iron and chromium, and a sulfuric acid from CODCr (chemical oxygen demand chromium) measurement waste liquid, and belongs to the technical field of the resource treatment of waste liquid. The method mainly comprises a technology of recovering Ag2SO4 by using a NaCl-H2SO4 method, a technology of recovering the H2SO4 by using a strongly basic anion exchange resin acid retardation principle, a technology of recovering Hg2SO4 by using a Na2S-HCl-NaOH-H2SO4 method and a technology of recovering a Fe2O3, Cr2O3 and Na2SO4 solution by using a sequential precipitation method. The method provided by the invention is simple in process and is easy to operate; the recovery rates of the silver sulfate and the mercury sulfate are high and respectively reach 80.6% and 87.8%; the recovery rate of the sulfuric acid reaches 82%; the secondary pollution cannot be caused; the product quality is good; the silver sulfate and the mercury sulfate which are recovered are both up to the standard of a commercially available reagent and can be recycled in CODCr measurement; and the recovery cost is low.
Description
technical field [0001] The invention belongs to the technical field of waste liquid resource treatment, and in particular relates to recovery of COD Cr Method for determination of silver, mercury, iron, chromium four heavy metals and sulfuric acid in waste liquid. Background technique [0002] Potassium dichromate (K 2 Cr 2 o 7 ) as the oxidant measured chemical oxygen demand expressed as COD Cr . Determination of COD by Silver Sulfate as Potassium Dichromate Cr The catalyst only plays a catalytic role without being consumed. The waste liquid after determination contains a large amount of silver ions, and soluble silver salts are toxic pollutants in waste water. Mercury sulfate, as a chloride ion masking agent, can form complexes with chloride ions in water samples, which are not consumed and still exist in the waste liquid after measurement. Hexavalent chromium is completely converted into trivalent chromium after the reaction, but the amount of the substance remains...
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