Method for reducing hexavalent chromium through micromolecular diketone-ultraviolet light

A technology of hexavalent chromium and small molecules, applied in the field of water treatment, can solve the problems of complex pollution sources of hexavalent chromium and lack of prevention and control technology, and achieve the effects of wide pH range, simple operation and high industrial application prospect.

Active Publication Date: 2016-07-06
NANJING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The pollution sources of hexavalent chromium are complex, and the forms change in various forms during the migration process, mostly CrO 4 2- 、Cr 2 o 7 2- form, lack of effective control technology, and Cr(III) can be removed by simple methods such as alkali precipitation
However, the structure and chemical properties of hexavalent chromium are completely different from those of organic dyes. It is not yet known whether it can form a photoexcited complex with a small molecule diketone and undergo photoinduced electron transfer.
At present, there is no report on the method of reducing Cr(VI) in water by using UV / small molecule diketone method (UV / diketone)

Method used

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  • Method for reducing hexavalent chromium through micromolecular diketone-ultraviolet light
  • Method for reducing hexavalent chromium through micromolecular diketone-ultraviolet light
  • Method for reducing hexavalent chromium through micromolecular diketone-ultraviolet light

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Embodiment 1UV / diketone is to Cr (VI) reducing effect experiment

[0024] Add the Cr(VI) stock solution into several 25mL colorimetric tubes, and then add the small molecule diketones AA, BD, HD, Na 2 SO 3 and TiO 2 , the final concentration of Cr(VI) (in units of K 2 CrO 7 In Cr(VI))) diluted to 20mg / L, and small molecular diketones AA, BD, HD, and reducing agent Na in the colorimetric tube 2 SO 3 The final concentration is 1.0mM, TiO 2 The final concentration was 1g / L, and then poured into the 25mL reaction tube of the light reaction device.

[0025] The photochemical device used in this implementation case is attached to the specification of the patent CN102491450B figure 1 , 2 As shown, the instrument operation steps are the same as those in Example 1 of this patent.

[0026] This embodiment uses a 300W medium pressure mercury lamp, and the light intensity at the reaction solution is 5mW / cm 2 , light irradiation reaction 60min, sampling once every 10min to...

Embodiment 2

[0028] Example 2 Different initial concentrations of Cr (VI) affect the UV / AA reduction treatment effect test

[0029] The illumination device and illumination conditions of the present embodiment are the same as the implementation case 1, but the hexavalent chromium concentration added in the colorimetric tube is 12-18mg / L, and the AA concentration is 0.1mM, and the reaction result is as follows figure 2 shown.

[0030] Depend on figure 2 The photoreduction effect can be seen. When the concentration of AA is constant, the lower the concentration of Cr(VI) is, the shorter the time required for photoreduction to trivalent chromium is, and the 100% reduction of Cr(VI) can be completed within half an hour, but at different concentrations The photoreduction rate of Cr(VI) changed little, that is, UV / AA had better reduction effect on different initial concentrations of Cr(VI).

Embodiment 3

[0031] Example 3 Different initial pH effects test on the effect of UV / AA reduction treatment

[0032] The illumination device and illumination conditions of this embodiment are the same as those in Example 1, but the concentration of Cr(VI) added is 20 mg / L, and the concentration of AA is 0.1 mM. In addition, the pH of the solution is adjusted to 3.1 and 4.1 in sequence with perchloric acid and sodium hydroxide. , 5.0 and 6.1, the reaction results are shown in 3.

[0033] Depend on image 3 It can be seen that under moderately acidic conditions, UV / AA has a faster photoreduction effect on hexavalent chromium, and the reduction efficiency is less affected by pH, and, as the light reaction proceeds, the pH in the solution gradually increases. After UV60min, the pH of the solution is 1-2 higher than the initial pH (such as Figure 4 shown), which indicates that the hydrogen ions in the solution will be consumed in the process of UV / AA photoreduction of hexavalent chromium, and...

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Abstract

The invention discloses a method for reducing hexavalent chromium through micromolecular diketone-ultraviolet light. According to the method, micromolecular diketone with the final concentration of 0.1-1 mM is put in water containing hexavalent chromium, the pH of the solution is regulated to be 3-6, the solution is placed under an ultraviolet light source for irradiation, and then hexavalent chromium in the water can be reduced into trivalent chromium. According to the UV/micromolecular diketone system established through the method, hexavalent chromium in the water can be quickly reduced into trivalent chromium which is low in toxicity and easier to remove through a physical method; the reaction conforms to the zero order kinetics, and the removal rate of hexavalent chromium is tens of that obtained through a UV/TiO2 method; a homogeneous reaction is performed in the method, operation is simple and convenient, and compared with the UV/TiO2 method and the like, the solution pH applicable range is broader, and the method is little affected by co-existing ions in the solution and can be widely applied to treatment of industrial wastewater containing hexavalent chromium.

Description

technical field [0001] The invention relates to the field of water treatment, in particular to a method for reducing hexavalent chromium by using small molecule diketone-ultraviolet light. Background technique [0002] Chromium is an important metal element with properties such as hardness, wear resistance, high temperature resistance, and corrosion resistance. It is widely used in production. During the production and use of chromium, a large amount of chromium-containing wastewater will be generated, which will endanger environmental safety. Chromium in water mainly exists in the form of hexavalent (Cr(VI)) and trivalent (Cr(III)), of which the toxicity of hexavalent chromium is very high, which is tens to hundreds of times that of trivalent chromium, and skin contact may cause Inherited gene defects, may cause cancer if inhaled, and have persistent danger to the environment. In view of the hazards of hexavalent chromium, the U.S. Environmental Protection Agency (EPA) h...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F1/32C02F1/70C02F101/22
CPCC02F1/32C02F1/70C02F2101/22C02F2305/00
Inventor 张淑娟吴兵党吴惬张国洋杨明辉宋孝杰
Owner NANJING UNIV
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