Method for improving reduction removal of pollutants with zero-valent iron

A technology of zero-valent iron and pollutants, applied in the field of water treatment, can solve the problems of low effective utilization rate and low electron selectivity, and achieve the effect of reducing waste generation, improving electron selectivity, and being easy for practical application

Active Publication Date: 2017-03-22
TONGJI UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] In order to overcome the problems of low electron selectivity and low effective utilization rate existing in the existing zero-valent iron technology, the purpose of the present invention is to provide a new method for improving the reduction of zero-valent iron to remove pollutants

Method used

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  • Method for improving reduction removal of pollutants with zero-valent iron
  • Method for improving reduction removal of pollutants with zero-valent iron
  • Method for improving reduction removal of pollutants with zero-valent iron

Examples

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Embodiment 1

[0042] This embodiment is carried out in a stirred tank reactor, and the specific steps are as follows:

[0043] Adjust the pH of the industrial wastewater containing 1mM hexavalent selenium to 6.0, add 1mM ferrous chloride, and continuously enter the stirred tank reactor with a wastewater flow rate of 1m 3 / h, the initial concentration of zero-valent iron in the reactor was 1g / L, the stirring speed was 300rpm, and the reactor was exposed to the air. After 10 hours of reaction, all the zero-valent iron was converted into iron oxides. When other conditions remained the same, but ferrous chloride was not added to the water to be treated, after the reaction was carried out for 15 hours, the concentration of hexavalent selenium in the effluent did not change. According to the concentration of hexavalent selenium in the effluent and its reduction, adding ferrous chloride can increase the utilization rate of zero-valent iron from 78% to 98%, and the electron selectivity from 3.2% to...

Embodiment 2

[0045] The difference between this embodiment and the first embodiment is that air is continuously exposed to the water body during the reaction process, and the waste water flow rate is 1m 3 / h, while the aeration flow rate is 0.6m 3 / h, the ratio is 0.6m 3 air / m 3 water, after reacting for 8 hours, the concentration of hexavalent selenium in the effluent no longer changes. According to the concentration of hexavalent selenium in the effluent and its reduction, adding ferrous chloride can increase the utilization rate of zero-valent iron from 82% to 100%, and the electron selectivity from 2.9% to 6.6%. For details, see figure 2 .

Embodiment 3

[0047] The difference between this embodiment and the second embodiment is the amount of air exposed in the reaction process, and the aeration flow rate is 8m 3 / h, the ratio is 8m 3 air / m 3 water, the stirring speed is 400rpm, after 4 hours of reaction, the concentration of hexavalent selenium in the effluent will not change. According to the concentration of hexavalent selenium in the effluent and its reduction, adding ferrous chloride can increase the utilization rate of zero-valent iron from 85% to 100%, and the electron selectivity from 2.2% to 6.4%. For details, see image 3 .

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Abstract

The invention discloses a method for reduction removal of pollutants with zero-valent iron. With the method, the electron selectivity and the utilization rate of the zero-valent iron can be increased, and meanwhile, the reaction activity of the zero-valent iron can be increased. The method is used for improving the electron selectivity and the utilization rate of the zero-valent iron for reduction removal of the pollutants under the coupling effect of ferrite and oxygen. The method specifically comprises steps as follows: (1) the pH value of a to-be-treated water sample is adjusted to 6.0 or below; (2) ferrite is added to the to-be-treated water sample, the amount of the ferrite is increased with the concentration of the pollutants, and the mole ratio of the ferrite to the pollutants is controlled to range from 0.3 to 1.8; (3) the pretreated water sample enters a reactor containing the zero-valent iron to react with the zero-valent iron, and the reactor is in the aerobic state; (4) then water treated in the reactor enters sedimentation equipment for sedimentation. The step (1) and the step (2) can be conducted in a jet mixer, a rotational flow mixer, a pipeline mixer or other completely mixing equipment. The ferrite includes ferrous chloride, ferrous sulfate or other soluble ferrite.

Description

technical field [0001] The invention belongs to the technical field of water treatment and relates to a method for improving the reduction of zero-valent iron to remove pollutants. Background technique [0002] Due to its low price, easy availability, high safety, no secondary pollution to the environment, and the ability to treat a variety of toxic and harmful pollutants, zero-valent iron has attracted more and more attention in the research and application of sewage treatment. As an active metal, zero-valent iron has a standard electrode potential of E 0 (Fe 2+ / Fe)=-0.440V, has a strong reducing ability, and can replace the metal that comes next in the metal activity sequence table and deposit it on the surface of iron to achieve the purpose of decontamination. When zero-valent iron is in contact with water, due to the existence of cathode (impurity) and anode (Fe 0 ) potential difference resulting in Fe 0 Electrochemical corrosion. Among them, the oxidation reaction...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F1/70C02F1/28C02F101/20
CPCC02F1/281C02F1/288C02F1/705C02F2101/20C02F2209/06
Inventor 关小红秦荷杰杨鸿艺李锦祥张雪莹
Owner TONGJI UNIV
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