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Device and method for recovering activity of zero-valent iron passivated in Cr pollution removal process

A zero-valent iron and active technology, which is applied in chemical instruments and methods, water pollutants, water/sewage treatment, etc., can solve the problems of poor operability, reduced processing capacity, and high processing costs, and achieves a high degree of automation, Easy operation and cost-saving effect

Active Publication Date: 2013-08-07
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the problem in the application process of zero-valent iron is that the passivation of zero-valent iron leads to the reduction of processing capacity.
The currently reported zero-valent iron passivation methods include pickling and ultrasonic treatment, but these methods have problems such as high processing costs, heavy workload, and poor operability to varying degrees.

Method used

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  • Device and method for recovering activity of zero-valent iron passivated in Cr pollution removal process
  • Device and method for recovering activity of zero-valent iron passivated in Cr pollution removal process
  • Device and method for recovering activity of zero-valent iron passivated in Cr pollution removal process

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] In this embodiment, the method for recovering the activity of the passivated zero-valent iron in the process of removing Cr pollution uses an organic plastic reaction tank 1 with an effective volume of 330 ml, which is filled with zero-valent iron filler 2 . Place iron mesh electrodes 3 along the sides of the tank walls parallel to the water flow direction, and place a piece of PVC mesh 5 along the center plane. The effective area of ​​iron mesh electrodes 3 is 60cm 2 . A DC voltage regulator is used as the power supply with an effective voltage of 0-50V and an effective current of 0-5A. In the experiment, artificially synthesized Cr was used to pollute water (Cr, 25mg / L; Na 2 SO 4 ; 0.5g / L), the experimental water intake was carried out in an upflow manner, and the Cr-containing contaminated water flowed in from the bottom of the reaction tank 1 at a flow rate of 4mL / min, and flowed out from the top of the reaction tank 1. When the reaction time is about 170min, it ...

Embodiment 2

[0033] In this embodiment, the method for recovering the activity of the passivated zero-valent iron in the process of removing Cr pollution uses an organic plastic reaction tank 1 with an effective volume of 72 ml, which is filled with zero-valent iron filler 2 . Place the iron mesh electrodes 3 along the sides of the tank walls perpendicular to the water flow direction, and place a piece of PVC mesh 5 along the center surface. The effective area of ​​the iron mesh electrodes 3 is 12cm 2 . A DC voltage regulator is used as the power supply with an effective voltage of 0-50V and an effective current of 0-5A. Other conditions are the same as example 1. With the continuous progress of the removal reaction, the removal rate of Cr(VI) decreased continuously, and when it reached 106min, the removal rate dropped to 44.21%. After energizing the iron grids at both ends with 10v for 4 minutes, turn the positive and negative poles upside down and energize for another 4 minutes. Depen...

Embodiment 3

[0035] In this embodiment, the method for recovering the activity of the passivated zero-valent iron in the Cr pollution removal process, the reaction tank 1 is the same as that of the second embodiment, and iron grid electrodes 3 are respectively placed along the sides of the tank walls parallel to the water flow direction, and a piece is placed along the center plane. PVC mesh, iron mesh electrode 3 effective area 24cm 2 . The Cr-polluted water was prepared with groundwater from Tsinghua University, and the influent flow rate was 0.8ml / min, and other conditions were the same as in Example 2. The initial removal rate of the reactor was 97.6%, and the removal rate continued to decrease as the reaction progressed. A total of 3 electrochemical depassivation operations were introduced in the experiment. After energizing at a voltage of 10v for 10 minutes, the positive and negative electrodes were reversed and then energized for 10 minutes. Depend on Figure 4 It can be seen th...

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Abstract

The invention discloses a device and a method for recovering activity of zero-valent iron passivated in a Cr pollution removal process. The device comprises a reaction tank, wherein a water inlet is formed in the bottom of the reaction tank; a water outlet is formed in the top of the reaction tank; iron net electrodes and zero-valent iron fillers are placed in the reaction tank; and the iron net electrodes are connected with a power supply. The method comprises the following steps that: when the zero-valent iron fillers are passivated, the power supply powers the iron net electrodes; the positive electrode and negative electrode are reversed and powered for the same time; a certain electric field is applied; a large amount of hydrogen can be separated out of the surface of one side of a cathode; a great number of bubbles burst out from the surfaces of the zero-valent iron fillers, and have effects of peeling and clearing attachment layers, so that a passivation layer on the surface of the iron is peeled off; and a great number of iron ions on one side of each anode are dissolved out to peel off precipitates on the surfaces of the zero-valent iron fillers. With the adoption of the device and the method, the material is not required to be replaced, and thus the cost is saved; secondary pollution of the iron ions cannot be caused; the Cr removal efficiency of a reactor after de-passivation is high; and the service lives of the fillers are long after de-passivation.

Description

technical field [0001] The invention relates to the technical field of Cr removal in groundwater, in particular to a device and method for restoring the activity of zero-valent iron passivated during the Cr pollution removal process. Background technique [0002] At present, water resources in my country and even in many regions of the world are polluted by Cr to varying degrees, which seriously threatens the safety of drinking water for residents. Cr pollution in water resources has attracted more and more attention. Cr mainly comes from processes such as metal plating, leather manufacturing, and pigment production, and is a common pollutant in groundwater in industrial areas. Cr(VI) has relatively stable chemical properties in soil and water, exists in aqueous solution in the form of ions, is not easily degraded by microorganisms, and can be enriched in vegetation and organisms. Cr(VI) can induce allergies. After entering the human body, it can accumulate in certain organ...

Claims

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Application Information

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IPC IPC(8): C02F1/461C02F101/22
Inventor 刘翔李淼卢欣
Owner TSINGHUA UNIV
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