Cr (VI) removal and recovery method based on electrochemical oxidation-reduction sequential conversion

A recycling method, electrochemical technology, applied in chemical instruments and methods, contaminated groundwater/leachate treatment, water pollutants, etc., can solve the problem of difficult recovery of chromium resources, large chromium-containing sludge, and high treatment and disposal costs. problems, to achieve the effect of automatic control and equipment, easy automatic control and equipment, and beneficial to recycling

Inactive Publication Date: 2021-01-22
JINAN UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

It can be seen that, for the treatment of neutral Cr(VI) sewage, the above-mentioned two-step treatment method takes a long time, the process is cumbersome, and the adjustment of the pH of the solution needs to consume a large amount of chemicals, resulting in high costs for the treatment and disposal of neutral Cr(VI) sewage. Problems such as difficulty in recycling chromium resources
In addition, this method is easy to produce a large amount of chromium-containing sludge and introduce inorganic salt ions, causing secondary pollution to the environment

Method used

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  • Cr (VI) removal and recovery method based on electrochemical oxidation-reduction sequential conversion
  • Cr (VI) removal and recovery method based on electrochemical oxidation-reduction sequential conversion
  • Cr (VI) removal and recovery method based on electrochemical oxidation-reduction sequential conversion

Examples

Experimental program
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Effect test

Embodiment 1

[0027] Using a graphene sponge with a thickness of 5mm as the cathode and anode electrodes, a 5cm-diameter internal filter device based on sequential oxidation-reduction reactions was constructed. The schematic diagram of the device is shown in figure 1 Figure a in. Supply voltage 3.0V, flux 1000L / h / m 2 Under continuous treatment of 5 mg / L Cr(VI) solution (pH 7), no Cr ions (including Cr(VI) and Cr(III)) can be detected in the effluent within 24 hours of continuous operation. When the total Cr ion concentration in the effluent water is higher than 50 μg / L, immediately turn off the pump and the voltage power supply, then connect the cathode and anode of the device to the positive and negative poles of the power supply respectively, apply a reverse voltage of 3V, and let it stand for 10 minutes to react. The solution in the electrode is discharged from the reactor to obtain a Cr(III) solution that is about 3000 times concentrated (compared with the concentration of Cr(VI) in th...

Embodiment 2

[0031] Using graphitized carbon felt with a thickness of 10mm as the cathode and anode electrodes, an in-electrode filter electrochemical device with a diameter of 10cm based on sequential oxidation-reduction reactions was constructed. Supply voltage 3.5V, flux 1000L / h / m 2 Under continuous treatment of 5 mg / L Cr(VI) solution (pH 8), no Cr ions (including Cr(VI) and Cr(III)) can be detected in the effluent within 40 hours of continuous operation. When the total Cr ion concentration in the effluent water is higher than 50 μg / L, immediately turn off the pump and the voltage power supply, then connect the cathode and anode of the device to the positive and negative poles of the power supply respectively, apply a reverse voltage of 3V, and let it stand for 5 minutes to react. The solution in the electrode is discharged from the reactor to obtain a Cr(III) solution that is about 1500 times concentrated (compared with the concentration of Cr(VI) in the feed water), which is convenien...

Embodiment 3

[0035] Using a graphene sponge with a thickness of 5mm as the cathode and anode electrodes, a 5cm-diameter internal filter device based on sequential oxidation-reduction reactions was constructed. The schematic diagram of the device is shown in figure 1 Figure a in. Investigate the influence of operating supply voltage and flux on Cr(VI) (5mg / L Cr(VI) and pH is 6)) removal ability, such as image 3 As shown in a in the figure: as the supply voltage increases, the Cr(VI) removal performance of the device first increases and then decreases. With a supply voltage of 3-5V, it can achieve no Cr ions in the water within 30 hours of continuous operation ( Including Cr(VI) and Cr(III)) detection. The device was compared at 3.0V and flux 500-7000L / h / m 2 Under the treatment performance of Cr(VI) sewage (sewage treatment capacity = flux * treatment time * electrode area), such as image 3 As shown in b in the figure: as the flux increases, the device's Cr(VI) processing capacity first...

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Abstract

The invention discloses a method for removing and recovering hexavalent chromium in a neutral water body based on oxidation-reduction reaction sequential conversion of filtration system in electrode.According to the method, a sequential oxidation reduction electrochemical method is adopted, Cr (VI) reduction and Cr (III) in-situ precipitation in the neutral sewage are achieved through a cathode Cr (VI) reduction and Cr (III) in-situ precipitation mechanism, and no Cr ions can be detected in effluent; and when a cathode is excessively passivated by Cr (OH) 3 and the concentration of Cr ions inthe effluent exceeds the standard, Cr (OH) 3 precipitates on the surface of the cathode are dissolved by adopting the sequential reduction-oxidation electrochemical method, so that regeneration of the cathode and concentration and resource recovery of Cr pollutants are realized in situ. The method disclosed by the invention is low in operation cost, dose not need the addition of chemical agents,easy to realize automatic control and equipment-based application, suitable for online treatment of medium and small-scale neutral Cr (VI) sewage, and particularly suitable for in-situ remediation ofCr (VI) polluted drinking water sources and underground water.

Description

technical field [0001] The invention belongs to the field of hexavalent chromium sewage treatment, and in particular relates to a method for removing and recovering hexavalent chromium in neutral water bodies based on the sequence conversion of oxidation-reduction reactions in an electrode inner filter system. Background technique [0002] Hexavalent chromium (Cr(VI)) can exist stably in the environment, has strong solubility and mobility in water, is easily absorbed and enriched by living organisms, and is very carcinogenic and carcinogenic to living organisms. mutation. Cr(VI) compounds are listed as priority pollutants and A-level human carcinogens by the US Environmental Protection Agency. my country's "Drinking Water Hygienic Standards" (GB5749-2006) stipulates that the concentration limit of Cr(VI) in drinking water is 50 μg / L. Chromium is widely used in electroplating, mining, tanning, electronic equipment manufacturing and other industries. Due to improper treatmen...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F1/461C02F101/22C02F103/06
CPCC02F1/4672C02F1/4676C02F2101/22C02F2103/06
Inventor 刘海张佳春秀王文宜皮霜玉王旸
Owner JINAN UNIVERSITY
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