Method for treatment of electroplating chromium-containing wastewater by periodic polarity reversal

A chromium wastewater, periodic technology, applied in the direction of metallurgical wastewater treatment, water/sewage treatment, chemical instruments and methods, etc., can solve the problems of reduced current efficiency, poor precipitation effect, increased energy consumption, etc., achieve stable operation, prevent electrode Passivation, the effect of reducing construction cost and operating cost

Inactive Publication Date: 2017-10-13
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, during operation, the electrode plate is easily passivated due to the untimely migration of metal ions electrolyzed on the surface, which reduces the current efficiency and increases energy consumption.
In addition, only using metal iron as the electrode will easily cause disadvantages such as high chroma and poor precipitation effect after electrolysis

Method used

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  • Method for treatment of electroplating chromium-containing wastewater by periodic polarity reversal
  • Method for treatment of electroplating chromium-containing wastewater by periodic polarity reversal
  • Method for treatment of electroplating chromium-containing wastewater by periodic polarity reversal

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0046] The chromium content of electroplating wastewater is 100mg / L, the pH is adjusted to 5, the conductivity is 500μs / cm, the average electrolysis time is 20min, iron electrodes are used, the distance between the plates is 0.6cm, the average current density is 10μs / cm, and DC power is used. The pole inversion cycle is 5min / time, and samples are taken every 15min, and the absorbance is measured after 45min of precipitation. As the reaction progresses, Cr 6+ The removal rate gradually increased and stabilized after 30min, and a total of 180min was reacted. At this time, Cr 6+ The removal rate reaches 99.8%.

Embodiment 2

[0050] The chromium content of electroplating wastewater is 100mg / L, the pH is adjusted to 6, the conductivity is 700μs / cm, the average electrolysis time is 18min, and the arrangement of iron and aluminum plates is adopted. The distance between the plates is 1.0cm, the average current density is 20μs / cm, the DC power supply is used, the cycle of inversion is 5min / time, the samples are taken every 15min, and the absorbance is measured after 45min of precipitation. As the reaction progresses, Cr 6+ The removal rate gradually increased and stabilized after 30min, and a total of 180min was reacted. At this time, Cr 6+ The removal rate reaches 99.9%, and the chroma removal rate is 99.8%.

Embodiment 3

[0054] The chromium content of electroplating wastewater is 100mg / L, the pH is adjusted to 7, the conductivity is 1000μs / cm, the average electrolysis time is 15min, and the arrangement of iron and aluminum plates is adopted. The distance between the plates is 1.5cm, the average current density is 30μs / cm, the DC power supply is used, the cycle of inversion is 5min / time, the samples are taken every 15min, and the absorbance is measured after 45min of precipitation. As the reaction progresses, Cr 6+ The removal rate gradually increased and stabilized after 30min, and a total of 180min was reacted. At this time, Cr 6+ The removal rate reaches 99.9%, and the chroma removal rate is 99.8%.

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Abstract

The invention relates to a method for treatment of electroplating chromium-containing wastewater by periodic polarity reversal. The method adopts the steps of: adjusting the pH of electroplating chromium-containing wastewater to 5-7 and the conductivity to 500-2000micros/cm, then inserting pole plates, introducing direct current, carrying out electrocoagulation reaction and periodically reversing the pole plate polarity to electrolyze wastewater, then letting the mixed solution enter a sedimentation tank, recycling the supernatant, and using the precipitated floc as the raw material for preparation of alloy. Compared with the prior art, periodic polarity reversal adopted by the invention can make anode dissolved metal ions better diffuse into water, improves the mass transfer efficiency, alleviates concentration polarization, and can overcome the problems of low current efficiency, electrical energy waste, low treatment efficiency and the like caused by passivation, in addition by a mixed anode method, iron and aluminum metals can be dissolved at anode simultaneously, the floc undergoes coprecipitation, the flocculation effect is better, the effluent water is clear and transparent, has a chromium content of less than 0.01mg/L, and is recyclable.

Description

technical field [0001] The invention relates to a treatment method for chromium-containing wastewater in an electroplating workshop, in particular to a method for efficiently treating electroplating chromium-containing wastewater by periodically inverting mixed anode electroflocculation methods. Background technique [0002] Because hexavalent chromium is highly carcinogenic to the human body, long-term exposure can cause dermatitis, damage the liver and kidney circulation, and even cause serious damage to nerve tissue. Studies have found that hexavalent chromium (such as CrO 4 2- ) has high water solubility and mobility, and its structure is similar to that of sulfate (SO 4 2- ) similarly, hexavalent chromium can overcome the cell osmotic resistance and enter the cell through the transport route of sulfate radical. The hexavalent chromium entering the cell can be reduced to trivalent chromium through intracellular enzyme action; during this process, the redox substances...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F1/463C02F103/16
CPCC02F1/463C02F2103/16
Inventor 时鹏辉邱海俊刘昊林秦欣王旭杨玲霞
Owner SHANGHAI UNIVERSITY OF ELECTRIC POWER
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