Method for recovering and treating chromium-containing wastewater by using magnetic nanoparticles

A magnetic nanoparticle, recycling technology, applied in the fields of magnetic field/electric field water/sewage treatment, water/sewage treatment, water treatment parameter control, etc., can solve the rising cost of chromium-containing wastewater, secondary organic pollution, and the use effect of magnetic particles Reduction and other problems, to achieve the effect of reducing the cost of pharmaceutical dosage and cost reduction

Pending Publication Date: 2021-07-09
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] First, organic binders such as organic amines, organic acids and their salts are expensive, adding a large amount of organic binders to chromium-containing wastewater will greatly increase the cost of treating chromium-containing wastewater, as described in Example 2 of this patent, The amount of organic binder diethylamine added to treat each ton of wastewater is as high as 8 kg, and the market price is over 100 yuan, which is difficult for industrial application;
[0010] Second, the addition of a large amount of organic binders in chromium-containing wastewater will greatly increase the COD of treated wastewater, causing serious secondary organic pollution, that is, the removal of chromium pollution brings organic pollution, which greatly increases the subsequent COD treatment process. and processing costs;
[0011] Third, adding an organic binder will cause some chromium ions in the chromium-containing wastewater to form complexes with organic amines, organic acids, etc., making it difficult to convert this part of chromium into chromium hydroxide colloidal precipitation, and cannot form magnetic particles-hydroxide Chromium complexes, which reduce the effectiveness of chromium removal or recovery;
[0012] Fourth, adding an organic binder to the chromium-containing wastewater will cause the separated magnetic particles-chromium hydroxide complex to contain a large amount of organic binder, and the magnetic particles and chromium salt solution recovered after magnetic-chromium dissociation also contain more Organic binder, which reduces the recycling effect of magnetic particles and the purity of chromium salt products
[0013] In addition, in the method disclosed in the above-mentioned invention patent, the dissociation of the magnetic particle-chromium hydroxide combination adopts the method of dissolving chromium ions by immersing in a 1 mol / liter sodium hydroxide aqueous solution, wherein the ferromagnetic particles are in this strong In the alkaline aqueous solution, iron ions will be dissolved to form ferrite, which will cause the dissolved chromium salt solution to be polluted by iron, and the recycling effect of magnetic particles will also be reduced. If the alkalinity of the strong alkaline aqueous solution is reduced, the magnetic particles-hydroxide will be caused. Reduced dissociation effect of chromium complexes

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0060] In a 1.5-ton reaction kettle with mechanical stirring and electric heating device, add 1 ton of water and 235 kg of ferric chloride hexahydrate, raise and maintain the temperature to 80 degrees Celsius, add 120 kg of ferrous sulfate heptahydrate, and wait until completely After dissolving, add sodium hydroxide to adjust the pH value at about 11, react for 60 minutes, and the product undergoes solid-liquid separation and repeated washing with water to obtain a magnetic iron containing 100 kg. 3 o 4 The nanoparticle aqueous solution is ready for use.

[0061] TEM image reveals magnetic Fe 3 o 4 The average diameter of nanoparticles is about 10 nanometers, and the magnetic Fe is tested by a vibrating sample magnetometer 3 o 4 The specific saturation magnetization of the nanoparticles is 82emu / g.

[0062] 2. Magnetic separation of chromium in chromium-containing wastewater

Embodiment 2

[0064] In the continuous flow type chromium-containing waste water magnetic nano particle recovery treatment system comprising mixing unit operation (I), mixing unit operation (II), reaction unit operation (III), magnetic separation unit operation (IV) four unit operation devices, Press the flow rate of 2 tons / hour with metering pump, flow into unit operation (I)-(IV) successively successively to the low chromium waste water that contains trivalent chromium 100 mg / liter of tannery A factory, meanwhile, complete following unit operation:

[0065] (1) in mixing unit operation (1)-static pipeline mixer, by the speed of 100 liters / hour, continuously inject the lime aqueous solution that weight concentration ratio is 2%, make the pH value of chromium-containing waste water remain on about 10 all the time, Mix well;

[0066] Among them, the size of the static pipeline mixer is φ100*1000 mm, the internal structure adopts SV type five-section mixing, equipped with lime water dosing me...

Embodiment 3

[0073] In the continuous flow type chromium-containing waste water magnetic nano particle recovery treatment system comprising mixing unit operation (I), mixing unit operation (II), reaction unit operation (III), magnetic separation unit operation (IV) four unit operation devices, Press the flow rate of 2 tons / hour with metering pump, flow into the high-chromium waste water containing trivalent chromium 1500 mg / liter continuously to unit operation (I)-(IV) successively successively, at the same time, complete following unit operation:

[0074] (1) in mixing unit operation (1)-static pipeline mixer, by the speed of 200 liters / hour, continuously inject the lime aqueous solution that weight concentration ratio is 2%, make the pH value of chromium-containing waste water remain on about 9 all the time, Mix well;

[0075] Among them, the size of the static pipeline mixer is φ100*1000 mm, the internal structure adopts SV type five-section mixing, equipped with lime water dosing meter...

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Abstract

The invention provides a method for recovering and treating chromium-containing wastewater by using magnetic nanoparticles, the method comprises the following steps: synthesizing magnetic Fe3O4 nanoparticles by using a special process, forming nanoclusters by combining the magnetic Fe3O4 nanoparticles with chromium hydroxide colloidal particles, and performing magnetic separation operation, thereby directly extracting chromium from the chromium-containing wastewater. Chromium in the chromium-containing wastewater is completely removed, the chromium-containing wastewater is changed into chromium-free wastewater, and no chromium-containing hazardous waste is discharged in subsequent chemical flocculation precipitation. Furthermore, chromic hydroxide in the magnetic Fe3O4 nanoparticle-chromic hydroxide colloid nanocluster combination is oxidized into water-soluble hexavalent chromium acid salt by adopting an oxidizing agent, and recycling of the magnetic nanoparticles and recycling of chromium resources are realized through magnetic separation or solid-liquid separation operation.

Description

technical field [0001] The invention relates to a method for recovering and treating chromium-containing wastewater by magnetic nano particles, which is mainly used in the fields of tanning, electroplating, metallurgy, environmental treatment and the like. [0002] technical background [0003] Industries such as tanning, electroplating and metallurgy discharge a large amount of chromium-containing wastewater and chromium-containing sludge, causing serious waste of resources and environmental pollution. Technical solutions for chromium resource recovery and chromium pollution control are urgently needed. [0004] Traditional methods for treating chromium-containing wastewater include solvent extraction, ion exchange and adsorption, membrane separation, and biological methods. These methods are mainly for trivalent or hexavalent chromium ions in acidic water environments, and have low treatment efficiency and Problems such as high economic cost are difficult to meet the needs ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F1/66C02F1/48C01G37/14C02F101/22
CPCC01G37/14C02F1/488C02F1/66C02F2101/22C02F2209/08
Inventor 不公告发明人
Owner UNIV OF SCI & TECH BEIJING
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