A Cr nanopowder for rapid and efficient degradation of Cr(VI) wastewater and a preparation method thereof

Abstract

The invention discloses a Cr nano powder for rapidly and efficiently degrading Cr(VI) wastewater and a preparation method thereof. The invention comprises: dissolving CrCl3 / NiCl2 / FeCl3 in water according to a certain atomic ratio x / y / z (x=10-60; y / z=2 / 3; y+z=100-x) to form a mixed solution with a concentration of ≤10g / 100ml; adding carbon black powder with a particle size of ≥30μm, with the mass ratio of carbon black to a mixture (CrCl3+NiCl2+FeCl3) being 1 / 1, and forming a mixed suspension after high-speed stirring; adding NaOH or ammonia water to the mixed suspension to adjust the pH value to ≥12; heating to 60-85°C, adding N2H4H2O after fully mixing, continuing stirring, standing and settling, cooling, and obtaining a suspension of black Cr@C alloy composite powder; magnetically separating the composite powder and washing it with anhydrous ethanol for multiple times; repeatedly demagnetizing the powder for more than 3 times in a magnetic field with a magnetic field strength of 0.01T-0.3T; and recovering the powder with a filter screen or a magnet. The present invention prepares a powder with good Cr(VI) wastewater treatment activity, strong antioxidant ability and stronger magnetism by modifying the nano Cr component; the powder can be stored and used for a long time, and is easy to disperse when treating wastewater and easy to remove after treatment.

Description

Technical Field

[0001] The invention belongs to the field of heavy metal ion wastewater treatment, and specifically relates to a metal nano powder for heavy metal ion Cr(VI) wastewater treatment and a preparation method thereof. Background Art

[0002] Compared with traditional environmental remediation technologies, surface effects, volume effects, quantum size and macroscopic quantum tunneling effects give nanomaterials unique properties, such as huge specific surface area, super strong adsorption, catalysis and chelation capabilities, which not only overcome the shortcomings of traditional remediation technologies, but also show extremely high remediation efficiency. Therefore, the use of nanomaterials to remediate polluted water and soil has become a research hotspot in the current environmental field.

[0003] Nano-zero-valent iron particles show good treatment effects in treating pollutants such as chlorinated organic matter, polychlorinated biphenyls, inorganic non-metallic ions, and heavy metal ions. However, nano-zero-valent iron has no significant effect in removing Cr(VI). CrNiFe alloy powder has a good removal effect on Cr(VI). At the same time, the powder has certain magnetic properties, which is convenient for removing it with a magnetic field after treating wastewater. Summary of the invention

[0004] The purpose of the present invention is to provide a Cr nanopowder and a preparation method thereof for rapidly and efficiently degrading Cr(VI) wastewater in view of the above problems. The powder can remove heavy metal ions after being added to heavy metal ion wastewater in proportion and stirred for a period of time.

[0005] The present invention is achieved in that the preparation method is as follows:

[0006] (1) Dissolve CrCl3 / NiCl2 / FeCl3 in water at a certain atomic ratio of x / y / z (wherein x=10-60; y / z=2 / 3; y+z=100-x) to form a mixed solution, wherein the concentration of the mixed solution is ≤10g / 100ml; (2) Add carbon black powder (powder particle size ≥30μm) to the mixed solution, and the mass ratio of carbon black powder to the mixture (CrCl3+NiCl2+FeCl3) is 1 / 1. Stir at high speed for 5 minutes to form a mixed suspension; (3) Add NaOH or ammonia water to the mixed suspension to adjust the pH value of the mixed suspension to ≥12; (4) Heat to 60-85°C, add N2H4.H2O after fully mixing, and continue stirring for 60-120 minutes, let it stand and cool to obtain a suspension of black Cr@C alloy composite powder; (5) After magnetic separation of the composite powder, wash it with anhydrous ethanol for multiple times; (6) Demagnetize the powder repeatedly in a magnetic field with a magnetic field strength of 0.01T-0.3T for more than 3 times; (7) The powder can be easily recovered using a filter or a magnet.

[0007] The beneficial effects of the present invention are as follows: (1) by modifying the nano-Cr component, the prepared powder has good Cr(VI) wastewater treatment activity; (2) the powder has strong antioxidant capacity and can be stored and used for a long time; (3) the magnetic properties of the powder designed by the present invention are stronger than those of pure iron powder, and it is easy to remove the wastewater by magnetic field or filter after treatment; (4) the powder is adsorbed on the surface of the carbon black powder and is easy to disperse in the wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a diagram showing the effect of the magnetic powder prepared in Examples 1 to 3 on degrading Cr(VI) wastewater. DETAILED DESCRIPTION

[0009] Example 1: A magnetic powder for efficiently degrading Cr(VI) wastewater and a preparation method thereof, wherein the preparation method is as follows:

[0010] Preparation of main raw materials: chromium chloride (CrCl3), ferric chloride (FeCl3), nickel chloride (NiCl2). Steps: (1) dissolving CrCl3 / NiCl2 / FeCl3 in water at a certain atomic ratio of 60 / 16 / 24 to form a mixed solution with a solution concentration of 10g / 100ml; (2) adding carbon black powder (powder particle size ≥ 50μm) to the mixed solution with a mass ratio of carbon black to the mixture (CrCl3+NiCl2+FeCl3) of 1 / 1. Stir at high speed for 5 minutes to form a mixed suspension; (3) Add NaOH or ammonia water to the mixed suspension to adjust the pH of the mixed suspension to 13; (4) Heat to 65°C, add N2H4.H2O and continue stirring for 90 minutes after fully mixing, let it stand and cool to obtain a suspension of black Cr@C alloy composite powder; (5) After magnetic separation of the composite powder, wash it with anhydrous ethanol for 10 times; (6) Demagnetize the powder repeatedly in a magnetic field with a magnetic field strength of 0.3T for more than 3 times; (7) Use a filter to recover the powder Cr 60 Ni 16 Fe 24 Nano powder.

[0011] Example 2: A magnetic powder for efficiently degrading Cr(VI) wastewater and a preparation method thereof, wherein the preparation method is as follows:

[0012] Preparation of main raw materials: chromium chloride (CrCl3), ferric chloride (FeCl3), nickel chloride (NiCl2). Steps: (1) dissolving CrCl3 / NiCl2 / FeCl3 in water at a certain atomic ratio of 40 / 24 / 36 to form a mixed solution with a solution concentration of 10g / 100ml; (2) adding carbon black powder (powder particle size ≥ 50μm) to the mixed solution with a mass ratio of carbon black to the mixture (CrCl3+NiCl2+FeCl3) of 1 / 1. Stir at high speed for 5 minutes to form a mixed suspension; (3) Add NaOH or ammonia water to the mixed suspension to adjust the pH of the mixed suspension to 13; (4) Heat to 85°C, add N2H4.H2O and continue stirring for 90 minutes after fully mixing, let it stand and cool to obtain a suspension of black Cr@C alloy composite powder; (5) After magnetic separation of the composite powder, wash it with anhydrous ethanol for 10 times; (6) Demagnetize the powder repeatedly in a magnetic field with a magnetic field strength of 0.3T for more than 3 times; (7) Use a filter to recover the powder Cr 40 Ni 24 Fe 36 Nano powder.

[0013] Example 3: A magnetic powder for efficiently degrading Cr(VI) wastewater and a preparation method thereof, wherein the preparation method is as follows:

[0014] Preparation of main raw materials: chromium chloride (CrCl3), ferric chloride (FeCl3), nickel chloride (NiCl2). Steps: (1) dissolving CrCl3 / NiCl2 / FeCl3 in water at a certain atomic ratio of 20 / 32 / 48 to form a mixed solution with a solution concentration of 10g / 100ml; (2) adding carbon black powder (powder particle size ≥ 50μm) to the mixed solution with a mass ratio of carbon black to the mixture (CrCl3+NiCl2+FeCl3) of 1 / 1. Stir at high speed for 5 minutes to form a mixed suspension; (3) Add NaOH or ammonia water to the mixed suspension to adjust the pH of the mixed suspension to 13; (4) Heat to 80°C, add N2H4.H2O and continue stirring for 60 minutes after fully mixing, let it stand and cool to obtain a suspension of black Cr@C alloy composite powder; (5) After magnetic separation of the composite powder, wash it with anhydrous ethanol for 10 times; (6) Demagnetize the powder repeatedly in a magnetic field with a magnetic field strength of 0.3T for more than 3 times; (7) Use a filter + magnetic field to recover the powder Cr 20 Ni 32 Fe 48 Nano powder.

[0015] Figure 1 The effect diagram of Cr(VI) wastewater degradation by Cr nanopowder prepared in Examples 1, 2 and 3, wherein (a) is the Cr(VI) wastewater stock solution, and (b) is the Cr prepared in Example 1. 60 Ni 16 Fe24 The effect diagram of nano powder degrading Cr(VI) wastewater, (c) is the Cr prepared in Example 2 40 Ni 24 Fe 36 The effect diagram of nano powder degrading Cr(VI) wastewater, (d) is the Cr prepared in Example 3 20 Ni 32 Fe 48 The effect of nanopowder on degradation of Cr(VI) wastewater.

[0016] The present invention is not limited to the above embodiments. For those skilled in the art, several improvements and modifications may be made without departing from the concept and principle of the present invention. These improvements and modifications are also considered to be within the protection scope of the present invention.

Claims

1. A method for preparing Cr nanopowder for rapid and efficient degradation of Cr(VI) wastewater, characterized in that: The preparation method steps are as follows: (1) Dissolve CrCl3 / NiCl2 / FeCl3 in water at a certain atomic ratio of Cr / Ni / Fe x / y / z to form a mixed solution, where x = 10-60; y / z = 2 / 3; y+z = 100 - x; (2) adding carbon black powder to the mixed solution, wherein the mass ratio of carbon black powder to the mixture of CrCl3+NiCl2+FeCl3 is 1 / 1, and stirring at high speed to form a mixed suspension; (3) Add NaOH or ammonia water to the mixed suspension to adjust the pH of the mixed suspension to ≥ 12; (4) Heating to 60-85°C, adding N2H4H2O and stirring for 60-120 min after thorough mixing, and cooling by precipitation to obtain a suspension of black Cr@C alloy composite powder; (5) After magnetic separation of the composite powder, wash it several times with anhydrous ethanol; (6) The cleaned composite powder is repeatedly demagnetized more than three times in a magnetic field with a magnetic field strength of 0.01T~0.3T; (7) Recover the Cr nanopowder using a filter or a magnet.

2. The method for preparing Cr nanopowder for rapidly and efficiently degrading Cr(VI) wastewater according to claim 1, characterized in that: The concentration of the mixed solution in step (1) is ≤10 g / 100 ml.

3. The method for preparing Cr nanopowder for rapidly and efficiently degrading Cr(VI) wastewater according to claim 1, characterized in that: The particle size of the carbon black powder in step (2) is ≥30µm.

4. A Cr nanopowder for rapidly and efficiently degrading Cr(VI) wastewater prepared according to any one of the methods of claims 1 to 3.

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