KR20130015494A - Method for reduction of hexavalent chromium - Google Patents

Abstract

PURPOSE: A reduction method of six-valent chrome is provided to change six-valent chrome into three-valent chrome through a simple process. CONSTITUTION: A reduction method of six-valent chrome comprises a step of preparing a solution including six-valent chrome, a step of adding organic acid in the solution, and a step of cooling the solution added with the organic acid. The concentration of the organic acid is 60mM or less. The organic acid is formic acid, acetic acid, oxalic acid, citric acid, ethylenediaminetetraacetic acid, humic acid, fulvic acid, or their combination. [Reference numerals] (AA) Embodiment 1; (BB) Embodiment 2; (CC) Embodiment 3; (DD) Embodiment 4; (EE) Embodiment 5; (FF) Embodiment 6

Description

Reduction Method of Hexavalent Chromium {METHOD FOR REDUCTION OF HEXAVALENT CHROMIUM}

A method for reducing hexavalent chromium.

The problems of water quality and soil contamination by heavy metals are getting worse day by day.

Therefore, understanding the oxidation and reduction reaction of heavy metals is considered very important for public hygiene and environmental cleanup.

Among them, hexavalent chromium is widely distributed in nature and produces chromic acid; Chrome plating industry; Manufacturing metal products producing chromium alloys and / or stainless steels; Stainless steel welding industry; Paint and / or pigment production / handling; Manufacturing and / or handling of wood preservatives; It is widely used in many industries such as leather products manufacturing industry.

However, hexavalent chromium is a heavy metal that can cause environmental problems. Therefore, the method of treating hexavalent chromium is drawing attention.

One embodiment of the present invention provides a method for reducing hexavalent chromium as one method for treating hexavalent chromium.

In one embodiment of the present invention, preparing a solution containing hexavalent chromium; Injecting an organic acid into the solution; And it provides a method for reducing hexavalent chromium comprising the step of cooling the solution in which the organic acid is added.

The cooling temperature of the step of cooling the solution in which the organic acid is added may be -10 to -196 ℃.

In the step of introducing the organic acid to the solution, the concentration of the organic acid may be less than 60mM.

The organic acid is formic acid (acetic acid), acetic acid (acetic acid), oxalic acid (oxalic acid), citric acid (citric acid), ethylenediaminetetraacetic acid (EDTA), humic acid (humic acid), fulvic acid ( fulvic acid) or a combination thereof.

The organic acid may be a reducing agent for reducing the hexavalent chromium.

The hexavalent chromium may be reduced to trivalent chromium by the reduction method of hexavalent chromium.

At least 10 mol% of hexavalent chromium in the total amount of hexavalent chromium may be reduced to the trivalent chromium.

The organic acid may be oxalic acid, citric acid, ethylenediaminetetraacetic acid (EDTA), or a combination thereof.

In another embodiment of the present invention, preparing a solution containing hexavalent chromium; Adjusting the pH of the solution to 3 or less; It provides a method for reducing hexavalent chromium comprising; and cooling the solution in which the pH is adjusted to 3 or less.

The cooling temperature of the step of cooling the solution adjusted to 3 or less pH may be -10 to -196 ℃.

The hexavalent chromium may be reduced to trivalent chromium by the reduction method of hexavalent chromium.

At least 10 mol% of hexavalent chromium in the total amount of hexavalent chromium may be reduced to the trivalent chromium.

When using a method for reducing hexavalent chromium according to an embodiment of the present invention, it is possible to reduce toxic hexavalent chromium to trivalent chromium having less toxicity by a simple process.

In addition, when using the reduction method of hexavalent chromium according to an embodiment of the present invention, no other by-products in the process occurs.

Therefore, the reduction method of hexavalent chromium according to an embodiment of the present invention can be widely applied to the fields such as wastewater, groundwater, soil purification including hexavalent chromium.

1 is a graph showing results of Experimental Examples 1 to 6. FIG.
2 is a graph showing results of Comparative Experimental Examples 1 to 6;
3 is a graph showing the results of Experimental Examples 7 to 13, Comparative Experiments 7 to 13, Experimental Example a, and Comparative Experimental Example a.

Hereinafter, embodiments of the present invention will be described in detail. However, it should be understood that the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

In one embodiment of the present invention, preparing a solution containing hexavalent chromium;

Injecting an organic acid into the solution; And it provides a method for reducing hexavalent chromium comprising the step of cooling the solution in which the organic acid is added.

The hexavalent chromium is a highly toxic heavy metal that can cause many environmental problems. According to one embodiment of the present invention, the hexavalent chromium can be reduced to further reduce the environmental problems.

For example, the hexavalent chromium may be reduced to trivalent chromium. The trivalent chromium is less toxic and easier to remove than hexavalent chromium.

Therefore, the hexavalent chromium can be effectively removed from the wastewater, soil, etc. by the method of reducing the hexavalent chromium to trivalent chromium by the reduction method according to an embodiment of the present invention and then precipitating with chromium hydroxide.

In the method for reducing hexavalent chromium according to an embodiment of the present invention, the hexavalent chromium may be effectively reduced by adding an organic acid to a solution containing hexavalent chromium and cooling the same.

In the reduction method according to the embodiment of the present invention, the solution may be frozen when the cooling step is performed. When the solution freezes, most organics and inorganics are concentrated in the semi-liquid layer present around the ice crystals.

In addition, hydrogen may be concentrated in the quasi-liquid layer, and the pH of the quasi-liquid layer may be changed by concentration of the hydrogen ions.

The method for reducing hexavalent chromium according to one embodiment of the present invention may be effective under acidic conditions and / or conditions where the concentration of a reducing agent (eg, organic acid) is increased.

As described above, the reduction reaction of hexavalent chromium effectively occurs when the inorganic (eg hexavalent chromium), organic (eg organic acid) and / or hydrogen ions are concentrated in the semi-liquid layer by the cooling step. It becomes possible.

The cooling temperature of the step of cooling the solution in which the organic acid is added may be -10 to -196 ℃. When the above range is satisfied, the solution freezes, and the concentration of inorganics, organics, and hydrogen in the semi-liquid layer may effectively occur.

In the step of adding an organic acid to the solution, the concentration of the organic acid may be less than 60mM. More specifically, it may be 600 μM or less, 60 μM or less, or 6 μM or less. Since only a small amount of organic acid may be added, the lower limit of the concentration of the organic acid cannot be particularly specified. When the above range is satisfied, hexavalent chromium can be effectively reduced.

The organic acid is formic acid (acetic acid), acetic acid (acetic acid), oxalic acid (oxalic acid), citric acid (citric acid), ethylenediaminetetraacetic acid (EDTA), humic acid (humic acid), fulvic acid ( fulvic acid) or a combination thereof.

More specifically, the organic acid may be oxalic acid, citric acid, ethylenediaminetetraacetic acid (EDTA), or a combination thereof. However, the organic acid is not limited thereto.

The organic acid may serve as a reducing agent for reducing the hexavalent chromium.

In addition, the hexavalent chromium may be reduced to trivalent chromium by the method of reducing hexavalent chromium. Since the description thereof is the same as described above, it will be omitted.

According to the method for reducing hexavalent chromium according to an embodiment of the present invention, at least 10 mol% of hexavalent chromium in the total amount of hexavalent chromium may be reduced to trivalent chromium. More specifically, 20 mol%, 30 mol%, 40 mol%, 50 mol%, 60 mol%, 70 mol%, 80 mol% or 90 mol% or more of hexavalent chromium may be reduced to trivalent chromium. The amount of hexavalent chromium to be reduced may be controlled by the type of organic acid used, reaction conditions, and the like.

In another embodiment of the present invention, preparing a solution containing hexavalent chromium; Adjusting the pH of the solution to 3 or less; It provides a method for reducing hexavalent chromium comprising; and cooling the solution in which the pH is adjusted to 3 or less.

In the above-described method for reducing hexavalent chromium according to an embodiment of the present invention, hexavalent chromium is reduced by using an organic acid. In another embodiment of the present invention, hexavalent chromium is reduced by adjusting the pH of a solution instead of an organic acid. Can be.

At this time, the pH may be adjusted to 3 or less.

The cooling temperature of the step of cooling the solution adjusted to 3 or less pH may be -10 to -196 ℃, the description thereof is described in the method for reducing hexavalent chromium according to an embodiment of the present invention described above Same as bar.

The hexavalent chromium may be reduced to trivalent chromium by the method for reducing hexavalent chromium, and the description thereof is the same as described in the method for reducing hexavalent chromium according to the embodiment of the present invention described above.

At least 10 mol% of hexavalent chromium in the total amount of hexavalent chromium may be reduced to the trivalent chromium, and the description thereof is the same as described in the method for reducing hexavalent chromium according to an embodiment of the present invention described above. .

Hereinafter, specific embodiments of the present invention will be described. However, the embodiments described below are only intended to illustrate or explain the present invention, and thus the present invention should not be limited thereto.

(Input and phase of organic acid phase Reduction of hexavalent chromium according to

Experimental Example  1: 6 μM citric acid

6 µM citric acid in 20 µM aqueous hexavalent chromium solution was injected into the conical tube and mixed.

The mixture was frozen at −10 to −196 ° C. using a cold cooling bath and liquid nitrogen.

The content of hexavalent chromium was calculated by measuring absorbance at 540 nm using a UV / vis-spectrophotometer (spectrophotometer, UV-2401PC Shimadzu or Libra S22) by diphenyl-carbazide (DPC) method.

Experimental Example  2: 60 μM citric acid

In Experimental Example 1, the experiment was performed in the same manner as in Experimental Example 1 except for using citric acid 60μM in place of the citric acid 6μM.

Experimental Example  3: 600 μM citric acid

In Experimental Example 1, an experiment was performed in the same manner as in Experimental Example 1 except for using citric acid 600μM in place of the citric acid 6μM.

Experimental Example  4: 6 μM Oxalic acid

In Experimental Example 1, except that the use of 6μM oxalic acid in place of the citric acid 6μM experiment was carried out in the same manner as in Experiment 1.

Experimental Example  5: 60 μM Oxalic acid

In Experimental Example 1, the experiment was performed in the same manner as in Experimental Example 1 except for using oxalic acid 60μM in place of 6μM citric acid.

Experimental Example  6: 600 μM Oxalic acid

In Experimental Example 1, the experiment was carried out in the same manner as in Experimental Example 1 except for using oxalic acid 600μM in place of the citric acid 6μM.

compare Experimental Example  One

In Experimental Example 1, the experiment was performed in the same manner as in Experimental Example 1, except that the mixture was frozen at -10 to -196 ° C using a low-temperature cooling bath and liquid nitrogen.

compare Experimental Example  2

In Experimental Example 2, the experiment was carried out in the same manner as in Experimental Example 2 except for omitting the process of freezing the mixture to -10 to -196 ℃ using a low-temperature cooling bath and liquid nitrogen.

compare Experimental Example  3

In Experiment 3, the experiment was carried out in the same manner as in Experiment 3, except that the mixture was frozen at a temperature of −10 to −196 ° C. using a low temperature cooling bath and liquid nitrogen.

compare Experimental Example  4

In Experimental Example 4, the experiment was performed in the same manner as in Experimental Example 4, except that the mixture was frozen at -10 to -196 ° C using a low temperature cooling bath and liquid nitrogen.

compare Experimental Example  5

In Experimental Example 5, the experiment was carried out in the same manner as in Experimental Example 5 except for omitting the process of freezing the mixture to -10 to -196 ℃ using a low-temperature cooling bath and liquid nitrogen.

compare Experimental Example  6

In Experimental Example 6, the experiment was performed in the same manner as in Experimental Example 6, except that the mixture was frozen at -10 to -196 ° C using a low temperature cooling bath and liquid nitrogen.

Experiment result

1 is a graph of the results of Experimental Examples 1 to 6.

2 is a graph of the results of Comparative Experimental Examples 1 to 6 above.

As can be seen in Figure 1, it can be seen that the higher the concentration of the organic acid, the faster the reduction rate of hexavalent chromium.

In addition, as can be seen by comparing FIG. 2 with FIG. 1, it can be seen that the reduction reaction of hexavalent chromium did not occur in the comparative experimental example in which the cooling step was not performed at all.

(Reduction Experiment of Hexavalent Chromium According to the Type of Organic Acid)

Experimental Example  7: acetic acid

600 µM of acetic acid was injected into a 20 µM aqueous solution of hexavalent chromium into a conical tube and mixed.

The mixture was frozen at −10 to −196 ° C. using a cold cooling bath and liquid nitrogen.

The content of hexavalent chromium was calculated by measuring absorbance at 540 nm using a UV / vis-spectrophotometer (spectrophotometer, UV-2401PC Shimadzu or Libra S22) by diphenyl-carbazide (DPC) method.

The content of hexavalent chromium was measured based on the state after 3 hours after the reaction.

Experimental Example  8: formic acid

In Experimental Example 7, except that formic acid was used instead of acetic acid, the experiment was carried out in the same manner as in Experimental Example 7.

Experimental Example  9: citric acid

In Experimental Example 7, the experiment was carried out in the same manner as in Experimental Example 7, except that citric acid was used in place of acetic acid.

Experimental Example  10: Oxalic acid

In Experimental Example 7, the experiment was carried out in the same manner as in Experimental Example 7, except that olsalic acid was used in place of acetic acid.

Experimental Example  11: Ethylenediaminetetraacetic acid

In Experimental Example 7, except that ethylenediaminetetraacetic acid was used in place of acetic acid, the experiment was carried out in the same manner as in Experimental Example 7.

Experimental Example  12: Fulvic acid

In Experimental Example 7, the experiment was performed in the same manner as in Experimental Example 7, except that fulvic acid was used in place of acetic acid.

Experimental Example  13: Humic acid

In Experimental Example 7, the experiment was carried out in the same manner as in Experimental Example 7, except that the humic acid was used in place of acetic acid.

Experimental Example  a: pH  change

20 μM hexavalent chromium aqueous solution was injected into the conical tube.

Thereafter, the pH of the aqueous solution was adjusted to 3 or less.

The aqueous solution was frozen at −10 to −196 ° C. using a cold cooling water bath and liquid nitrogen.

The content of hexavalent chromium was calculated by measuring absorbance at 540 nm using a UV / vis-spectrophotometer (spectrophotometer, UV-2401PC Shimadzu or Libra S22) by diphenyl-carbazide (DPC) method.

The content of hexavalent chromium was measured based on the state after 3 hours after the reaction.

compare Experimental Example  7

In Experimental Example 7, the experiment was performed in the same manner as in Experimental Example 7, except that the mixture was frozen at -10 to -196 ° C using a low temperature cooling bath and liquid nitrogen.

compare Experimental Example  8

In Experimental Example 8, the experiment was performed in the same manner as in Experimental Example 8 except that the mixture was frozen at a temperature of -10 to -196 ° C using a low temperature cooling bath and liquid nitrogen.

compare Experimental Example  9

In Experiment 9, the experiment was performed in the same manner as in Experiment 9, except that the process of freezing the mixture at −10 to −196 ° C. using a low temperature cooling bath and liquid nitrogen was omitted.

compare Experimental Example  10

In Experimental Example 10, the experiment was carried out in the same manner as in Experimental Example 10 except that the mixture was frozen at a temperature of -10 to -196 ℃ using a low-temperature cooling bath and liquid nitrogen.

compare Experimental Example  11

In Experiment 11, the experiment was carried out in the same manner as in Experiment 11, except that the mixture was frozen at -10 to -196 ° C using a low temperature cooling bath and liquid nitrogen.

compare Experimental Example  12

In Experimental Example 12, the experiment was carried out in the same manner as in Experimental Example 12 except for omitting the process of freezing the mixture to -10 to -196 ℃ using a low-temperature cooling bath and liquid nitrogen.

compare Experimental Example  13

In Experimental Example 13, the experiment was carried out in the same manner as in Experimental Example 13 except that the mixture was frozen at a temperature of -10 to -196 ℃ using a low-temperature cooling bath and liquid nitrogen.

compare Experimental Example  a

The experiment was carried out in the same manner as in Experimental Example a, except that pH of the aqueous solution was adjusted to 5.6 in Experimental Example a.

Experiment result

3 is a graph showing the results of Experimental Examples 7 to 13, Comparative Experiments 7 to 13, Experimental Example a, and Comparative Experimental Example a.

As shown in Figure 3, regardless of the type of the organic acid it was found that the reduction reaction of hexavalent chromium effectively occurs in the experimental example according to an embodiment of the present invention after the cooling process.

In addition, citric acid and / or oxalic acid among the organic acids, it was confirmed that the ability to reduce the hexavalent chromium is more excellent.

In addition, in the case of Experimental Example a not using an organic acid, it can be seen that the reduction reaction of hexavalent chromium can effectively occur by simply adjusting the pH.

The present invention is not limited to the above embodiments, but may be manufactured in various forms, and a person skilled in the art to which the present invention pertains has another specific form without changing the technical spirit or essential features of the present invention. It will be appreciated that the present invention may be practiced as. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (12)

Preparing a solution containing hexavalent chromium;
Injecting an organic acid into the solution; And
Cooling the solution in which the organic acid is added;
Reduction method of hexavalent chromium comprising.
The method of claim 1,
Cooling temperature of the step of cooling the solution in which the organic acid is added is a method of reducing hexavalent chromium is -10 to -196 ℃.
The method of claim 1,
In the step of adding an organic acid to the solution,
The method for reducing hexavalent chromium, wherein the concentration of the organic acid is 60 mM or less.
The method of claim 1,
The organic acid is formic acid (acetic acid), acetic acid (acetic acid), oxalic acid (oxalic acid), citric acid (citric acid), ethylenediaminetetraacetic acid (EDTA), humic acid (humic acid), fulvic acid ( fulvic acid) or a combination thereof.
The method of claim 1,
The method for reducing hexavalent chromium, wherein the organic acid is a reducing agent for reducing the hexavalent chromium.
The method of claim 1,
The hexavalent chromium is reduced to trivalent chromium by the method of reducing hexavalent chromium.
The method according to claim 6,
10 mol% or more of hexavalent chromium in the total amount of hexavalent chromium is reduced to trivalent chromium.
The method of claim 1,
Wherein the organic acid is oxalic acid (oxalic acid), citric acid (citric acid), ethylenediaminetetraacetic acid (ethylenediaminetetraacetic acid, EDTA) or a combination method of reducing hexavalent chromium.
Preparing a solution containing hexavalent chromium;
Adjusting the pH of the solution to 3 or less; And
Cooling the solution at which the pH is adjusted to 3 or less;
Reduction method of hexavalent chromium comprising.
10. The method of claim 9,
Cooling temperature of the step of cooling the solution adjusted to pH 3 or less is -10 to -196 ℃ reduction method of hexavalent chromium.
10. The method of claim 9,
The hexavalent chromium is reduced to trivalent chromium by the method of reducing hexavalent chromium.
10. The method of claim 9,
Reduction method of hexavalent chromium in which at least 10 mol% of hexavalent chromium in the total amount of hexavalent chromium is reduced to the trivalent chromium.

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