METHOD FOR PREPARING HIGH-VALENCE IRON SALT

Abstract

A method for preparing high-valence iron salt; the present invention relates to a method for preparing a ferrate compound, for solving the technical problems of the complex operating process, the low yield, and the low purity of ferrate products after purification in existing methods for preparing potassium ferrate. The preparation method comprises: 1. weighing solid potassium hydroxide; 2. adding the solid potassium hydroxide to a sodium hypochlorite solution to obtain a hypochlorite solution; 3. adding iron salt to the hypochlorite solution to obtain a potassium ferrate solution; 4. adding the potassium ferrate solution to a cooled potassium hydroxide solution to obtain a solid-liquid mixture; 5. filtering the solid-liquid mixture of step 4; and 6. rinsing the solid-phase substance. The present invention has safe operation, is simple, quick, energy-saving, and easy to control, is suitable for immediate use, and the obtained product can be stored stably; the ferrate yield of the present method is 60-95% and the purity of the produced potassium ferrate solid is over 95%.

Claims

1. A method of preparing high-valent iron salt, characterized in that said method is realized by the following steps of: (1) obtaining and weighing solid potassium hydroxide; (2) adding the potassium hydroxide in solid form from the step (1) to sodium hypochlorite solution, during the process, controlling a temperature of the reaction solution at 0 C.-20 C. to obtain a hypochlorite solution; (3) adding iron salt to the hypochlorite solution obtained in the step (2) so that a molar ratio of hypochlorite to iron salt is 0.5-8:1, then resulting a potassium ferrate solution; (4) Cooling potassium hydroxide solution with a concentration of 10 mol/L 22 mol/L to a cooling temperature of 0 C.-10 C., then adding the potassium ferrate solution in the step (3) to the cooled potassium hydroxide solution and mixing uniformly to obtain a solid-liquid mixture; (5) Filtering the solid-liquid mixture from the step 4 to collect a solid phase substance; (6) Washing the solid phase substance collected from the step (5) to obtain a solid product of high-valent iron salt.

2. The method of preparing high-valent iron salt according to claim 1, characterized in that: in the step (1), the solid potassium hydroxide is in the form of flake particles or powder.

3. The method of preparing high-valent iron salt according to claim 2, characterized in that: in the step (2), an effective concentration of chlorine in the sodium hypochlorite solution is 20150 g/L.

4. The method of preparing high-valent iron salt according to claim 2, characterized in that: in the step (2), a concentration of potassium hydroxide in the hypochlorite solution is 3-15 mol/L.

5. The method of preparing high-valent iron salt according to claim 1, characterized in that: for adding iron salt to the hypochlorite solution in the step (3), a temperature of the reaction solution is controlled at 0 C.60 C. and a reaction time is 10120 min.

6. The method of preparing high-valent iron salt according to claim 1, characterized in that: in the step (3), the molar ratio of hypochlorite to iron salt is 0.55:1.

7. The method of preparing high-valent iron salt according to claim 1, characterized in that: in the step (3), the iron salt is one or a mixture of two or more of the group consisting of: ferric chloride, ferrous chloride, ferric nitrate, ferrous nitrate, ferric sulfate and ferrous sulfate.

8. The method of preparing high-valent iron salt according to claim 1, characterized in that: in the step (4), the potassium hydroxide solution is cooled to a temperature of 2 C.8 C.

9. The method of preparing high-valent iron salt according to claim 1, characterized in that: in the step (5), the solid-liquid mixture is filtered by using a glass fiber membrane.

10. The method of preparing high-valent iron salt according to claim 1, characterized in that: in the step (6), the solid phase substance is washed sequentially with n-hexane, n-pentane, methanol, and ether.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiment 1

[0020] According to this embodiment of the present invention, the preparation method of high-valent iron salt comprises the following steps:

[0021] (1) weighing and obtaining solid potassium hydroxide;

[0022] (2) adding the solid potassium hydroxide in the step (1) to sodium hypochlorite solution to form a reaction solution and control a temperature of the reaction solution at 0 C. to 20 C. to obtain a hypochlorite solution;

[0023] (3) adding iron salt to the hypochlorite solution obtained in the step (2) so that a molar ratio of hypochlorite to iron salt is 0.58:1, then resulting a potassium ferrate solution;

[0024] (4) Cooling potassium hydroxide solution with a concentration of 10 mol/L 22 mol/L to a temperature of 0 C.10 C., adding the potassium ferrate solution in the step (3) to the cooled potassium hydroxide solution and mixing uniformly to obtain a solid-liquid mixture;

[0025] (5) Filtering the solid-liquid mixture from the step 4 to collect a solid phase sub stance;

[0026] (6) Washing the solid phase substance collected from the step (5) to obtain a solid product of high-valent iron salt.

[0027] According to this embodiment, after carrying out the step (3) of adding iron salt to the hypochlorite solution for reaction for 10120 min, a potassium ferrate solution with a yield of 50%95% can be obtained.

[0028] According to this embodiment, the potassium hydroxide solution prepared in the step (4) is a saturated or supersaturated solution. That is, there are some undissolved potassium hydroxide solid particles at the bottom of the container (the mass of the undissolved potassium hydroxide solid particles accounts for 0%50% of the mass of the entire solution system).

Embodiment 2

[0029] This embodiment is different from the embodiment 1 in that the solid potassium hydroxide in the step (1) is in the form of flake particles or powder.

Embodiment 3

[0030] This embodiment is different from the embodiment 1 or 2 in that the effective concentration of chlorine in the sodium hypochlorite solution in the step (2) is 20150 g/L.

Embodiment 4

[0031] This embodiment is different from one of the embodiments 1 to 3 in that the concentration of potassium hydroxide in the hypochlorite solution in the step (2) is 315 mol/L.

Embodiment 5

[0032] This embodiment is different from the embodiment 4 in that the concentration of potassium hydroxide in the hypochlorite solution in the step (2) is 715 mol/L.

Embodiment 6

[0033] This embodiment is different from one of the embodiments 1 to 5 in that: a temperature of the reaction solution is controlled at 0 C.60 C. and a reaction time is 10120 min for the step of adding iron salt to the hypochlorite solution for reaction in the step (3).

Embodiment 7

[0034] This embodiment is different from the embodiment 6 in that: the temperature of the reaction solution is controlled at 5 C.40 C. and a reaction time is 3090 min for the step of adding iron salt to the hypochlorite solution for reaction in the step (3).

Embodiment 8

[0035] This embodiment is different from one of the embodiments 1 to 7 in that: the molar ratio of hypochlorite to iron salt is 0.55:1 in the step (3).

Embodiment 9

[0036] This embodiment is different from the embodiment 8 in that: the molar ratio of hypochlorite to iron salt is 14:1 in the step (3).

Embodiment 10

[0037] This embodiment is different from one of the embodiments 1 to 9 in that: the iron salt in the step (3) is one or a mixture of two or more of the group consisting of: ferric chloride, ferrous chloride, ferric nitrate, ferrous nitrate, ferric sulfate and ferrous sulfate.

Embodiment 11

[0038] This embodiment is different from one of the embodiments 1 to 10 in that: the potassium hydroxide solution is cooled to a temperature of 2 C.8 C. in the step (4).

Embodiment 12

[0039] This embodiment is different from one of the embodiments 1 to 11 in that: a glass fiber membrane is used to filter the solid-liquid mixture.

Embodiment 13

[0040] This embodiment is different from one of the embodiments 1 to 12 in that: the solid phase substance collected in the step (6) is washed sequentially with n-hexane, n-pentane, methanol, and ether.

Exemplary Embodiment 1

[0041] According to this embodiment, the method of preparing high-valent iron salt comprises the following steps:

[0042] (1) obtaining and weighing potassium hydroxide in flake particle form;

[0043] (2) adding the potassium hydroxide in flake particle form in the step (1) to sodium hypochlorite solution to form a reaction solution and control a temperature of the reaction solution at 20 C. to obtain a strong alkaline hypochlorite solution, wherein a potassium hydroxide concentration in the final hypochlorite solution is 4 mol/L;

[0044] (3) adding ferric chloride to the hypochlorite solution obtained from the step (2) so that a molar ratio of hypochlorite to iron salt is 1.5:1, controlling a temperature of the reaction solution at 5 C., allowing reaction for 90 minutes and then a potassium ferrate solution in purple-black color with a yield of 65% is obtained;

[0045] (4) Cooling potassium hydroxide solution with a concentration of 10 mol/L to a temperature of 4 C., under a 4 C. condition (low temperature water bath to control the temperature of the reaction system), adding the potassium ferrate solution from the step (3) to the cooled potassium hydroxide solution and mixing uniformly such that ferrate is precipitated as potassium ferrate crystals to obtain a solid-liquid mixture;

[0046] (5) Filtering the solid-liquid mixture from the step 4 by using a glass fiber membrane with a pore size of 1.2 m to collect a solid phase substance;

[0047] (6) Washing the solid phase substance collected from the step (5) sequentially with n-hexane, n-pentane, methanol, and ether to obtain a solid product of high-valent iron salt.

[0048] According to this embodiment, the purity of the potassium ferrate solid product obtained is 85%.

Exemplary Embodiment 2

[0049] According to this embodiment, the method of preparing high-valent iron salt comprises the following steps:

[0050] (1) obtaining and weighing potassium hydroxide in solid particle form, and crushing by using a pulverizer to form potassium hydroxide in powder form;

[0051] (2) adding the potassium hydroxide in powder form from the step (1) to sodium hypochlorite solution to form a reaction solution and control a temperature of the reaction solution at 10 C. to obtain a hypochlorite solution, wherein a potassium hydroxide concentration in the final hypochlorite solution is 6 mol/L;

[0052] (3) adding ferric chloride to the hypochlorite solution obtained from the step (2) so that a molar ratio of hypochlorite to iron salt is 2:1, controlling a temperature of the reaction solution at 10 C., allowing reaction for 75 minutes and then a potassium ferrate solution in purple-black color with a yield of 75% is obtained;

[0053] (4) Cooling potassium hydroxide solution with a concentration of 20 mol/L to a temperature of 5 C., under a 0 C. condition, adding the potassium ferrate solution from the step (3) to the cooled potassium hydroxide solution and mixing uniformly such that ferrate is precipitated as potassium ferrate crystals to obtain a solid-liquid mixture;

[0054] (5) Filtering the solid-liquid mixture from the step 4 by using a glass fiber membrane with a pore size of 1.2 m to collect a solid phase substance;

[0055] (6) Washing the solid phase substance collected from the step (5) sequentially with n-hexane, n-pentane, methanol, and ether to obtain a solid product of high-valent iron salt.

[0056] According to this embodiment, the purity of the potassium ferrate solid product obtained is 88%.

Exemplary Embodiment 3

[0057] According to this embodiment, the method of preparing high-valent iron salt comprises the following steps:

[0058] (1) obtaining and weighing potassium hydroxide in solid particle form, and crushing by using a pulverizer to form potassium hydroxide in powder form;

[0059] (2) adding the potassium hydroxide in powder form from the step (1) to sodium hypochlorite solution to form a reaction solution and control a temperature of the reaction solution at 5 C. to obtain a hypochlorite solution, wherein a potassium hydroxide concentration in the final hypochlorite solution is 7 mol/L;

[0060] (3) adding ferric chloride to the hypochlorite solution obtained from the step (2) so that a molar ratio of hypochlorite to iron salt is 3:1, controlling a temperature of the reaction solution at 25 C., allowing reaction for 45 minutes and then a potassium ferrate solution in purple-black color with a yield of 85% is obtained;

[0061] (4) Cooling potassium hydroxide solution with a concentration of 15 mol/L to a temperature of 6 C., under a 2 C. condition, adding the potassium ferrate solution from the step (3) to the cooled potassium hydroxide solution and mixing uniformly such that ferrate is precipitated as potassium ferrate crystals to obtain a solid-liquid mixture;

[0062] (5) Filtering the solid-liquid mixture from the step 4 by using a glass fiber membrane with a pore size of 1.2 m to collect a solid phase substance;

[0063] (6) Washing the solid phase substance collected from the step (5) sequentially with n-hexane, n-pentane, methanol, and ether to obtain a solid product of high-valent iron salt.

[0064] According to this embodiment, the purity of the potassium ferrate solid product obtained is 90%.

Exemplary Embodiment 4

[0065] According to this embodiment, the method of preparing high-valent iron salt comprises the following steps:

[0066] (1) obtaining and weighing potassium hydroxide in solid particle form, and crushing by using a pulverizer to form potassium hydroxide in powder form;

[0067] (2) adding the potassium hydroxide in powder form from the step (1) to sodium hypochlorite solution to form a reaction solution and control a temperature of the reaction solution at 5 C. to obtain a hypochlorite solution, wherein a potassium hydroxide concentration in the final hypochlorite solution is 8 mol/L;

[0068] (3) adding ferric chloride to the hypochlorite solution obtained from the step (2) so that a molar ratio of hypochlorite to iron salt is 4:1, controlling a temperature of the reaction solution at 35 C., allowing reaction for 30 minutes and then a potassium ferrate solution in purple-black color with a yield of 92% is obtained;

[0069] (4) Cooling potassium hydroxide solution with a concentration of 18 mol/L to a temperature of 8 C., under a 4 C. temperature condition, adding the potassium ferrate solution from the step (3) to the cooled potassium hydroxide solution and mixing uniformly such that ferrate is precipitated as potassium ferrate crystals to obtain a solid-liquid mixture;

[0070] (5) Filtering the solid-liquid mixture from the step 4 by using a glass fiber membrane with a pore size of 1.2 m to collect a solid phase substance;

[0071] (6) Washing the solid phase substance collected from the step (5) sequentially with n-hexane, n-pentane, methanol, and ether to obtain a solid product of high-valent iron salt.

[0072] According to this embodiment, the purity of the potassium ferrate solid product obtained is 93%.

Exemplary embodiment 5

[0073] According to this embodiment, the method of preparing high-valent iron salt comprises the following steps:

[0074] (1) obtaining and weighing potassium hydroxide in solid particle form, and crushing by using a pulverizer to form potassium hydroxide in powder form;

[0075] (2) adding the potassium hydroxide in powder form from the step (1) to sodium hypochlorite solution to form a reaction solution and control a temperature of the reaction solution at 0 C. to obtain a hypochlorite solution, wherein a potassium hydroxide concentration in the final hypochlorite solution is 9 mol/L;

[0076] (3) adding ferric chloride to the hypochlorite solution obtained from the step (2) so that a molar ratio of hypochlorite to iron salt is 4:1, controlling a temperature of the reaction solution at 35 C., allowing reaction for 30 minutes and then a potassium ferrate solution in purple-black color with a yield of 95% is obtained;

[0077] (4) Cooling potassium hydroxide solution with a concentration of 22 mol/L to a temperature of 4 C., under a 4 C. temperature condition, adding the potassium ferrate solution from the step (3) to the cooled potassium hydroxide solution and mixing uniformly such that ferrate is precipitated as potassium ferrate crystals to obtain a solid-liquid mixture;

[0078] (5) Filtering the solid-liquid mixture from the step 4 by using a glass fiber membrane with a pore size of 1.2 m to collect a solid phase substance;

[0079] (6) Washing the solid phase substance collected from the step (5) sequentially with n-hexane, n-pentane, methanol, and ether to obtain a solid product of high-valent iron salt.

[0080] According to this embodiment, the purity of the potassium ferrate solid product obtained is 95%.

Exemplary Embodiment 6

[0081] According to this embodiment, the method of preparing high-valent iron salt comprises the following steps:

[0082] (1) obtaining and weighing potassium hydroxide in solid particle form, and crushing by using a pulverizer to form potassium hydroxide in powder form;

[0083] (2) adding the potassium hydroxide in powder form from the step (1) to sodium hypochlorite solution to form a reaction solution and control a temperature of the reaction solution at 0 C. to obtain a hypochlorite solution, wherein a potassium hydroxide concentration in the final hypochlorite solution is 9 mol/L;

[0084] (3) adding ferric chloride to the hypochlorite solution obtained from the step (2) so that a molar ratio of hypochlorite to iron salt is 4:1, controlling a temperature of the reaction solution at 35 C., allowing reaction for 30 minutes and then a potassium ferrate solution in purple-black color with a yield of 95% is obtained;

[0085] (4) dissolving potassium hydroxide in solid particle form at a room temperature (10 C.-35 C.) to prepare a saturated potassium hydroxide solution, some of the potassium hydroxide in solid particle form are undissolved at a bottom of a container (a mass of the undissolved potassium hydroxide in solid particle form accounts for 50% of the entire solution system, cooling the fully saturated potassium hydroxide solution to a temperature of 4 C., under a 4 C. temperature condition, adding the potassium ferrate solution from the step (3) to the cooled potassium hydroxide solution and mixing uniformly such that ferrate is precipitated as potassium ferrate crystals to obtain a solid-liquid mixture;

[0086] (5) Filtering the solid-liquid mixture from the step 4 by using a glass fiber membrane with a pore size of 1.2 m to collect a solid phase substance;

[0087] (6) Washing the solid phase substance collected from the step (5) sequentially with n-hexane, n-pentane, methanol, and ether to obtain a solid product of high-valent iron salt.

[0088] According to this embodiment, the purity of the potassium ferrate solid product obtained is 95%.