Cyclic regeneration method of waste activated carbon and preparation method of dihydric phosphate

Abstract

The invention discloses a cyclic regeneration method of waste activated carbon and a preparation method of dihydric phosphate, relates to the technical field of activated carbon regeneration, and aims to solve the technical problems of high energy consumption and poor regeneration effect of an existing activated carbon regeneration technology. The cyclic regeneration method of the waste activated carbon comprises the following steps: obtaining the waste activated carbon, adding the activated carbon into water, stirring and pulping, and filtering to obtain washed carbon; adding an alkali solution into the washed carbon, carrying out ultrasonic oscillation, and filtering to obtain alkali washed carbon and an alkali washing solution; adding the alkali-washed carbon into an aqueous solution containing a surfactant, stirring and pulping, and filtering to obtain regenerated activated carbon; the preparation method of the dihydric phosphate comprises the following steps: adding phosphoric acid into an alkali wash solution for reaction, concentrating the reaction solution in a stirring state until crystals are separated out, and filtering to obtain a dihydric phosphate product. The technical scheme is used for regenerating the waste activated carbon.

Description

Technical Field

[0001] The invention relates to the technical field of activated carbon regeneration, and in particular to a method for recycling waste activated carbon and preparing dihydrogen phosphate. Background Art

[0002] Activated carbon is a material with special adsorption properties, which is widely used in environmental protection, chemical industry, pharmaceutical industry and other fields. During use, due to adsorption saturation or other reasons, activated carbon will lose its adsorption properties and become waste. The traditional treatment method is to incinerate or landfill the waste activated carbon, which not only wastes resources, but also pollutes the environment.

[0003] In order to solve this problem, people have proposed a method for regenerating activated carbon. At present, common activated carbon regeneration methods include physical method, chemical method and biological method. Among them, the physical method mainly desorbs the adsorbate by physical means such as high temperature or low temperature, but this method has problems such as high energy consumption, complex equipment and poor regeneration effect; the chemical method mainly decomposes the adsorbate by chemical reaction, but this method has problems such as environmental pollution and consumption of chemical agents; the biological method mainly decomposes the adsorbate by the action of microorganisms, but this method has problems such as complex operation and long regeneration cycle. Therefore, a new activated carbon regeneration method is urgently needed to solve the above technical problems. Summary of the invention

[0004] In order to solve the technical problems of high energy consumption, poor regeneration effect and complicated operation of the existing activated carbon regeneration technology, the present invention provides a method for recycling and regenerating waste activated carbon and preparing dihydrogen phosphate. In view of this, the present invention is implemented through the following scheme.

[0005] In a first aspect, the present invention provides a method for recycling waste activated carbon, comprising:

[0006] Obtaining waste activated carbon, wherein the waste activated carbon is activated carbon used for decolorization in the process of preparing inositol and phosphate by hydrolysis of phytate;

[0007] Add the waste activated carbon into water, stir and slurry for 10 to 40 minutes, and obtain washed carbon after filtering;

[0008] Adding an alkaline solution to the water-washed carbon, and subjecting the carbon to ultrasonic vibration for 0.5 to 1 h at a temperature of 50 to 80° C. and a vibration frequency of 20 to 50 KHz, and filtering to obtain an alkaline-washed carbon and an alkaline washing liquid; wherein the mass concentration of the alkaline solution is 8 to 13 wt %, and the mass ratio of the water-washed carbon to the alkaline solution is 1:(1 to 3);

[0009] The alkali-washed carbon is added to an aqueous solution containing a surfactant, stirred and slurried for 10 to 50 minutes, and regenerated activated carbon is obtained after filtering; wherein the mass ratio of the alkali-washed carbon, the surfactant and the water is (80 to 100):0.1:(100 to 200).

[0010] Compared with the prior art, in the recycling and regeneration method of waste activated carbon of the present invention, the waste activated carbon is activated carbon used for decolorization in the process of preparing inositol and phosphate by hydrolysis of phytate. In the decolorization process, pigments, oils, inositol or phosphates are adsorbed on the waste activated carbon. In the process of adding the activated carbon to pure water and stirring and beating, the soluble phosphates remaining on the surface of the activated carbon are dissolved in water and removed by filtration to obtain the water-washed carbon; by adding an alkaline solution to the water-washed carbon and controlling the temperature at the same time, during the ultrasonic oscillation process, the pigments and other impurities adsorbed by the water-washed carbon can be completely dissolved in the alkaline solution, the water-washed carbon can be analyzed, and the alkali-washed carbon can be obtained by filtration. At this time, impurities such as oils and fats may also be adsorbed on the surface of the alkali-washed carbon, and a large amount of alkaline solution remains. By adding the alkali-washed carbon to an aqueous surfactant solution and stirring and beating, the alkali solution and the surfactant work together to improve the removal rate of impurities such as oils and fats adsorbed on the surface of the alkali-washed carbon. After filtration, the filter cake is dried to obtain the regenerated activated carbon. The above technical solution of the present invention solves the technical problems of high energy consumption, poor regeneration effect and complicated operation of the existing activated carbon regeneration technology.

[0011] Furthermore, in the recycling and regeneration method of waste activated carbon of the present invention, the alkaline solution also includes a short-chain alcohol, wherein the mass ratio of the short-chain alcohol, the alkali and the solvent water added is (0.5-1):

[0012] (7.2~14.3):(90~110); the mass ratio of the water-washed carbon to the alkaline solution containing short-chain alcohol is 1:(1~3).

[0013] Furthermore, in the recycling and regeneration method of waste activated carbon of the present invention, the short-chain alcohol includes any one or more of methanol, ethanol, and isopropanol; the alkali includes any one or more of NaOH, KOH, and ammonia water.

[0014] Furthermore, in the recycling and regeneration method of waste activated carbon of the present invention, the surfactant includes one or more of sodium fatty alcohol hydroxyethyl sulfonate, dodecyl phosphate, ammonium dodecyl sulfate, sodium dodecyl sulfate, dodecyl phosphate triethanolamine, hexadecyltrimethylammonium chloride or amide polyoxyethylene ether magnesium sulfate.

[0015] Furthermore, in the recycling and regeneration method of waste activated carbon of the present invention, in the carbon washing step, the mass ratio of the activated carbon to the water is 1:(1-2); and / or,

[0016] The mass ratio of the alkali-washed carbon to the aqueous solution containing a surfactant is 1:(1-2).

[0017] Furthermore, in the recycling and regeneration method of waste activated carbon of the present invention, after obtaining the alkali-washed carbon, before adding the alkali-washed carbon to the surfactant aqueous solution for stirring and slurrying, the method further comprises:

[0018] Add the alkali-washed carbon into the acid solution, stir and slurry for 0.5 to 1 hour, and obtain the acid-washed carbon after filtering;

[0019] The mass ratio of the alkali-washed carbon to the acid solution is 1:(1-3), the concentration of the acid solution is 1-3wt%, the temperature of the acid solution is 25-55°C, and the stirring rate is 20-100rpm.

[0020] Furthermore, in the recycling regeneration method of waste activated carbon of the present invention, the acid solution includes 1-3wt% phosphoric acid, 1-3wt% hydrochloric acid, 1-3wt% nitric acid or 1-3wt% sulfuric acid.

[0021] In a second aspect, the present invention provides a regenerated activated carbon obtained by utilizing the above-mentioned recycling regeneration method of waste activated carbon, wherein the iodine adsorption value of the regenerated activated carbon is 900 to 1400 (mg / g).

[0022] Compared with the prior art, the beneficial effects of the regenerated activated carbon described in the present invention are the same as the beneficial effects of the recycling regeneration method of waste activated carbon described in the above technical solution, and will not be repeated here.

[0023] In a third aspect, the present invention provides a method for preparing dihydrogen phosphate, wherein phosphoric acid is added to an alkaline washing liquid for reaction, the amount of phosphoric acid added is to adjust the pH value of the reaction liquid to 3.2 to 3.8, and the reaction is carried out at the pH value for 0.5 to 1 hour; wherein the alkaline washing liquid is the alkaline washing liquid produced in the above-mentioned recycling regeneration method of waste activated carbon, and the concentration of the phosphoric acid is 75 to 85 wt%;

[0024] The reaction solution is concentrated under stirring until crystals are precipitated, and then filtered to obtain a dihydrogen phosphate product; wherein the temperature during the concentration is 70-100° C. and the stirring rate is 20-100 rpm.

[0025] Compared with the prior art, the beneficial effects of the method for preparing dihydrogen phosphate described in the present invention are the same as the beneficial effects of the method for recycling and regenerating waste activated carbon described in the above technical scheme, and will not be repeated here.

[0026] In a fourth aspect, the present invention provides a dihydrogen phosphate product prepared by the above-mentioned dihydrogen phosphate preparation method, wherein the dihydrogen phosphate content in the dihydrogen phosphate product is 85-95wt%, and the remainder is impurities.

[0027] Compared with the prior art, the beneficial effects of the dihydrogen phosphate product described in the present invention are the same as the beneficial effects of the recycling regeneration method of waste activated carbon described in the above technical solution, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0029] Figure 1 A schematic flow chart of the recycling regeneration method of waste activated carbon provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] At present, common activated carbon regeneration methods include physical method, chemical method and biological method. Among them, the physical method mainly uses physical means such as high temperature or low temperature to desorb the adsorbent, but this method has problems such as high energy consumption, complex equipment and poor regeneration effect; the chemical method mainly decomposes the adsorbent through chemical reactions, but this method has problems such as environmental pollution and consumption of chemical agents; the biological method mainly decomposes the adsorbent through the action of microorganisms, but this method has problems such as complex operation and long regeneration cycle.

[0032] In order to solve the above technical problems, in a first aspect, the present invention provides a recycling method for waste activated carbon, comprising:

[0033] Obtaining waste activated carbon, wherein the waste activated carbon is activated carbon used for decolorization in the process of preparing inositol and phosphate by hydrolysis of phytate;

[0034] Add the waste activated carbon into water, stir and slurry for 10 to 40 minutes, and obtain washed carbon after filtering;

[0035] Adding an alkaline solution to the water-washed carbon, and subjecting the carbon to ultrasonic vibration for 0.5 to 1 h at a temperature of 50 to 80° C. and a vibration frequency of 20 to 50 KHz, and filtering to obtain an alkaline-washed carbon and an alkaline washing liquid; wherein the mass concentration of the alkaline solution is 8 to 13 wt %, and the mass ratio of the water-washed carbon to the alkaline solution is 1:(1 to 3);

[0036] The alkali-washed carbon is added to an aqueous solution containing a surfactant, stirred and slurried for 10 to 50 minutes, and regenerated activated carbon is obtained after filtering; wherein the mass ratio of the alkali-washed carbon, the surfactant and the water is (80 to 100):0.1:(100 to 200).

[0037] By adopting the above technical scheme, in the recycling and regeneration method of waste activated carbon of the present invention, the waste activated carbon is the activated carbon used for decolorization in the process of preparing inositol and phosphate by hydrolysis of phytate. In the decolorization process, pigments, oils, inositol or phosphates are adsorbed on the waste activated carbon. In the process of adding the activated carbon into pure water and stirring and beating, the soluble phosphates remaining on the surface of the activated carbon are dissolved in the water and removed by filtration to obtain the water-washed carbon; by adding an alkaline solution to the water-washed carbon and controlling the temperature at the same time, during the ultrasonic oscillation process, the pigments and other impurities adsorbed by the water-washed carbon can be completely dissolved in the alkaline solution, the water-washed carbon can be analyzed, and the alkali-washed carbon can be obtained by filtration. At this time, impurities such as oils and fats may also be adsorbed on the surface of the alkali-washed carbon, and a large amount of alkaline solution remains. By adding the alkali-washed carbon into a surfactant aqueous solution and stirring and beating, the alkaline solution and the surfactant work together to improve the removal rate of impurities such as oils and fats adsorbed on the surface of the alkali-washed carbon. After filtration, the filter cake is dried to obtain the regenerated activated carbon.

[0038] As a possible implementation manner, the alkaline solution of the present invention also includes a short-chain alcohol, wherein the mass ratio of the short-chain alcohol, the alkali and the added solvent water is (0.5-1):(7.2-14.3):(90-110); the mass ratio of the water-washed carbon to the alkaline solution containing the short-chain alcohol is 1:(1-3).

[0039] By adopting the above technical scheme, adding a short-chain alcohol to the alkaline solution, and controlling the amount of short-chain alcohol added in the alkaline solution, and the mass ratio of the water-washed carbon to the alkaline solution containing the short-chain alcohol, the synergistic effect of the alkaline solution and the short-chain alcohol can effectively improve the efficiency of the analysis of impurities contained in the water-washed carbon, thereby obtaining the alkaline-washed carbon after removing impurities such as pigments. For example, the mass ratio of the short-chain alcohol, the alkali and the solvent water added can be (0.5-1): (7.2-14.3): (90-110). However, it has been verified by experiments that when the pH value of the alkaline solution containing the alkaline-washed carbon reaches 12-13.5, when the amount of short-chain alcohol added in the alkaline solution containing the short-chain alcohol is 0.45-0.65wt%, the adsorption capacity of the regenerated activated carbon can reach the best, and the adsorption iodine value can reach 1200-1300 (mg / g).

[0040] It should be understood that in order to improve the analysis efficiency of the water-washed carbon, the present invention also needs to control the types of the short-chain alcohol and the base. For example, the short-chain alcohol includes any one or more of methanol, ethanol, and isopropanol; the base includes any one or more of NaOH, KOH, and ammonia water.

[0041] It should also be understood that in order to improve the removal efficiency of impurities such as grease adsorbed on the surface of the alkali-washed carbon and the removal efficiency of the residual alkali solution, it is also necessary to control the type of the surfactant. For example, the surfactant includes one or more of sodium fatty alcohol hydroxyethyl sulfonate, dodecyl phosphate, ammonium dodecyl sulfate, sodium dodecyl sulfate, dodecyl phosphite triethanolamine, hexadecyl trimethyl ammonium chloride or amido polyoxyethylene ether magnesium sulfate. For another example, the surfactant can be dodecyl phosphate, sodium dodecyl sulfate or hexadecyl trimethyl ammonium chloride.

[0042] It should also be understood that in order to improve the regeneration efficiency of the waste activated carbon, the present invention also needs to control the mass ratio of the activated carbon to the water, and the mass ratio of the alkali-washed carbon to the surfactant aqueous solution. For example, in the water-washed carbon step, the mass ratio of the activated carbon to the water is 1:(1-2); the mass ratio of the alkali-washed carbon to the surfactant aqueous solution is 1:(1-2). For another example, the mass ratio of the activated carbon to the water can be 1:1, 1:1.5 or 1:2, and the mass ratio of the alkali-washed carbon to the surfactant aqueous solution can be 1:1, 1:1.5 or 1:2.

[0043] As a possible implementation mode, in the recycling and regeneration method of waste activated carbon of the present invention, after obtaining the alkali-washed carbon, before adding the alkali-washed carbon to the surfactant aqueous solution and stirring and slurrying, the method further comprises:

[0044] Add the alkali-washed carbon into the acid solution, stir and slurry for 0.5 to 1 hour, and obtain the acid-washed carbon after filtering;

[0045] The mass ratio of the alkali-washed carbon to the acid solution is 1:(1-3), the concentration of the acid solution is 1-3wt%, the temperature of the acid solution is 25-55°C, and the stirring rate is 20-100rpm.

[0046] By adopting the above technical scheme, calcium and magnesium salts still remain on the surface of the alkali-washed carbon. After the alkali-washed carbon is first added to the acid solution and stirred for 0.5 to 1h, the calcium and magnesium salts remaining on the surface of the alkali-washed carbon are dissolved in the acid solution, and the acid-washed carbon is obtained after filtration. The mass ratio of the alkali-washed carbon to the acid solution, the concentration of the acid solution, and the temperature and stirring rate of the acid solution can all improve the acid washing efficiency of the calcium and magnesium salts on the surface of the alkali-washed carbon, and the acid-washed carbon after removing the calcium and magnesium salts is obtained. It should be understood that after obtaining the acid-washed carbon, the acid-washed carbon can be directly added to the surfactant aqueous solution for stirring and beating, and the regenerated activated carbon can be obtained after filtration. However, the inventors found that when the acid-washed carbon is added to the aqueous solution containing the surfactant, the adsorption performance of the regenerated activated carbon can be greatly improved by adjusting the pH value of the solution to alkaline. In particular, when the pH value is 8 to 9, the adsorption performance of the regenerated activated carbon can reach the best, and the adsorption iodine value is 1300 to 1400 (mg / g). For example, the mass ratio of the alkali-washed charcoal to the acid solution can be 1:1, 1:2 or 1:3, the concentration of the acid solution can be 1wt%, 2wt% or 3wt%, the temperature of the acid solution can be 25°C, 35°C or 55°C, and the stirring rate can be 20rpm, 50rpm or 70rpm.

[0047] It should also be understood that in order to further improve the pickling efficiency of calcium and magnesium salts on the surface of the alkali-washed carbon, it is also necessary to control the type of the acid solution. For example, the acid solution includes 1 to 3 wt% phosphoric acid, 1 to 3 wt% hydrochloric acid, 1 to 3 wt% nitric acid or 1 to 3 wt% sulfuric acid.

[0048] In a second aspect, the present invention provides a regenerated activated carbon obtained by utilizing the above-mentioned recycling regeneration method of waste activated carbon, wherein the iodine adsorption value of the regenerated activated carbon is 900 to 1400 (mg / g).

[0049] Compared with the prior art, the beneficial effects of the regenerated activated carbon provided by the present invention are the same as the beneficial effects of the recycling regeneration method of waste activated carbon described in the above technical solution, and will not be elaborated here.

[0050] In a third aspect, the present invention provides a method for preparing dihydrogen phosphate, wherein phosphoric acid is added to an alkaline washing liquid for reaction, the amount of phosphoric acid added is to adjust the pH value of the reaction liquid to 3.2 to 3.8, and the reaction is carried out at the pH value for 0.5 to 1 hour; wherein the alkaline washing liquid is the alkaline washing liquid produced in the above-mentioned recycling regeneration method of waste activated carbon, and the concentration of the phosphoric acid is 75 to 85 wt%;

[0051] The reaction solution is concentrated under stirring until crystals are precipitated, and then filtered to obtain a dihydrogen phosphate product; wherein the temperature during the concentration is 70-100° C. and the stirring rate is 20-100 rpm.

[0052] Compared with the prior art, the beneficial effects of the preparation method of dihydrogen phosphate of the present invention are the same as the beneficial effects of the recycling and regeneration method of waste activated carbon described in the above technical solution. At the same time, in the process of adding phosphoric acid to the alkaline washing solution to adjust the pH value of the reaction solution to 3.2-3.8, the alkali in the alkaline washing solution reacts with phosphoric acid to obtain dihydrogen phosphate, so that the alkaline washing solution generated in the recycling and regeneration process of the waste activated carbon is recycled, and the alkaline washing solution is concentrated to crystallize and precipitate, and the dihydrogen phosphate product can be obtained after filtration. Controlling the concentration of the phosphoric acid, the temperature during concentration and the stirring rate can increase the preparation amount of the dihydrogen phosphate product. For example, the concentration of the phosphoric acid can be 75wt%, 80wt% or 85wt%, the temperature during concentration can be 70℃, 85℃ or 100℃, and the stirring rate can be 20rpm, 50rpm or 100rpm.

[0053] In a fourth aspect, the present invention provides a dihydrogen phosphate product prepared by the above-mentioned dihydrogen phosphate preparation method, wherein the dihydrogen phosphate content in the dihydrogen phosphate product is 85-95wt%, and the remainder is impurities.

[0054] Compared with the prior art, the beneficial effects of the dihydrogen phosphate product described in the present invention are the same as the beneficial effects of the method for preparing dihydrogen phosphate described in the above technical scheme, which will not be repeated here.

[0055] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with specific embodiments, but the content of the present invention is not limited to the following embodiments.

[0056] Unless otherwise specified, the raw materials used in the following examples are commercially available.

[0057] Example 1

[0058] This embodiment provides a method for recycling waste activated carbon, comprising the following steps:

[0059] S100, obtaining 1000 g of waste activated carbon, wherein the waste activated carbon is activated carbon used for decolorization in the process of preparing inositol and phosphate by hydrolysis of phytate;

[0060] S200, adding the waste activated carbon to water at a mass ratio of 1:1, stirring and slurrying for 10 minutes, and filtering to obtain washed carbon;

[0061] S300, adding 8 wt % NaOH solution to the water-washed carbon in a mass ratio of 1:1, and ultrasonically oscillating the water-washed carbon for 0.5 h at a temperature of 50° C. and a vibration frequency of 20 kHz using an ultrasonic oscillator, and filtering to obtain alkali-washed carbon and alkali-washing liquid;

[0062] S400, adding the alkali-washed carbon to an aqueous solution containing a surfactant, stirring and slurrying for 10 minutes, and filtering to obtain regenerated activated carbon; wherein the surfactant is a mixture of equal masses of sodium fatty alcohol hydroxyethyl sulfonate, dodecyl phosphate and ammonium dodecyl sulfate, and the mass ratio of the alkali-washed carbon, the surfactant and the water is 80:0.1:100.

[0063] The iodine adsorption value of the regenerated activated carbon obtained in this example was measured, and the iodine adsorption value of the regenerated activated carbon was 963 (mg / g).

[0064] Example 2

[0065] This embodiment provides a method for recycling and regenerating waste activated carbon and co-producing potassium dihydrogen phosphate, comprising the following steps:

[0066] S100, obtaining 1000 g of waste activated carbon, wherein the waste activated carbon is activated carbon used for decolorization in the process of preparing inositol and phosphate by hydrolysis of phytate;

[0067] S200, adding the waste activated carbon to pure water at a mass ratio of 1:2, stirring and slurrying for 25 minutes, and filtering to obtain washed carbon;

[0068] S300, according to the mass ratio of the water-washed carbon to the KOH solution being 1:2, 13wt% KOH solution is added to the water-washed carbon, and ultrasonically oscillates the carbon for 1h at a temperature of 60°C and a vibration frequency of 30KHz, and then filtration is performed to obtain alkali-washed carbon and alkali-washing liquid; wherein the pH value of the KOH solution containing the water-washed carbon during the ultrasonic oscillation process is 13.5, and 80vt% ethanol is added to the KOH solution, and the mass ratio of the added amounts of ethanol, KOH and solvent water in the KOH solution is 1:14.3:110;

[0069] S400, according to the mass ratio of the alkali-washed carbon to the acid solution being 1:1, the alkali-washed carbon is added to the acid solution and stirred and slurried for 0.5 h, and the acid-washed carbon is obtained after filtering; wherein the acid solution is 1.5 wt % phosphoric acid, the temperature of the acid solution is 25° C., and the stirring rate is 100 rpm;

[0070] S500, adding 5wt% KOH solution to the aqueous solution containing surfactant to adjust the pH value to 8, and adding the acid-washed carbon in step S400 to the aqueous solution containing surfactant, stirring and beating for 10 minutes, and filtering to obtain regenerated activated carbon; wherein the surfactant is a mixture of equal weights of sodium fatty alcohol isethionate, dodecyl phosphate and amide polyoxyethylene ether magnesium sulfate, and the mass ratio of the acid-washed carbon, surfactant and water is 100:0.1:200;

[0071] S600, adding 75wt% of phosphoric acid to the alkaline washing solution obtained in step S300 to adjust the pH value of the alkaline washing solution to 3.8, and reacting for 1h, so that the KOH in the alkaline washing solution reacts with the phosphoric acid to generate potassium dihydrogen phosphate; then concentrating the alkaline washing solution at a temperature of 70°C and a stirring rate of 100rpm until all the potassium dihydrogen phosphate crystals are precipitated, and filtering to obtain a potassium dihydrogen phosphate product.

[0072] The iodine adsorption value of the regenerated activated carbon obtained in this example was measured, and the potassium dihydrogen phosphate product was subjected to a purity analysis. The iodine adsorption value of the regenerated activated carbon was 1325 (mg / g), the potassium dihydrogen phosphate content in the potassium dihydrogen phosphate product was 92wt%, and the rest was impurities.

[0073] Example 3

[0074] This embodiment provides a method for recycling and regenerating waste activated carbon and co-producing potassium dihydrogen phosphate, comprising the following steps:

[0075] S100, obtaining 1000 g of waste activated carbon, wherein the waste activated carbon is activated carbon used for decolorization in the process of preparing inositol and phosphate by hydrolysis of phytate;

[0076] S200, adding the waste activated carbon to pure water at a mass ratio of 1:2, stirring and slurrying for 40 minutes, and filtering to obtain washed carbon;

[0077] S300, according to the mass ratio of the water-washed carbon to the KOH solution being 1:3, 11wt% KOH solution is added to the water-washed carbon, and ultrasonically oscillates the carbon for 1h at a temperature of 80°C and a vibration frequency of 50KHz, and then filtration is performed to obtain alkali-washed carbon and alkali-washing liquid; wherein the pH value of the KOH solution containing the water-washed carbon during the ultrasonic oscillation process is 12, and 80vt% isopropanol is added to the KOH solution, and the mass ratio of the amount of isopropanol, KOH and solvent water added in the KOH solution is 0.45:11:100;

[0078] S400, adding the alkali-washed carbon to the acid solution in a mass ratio of 1:2, stirring and slurrying for 1 hour, and filtering to obtain the acid-washed carbon; wherein the acid solution is 3 wt % hydrochloric acid, the temperature of the acid solution is 55° C., and the stirring rate is 20 rpm;

[0079] S500, adding 5wt% KOH solution to the aqueous solution containing surfactant to adjust the pH value to 8.5, and adding the acid-washed carbon in step S400 to the aqueous solution containing surfactant, stirring and beating for 50 minutes, and filtering to obtain regenerated activated carbon; wherein the surfactant is a mixture of equal weights of sodium fatty alcohol isethionate, dodecyl phosphate and amide polyoxyethylene ether magnesium sulfate, and the mass ratio of the acid-washed carbon, surfactant and water is 90:0.1:150;

[0080] S600, adding 85wt% of phosphoric acid to the alkaline washing solution obtained in step S300 to adjust the pH value of the alkaline washing solution to 3.2, and reacting for 0.5h, so that KOH in the alkaline washing solution reacts with the phosphoric acid to generate potassium dihydrogen phosphate; then concentrating the alkaline washing solution at a temperature of 100°C and a stirring rate of 20rpm until all potassium dihydrogen phosphate crystals are precipitated, and filtering to obtain a potassium dihydrogen phosphate product.

[0081] The iodine adsorption value of the regenerated activated carbon obtained in this example was measured, and the purity of the potassium dihydrogen phosphate product was analyzed. The iodine adsorption value of the regenerated activated carbon was 1352 (mg / g), the potassium dihydrogen phosphate content in the potassium dihydrogen phosphate product was 93wt%, and the rest was impurities.

[0082] Example 4

[0083] This embodiment provides a method for recycling and regenerating waste activated carbon and co-producing potassium dihydrogen phosphate, comprising the following steps:

[0084] S100, obtaining 1000 g of waste activated carbon, wherein the waste activated carbon is activated carbon used for decolorization in the process of preparing inositol and phosphate by hydrolysis of phytate;

[0085] S200, adding the waste activated carbon to pure water at a mass ratio of 1:2, stirring and slurrying for 40 minutes, and filtering to obtain washed carbon;

[0086] S300, according to the mass ratio of the water-washed carbon to the KOH solution being 1:3, 12wt% KOH solution is added to the water-washed carbon, and ultrasonically oscillates the carbon for 1h at a temperature of 70°C and a vibration frequency of 45KHz, and then filtration is performed to obtain alkali-washed carbon and alkali-washing liquid; wherein the pH value of the KOH solution containing the water-washed carbon during the ultrasonic oscillation process is 13, and 80vt% methanol is added to the KOH solution, and the mass ratio of the added amounts of methanol, KOH and solvent water in the KOH solution is 0.65:12:100;

[0087] S400, adding the alkali-washed carbon to the acid solution in a mass ratio of 1:3, stirring and slurrying for 0.8 h, and filtering to obtain the acid-washed carbon; wherein the acid solution is 3 wt % nitric acid, the temperature of the acid solution is 40° C., and the stirring rate is 50 rpm;

[0088] S500, adding 5wt% KOH solution to the aqueous solution containing surfactant to adjust the pH value to 9, and adding the acid-washed carbon in step S400 to the aqueous solution containing surfactant, stirring and slurrying for 45 minutes, and filtering to obtain regenerated activated carbon; wherein the surfactant is a mixture of dodecyl phosphate and hexadecyltrimethylammonium chloride in equal weights, and the mass ratio of the acid-washed carbon, the surfactant and the water is 85:0.1:120;

[0089] S600, adding 80wt% of phosphoric acid to the alkaline washing solution obtained in step S300 to adjust the pH value of the alkaline washing solution to 3.5, and reacting for 1h, so that the KOH in the alkaline washing solution reacts with the phosphoric acid to generate potassium dihydrogen phosphate; then concentrating the alkaline washing solution at a temperature of 80°C and a stirring rate of 40rpm until all the potassium dihydrogen phosphate crystals are precipitated, and filtering to obtain a potassium dihydrogen phosphate product.

[0090] The iodine adsorption value of the regenerated activated carbon obtained in this example was measured, and the purity of the potassium dihydrogen phosphate product was analyzed. The iodine adsorption value of the regenerated activated carbon was 1346 (mg / g), the potassium dihydrogen phosphate content in the potassium dihydrogen phosphate product was 93wt%, and the rest was impurities.

[0091] Example 5

[0092] The recycling and regeneration method of waste activated carbon provided in this embodiment is basically the same as that in Embodiment 4, except that, in step S400, the 3 wt % nitric acid is replaced by 1 wt % sulfuric acid.

[0093] The iodine adsorption value of the regenerated activated carbon obtained in this example was measured, and the potassium dihydrogen phosphate product was analyzed for purity. The iodine adsorption value of the regenerated activated carbon was 1354 (mg / g), the potassium dihydrogen phosphate content in the potassium dihydrogen phosphate product was 92.5wt%, and the rest was impurities.

[0094] Example 6

[0095] The recycling and regeneration method of waste activated carbon provided in this embodiment is basically the same as that in Embodiment 1, except that, in step S300, 8 wt % of the NaOH solution is replaced by an equal amount of 10 wt % ammonia water.

[0096] The iodine adsorption value of the regenerated activated carbon obtained in this example was measured, and the iodine adsorption value of the regenerated activated carbon was 971 (mg / g).

[0097] Comparative Example 1

[0098] The recycling and regeneration method of waste activated carbon provided in this comparative example is basically the same as that in Example 1, except that in step S400, an equal amount of the aqueous solution containing the surfactant is replaced by pure water.

[0099] The iodine adsorption value of the regenerated activated carbon obtained in this comparative example was measured, and the iodine adsorption value of the regenerated activated carbon was 712 (mg / g).

[0100] It can be seen that the iodine adsorption value of the activated carbon after regeneration in this comparative example is much lower than 963 (mg / g) in Example 1. This is because compared with this comparative example, in Example 1, the alkali-washed carbon is added to an aqueous solution containing a surfactant and stirred and slurried. During this process, the grease remaining on the surface of the alkali-washed carbon is eluted to obtain regenerated activated carbon with higher adsorption capacity.

[0101] Comparative Example 2

[0102] The recycling and regeneration method of waste activated carbon provided in this comparative example is basically the same as that in Example 3, except that, in step S300, the pH value of the KOH solution is adjusted to 10 by controlling the concentration of the KOH solution in this comparative example, and the amount of the KOH solution used in this comparative example is also the same as that in Example 3.

[0103] The iodine adsorption value of the regenerated activated carbon obtained in this comparative example was measured, and the iodine adsorption value of the regenerated activated carbon was 936 (mg / g).

[0104] It can be seen that the iodine adsorption value of the activated carbon after regeneration in this comparative example is lower than 1352 (mg / g) in Example 3. This is because in Example 3, the alkaline solution is controlled to be strongly alkaline, and the amount of short-chain alcohol added to the alkaline solution is 0.45wt%, thereby deeply regenerating the water-washed carbon and obtaining regenerated activated carbon with optimal adsorption capacity.

[0105] Comparative Example 3

[0106] The recycling and regeneration method of waste activated carbon provided in this comparative example is basically the same as that in Example 3, except that, in this comparative example, the pH value of the aqueous solution containing the surfactant is not adjusted, but the acid-washed carbon is directly stirred and slurried in the aqueous solution containing the surfactant for 50 minutes.

[0107] The iodine adsorption value of the regenerated activated carbon obtained in this comparative example was measured, and the iodine adsorption value of the regenerated activated carbon was 1082 (mg / g).

[0108] It can be seen that the iodine adsorption value of the activated carbon after regeneration in this comparative example is lower than 1352 (mg / g) in Example 3. This is because the aqueous solution containing the surfactant in Example 3 is controlled to be alkaline, and the surfactant is added during the stirring and slurrying process of the acid-washed carbon. This can achieve deep elution of impurities such as grease remaining on the surface of the acid-washed carbon, thereby obtaining regenerated activated carbon with optimal adsorption capacity.

[0109] Through the above-mentioned embodiments, comparative examples, and detection of the adsorption iodine value of the regenerated activated carbon, under the conditions of the embodiments of the present invention, activated carbon with a high adsorption iodine value can be regenerated, which solves the technical problems of high energy consumption, poor regeneration effect and complex operation of the existing activated carbon regeneration technology.

[0110] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0111] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for recycling waste activated carbon, characterized in that: include: Obtaining waste activated carbon, wherein the waste activated carbon is activated carbon used for decolorization in the process of preparing inositol and phosphate by hydrolysis of phytate; Add the waste activated carbon into water, stir and slurry for 10 to 40 minutes, and obtain washed carbon after filtering; Adding an alkaline solution to the water-washed carbon, and subjecting the carbon to ultrasonic vibration for 0.5 to 1 h at a temperature of 50 to 80° C. and a vibration frequency of 20 to 50 KHz, and filtering to obtain an alkaline-washed carbon and an alkaline washing liquid; wherein the mass concentration of the alkaline solution is 8 to 13 wt %, and the mass ratio of the water-washed carbon to the alkaline solution is 1:(1 to 3); The alkali-washed carbon is added to an aqueous solution containing a surfactant, stirred and slurried for 10 to 50 minutes, and regenerated activated carbon is obtained after filtering; wherein the mass ratio of the alkali-washed carbon, the surfactant and the water is (80 to 100):0.1:(100 to 200).

2. The method for recycling waste activated carbon according to claim 1, characterized in that: The alkaline solution also includes a short-chain alcohol, wherein the mass ratio of the short-chain alcohol, the alkali and the added solvent water is (0.5-1):(7.2-14.3):(90-110); the mass ratio of the water-washed carbon to the alkaline solution containing the short-chain alcohol is 1:(1-3).

3. The method for recycling waste activated carbon according to claim 2, characterized in that: The short-chain alcohol includes any one or more of methanol, ethanol, and isopropanol; the base includes any one or more of NaOH, KOH, and ammonia water.

4. The method for recycling waste activated carbon according to claim 1, characterized in that: The surfactant includes one or more of sodium fatty alcohol isethionate, dodecyl phosphate, ammonium dodecyl sulfate, sodium dodecyl sulfate, dodecyl phosphate triethanolamine, hexadecyl trimethyl ammonium chloride or amide polyoxyethylene ether magnesium sulfate.

5. The method for recycling waste activated carbon according to claim 1, characterized in that: In the carbon washing step, the mass ratio of the activated carbon to the water is 1:(1-2); and / or, The mass ratio of the alkali-washed carbon to the aqueous solution containing a surfactant is 1:(1-2).

6. The method for recycling waste activated carbon according to claim 1, characterized in that: After obtaining the alkali-washed carbon, before adding the alkali-washed carbon into a surfactant aqueous solution and stirring and slurrying, the method further comprises: Add the alkali-washed carbon into the acid solution, stir and slurry for 0.5 to 1 hour, and obtain the acid-washed carbon after filtering; The mass ratio of the alkali-washed carbon to the acid solution is 1:(1-3), the concentration of the acid solution is 1-3wt%, the temperature of the acid solution is 25-55°C, and the stirring rate is 20-100rpm.

7. The method for recycling waste activated carbon according to claim 6, characterized in that: The acid solution includes 1-3 wt % phosphoric acid, 1-3 wt % hydrochloric acid, 1-3 wt % nitric acid or 1-3 wt % sulfuric acid.

8. A regenerated activated carbon, characterized in that The activated carbon is regenerated by the recycling regeneration method of waste activated carbon according to any one of claims 1 to 7, and the iodine adsorption value of the regenerated activated carbon is 900 to 1400 (mg / g).

9. A method for preparing dihydrogen phosphate, characterized in that: Phosphoric acid is added to the alkaline washing liquid for reaction, wherein the amount of phosphoric acid added is to adjust the pH value of the reaction liquid to 3.2-3.8, and the reaction is carried out at the pH value for 0.5-1h; wherein the alkaline washing liquid is the alkaline washing liquid produced in the recycling regeneration method of waste activated carbon according to any one of claims 1 to 7, and the concentration of the phosphoric acid is 75-85wt%; The reaction solution is concentrated under stirring until crystals are precipitated, and then filtered to obtain a dihydrogen phosphate product; wherein the temperature during the concentration is 70-100° C. and the stirring rate is 20-100 rpm.

10. A dihydrogen phosphate product, characterized in that: The dihydrogen phosphate product is prepared by the method for preparing dihydrogen phosphate according to claim 9, wherein the dihydrogen phosphate content in the dihydrogen phosphate product is 85-95wt%, and the remainder is impurities.

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