Low-ash purified water active carbon and method for preparing the same

Abstract

The present application relates to a kind of low ash water purification activated carbon and its preparation method, belong to activated carbon preparation technical field.The oil tea shell is treated in sodium hydroxide solution and mixed acid solution in turn in the present application, is activated by phosphoric acid method, is centrifuged after being blown by water vapor with hydrochloric acid solution ultrasonic, and low ash water purification activated carbon is obtained.The oil tea shell is placed in sodium hydroxide solution in the present application, heated and pressurized to promote sodium hydroxide to enter the inside of oil tea shell, promote lignin to form oxidized lignin, improve the hydrophilicity of system, not only promote Si and Al element to be removed and dissolved, and subsequent ash in mixed acid solution is removed and dissolved, but also prevent subsequent high temperature process from causing activated carbon cracking caused by lignin rapid cracking, hydrochloric acid and oxalic acid can synergistically improve the removal and dissolution of ash, water vapor blowing makes polyphosphoric acid absorb water and form gel state, the adsorption force of polyphosphoric acid and activated carbon surface is initially weakened by the blowing force of water vapor, ultrasonic treatment is combined with centrifugal dehydration to synergistically promote the removal of polyphosphoric acid.

Description

Technical Field

[0001] This invention belongs to the field of activated carbon preparation technology, and relates to a low-ash activated carbon for water purification and its preparation method. Background Technology

[0002] Activated carbon is a highly efficient carbonaceous adsorbent material with a well-developed pore structure, large specific surface area, and strong selective adsorption capacity. It is widely used in chemical, pharmaceutical, food, and environmental protection industries. The basic structure of activated carbon determines its unique value in applications. Structurally, activated carbon is composed of a large number of graphite microcrystals. Different types of microcrystals exhibit subtle differences in size and orientation, and their surfaces often possess various types of functional groups such as hydroxyl and carboxyl groups. The internal pores also vary in size. Due to its porous nature, it provides a large internal surface area and strong adsorption capacity. This allows it to meet the needs of gas-phase adsorption and also serve as a catalyst carrier. A variety of raw materials can be used to prepare activated carbon, including coal, wood, bamboo, and fruit shells. Among these, camellia oil shells, when used as a raw material, produce activated carbon with a large specific surface area and strong adsorption capacity, making it a high-quality raw material. Fruit shell activated carbon produced by the phosphoric acid method has many mesopores, making it suitable for adsorbing large molecular impurities. Furthermore, the phosphoric acid method produces less pollution and has become the main method for producing fruit shell activated carbon. However, in the production of activated carbon using the phosphoric acid method, the phosphoric acid on the surface of the activated carbon is converted into polyphosphoric acid under high temperature conditions and adsorbed into the pores of the activated carbon. This not only reduces the adsorption performance of the activated carbon but also increases its ash content. Summary of the Invention

[0003] The purpose of this invention is to provide a low-ash activated carbon for water purification and its preparation method, belonging to the field of activated carbon preparation technology. This invention involves placing cleaned camellia oleifera shells in a sodium hydroxide solution under heating and pressure with stirring. After removal, the shells are washed with water, then immersed in a mixed acid solution under heating and pressure. After removal, the shells are washed with water, and a phosphoric acid solution is added for pretreatment with increased temperature. High-temperature activation is then performed, followed by steam purging and addition to a hydrochloric acid solution. After ultrasonic treatment, centrifugation for dehydration, washing with water, and drying, low-ash activated carbon for water purification is obtained. This invention involves placing the cleaned camellia oleifera shells in a sodium hydroxide solution and heating and pressurizing them to allow sodium hydroxide to penetrate the interior of the shells, promoting the formation of oxylignin from lignin and increasing the hydrophilicity of the system. This not only promotes the removal and dissolution of Si and Al elements and the subsequent removal and dissolution of ash in the mixed acid solution, but also prevents the rapid decomposition of lignin during the subsequent high-temperature process, which could cause cracking of the activated carbon. The mixed acid composed of hydrochloric acid and oxalic acid can synergistically improve the removal and dissolution of ash. The activated carbon activated by the phosphoric acid method contains polyphosphoric acid and other components in its pores. Water vapor purging causes the polyphosphoric acid to absorb water and form a gel state, changing its volume. Combined with the purging force of water vapor, the adsorption force between polyphosphoric acid and the surface of activated carbon is initially weakened, promoting the desorption of polyphosphoric acid from activated carbon and its dissolution in the subsequent hydrochloric acid solution. Ultrasonic treatment combined with centrifugal dehydration synergistically promotes the removal of polyphosphoric acid.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A method for preparing low-ash activated carbon for water purification, the method comprising the following steps:

[0006] (1) After cleaning the camellia shells, place them in a sodium hydroxide solution and stir under heating and pressure. After removing them, wash them with water to obtain pretreated camellia shells.

[0007] (2) The pretreated camellia shells were soaked in a mixed acid solution under heating and pressure, and then washed with water to obtain acid-soaked camellia shells.

[0008] (3) After mixing the acid-soaked tea leaves with phosphoric acid solution, the mixture is heated for pretreatment and then activated at high temperature to obtain pre-made activated carbon;

[0009] (4) The pre-made activated carbon is purged with steam, then added to hydrochloric acid solution, ultrasonically treated, centrifuged to dehydrate, washed with water and dried to obtain low ash activated carbon for water purification.

[0010] As a preferred technical solution of the present invention, the sodium hydroxide solution in step (1) has a mass concentration of 8-13%, and the ratio of the amount of camellia seed shell to sodium hydroxide solution is 1g:5-10mL.

[0011] As a preferred technical solution of the present invention, the heating and pressurizing temperature in step (1) is 120-160℃, the pressure is 600-800kPa, and the stirring reaction time is 2-4h.

[0012] As a preferred technical solution of the present invention, the mixed acid solution in step (2) is a mixed aqueous solution of hydrochloric acid and oxalic acid, wherein the concentration of hydrochloric acid in the mixed aqueous solution is 2-4 mol / L and the concentration of oxalic acid is 3-5 mol / L, and the ratio of the amount of pretreated camellia shell to the amount of mixed acid solution is 1g:8-15mL.

[0013] As a preferred technical solution of the present invention, the heating and pressurizing temperature in step (2) is 35-50℃, the pressure is 400-500kPa, and the soaking time is 1-2h.

[0014] As a preferred embodiment of the present invention, the mass concentration of the phosphoric acid solution in step (3) is 25-40%, and the mass ratio of the acid-soaked tea seed shell to the phosphoric acid solution is 1:1.2-1.4.

[0015] As a preferred technical solution of the present invention, the preheating temperature in step (3) is 120-135℃, the preheating time is 60-80min, the high-temperature activation temperature is 450-550℃, and the high-temperature activation time is 2-3h.

[0016] As a preferred technical solution of the present invention, the flow rate of the steam purging in step (4) is 10-20 m / s, the steam purging time is 1-3 h, the concentration of the hydrochloric acid solution is 6-8 mol / L, and the ratio of the amount of pre-prepared activated carbon to hydrochloric acid solution is 1 g: 12-16 mL.

[0017] As a preferred technical solution of the present invention, the ultrasonic frequency of the ultrasonic treatment in step (4) is 25-30kHz, the ultrasonic treatment time is 60-90min, the centrifugal dehydration speed is 800-1500rpm, and the centrifugal dehydration time is 30-50min.

[0018] The above-described preparation method yields low-ash activated carbon for water purification.

[0019] The beneficial effects of this invention are:

[0020] (1) The lignin content in camellia shells is very high. This invention utilizes this characteristic to place the cleaned camellia shells in a sodium hydroxide solution and heat and pressurize them. The high pressure promotes the sodium hydroxide to enter the interior of the camellia shells, and the high temperature and high pressure conditions promote the formation of oxylignin from lignin, which improves the hydrophilicity of the system. This not only promotes the removal and dissolution of Si and Al elements and the removal and dissolution of ash in the mixed acid solution, but also prevents the rapid decomposition of lignin during the subsequent high temperature process, which could cause the activated carbon to crack.

[0021] (2) The present invention uses a mixed acid composed of hydrochloric acid and oxalic acid to heat and pressurize the pretreated camellia shells for soaking, which can synergistically improve the removal and dissolution of ash in the camellia shells;

[0022] (3) In this invention, after activation by phosphoric acid, phosphoric acid is converted into polyphosphoric acid and other components under high temperature conditions, which are adsorbed in the pores of activated carbon. Water vapor purging causes polyphosphoric acid to absorb water and form a gel state, which changes the volume and initially reduces the binding force between polyphosphoric acid and activated carbon. Combined with the purging force of water vapor, the adsorption force between polyphosphoric acid and the surface of activated carbon is further weakened, promoting the desorption of polyphosphoric acid and activated carbon and its dissolution in the subsequent hydrochloric acid solution.

[0023] (4) The present invention uses ultrasonic treatment combined with centrifugal dehydration to synergistically promote the release of polyphosphoric acid from the pores of activated carbon. Detailed Implementation

[0024] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0025] Example 1

[0026] A method for preparing low-ash activated carbon for water purification, the method comprising the following steps:

[0027] (1) After cleaning the camellia oleifera shells, they were placed in a 10% sodium hydroxide solution at a ratio of 1g:5mL. The mixture was stirred and reacted for 2.8h at a temperature of 135℃ and a pressure of 700kPa. After being removed and washed with water, the pretreated camellia oleifera shells were obtained.

[0028] (2) The pretreated camellia shells were placed in a mixed acid solution containing 3 mol / L hydrochloric acid and 3.5 mol / L oxalic acid at a ratio of 1 g: 12 mL. The solution was soaked for 1 h at 38 °C and 450 kPa pressure. After being removed, the shells were washed with water to obtain acid-soaked camellia shells.

[0029] (3) The acid-soaked tea leaves and a 30% phosphoric acid solution were mixed at a mass ratio of 1:1.2 and then heated to 125℃ for 70 min for pretreatment. Then, the mixture was activated at 500℃ for 2.8 h to obtain pre-made activated carbon.

[0030] (4) The pre-made activated carbon was purged with steam at a flow rate of 13 m / s for 1.5 h. Then the pre-made activated carbon was added to a hydrochloric acid solution with a concentration of 6 mol / L at a ratio of 1 g: 15 mL. The solution was ultrasonically treated at a frequency of 28 kHz for 70 min. After filtration, the activated carbon was centrifuged at a speed of 1000 rpm for 35 min to remove water, washed with water, and dried to obtain water purification activated carbon with low ash content.

[0031] The above-described preparation method yields low-ash activated carbon for water purification.

[0032] Example 2

[0033] A method for preparing low-ash activated carbon for water purification, the method comprising the following steps:

[0034] (1) After cleaning the camellia oleifera shells, they were placed in a sodium hydroxide solution with a mass concentration of 8% at a ratio of 1g:10mL. The mixture was stirred and reacted for 3h at a temperature of 150℃ and a pressure of 620kPa. After being removed and washed with water, the pretreated camellia oleifera shells were obtained.

[0035] (2) The pretreated camellia shells were placed in a mixed acid solution containing 4 mol / L hydrochloric acid and 4 mol / L oxalic acid at a ratio of 1 g: 8 mL, and soaked for 1.5 h at 45 °C and 400 kPa pressure. After being removed, they were washed with water to obtain acid-soaked camellia shells.

[0036] (3) The acid-soaked tea leaves and a 25% phosphoric acid solution were mixed at a mass ratio of 1:1.4 and then heated to 130℃ for 65 min for pretreatment. Then, the mixture was activated at 550℃ for 2 h to obtain pre-made activated carbon.

[0037] (4) The pre-made activated carbon was purged with steam at a flow rate of 18 m / s for 1.2 h. Then the pre-made activated carbon was added to a hydrochloric acid solution with a concentration of 8 mol / L at a ratio of 1 g: 12 mL. The solution was ultrasonically treated at a frequency of 28 kHz for 75 min. After filtration, the activated carbon was centrifuged at a speed of 900 rpm for 45 min to remove water, washed with water, and dried to obtain water purification activated carbon with low ash content.

[0038] The above-described preparation method yields low-ash activated carbon for water purification.

[0039] Example 3

[0040] A method for preparing low-ash activated carbon for water purification, the method comprising the following steps:

[0041] (1) After cleaning the camellia oleifera shells, they were placed in an 8% sodium hydroxide solution at a ratio of 1g:8mL. The mixture was stirred and reacted for 2 hours at a temperature of 160℃ and a pressure of 800kPa. After being removed and washed with water, the pretreated camellia oleifera shells were obtained.

[0042] (2) The pretreated camellia shells were placed in a mixed acid solution containing 2 mol / L hydrochloric acid and 5 mol / L oxalic acid at a ratio of 1 g: 15 mL. The solution was soaked for 2 h at 40 °C and 500 kPa pressure. After being removed, the shells were washed with water to obtain acid-soaked camellia shells.

[0043] (3) The acid-soaked tea leaves and a 40% phosphoric acid solution were mixed at a mass ratio of 1:1.3 and then heated to 120℃ for 60 min for pretreatment. Then, the mixture was activated at 450℃ for 3 h to obtain pre-made activated carbon.

[0044] (4) The pre-made activated carbon was purged with steam at a flow rate of 20 m / s for 1 h. Then the pre-made activated carbon was added to a hydrochloric acid solution with a concentration of 6 mol / L at a ratio of 1 g: 16 mL. The solution was ultrasonically treated at a frequency of 25 kHz for 90 min. After filtration, the activated carbon was centrifuged at a speed of 1500 rpm for 30 min to remove water, washed with water, and dried to obtain water purification activated carbon with low ash content.

[0045] The above-described preparation method yields low-ash activated carbon for water purification.

[0046] Comparative Example 1

[0047] A method for preparing low-ash activated carbon for water purification, the method comprising the following steps:

[0048] (1) After cleaning the camellia oleifera shells, place them in an 8% sodium hydroxide solution at a ratio of 1g:8mL, stir for 2 hours at room temperature and pressure, remove and wash with water to obtain pretreated camellia oleifera shells.

[0049] (2) The pretreated camellia shells were placed in a mixed acid solution containing 2 mol / L hydrochloric acid and 5 mol / L oxalic acid at a ratio of 1 g: 15 mL. The solution was soaked for 2 h at 40 °C and 500 kPa pressure. After being removed, the shells were washed with water to obtain acid-soaked camellia shells.

[0050] (3) The acid-soaked tea leaves and a 40% phosphoric acid solution were mixed at a mass ratio of 1:1.3 and then heated to 120℃ for 60 min for pretreatment. Then, the mixture was activated at 450℃ for 3 h to obtain pre-made activated carbon.

[0051] (4) The pre-made activated carbon was purged with steam at a flow rate of 20 m / s for 1 h. Then the pre-made activated carbon was added to a hydrochloric acid solution with a concentration of 6 mol / L at a ratio of 1 g: 16 mL. The solution was ultrasonically treated at a frequency of 25 kHz for 90 min. After filtration, the activated carbon was centrifuged at a speed of 1500 rpm for 30 min to remove water, washed with water, and dried to obtain water purification activated carbon with low ash content.

[0052] The above-described preparation method yields low-ash activated carbon for water purification.

[0053] Comparative Example 2

[0054] A method for preparing low-ash activated carbon for water purification, the method comprising the following steps:

[0055] (1) After cleaning the camellia oleifera shells, they were placed in an 8% sodium hydroxide solution at a ratio of 1g:8mL. The mixture was stirred and reacted for 2 hours at a temperature of 160℃ and a pressure of 800kPa. After being removed and washed with water, the pretreated camellia oleifera shells were obtained.

[0056] (2) The pretreated camellia shells were placed in a 7 mol / L hydrochloric acid solution at a ratio of 1 g: 15 mL and soaked for 2 h at 40 °C and 500 kPa pressure. After being removed, they were washed with water to obtain acid-soaked camellia shells.

[0057] (3) The acid-soaked tea leaves and a 40% phosphoric acid solution were mixed at a mass ratio of 1:1.3 and then heated to 120℃ for 60 min for pretreatment. Then, the mixture was activated at 450℃ for 3 h to obtain pre-made activated carbon.

[0058] (4) The pre-made activated carbon was purged with steam at a flow rate of 20 m / s for 1 h. Then the pre-made activated carbon was added to a hydrochloric acid solution with a concentration of 6 mol / L at a ratio of 1 g: 16 mL. The solution was ultrasonically treated at a frequency of 25 kHz for 90 min. After filtration, the activated carbon was centrifuged at a speed of 1500 rpm for 30 min to remove water, washed with water, and dried to obtain water purification activated carbon with low ash content.

[0059] The above-described preparation method yields low-ash activated carbon for water purification.

[0060] Comparative Example 3

[0061] A method for preparing low-ash activated carbon for water purification, the method comprising the following steps:

[0062] (1) After cleaning the camellia oleifera shells, they were placed in an 8% sodium hydroxide solution at a ratio of 1g:8mL. The mixture was stirred and reacted for 2 hours at a temperature of 160℃ and a pressure of 800kPa. After being removed and washed with water, the pretreated camellia oleifera shells were obtained.

[0063] (2) The pretreated camellia oleifera shells were placed in an oxalic acid solution with a concentration of 7 mol / L at a ratio of 1 g: 15 mL, and soaked for 2 h at a temperature of 40℃ and a pressure of 500 kPa. After being taken out, they were washed with water to obtain acid-soaked camellia oleifera shells.

[0064] (3) The acid-soaked tea leaves and a 40% phosphoric acid solution were mixed at a mass ratio of 1:1.3 and then heated to 120℃ for 60 min for pretreatment. Then, the mixture was activated at 450℃ for 3 h to obtain pre-made activated carbon.

[0065] (4) The pre-made activated carbon was purged with steam at a flow rate of 20 m / s for 1 h. Then the pre-made activated carbon was added to a hydrochloric acid solution with a concentration of 6 mol / L at a ratio of 1 g: 16 mL. The solution was ultrasonically treated at a frequency of 25 kHz for 90 min. After filtration, the activated carbon was centrifuged at a speed of 1500 rpm for 30 min to remove water, washed with water, and dried to obtain water purification activated carbon with low ash content.

[0066] The above-described preparation method yields low-ash activated carbon for water purification.

[0067] Comparative Example 4

[0068] A method for preparing low-ash activated carbon for water purification, the method comprising the following steps:

[0069] (1) After cleaning the camellia oleifera shells, they were placed in an 8% sodium hydroxide solution at a ratio of 1g:8mL. The mixture was stirred and reacted for 2 hours at a temperature of 160℃ and a pressure of 800kPa. After being removed and washed with water, the pretreated camellia oleifera shells were obtained.

[0070] (2) The pretreated camellia shells were placed in a mixed acid solution containing 2 mol / L hydrochloric acid and 5 mol / L oxalic acid at a ratio of 1 g: 15 mL. The solution was soaked for 2 h at 40 °C and 500 kPa pressure. After being removed, the shells were washed with water to obtain acid-soaked camellia shells.

[0071] (3) The acid-soaked tea leaves and a 40% phosphoric acid solution were mixed at a mass ratio of 1:1.3 and then heated to 120℃ for 60 min for pretreatment. Then, the mixture was activated at 450℃ for 3 h to obtain pre-made activated carbon.

[0072] (4) Add the pre-made activated carbon to a 6 mol / L hydrochloric acid solution at a ratio of 1 g: 16 mL, sonicate at 25 kHz for 90 min, filter, centrifuge at 1500 rpm for 30 min to dehydrate, wash with water, and dry to obtain low ash activated carbon for water purification.

[0073] The above-described preparation method yields low-ash activated carbon for water purification.

[0074] Comparative Example 5

[0075] A method for preparing low-ash activated carbon for water purification, the method comprising the following steps:

[0076] (1) After cleaning the camellia oleifera shells, they were placed in an 8% sodium hydroxide solution at a ratio of 1g:8mL. The mixture was stirred and reacted for 2 hours at a temperature of 160℃ and a pressure of 800kPa. After being removed and washed with water, the pretreated camellia oleifera shells were obtained.

[0077] (2) The pretreated camellia shells were placed in a mixed acid solution containing 2 mol / L hydrochloric acid and 5 mol / L oxalic acid at a ratio of 1 g: 15 mL. The solution was soaked for 2 h at 40 °C and 500 kPa pressure. After being removed, the shells were washed with water to obtain acid-soaked camellia shells.

[0078] (3) The acid-soaked tea leaves and a 40% phosphoric acid solution were mixed at a mass ratio of 1:1.3 and then heated to 120℃ for 60 min for pretreatment. Then, the mixture was activated at 450℃ for 3 h to obtain pre-made activated carbon.

[0079] (4) The pre-made activated carbon was purged with steam at a flow rate of 20 m / s for 1 h. Then the pre-made activated carbon was added to a hydrochloric acid solution with a concentration of 6 mol / L at a ratio of 1 g: 16 mL. The solution was ultrasonically treated at a frequency of 25 kHz for 120 min. After filtration, the activated carbon was washed with water and dried to obtain water purification activated carbon with low ash content.

[0080] The above-described preparation method yields low-ash activated carbon for water purification.

[0081] Comparative Example 6

[0082] A method for preparing low-ash activated carbon for water purification, the method comprising the following steps:

[0083] (1) After cleaning the camellia oleifera shells, they were placed in an 8% sodium hydroxide solution at a ratio of 1g:8mL. The mixture was stirred and reacted for 2 hours at a temperature of 160℃ and a pressure of 800kPa. After being removed and washed with water, the pretreated camellia oleifera shells were obtained.

[0084] (2) The pretreated camellia shells were placed in a mixed acid solution containing 2 mol / L hydrochloric acid and 5 mol / L oxalic acid at a ratio of 1 g: 15 mL. The solution was soaked for 2 h at 40 °C and 500 kPa pressure. After being removed, the shells were washed with water to obtain acid-soaked camellia shells.

[0085] (3) The acid-soaked tea leaves and a 40% phosphoric acid solution were mixed at a mass ratio of 1:1.3 and then heated to 120℃ for 60 min for pretreatment. Then, the mixture was activated at 450℃ for 3 h to obtain pre-made activated carbon.

[0086] (4) Use steam to purge the pre-made activated carbon at a flow rate of 20 m / s for 1 h. Then add the pre-made activated carbon to a hydrochloric acid solution with a concentration of 6 mol / L at a ratio of 1 g: 16 mL. Centrifuge at 1500 rpm for 120 min to dehydrate, wash with water, and dry to obtain low ash activated carbon for water purification.

[0087] The above-described preparation method yields low-ash activated carbon for water purification.

[0088] Performance testing

[0089] The low-ash activated carbon for water purification prepared in Examples 1-3 and Comparative Examples 1-6 was tested for ash content according to GB / T14296.8-2015 and GB / T12496.3-1999. The cracking rate refers to the proportion of camellia shells with cracks or breaks on the surface after activation to the total number of camellia shells. The test results are shown in Table 1 below.

[0090] Table 1

[0091]

[0092]

[0093] The test results above show that, in Comparative Example 1, based on Example 3, the sodium hydroxide treatment conditions were changed to room temperature and pressure. Because sodium hydroxide has poor permeability inside the camellia shell at room temperature and pressure and cannot convert lignin into oxidized lignin, the activated carbon ash content and cracking rate significantly increased. In Comparative Example 2, based on Example 3, only hydrochloric acid was used to soak the pretreated camellia shells, resulting in a decrease in the iodine value of the activated carbon and an increase in ash content. In Comparative Example 3, based on Example 3, only oxalic acid was used to soak the pretreated camellia shells, resulting in a decrease in the iodine value of the activated carbon and an increase in ash content. In Comparative Example 4, based on Example 3, no steam purging was performed on the acid-soaked camellia shells, resulting in a significant decrease in the iodine value of the activated carbon and a significant increase in ash content. In Comparative Example 5, based on Example 3, no centrifugal dehydration was performed on the pre-prepared activated carbon, resulting in a significant decrease in the iodine value of the activated carbon and a significant increase in ash content. In Comparative Example 6, based on Example 3, no ultrasonic treatment was performed on the pre-prepared activated carbon, resulting in a significant decrease in the iodine value of the activated carbon and a significant increase in ash content.

[0094] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for producing a low-ash, purified water activated carbon, characterized by, The preparation method of the water purification activated carbon comprises the following steps: (1) washing the oil tea shell and then stirring and reacting in a sodium hydroxide solution under heating and pressurization, and then washing with water to obtain pretreated oil tea shell; (2) soaking the pretreated oil tea shell in a mixed acid solution under heating and pressurization, and then washing with water to obtain acid-soaked oil tea shell; (3) mixing the acid-soaked oil tea shell with a phosphoric acid solution, then pre-treating by heating, and then high-temperature activation to obtain a pre-prepared activated carbon; (4) purging the pre-prepared activated carbon with water vapor, then adding the pre-prepared activated carbon into a hydrochloric acid solution, then performing ultrasonic treatment, then centrifugal dewatering, then washing with water, and then drying to obtain a low-ash water purification activated carbon; In step (1), the heating and pressurization temperature is 120-160 DEG C, the pressure is 600-800 kPa, and the stirring and reacting time is 2-4 h. In step (2), the heating and pressurization temperature is 35-50 DEG C, the pressure is 400-500 kPa, and the soaking time is 1-2 h.

2. A process for the preparation of a low ash, water-clarifying activated carbon according to claim 1, characterized in that In step (1), the mass concentration of the sodium hydroxide solution is 8-13%, and the use amount ratio of the oil tea shell to the sodium hydroxide solution is 1g:5-10 mL.

3. A process for the preparation of a low ash, water-purifying activated carbon according to claim 1, characterized in that, In step (2), the mixed acid solution is a mixed aqueous solution of hydrochloric acid and oxalic acid, the concentration of the hydrochloric acid in the mixed aqueous solution is 2-4 mol / L, the concentration of the oxalic acid is 3-5 mol / L, and the use amount ratio of the pretreated oil tea shell to the mixed acid solution is 1g:8-15 mL.

4. A process for the preparation of a low ash, water-purifying activated carbon according to claim 1, characterized in that, In step (3), the mass concentration of the phosphoric acid solution is 25-40%, and the mass ratio of the acid-soaked oil tea shell to the phosphoric acid solution is 1:1.2-1.

4.

5. A process for the preparation of a low ash, water-purifying activated carbon according to claim 1, characterized in that, In step (3), the pre-treating temperature by heating is 120-135 DEG C, the pre-treating time by heating is 60-80 min, the high-temperature activation temperature is 450-550 DEG C, and the high-temperature activation time is 2-3 h.

6. A process for the preparation of a low ash, water-purifying activated carbon according to claim 1, characterized in that, In step (4), the flow rate of the water vapor purging is 10-20 m / s, the water vapor purging time is 1-3 h, the concentration of the hydrochloric acid solution is 6-8 mol / L, and the use amount ratio of the pre-prepared activated carbon to the hydrochloric acid solution is 1g:12-16 mL.

7. A process for the preparation of a low ash, water-purifying activated carbon according to claim 1, characterized in that, In step (4), the ultrasonic frequency of the ultrasonic treatment is 25-30 kHz, the ultrasonic treatment time is 60-90 min, the centrifugal dewatering speed is 800-1500 rpm, and the centrifugal dewatering time is 30-50 min.

8. A low-ash water purification activated carbon prepared by the preparation method of any one of claims 1-7.

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