Three-dimensional hydrophobic modified activated carbon and preparation method thereof

Abstract

The invention discloses three-dimensional hydrophobic modified activated carbon, which is characterized in that hydrophobic carbon chains are grafted inside and outside activated carbon pores, and the hydrophobic carbon chains are trichlorosilane with different carbon chain lengths. The invention also discloses a preparation method of the three-dimensional hydrophobic modified activated carbon, and the preparation method comprises the following steps: (1) pretreatment: the activated carbon is firstly placed in distilled water for ultrasonic cleaning for 5-10 min, then soaked in a pretreatment activation solution for 5-10 min, and then placed in a drying oven for drying, and the pretreatment activation solution is an ammonia water solution with the pH value of 8-9; (2) three-dimensional modification: taking 5-10 parts by weight of a modifier, dropwise adding the modifier into 20-50 parts by weight of a solvent to obtain a modifier solution, soaking 10-15 parts by weight of pretreated activated carbon into the modifier solution, sealing the whole reaction system, and immediately soaking the reaction system in an ultrasonic environment for 2-4 hours; and (3) post-treatment: cleaning the impregnated activated carbon with a solvent, and carrying out vacuum drying in a vacuum drying oven at 100-150 DEG C for 5-12 hours to obtain the three-dimensional hydrophobic modified activated carbon.

Description

Technical Field

[0001] The invention relates to a three-dimensional hydrophobic modified activated carbon and also relates to a preparation method of the three-dimensional hydrophobic modified activated carbon. Background Art

[0002] As a widely used and inexpensive adsorbent, activated carbon has the advantages of developed pore structure, rich functional groups, high mechanical strength and acid and alkali resistance. It has been widely used to treat various related environmental pollution problems, including sewage purification, treatment of harmful volatile gases (VOCs) and air purification. However, activated carbon still faces a thorny problem in practical application, that is, when facing a liquid or gas environment with water, activated carbon has a large number of oxygen-containing functional groups on its surface, and hydrogen bond interactions make them have a high affinity for water molecules. Therefore, organic pollutants are at a disadvantage in the competitive adsorption with water molecules, and activated carbon will preferentially adsorb water vapor and reach saturation, which ultimately leads to a significant decrease in the adsorption amount of the target organic pollutants and seriously shortens the service life of activated carbon. Therefore, enhancing the waterproof and moisture-proof properties of activated carbon, hydrophobicizing its surface, and retaining the adsorption capacity for organic matter are the key to improving the adsorption capacity, service life and cycle performance of adsorbent materials such as activated carbon for organic matter in complex environments.

[0003] The existing technology is to modify activated carbon through super-hydrophobic nano-coating technology. The organic-inorganic composite nano-coating forms an air film in the water, which effectively isolates the contact between the activated carbon and water molecules. However, if the air film formed by the super-hydrophobic nano-coating is too thick, it will also hinder the contact between the activated carbon and the organic matter in the water; in addition, the nano-composite coating is very easy to be damaged during transportation, so the hydrophobic stability is poor. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a three-dimensional hydrophobic modified activated carbon, which has a three-dimensional hydrophobic structure and does not hinder the contact between the activated carbon and organic matter in the water while making the activated carbon waterproof and moisture-proof. It will not be damaged during transportation and has good hydrophobic stability and durability. Another purpose of the present invention is to provide a method for preparing the above-mentioned three-dimensional hydrophobic modified activated carbon.

[0005] Technical solution: The three-dimensional hydrophobic modified activated carbon described in the present invention has hydrophobic carbon chains grafted both inside and outside the activated carbon pores.

[0006] Wherein, the hydrophobic carbon chain is trichlorosilane with different carbon chain lengths.

[0007] The preparation method of the above three-dimensional hydrophobically modified activated carbon comprises the following steps:

[0008] (1) The activated carbon is first placed in distilled water for ultrasonic cleaning for 5 to 10 minutes, then immersed in a pretreatment activation solution for 5 to 10 minutes, and then placed in an oven for drying; the pretreatment activation solution is an ammonia solution with a pH value of 8 to 9;

[0009] (2) 5 to 10 parts of the modifier are added dropwise to 20 to 50 parts of the solvent to obtain a modifier solution, 10 to 15 parts of the pre-treated activated carbon are immersed in the modifier solution, and the entire reaction system is sealed and immediately placed in an ultrasonic environment for immersion for 2 to 4 hours;

[0010] (3) The impregnated activated carbon is washed with a solvent and then placed in a vacuum drying oven for vacuum drying (high-temperature drying under a vacuum environment is performed to completely volatilize the unreacted trichlorosilane modifier and solvent to avoid them being retained in the pores) to obtain a three-dimensional hydrophobic modified activated carbon.

[0011] The activated carbon is any one of coal, wood or petroleum, and is in the shape of column, granule, powder, fiber or honeycomb, with a specific surface area of ​​800-2000m 2 / g.

[0012] Wherein, in step (1), the drying temperature is 100-150° C. and the drying time is 5-12 hours.

[0013] Wherein, in step (2), the modifier is any one of methyltrichlorosilane, ethyltrichlorosilane, propyltrichlorosilane, butyltrichlorosilane or perfluorotrichlorosilane. Trichlorosilanes of different carbon chain lengths are low surface energy substances, which react with activated carbon to graft hydrophobic groups inside and outside the pore structure of activated carbon, and have little effect on the microporous structure, pore characteristics and specific surface area inside the activated carbon.

[0014] Wherein, in step (2), the solvent is any one of n-hexane, n-heptane, toluene or acetone.

[0015] Wherein, in step (2), when the solvent is water, when preparing the modifier solution, 5 parts by mass of FS-3100 surfactant and 5 to 10 parts by mass of modifier are added to 20 to 50 parts by mass of solvent, and the pH value is adjusted to 8 to 9 with ammonia water to obtain the modifier solution.

[0016] Wherein, in step (2), the ultrasonic treatment parameters are: ultrasonic power is 250-600W, and ultrasonic frequency is 20-40KHz.

[0017] Wherein, in step (3), the drying temperature is 80 to 250° C., and the vacuum drying time is 4 to 12 hours.

[0018] The three-dimensional hydrophobic modified activated carbon of the present invention can enhance the removal ability of activated carbon for multiphase pollutants (liquid emulsified oil, gaseous toluene and toxic algae) while maintaining a high specific surface area. In an aqueous environment containing organic waste, the hydrophobic carbon chain of the three-dimensional hydrophobic modified activated carbon repels water while increasing the affinity for organic matter; therefore, the present invention adopts a covalent bond grafting method to effectively retain the pore structure of the activated carbon while having excellent hydrophobic stability.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant effects: (1) The prior art uses super-hydrophobic nano-coating technology to modify activated carbon, and achieves super-hydrophobicity by constructing a super-hydrophobic shell layer on the outer layer of activated carbon, but does not achieve hydrophobicity in the internal three-dimensional pores. The method of the present invention can graft hydrophobic silane chains to the inside and outside of the activated carbon pores (grafting trichlorosilane with different carbon chain lengths onto the activated carbon pore structure) to form a three-dimensional hydrophobic structure. The obtained hydrophobic activated carbon can avoid clogging the pore size of the activated carbon, thereby reducing the specific surface area of ​​the activated carbon and poor hydrophobic stability; on the other hand, it can greatly reduce the competitive adsorption problem between water molecules and organic matter, and can use the similar compatibility principle of hydrophobic chains to improve the adsorption capacity of activated carbon for multi-phase organic matter, thereby greatly improving the adsorption efficiency and adsorption amount; (2) The sealing treatment during the preparation of activated carbon ensures that the pores are not affected by water molecules in the air during the modification process. The specific surface area decreased by 40% after the modification without sealing process; on the other hand, ultrasonic treatment accelerated the hydrophobic modification process and the diffusion rate of the modifier in the pores. The contact angle of the activated carbon without ultrasonic treatment was below 100, and the removal rate of harmful algal bloom species (Chlorella) and algae organic matter (AOM) in water decreased significantly, both below 85%; (3) The water contact angle of the modified activated carbon from inside to outside was 120-130°, and the change in specific surface area before and after modification was less than 3%; in water or under the condition of relative humidity of 90%, compared with the unmodified, the adsorption amount of organic matter by the modified activated carbon increased by 1-3 times, the adsorption efficiency increased by 2 times, and the removal rate of harmful algal bloom species (Chlorella) and algae organic matter (AOM) in water reached more than 90%; (4) The method of the present invention is a hydrophobic modification method of activated carbon with hydrophobicity and basically no effect on the pore structure, which can be used for efficient adsorption of multi-phase organic matter and improve the removal efficiency and service life of activated carbon in wastewater and waste gas treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The hydrophobic mechanism of the activated carbon is modified by the three-dimensional hydrophobic modified activated carbon and the super-hydrophobic nano-coating coating technology in Example 1;

[0021] Figure 2 Elemental analysis of the three-dimensional hydrophobic modified activated carbon and ordinary activated carbon in Example 1;

[0022] Figure 3The Raman spectrum and infrared spectrum comparison of the three-dimensional hydrophobic modified activated carbon and the ordinary activated carbon in Example 2;

[0023] Figure 4 The adsorption capacity and changes of the three-dimensional hydrophobic modified activated carbon and the ordinary activated carbon for various organic matters in different states (dry state, after adsorbing water vapor, after adsorbing water) in Example 3;

[0024] Figure 5 The static water vapor adsorption and dynamic water vapor adsorption and desorption tests of the three-dimensional hydrophobic modified activated carbon and the ordinary activated carbon in Example 4;

[0025] Figure 6 The COD removal rate of the three-dimensional hydrophobic modified activated carbon and the ordinary activated carbon for oily wastewater in Example 5 is measured;

[0026] Figure 7 The comparison of the adsorption amount of gaseous toluene in dry state and high humidity between the three-dimensional hydrophobic modified activated carbon and the ordinary activated carbon in Example 6;

[0027] Figure 8 The removal rate of heavy oil in water by the three-dimensional hydrophobic modified activated carbon in Example 7 is compared with that of ordinary activated carbon;

[0028] Fig. 9 This is a comparison diagram of the hydrophobic angles of the three-dimensional hydrophobically modified activated carbon and the ordinary activated carbon in Example 8;

[0029] Fig.10 This is a comparison chart of the BET specific surface area of ​​the three-dimensional hydrophobic modified activated carbon and the ordinary activated carbon in Example 8;

[0030] Fig.11 The following are the comparison charts of the adsorption effect of the three-dimensional hydrophobic modified activated carbon and the ordinary activated carbon on the initial algae solution in Example 8; the curve of the reduction of the algae density in the solution by the three-dimensional hydrophobic modified activated carbon and the ordinary activated carbon; and the comparison chart of the final algae removal rate and the AOM removal efficiency;

[0031] Fig.12 This is a comparison chart of the adsorption effects of the three-dimensional hydrophobic modified activated carbon and the ordinary activated carbon on the algae solution and the emulsified oil-water in Example 8;

[0032] Fig.13 The diagram is a diagram of the removal mechanism of organic matter in the air by the three-dimensional hydrophobic modified activated carbon of the present invention;

[0033] Fig.14 The figure is a diagram showing the removal mechanism of underwater emulsion by the three-dimensional hydrophobically modified activated carbon of the present invention;

[0034] Fig.15 This is a diagram of the removal mechanism of algae by the three-dimensional hydrophobic modified activated carbon of the present invention. DETAILED DESCRIPTION

[0035] Example 1

[0036] The preparation method of the three-dimensional hydrophobic modified activated carbon of the present invention comprises the following steps:

[0037] (1) Select coal-based granular activated carbon, first place the activated carbon in distilled water for ultrasonic cleaning for 10 minutes, then soak it in a pretreatment activation solution for 10 minutes, and then place it in an 80°C oven for drying for 12 hours; the pretreatment activation solution is an ammonia solution with a pH value of 8 to 9;

[0038] (2) adding 10 parts by weight of perfluorotrichlorosilane to 50 parts by weight of a distilled water solution containing 5 parts by weight of FS-3100 surfactant and stirring evenly, adjusting the pH value to 8-9 with aqueous ammonia to obtain a modifier solution, then adding 10 parts by weight of activated carbon, and immediately sealing the round-bottom flask; transferring the activated carbon to an ultrasonic environment for immersion reaction for 2 hours, with an ultrasonic power of 250 W and an ultrasonic frequency of 20 kHz;

[0039] (3) After the reaction is completed, the activated carbon is taken out and washed with water for 5 times; the washed activated carbon is placed in a vacuum drying oven and dried at 250° C. for 8 h to obtain a three-dimensional hydrophobic modified activated carbon.

[0040] The difference in hydrophobic mechanism between three-dimensional hydrophobic modified activated carbon and super hydrophobic nano-coating technology for modified activated carbon is shown in Figure 1 . The super-hydrophobic nano-coating technology is used to modify the activated carbon because it achieves hydrophobicity through the shell layer. However, the super-hydrophobic activated carbon rubs against each other during transportation, and the hard super-hydrophobic shell layer is easily damaged, resulting in the loss of hydrophobic properties. The three-dimensional hydrophobic modified activated carbon of the present invention has hydrophobic carbon chains grafted inside and outside the activated carbon pores, and the contact angle of the three-dimensional hydrophobic modified activated carbon is 106°. The super-hydrophobic activated carbon obtained by modifying the activated carbon using the super-hydrophobic nano-coating technology was cut open, and the cross-sectional contact angle was 55°; under the same circumstances, the hydrophobic angle at the cross-section of the three-dimensional hydrophobic modified activated carbon was still as high as 105°, indicating that the hydrophobic stability of the three-dimensional hydrophobic modified activated carbon obtained by the method of the present invention is far superior to the super-hydrophobic activated carbon coated with the existing super-hydrophobic nano-coating.

[0041] The surface of the three-dimensional hydrophobically modified activated carbon contains Cl elements, which indicates that the activated carbon undergoes a condensation reaction with chlorosilane and is grafted with hydrophobic alkyl chains. Figure 2 .

[0042] Table 1 shows the specific surface area and pore structure of the modified activated carbon. The BET specific surface area of ​​the three-dimensional hydrophobic modified activated carbon did not decrease significantly, which also proves that the adsorption capacity of the activated carbon was retained after chlorosilane modification.

[0043] Table 1 Specific surface area and porous properties of activated carbon before and after modification.

[0044]

[0045]

[0046] Example 2

[0047] The method for preparing three-dimensional hydrophobically modified activated carbon of the present invention comprises the following steps:

[0048] (1) Select wood powder activated carbon, first place the activated carbon in distilled water for ultrasonic cleaning for 10 minutes, then soak it in a pretreatment activation solution for 5 minutes, and then place it in a 100°C oven for drying for 12 hours; the pretreatment activation solution is an ammonia solution with a pH value of 8 to 9;

[0049] (2) adding 9.8 parts by mass of ethyltrichlorosilane to 50 parts by mass of acetone, stirring evenly, and then adding 11 parts by mass of activated carbon; transferring the conical flask containing the activated carbon directly to an ultrasonic environment for immersion reaction for 4 hours, with an ultrasonic power of 250 W and an ultrasonic frequency of 20 kHz;

[0050] (3) After the reaction is completed, the activated carbon is taken out and washed with acetone for 5 times; the washed activated carbon is placed in a vacuum drying oven and dried at 150° C. for 8 h to obtain a three-dimensional hydrophobic modified activated carbon.

[0051] Figure 3 a is a comparison of Raman spectra of common activated carbon and three-dimensional hydrophobic modified activated carbon. The carbon structure of the modified activated carbon is almost unchanged compared with that of the common activated carbon. Figure 3 b is a comparison of Fourier transform infrared spectra of ordinary activated carbon and three-dimensional hydrophobic modified activated carbon. The appearance of the methyl and methylene characteristic peaks of the modified activated carbon also confirms the success of the grafting modification. The contact angle of the three-dimensional hydrophobic modified activated carbon is 113°, and the specific surface area is 816.34 m 2 g -1 .

[0052] Example 3

[0053] The method for preparing three-dimensional hydrophobically modified activated carbon of the present invention comprises the following steps:

[0054] (1) Selecting wood activated carbon fiber, firstly, ultrasonically cleaning the activated carbon in distilled water for 10 minutes, then soaking it in a pretreatment activation solution for 10 minutes, and then drying it in a 150°C oven for 12 hours; the pretreatment activation solution is an ammonia solution with a pH value of 8 to 9;

[0055] (2) Add 5 parts by mass of propyltrichlorosilane to 50 parts by mass of n-hexane, stir evenly, then add 10 parts by mass of activated carbon fiber, and immediately seal the round-bottom flask; transfer the activated carbon fiber to an ultrasonic environment and immerse it for 8 hours, the ultrasonic power is 250W, and the ultrasonic frequency is 30KHz;

[0056] (3) After the reaction is completed, the activated carbon fiber is taken out and washed with n-hexane three times; the washed activated carbon fiber is placed in a vacuum drying oven and dried at 200°C in a vacuum environment for 8 hours to obtain a three-dimensional hydrophobic modified activated carbon fiber.

[0057] The static adsorption capacity of ordinary activated carbon fibers and the three-dimensional hydrophobically modified activated carbon fibers prepared in Example 3 after being placed in a dry state, a high humidity environment with a relative humidity of 99%, and water for adsorption saturation was measured. The results are shown in Figure 4 As shown, Figure 4 a is the adsorption capacity of various organic matters by activated carbon fiber in dry state before and after modification; Figure 4 b The adsorption amount of various organic substances by activated carbon fiber before and after modification after adsorbing water vapor; Figure 4 c is the adsorption of various organic substances by activated carbon fibers before and after modification under saturated adsorption water. Due to its good hydrophobic and lipophilic properties, the three-dimensional hydrophobic modified activated carbon fiber has good water repellency to water vapor and water under high humidity and retains the adsorption capacity for organic substances; while the unmodified activated carbon fiber reaches saturation after adsorption of high humidity water vapor and aqueous solution and loses its adsorption capacity for organic substances.

[0058] Example 4

[0059] The preparation method of the three-dimensional hydrophobic modified activated carbon of the present invention comprises the following steps:

[0060] (1) A petroleum-based columnar honeycomb activated carbon was selected, and the activated carbon was first placed in distilled water for ultrasonic cleaning for 10 minutes, then soaked in a pretreatment activation solution for 10 minutes, and then placed in a 150°C oven for drying for 12 hours; the pretreatment activation solution was an ammonia solution with a pH value of 8 to 9;

[0061] (2) adding 9 parts by mass of perfluorotrichlorosilane to 50 parts by mass of n-hexane, stirring evenly, then adding 10 parts by mass of activated carbon, and immediately sealing the round-bottom flask; transferring the activated carbon to an ultrasonic environment for immersion reaction for 4 hours, with an ultrasonic power of 500 W and an ultrasonic frequency of 40 kHz;

[0062] (3) After the reaction is completed, the activated carbon is taken out and washed with n-hexane three times; the washed activated carbon is placed in a vacuum drying oven and dried in an oven at 200° C. for 8 h to obtain a three-dimensional hydrophobic modified activated carbon.

[0063] Static water vapor adsorption and dynamic water vapor adsorption-desorption tests were performed on the three-dimensional hydrophobic modified activated carbon of Example 4. Figure 5 a is the static water vapor adsorption test of honeycomb activated carbon before and after modification at a relative humidity of 99%. The weight gain of the three-dimensional hydrophobic modified activated carbon due to moisture absorption is 15%, while the weight gain of the ordinary activated carbon due to moisture absorption is 45%, and the moisture-proof performance is significant; Figure 5 b is the dynamic water vapor adsorption and desorption isotherm. Figure 5 c is the dynamic water vapor adsorption puncture curve. The three-dimensional hydrophobic modified activated carbon adsorbs less water vapor than ordinary activated carbon, and shows a faster rate of water vapor desorption.

[0064] Example 5

[0065] The preparation method of the three-dimensional hydrophobic modified activated carbon of the present invention comprises the following steps:

[0066] (1) Select coal-based columnar activated carbon, first place the activated carbon in distilled water for ultrasonic cleaning for 10 minutes, then soak it in a pretreatment activation solution for 10 minutes, and then place it in a 150°C oven for drying for 12 hours; the pretreatment activation solution is an ammonia solution with a pH value of 8 to 9;

[0067] (2) 8 parts by mass of butyltrichlorosilane was added to 50 parts by mass of toluene, and the mixture was stirred evenly. Then, 10 parts by mass of activated carbon was added, and the round-bottom flask such as a beaker was immediately sealed; the activated carbon was transferred to an ultrasonic environment and immersed in the reaction for 4 hours, with an ultrasonic power of 250 W and an ultrasonic frequency of 40 kHz;

[0068] (3) After the reaction is completed, the activated carbon is taken out and washed with toluene five times; the washed activated carbon is placed in a vacuum drying oven and dried at 150° C. for 8 h to obtain a three-dimensional hydrophobic modified activated carbon.

[0069] The COD removal rate performance of the three-dimensional hydrophobic modified activated carbon of Example 5 was tested for oily wastewater. The test results showed that the three-dimensional hydrophobic modified activated carbon could completely adsorb the oil droplets dispersed in the oily wastewater. The filtrate after adsorption by ordinary activated carbon showed milky white. Figure 6 a, and some oil droplets are still seen under the optical microscope. Figure 6 ce, while the filtrate after adsorption by three-dimensional hydrophobic modified activated carbon was clear. Figure 6 a, no oil droplets are distributed under an optical microscope, see Figure 6 d. At the same time, in the particle size distribution test, the results showed that the three-dimensional hydrophobic modified activated carbon can completely adsorb the oil droplets in the filtrate, while the ordinary activated carbon can only adsorb part of the oil droplets. The removal rate of COD removal in wastewater was tested. The hydrophobic activated carbon can completely adsorb the oil in the water, while the removal rate of the ordinary activated carbon is only 70%. Figure 6f. The adsorption performance of the three-dimensional hydrophobic modified activated carbon in Example 5 on strong acid, neutral and strong alkaline water-in-oil emulsions (pH values ​​are 1, 7, and 11, respectively) shows that the adsorption performance of the hydrophobic activated carbon on strong acid and strong alkaline water-in-oil emulsions still maintains excellent removal performance, among which the removal rate of the strong acid water-in-oil emulsion is the fastest, and the removal efficiency is still higher than 90%. Therefore, the three-dimensional hydrophobic modified activated carbon has a good oil-water separation effect on the above-mentioned surfactant-containing oily wastewater, see Figure 6 g, 6h.

[0070] Example 6

[0071] The preparation method of the three-dimensional hydrophobic modified activated carbon of the present invention comprises the following steps:

[0072] (1) Petroleum-based powdered activated carbon was first placed in distilled water for ultrasonic cleaning for 10 minutes, then soaked in a pretreatment activation solution for 10 minutes, and then dried in a 100°C oven for 12 hours; the pretreatment activation solution was an ammonia solution with a pH value of 8 to 9;

[0073] (2) adding 12 parts by mass of methyltrichlorosilane to 50 parts by mass of n-heptane, stirring evenly, then adding 10 parts by mass of activated carbon, and immediately sealing the round-bottom flask; transferring the activated carbon to an ultrasonic environment for immersion reaction for 4 hours, with an ultrasonic power of 300 W and an ultrasonic frequency of 20 kHz;

[0074] (3) After the reaction is completed, the activated carbon is taken out and washed with n-heptane for 5 times; the washed activated carbon is placed in a vacuum drying oven and dried at 200° C. for 8 h to obtain a three-dimensional hydrophobic modified activated carbon.

[0075] The adsorption performance of toluene by the three-dimensional hydrophobic modified activated carbon of Example 6 was compared with that of ordinary activated carbon at 90% relative humidity. Figure 7 It can be seen that the three-dimensional hydrophobic modified activated carbon still maintains excellent removal performance for the volatile organic gas toluene under high humidity, and its adsorption capacity for gaseous toluene is much higher than that of ordinary activated carbon both in dry state and under high humidity.

[0076] Example 7

[0077] The preparation method of the three-dimensional hydrophobic modified activated carbon of the present invention comprises the following steps:

[0078] (1) Select wooden columnar activated carbon, first place the activated carbon in distilled water for ultrasonic cleaning for 10 minutes, then soak it in a pretreatment activation solution for 10 minutes, and then place it in a 100°C oven for drying for 12 hours; the pretreatment activation solution is an ammonia solution with a pH value of 8 to 9;

[0079] (2) adding 8 parts by mass of propyltrichlorosilane to 41 parts by mass of n-heptane, stirring evenly, then adding 14 parts by mass of activated carbon, and immediately sealing the round-bottom flask; transferring the activated carbon to an ultrasonic environment for immersion reaction for 3.5 hours, with an ultrasonic power of 250 W and an ultrasonic frequency of 20 kHz;

[0080] (3) After the reaction is completed, the activated carbon is taken out and washed with n-heptane three times; the washed activated carbon is placed in a vacuum drying oven and dried at 200° C. for 8 h to obtain a three-dimensional hydrophobic modified activated carbon.

[0081] The three-dimensional hydrophobic modified activated carbon of Example 7 was compared with the ordinary activated carbon in terms of heavy oil adsorption performance. Figure 8 As shown, the hydrophobic activated carbon maintains a rapid removal effect on the heavy oil stained with methyl red, indicating that the three-dimensional hydrophobic activated carbon has a good adsorption and separation effect on heavy oil in water.

[0082] Example 8

[0083] The method for preparing three-dimensional hydrophobically modified activated carbon of the present invention comprises the following steps:

[0084] (1) Select coal-based columnar activated carbon, first place the activated carbon in distilled water for ultrasonic cleaning for 10 minutes, then soak it in a pretreatment activation solution for 10 minutes, and then place it in a 150°C oven for drying for 12 hours; the pretreatment activation solution is an ammonia solution with a pH value of 8 to 9;

[0085] (2) adding 10 parts by mass of propyltrichlorosilane to 30 parts by mass of n-hexane, stirring evenly, then adding 10 parts by mass of activated carbon, and immediately sealing the round-bottom flask; transferring the activated carbon to an ultrasonic environment for immersion reaction for 4 hours, with an ultrasonic power of 600 W and an ultrasonic frequency of 40 kHz;

[0086] (3) After the reaction is completed, the activated carbon is taken out and washed with n-hexane for 5 times; the washed activated carbon is placed in a vacuum drying oven and dried at 150° C. for 12 h to obtain a three-dimensional hydrophobic modified activated carbon.

[0087] The hydrophobic contact angle of the three-dimensional hydrophobically modified activated carbon in Example 8 is 123.5°, while that of the ordinary activated carbon is only 29.9°. Fig. 9 The specific surface area of ​​the hydrophobic activated carbon after modification did not decrease significantly, as shown in Fig.10 The difference in the adsorption performance of harmful algae and algae toxins between three-dimensional hydrophobic modified activated carbon and ordinary activated carbon is shown in the figure. Fig.11As shown in the figure, the three-dimensional hydrophobic modified activated carbon is very effective in removing Chlorella and AOM, with removal efficiencies of 97.56±6.24% and 96.23±5.46%, respectively. The three-dimensional hydrophobic modified activated carbon not only has a significant effect on algae removal, but also has a significantly better ability to treat oily wastewater than ordinary activated carbon. The adsorption effect is as follows Fig.12 As shown, the removal efficiency of the three-dimensional hydrophobic modified activated carbon is close to 100%.

[0088] Comparative Example 1

[0089] A method for preparing hydrophobically modified activated carbon comprises the following steps:

[0090] (1) Select coal-based columnar activated carbon, first place the activated carbon in distilled water for ultrasonic cleaning for 10 minutes, then soak it in a pretreatment activation solution for 10 minutes, and then place it in a 150°C oven for drying for 12 hours; the pretreatment activation solution is an ammonia solution with a pH value of 8 to 9;

[0091] (2) adding 10 parts by mass of propyltrimethoxysilane to 30 parts by mass of n-hexane, stirring evenly, then adding 10 parts by mass of activated carbon, and immediately sealing the round-bottom flask; transferring the activated carbon to an ultrasonic environment for immersion reaction for 4 hours, with an ultrasonic power of 600 W and an ultrasonic frequency of 40 kHz;

[0092] (3) After the reaction is completed, the activated carbon is taken out and washed with n-hexane for 5 times; the washed activated carbon is placed in a vacuum drying oven and dried at 150° C. for 12 h to obtain hydrophobic modified activated carbon.

[0093] Comparative Example 2

[0094] A method for preparing hydrophobically modified activated carbon comprises the following steps:

[0095] (1) Select coal-based columnar activated carbon, first place the activated carbon in distilled water for ultrasonic cleaning for 10 minutes, then soak it in a pretreatment activation solution for 10 minutes, and then place it in a 150°C oven for drying for 12 hours; the pretreatment activation solution is an ammonia solution with a pH value of 8 to 9;

[0096] (2) adding 10 parts by mass of silicon tetrachloride to 30 parts by mass of n-hexane, stirring evenly, then adding 10 parts by mass of activated carbon, and immediately sealing the round-bottom flask; transferring the activated carbon to an ultrasonic environment for immersion reaction for 4 hours, with an ultrasonic power of 600 W and an ultrasonic frequency of 40 kHz;

[0097] (3) After the reaction is completed, the activated carbon is taken out and washed with n-hexane for 5 times; the washed activated carbon is placed in a vacuum drying oven and dried at 150° C. for 12 h to obtain hydrophobic modified activated carbon.

[0098] Comparative Example 3

[0099] A method for preparing hydrophobically modified activated carbon comprises the following steps:

[0100] (1) Select coal-based columnar activated carbon, first place the activated carbon in distilled water for ultrasonic cleaning for 10 minutes, then soak it in a pretreatment activation solution for 10 minutes, and then place it in a 150°C oven for drying for 12 hours; the pretreatment activation solution is an ammonia solution with a pH value of 8 to 9;

[0101] (2) adding 10 parts by mass of propyltrichlorosilane to 30 parts by mass of n-hexane, stirring evenly, and then adding 10 parts by mass of activated carbon; transferring the round-bottom flask containing the activated carbon to an ultrasonic environment for immersion reaction for 4 hours, with an ultrasonic power of 600 W and an ultrasonic frequency of 40 kHz;

[0102] (3) After the reaction is completed, the activated carbon is taken out and washed with n-hexane for 5 times; the washed activated carbon is placed in a vacuum drying oven and dried at 150° C. for 12 h to obtain hydrophobic modified activated carbon.

[0103] Comparative Example 4

[0104] A method for preparing hydrophobically modified activated carbon comprises the following steps:

[0105] (1) Select coal-based columnar activated carbon, first place the activated carbon in distilled water for ultrasonic cleaning for 10 minutes, then soak it in a pretreatment activation solution for 10 minutes, and then place it in a 150°C oven for drying for 12 hours; the pretreatment activation solution is an ammonia solution with a pH value of 8 to 9;

[0106] (2) adding 10 parts by mass of propyltrichlorosilane to 30 parts by mass of n-hexane, stirring evenly, then adding 10 parts by mass of activated carbon, and immediately sealing the round-bottom flask; transferring the activated carbon to an ultrasonic environment for immersion reaction for 1 hour, with an ultrasonic power of 600 W and an ultrasonic frequency of 40 kHz;

[0107] (3) After the reaction is completed, the activated carbon is taken out and washed with n-hexane for 5 times; the washed activated carbon is placed in a vacuum drying oven and dried at 150° C. for 12 h to obtain hydrophobic modified activated carbon.

[0108] Comparative Example 5

[0109] A method for preparing hydrophobically modified activated carbon comprises the following steps:

[0110] (1) Select coal-based columnar activated carbon, first place the activated carbon in distilled water for ultrasonic cleaning for 10 minutes, then soak it in a pretreatment activation solution for 10 minutes, and then place it in a 150°C oven for drying for 12 hours; the pretreatment activation solution is an ammonia solution with a pH value of 8 to 9;

[0111] (2) adding 10 parts by mass of propyltrichlorosilane to 30 parts by mass of n-hexane, stirring evenly, then adding 10 parts by mass of activated carbon, and immediately sealing the round-bottom flask; transferring the activated carbon to an ultrasonic environment for immersion reaction for 4 hours, with an ultrasonic power of 600 W and an ultrasonic frequency of 40 kHz;

[0112] (3) After the reaction is completed, the activated carbon is taken out and washed with n-hexane for 5 times; the washed activated carbon is placed in a vacuum drying oven and dried in an oven at 150° C. for 12 h to obtain hydrophobically modified activated carbon.

[0113] Comparative Example 6

[0114] A method for preparing hydrophobically modified activated carbon comprises the following steps:

[0115] (1) Select coal-based columnar activated carbon, first place the activated carbon in distilled water for ultrasonic cleaning for 10 minutes, and then place it in a 150°C oven to dry for 12 hours;

[0116] (2) adding 10 parts by mass of propyltrichlorosilane to 30 parts by mass of n-hexane, stirring evenly, then adding 10 parts by mass of activated carbon, and immediately sealing the round-bottom flask; transferring the activated carbon to an ultrasonic environment for immersion reaction for 4 hours, with an ultrasonic power of 600 W and an ultrasonic frequency of 40 kHz;

[0117] (3) After the reaction is completed, the activated carbon is taken out and washed with n-hexane for 5 times; the washed activated carbon is placed in a vacuum drying oven and dried at 150° C. for 12 h to obtain hydrophobic modified activated carbon.

[0118] The hydrophobic activated carbons prepared in Examples 1 to 8 and Comparative Examples 1 to 6 were subjected to adsorption performance tests on emulsion and Chlorella under the same conditions. The contact angles of the hydrophobic activated carbons prepared in Examples 1 to 8 and Comparative Examples 1 to 6 and the removal efficiencies of the emulsion and Chlorella are shown in Table 2.

[0119] Table 2

[0120]

[0121]

[0122]

Claims

1. A three-dimensional hydrophobic modified activated carbon, characterized in that: Hydrophobic carbon chains are grafted both inside and outside the activated carbon pores.

2. The three-dimensional hydrophobic modified activated carbon according to claim 1, characterized in that: The hydrophobic carbon chains are trichlorosilanes with different carbon chain lengths.

3. The method for preparing the three-dimensional hydrophobically modified activated carbon according to claim 1, characterized in that: The steps include: (1) Pretreatment: The activated carbon is first placed in distilled water for ultrasonic cleaning for 5 to 10 minutes, then soaked in a pretreatment activation solution for 5 to 10 minutes, and then dried in an oven. The pretreatment activation solution is an ammonia solution with a pH value of 8 to 9; (2) Three-dimensional modification: 5 to 10 parts of a modifier are added dropwise to 20 to 50 parts of a solvent to obtain a modifier solution, 10 to 15 parts of pre-treated activated carbon are immersed in the modifier solution, and the entire reaction system is sealed and immediately placed in an ultrasonic environment for immersion for 2 to 4 hours; (3) Post-treatment: The impregnated activated carbon is cleaned with a solvent and then placed in a vacuum drying oven for vacuum drying to obtain a three-dimensional hydrophobic modified activated carbon.

4. The method for preparing three-dimensional hydrophobic modified activated carbon according to claim 3, characterized in that: In step (1), the drying temperature is 100 to 150° C. and the drying time is 5 to 12 hours.

5. The method for preparing three-dimensional hydrophobic modified activated carbon according to claim 3, characterized in that: In step (2), the modifier is any one of methyltrichlorosilane, ethyltrichlorosilane, propyltrichlorosilane, butyltrichlorosilane or perfluorotrichlorosilane.

6. The method for preparing three-dimensional hydrophobic modified activated carbon according to claim 3, characterized in that: In step (2), the solvent is any one of n-hexane, n-heptane, toluene or acetone.

7. The method for preparing three-dimensional hydrophobic modified activated carbon according to claim 3, characterized in that: In step (2), when the solvent is water, when preparing the modifier solution, 5 parts by weight of FS-3100 surfactant and 5 to 10 parts by weight of modifier are added to 20 to 50 parts by weight of solvent, and the pH value is adjusted to 8 to 9 with aqueous ammonia to obtain a modifier solution.

8. The method for preparing three-dimensional hydrophobic modified activated carbon according to claim 3, characterized in that: In step (2), the ultrasonic treatment parameters are: ultrasonic power of 250 to 600 W, and ultrasonic frequency of 20 to 40 KHz.

9. The method for preparing three-dimensional hydrophobic modified activated carbon according to claim 3, characterized in that: In step (3), the drying temperature is 80 to 250° C., and the vacuum drying time is 4 to 12 hours.

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