Chemical-modification-free activated carbon composite adsorbent, preparation method and application

Abstract

The invention discloses a modification-free composite adsorbent for coking wastewater. The modification-free composite adsorbent comprises the following components: 55-65 wt% of activated carbon, 25-30 wt% of polystyrene microspheres and 10-15 wt% of montmorillonite, the activated carbon is plant-based activated carbon, the specific surface area is greater than or equal to 1000m < 2 > / g, and the iodine value is greater than or equal to The polystyrene microspheres are intrinsic polystyrene, and the degree of crosslinking is 30-50%. The invention also discloses a preparation method of the adsorbent and an application of the adsorbent in efficient removal of COD in high-salt coking wastewater. The adsorbent is not subjected to any chemical modification treatment, is free of acid and alkali treatment and high-temperature activation in the whole process, is only subjected to physical mixing, and keeps a complete pore structure of activated carbon. And the preparation process is simple and high in feasibility.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment in the steel industry, specifically to a method for preparing a chemically modified activated carbon composite adsorbent and its application in the efficient removal of COD from high-salt coking wastewater. Background Technology

[0002] High-salinity wastewater from steel enterprises mainly originates from coal-to-coke, coal gas purification, and chemical product recovery processes. It contains residual ammonia water (containing phenols, cyanides, ammonia nitrogen, etc.) and flue gas desulfurization wastewater. The concentrated brine produced after biochemical treatment and membrane separation (such as reverse osmosis) has a salinity of 5-15%. Coking high-salinity wastewater is characterized by high salinity, high toxicity, high COD, and complex composition. Activated carbon adsorption of COD from high-salinity wastewater presents the following problems: 1. Competitive adsorption: High concentrations of Cl- and SO2- compress the double electric layer of activated carbon, occupying micropore sites and reducing the adsorption capacity for organic matter (experiments show that when salinity >5%, COD removal rate decreases by 40-60%); 2. Shielding effect: Salt ions coat the surface of activated carbon, hindering the diffusion and adsorption of hydrophobic organic matter (such as phenols and oils); 3. Pore clogging: Coking wastewater contains tar-like macromolecules, which easily clog the micropores of activated carbon (pore size 0.5-5nm), leading to a decrease in specific surface area of ​​>30% after regeneration. 4. Chemical Corrosion: Cyanide (CN-) reacts with the functional groups on the surface of activated carbon, destroying the stability of the carbon skeleton. Furthermore, subsequent activated carbon regeneration is difficult and costly. In high-salt environments, organic matter binds tightly to activated carbon, and conventional water washing regeneration efficiency is <50%. Organic solvents (such as methanol-water solution) or strong alkalis (5% NaOH) are required, but the latter easily causes activated carbon loss (weight loss >15% after 5 regenerations).

[0003] Patent No. CN202110891754.0 discloses a COD removal process for high-salt wastewater, which uses the Fenton process to decompose large organic molecules into small molecules, which are then adsorbed by activated carbon. However, the pH needs to be adjusted to 3-4, and the amount of H2O2 added is high.

[0004] In their article "An Investigation into the Removal of Organic Matter from High-Salinity Wastewater by Coal-Based Activated Carbon," Li Ruining et al. used high-salt wastewater from coal chemical industry as the research object and employed coal-based activated carbon adsorption to remove organic matter from the wastewater. Under static adsorption conditions, the COD removal rate of activated carbon for high-salt wastewater from coal chemical industry was 44%. Under dynamic adsorption conditions of a flow rate of 2 BV / h, a temperature of 20℃, and a pH of 5, the removal rate was only 22.8%.

[0005] Existing technologies commonly employ activated carbon adsorption coupled with advanced oxidation processes, but these processes are complex, often requiring multi-stage pH adjustments, solid-liquid separation, and the generation of secondary pollutants. Traditional activated carbon faces dual technical bottlenecks in treating high-salt coking wastewater: salt inhibition and cyanide poisoning. Single modification methods often address one issue at the expense of the other, failing to solve both problems simultaneously.

[0006] Therefore, it is of great significance to develop an activated carbon adsorbent suitable for the efficient removal of COD from high-salt coking wastewater. Summary of the Invention

[0007] Therefore, the technical problem to be solved by this invention is to develop a method for preparing a chemically modified activated carbon composite adsorbent, addressing the characteristics of high salinity and high toxicity in coking wastewater from steel enterprises. Another technical problem to be solved by this invention is to provide an application of this adsorbent for the efficient removal of COD from high-salt coking wastewater.

[0008] The technical solution of this invention is a non-modified composite adsorbent for coking wastewater, comprising the following components: 55-65 wt% activated carbon, 25-30 wt% polystyrene microspheres, and 10-15 wt% montmorillonite; wherein the activated carbon is plant-based activated carbon with a specific surface area ≥1000 m². 2 / g, iodine value ≥900mg / g; the polystyrene microspheres are intrinsic polystyrene with a crosslinking degree of 30-50%. The adsorbent has not been treated with any chemical modifiers.

[0009] According to the present invention, a non-modified composite adsorbent for coking wastewater preferably has a cation exchange capacity (CEC) of 90-139 mmol / 100g for the montmorillonite.

[0010] To achieve the aforementioned CEC value, the montmorillonite may be, for example, organo-montmorillonite modified with hexadecyltrimethylammonium bromide (CTAB), such as the brand Andesu™. Alternatively, it may be natural sodium bentonite with a montmorillonite content greater than 90%, including high-quality montmorillonite from Inner Mongolia, with a CEC of 90-139 mmol / 100g. The montmorillonite is preferably an organo-exfoliated type.

[0011] Furthermore, the modified montmorillonite is an organic exfoliated type with a cation exchange capacity ≥90 mmol / kg; the high-purity sodium-based bentonite has an ion exchange capacity ≥90 mmol / kg.

[0012] According to the present invention, a non-modified composite adsorbent for coking wastewater preferably comprises activated carbon selected from coconut shell activated carbon. The coconut shell activated carbon has an ash content ≤5% and a specific surface area ≥1000 m². 2 / g, iodine value ≥900mg / g.

[0013] According to the present invention, a non-modified composite adsorbent for coking wastewater preferably has a crosslinking degree of 38-42% for the polystyrene microspheres and a particle size of 20-30 μm.

[0014] This invention also provides a method for preparing the above-mentioned unmodified composite adsorbent for coking wastewater, comprising the following steps:

[0015] Step 1, Raw material pretreatment: Crush activated carbon to 60-120 mesh, grind montmorillonite through a 200-500 mesh sieve;

[0016] Step 2: Weigh out activated carbon, polystyrene microspheres, and montmorillonite according to the proportions and place them in a ball mill jar;

[0017] Step 3: Mix by ball milling for 2-5 hours under an inert atmosphere of nitrogen or argon, at a ball milling speed of 200-350 rpm;

[0018] Step 4: After ball milling, the product is washed multiple times and then vacuum dried at 40-70℃ to obtain the finished adsorbent.

[0019] During vacuum drying, the vacuum environment prevents the degradation reaction of PS microsphere polymers, ensuring the integrity of the microsphere structure, while promoting the removal of water from the montmorillonite interlayer and improving ion exchange capacity.

[0020] The preferred solution is:

[0021] Step 1, Raw material pretreatment: Crush activated carbon to 80-100 mesh, grind montmorillonite through a 200-400 mesh sieve;

[0022] Step 2: Weigh out activated carbon, polystyrene microspheres, and montmorillonite according to the proportions and place them in a ball mill jar;

[0023] Step 3: Mix by ball milling for 3-4 hours under an inert atmosphere of nitrogen or argon, at a ball milling speed of 250-300 rpm;

[0024] Step 4: After ball milling, wash the product multiple times, and then vacuum dry at 50-60℃ to obtain the finished adsorbent.

[0025] According to a method for preparing an unmodified composite adsorbent for coking wastewater according to the present invention, preferably, in step 3, the inert atmosphere is nitrogen; the ball milling uses zirconia balls, and the material-to-ball ratio is 1:8-1:10.

[0026] According to a method for preparing an unmodified composite adsorbent for coking wastewater according to the present invention, preferably, in step 4, the washing method is ultrasonic washing with anhydrous ethanol; the vacuum drying in step 4 is performed with a vacuum degree of 0.01 MPa-0.2 MPa and a vacuum drying time of 4-6 hours.

[0027] This invention also provides an application of chemically modified activated carbon composite adsorbent in the efficient removal of COD from high-salt coking wastewater.

[0028] In the above applications, preferably, the method for applying the composite adsorbent to COD in high-salt coking wastewater includes:

[0029] Step 1: Take wastewater and add an appropriate amount of composite adsorbent; the ratio of composite adsorbent to wastewater is 0.5-3g / 100ml.

[0030] Step 2: Adsorption by shaking at 20-30℃ for 2-6 hours;

[0031] Step 3: Filter the solution using a filter membrane and take the clear liquid to test its COD, phenol, and cyanide content.

[0032] After adsorption treatment, the high-salt coking wastewater from step 1 contains: 3% ≤ NaCl ≤ 12%, CN - ≥5 mg / L, phenols ≥100 mg / L. The filter membrane described in step 3 is preferably 0.1-1 μm.

[0033] In the above applications, preferably, in step 2, the dosage of the composite adsorbent is determined according to the COD content. Generally, when the COD in the wastewater is ≤1500mg / L, the dosage of the composite adsorbent is 0.5-1.2g / 100ml; when the COD content in the wastewater is 1500-3000mg / L, the dosage of the composite adsorbent is 1.3-1.8g / 100ml; and when the COD content in the wastewater is ≥3000mg / L, the dosage of the composite adsorbent is 1.9-3g / 100ml.

[0034] Modified montmorillonite primarily serves to shield against salt content in high-salt coking wastewater and alleviate cyanide poisoning. 2+ Mg 2+ ) and Cl - SO4 2- Ion exchange occurs, reducing the ionic strength of the solution and relieving the salt inhibition problem caused by activated carbon adsorption. Modified montmorillonite interlayer cations Fe 3+ With CN - A stable complex is formed, thereby fixing cyanide in wastewater and relieving activated carbon cyanide poisoning.

[0035] In high-salinity wastewater, polystyrene microspheres utilize hydrophobic groups as the primary adsorption driving force. The styrene units within the PS microspheres provide a nonpolar surface, capturing hydrophobic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and phenols through hydrophobic interactions. Activated carbon micropores, after overcoming salt inhibition and cyanide poisoning, can enhance the adsorption capacity for organic matter.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] 1. Breakthrough in both salt resistance and toxin resistance

[0038] Montmorillonite preferentially adsorbs CN - This technology addresses the problem of cyanide poisoning. Montmorillonite's shielding effect against salt ions solves the problem of salt interference from activated carbon, which adsorbs large organic molecules. PS microspheres, due to their hydrophobic properties, show less influence on phenol adsorption in high-salt environments.

[0039] 2. Simplified process

[0040] The adsorbent undergoes no chemical modification, requires no acid or alkali treatment, and is not activated at high temperatures; it is only physically mixed, thus maintaining the intact pore structure of the activated carbon. The preparation process is simple and highly feasible. The adsorbent does not introduce other metal ions, and therefore will not cause pollution during wastewater treatment. Through the synergistic effect of the physically compounded components, it achieves efficient treatment of high-salt wastewater while maintaining the natural structure of activated carbon, providing a low-energy, chemical-free, and green pathway for coking wastewater treatment.

[0041] This invention creates a triple synergistic effect through physical compounding: the ion shielding effect of montmorillonite relieves salt inhibition, the cyanide fixation effect eliminates the risk of poisoning, the hydrophobic adsorption effect of PS microspheres removes phenolic pollutants in a targeted manner, and the activated carbon fully utilizes its microporous adsorption advantages after the inhibition is relieved, achieving a technical effect of 1+1+1>3. Detailed Implementation

[0042] The present invention will be further described below with reference to specific embodiments.

[0043] Comparative Example 1

[0044] The raw materials for preparing activated carbon adsorbent are as follows:

[0045] Components Specifications quality Coconut shell activated carbon <![CDATA[Specific surface area 1100 m 2 / g, iodine value 90 mg / g]]> 55g

[0046] The preparation steps of activated carbon composite adsorbent are as follows:

[0047] Step 1, Preprocessing:

[0048] Activated carbon is crushed and passed through a 70-mesh sieve;

[0049] Step 2, physical compounding:

[0050] Place activated carbon in a ball mill jar; add zirconia balls (material-to-ball ratio 1:8, diameter 5mm).

[0051] Step 3, ball milling compounding:

[0052] Under nitrogen protection, ball mill at 350 rpm for 3 hours (oxygen concentration <0.1%).

[0053] Step 4, Post-processing:

[0054] The adsorbent was ultrasonically washed three times (10 min each time) with anhydrous ethanol and then vacuum dried at 45°C for 4 hours to obtain a black powder adsorbent.

[0055] The prepared adsorbent was used for COD removal from high-salt coking wastewater. The high-salt coking wastewater used was taken from coking wastewater produced by a steel plant, and its water quality had the following characteristics:

[0056] parameter numerical values COD 2050mg / L Salinity (NaCl) 8% phenol 182mg / L Cyanide (CN⁻) 9.8 mg / L pH 7.2

[0057] The adsorption process of the adsorbent for high-salinity wastewater is as follows:

[0058] Step 1: Take 500mL of wastewater and add 7.5g of composite adsorbent (dosage 1.5g / 100mL).

[0059] Step 2: Adsorption was carried out at 25°C and 120 rpm for 4 hours by shaking.

[0060] Step 3: Filter the solution using a 0.45 μm filter membrane, and then analyze the COD, phenol, and cyanide content of the supernatant. The results of the adsorption treatment are as follows:

[0061] index Before treatment (mg / L) After treatment (mg / L) Removal rate COD 2050 1392 32.1% cyanide 9.8 7.3 25.6% phenol 182 106.47 41.5%

[0062] Comparative Example 2

[0063] The raw materials and formulations for the preparation of activated carbon composite adsorbents are as follows:

[0064] Components Specifications quality Coconut shell activated carbon Iodine value ≥900mg / g, particle size 100 mesh 63g Polystyrene microspheres Crosslinking degree 32%, particle size 20-30μm 27g

[0065] The preparation steps of activated carbon composite adsorbent are as follows:

[0066] Step 1, Preprocessing:

[0067] Activated carbon is crushed and passed through a 110-mesh sieve;

[0068] Step 2, physical compounding:

[0069] Place activated carbon and PS microspheres in a ball mill jar; add zirconia balls (material-to-ball ratio 1:10, diameter 5mm).

[0070] Step 3, ball milling compounding:

[0071] Ball milling at 300 pm for 5 hours under nitrogen protection (oxygen concentration <0.1%).

[0072] Step 4, Post-processing:

[0073] The adsorbent was ultrasonically washed three times with anhydrous ethanol (10 min each time); then vacuum dried at 65℃ for 4 hours to obtain a gray-black powder adsorbent.

[0074] The prepared composite adsorbent was used for COD removal from high-salt coking wastewater. The high-salt coking wastewater used was taken from coking wastewater generated by a steel plant, and its water quality had the following characteristics:

[0075] parameter numerical values COD 2050mg / L Salinity (NaCl) 8% phenol 182mg / L Cyanide (CN⁻) 9.8 mg / L pH 7.2

[0076] The adsorption process of the adsorbent for high-salinity wastewater is as follows:

[0077] Step 1: Take 500mL of wastewater and add 7.5g of composite adsorbent (dosage 1.5g / 100mL).

[0078] Step 2: Adsorption was carried out at 25°C and 120 rpm for 4 hours by shaking.

[0079] Step 3: Filter the solution using a 0.45 μm filter membrane, and then analyze the COD, phenol, and cyanide content of the supernatant. The results of the adsorption treatment are as follows:

[0080] index Before treatment (mg / L) After treatment (mg / L) Removal rate COD 2050 1103 46.2% cyanide 9.8 7.0 28.5% phenol 182 26.03 85.7%

[0081] Example 3

[0082] The raw materials and formulations for the preparation of activated carbon composite adsorbents are as follows:

[0083] Components Specifications quality Coconut shell activated carbon Iodine value ≥900mg / g, particle size 100 mesh 60g Polystyrene microspheres Crosslinking degree 40%, particle size 20-30μm 28g Modified montmorillonite Cation exchange capacity ≥90 mmol / kg (Andesu) 12g

[0084] The preparation steps of activated carbon composite adsorbent are as follows:

[0085] Step 1, Preprocessing:

[0086] Activated carbon was crushed and passed through a 100-mesh sieve; modified montmorillonite was ground and passed through a 300-mesh sieve.

[0087] Step 2, physical compounding:

[0088] Place activated carbon, PS microspheres, and modified montmorillonite in a ball mill jar; add zirconia balls (material-to-ball ratio 1:10, diameter 5mm).

[0089] Step 3, ball milling compounding:

[0090] Under nitrogen protection, ball milling was performed at 270 rpm for 3.5 hours (oxygen concentration <0.1%).

[0091] Step 4, Post-processing:

[0092] The adsorbent was ultrasonically washed three times with anhydrous ethanol (10 min each time); then vacuum dried at 55℃ for 5 hours to obtain a gray-black powder adsorbent.

[0093] The prepared composite adsorbent was used for COD removal from high-salt coking wastewater. The high-salt coking wastewater used was taken from coking wastewater generated by a steel plant, and its water quality had the following characteristics:

[0094] parameter numerical values COD 2050mg / L Salinity (NaCl) 8% phenol 182mg / L Cyanide (CN⁻) 9.8 mg / L pH 7.2

[0095] The adsorption process of the adsorbent for high-salinity wastewater is as follows:

[0096] Step 1: Take 500mL of wastewater and add 7.5g of composite adsorbent (dosage 1.5g / 100mL).

[0097] Step 2: Adsorption was carried out at 25°C and 120 rpm for 4 hours by shaking.

[0098] Step 3: Filter the solution using a 0.45 μm filter membrane, and then analyze the COD, phenol, and cyanide content of the supernatant. The results of the adsorption treatment are as follows:

[0099] index Before treatment (mg / L) After treatment (mg / L) Removal rate COD 2050 438 78.6% cyanide 9.8 1.3 86.7% phenol 182 8.74 95.2%

[0100] Comparative Example 1: Single activated carbon achieved removal rates of only 32.1% for COD and 41.5% for phenol in high-salinity wastewater. Comparative Example 2: The two-component formulation showed improved COD and phenol removal rates compared to single activated carbon, reaching 46.2% and 85.7%, respectively, representing increases of 14.1% and 44.2%. PS microspheres, due to their hydrophobic properties, showed less influence from salinity on phenol adsorption in high-salinity environments. Therefore, the addition of PS microspheres significantly improved phenol removal, thereby enhancing COD removal. The three-component formulation in Example 1 achieved COD and phenol removal efficiencies of 78.6% and 95.2%, respectively, representing further improvements of 32.4% and 9.5% compared to the two-component formulation. The addition of montmorillonite further shielded against salt ions, improving the removal of CN... - It also has an adsorption and fixation effect.

[0101] Example 2

[0102] Configure high-salinity coking wastewater with different salinity

[0103] Add 187.5ml, 500ml, and 500ml of high-salt coking wastewater from a steel plant to beakers 1, 2, and 3, respectively. Add deionized water to beaker 1 to a volume of 500ml, and add 20g of food-grade sodium chloride to beaker 3.

[0104] The high-salt coking wastewater used was taken from coking wastewater produced by a steel plant, and its water quality has the following characteristics:

[0105] parameter numerical values COD 2050mg / L Salinity (NaCl) 8% phenol 182mg / L Cyanide (CN⁻) 9.8 mg / L pH 7.2

[0106] The wastewater salinities in the three beakers after preparation were 3%, 8%, and 12%, respectively. The adsorbent prepared in the example was used to adsorb the high-salt wastewater, and the operation was as follows:

[0107] Step 1: Take 500mL of wastewater and add 7.5g of composite adsorbent;

[0108] Step 2: Adsorption was carried out at 25°C and 120 rpm for 4 hours by shaking.

[0109] Step 3: Filter the solution using a 0.45 μm filter membrane, and analyze the COD, phenol, and cyanide content of the supernatant. The indicators after adsorption treatment are as follows:

[0110] serial number salinity Before treatment (mg / L) After treatment (mg / L) COD removal rate 1 3% NaCl 780 664.56 85.20% 2 8% NaCl 2050 1566.2 76.40% 3 12% NaCl 2030 1483.93 73.10%

[0111] As the salinity gradually increased in the three beakers, the activated carbon composite adsorbent showed high COD removal capacity within the salinity range of 3%-12%, with a COD removal efficiency ≥73.10%. This demonstrates the shielding effect of PS microspheres and montmorillonite on salt ions, especially the shielding effect of montmorillonite.

[0112] Example 3

[0113] The raw materials and formulations for the preparation of activated carbon composite adsorbents are as follows:

[0114] Components Specifications quality Coconut shell activated carbon Iodine value ≥950mg / g, particle size 100 mesh 65g Polystyrene microspheres Crosslinking degree 40%, particle size 20-30μm 25g Modified montmorillonite Cation exchange capacity ≥110 mmol / kg (Andesu) 10g

[0115] The preparation steps of activated carbon composite adsorbent are as follows:

[0116] Step 1, Preprocessing:

[0117] Activated carbon was crushed and passed through a 100-mesh sieve; modified montmorillonite was ground and passed through a 300-mesh sieve.

[0118] Step 2, physical compounding:

[0119] Place activated carbon, PS microspheres, and modified montmorillonite in a ball mill jar; add zirconia balls (material-to-ball ratio 1:10, diameter 5mm).

[0120] Step 3, ball milling compounding:

[0121] Under nitrogen protection, ball mill at 270 rpm for 3 hours (oxygen concentration <0.1%).

[0122] Step 4, Post-processing:

[0123] The adsorbent was ultrasonically washed three times with anhydrous ethanol (10 min each time); then vacuum dried at 60℃ for 3 hours to obtain a gray-black powder adsorbent.

[0124] The prepared composite adsorbent was used for COD removal from high-salt coking wastewater. The high-salt coking wastewater used was taken from coking wastewater generated by a steel plant, and its water quality had the following characteristics:

[0125] parameter numerical values COD 2050mg / L Salinity (NaCl) 8% phenol 182mg / L Cyanide (CN⁻) 9.8 mg / L pH 7.2

[0126] The adsorption process of the adsorbent for high-salinity wastewater is as follows:

[0127] Step 1: Take 500mL of wastewater and add 7.5g of composite adsorbent (dosage 1.5g / 100mL).

[0128] Step 2: Adsorption was carried out at 25°C and 120 rpm for 4 hours by shaking.

[0129] Step 3: Filter the solution using a 0.45 μm filter membrane, and then analyze the COD, phenol, and cyanide content of the supernatant. The results of the adsorption treatment are as follows:

[0130] index Before treatment (mg / L) After treatment (mg / L) Removal rate COD 2050 451 78.0% cyanide 9.8 1.2 87.8% phenol 182 9.8 94.6%

[0131] Example 4

[0132] The raw materials and formulations for the preparation of activated carbon composite adsorbents are as follows:

[0133] Components Specifications quality Coconut shell activated carbon Iodine value ≥1000mg / g, particle size 100 mesh 58g Polystyrene microspheres Crosslinking degree 45%, particle size 20-30μm 30g Modified montmorillonite Cation exchange capacity ≥110 mmol / kg (Andesu) 12g

[0134] The preparation steps of activated carbon composite adsorbent are as follows:

[0135] Step 1, Preprocessing:

[0136] Activated carbon was crushed and passed through a 100-mesh sieve; modified montmorillonite was ground and passed through a 300-mesh sieve.

[0137] Step 2, physical compounding:

[0138] Place activated carbon, PS microspheres, and modified montmorillonite in a ball mill jar; add zirconia balls (material-to-ball ratio 1:10, diameter 5mm).

[0139] Step 3, ball milling compounding:

[0140] Under nitrogen protection, ball mill at 270 rpm for 3 hours (oxygen concentration <0.1%).

[0141] Step 4, Post-processing:

[0142] The adsorbent was ultrasonically washed three times with anhydrous ethanol (10 min each time); then vacuum dried at 60℃ for 3 hours to obtain a gray-black powder adsorbent.

[0143] The prepared composite adsorbent was used for COD removal from high-salt coking wastewater. The high-salt coking wastewater used was taken from coking wastewater generated by a steel plant, and its water quality had the following characteristics:

[0144] parameter numerical values COD 3250mg / L Salinity (NaCl) 10% phenol 280mg / L Cyanide (CN⁻) 15.2 mg / L pH 7.5

[0145] The adsorption process of the adsorbent for high-salinity wastewater is as follows:

[0146] Step 1: Take 500 mL of wastewater and add 10.0 g of composite adsorbent (dosage 2.0 g / 100 mL).

[0147] Step 2: Adsorption was carried out at 25°C and 120 rpm for 4 hours by shaking.

[0148] Step 3: Filter the solution using a 0.45 μm filter membrane, and then analyze the COD, phenol, and cyanide content of the supernatant. The results of the adsorption treatment are as follows:

[0149] index Before treatment (mg / L) After treatment (mg / L) Removal rate COD 3250 832 784.4% cyanide 15.2 2.1 86.2% phenol 280 16.8 94.0%

[0150] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art will recognize that the formulation and preparation process of the present invention can be modified and varied in various ways. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A non-modified composite adsorbent for coking wastewater, characterized by: The active carbon is plant-based active carbon, specific surface area is greater than or equal to 1000 m 2 / g, iodine value is greater than or equal to 90 mg / g; the polystyrene microspheres are intrinsic state polystyrene, crosslinking degree is 30-50%.

2. A non-modified composite adsorbent for coking wastewater according to claim 1, characterized by: The cation exchange capacity (CEC) of the montmorillonite is 90-139 mmol / 100g.

3. A non-modified composite adsorbent for coking wastewater according to claim 2, characterized in that: The cation exchange capacity (CEC) of the montmorillonite is 115-139 mmol / 100g; the montmorillonite comprises montmorillonite and natural sodium-based bentonite with a montmorillonite content of more than 90%.

4. The non-modified composite adsorbent for coking wastewater according to claim 1, characterized by: The activated carbon is selected from coconut shell activated carbon.

5. The non-modified composite adsorbent for coking wastewater according to claim 1, characterized by: The cross-linking degree of the polystyrene microspheres is 38-42%, and the particle size of the polystyrene microspheres is 20-30 μm.

6. The method for preparing an unmodified composite adsorbent for coking wastewater according to claim 1, characterized in that: The method comprises the following steps: Step 1, raw material pretreatment: the activated carbon is crushed to 60-120 mesh, and the montmorillonite is ground to pass through a 200-500 mesh sieve; Step 2, the activated carbon, polystyrene microspheres and montmorillonite are weighed according to the proportion and placed in a ball mill tank; Step 3, the mixture is ball-milled under a nitrogen or argon inert atmosphere for 2-5 hours, and the ball-milling rotation speed is 200-350 rpm; Step 4, after the ball-milling is completed, the product is washed multiple times, and then vacuum dried at 40-70°C to obtain a finished adsorbent.

7. The method for preparing a non-modified composite adsorbent for coking wastewater according to claim 6, characterized in that: In step 3, the inert atmosphere is nitrogen; the ball-milling uses zirconia balls, and the ratio of material to ball is 1:8-1:

10.

8. The method for preparing an unmodified composite adsorbent for coking wastewater according to claim 6, characterized in that: In step 4, the washing method is ultrasonic washing with anhydrous ethanol; the vacuum drying in step 4 is performed at a vacuum degree of 0.01 Mpa-0.2 Mpa; and the vacuum drying time is 4-6 h.

9. Application of the chemically unmodified activated carbon composite adsorbent of claim 1 in efficient removal of COD in high-salt coking wastewater.

10. Use according to claim 9, characterized in that: The application method of the composite adsorbent in COD in high-salt coking wastewater comprises: Step 1, taking wastewater, and adding an appropriate amount of composite adsorbent; the ratio of the composite adsorbent to the wastewater is 0.5-3 g / 100 ml; Step 2, oscillating adsorption at 20-30°C for 2-6 h; Step 3, using a filter membrane to perform suction filtration, and detecting the COD, phenol and cyanide content of the clear liquid.

11. Use according to claim 9, characterized in that: In step 2, the composite adsorbent dosage is determined according to the COD content; generally, when the COD content in the wastewater is ≤1500 mg / L, the composite adsorbent dosage is 0.5-1.2 g / 100 ml; when the COD content in the wastewater is 1500-3000 mg / L, the composite adsorbent dosage is 1.3-1.8 g / 100 ml; and when the COD content in the wastewater is ≥3000 mg / L, the composite adsorbent dosage is 1.9-3 g / 100 ml.