A method for synergistically treating petrochemical wastewater based on porous carbon and micro-nano bubbles

Abstract

The present application relates to the technical field of wastewater treatment, and particularly relates to a method for treating petrochemical wastewater based on cooperation of porous carbon and micro-nano bubbles, comprising the following steps: S1, pretreating petrochemical wastewater; S2, performing micro-nano aeration on the pretreated petrochemical wastewater by using a micro-nano bubble generating device to obtain aerated wastewater; and S3, performing adsorption treatment on the aerated wastewater by using modified porous carbon to obtain purified wastewater, wherein the modified porous carbon is biomass porous carbon loaded with ammonium rhodanate. The present application realizes efficient removal of multiple types of pollutants (including refractory organic matter, heavy metals and suspended particulate matter) by using the cooperative treatment process of pretreatment, micro-nano bubble oxidation and modified porous carbon adsorption, improves the wastewater treatment efficiency, and reduces the operation cost.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles. Background Technology

[0002] Petrochemical wastewater is characterized by its complex composition, high organic content, and high biotoxicity, making it difficult to treat and potentially causing serious water pollution if not treated properly. Currently, the main treatment methods for petrochemical wastewater include physicochemical methods, biological methods, and advanced treatment technologies. Traditional physicochemical treatment methods rely primarily on adding large amounts of chemical agents for flocculation and sedimentation. While this can remove some pollutants, it suffers from high treatment costs and a high risk of secondary pollution. Biological methods, although effective to some extent, are limited by the high content of recalcitrant organic matter and high biotoxicity in petrochemical wastewater, resulting in less than ideal treatment outcomes.

[0003] Biochar has attracted widespread attention in the field of water pollution control due to its well-developed pore structure, high specific surface area, and abundant surface functional groups. However, in the treatment of petrochemical wastewater, the use of biochar alone has the following shortcomings: First, biochar has a limited adsorption capacity and is prone to adsorption saturation; second, biochar prepared from different raw materials has significant differences in properties, affecting the stability of treatment effects; and third, the surface functional groups of biochar are of a single type, resulting in insufficient selective adsorption capacity for certain specific pollutants.

[0004] Existing patent CN201510018160.3 discloses a process for treating oil and gas drilling wastewater, including the following steps: (1) collecting wastewater; (2) flocculation and sedimentation: the wastewater in the equalization tank flows through an integrated dosing machine and passes through NaOH and XH in sequence. -2 XH -3 XH -4 Its function is to maintain the pH value of the water at the outlet of the integrated dosing machine at 6-9, causing flocculation and sedimentation in the wastewater; among which, NaOH and XH -2 XH -3 XH -4 The concentrations were 10%, 20%, 20%, and 0.15%, respectively; (3) quartz sand filtration; (4) activated carbon filtration; (5) precision filter filtration; (6) ultrafiltration separation; (7) reverse osmosis separation. This process can effectively remove small molecule compounds, high molecular polymers, and Clˉ, reduce COD and BOD values, and make the treated liquid clear and transparent. However, the above technical solutions have the following disadvantages: (1) the adsorption capacity of activated carbon is limited and it is easy to become saturated; at the same time, the functional group type of activated carbon surface is single, and its selective adsorption capacity for certain specific pollutants is insufficient; (2) the process flow is complex and requires multiple treatment units, including flocculation sedimentation, multi-stage filtration and membrane separation, which increases energy consumption and operating costs. Summary of the Invention

[0005] In view of this, the present invention proposes a method for the synergistic treatment of petrochemical wastewater based on porous carbon and micro-nano bubbles, in order to solve the problems of unsatisfactory pollutant removal effect and complex treatment process in the prior art.

[0006] The technical solution of this invention is achieved as follows: This invention provides a method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles, comprising the following steps:

[0007] S1. Pre-treat petrochemical wastewater;

[0008] S2. Micro-nano bubble generator is used to aerate the pretreated petrochemical wastewater to obtain aerated wastewater.

[0009] S3. The aerated wastewater is subjected to adsorption treatment with modified porous carbon to obtain purified wastewater. The modified porous carbon is biomass porous carbon loaded with rose red tricarboxylic acid ammonium.

[0010] This invention establishes a complete petrochemical wastewater treatment system through the synergistic effect of pretreatment, micro / nano bubble oxidation, and modified porous carbon adsorption. Pretreatment effectively removes suspended solids, oils, and some heavy metal ions from the petrochemical wastewater. Micro / nano bubbles effectively degrade macromolecular organic matter in the wastewater. Modified porous carbon selectively adsorbs specific pollutants, deeply removing residual organic matter and heavy metal ions. These three steps are interconnected and mutually reinforcing, improving treatment efficiency while reducing operating costs. Furthermore, this invention fully utilizes waste biomass to prepare modified porous carbon, reducing the use of chemical agents and demonstrating good environmental friendliness and economic benefits.

[0011] Based on the above technical solutions, preferably, in step S1, the pretreatment specifically includes: treating the petrochemical wastewater with oil separation, then adding a softener and a composite flocculant to the petrochemical wastewater after oil separation, stirring thoroughly, allowing it to settle, and filtering to obtain the pretreated petrochemical wastewater.

[0012] Based on the above technical solutions, preferably, the softening agent is one or more of calcium hydroxide, sodium hydroxide, and sodium carbonate; the composite flocculant is composed of polyaluminum ferric chloride, polyacrylamide, and polyzirconium chloride in a mass ratio of 2:1:0.5-0.7; and the amount of composite flocculant added is 45-55 mg per liter of petrochemical wastewater.

[0013] The pretreatment process adopts a three-stage treatment process of "oil separation-softening-flocculation". First, oil separation is used to remove free oil and large particulate suspended solids from petrochemical wastewater, reducing the load on subsequent treatment. Then, a softener is added to remove calcium and magnesium ions from the water to prevent scaling during subsequent treatment, while adjusting the pH value of the wastewater to a suitable range. Finally, the composite flocculant is used to achieve efficient removal of residual suspended solids, colloidal particles and some dissolved pollutants from the wastewater.

[0014] In the composite flocculant, polyaluminum ferric chloride effectively reduces the potential of colloidal particles through charge neutralization, promoting particle aggregation; polyacrylamide connects unstable colloidal particles through adsorption bridging, forming large flocs; and polyzirconium chloride, due to its unique tetravalent zirconium ions with stronger charge density and hydrolytic ability, further enhances the density and stability of the flocs. The synergistic effect of the three components improves flocculation efficiency, resulting in dense flocs with rapid settling and good treatment effect.

[0015] Based on the above technical solutions, preferably, in step S2, the pressure inside the micro-nano bubble generator is 2-5 bar, the gas introduced into the micro-nano bubble generator is any one of air, oxygen and ozone, the diameter of the micro-nano bubbles is 200-400 nm, and the micro-nano aeration time is 2-3 h.

[0016] Micro- and nanobubbles are tiny bubbles with diameters between the micro and nanometer scale. They rise slowly in water, have a long residence time, and possess a large specific surface area, increasing the contact area between the gas and the solution. When the gas-liquid interface collapses and disappears during the ascent of micro- and nanobubbles, the high concentration of charged ions that had accumulated at the gas-liquid interface immediately release chemical energy, generating hydroxyl radicals that can oxidize and decompose organic pollutants. Furthermore, this eliminates the need for large-scale chemical additions during wastewater treatment, avoiding secondary pollution. This invention incorporates micro- and nanobubble treatment before activated carbon adsorption. Through the oxidation effect of micro- and nanobubbles, large organic molecules are degraded into smaller molecules that are more easily adsorbed, reducing the adsorption load on the modified porous carbon and extending the adsorbent's lifespan.

[0017] Based on the above technical solutions, the preferred method for preparing the modified porous carbon is as follows:

[0018] (1) Biomass raw materials and activators are mixed and then activated and carbonized to obtain primary activated carbon;

[0019] (2) Add primary activated carbon to a mixed solution of thiourea and melamine, ultrasonically disperse for 30-40 min, and heat at 100-120℃ for 6-8 h to obtain activated carbon precursor; place the porous carbon precursor in a tube furnace and carbonize it under an inert atmosphere to obtain sulfur and nitrogen co-doped porous carbon.

[0020] (3) Disperse sulfur-nitrogen co-doped porous carbon in 3% H2O2 solution and stir at room temperature for 0.5-1h to obtain activated sulfur-nitrogen co-doped porous carbon; add activated sulfur-nitrogen co-doped porous carbon to a mixed solution of toluene and 3-aminopropyltriethoxysilane, ultrasonically disperse for 15-20min, reflux and stir at 80℃ for 4-6h, filter, wash and dry to obtain aminated modified porous carbon;

[0021] (4) Disperse the aminated porous carbon in a methanol / water mixture, add rose red tricarboxylic acid ammonium, ultrasonically disperse for 10-15 min, add dilute hydrochloric acid to adjust the pH to 5-6, stir the reaction at 50-60℃ for 4-6 h, filter, wash and dry to obtain modified porous carbon.

[0022] In step (1), primary activated carbon with microporous and mesoporous structures is prepared by mixing and activating carbonization with activator and biomass raw materials; in step (2), thiourea and melamine are used as doping sources, and sulfur and nitrogen elements are co-doped by ultrasonic dispersion and heat treatment to improve the surface activity of activated carbon and enhance its affinity for polar pollutants; in step (3), amino groups are introduced on the surface of sulfur and nitrogen co-doped porous carbon by silane coupling agent to provide reaction sites for subsequent functionalization modification; in step (4), the amino groups on the surface of aminated porous carbon react with the ketone groups in red tricarboxylic acid ammonium to achieve loading of red tricarboxylic acid ammonium. The synergistic effect of multiple functional groups such as carboxyl, hydroxyl, and amino groups in red tricarboxylic acid ammonium further enhances the treatment effect of modified porous carbon on various pollutants in petrochemical wastewater. In addition, the covalent bond has higher stability, effectively avoiding the loss of functional molecules during wastewater treatment and ensuring the long-term performance of modified porous carbon.

[0023] Based on the above technical solutions, preferably, step (1) specifically includes:

[0024] Biomass raw materials and potassium hydroxide are mixed at a mass ratio of 1:2.5-3, heated to 410-430℃ under a nitrogen atmosphere, and reacted for 30-40 minutes. The activated product is then acid-washed, water-washed, dried, pulverized, and sieved to obtain primary activated carbon.

[0025] Based on the above technical solutions, the preferred biomass raw materials are at least one of tree branches, corn stalks, wheat stalks, rice stalks, coconut shells, and fruit shells.

[0026] Based on the above technical solutions, preferably, in step (2), the mass ratio of primary porous carbon, thiourea and melamine is 1:1.5-2:1, the carbonization temperature is 550-600℃, and the carbonization time is 1-2h.

[0027] Based on the above technical solutions, preferably, in step (3), the mass ratio of sulfur-nitrogen co-doped porous carbon and 3-aminopropyltriethoxysilane is 1:0.5-1, and the mass ratio of 3-aminopropyltriethoxysilane and toluene is 1:20-30.

[0028] Based on the above technical solutions, preferably, in step (4), the mass ratio of aminated porous carbon to rose red tricarboxylic acid ammonium is 1:0.5-0.8; and the concentration of the dilute hydrochloric acid is 1-2 mol / L.

[0029] Based on the above technical solutions, preferably, in step S3, the aerated wastewater and modified porous carbon are mixed at a mass ratio of 80-120:1.

[0030] The method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro / nano bubbles in this invention has the following advantages over existing technologies:

[0031] (1) Through the synergistic treatment process of pretreatment, micro-nano bubble oxidation and modified porous carbon adsorption, the efficient removal of multiple types of pollutants (including recalcitrant organic matter, heavy metals and suspended particulate matter) can be achieved, thereby improving wastewater treatment efficiency and reducing operating costs. Among them, pretreatment effectively removes suspended solids, oily substances and some heavy metal ions from petrochemical wastewater, micro-nano bubbles can effectively degrade macromolecular organic matter in petrochemical wastewater and reduce the load of subsequent adsorption treatment, and the selective adsorption of modified porous carbon on specific pollutants can deeply remove residual organic matter and heavy metal ions in wastewater.

[0032] (2) The pretreatment stage adopts a three-stage pretreatment process of "oil separation-softening-flocculation" and uses a composite flocculant composed of polyaluminum ferric chloride, polyacrylamide and polyzirconium chloride. Through the synergistic effect of charge neutralization, bridging and enhanced flocculation, the density and settling performance of the flocs are significantly improved.

[0033] (3) Petrochemical wastewater is pretreated by oxidation using a micro-nano bubble generator. The extremely high specific surface area and stability of micro-nano bubbles, combined with the hydroxyl radicals generated during bubble rupture, achieve the initial degradation of macromolecular pollutants and the enrichment of some pollutants in the wastewater. Compared with traditional oxidation methods, the micro-nano bubble treatment process can significantly improve the biodegradability of pollutants without the need for additional chemical oxidants. At the same time, it reduces the burden on subsequent adsorption units and extends the life of adsorbents, demonstrating the advantages of high efficiency and green treatment.

[0034] (4) By activating and carbonizing biomass raw materials, co-doping with sulfur and nitrogen and surface functionalization, the porous structure of modified porous carbon and the rich multifunctional groups (such as carboxyl, phenolic hydroxyl and amino groups) on its surface endow it with high selective adsorption performance for organic and inorganic pollutants, enabling modified activated carbon to deeply remove residual organic pollutants and heavy metal ions in petrochemical wastewater; at the same time, it has higher stability through covalent bonding, further ensuring the long-term performance of modified porous carbon. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a flowchart of the method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles according to the present invention. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1

[0039] like Figure 1 As shown, this embodiment discloses a method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles, including the following steps:

[0040] S1. The petrochemical wastewater is first treated by oil separation in a horizontal flow oil separator for 1 hour at a temperature of 25°C. Then, a 10% sodium hydroxide solution is added to the oil-separated petrochemical wastewater to adjust the pH to 8.0-8.5. Next, 50 mg / L of composite flocculant is added. The composite flocculant is made by compounding polyaluminum ferric chloride, polyacrylamide, and polyzirconium chloride in a mass ratio of 2:1:0.6. The mixture is thoroughly stirred using a mechanical stirrer at 200 r / min for 2 minutes and 60 r / min for 10 minutes. After settling for 30 minutes, the pretreated petrochemical wastewater is obtained by filtration.

[0041] S2. Micro-nano bubble generator is used to aerate the pretreated petrochemical wastewater. The pressure inside the micro-nano bubble generator is set to 3.5 bar, ozone concentration of 50 mg / L is introduced, gas flow rate is 2.0 L / min, and the diameter of the generated micro-nano bubbles is controlled to be 300 nm. Micro-nano aeration is carried out at room temperature for 2.5 h to obtain aerated wastewater.

[0042] S3. The aerated wastewater and modified porous carbon are mixed at a mass ratio of 100:1 and stirred at 120 r / min for 3 hours at 25℃ for adsorption treatment. The purified wastewater is then obtained by filtration.

[0043] The preparation method of modified porous carbon is as follows:

[0044] (1) 100g of biomass raw material (corn straw and wheat straw in a mass ratio of 1:1) was crushed and passed through a 60-mesh sieve, mixed evenly with 280g of potassium hydroxide, placed in a tube furnace, heated to 420℃ in a nitrogen atmosphere at a heating rate of 5℃ / min, reacted for 35min, and then naturally cooled to room temperature. The activated product was then acid washed, water washed, dried, crushed and sieved to obtain primary activated carbon.

[0045] (2) Dissolve 180g of thiourea and 60g of melamine in 1000nl of deionized water to form a mixed solution. Add 100g of primary activated carbon to the mixed solution, ultrasonically disperse for 35min, heat to 110℃ for 7h, filter and dry to obtain activated carbon precursor. Place the porous carbon precursor in a tube furnace and heat to 580℃ at a heating rate of 5℃ / min under an inert atmosphere for 1.5h carbonization treatment. Allow to cool naturally to room temperature to obtain sulfur and nitrogen co-doped porous carbon.

[0046] (3) 100g of sulfur-nitrogen co-doped porous carbon was dispersed in 1000ml of 3% H2O2 solution and stirred at room temperature for 0.8h. After filtration, washing and drying, activated sulfur-nitrogen co-doped porous carbon was obtained. The activated sulfur-nitrogen co-doped porous carbon was added to a mixed solution of 200g toluene and 80g 3-aminopropyltriethoxysilane, ultrasonically dispersed for 18min, refluxed and stirred at 80℃ for 5h, and then filtered, washed and dried to obtain aminated modified porous carbon.

[0047] (4) Disperse 100g of aminated porous carbon in 1000ml of methanol / water (volume ratio 3:1), add 65g of rose red tricarboxylic acid ammonium, sonicate for 13min, add dilute hydrochloric acid to adjust pH to 5-6, stir and react at 55℃ for 5h, filter, wash and dry to obtain modified porous carbon.

[0048] Example 2

[0049] This embodiment discloses a method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles, including the following steps:

[0050] S1. The petrochemical wastewater is first treated by oil separation in a horizontal flow oil separator for 1 hour at a temperature of 25°C. Then, a 10% sodium hydroxide solution is added to the oil-separated petrochemical wastewater to adjust the pH to 8.0-8.5. Next, 45 mg / L of composite flocculant is added. The composite flocculant is made by compounding polyaluminum ferric chloride, polyacrylamide, and polyzirconium chloride in a mass ratio of 2:1:0.5. The mixture is thoroughly stirred using a mechanical stirrer at 200 r / min for 2 minutes and 60 r / min for 10 minutes. After settling for 30 minutes, the pretreated petrochemical wastewater is obtained by filtration.

[0051] S2. Micro-nano bubble generator is used to aerate the pretreated petrochemical wastewater. The pressure inside the micro-nano bubble generator is set to 2 bar, ozone concentration is 45 mg / L, gas flow rate is 1.5 L / min, and the diameter of the generated micro-nano bubbles is controlled to be 200 nm. Micro-nano aeration is carried out at room temperature for 2 hours to obtain aerated wastewater.

[0052] S3. The aerated wastewater and modified porous carbon are mixed at a mass ratio of 80:1 and stirred at 120 r / min for 3 hours at 25℃ for adsorption treatment. The purified wastewater is then obtained by filtration.

[0053] The preparation method of modified porous carbon is as follows:

[0054] (1) 100g of biomass raw material (corn straw and wheat straw in a mass ratio of 1:1) was crushed and passed through a 60-mesh sieve, mixed evenly with 250g of potassium hydroxide, placed in a tube furnace, heated to 410℃ in a nitrogen atmosphere at a heating rate of 5℃ / min, reacted for 40min, and then naturally cooled to room temperature. The activated product was then acid washed, water washed, dried, crushed and sieved to obtain primary activated carbon.

[0055] (2) Dissolve 150g of thiourea and 60g of melamine in 1000nl of deionized water to form a mixed solution. Add 100g of primary activated carbon to the mixed solution, ultrasonically disperse for 30min, heat to 100℃ for 8h, filter and dry to obtain activated carbon precursor. Place the porous carbon precursor in a tube furnace and heat to 550℃ for 2h at a heating rate of 5℃ / min under an inert atmosphere. Cool naturally to room temperature to obtain sulfur and nitrogen co-doped porous carbon.

[0056] (3) 100g of sulfur-nitrogen co-doped porous carbon was dispersed in 1000ml of 3% H2O2 solution and stirred at room temperature for 0.5h. After filtration, washing and drying, activated sulfur-nitrogen co-doped porous carbon was obtained. The activated sulfur-nitrogen co-doped porous carbon was added to a mixed solution of 100g toluene and 50g 3-aminopropyltriethoxysilane, ultrasonically dispersed for 15min, refluxed and stirred at 70℃ for 6h, and after filtration, washing and drying, aminated modified porous carbon was obtained.

[0057] (4) Disperse 100g of aminated porous carbon in 1000ml of methanol / water (volume ratio 3:1), add 50g of rose red tricarboxylic acid ammonium, sonicate for 10min, add dilute hydrochloric acid to adjust pH to 5-6, stir and react at 50℃ for 6h, filter, wash and dry to obtain modified porous carbon.

[0058] Example 3

[0059] This embodiment discloses a method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles, including the following steps:

[0060] S1. The petrochemical wastewater is first treated by oil separation in a horizontal flow oil separator for 1 hour at a temperature of 25°C. Then, a 10% sodium hydroxide solution is added to the oil-separated petrochemical wastewater to adjust the pH to 8.0-8.5. 55 mg / L of composite flocculant is then added, which is a mixture of polyaluminum ferric chloride, polyacrylamide, and polyzirconium chloride in a mass ratio of 2:1:0.7. The mixture is thoroughly stirred using a mechanical stirrer at 200 r / min for 2 minutes and 60 r / min for 10 minutes. After settling for 30 minutes, the pretreated petrochemical wastewater is obtained by filtration.

[0061] S2. Micro-nano bubble generator was used to aerate the pretreated petrochemical wastewater. The pressure inside the micro-nano bubble generator was set to 5 bar, ozone with a concentration of 55 mg / L was introduced, the gas flow rate was 2.5 L / min, and the diameter of the generated micro-nano bubbles was controlled to be 400 nm. The micro-nano aeration treatment was carried out at room temperature for 3 hours to obtain the aerated wastewater.

[0062] S3. The aerated wastewater and modified porous carbon are mixed at a mass ratio of 120:1 and stirred at 120 r / min for 3 hours at 25℃ for adsorption treatment. The purified wastewater is then obtained by filtration.

[0063] The preparation method of modified porous carbon is as follows:

[0064] (1) 100g of biomass raw material (corn straw and wheat straw in a mass ratio of 1:1) was crushed and passed through a 60-mesh sieve, mixed evenly with 300g of potassium hydroxide, placed in a tube furnace, heated to 430℃ in a nitrogen atmosphere at a heating rate of 5℃ / min, reacted for 30min, and then naturally cooled to room temperature. The activated product was then acid washed, water washed, dried, crushed and sieved to obtain primary activated carbon.

[0065] (2) Dissolve 200g of thiourea and 60g of melamine in 1000nl of deionized water to form a mixed solution. Add 100g of primary activated carbon to the mixed solution, ultrasonically disperse for 40min, heat to 120℃ for 6h, filter and dry to obtain activated carbon precursor; place the porous carbon precursor in a tube furnace, heat to 600℃ at a heating rate of 5℃ / min under an inert atmosphere for 1h carbonization treatment, and naturally cool to room temperature to obtain sulfur and nitrogen co-doped porous carbon.

[0066] (3) 100g of sulfur-nitrogen co-doped porous carbon was dispersed in 1000ml of 3% H2O2 solution and stirred at room temperature for 1h. After filtration, washing and drying, activated sulfur-nitrogen co-doped porous carbon was obtained. The activated sulfur-nitrogen co-doped porous carbon was added to a mixed solution of 300g toluene and 100g 3-aminopropyltriethoxysilane, ultrasonically dispersed for 20min, refluxed and stirred at 90℃ for 4h, and then filtered, washed and dried to obtain aminated modified porous carbon.

[0067] (4) Disperse 100g of aminated porous carbon in 1000ml of methanol / water (volume ratio 3:1), add 80g of rose red tricarboxylic acid ammonium, sonicate for 15min, add dilute hydrochloric acid to adjust pH to 5-6, stir and react at 60℃ for 4h, filter, wash and dry to obtain modified porous carbon.

[0068] Comparative Example 1

[0069] This comparative example discloses a method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles, including the following steps:

[0070] Steps S1-S3 are the same as in Example 1, except that:

[0071] The preparation method of modified porous carbon is as follows:

[0072] (1) 100g of biomass raw material (corn straw and wheat straw in a mass ratio of 1:1) was crushed and passed through a 60-mesh sieve, mixed evenly with 280g of potassium hydroxide, placed in a tube furnace, heated to 420℃ in a nitrogen atmosphere at a heating rate of 5℃ / min, reacted for 35min, and then naturally cooled to room temperature. The activated product was then acid washed, water washed, dried, crushed and sieved to obtain primary activated carbon.

[0073] (2) Dissolve 180g of thiourea and 60g of melamine in 1000nl of deionized water to form a mixed solution. Add 100g of primary activated carbon to the mixed solution, ultrasonically disperse for 35min, heat to 110℃ for 7h, filter and dry to obtain activated carbon precursor. Place the porous carbon precursor in a tube furnace and heat to 580℃ at a heating rate of 5℃ / min under an inert atmosphere for 1.5h carbonization treatment. Allow to cool naturally to room temperature to obtain sulfur and nitrogen co-doped porous carbon.

[0074] (3) 100g of sulfur-nitrogen co-doped porous carbon was dispersed in 1000ml of 3% H2O2 solution and stirred at room temperature for 0.8h. After filtration, washing and drying, activated sulfur-nitrogen co-doped porous carbon was obtained. The activated sulfur-nitrogen co-doped porous carbon was added to a mixed solution of 200g toluene and 80g 3-aminopropyltriethoxysilane, ultrasonically dispersed for 18min, refluxed and stirred at 80℃ for 5h, and after filtration, washing and drying, modified porous carbon was obtained.

[0075] Comparative Example 2

[0076] This comparative example discloses a method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles, including the following steps:

[0077] Steps S1-S3 are the same as in Example 1, except that:

[0078] The preparation method of modified porous carbon is as follows:

[0079] (1) 100g of biomass raw material (corn straw and wheat straw in a mass ratio of 1:1) was crushed and passed through a 60-mesh sieve, mixed evenly with 280g of potassium hydroxide, placed in a tube furnace, heated to 420℃ in a nitrogen atmosphere at a heating rate of 5℃ / min, reacted for 35min, and then naturally cooled to room temperature. The activated product was then acid washed, water washed, dried, crushed and sieved to obtain primary activated carbon.

[0080] (2) 100g of primary activated carbon was dispersed in 1000ml of 3% H2O2 solution and stirred at room temperature for 0.8h. After filtration, washing and drying, activated porous carbon was obtained. The activated porous carbon was added to a mixed solution of 200g toluene and 80g 3-aminopropyltriethoxysilane, ultrasonically dispersed for 18min, refluxed and stirred at 80℃ for 5h, and after filtration, washing and drying, aminated modified porous carbon was obtained.

[0081] (3) Disperse 100g of aminated porous carbon in 1000ml of methanol / water (volume ratio 3:1), add 65g of rose red tricarboxylic acid ammonium, sonicate for 13min, add dilute hydrochloric acid to adjust pH to 5-6, stir and react at 55℃ for 5h, filter, wash and dry to obtain modified porous carbon.

[0082] Comparative Example 3

[0083] This comparative example discloses a method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles, including the following steps:

[0084] S1. The petrochemical wastewater is first treated by oil separation in a horizontal flow oil separator for 1 hour at a temperature of 25°C. Then, a 10% sodium hydroxide solution is added to the oil-separated petrochemical wastewater to adjust the pH to 8.0-8.5. Next, 50 mg / L of composite flocculant is added. The composite flocculant is made by compounding polyaluminum ferric chloride and polyacrylamide in a mass ratio of 2:1. The mixture is thoroughly stirred using a mechanical stirrer at 200 r / min for 2 minutes and 60 r / min for 10 minutes. After settling for 30 minutes, the pretreated petrochemical wastewater is obtained by filtration.

[0085] S2. Micro-nano bubble generator is used to aerate the pretreated petrochemical wastewater. The pressure inside the micro-nano bubble generator is set to 3.5 bar, ozone concentration of 50 mg / L is introduced, gas flow rate is 2.0 L / min, and the diameter of the generated micro-nano bubbles is controlled to be 300 nm. Micro-nano aeration is carried out at room temperature for 2.5 h to obtain aerated wastewater.

[0086] S3. The aerated wastewater and modified porous carbon are mixed at a mass ratio of 100:1 and stirred at 120 r / min for 3 hours at 25°C for adsorption treatment. The purified wastewater is then obtained by filtration. The modified porous carbon is prepared in the same way as in Example 1.

[0087] Comparative Example 4

[0088] This embodiment discloses a method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles, including the following steps:

[0089] S1. The petrochemical wastewater is first treated by oil separation in a horizontal flow oil separator for 1 hour at a temperature of 25°C. Then, a 10% sodium hydroxide solution is added to the oil-separated petrochemical wastewater to adjust the pH to 8.0-8.5. Next, 50 mg / L of composite flocculant is added. The composite flocculant is made by compounding polyaluminum ferric chloride, polyacrylamide, and polyzirconium chloride in a mass ratio of 2:1:0.6. The mixture is thoroughly stirred using a mechanical stirrer at 200 r / min for 2 minutes and 60 r / min for 10 minutes. After settling for 30 minutes, the pretreated petrochemical wastewater is obtained by filtration.

[0090] S2. The pretreated petrochemical wastewater and modified porous carbon are mixed at a mass ratio of 100:1 and stirred at 120 r / min for 3 h at 25 °C for adsorption treatment. The adsorbed wastewater is then obtained by filtration. The modified porous carbon preparation method is the same as in Example 1.

[0091] S3. A micro-nano bubble generator was used to aerate the adsorbed wastewater. The pressure inside the micro-nano bubble generator was set to 3.5 bar, ozone with a concentration of 50 mg / L was introduced, the gas flow rate was 2.0 L / min, and the diameter of the generated micro-nano bubbles was controlled to be 300 nm. The micro-nano aeration treatment was carried out at room temperature for 2.5 h to obtain the purified wastewater.

[0092] Performance testing

[0093] Wastewater from the examples and comparative cases after purification treatment was collected. The content of heavy metal ions in the petrochemical wastewater before and after purification treatment was detected, and the heavy metal ion removal rate was calculated. The heavy metal ions included chromium ions, lead ions, and mercury ions. The COD content in the petrochemical wastewater before and after purification treatment was detected using a TE-3001 Tianer portable COD analyzer, and the COD removal rate was calculated. The mineral oil content in the petrochemical wastewater before and after purification treatment was detected using ultraviolet spectrophotometry, and the mineral oil removal rate was calculated. The test results are shown in Table 1.

[0094] Table 1

[0095]

[0096] As shown in Table 1, the technical solution of the present invention has a good effect on the treatment of petrochemical wastewater and can significantly improve the removal rate of heavy metal ions, COD and mineral oil.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles, characterized in that: Includes the following steps: S1. Pre-treat petrochemical wastewater; S2. Micro-nano bubble generator is used to aerate the pretreated petrochemical wastewater to obtain aerated wastewater. S3. The aerated wastewater is subjected to adsorption treatment by modified porous carbon to obtain purified wastewater. The modified porous carbon is biomass porous carbon loaded with rose red tricarboxylic acid ammonium. The modified porous carbon is prepared as follows: (1) Biomass raw materials and potassium hydroxide are mixed and activated and carbonized to obtain primary activated carbon; (2) Add primary activated carbon to a mixed solution of thiourea and melamine, ultrasonically disperse for 30-40 min, heat at 100-120℃ for 6-8 h to obtain activated carbon precursor; place the activated carbon precursor in a tube furnace and carbonize it under an inert atmosphere to obtain sulfur and nitrogen co-doped porous carbon. (3) Disperse sulfur-nitrogen co-doped porous carbon in 3% H2O2 solution and stir at room temperature for 0.5-1h to obtain activated sulfur-nitrogen co-doped porous carbon; add activated sulfur-nitrogen co-doped porous carbon to a mixed solution of toluene and 3-aminopropyltriethoxysilane, ultrasonically disperse for 15-20min, reflux and stir at 70-90℃ for 4-6h, filter, wash and dry to obtain aminated porous carbon; (4) Disperse the aminated porous carbon in a methanol / water mixture, add rose red tricarboxylic acid ammonium, ultrasonically disperse for 10-15 min, add dilute hydrochloric acid to adjust the pH to 5-6, stir the reaction at 50-60℃ for 4-6 h, filter, wash and dry to obtain modified porous carbon.

2. The method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles as described in claim 1, characterized in that: In step S1, the pretreatment specifically includes: treating the petrochemical wastewater with oil separation, then adding a softener and a composite flocculant to the oil-separated petrochemical wastewater, stirring thoroughly, allowing it to settle, and filtering to obtain the pretreated petrochemical wastewater.

3. The method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles as described in claim 2, characterized in that: The softening agent is one or more of calcium hydroxide, sodium hydroxide, and sodium carbonate; the composite flocculant is composed of polyaluminum ferric chloride, polyacrylamide, and polyzirconium chloride in a mass ratio of 2:1:0.5-0.

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4. The method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles as described in claim 1, characterized in that: In step S2, the pressure inside the micro-nano bubble generator is 2-5 bar, the gas introduced into the micro-nano bubble generator is any one of air, oxygen and ozone, the diameter of the micro-nano bubbles is 200-400 nm, and the micro-nano aeration time is 2-3 h.

5. The method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles as described in claim 1, characterized in that: Step (1) specifically includes: Biomass raw materials and potassium hydroxide are mixed at a mass ratio of 1:2.5-3, heated to 410-430℃ under a nitrogen atmosphere, and reacted for 30-40 minutes. The activated product is then acid-washed, water-washed, dried, pulverized, and sieved to obtain primary activated carbon.

6. The method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles as described in claim 1, characterized in that: Biomass raw materials include at least one of tree branches, corn stalks, wheat stalks, rice stalks, coconut shells, and fruit shells.

7. The method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles as described in claim 1, characterized in that: In step (2), the mass ratio of primary activated carbon, thiourea, and melamine is 1:1.5-2:0.6, the carbonization temperature is 550-600℃, and the carbonization time is 1-2h.

8. The method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles as described in claim 1, characterized in that: In step (3), the mass ratio of sulfur-nitrogen co-doped porous carbon to 3-aminopropyltriethoxysilane is 1:0.5-1, and the mass ratio of 3-aminopropyltriethoxysilane to toluene is 1:20-30.

9. The method for synergistic treatment of petrochemical wastewater based on porous carbon and micro / nano bubbles as described in claim 1, characterized in that: In step (4), the mass ratio of aminated porous carbon to rose red tricarboxylic acid ammonium is 1:0.5-0.8; the concentration of the dilute hydrochloric acid is 1-2 mol / L.

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