Method for cooperatively treating petrochemical wastewater based on porous carbon and micro-nano bubbles

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a method for cooperatively treating petrochemical wastewater based on porous carbon and micro-nano bubbles, which comprises the following steps: S1, pretreating the petrochemical wastewater; s2, carrying out micro-nano aeration on the pretreated petrochemical wastewater by adopting a micro-nano bubble generation device to obtain aerated wastewater; s3, the aerated wastewater is subjected to adsorption treatment through modified porous carbon, purified wastewater is obtained, and the modified porous carbon is biomass porous carbon loaded with rose red ammonium tricarboxylate. According to the invention, through a cooperative treatment process of pretreatment, micro-nano bubble oxidation and modified porous carbon adsorption, efficient removal of multiple types of pollutants (including refractory organic matters, heavy metals and suspended particulate matters) is realized, the wastewater treatment efficiency is improved, and the operation cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles. Background Art

[0002] Petrochemical wastewater has the characteristics of complex composition, high organic content, and high biological toxicity. It is difficult to treat. If it is not treated properly, it will cause serious pollution to the water environment. At present, the treatment methods of petrochemical wastewater mainly include physicochemical method, biological method and deep treatment technology. Traditional physicochemical treatment methods mainly rely on the addition of a large amount of chemical agents for flocculation and precipitation. Although it can remove some pollutants, there are problems such as high treatment cost and easy secondary pollution. Although the biological method has a certain treatment effect, it is limited by the high content of difficult-to-degrade organic matter and high biological toxicity in petrochemical wastewater, and the treatment effect is not ideal.

[0003] Biochar has attracted extensive attention in the field of water pollution control due to its well-developed pore structure, high specific surface area, and rich surface functional groups. However, in the treatment of petrochemical wastewater, the use of biochar alone has the following shortcomings: first, the adsorption capacity of biochar is limited and it is easy to be saturated; second, the properties of biochar prepared from different raw materials vary greatly, which affects the stability of the treatment effect; third, the type of functional groups on the surface of biochar is single, and the selective adsorption capacity for certain specific pollutants is insufficient.

[0004] The existing patent CN201510018160.3 discloses a process for treating oil and gas drilling wastewater, which includes the following steps: (1) collecting wastewater; (2) flocculation and sedimentation: the wastewater in the regulating tank flows through an integrated dosing machine and passes through NaOH, XH -2 , XH -3 , XH -4 The pH value of the water at the outlet of the integrated dosing machine is 6-9, and the wastewater produces flocculation and precipitation; among them, NaOH, XH -2 , XH -3 , XH -4 The concentrations are 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 molecular 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 be saturated; at the same time, the type of functional groups on the surface of activated carbon is single, and the selective adsorption capacity for certain specific pollutants is insufficient; (2) The process flow is complicated and needs to go through 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 treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles to solve the problems of unsatisfactory removal of pollutants in petrochemical wastewater and complex treatment process in the prior art.

[0006] The technical solution of the present invention is implemented as follows: The present invention provides a method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles, comprising the following steps:

[0007] S1. Pre-treating petrochemical wastewater;

[0008] S2, using a micro-nano bubble generator to perform micro-nano aeration on the pretreated petrochemical wastewater to obtain aerated wastewater;

[0009] S3. The aerated wastewater is subjected to adsorption treatment by modified porous carbon to obtain purified wastewater, wherein the modified porous carbon is a biomass porous carbon loaded with rose red ammonium tricarboxylate.

[0010] The present invention forms a complete petrochemical wastewater treatment system through the synergistic effects of pretreatment, micro-nano bubble oxidation and modified porous carbon adsorption. Among them, the pretreatment is to effectively remove suspended matter, oil substances and some heavy metal ions in petrochemical wastewater, the micro-nano bubbles can effectively degrade the macromolecular organic matter in petrochemical wastewater, and the selective adsorption of modified porous carbon on specific pollutants can deeply remove the residual organic matter and heavy metal ions in the wastewater. The three steps are connected and promote each other, which not only improves the treatment efficiency but also reduces the operating cost. At the same time, the present invention makes full use of waste biomass to prepare modified porous carbon, reduces the use of chemical agents, and has good environmental friendliness and economic benefits.

[0011] On the basis of the above technical scheme, preferably, in step S1, the pretreatment specifically includes: subjecting the petrochemical wastewater to oil separation treatment, then adding a softener and a composite flocculant to the oil-separated petrochemical wastewater, fully stirring, allowing to settle, and filtering to obtain the pretreated petrochemical wastewater.

[0012] On the basis of the above technical scheme, preferably, the softener 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; the addition amount of the composite flocculant 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, free oil and large suspended particles in petrochemical wastewater are removed through oil separation treatment to reduce the subsequent treatment load; then softeners are added to remove calcium and magnesium ions in the water to prevent scaling during subsequent treatment, and the pH value of the wastewater is adjusted to an appropriate range; finally, the effect of composite flocculants is used to achieve efficient removal of residual suspended matter, colloidal particles and some soluble pollutants in the wastewater.

[0014] Among the composite flocculants, polyaluminium chloride ferric can effectively reduce the potential of colloidal particles through electrical neutralization and promote particle aggregation; polyacrylamide connects unstable colloidal particles through adsorption bridging to form large flocs; polyzirconium chloride, due to its unique tetravalent zirconium ion, has a stronger charge density and hydrolysis ability, which can further enhance the density and stability of flocs. The synergistic effect of the three components can improve the flocculation efficiency, and the flocs formed have a dense structure, fast sedimentation rate, and good treatment effect.

[0015] On the basis of the above technical scheme, preferably, in step S2, the pressure in the micro-nano bubble generating device is 2-5 bar, the gas introduced into the micro-nano bubble generating device 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-nano bubbles are tiny bubbles with diameters between the micro-nano level. They rise slowly in water, have a long residence time, and have a large specific surface area, which increases the contact area between the gas and the solution. When the gas-liquid interface of the micro-nano bubbles collapses and disappears during the rising process, the high-concentration charged ions originally gathered on the gas-liquid interface will immediately release chemical energy, thereby generating hydroxyl radicals, which can oxidize and decompose organic pollutants. At the same time, when treating wastewater, a large amount of reagents do not need to be added, thus avoiding secondary pollution. The present invention arranges micro-nano bubble treatment before activated carbon adsorption treatment, and degrades macromolecular organic matter into small molecular substances that are easier to adsorb through the oxidation of micro-nano bubbles, thereby reducing the adsorption load of the modified porous carbon and extending the service life of the adsorbent.

[0017] On the basis of the above technical solution, preferably, the preparation method of the modified porous carbon is as follows:

[0018] (1) mixing a biomass raw material and an activating agent, and subjecting them to activation and carbonization treatment to obtain primary activated carbon;

[0019] (2) adding primary activated carbon to a mixed solution of thiourea and melamine, ultrasonically dispersing for 30-40 minutes, and heating at 100-120° C. for 6-8 hours to obtain an activated carbon precursor; placing the porous carbon precursor in a tubular furnace and carbonizing it under an inert atmosphere to obtain sulfur-nitrogen co-doped porous carbon;

[0020] (3) dispersing sulfur-nitrogen co-doped porous carbon in a 3% H2O2 solution, stirring the reaction at room temperature for 0.5-1h to obtain activated sulfur-nitrogen co-doped porous carbon; adding the activated sulfur-nitrogen co-doped porous carbon to a mixed solution of toluene and 3-aminopropyltriethoxysilane, ultrasonically dispersing for 15-20min, stirring under reflux at 80°C for 4-6h, filtering, washing, and drying to obtain amino-modified porous carbon;

[0021] (4) The aminated porous carbon is dispersed in a mixed solution of methanol / water, and rose red ammonium tricarboxylate is added, and ultrasonic dispersion is performed for 10-15 minutes. Dilute hydrochloric acid is added to adjust the pH to 5-6, and the reaction is stirred at 50-60° C. for 4-6 hours. After filtering, washing, and drying, the modified porous carbon is obtained.

[0022] In step (1), primary activated carbon with microporous and mesoporous structures is prepared by mixing an activator and a biomass raw material for activation and carbonization; in step (2), thiourea and melamine are used as doping sources, and co-doping of sulfur and nitrogen elements is achieved through ultrasonic dispersion and heat treatment, thereby improving the surface activity of activated carbon and enhancing its affinity for polar pollutants; in step (3), amino groups are introduced on the surface of sulfur-nitrogen co-doped porous carbon through a silane coupling agent to provide reaction sites for subsequent functional modification; in step (4), the loading of rose-red ammonium tricarboxylate is achieved by reacting the amino groups on the surface of the aminated porous carbon with the ketone groups in rose-red ammonium tricarboxylate, and the synergistic effects of the carboxyl, hydroxyl, amino and other multi-functional groups in the rose-red ammonium tricarboxylate further enhance the treatment effect of the modified porous carbon on various pollutants in petrochemical wastewater. In addition, the covalent bond has higher stability, which effectively avoids the shedding of functional molecules during wastewater treatment and ensures the long-term performance of the modified porous carbon;

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

[0024] The biomass raw material and potassium hydroxide are mixed in a mass ratio of 1:2.5-3, heated to 410-430°C under a nitrogen atmosphere, reacted for 30-40 minutes, and then the activated product is acid-washed, washed with water, dried, crushed, and sieved to obtain primary activated carbon.

[0025] On the basis of the above technical solution, preferably, the biomass raw material is at least one of tree branches, corn stalks, wheat stalks, rice stalks, coconut shells and fruit shells.

[0026] On the basis of the above technical solution, preferably, in step (2), the mass ratio of primary porous carbon, thiourea and melamine is 1:1.5-2:1, the temperature of carbonization treatment is 550-600°C, and the time of carbonization treatment is 1-2h.

[0027] On the basis of the above technical solution, preferably, 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.

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

[0029] On the basis of the above technical solution, preferably, in step S3, the aerated wastewater is mixed with the modified porous carbon in a mass ratio of 80-120:1.

[0030] The method of treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles of the present invention has the following beneficial effects compared with the prior art:

[0031] (1) Through the synergistic treatment process of pretreatment, micro-nano bubble oxidation and modified porous carbon adsorption, efficient removal of multiple types of pollutants (including refractory organic matter, heavy metals and suspended particulate matter) is achieved, wastewater treatment efficiency is improved, and operating costs are reduced; among them, pretreatment is to effectively remove suspended matter, oil substances and some heavy metal ions in petrochemical wastewater, micro-nano bubbles can effectively degrade macromolecular organic matter in petrochemical wastewater and reduce the subsequent adsorption treatment load, 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) In the pretreatment stage, a three-stage pretreatment process of "oil separation-softening-flocculation" was adopted, and a composite flocculant composed of polyaluminum ferric chloride, polyacrylamide and polyzirconium chloride was used. Through the synergistic effects of electrical neutralization, bridging and enhanced flocculation, the density and sedimentation performance of the flocs were significantly improved;

[0033] (3) The petrochemical wastewater is pre-oxidized by 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 the bubble rupture process, achieve the initial degradation of macromolecular pollutants in the wastewater and the enrichment of some pollutants. 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, while reducing the burden on subsequent adsorption units and extending the life of the adsorbent, reflecting the advantages of efficient and green treatment.

[0034] (4) By subjecting biomass raw materials to activated carbonization, sulfur-nitrogen co-doping and surface functionalization modification, the porous structure of the modified porous carbon and the rich multi-functional groups on its surface (such as carboxyl, phenolic hydroxyl and amino groups) are used to give it highly selective adsorption properties for organic and inorganic pollutants, enabling the 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 bond bonding, further ensuring the long-term performance of the modified porous carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 This is a flow chart of the method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles of the present invention;. DETAILED DESCRIPTION

[0037] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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 treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles, comprising the following steps:

[0040] S1. First, the petrochemical wastewater is subjected to oil separation treatment by passing through a horizontal flow oil separator, with a residence time of 1 hour and 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, and then 50 mg / L of a composite flocculant is added, wherein the composite flocculant is prepared by compounding polyaluminum ferric chloride, polyacrylamide and polyzirconium chloride in a mass ratio of 2:1:0.6, and the mixture is fully stirred and stirred by a mechanical stirrer, with a rapid stirring speed of 200 r / min for 2 minutes, a slow stirring speed of 60 r / min for 10 minutes, and the mixture is allowed to settle for 30 minutes, and filtered to obtain the pretreated petrochemical wastewater;

[0041] S2. The pretreated petrochemical wastewater was subjected to micro-nano aeration using a micro-nano bubble generator, the pressure in 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, the diameter of the generated micro-nano bubbles was controlled to be 300 nm, and the micro-nano aeration treatment was performed at room temperature for 2.5 h to obtain aerated wastewater;

[0042] S3. The aerated wastewater was mixed with the modified porous carbon at a mass ratio of 100:1, stirred at a speed of 120 r / min for 3 h at 25° C. for adsorption treatment, and then filtered to obtain purified wastewater.

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

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

[0045] (2) 180 g of thiourea and 60 g of melamine were dissolved in 1000 nl of deionized water to form a mixed solution, 100 g of primary activated carbon was added to the mixed solution, ultrasonically dispersed for 35 min, heated to 110 ° C for 7 h, filtered and dried to obtain an activated carbon precursor; the porous carbon precursor was placed in a tubular furnace, heated to 580 ° C at a heating rate of 5 ° C / min under an inert atmosphere for carbonization treatment for 1.5 h, and naturally cooled to room temperature to obtain sulfur-nitrogen co-doped porous carbon;

[0046] (3) Dispersing 100 g of sulfur-nitrogen co-doped porous carbon in 1000 ml of 3% H2O2 solution, stirring the reaction at room temperature for 0.8 h, filtering, washing, and drying to obtain activated sulfur-nitrogen co-doped porous carbon; adding the activated sulfur-nitrogen co-doped porous carbon to a mixed solution of 200 g of toluene and 80 g of 3-aminopropyltriethoxysilane, ultrasonically dispersing for 18 min, reflux stirring at 80° C. for 5 h, filtering, washing, and drying to obtain amino-modified porous carbon;

[0047] (4) Disperse 100 g of amino-modified porous carbon in a mixed solution of 1000 ml of methanol / water (volume ratio of 3:1), add 65 g of rose red ammonium tricarboxylate, and ultrasonically disperse for 13 min. Add dilute hydrochloric acid to adjust the pH to 5-6, stir and react at 55 °C for 5 h, filter, wash, and dry to obtain modified porous carbon.

[0048] Example 2

[0049] This embodiment discloses a method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles, comprising the following steps:

[0050] S1. Firstly, the petrochemical wastewater is subjected to oil separation treatment by passing through a horizontal flow oil separator, with a residence time of 1 hour and 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, and then 45 mg / L of a composite flocculant is added, wherein the composite flocculant is prepared by compounding polyaluminum ferric chloride, polyacrylamide and polyzirconium chloride in a mass ratio of 2:1:0.5, and the mixture is fully stirred and stirred by a mechanical stirrer, with a rapid stirring speed of 200 r / min for 2 minutes, a slow stirring speed of 60 r / min for 10 minutes, and the mixture is allowed to settle for 30 minutes, and filtered to obtain the pretreated petrochemical wastewater;

[0051] S2. The pretreated petrochemical wastewater was subjected to micro-nano aeration using a micro-nano bubble generator, the pressure in the micro-nano bubble generator was set to 2 bar, ozone with a concentration of 45 mg / L was introduced, the gas flow rate was 1.5 L / min, the diameter of the generated micro-nano bubbles was controlled to be 200 nm, and the micro-nano aeration treatment was performed at room temperature for 2 h to obtain aerated wastewater;

[0052] S3. The aerated wastewater was mixed with the modified porous carbon in a mass ratio of 80:1, stirred at a speed of 120 r / min for 3 h at 25° C. for adsorption treatment, and then filtered to obtain purified wastewater.

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

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

[0055] (2) 150 g of thiourea and 60 g of melamine were dissolved in 1000 nl of deionized water to form a mixed solution, 100 g of primary activated carbon was added to the mixed solution, ultrasonically dispersed for 30 min, heated to 100 ° C for 8 h, filtered and dried to obtain an activated carbon precursor; the porous carbon precursor was placed in a tubular furnace, heated to 550 ° C at a heating rate of 5 ° C / min under an inert atmosphere for carbonization treatment for 2 h, and naturally cooled to room temperature to obtain sulfur-nitrogen co-doped porous carbon;

[0056] (3) Dispersing 100 g of sulfur-nitrogen co-doped porous carbon in 1000 ml of 3% H2O2 solution, stirring the reaction at room temperature for 0.5 h, filtering, washing, and drying to obtain activated sulfur-nitrogen co-doped porous carbon; adding the activated sulfur-nitrogen co-doped porous carbon to a mixed solution of 100 g of toluene and 50 g of 3-aminopropyltriethoxysilane, ultrasonically dispersing for 15 min, refluxing at 70 ° C. and stirring for 6 h, filtering, washing, and drying to obtain amino-modified porous carbon;

[0057] (4) Disperse 100 g of amino-modified porous carbon in a mixed solution of 1000 ml of methanol / water (volume ratio of 3:1), add 50 g of rose red ammonium tricarboxylate, ultrasonically disperse for 10 min, add dilute hydrochloric acid to adjust the pH to 5-6, stir and react at 50 ° C for 6 h, filter, wash and dry to obtain modified porous carbon.

[0058] Example 3

[0059] This embodiment discloses a method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles, comprising the following steps:

[0060] S1. Firstly, the petrochemical wastewater is subjected to oil separation treatment by passing through a horizontal flow oil separator, with a residence time of 1 hour and 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, and then 55 mg / L of a composite flocculant is added, wherein the composite flocculant is prepared by compounding polyaluminum ferric chloride, polyacrylamide and polyzirconium chloride in a mass ratio of 2:1:0.7, and the mixture is fully stirred and stirred by a mechanical stirrer, with a rapid stirring speed of 200 r / min for 2 minutes, a slow stirring speed of 60 r / min for 10 minutes, and the mixture is allowed to settle for 30 minutes, and filtered to obtain the pretreated petrochemical wastewater;

[0061] S2. The pretreated petrochemical wastewater was subjected to micro-nano aeration using a micro-nano bubble generator, the pressure in 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, the diameter of the generated micro-nano bubbles was controlled to be 400 nm, and the micro-nano aeration treatment was performed at room temperature for 3 h to obtain aerated wastewater;

[0062] S3. The aerated wastewater was mixed with the modified porous carbon in a mass ratio of 120:1, stirred at a speed of 120 r / min for 3 h at 25° C. for adsorption treatment, and then filtered to obtain purified wastewater.

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

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

[0065] (2) 200 g of thiourea and 60 g of melamine were dissolved in 1000 nl of deionized water to form a mixed solution, 100 g of primary activated carbon was added to the mixed solution, ultrasonically dispersed for 40 min, heated to 120 ° C for 6 h, filtered and dried to obtain an activated carbon precursor; the porous carbon precursor was placed in a tubular furnace, heated to 600 ° C at a heating rate of 5 ° C / min in an inert atmosphere for carbonization treatment for 1 h, and naturally cooled to room temperature to obtain sulfur-nitrogen co-doped porous carbon;

[0066] (3) dispersing 100 g of sulfur-nitrogen co-doped porous carbon in 1000 ml of 3% H2O2 solution, stirring the reaction at room temperature for 1 h, filtering, washing, and drying to obtain activated sulfur-nitrogen co-doped porous carbon; adding the activated sulfur-nitrogen co-doped porous carbon to a mixed solution of 300 g of toluene and 100 g of 3-aminopropyltriethoxysilane, ultrasonically dispersing for 20 min, reflux stirring at 90° C. for 4 h, filtering, washing, and drying to obtain amino-modified porous carbon;

[0067] (4) Disperse 100 g of amino-modified porous carbon in a mixed solution of 1000 ml of methanol / water (volume ratio of 3:1), add 80 g of rose red ammonium tricarboxylate, ultrasonically disperse for 15 min, add dilute hydrochloric acid to adjust the pH to 5-6, stir and react at 60 ° C for 4 h, filter, wash and dry to obtain modified porous carbon.

[0068] Comparative Example 1

[0069] This comparative example discloses a method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles, comprising the following steps:

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

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

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

[0073] (2) 180 g of thiourea and 60 g of melamine were dissolved in 1000 nl of deionized water to form a mixed solution, 100 g of primary activated carbon was added to the mixed solution, ultrasonically dispersed for 35 min, heated to 110 ° C for 7 h, filtered and dried to obtain an activated carbon precursor; the porous carbon precursor was placed in a tubular furnace, heated to 580 ° C at a heating rate of 5 ° C / min under an inert atmosphere for carbonization treatment for 1.5 h, and naturally cooled to room temperature to obtain sulfur-nitrogen co-doped porous carbon;

[0074] (3) Dispersing 100 g of sulfur-nitrogen co-doped porous carbon in 1000 ml of 3% H2O2 solution, stirring the reaction at room temperature for 0.8 h, filtering, washing, and drying to obtain activated sulfur-nitrogen co-doped porous carbon; adding the activated sulfur-nitrogen co-doped porous carbon to a mixed solution of 200 g of toluene and 80 g of 3-aminopropyltriethoxysilane, ultrasonically dispersing for 18 min, reflux stirring at 80°C for 5 h, filtering, washing, and drying to obtain modified porous carbon.

[0075] Comparative Example 2

[0076] This comparative example discloses a method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles, comprising the following steps:

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

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

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

[0080] (2) Dispersing 100 g of primary activated carbon in 1000 ml of 3% H2O2 solution, stirring the reaction at room temperature for 0.8 h, filtering, washing, and drying to obtain activated porous carbon; adding the activated porous carbon to a mixed solution of 200 g of toluene and 80 g of 3-aminopropyltriethoxysilane, ultrasonically dispersing for 18 min, reflux stirring at 80° C. for 5 h, filtering, washing, and drying to obtain amino-modified porous carbon;

[0081] (3) Disperse 100 g of amino-modified porous carbon in a mixed solution of 1000 ml of methanol / water (volume ratio of 3:1), add 65 g of rose red ammonium tricarboxylate, and ultrasonically disperse for 13 min. Add dilute hydrochloric acid to adjust the pH to 5-6, stir and react at 55 °C for 5 h, filter, wash and dry to obtain modified porous carbon.

[0082] Comparative Example 3

[0083] This comparative example discloses a method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles, comprising the following steps:

[0084] S1. First, the petrochemical wastewater is subjected to oil separation treatment by passing through a horizontal flow oil separator, with a residence time of 1 hour and a temperature of 25°C; then, a 10% sodium hydroxide solution is added to the petrochemical wastewater after oil separation to adjust the pH to 8.0-8.5, and then 50 mg / L of a composite flocculant is added, wherein the composite flocculant is prepared by compounding polyaluminum ferric chloride and polyacrylamide in a mass ratio of 2:1, and the mixture is fully stirred and stirred by a mechanical stirrer, with a rapid stirring speed of 200 r / min for 2 minutes, a slow stirring speed of 60 r / min for 10 minutes, and the mixture is allowed to settle for 30 minutes, and filtered to obtain the pretreated petrochemical wastewater;

[0085] S2. The pretreated petrochemical wastewater was subjected to micro-nano aeration using a micro-nano bubble generator, the pressure in 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, the diameter of the generated micro-nano bubbles was controlled to be 300 nm, and the micro-nano aeration treatment was performed at room temperature for 2.5 h to obtain aerated wastewater;

[0086] S3. The aerated wastewater and modified porous carbon are mixed in a mass ratio of 100:1, stirred at a speed of 120 r / min for 3 h at 25° C. for adsorption treatment, and then filtered to obtain purified wastewater, wherein the preparation method of the modified porous carbon is the same as that in Example 1.

[0087] Comparative Example 4

[0088] This embodiment discloses a method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles, comprising the following steps:

[0089] S1. First, the petrochemical wastewater is subjected to oil separation treatment by passing through a horizontal flow oil separator, with a residence time of 1 hour and 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, and then 50 mg / L of a composite flocculant is added, wherein the composite flocculant is prepared by compounding polyaluminum ferric chloride, polyacrylamide and polyzirconium chloride in a mass ratio of 2:1:0.6, and the mixture is fully stirred and stirred by a mechanical stirrer, with a rapid stirring speed of 200 r / min for 2 minutes, a slow stirring speed of 60 r / min for 10 minutes, and the mixture is allowed to settle for 30 minutes, and filtered to obtain the pretreated petrochemical wastewater;

[0090] S2, mixing the pretreated petrochemical wastewater with the modified porous carbon in a mass ratio of 100:1, stirring at a speed of 120 r / min for 3 h at 25° C. for adsorption treatment, and then filtering to obtain the adsorbed wastewater. The preparation method of the modified porous carbon is the same as that of Example 1;

[0091] S3. Use a micro-nano bubble generator to perform micro-nano aeration on the adsorbed wastewater. Set the pressure in the micro-nano bubble generator to 3.5 bar, introduce ozone with a concentration of 50 mg / L, and a gas flow rate of 2.0 L / min. Control the diameter of the generated micro-nano bubbles to be 300 nm. Perform micro-nano aeration treatment at room temperature for 2.5 hours to obtain purified wastewater.

[0092] Performance Testing

[0093] Take the wastewater after purification treatment in the embodiment and the comparative example, detect the content of heavy metal ions in the petrochemical wastewater before and after purification treatment, and calculate the removal rate of heavy metal ions, wherein the heavy metal ions include chromium ions, lead ions and mercury ions; use the TE-3001 Tianer Instrument portable COD measuring instrument to detect the COD content in the petrochemical wastewater before and after purification treatment, and calculate the COD removal rate; use ultraviolet spectrophotometry to detect the mineral oil content in the petrochemical wastewater before and after purification treatment, and calculate the mineral oil removal rate. The test results are shown in Table 1.

[0094] Table 1

[0095]

[0096] It can be seen from Table 1 that the technical solution of the present invention has a good treatment effect on 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 in the protection scope of the present invention.

Claims

1. A method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles, characterized in that: The following steps are involved: S1. Pre-treating petrochemical wastewater; S2, using a micro-nano bubble generator to perform micro-nano aeration on 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, wherein the modified porous carbon is a biomass porous carbon loaded with rose red ammonium tricarboxylate.

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

3. A method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles as claimed in claim 2, characterized in that: The softener is one or more of calcium hydroxide, sodium hydroxide and sodium carbonate; the composite flocculant is composed of polyaluminium chloride iron, polyacrylamide and polyzirconium chloride in a mass ratio of 2:1:0.5-0.

7.

4. The method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles as claimed in claim 1, characterized in that: In step S2, the pressure in the micro-nano bubble generating device is 2-5 bar, the gas introduced into the micro-nano bubble generating device 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 treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles as claimed in claim 1, characterized in that: The preparation method of the modified porous carbon is as follows: (1) mixing a biomass raw material and an activating agent, and subjecting them to activation and carbonization treatment to obtain primary activated carbon; (2) adding primary activated carbon to a mixed solution of thiourea and melamine, ultrasonically dispersing for 30-40 minutes, and heating at 100-120° C. for 6-8 hours to obtain an activated carbon precursor; placing the porous carbon precursor in a tubular furnace and carbonizing it under an inert atmosphere to obtain sulfur-nitrogen co-doped porous carbon; (3) dispersing sulfur-nitrogen co-doped porous carbon in a 3% H2O2 solution, stirring the reaction at room temperature for 0.5-1h to obtain activated sulfur-nitrogen co-doped porous carbon; adding the activated sulfur-nitrogen co-doped porous carbon to a mixed solution of toluene and 3-aminopropyltriethoxysilane, ultrasonically dispersing for 15-20min, stirring under reflux at 70-90°C for 4-6h, filtering, washing, and drying to obtain amino-modified porous carbon; (4) The aminated porous carbon is dispersed in a mixed solution of methanol / water, and rose red ammonium tricarboxylate is added, and ultrasonic dispersion is performed for 10-15 minutes. Dilute hydrochloric acid is added to adjust the pH to 5-6, and the reaction is stirred at 50-60° C. for 4-6 hours. After filtering, washing, and drying, the modified porous carbon is obtained.

6. A method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles as claimed in claim 5, characterized in that: Step (1) specifically includes: The biomass raw material and potassium hydroxide are mixed in a mass ratio of 1:2.5-3, heated to 410-430°C under a nitrogen atmosphere, reacted for 30-40 minutes, and then the activated product is acid-washed, washed with water, dried, crushed, and sieved to obtain primary activated carbon.

7. The method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles as claimed in claim 5, characterized in that: The biomass raw material is at least one of tree branches, corn stalks, wheat stalks, rice stalks, coconut shells and fruit shells.

8. The method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles as claimed in claim 5, characterized in that: In step (2), the mass ratio of primary porous carbon, thiourea and melamine is 1:1.5-2:0.6, the temperature of carbonization treatment is 550-600°C, and the time of carbonization treatment is 1-2h.

9. The method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles as claimed in claim 5, 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.

10. The method for treating petrochemical wastewater based on the synergistic effect of porous carbon and micro-nano bubbles as claimed in claim 5, characterized in that: In step (4), the mass ratio of the aminated porous carbon to the rose red ammonium tricarboxylate is 1:0.5-0.8; and the concentration of the dilute hydrochloric acid is 1-2 mol / L.

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