Treatment method for efficiently removing organic matters through solid phase-air floatation coupling

Abstract

The invention relates to the field of water treatment, and particularly discloses a treatment method for efficiently removing organic matters through solid phase-air flotation coupling, which comprises the following steps: S1, adding sodium chloride and a surfactant into wastewater to be treated, and then adding a solid flotation agent; s2, introducing gas into the to-be-treated wastewater to carry out air flotation treatment, separating scum above the wastewater through a filter screen, and removing organic matters in the wastewater; wherein the solid flotation agent in the step S1 is obtained by treating worm graphite serving as a carrier in a mixed solvent of organic amine, a diluent and a solubilizer. The device and the method have the advantage that multi-component high-concentration organic pollutants can be efficiently removed under the strongly acidic condition.

Description

Technical Field

[0001] The present application relates to the field of water treatment, and more specifically, to a solid-phase-air flotation coupled treatment method for efficiently removing organic matter. Background Art

[0002] In the chemical, pharmaceutical and other industrial fields, high-concentration organic wastewater generated during production has become a major challenge for environmental governance. This type of organic wastewater is generally characterized by strong acidity (pH ≤ 1.5), multi-component complex toxicity and ultra-high chemical oxygen demand (COD> 20,000 mg / L), which brings great technical difficulties to traditional wastewater treatment technology. Specifically, these wastewaters use strong acids such as hydrochloric acid and phosphoric acid as media, and contain hydrophobic benzenes, polar formic acid, alkaline dimethylamine, highly toxic acrylonitrile (fish LC 50 =9mg / L), acrolein, heterocyclic pyridine and other toxic and harmful pollutants.

[0003] Therefore, existing water treatment methods for these types of organic wastewater have shortcomings. When using biochemical treatment methods, the highly acidic environment severely damages the cell structure of microorganisms. At the same time, highly toxic substances such as acrylonitrile have a strong inhibitory effect on microorganisms, causing the biochemical treatment system to collapse and failing to effectively remove organic pollutants in the wastewater. When using advanced oxidation methods such as Fenton oxidation, chlorine free radicals are easily generated in chlorine-containing media, triggering a chain chlorination side reaction, generating dioxin-like highly toxic substances with a toxic equivalent 10-100 times higher, causing serious secondary pollution.

[0004] When using solvent extraction to treat strongly acidic wastewater, amine extractants are prone to irreversible protonation, generating insoluble ion-pair compounds and resulting in a loss of organic phase partitioning functionality. Furthermore, competition among multiple components leads to low extraction efficiency, and the reliance on energy-intensive distillation facilities makes industrial application difficult. Currently, there are documented attempts to separate pollutants using flotation technology by capturing them through microbubbles. However, under strongly acidic conditions, the main functional components, anionic and cationic surfactants, are prone to protonation and precipitation, resulting in the failure of the gas-liquid interfacial tension control system and severely impacting pollutant removal efficiency.

[0005] In view of the limitations and difficulties of current common water treatment methods in removing organic pollutants in strong acid environments, how to achieve efficient removal of multi-component high-concentration organic pollutants under strong acid conditions has broad application prospects and important environmental value in the field of water treatment. Summary of the Invention

[0006] In order to achieve efficient removal of multi-component high-concentration organic pollutants under strongly acidic conditions, the present application provides a solid-phase-air flotation coupled treatment method for efficiently removing organic matter.

[0007] This application provides a solid-phase-air flotation coupling treatment method for efficiently removing organic matter, which adopts the following technical solutions: A solid-phase-air flotation coupling treatment method for efficiently removing organic matter comprises the following steps: S1. Add sodium chloride and surfactant to the wastewater to be treated, and then add solid flotation agent; S2. Gas is introduced into the wastewater to be treated for flotation treatment, and the scum above the wastewater is separated by a filter to remove organic matter in the wastewater; In step S1, the solid flotation agent is obtained by using worm graphite as a carrier and being treated in a mixed solvent of an organic amine, a diluent and a solubilizer.

[0008] By adopting the above technical solution, in this application, worm-like graphite is used as a matrix and is treated with a mixed solvent of organic amine, diluent and solubilizer. The ultra-high specific surface area and extreme pH stability of worm-like graphite are utilized to construct a physical adsorption substrate. Its unique worm-like multi-level pore structure can form a three-dimensional entanglement space during the adsorption of organic matter, thereby realizing the storage of organic matter. The mixed solvent is embedded in the mesoporous network of the worm-like graphite, significantly expanding the capacity of the entanglement space. In addition, the protonation of the amino group of the organic amine can enhance its electrostatic attraction with negatively charged organic matter, forming an acid-stable graphite hybrid material with both efficient physical adsorption and selective extraction functions. It is used as a solid flotation agent to achieve adsorption and extraction of organic matter in wastewater.

[0009] The treatment method in the present application is also combined with the treatment of sodium chloride and surfactant. In strongly acidic wastewater, many organic matter and colloidal particles carry an electric charge, forming a double-layer structure to stabilize the colloid. After the addition of sodium chloride, the ion concentration in the solution increases, compressing the double layer of the colloidal particles, destroying the colloid stability, and causing colloidal ion coagulation. At the same time, the salting-out effect promotes the precipitation of hydrophobic organic matter from the aqueous phase, driving its directional migration, which is beneficial to the adsorption of organic matter with bubbles and solid flotation agents, ensuring the enrichment and stability of organic pollutants. The surfactant forms a stable film on the surface of the bubbles, reducing the surface tension of the bubbles, making the bubbles more stable, and at the same time promoting the enrichment of hydrophobic organic matter on the bubble surface, thereby enhancing the bubbles' carrying capacity for organic pollutants.

[0010] Ultimately, this application adds sodium chloride, a surfactant, and a solid flotation agent to wastewater, followed by flotation treatment, to generate a large number of microbubbles. Hydrophobic organic matter in the wastewater is directly adsorbed on the bubble surfaces, floats with the bubbles to the flotation layer, and dissolves in the flotation layer. Simultaneously, because the solid flotation agent has an adsorption and extraction effect on organic matter in the wastewater, and the surfactant reduces the air-liquid interfacial tension, it makes it easier for hydrophobic organic matter to adsorb on the bubble surfaces. As the bubbles rise, the bubbles adsorbed with organic matter gather on the wastewater surface to form a scum. Utilizing the low density of worm-like graphite and the action of the surfactant, the solid flotation agent also floats on the water surface, forming a flotation layer, further adsorbing organic matter in the water. Ultimately, during the flotation process, the organic matter, under the synergistic action of the bubbles and the solid flotation agent, forms a pollutant-rich scum that floats to the liquid surface. The scum above the wastewater is separated by a filter, separating the flotation adsorption phase from the aqueous phase, thereby removing the organic matter from the wastewater. This solves the current problem of difficult separation of liquid flotation and the aqueous phase.

[0011] The method provided in this application leverages the extreme pH stability of worm-shaped graphite and organic amines to overcome the challenge of removing multi-component organic pollutants under strongly acidic conditions, achieving efficient and low-cost wastewater treatment. Furthermore, the solid flotation agent employed in this method is regenerative, enabling efficient solvent recovery and low-energy regeneration through backwashing with NaOH solution, dissociating ion pairs, and coupled with low-temperature thermal desorption at 80°C. This further reduces treatment costs and improves the sustainability and economic viability of the method.

[0012] Optionally, the organic amine is selected from one or more of N235, N503, and N1923, more preferably N235; the diluent is selected from one or more of kerosene, n-hexane, cyclohexane and toluene, more preferably a composite of kerosene and n-hexane; the solubilizer is selected from one or more of n-octanol, isooctyl alcohol, sec-octanol, cyclohexanol and diethylene glycol monobutyl ether.

[0013] By adopting the above technical solution, tertiary amine organic amines such as N235 (trialkyl tertiary amine) are used as the main extractant. The tertiary amine groups in the molecular structure are protonated under acidic conditions to form positively charged cations, which can combine with organic matter such as dyes, phenols, and carboxylic acids in wastewater through electrostatic attraction or coordination bonds to form hydrophobic complexes. On the other hand, n-octanol forms hydrogen bonds with polar organic matter to enhance its solubility in kerosene, which helps the above-mentioned flotation reagents capture organic matter. It can also eliminate the viscous third phase formed during N235 extraction, so that the complex formed by the organic amine is evenly dispersed in the kerosene.

[0014] Kerosene has good solubility for organic amines and organic complexes, forming a stable organic phase. At the same time, the low surface tension of kerosene helps bubbles to exist stably in the organic phase, improving the flotation separation efficiency. Moreover, by adjusting the viscosity, the bubbles and flotation reagents are more firmly attached, which helps to increase the flotation speed. During the flotation process, the negatively charged surface of the microbubbles and the positively charged organic amine-organic complex are combined through electrostatic attraction to form a bubble-extractant-organic three-phase complex, which can float to the water surface quickly.

[0015] Optionally, the organic amine is N235, the diluent is kerosene and n-hexane in a mass ratio of 1: (0.3-0.5), and the solubilizer is octanol.

[0016] By adopting the above technical solution, the viscosity of n-hexane is lower than that of kerosene, which can further reduce the viscosity of the system, making it more conducive to contact with wastewater and loading on worm graphite. It has better compatibility and solubility with kerosene for organic amines and solubilizers, and promotes the stable existence of microbubbles in the organic phase.

[0017] Optionally, the solid flotation agent is prepared by the following method: 1) Mix the organic amine, diluent and solubilizer, and ultrasonically treat for 20-30 minutes to prepare a mixed solvent; 2) After drying the worm graphite, immerse it in a mixed solvent, ultrasonically immerse it for 20-30 minutes, and then treat it under vacuum conditions of -0.1-(-0.2) MPa and 60±5°C for 1.5-2.5 hours. Then, filter and remove the solvent to obtain a solid flotation agent.

[0018] Optionally, when preparing the solid flotation agent, the volume ratio of the organic amine, the diluent and the solubilizer in step 1) is (1-4): (2-5): 1; In step 2), the added mass volume ratio of the worm graphite to the mixed solvent is 20-40 mL / g.

[0019] By adopting the above technical solution, in this application, the worm graphite is first vacuum dried to remove the water adsorbed in the pores, and then it is gradient loaded using the ultrasound-vacuum system. First, ultrasonic penetration is performed, and the cavitation effect of the ultrasonic treatment is used to open the mesoporous channels for penetration. Then, it is immersed under vacuum negative pressure conditions to drive the mixed solvent to fill the deeper pores of the worm graphite, thereby increasing its adsorption capacity.

[0020] Optionally, in step S1, the surfactant is prepared as a 1-10 wt% surfactant solution, and the added volume ratio of the surfactant solution to the wastewater to be treated is (0.2-0.5):100; Sodium chloride is prepared into a 1-10 wt% sodium chloride solution and added to the wastewater to be treated to a concentration of 20-30 mg / mL; The mass volume ratio of the solid flotation agent added to the wastewater to be treated is 5-10 mg / mL.

[0021] By adopting the above technical solution, the amount of surfactant and sodium chloride added is controlled in coordination with the interfacial tension control, thereby achieving a synergistic improvement in the capture of organic matter.

[0022] Optionally, the surfactant is a zwitterionic surfactant.

[0023] By adopting the above technical solution and selecting an amphoteric surfactant, the self-balancing effect of the charge can not only enhance the extraction of organic matter by the acid-stable bifunctional graphite hybrid material, i.e., the solid flotation agent, but also reduce the gas-liquid interfacial tension, promote the enrichment of hydrophobic organic matter, and ultimately improve the efficiency of simultaneous removal of multi-component organic matter including polar organic matter and hydrophobic organic matter in the present application. In addition, the material will not react with the alkaline washing solution during the regeneration process, thereby ensuring the cyclic stability of the material.

[0024] Optionally, the solid flotation agent in the scum in step S2 is sequentially backwashed with sodium hydroxide and subjected to low-temperature thermal desorption at 80±5° C. before being regenerated and recycled.

[0025] By adopting the above technical solution, the solid flotation agent in the scum obtained after adsorption of organic matter in the present application is subjected to sodium hydroxide alkaline backwashing treatment, and the bonding and dissociation of ion pairs, combined with low-temperature thermal desorption treatment, can achieve efficient recovery of solvent molecules, and at the same time achieve regeneration of the solid flotation agent, achieve efficient recycling, significantly reduce the cost of use, and overcome the non-renewable defect of flotation solvent.

[0026] Optionally, when preparing the solid flotation agent, the vermicular graphite is dried in step 2) and then pretreated before being treated in a mixed solvent. The specific pretreatment operation is as follows: The dried worm graphite is first immersed in a hydrogen peroxide solution with a mass concentration of 3-5% for 30-40 minutes, then modified and immersed in a modification solution containing aminosilane coupling agent, PAMAM, 4-mercaptobenzoic acid, terephthalic acid and genipin for 30-40 minutes, and then vacuum dried and treated in a mixed solvent.

[0027] By adopting the above technical solution, the worm graphite is first immersed in a hydrogen peroxide solution to introduce oxygen-containing functional groups such as hydroxyl and carboxyl groups on the surface of the worm graphite. Then, after being treated with a modification solution, the aminosilane coupling agent in the modification solution is added to combine with the surface of the worm graphite through silicon-oxygen bonds to introduce amino groups. PAMAM, as a dendritic amine molecular structure with a multi-level branched structure, especially containing multiple tertiary amine groups and secondary amine groups, can form a three-dimensional adsorption site to enhance the capture ability of organic matter. At the same time, under the action of genipin, its amino group can react with organic amines such as N235 in the mixed solvent. A certain cross-linking is formed to enhance the adhesion of organic amines on worm graphite, further enhance its organic matter capture and adsorption performance, and improve the removal effect of organic matter. The addition of 4-mercaptobenzoic acid and terephthalic acid, while the carboxyl group forms a chemical bond with the amino group, introduces a benzene ring group, and utilizes the π-π interaction between the benzene ring group and the organic matter to enhance the adsorption of organic matter. At the same time, its hydrophobicity is also improved, making it easier to adhere to bubbles and promote flotation separation. The introduction of carboxylic acid groups can enhance the polar interaction with organic matter, enhance the adsorption of target pollutants, and improve the water treatment effect.

[0028] Optionally, the modified liquid is prepared by mixing the following raw materials in parts by weight: 3-8 parts of aminosilane coupling agent, 8-14 parts of PAMAM, 1-3 parts of 4-mercaptobenzoic acid, 3-5 parts of terephthalic acid, 0.5-1.5 parts of genipin, 25-35 parts of water and 15-20 parts of ethanol.

[0029] By adopting the above technical solution, by controlling the amount of PAMAM and 4-mercaptobenzoic acid added, on the one hand, the chelation of the sulfhydryl group in 4-mercaptobenzoic acid with the metal ions is prevented, resulting in an increase in the density of the worm graphite affecting its flotation effect. Therefore, a small amount of 4-mercaptobenzoic acid is added in the present application, which neither causes the density of the worm graphite to increase and affect its flotation treatment and subsequent separation. Moreover, the introduced sulfhydryl group and the carboxyl group act synergistically to form a "hydrophobic-polar" bifunctional adsorption site, thereby improving the adsorption capacity of organic matter. Moreover, the sulfhydryl group and the amino group form a cross-linked structure, which can resist the competitive adsorption of metal ions on the one hand, and on the other hand, it also helps to improve the stability of the above-mentioned modification on the worm graphite, which can more effectively and for a long time play the effect of removing organic matter. In addition, the dendritic structure of PAMAM in the present application cooperates with the pore structure of the worm graphite to form a hierarchical adsorption space, which increases the adsorption sites and diffusion paths of organic molecules, and the control of its addition amount prevents the excessive number of secondary amine groups contained therein from affecting the organic matter extraction and removal effect, ultimately having a better effect on organic matter removal.

[0030] In summary, this application has the following beneficial effects: 1. In this application, an organic flotation agent containing an organic amine, a solubilizer, and a diluent is loaded on highly adsorbable expanded worm graphite to form a composite medium as a solid flotation agent, which is added to organic wastewater, coordinated with sodium chloride and a surfactant, and gas is introduced. Under the action of the surfactant, the solid flotation agent floats on the water surface to form a flotation layer. The hydrophobic organic matter in the wastewater is adsorbed on the surface of the bubbles and floats to the surface of the water phase with the bubbles and dissolves in the flotation layer. The flotation adsorption phase is separated from the water phase by a filter, thereby achieving efficient removal of pollutants. 2. The solid flotation agent in this application is based on vermicular graphite, which has extreme pH stability and is combined with the pH stability of organic amines. The prepared solid flotation agent is an acid-stable graphite hybrid material, which has excellent organic matter removal effect for wastewater systems where complex organic matter and strong acid coexist. In addition, the separation operation is simple and fast, and the operating cost is low; 3. The coupling of microbubble capture and surface-modified worm graphite achieves dual removal of hydrophobic and polar organic matter. The process does not require pre-neutralization, is compatible with conventional flotation equipment, and the medium can be regenerated by alkali washing, which greatly reduces the overall treatment cost and is suitable for the treatment of high-concentration oily wastewater. It also overcomes the cumbersome separation of the organic phase and the aqueous phase after liquid solvent flotation, which increases the cost of sewage treatment. At the same time, it also solves the problem of increased COD in wastewater caused by the slight solubility of the flotation organic solvent in the aqueous phase. DETAILED DESCRIPTION

[0031] The present application is further described in detail below with reference to the examples. It is particularly noted that if no specific conditions are specified in the following examples, the reactions are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following examples can be obtained from common commercial sources.

[0032] The specific surface area of ​​the vermicular graphite in this application is ≥50m 2 / g, expansion volume 200-300mL / g; the density of the worm graphite in the following preparation example is 0.7g / cm 3 .

[0033] The following preparation example is a preparation example of a solid flotation agent Preparation Example 1 A method for preparing a solid flotation agent comprises the following steps: 1) Mixing organic amine N235, diluent kerosene, and solubilizer n-octanol in a volume ratio of 1:2:1, and ultrasonically treating the mixture at a frequency of 40 kHz for 25 minutes to prepare a mixed solvent; 2) The worm graphite was dried at 105°C for 4 hours and then immersed in a mixed solvent. After ultrasonic immersion treatment at a frequency of 40 kHz for 25 minutes, it was vacuumed to -0.1 MPa and treated at 60°C for 2 hours. The solvent was then removed by filtration and dried to obtain a solid flotation agent.

[0034] Wherein, in step 2), the added mass volume ratio of the worm graphite to the mixed solvent is 30 mL / g, that is, 1 g of worm graphite is immersed in 30 ml of the mixed solvent.

[0035] Preparation Example 2 A method for preparing a solid flotation agent comprises the following steps: 1) Mixing organic amine N235, diluent kerosene and solubilizer n-octanol in a volume ratio of 2:3:1, and ultrasonically treating at a frequency of 40 kHz for 20 minutes to prepare a mixed solvent; 2) The worm graphite was dried at 103°C for 4 hours and then immersed in a mixed solvent. After ultrasonic immersion treatment at a frequency of 40 kHz for 20 minutes, it was vacuumed to -0.1 MPa and treated at 55°C for 2.5 hours. The solvent was then filtered off and dried to obtain a solid flotation agent.

[0036] Wherein, in step 2), the added mass volume ratio of the worm graphite to the mixed solvent is 20 mL / g, that is, 1 g of worm graphite is immersed in 20 ml of the mixed solvent.

[0037] Preparation Example 3 A method for preparing a solid flotation agent comprises the following steps: 1) Mixing organic amine N235, diluent kerosene and solubilizer n-octanol in a volume ratio of 4:5:1, and ultrasonically treating at a frequency of 40 kHz for 30 minutes to prepare a mixed solvent; 2) The worm graphite was dried at 107°C for 4 hours and then immersed in a mixed solvent. After ultrasonic immersion treatment at a frequency of 40 kHz for 30 minutes, it was vacuumed to -0.2 MPa and treated at 65°C for 1.5 hours. The solvent was then filtered off and dried to obtain a solid flotation agent.

[0038] Wherein, in step 2), the added mass volume ratio of the worm graphite to the mixed solvent is 40 mL / g, that is, 1 g of worm graphite is immersed in 40 ml of the mixed solvent.

[0039] Preparation Example 4 A method for preparing a solid suspension concentrate is carried out according to the method in Preparation Example 1, except that in step 1), the organic amine N235, the diluent kerosene and the solubilizer n-octanol are mixed in a volume ratio of 4:5:1.

[0040] Preparation Example 5 A method for preparing a solid suspension concentrate is carried out according to the method in Preparation Example 1, except that in step 1), the organic amine N235, the diluent kerosene and the solubilizer n-octanol are mixed in a volume ratio of 2:2:1.

[0041] Preparation Example 6 A method for preparing a solid suspension concentrate is carried out according to the method in Preparation Example 1, except that in step 1), the organic amine N235, the diluent kerosene and the solubilizer n-octanol are mixed in a volume ratio of 1:5:4.

[0042] Preparation Example 7 A method for preparing a solid suspension concentrate is carried out according to the method in Preparation Example 1, except that in step 1), the diluent is kerosene and n-hexane in a mass ratio of 1:0.4.

[0043] Preparation Example 8 A method for preparing a solid suspension concentrate is carried out according to the method in Preparation Example 1, except that in step 1), the diluent is kerosene and n-hexane in a mass ratio of 1:0.3.

[0044] Preparation Example 9 A method for preparing a solid suspension concentrate is carried out according to the method in Preparation Example 1, except that in step 1), the diluent is kerosene and n-hexane in a mass ratio of 1:0.5.

[0045] Preparation Example 10 A method for preparing a solid suspension concentrate is carried out according to the method in Preparation Example 1, except that the organic amine in step 1) is primary amine N-1923.

[0046] Preparation Example 11 A method for preparing a solid suspension concentrate is carried out according to the method in Preparation Example 1, except that the specific operation of step 2) is as follows: The worm-like graphite was dried at 105°C for 4 hours and then immersed in a 4% hydrogen peroxide solution for 35 minutes. The amount of hydrogen peroxide solution added was 7 times the mass of the worm-like graphite. The activated worm-like graphite was then obtained by filtration. Then, 5 parts of aminosilane coupling agent, 12 parts of PAMAM, 2 parts of 4-mercaptobenzoic acid, 4 parts of terephthalic acid, 1 part of genipin, 30 parts of water and 18 parts of ethanol were mixed to prepare a modification solution, and the prepared activated worm-like graphite was modified and impregnated in the modification solution for 35 minutes. The mass ratio of the modification solution to the activated worm-like graphite was 5:1, the impregnation temperature was 45°C, and the mixture was vacuum dried after the impregnation to obtain pretreated worm-like graphite. The pretreated vermicular graphite is then immersed in a mixed solvent for treatment in the same manner as in Preparation Example 1.

[0047] Preparation Example 12 A method for preparing a solid suspension concentrate is carried out according to the method in Preparation Example 1, except that the specific operation of step 2) is as follows: The worm-like graphite was dried at 105°C for 4 hours and then immersed in a 3% hydrogen peroxide solution for 30 minutes. The amount of hydrogen peroxide solution added was 6 times the mass of the worm-like graphite. The activated worm-like graphite was then obtained by filtration. Then, 3 parts of aminosilane coupling agent, 8 parts of PAMAM, 1 part of 4-mercaptobenzoic acid, 3 parts of terephthalic acid, 0.5 parts of genipin, 25 parts of water and 15 parts of ethanol were mixed to prepare a modification solution, and the prepared activated worm-like graphite was modified and impregnated in the modification solution for 30 minutes. The mass ratio of the modification solution to the activated worm-like graphite was 4:1, the impregnation temperature was 40°C, and the pretreated worm-like graphite was vacuum dried after the impregnation. The pretreated vermicular graphite is then immersed in a mixed solvent for treatment in the same manner as in Preparation Example 1.

[0048] Preparation Example 13 A method for preparing a solid suspension concentrate is carried out according to the method in Preparation Example 1, except that the specific operation of step 2) is as follows: The worm-like graphite was dried at 105°C for 4 hours and then immersed in a 5% hydrogen peroxide solution for 40 minutes. The amount of hydrogen peroxide solution added was 8 times the mass of the worm-like graphite. The activated worm-like graphite was then obtained by filtration. Then, 8 parts of aminosilane coupling agent, 14 parts of PAMAM, 3 parts of 4-mercaptobenzoic acid, 5 parts of terephthalic acid, 1.5 parts of genipin, 35 parts of water and 20 parts of ethanol were mixed to prepare a modification solution, and the prepared activated worm-like graphite was modified and impregnated in the modification solution for 40 minutes. The mass ratio of the modification solution to the activated worm-like graphite was 6:1, the impregnation temperature was 50°C, and the mixture was vacuum dried after the impregnation to obtain pretreated worm-like graphite. The pretreated vermicular graphite is then immersed in a mixed solvent for treatment in the same manner as in Preparation Example 1.

[0049] Preparation Example 14 A method for preparing a solid flotation agent is carried out according to the method in Preparation Example 11, except that 4-mercaptobenzoic acid and terephthalic acid are not added to the modified liquid.

[0050] Preparation Example 15 A method for preparing a solid flotation agent is carried out according to the method in Preparation Example 11, except that an equal amount of 4-mercaptobenzoic acid in the modifying liquid is replaced by terephthalic acid.

[0051] Preparation Example 16 A method for preparing a solid flotation agent is carried out according to the method in Preparation Example 11, except that PAMAM is not added to the modified liquid.

[0052] Example 1 A solid-phase-air flotation coupling treatment method for efficiently removing organic matter comprises the following steps: S1, adding sodium chloride and an amphoteric surfactant to the wastewater to be treated, and then adding the solid flotation agent prepared in Preparation Example 1, wherein the amphoteric surfactant is specifically selected from dodecyl dimethyl betaine BS-12; In step S1, a surfactant solution of 5 wt% is prepared by mixing the surfactant with water, and the added volume ratio of the surfactant solution to the wastewater to be treated is 0.3:100; Sodium chloride is mixed with water to prepare a 5 wt% sodium chloride solution, and the sodium chloride is added to the wastewater to be treated to a concentration of 25 mg / mL; The mass volume ratio of solid flotation agent added to the wastewater to be treated is 8 mg / mL (that is, 8 mg of solid flotation agent is added to 1 ml of wastewater); S2. Air is introduced into the wastewater to be treated for flotation treatment for 1 hour at a gas flow rate of 0.4 L / min·L wastewater (i.e., 0.4 L of gas is introduced per minute for every liter of wastewater). After the flotation treatment is completed, the scum above the wastewater is separated by a filter to remove organic matter in the wastewater, and the treated purified water is discharged from the overflow port at the top of the flotation unit.

[0053] Example 2 A solid-phase-air flotation coupling treatment method for efficiently removing organic matter comprises the following steps: S1, adding sodium chloride and an amphoteric surfactant to the wastewater to be treated, and then adding the solid flotation agent prepared in Preparation Example 2, wherein the amphoteric surfactant is specifically selected from dodecyl dimethyl betaine BS-12; In step S1, a surfactant solution of 1 wt% is prepared by mixing the surfactant with water, and the added volume ratio of the surfactant solution to the wastewater to be treated is 0.5:100; Sodium chloride is mixed with water to prepare a 1 wt% sodium chloride solution, and the sodium chloride is added to the wastewater to be treated to a concentration of 30 mg / mL; The mass volume ratio of solid flotation agent added to the wastewater to be treated is 5 mg / mL (that is, 5 mg of solid flotation agent is added to 1 ml of wastewater); S2. Air is introduced into the wastewater to be treated for flotation treatment for 1 hour at a gas flow rate of 0.3 L / min·L wastewater (i.e., 0.3 L of gas is introduced per minute for every liter of wastewater). After the flotation treatment is completed, the scum above the wastewater is separated by a filter to remove organic matter in the wastewater, and the treated purified water is discharged from the overflow port at the top of the flotation unit.

[0054] Example 3 A solid-phase-air flotation coupling treatment method for efficiently removing organic matter comprises the following steps: S1, adding sodium chloride and an amphoteric surfactant to the wastewater to be treated, and then adding the solid flotation agent prepared in Preparation Example 3, wherein the amphoteric surfactant is specifically selected from dodecyl dimethyl betaine BS-12; In step S1, a surfactant solution of 10 wt% is prepared by mixing the surfactant with water, and the added volume ratio of the surfactant solution to the wastewater to be treated is 0.2:100; Sodium chloride is mixed with water to prepare a 10 wt% sodium chloride solution, and the sodium chloride is added to the wastewater to be treated to a concentration of 20 mg / mL; The mass volume ratio of solid flotation agent added to the wastewater to be treated is 10 mg / mL (that is, 10 mg of solid flotation agent is added to 1 ml of wastewater); S2. Air is introduced into the wastewater to be treated for flotation treatment for 1 hour at a gas flow rate of 0.5 L / min·L wastewater (i.e., 0.5 L of gas is introduced per minute for every liter of wastewater). After the flotation treatment is completed, the scum above the wastewater is separated by a filter to remove organic matter in the wastewater, and the treated purified water is discharged from the overflow port at the top of the flotation unit.

[0055] Examples 4-16 A solid-phase-air flotation coupled treatment method for efficiently removing organic matter is carried out according to the method in Example 1, except that the solid flotation agent added in step S1 is the solid flotation agent prepared in Preparation Examples 4-16.

[0056] Comparative Example 1 A treatment method for efficiently removing organic matter by solid-phase-air flotation coupling is carried out according to the method in Example 1, except that sodium chloride is not added in step S1.

[0057] Comparative Example 2 A treatment method for efficiently removing organic matter by solid-phase-air flotation coupling is carried out according to the method in Example 1, except that no amphoteric surfactant is added in step S1.

[0058] Comparative Example 3 A treatment method for efficiently removing organic matter by solid-phase-air flotation coupling is carried out according to the method of Example 1, except that the solid flotation agent in step S1 is replaced by an equal amount of a mixed solvent, and the mixed solvent is obtained by mixing tertiary amine N235, kerosene, and n-octanol in a volume ratio of 2:3:1.

[0059] Comparative Example 4 A treatment method for efficiently removing organic matter by coupling solid phase and air flotation is carried out according to the method of Example 1, except that the solid flotation agent in step S1 is replaced in equal amounts by a mixture of worm-shaped graphite and a mixed solvent, the mixed solvent is obtained by mixing tertiary amine N235, kerosene, and n-octanol in a volume ratio of 2:3:1, and the mass ratio of worm-shaped graphite to the mixed solvent is 1:25.

[0060] Comparative Example 5 A treatment method for efficiently removing organic matter by coupling solid phase and air flotation is carried out according to the method in Example 1, except that an equal amount of the solid flotation agent in step S1 is replaced by vermicular graphite.

[0061] Performance testing Ultra-high concentration wastewater with a pH value of 1.5 and a COD content of 153820 mg / L was treated according to the methods in the above embodiments and comparative examples, and the COD removal rate after 1 hour of flotation treatment was statistically analyzed. The statistical results are shown in Table 1 below.

[0062] Table 1: Combined with the test results in Table 1 above, the solid flotation agent formed by worm-shaped graphite loaded with an organic amine such as tertiary amine N235 and a mixed solvent of kerosene and octanol in the examples of the present application has excellent treatment stability for strongly acidic wastewater with a pH of 0-2 and high-concentration wastewater. When forming an acid-stable hybrid material, it has a stable and excellent treatment effect for removing organic matter.

[0063] Combining the test results of Example 1 with those of Examples 4-6, it can be seen that the addition ratio of N235 in the mixed solvent has a significant effect on its removal effect. When the proportion of N235 in Example 6 is too small, its effect is the weakest. When the mass ratio of N235: octanol: kerosene in Example 1 is 1:1:2, its removal effect is better. Combined with the test results of Examples 7-9, when a mixture of kerosene and n-hexane is selected as the diluent, the organic matter removal effect is improved compared to single kerosene. Combined with the test results of Example 10, tertiary amines are selected as organic amines, which have better water treatment removal effects than primary amines. Combined with the test results in Examples 11-13, the worm graphite is first pretreated before the mixed solvent is prepared. The pretreatment process not only helps to introduce active functional groups to improve the adsorption of organic matter, but also helps to strengthen the binding strength of the mixed solvent to the worm graphite, further improving its organic matter removal effect, and ultimately further improving the organic matter removal effect. Combined with the test results of Example 11, Examples 14 and 15, the organic matter removal efficiency was reduced when no benzene-containing substance or mercaptobenzoic acid was added to the modified solution. Combined with the test results of Example 16, the organic matter removal efficiency was significantly reduced when no PAMAM was added to the modified solution.

[0064] Combining the test results of Example 1 with those of Comparative Examples 1 and 2, the organic matter removal efficiency was significantly reduced when sodium chloride and surfactant were not added to the wastewater. The combination of sodium chloride, surfactant, and the solid flotation agent of the present application contributed to the organic matter removal efficiency. Combining the test results of Comparative Example 3, the organic matter removal efficiency was reduced when the mixed solvent was directly added as the liquid flotation agent. More importantly, the subsequent separation of the solid flotation phase and the aqueous phase in Example 1 was simpler and more convenient, while the separation was inconvenient when the liquid flotation used upper overflow in Comparative Example 3. Combining the methods of Comparative Examples 4 and 5, in Comparative Example 4, vermicular graphite and the mixed solvent were directly added to the wastewater for treatment, without any loading treatment. However, the subsequent separation of the liquid flotation agent from the wastewater was difficult, resulting in the residual liquid flotation agent in the aqueous phase, which significantly reduced the organic matter removal efficiency. Combining the test results of Comparative Example 5, the removal efficiency was also significantly reduced when only vermicular graphite was used for flotation removal of organic matter.

[0065] In addition, the solid flotation agent in the scum in the treatment methods of Example 1 and Example 11 was cleaned with a sodium hydroxide solution with a mass concentration of 5%, and then heat-treated at 80°C for 2 hours before regeneration. It was reused, and the COD removal rate after 5 repeated regenerations was statistically calculated. After treatment using the method of Example 1, the COD removal rate reached 25.6, and the COD removal rate in Example 11 reached 44.8. The solid flotation agent in Example 1 had a better removal effect after regeneration.

[0066] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A solid-phase-air flotation coupling treatment method for efficiently removing organic matter, characterized in that: The following steps are involved: S1. Add sodium chloride and surfactant to the wastewater to be treated, and then add solid flotation agent; S2. Gas is introduced into the wastewater to be treated for flotation treatment, and the scum above the wastewater is separated by a filter to remove organic matter from the wastewater; In step S1, the solid flotation agent is obtained by using worm graphite as a carrier and being treated in a mixed solvent of an organic amine, a diluent and a solubilizer.

2. The method for efficiently removing organic matter by coupling solid-phase flotation according to claim 1, characterized in that: The organic amine is selected from one or more of N235, N503, and N1923; The diluent is selected from one or more of kerosene, n-hexane, cyclohexane and toluene; The solubilizer is selected from one or more of n-octanol, isooctyl alcohol, sec-octanol, cyclohexanol and diethylene glycol monobutyl ether.

3. The method for efficiently removing organic matter by coupling solid-phase flotation according to claim 1, characterized in that: The organic amine is N235, the diluent is kerosene and n-hexane in a mass ratio of 1: (0.3-0.5), and the solubilizer is octanol.

4. The method for efficiently removing organic matter by coupling solid phase and air flotation according to claim 1, characterized in that: The solid flotation agent is prepared by the following method: 1) Mix the organic amine, diluent and solubilizer, and ultrasonically treat for 20-30 minutes to prepare a mixed solvent; 2) After drying the worm graphite, immerse it in a mixed solvent, ultrasonically immerse it for 20-30 minutes, and then treat it under vacuum conditions of -0.1-(-0.2) MPa and 60±5°C for 1.5-2.5 hours. Then, the solvent is removed by filtration to obtain a solid flotation agent.

5. The method for efficiently removing organic matter by coupling solid phase and air flotation according to claim 4, characterized in that: When preparing the solid flotation agent, the volume ratio of the organic amine, diluent and solubilizer in step 1) is (1-4): (2-5): 1; In step 2), the added mass volume ratio of the worm graphite to the mixed solvent is 20-40 mL / g.

6. The method for efficiently removing organic matter by coupling solid-phase flotation according to claim 1, characterized in that: In step S1, the surfactant is prepared as a 1-10 wt% surfactant solution, and the added volume ratio of the surfactant solution to the wastewater to be treated is (0.2-0.5):100; Sodium chloride is prepared as a 1-10 wt% sodium chloride solution and added to the wastewater to be treated to a concentration of 20-30 mg / mL; The mass volume ratio of the solid flotation agent added to the wastewater to be treated is 5-10 mg / mL.

7. The method for efficiently removing organic matter by coupling solid-phase flotation according to claim 1, characterized in that: The surfactant used is a zwitterionic surfactant.

8. The method for efficiently removing organic matter by coupling solid-phase flotation according to claim 1, characterized in that: In step S2, the solid flotation agent in the slag is sequentially backwashed with sodium hydroxide and subjected to low-temperature thermal desorption at 80±5° C. before being regenerated and recycled.

9. The method for efficiently removing organic matter by coupling solid-phase flotation according to claim 1, characterized in that: When preparing the solid flotation agent, in step 2), the worm graphite is dried and then pretreated in a mixed solvent. The specific pretreatment operation is as follows: The dried worm graphite is first immersed in a hydrogen peroxide solution with a mass concentration of 3-5% for 30-40 minutes, then modified and immersed in a modification solution containing aminosilane coupling agent, PAMAM, 4-mercaptobenzoic acid, terephthalic acid and genipin for 30-40 minutes, and then vacuum dried and treated in a mixed solvent.

10. The method for efficiently removing organic matter by solid-phase-air flotation coupling according to claim 9, characterized in that: The modified liquid is prepared by mixing the following raw materials in parts by weight: 3-8 parts of aminosilane coupling agent, 8-14 parts of PAMAM, 1-3 parts of 4-mercaptobenzoic acid, 3-5 parts of terephthalic acid, 0.5-1.5 parts of genipin, 25-35 parts of water and 15-20 parts of ethanol.

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