Foam separation aid, preparation method thereof and foam separation method for separating and enriching sulfur-containing ions in water body

Abstract

The invention discloses a foam separation aid, a preparation method thereof and a foam separation method for separating and enriching sulfur-containing ions in a water body. The foam separation aid comprises graphene oxide and a modifier. The preparation method comprises the following steps: dispersing graphene oxide in distilled water, and adding a modifier in proportion to obtain a turbid liquid; and adjusting the pH value of the suspension, stirring under a water bath condition until complete reaction, centrifuging, washing and drying to obtain the foam separation aid. Adding a foam separation aid into the to-be-separated liquid to form a feed liquid, injecting the feed liquid into a foam separation tower for foam separation, collecting foam, and defoaming the foam to obtain a defoaming liquid; adjusting the pH value of the defoaming liquid to be neutral, and then settling to obtain supernate and sediment; the supernate is used as a raw material for producing sulfate, and the sediment and the to-be-separated liquid are mixed and then sent to a foam separation tower for recycling. According to the surface adsorption principle, an organic reagent and a flocculating agent are not used, and efficient separation of sulfur-containing ions in an aqueous solution is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial wastewater treatment, and in particular to a foam separation aid (GO-LS) and a preparation method thereof, and a method for enriching and separating sulfur-containing ions (persulfate ions and sulfate ions) in an aqueous solution by a foam separation method. Background Art

[0002] In the field of wastewater treatment, advanced oxidation technology (AOP) uses metals (Fe, Co, Mn, etc.) and their oxides to catalyze superoxide to produce highly reactive oxygen (sulfate radicals (•SO4 - ), hydroxyl radicals (•OH) and superoxide radicals (•O2 - ) and non-radical singlet oxygen 1 O2, etc.), these active oxygen species have high redox potentials and can quickly and effectively convert toxic organic pollutants into harmless mineralized salts, carbon dioxide and water. However, in the process of degrading pollutants, persulfate will produce a large amount of sulfur-containing ions, including persulfate ions that are not involved in the degradation and sulfate ions produced by degradation. Among them, persulfate ions are oxidizing and unstable, and are easily reduced to sulfate ions; sulfate ions are non-toxic, but excessive sulfate ions will destroy the natural sulfur cycle and corrode buildings and equipment; excessive sulfate ions in the water environment will cause mineralization of the water body, produce odors, and even have adverse effects on the ecosystem.

[0003] At present, the methods for removing and separating sulfur-containing ions include chemical precipitation, biological treatment and physical adsorption. Among them, the chemical precipitation method first reduces persulfate ions to sulfate ions by a reducing agent, and then adds barium salt or calcium salt to precipitate sulfate ions. However, this method introduces new impurity ions and produces a large amount of sludge. The biological treatment method uses the ability of certain microorganisms to absorb sulfur-containing ions to purify sewage, but the process requires a strict microbial growth environment. Adsorption is the preferred method for removing sulfur-containing ions from water. It has the advantages of rapidity, high selectivity and sulfate ion removal potential, but it also has disadvantages and limitations such as weak adsorption capacity, high price, difficult adsorbent recovery, and secondary pollution. Although the above methods achieve the removal and separation of sulfur-containing ions, there are disadvantages such as complex operation, low removal efficiency, and easy secondary pollution in the separation process to varying degrees, which are not suitable for large-scale industrial applications. Therefore, it is of great significance to develop an efficient, green, and low-cost enrichment and separation method for the separation of sulfur-containing ions in water. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a foam separation aid (GO-LS) and a preparation method thereof and a foam separation method for separating and enriching sulfur-containing ions in water bodies. Based on the foam separation aid (GO-LS), sulfur-containing ions can be enriched and separated from water bodies without adding reducing agents and flocculants.

[0005] To solve the above technical problems, according to one aspect of the present invention, a foam separation aid (GO-LS) is provided, which comprises graphene oxide and a modifier, and the mass ratio of the two is 1:1~1:6; the modifier is selected from sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide, dodecyldimethyl betaine, cocoamidopropyl betaine, dodecylaminopropionic acid or sodium dodecylaminopropionate.

[0006] Furthermore, the mass ratio of graphene oxide to the modifier is 1:5.

[0007] According to another aspect of the present invention, provided is a method for preparing the above-mentioned foam separation aid (GO-LS), comprising: Step 1, dispersing graphene oxide in distilled water, and adding a modifier in proportion to obtain a suspension; Step 2: Adjust the pH of the suspension to 1.0-8.0, stir in a water bath at 75-95° C. until the reaction is complete, and obtain a foam separation aid (GO-LS) after centrifugation, washing, and drying.

[0008] According to another aspect of the present invention, provided is a foam separation method for separating and enriching sulfur ions in water, comprising: Step 1, preparation of feed liquid; Adding the foam separation aid (GO-LS) according to claim 1 or 2 to the liquid to be separated to form a feed liquid, and then adjusting the pH value of the feed liquid to 3.0-6.0; Step 2, foam separation; Injecting the feed liquid obtained in step 1 into a foam separation tower for foam separation, collecting the foam and defoaming the foam to obtain a defoaming liquid; Step three, adjusting the pH value of the defoaming liquid to neutral and then settling to obtain a supernatant and a precipitate; the supernatant is used as a raw material for producing sulfate, and the precipitate is mixed with the liquid to be separated and sent to a foam separation tower for recycling.

[0009] Furthermore, in step 1, the liquid to be separated is organic wastewater degraded by persulfate, including one or more combinations of organic wastewater degraded by potassium hydrogen persulfate, organic wastewater degraded by potassium persulfate, and organic wastewater degraded by ammonium persulfate.

[0010] Furthermore, in step 1, a foam separation aid (GO-LS) is added to the liquid to be separated at a concentration of 100-1200 mg / L.

[0011] Furthermore, a foam separation aid (GO-LS) was added to the liquid to be separated at a concentration of 600-1100 mg / L.

[0012] Furthermore, in step 1, the pH value of the feed solution is adjusted to 4.0-5.0.

[0013] Furthermore, a gas distributor is provided at the bottom of the foam separation tower, and the gas distributor, the air humidification bottle, the buffer bottle, and the air compressor are connected in sequence through pipelines to input gas into the foam separation tower.

[0014] Furthermore, in step 2, foam separation is performed at room temperature with a gas velocity of 100-600 mL / min and a foam layer height of 3 / 5-4 / 5 of the height of the foam separation tower, and the foam overflowing the top of the tower is collected.

[0015] The present invention provides a foam separation aid (GO-LS) and a foam separation technology based on the foam separation aid (GO-LS), and applies the GO-LS to enrich and separate sulfur-containing ions (persulfate ions and sulfate ions) in an aqueous solution. According to the surface adsorption principle, efficient separation of sulfur-containing ions can be achieved, the enrichment ratios of sulfate ions and persulfate ions can be greatly improved (4.8-23.3 and 3.1-16.2), and the removal rate can be increased (95.5%-98.9% and 92.8%-99.1%).

[0016] The present invention has the advantages of green and pollution-free process, no use of organic reagents and flocculants, low energy consumption and simple process, effectively solves the problem of separation of sulfur ions in aqueous solution, and has good economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention provides a process flow chart for enriching and separating sulfur ions in an aqueous solution using a foam separation method.

[0018] Figure 2 This is a schematic diagram of the foam separation equipment, in which 1-air compressor, 2-buffer bottle, 3-air humidification bottle, 4-flow meter, 5-water stop clamp, 6-residual liquid storage tank, 7-gas distributor, 8-foam separation tower, 9-feed pump, 10-feed liquid regulating tank, 11-defoaming liquid storage tank, and 12-collector.

[0019] Figure 3 It is the removal rate and enrichment ratio of sulfur-containing ions in Example 1.

[0020] Figure 4It is the removal rate and enrichment ratio of sulfur-containing ions in Example 2.

[0021] Figure 5 It is the removal rate and enrichment ratio of sulfur-containing ions in Example 3.

[0022] Figure 6 It is the removal rate and enrichment ratio of sulfur-containing ions in Example 4.

[0023] Figure 7 It is the removal rate and enrichment ratio of sulfur-containing ions in Comparative Example 1, Comparative Example 2 and Comparative Example 3. DETAILED DESCRIPTION

[0024] The basic concept of the present invention is to achieve simultaneous separation and enrichment of sulfur ions in aqueous solution by adding a foam separation aid (GO-LS) based on the preparation of the foam separation aid, according to the interfacial adsorption principle of foam separation. At the same time, the process has the advantages of simple steps, greenness, low energy consumption and low investment.

[0025] A typical embodiment of the present invention provides a foam separation aid (GO-LS), which includes graphene oxide and a modifier, wherein the modifier is selected from sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide, dodecyldimethyl betaine, cocoamidopropyl betaine, dodecylaminopropionic acid or sodium dodecylaminopropionate.

[0026] The mass ratio of graphene oxide to the modifier is 1:1 to 1:6, and the preferred mass ratio is 1:5.

[0027] The foam separation aid (GO-LS) provided in the above embodiment, as a foaming agent and a collector, can simultaneously enrich and separate persulfate and hydrogen persulfate degradation organic wastewater persulfate ions and sulfate ions. The foam separation aid (GO-LS) is reusable.

[0028] The preparation method of the foam separation aid (GO-LS) described above includes the following steps 1 and 2.

[0029] Step 1: Disperse graphene oxide in distilled water, and add a modifier in proportion to obtain a suspension.

[0030] Exemplarily, the graphene oxide in this step is prepared by Hummers oxidation method, and is dispersed in distilled water by ultrasound, and then a modifier is added according to a mass ratio of graphene oxide to modifier of 1:1 to 1:6.

[0031] Step 2: Adjust the pH of the suspension to 1.0-8.0, stir in a water bath at 75-95° C. until the reaction is complete, and obtain a foam separation aid (GO-LS) after centrifugation, washing, and drying.

[0032] The preferred pH of the suspension is 4.0. The water bath temperature is preferably 85°C, and the stirring time under the water bath condition is 2 to 4 h, preferably 3 h.

[0033] Another typical embodiment of the present invention provides a foam separation method for separating and enriching sulfur ions in water, which is based on Figure 2 The foam separation device shown in the figure includes an air compressor 1, a buffer bottle 2, an air humidifying bottle 3, a residual liquid storage tank 6, a gas distributor 7, a foam separation tower 8, a feed pump 9, a feed liquid regulating tank 10, a defoaming liquid storage tank 11, and a collector 12.

[0034] The inlet and outlet ends of the feed pump 9 are connected to the feed liquid regulating tank 10 and the foam separation tower 8 respectively. The wastewater with separated organic matter is injected into the feed liquid regulating tank 10 to adjust the pH value and add the foam separation aid (GO-LS) as the feed liquid for foam separation, and the feed liquid is input into the foam separation tower 8 through the feed pump 9.

[0035] The foam separation tower 8 is the main equipment for realizing foam separation, and is a hollow cylindrical structure. For example, any device and material that can perform foam separation in the prior art, such as a cylinder or a prism, can be selected, and the inner diameter can be the same or different in the height direction. The height and inner diameter of the column can be adjusted according to conventional use, and its height-to-diameter ratio is preferably 10-35:1. For a hollow cylinder, its height-to-diameter ratio is preferably 20-30:1.

[0036] During the foam separation process, the temperature, gas velocity and other conditions can be controlled. After the feed liquid is injected into the foam separation tower 8, the foam layer height is extended by adjusting the operating conditions to strengthen the foam drainage, reduce the volume of the defoaming liquid, and effectively enrich the sulfur-containing ions.

[0037] A gas distributor 7 is provided at the bottom of the foam separation tower 8. The gas distributor 7, the air humidification bottle 3, the buffer bottle 2, and the air compressor 1 are connected in sequence through pipelines to input gas into the foam separation tower 8. A flow meter 4 and a water stop clamp 5 are provided on the connecting pipeline between the gas distributor 7 and the air humidification bottle 3.

[0038] The collector 12 is arranged at the top of the foam separation tower 8, and is used to collect and defoam the foam flowing out of the top of the tower. The defoaming liquid is input into the defoaming liquid storage tank 11, and the pH value is adjusted to neutral and then settled to obtain a supernatant and a sediment, which are respectively input into the supernatant storage tank and the sediment storage tank.

[0039] The bottom of the foam separation tower 8 is connected to the residual liquid storage tank 11 through a pipeline, and the residual liquid at the bottom of the tower after the foam separation treatment can be directly discharged to the residual liquid storage tank 11.

[0040] On this basis, the foam separation method provided in this embodiment for separating and enriching sulfur-containing ions in water, especially the foam separation method for enriching and separating sulfur-containing ions (persulfate ions, sulfate ions) in organic wastewater degraded by persulfate and hydrogen persulfate, includes the following steps one to three.

[0041] Step 1, preparation of feed liquid; The foam separation aid (GO-LS) of the present invention is added to the liquid to be separated to form a feed liquid, and then the pH value of the feed liquid is adjusted to 3.0-6.0.

[0042] Wherein, illustratively, the liquid to be separated is organic wastewater degraded by persulfate, including one or more combinations of organic wastewater degraded by potassium hydrogen persulfate, organic wastewater degraded by potassium persulfate and organic wastewater degraded by ammonium persulfate.

[0043] In step 1, the foam separation aid (GO-LS) is preferably added to the liquid to be separated at a concentration of 100-1200 mg / L, and a further preferred solution is to add the foam separation aid (GO-LS) to the liquid to be separated at a concentration of 600-1100 mg / L.

[0044] In step 1, preferably, the pH value of the feed solution is adjusted to 4.0-5.0.

[0045] Step 2: Foam separation.

[0046] The feed liquid obtained in step 1 is injected into the foam separation tower 8 for foam separation, and the foam is collected and defoamed to obtain a defoaming liquid.

[0047] Compressed air is input into the foam separation tower 8 from the air compressor 1 through the buffer bottle 2, the air humidification bottle 3, the flow meter 4 and the gas distributor 7.

[0048] In this step, the persulfate ions and sulfate ions are captured from the solution to the gas-liquid interface by the foam separation aid (GO-LS), and as the foam layer rises, the foam flows into the collector 12 at the top of the tower, thereby enriching and separating the persulfate ions and sulfate ions.

[0049] The whole foam separation process is carried out at room temperature, the height of the foam layer is 3 / 5 to 4 / 5 of the height of the foam separation tower, and the gas velocity is 100 to 600 mL / min, preferably 100 to 500 mL / min. The foam flowing out of the top of the tower is collected and defoamed, and the ventilation is stopped when the foam can no longer overflow from the top of the foam separation tower. The liquid obtained by defoaming the foam collected from the top of the tower is the defoaming liquid.

[0050] Step three, adjusting the pH value of the defoaming liquid to neutral and then settling to obtain a supernatant and a precipitate; the supernatant is used as a raw material for producing sulfate, and the precipitate is mixed with the liquid to be separated and pumped to a foam separation tower for recycling through a feed pump, and the residual liquid at the bottom of the tower can be directly discharged after the foam separation treatment.

[0051] In the above implementation, the addition of foam separation aid (GO-LS) and the extension of foam height in foam separation can stabilize the structure of rising foam, promote the interface adsorption of sulfur-containing ions and fully strengthen the foam drainage, thus achieving a high enrichment of sulfur-containing ions in aqueous solution (the concentrations of persulfate ions and sulfate ions in the defoaming liquid are 1.5-3.8 g / L and 5.3-13.6 g / L, respectively). The obtained defoaming liquid can be used as a raw material for the production of sulfate after sedimentation. At the same time, it has the advantages of low investment, low energy consumption, no pollution and simple steps, which greatly reduces the difficulty and cost of enriching and separating sulfur-containing ions in aqueous solution.

[0052] The technical scheme claimed in the present invention is further described below by some examples. However, the examples and comparative examples are used to explain the embodiments of the present invention and do not exceed the scope of the subject matter of the present invention. The protection scope of the present invention is not limited by the examples. Unless otherwise specified, the materials and reagents used in the present invention can be obtained from commercial products in the art.

[0053] The "organic wastewater degradation by potassium persulfate and potassium hydrogen persulfate" used in the following examples and comparative examples was provided by the Environmental Electrocatalysis Laboratory of the Institute of Environmental Sciences of Shanxi University.

[0054] The sulfate ion concentration is determined according to the determination method given in "4.4 Barium chromate spectrophotometry (cold method)" in GB / T 5750.5-2023 Standard Test Method for Drinking Water, Part 5: Inorganic non-metallic indicators.

[0055] The persulfate ion concentration was determined according to the determination method given by Ye J et al. in “Synergy of pore confinement and co-catalytic effects in Peroxymonosulfate activation for persistent and selective removal of contaminants” in Chemical Engineering Journal, Vol. 496, 2024, Article No. 154034.

[0056] The foam performance test refers to the determination method given in "Equilibrium and Dynamic Surface Tension in Relation to Diffusivity and Foaming Properties: Effects of Surfactant Type and Structure" published by Kanokkarn et al. in "Colloids and Surfaces APhysicochemical and Engineering Aspects" Volume 524, 2017, Pages 135 to 142. A transparent plexiglass column with an inner diameter of 45 mm and a column height of 500 mm was used. 200 mL of solution was added to the column, and the gas rate was adjusted to 200 mL / min. The foam height generated within 60 s and the time required for the foam phase to drop to half the height were recorded. The former is the foam height, representing the foamability, and the latter is the foam half-life, representing the foam stability.

[0057] The calculation formula of "removal rate" is as follows: ; The calculation formula of the "enrichment ratio" described in this embodiment is as follows: .

[0058] Example 1: Enrichment and separation of sulfur ions in organic wastewater from potassium persulfate degradation Step 1: Preparation of Foam Separation Agent (GO-LS) Graphene oxide prepared by Hummers oxidation method was dispersed in distilled water, and modifier (dodecylaminopropionic acid) was added in a mass ratio of 1:1, 1:2, 1:3, 1:4, 1:5, 1:6. The pH value of the suspension was adjusted to 4.0, stirred in a water bath at 85℃ for 3 h, centrifuged at 8000 r / min for 10 min, and the precipitate was collected, washed to neutrality, and dried at 60℃ to obtain a foam separation aid (GO-LS). The foam heights of the foam separation aid (GO-LS) with modification ratios of 1:1, 1:2, 1:3, 1:4, 1:5, and 1:6 were 45, 100, 130, 180, 250, and 263 mm, respectively. The foam half-lives were 6.5, 12.0, 36.0, 50.5, 89.0, and 93.0 s, respectively.

[0059] Step 2: Enrichment and separation of sulfur-containing ions based on foam separation technology 600, 700, 800, 900, 1000, 1100 mg / L of foam separation aid (modification ratio of 1:5) were respectively mixed with potassium persulfate degradation organic wastewater, the pH value was adjusted to 5.0, and injected into the foam separation tower 8 as feed liquid.

[0060] Foam separation tower 8 (such as Figure 2 The inner diameter R is 40 mm and the height H is 1000 mm. The foam separation is carried out at room temperature. The operation mode is intermittent operation. The gas velocity is 200 mL / min and the height of the foam layer is 700 mm. The ventilation is stopped when the foam cannot overflow from the top of the foam separation tower. The operation time is 30-45 min. The foam flowing out of the top of the tower is collected and mechanically defoamed, which is the defoaming liquid, and is injected into the defoaming liquid storage tank 11. The volumes of the defoaming liquid are 1.1, 1.6, 2.6, 3.3, 4.6 and 5.2% of the volume of the feed liquid, respectively. The sulfate ion concentrations are 7757.8, 8126.6, 8310.4, 8409.8, 8720.4 and 9280.8 mg / L, respectively, and the persulfate ion concentrations are 4512.8, 4667.9, 5055.5, 4513.2, 3230.7 and 2859.5, respectively. mg / L; the residual liquid discharged from the bottom of the foam separation tower was injected into the residual liquid storage tank 6, in which the sulfate ion concentrations were 419.2, 375.9, 291.5, 230.1, 103.6, and 18.3 mg / L, and the persulfate ion concentrations were 101.4, 76.5, 19.1, 1.1, 1.4, and 1.3 mg / L, respectively.

[0061] Figure 3 The figure shows the effect of different foam separation additive (GO-LS) concentrations on the removal rate and enrichment ratio of sulfur ions in the organic wastewater degraded by potassium persulfate using foam separation. Figure 3It can be seen that with the increase of the concentration of foam separation aid (GO-LS), the removal rate of sulfur-containing ions showed an upward trend, specifically, the removal rate of sulfate ions increased from 30.7% to 97.5%, and the removal rate of persulfate ions increased from 44.7% to 99.1%; while the enrichment ratio trend was opposite to the removal rate, specifically, the enrichment ratio of sulfate ions decreased from 29.7 to 7.8, and the enrichment ratio of persulfate ions decreased from 17.4 to 6.3. It can be seen that a lower concentration of foam separation aid (GO-LS) can achieve a higher enrichment of sulfur-containing ions, but is not conducive to the efficient separation of sulfur-containing ions; on the contrary, a higher concentration of foam separation aid (GO-LS) can achieve efficient separation of sulfur-containing ions, but is not conducive to the high enrichment of sulfur-containing ions. Considering that the removal rate and enrichment ratio of sulfur-containing ions are equally important to the foam separation effect, 1000 mg / L of foam separation aid (GO-LS) was selected as the appropriate concentration. At this time, the removal rate and enrichment ratio of sulfate ions were 98.7% and 17.3, respectively; the removal rate and enrichment ratio of persulfate ions were 95.0% and 12.4, respectively.

[0062] Example 2: Enrichment and separation of sulfur ions in organic wastewater from potassium persulfate degradation Step 1: Preparation of Foam Separation Agent (GO-LS) Graphene oxide prepared by Hummers oxidation method was dispersed in distilled water, and modifier (dodecylaminopropionic acid) was added at a mass ratio of 1:5. The pH value of the suspension was adjusted to 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, and 7.0. The suspension was stirred in a water bath at 85℃ for 3 h, centrifuged at 8000 r / min for 10 min, and the precipitate was collected, washed to neutrality, and dried at 60℃ to obtain a foam separation aid (GO-LS). The foam heights of the foam separation aid (GO-LS) with modified pH values ​​of 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, and 7.0 were 6, 10, 60, 130, 100, 70, and 40 mm, respectively. The foam half-lives were 1.5, 2.5, 12.0, 32.5, 25.0, 19.0, and 10.0 s, respectively.

[0063] Step 2: Enrichment and separation of sulfur-containing ions based on foam separation technology 1000 mg / L of foam separation aid (modified pH value is 4.0) is mixed with potassium persulfate degradation organic wastewater, and the pH value of the wastewater is adjusted to 3.0, 4.0, 5.0, 6.0, 7.0, and 8.0 respectively, and injected into the foam separation tower 8 as feed liquid; the foam separation tower 8 (such as Figure 2The inner diameter R is 40 mm and the height H is 1000 mm. The foam separation is carried out at room temperature. The operation mode is intermittent operation. The gas velocity is 200 mL / min and the foam layer height is 700 mm. The ventilation is stopped when the foam can no longer overflow from the top of the foam separation tower. The operation time is 30-45 min. The foam flowing out of the top of the tower is collected and mechanically defoamed, that is, the defoaming liquid, which is injected into the defoaming liquid storage tank 11. The volumes of the defoaming liquid are 4.6, 4.4, 4.8, 4.0, 3.8 and 3.2% of the volume of the feed liquid, respectively. The sulfate ion concentrations are 10683.2, 11105.6, 10161.5, 8906.8, 6770.2 and 5130.4 mg / L, respectively, and the persulfate ion concentrations are 3231.5, 3347.2, 3050.9, 2992.7, 2738.4 and 2082.1 mg / L, respectively. The residual liquid discharged from the bottom of the foam separation tower was injected into the residual liquid storage tank 6, wherein the sulfate ion concentrations were 9.0, 11.9, 12.9, 149.7, 252.3, and 346.9 mg / L, and the persulfate ion concentrations were 1.4, 2.8, 3.7, 31.6, 47.8, and 86.1 mg / L, respectively.

[0064] Figure 4 The figure shows the effect of different pH values ​​on the removal rate and enrichment ratio of sulfur ions in organic wastewater by foam separation of potassium persulfate. Figure 4 It can be seen that with the increase of pH value, the removal rate of sulfur-containing ions showed a decreasing trend, specifically, the removal rate of sulfate ions decreased from 98.2% to 32.8%, and the removal rate of persulfate ions increased from 99.0% to 44.3%; while the enrichment ratio showed a trend of first increasing and then decreasing with the increase of pH value, specifically, the enrichment ratio of sulfate ions first increased from 10.9 to 14.0, and then decreased to 8.0, and the enrichment ratio of persulfate ions first increased from 11.1 to 13.4, and then decreased to 6.4. It can be seen that a lower pH value can achieve efficient separation of sulfur-containing ions, but is not conducive to the enrichment of sulfur-containing ions; and a higher pH value is not conducive to the efficient separation and high enrichment of sulfur-containing ions. Taking into account the equal importance of the removal rate and enrichment ratio of sulfur-containing ions to the foam separation effect, pH 5.0 was selected as the pH value for foam separation of sulfur-containing ions in organic wastewater degradation by potassium persulfate. At this time, the removal rate and enrichment ratio of sulfate ions were 97.5% and 14.0, respectively; the removal rate and enrichment ratio of persulfate ions were 97.6% and 13.3, respectively.

[0065] Example 3: Enrichment and separation of sulfur ions in organic wastewater from potassium persulfate degradation Step 1: Preparation of Foam Separation Agent (GO-LS) Graphene oxide prepared by Hummers oxidation method was dispersed in distilled water, and a modifier (dodecylaminopropionic acid) was added at a mass ratio of 1:5. The pH value of the suspension was adjusted to 4.0, and the suspension was stirred for 3 h in a water bath at 85 °C. The suspension was centrifuged at 8000 r / min for 10 min, and the precipitate was collected, washed to neutrality, and dried at 60 °C to obtain a foam separation aid (GO-LS).

[0066] Step 2: Enrichment and separation of sulfur-containing ions based on foam separation technology 1000 mg / L of foam separation aid (GO-LS) was mixed with potassium persulfate degraded organic wastewater, and its pH value was adjusted to 5.0, and then injected into the foam separation tower 8 as feed liquid. Figure 2 The inner diameter R is 40 mm and the height H is 1000 mm. Foam separation is carried out at room temperature. The operation mode is intermittent operation. The gas velocity is 100, 200, 300, 400, and 500 mL / min. The height of the foam layer is 700 mm. Aeration is stopped when the foam cannot overflow from the top of the foam separation tower. The operation time is 20-60 min. The foam flowing out of the top of the tower is collected and mechanically defoamed, that is, the defoaming liquid, which is injected into the defoaming liquid storage tank 11. The volumes of the defoaming liquid are 3.4, 4.4, 6.0, 8.5, and 9.2% of the volume of the feed liquid, respectively. The sulfate ion concentrations are 13614.9, 11253.2, 8161.5, 5851.6, and 5374.5 mg / L, respectively, and the persulfate ion concentrations are 3873.6, 3253.9, 2345.4, 1692.3, and 1571.4 mg / L, respectively. The residual liquid discharged from the bottom of the foam separation tower was injected into the residual liquid storage tank 6, wherein the sulfate ion concentrations were 38.4, 5.1, 7.5, 5.4, and 6.1 mg / L, and the persulfate ion concentrations were 18.9, 7.1, 8.9, 7.5, and 6.0 mg / L, respectively.

[0067] Figure 5 The figure shows the effect of different gas velocities on the removal rate and enrichment ratio of sulfur ions in organic wastewater by foam separation with potassium persulfate. Figure 5It can be seen that with the increase of gas velocity, the removal rate of sulfur-containing ions showed a slow upward trend, specifically, the removal rate of sulfate ions increased from 95.5% to 98.8%, and the removal rate of persulfate ions increased from 92.8% to 99.1%; while the enrichment ratio showed a sharp downward trend with the increase of gas velocity, specifically, the enrichment ratio of sulfate ions decreased from 23.3 to 4.8, and the enrichment ratio of persulfate ions decreased from 16.2 to 3.1. It can be seen that a lower gas velocity can achieve a higher enrichment of sulfur-containing ions, but is not conducive to the efficient removal of sulfur-containing ions; on the contrary, a higher gas velocity can achieve an efficient removal of sulfur-containing ions, but is not conducive to a high enrichment of sulfur-containing ions. Considering that the removal rate and enrichment ratio of sulfur-containing ions are equally important to the foam separation effect, 200 mL / min was selected as the gas velocity for foam separation of sulfur-containing ions in organic wastewater degraded by potassium persulfate. At this time, the removal rate and enrichment ratio of sulfate ions were 96.5% and 17.5, respectively; the removal rate and enrichment ratio of persulfate ions were 95.4% and 14.2, respectively.

[0068] Example 4: Enrichment and separation of sulfur ions in organic wastewater from potassium persulfate degradation Step 1: Preparation of Foam Separation Agent (GO-LS) Graphene oxide prepared by Hummers oxidation method was dispersed in distilled water, and a modifier (dodecylaminopropionic acid) was added at a mass ratio of 1:5. The pH value of the suspension was adjusted to 4.0, and the suspension was stirred for 3 h in a water bath at 85 °C. The suspension was centrifuged at 8000 r / min for 10 min, and the precipitate was collected, washed to neutrality, and dried at 60 °C to obtain a foam separation aid (GO-LS).

[0069] Step 2: Enrichment and separation of sulfur-containing ions based on foam separation technology 1000 mg / L of foam separation aid (GO-LS) was mixed with potassium persulfate degradation organic wastewater, and the pH value was adjusted to 5.0, and then injected into the foam separation tower 8 as feed liquid; the foam separation tower 8 (such as Figure 2 The inner diameter R is 40 mm and the height H is 1000 mm. The foam separation is carried out at room temperature. The operation mode is intermittent operation. The gas velocity is 200 mL / min and the height of the foam layer is 700 mm. When the foam cannot overflow from the top of the foam separation tower, the ventilation is stopped. The operation time is 30-35 min. The foam flowing out of the top of the tower is collected and mechanically defoamed, which is the defoaming liquid, and injected into the defoaming liquid storage tank 11. The volume is 4.2% of the feed liquid volume, and the sulfate ion concentration is 11753.2 mg / L and the persulfate ion concentration is 3393.9 mg / L. The residual liquid discharged from the bottom of the foam separation tower is injected into the residual liquid storage tank 6, in which the sulfate ion concentration is 6.6 mg / L and the persulfate ion concentration is 7.8 mg / L.

[0070] Figure 6 The removal rate and enrichment ratio of sulfur ions in two organic wastewaters are shown in Figure 2. The removal rate and enrichment ratio of sulfate ions in organic wastewater degraded by potassium persulfate are 98.7% and 17.3% respectively through foam separation process; the removal rate and enrichment ratio of persulfate ions are 95.0% and 12.4% respectively. Figure 6 It can be seen that the prepared foam separation aid (GO-LS) has a good separation effect in enriching and separating sulfur-containing ions in persulfate and hydrogen persulfate degradation organic wastewater.

[0071] Comparative Example 1: Enrichment and separation of sulfur ions in organic wastewater by potassium persulfate degradation Step 1: Enrichment and separation of sulfur-containing ions based on foam separation technology 1000 mg / L of dodecylaminopropionic acid was mixed with potassium persulfate to degrade organic wastewater, and the pH value was adjusted to 5.0, and then injected into the foam separation tower 8 as the feed liquid. Figure 2 The inner diameter R is 40 mm and the height H is 1000 mm. The foam separation is carried out at room temperature. The operation mode is intermittent operation. The gas velocity is 200 mL / min and the height of the foam layer is 700 mm. When the foam cannot overflow from the top of the foam separation tower, the ventilation is stopped. The operation time is 75-90 min. The foam flowing out of the top of the tower is collected and mechanically defoamed, which is the defoaming liquid, and injected into the defoaming liquid storage tank 11. Its volume is 4.0% of the feed liquid volume, and its sulfate ion concentration is 3989.2 mg / L and the persulfate ion concentration is 1371.6 mg / L. The residual liquid discharged from the bottom of the foam separation tower is injected into the residual liquid storage tank 6, in which the sulfate ion concentration is 354.6 mg / L and the persulfate ion concentration is 98.8 mg / L.

[0072] Through the foam separation process, the removal rate and enrichment ratio of sulfate ions are 31.9% and 13.7 respectively; the removal rate and enrichment ratio of persulfate ions are 36.4% and 10.1 respectively. Figure 7 As shown in the figure, dodecylaminopropionic acid, as a common amphoteric surfactant, should have good foaming properties, but its poor solubility prevents it from being completely dissolved in the solution. In addition, the lack of carrier liquid leads to its weak capture ability. Therefore, the separation effect is much lower than that of the foam separation aid (GO-LS). Compared with the addition of the foam separation aid (GO-LS), the sulfate ion removal rate and enrichment ratio decreased by 64.6% and 3.8, respectively; the persulfate ion removal rate and enrichment ratio decreased by 59.0% and 4.1, respectively.

[0073] Comparative Example 2: Enrichment and separation of sulfur ions in organic wastewater from potassium persulfate degradation Step 1: Enrichment and separation of sulfur-containing ions based on foam separation technology 1000 mg / L of hexadecyltrimethylammonium bromide and potassium persulfate were mixed to adjust the pH value to 5.0 and injected into the foam separation tower 8 as feed liquid. Figure 2 The inner diameter R is 40 mm and the height H is 1000 mm. The foam separation is carried out at room temperature. The operation mode is intermittent operation. The gas velocity is 200 mL / min and the height of the foam layer is 700 mm. When the foam cannot overflow from the top of the foam separation tower, the ventilation is stopped. The operation time is 75-90 min. The foam flowing out of the top of the tower is collected and mechanically defoamed, which is the defoaming liquid, and injected into the defoaming liquid storage tank 11. Its volume is 74.0% of the feed liquid volume, and its sulfate ion concentration is 2788.2 mg / L and the persulfate ion concentration is 850.7 mg / L. The residual liquid discharged from the bottom of the foam separation tower is injected into the residual liquid storage tank 6, in which the sulfate ion concentration is 380.1 mg / L and the persulfate ion concentration is 121.2 mg / L.

[0074] Through the foam separation process, the removal rate and enrichment ratio of sulfate ions are 80.2% and 1.1 respectively; the removal rate and enrichment ratio of persulfate ions are 84.2% and 1.2 respectively. Figure 7 As shown in the figure, hexadecyltrimethylammonium bromide, as a common cationic surfactant, has good foaming property and foam stability. However, the lack of a collecting carrier makes its separation effect lower than that of the foam separation aid (GO-LS). Compared with the addition of the foam separation aid (GO-LS), the sulfate ion removal rate and enrichment ratio decreased by 16.3% and 16.4, respectively; the persulfate ion removal rate and enrichment ratio decreased by 11.2% and 13.0, respectively.

[0075] Comparative Example 3: Enrichment and separation of sulfur ions in organic wastewater from potassium persulfate degradation Step 1: Enrichment and separation of sulfur-containing ions based on foam separation technology 1000 mg / L sodium dodecyl sulfate and potassium persulfate degraded organic wastewater were mixed, the pH value was adjusted to 5.0, and injected into the foam separation tower 8 as feed liquid; the foam separation tower 8 (such as Figure 2The inner diameter R is 40 mm and the height H is 1000 mm. The foam separation is carried out at room temperature. The operation mode is intermittent operation. The gas velocity is 200 mL / min and the height of the foam layer is 700 mm. When the foam cannot overflow from the top of the foam separation tower, the ventilation is stopped. The operation time is 75-90 min. The foam flowing out of the top of the tower is collected and mechanically defoamed, which is the defoaming liquid, and injected into the defoaming liquid storage tank 11. Its volume is 80.0% of the feed liquid volume, and its sulfate ion concentration is 652.2 mg / L and the persulfate ion concentration is 315.8 mg / L. The residual liquid discharged from the bottom of the foam separation tower is injected into the residual liquid storage tank 6, in which the sulfate ion concentration is 557.7 mg / L and the persulfate ion concentration is 205.2 mg / L.

[0076] Through the foam separation process, the removal rate and enrichment ratio of sulfate ions are 77.6% and 0.97 respectively; the removal rate and enrichment ratio of persulfate ions are 79.4% and 1.1 respectively. Figure 7 As shown in the figure, sodium dodecyl sulfate, as a common anionic surfactant, has good foaming properties and foam stability, but the enhanced electrostatic repulsion and lack of capture carriers make its separation effect far lower than that of the foam separation aid (GO-LS). Compared with the addition of the foam separation aid (GO-LS), the sulfate ion removal rate and enrichment ratio decreased by 18.9% and 16.5, respectively; the persulfate ion removal rate and enrichment ratio decreased by 16.0% and 13.1, respectively.

Claims

1. A foam separation aid, characterized in that: The invention comprises graphene oxide and a modifier, wherein the mass ratio of the two is 1:1 to 1:6; the modifier is selected from sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide, dodecyldimethyl betaine, cocoamidopropyl betaine, dodecylaminopropionic acid or sodium dodecylaminopropionate.

2. The foam separation aid according to claim 1, characterized in that The mass ratio of graphene oxide to modifier is 1:

5.

3. The method for preparing the foam separation aid according to claim 1 or 2, characterized in that: include: Step 1, dispersing graphene oxide in distilled water, and adding a modifier in proportion to obtain a suspension; Step 2: Adjust the pH of the suspension to 1.0-8.0, stir in a water bath at 75-95° C. until the reaction is complete, and obtain a foam separation aid (GO-LS) after centrifugation, washing, and drying.

4. A foam separation method for separating and enriching sulfur ions in water, characterized in that: include: Step 1, preparation of feed liquid; Adding the foam separation aid (GO-LS) according to claim 1 or 2 to the liquid to be separated to form a feed liquid, and then adjusting the pH value of the feed liquid to 3.0-6.0; Step 2, foam separation; Injecting the feed liquid obtained in step 1 into a foam separation tower for foam separation, collecting the foam and defoaming the foam to obtain a defoaming liquid; Step 3, adjusting the pH value of the defoaming solution to neutral and then settling to obtain a supernatant and a sediment; The supernatant is used as the raw material for producing sulfate, and the sediment is mixed with the liquid to be separated and sent to the foam separation tower for recycling.

5. The method according to claim 4, characterized in that In step 1, the liquid to be separated is organic wastewater degraded by persulfate, including one or more combinations of organic wastewater degraded by potassium hydrogen persulfate, organic wastewater degraded by potassium persulfate, and organic wastewater degraded by ammonium persulfate.

6. The method according to claim 4 or 5, characterized in that: In step 1, a foam separation aid (GO-LS) is added to the liquid to be separated at a concentration of 100-1200 mg / L.

7. The method according to claim 6, characterized in that Add foam separation aid (GO-LS) to the liquid to be separated at a concentration of 600~1100 mg / L.

8. The method according to claim 4 or 7, characterized in that: In step 1, the pH value of the feed solution is adjusted to 4.0-5.

0.

9. The method according to claim 8, characterized in that: A gas distributor is arranged at the bottom of the foam separation tower. The gas distributor, the air humidifying bottle, the buffer bottle and the air compressor are connected in sequence through pipelines to input gas into the foam separation tower.

10. The method according to claim 4 or 9, characterized in that: In step 2, foam separation is performed at room temperature with a gas velocity of 100-600 mL / min and a foam layer height of 3 / 5-4 / 5 of the height of the foam separation tower, and the foam overflowing the top of the tower is collected.

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