A froth flotation method for removing rhodamine B in wastewater based on Janus nano flotation agent

Abstract

The application provides a foam flotation method for removing rhodamine B in water, comprising the following steps: preparing amphiphilic Janus nanosilica particles, and taking the Janus nanosilica particles as a flotation agent to perform foam flotation. The flotation agent generates stable foam in the process of foam flotation, and effectively captures rhodamine B, so that the purpose of removing rhodamine B in water is achieved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a foam flotation method for removing Rhodamine B from wastewater based on Janus nanoflotation agent. Background Technology

[0002] The production and use of dyes generate large amounts of wastewater, most of which contains synthetic dyes with complex aromatic ring structures. These dyes are highly stable, difficult to biodegrade, and often exhibit carcinogenic, teratogenic, and mutagenic effects, resulting in significant biotoxicity. Therefore, the control of dye wastewater pollution has always been an important issue in environmental protection.

[0003] Currently, the main methods for removing Rhodamine B from water include adsorption, Fenton oxidation, ion exchange, and electrocatalysis. However, these methods have certain drawbacks, such as complex processes, high costs, and the potential for secondary pollution. Therefore, finding a green, environmentally friendly, and cost-effective method to replace traditional processes for removing Rhodamine B from water is a major challenge facing society today, and it is precisely what scientists are relentlessly pursuing.

[0004] Janus particles, also known as bifacial particles, possess a non-centrosymmetric structure. They have attracted much attention due to their surfaces having two or more different chemical compositions. They can be obtained by modifying inorganic or organic materials as templates, and different modifying groups can give them different functions. They are widely used in cancer treatment, sensors, catalysts, and drug carriers. Summary of the Invention

[0005] To address the problems of existing technologies, this application uses hydrophilic nano-SiO2 as a template to prepare amphiphilic Janus nano-silica particles by grafting hydrophobic alkyl groups with chain lengths of 12-18. These particles are then used as flotation agents for Rhodamine B in foam flotation. The hydrophilic side captures the dye in the wastewater, while the hydrophobic side allows it to adsorb onto bubbles and be enriched as the foam rises. It exhibits good foam stability, high Rhodamine B capture efficiency, and can efficiently remove dye from wastewater without the addition of any surfactant. In particular, compared with the commonly used surfactant CTAB in existing technologies, under the same conditions, the removal rate is nearly 3 times higher, and the enrichment ratio is 3.5 times higher. Even compared with SDS, which is recognized as having the best effect, the enrichment ratio is more than 2 times higher. The specific technical solution is as follows:

[0006] In a first aspect, the present invention provides a foam flotation method for removing Rhodamine B from water, the foam flotation method comprising using amphiphilic Janus nano silica particles as a flotation agent to perform foam flotation.

[0007] The foam flotation method involves mixing an aqueous solution containing Rhodamine B with amphiphilic Janus nano silica particles and injecting the mixture as feed into a foam flotation tower for aeration and foam flotation.

[0008] Preferably, the pH of the feed solution is 5-9, such as 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5 or 9, preferably 6-8, and more preferably 6-7.

[0009] Preferably, the concentration of amphiphilic Janus nano silica particles in the feed liquid is 25-150 mg / L, for example 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 90, 100, 110, 120, 130, 140 or 150 mg / L, more preferably 25-100 mg / L, and even more preferably 50-75 mg / L.

[0010] Preferably, the concentration of Rhodamine B in the feed solution is 1-100 mg / L, more preferably 5-20 mg / L.

[0011] The aqueous solution containing Rhodamine B is wastewater, such as wastewater from the dye production process.

[0012] The mass ratio of Rhodamine B to amphiphilic Janus nano silica particles is (0.05-0.8):1, preferably (0.1-0.4):1, and even more preferably (0.1-0.2):1.

[0013] Preferably, the amphiphilic Janus nano silica particles are wetted with ethanol (preferably anhydrous ethanol) and then mixed with an aqueous solution containing Rhodamine B.

[0014] Preferably, the ventilation rate is 200-700 mL / min, such as 200, 300, 350, 400, 450, 500, 550, 600 or 700 mL / min, preferably 400-600 mL / min.

[0015] Preferably, the gas introduced can be air or an inert gas (e.g., nitrogen).

[0016] The gas is preferably blown in from the lower middle part of the foam flotation tower, and more preferably from the bottom.

[0017] The foam flotation tower can be selected from towers commonly used in the prior art.

[0018] Preferably, the cross-section of the foam flotation tower can be circular, elliptical, prismatic, square, triangular, pentagonal, hexagonal, heptagonal, octagonal, or irregular in shape.

[0019] Preferably, the foam flotation tower can have the same or different inner diameters in the height direction, and its column height and inner diameter can be adjusted according to conventional use. Components can also be added to the foam flotation tower, such as devices to enhance foam drainage, devices to stabilize foam, etc.

[0020] In some specific embodiments, the foam flotation tower is a hollow cylinder with a height-to-diameter ratio of 10-35:1, preferably 20-30:1.

[0021] Preferably, the feed liquid volume is 1 / 10-9 / 10 of the height of the foam flotation tower, more preferably 2 / 5-4 / 5, and even more preferably 2 / 5-3 / 5.

[0022] The amphiphilic Janus nano silica particles are grafted with hydrophobic alkyl groups with chain lengths of 12-18 (e.g., 12, 14, 16 or 18) using hydrophilic nano SiO2 as a template.

[0023] The amphiphilic Janus nano-silica particles were prepared by an interface masking method.

[0024] Preferably, the preparation method of the amphiphilic Janus nano silica particles includes: wetting hydrophilic nano SiO2 with water, then dispersing it in an organic solvent, and then adding an alkylsilane coupling agent to carry out the reaction.

[0025] In this process, the organic solvent and water work together to disperse the hydrophilic nano-silica at the liquid-liquid interface between the water and the organic phase. Then, an alkylsilane coupling agent is added to the organic phase, causing the nano-silica to react with the alkylsilane coupling agent on one side of the organic phase.

[0026] The mass ratio of hydrophilic nano-silica particles to water is 1:1-5:1.

[0027] Preferably, dispersion is performed after adding an alkylsilane coupling agent.

[0028] Preferably, the hydrophilic nano-silica particles react with an alkylsilane coupling agent under the action of a catalyst. The catalyst is, for example, triethylamine.

[0029] Preferably, the reaction is carried out under stirring conditions. The stirring time is preferably 10-60 min, for example 20-40 min.

[0030] Preferably, the method for preparing amphiphilic Janus silica particles further includes washing and drying.

[0031] In some specific embodiments, the organic solvent includes at least one of benzene, toluene, cyclohexane, or cyclohexanone.

[0032] Preferably, the alkyl chain length of the alkylsilane coupling agent is selected from 12-18 (e.g., 12, 14, 16, 18), such as octadecyltrimethoxysilane, octadecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, n-dodecyltrimethoxysilane or n-dodecyltriethoxysilane.

[0033] Preferably, the molar ratio of hydrophilic nano-SiO2 to alkylsilane coupling agent is 5:1-50:1, for example (5, 10, 15, 20, 25, 30, 35, 40, 45 or 50):1, preferably 8:1-14:1.

[0034] The amount of alkylsilane coupling agent added is 0.01-0.08 mol / L, for example 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07 or 0.08 mol / L; preferably 0.02-0.05 mol / L.

[0035] The hydrophilic nano-silica was prepared using the Stober method.

[0036] The diameter of nano-silica can be 100-1000 nm.

[0037] In some specific embodiments, the preparation method of the amphiphilic Janus nano silica particles includes: grinding hydrophilic nano SiO2 into powder, wetting it with water, and then dispersing it in an organic solvent with a concentration of 20-30 g / L, and then adding 0.01-0.08 mol / L of hexadecyltrimethoxysilane, and reacting it under the catalysis of triethylamine.

[0038] In some specific embodiments, the foam flotation method includes:

[0039] (1) Preparation of amphiphilic Janus nano silica particles;

[0040] (2) Mix the aqueous solution containing Rhodamine B with amphiphilic Janus nano silica particles and adjust the pH to 5-9 to use as the feed solution;

[0041] (3) Inject the feed liquid into the foam flotation tower and ventilate at a gas velocity of 200-700 mL / min to carry out foam flotation. Collect the foam from the top of the foam flotation tower. Stop ventilating when the foam can no longer flow out from the top of the foam flotation tower, and the foam flotation ends.

[0042] In a second aspect, the present invention provides a method for preparing amphiphilic Janus nano-silica particles, the method comprising wetting hydrophilic nano-SiO2 with water, dispersing it in an organic solvent, and then adding an alkylsilane coupling agent to carry out the reaction.

[0043] Preferably, the alkyl chain length of the alkylsilane coupling agent is selected from 12-18 (e.g., 12, 14, 16, 18), for example selected from octadecyltrimethoxysilane, octadecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, n-dodecyltrimethoxysilane or n-dodecyltriethoxysilane.

[0044] Preferably, the molar ratio of hydrophilic nano-SiO2 to alkylsilane coupling agent is 5:1-50:1, for example (5, 10, 15, 20, 25, 30, 35, 40, 45 or 50):1, preferably 8:1-14:1.

[0045] Preferably, the concentration of hydrophilic nano-SiO2 is 20-30 g / L.

[0046] Preferably, the amount of alkylsilane coupling agent added is 0.01-0.08 mol / L; more preferably 0.02-0.05 mol / L.

[0047] The amphiphilic Janus nano-silica particles are spherical in shape.

[0048] A third aspect of the present invention provides amphiphilic Janus nano-silica particles obtained by the above preparation method.

[0049] In a fourth aspect, the present invention provides the application of amphiphilic Janus nano-silica particles in the removal of Rhodamine B from wastewater.

[0050] The beneficial effects of this invention are:

[0051] (1) Based on the principle of foam flotation, this invention uses the prepared amphiphilic Janus nano silica particles as nano flotation agents to capture Rhodamine B dye in wastewater. By bubbling, a large number of gas-liquid interfaces are generated. The hydrophobic and oleophilic side of the surface of the amphiphilic Janus nano silica particles can easily adhere to the gas-liquid interface and float up with the bubbles. Finally, the surface foam is removed by foam flotation to reduce the concentration of Rhodamine B dye in wastewater.

[0052] (2) In view of the shortcomings of the prior art, the present invention develops a process for removing dyes from wastewater by foam flotation based on amphiphilic Janus nano silica particles. The nano flotation agent is used to capture dyes during the air flotation process, which effectively improves the removal rate of dyes from wastewater.

[0053] (3) This process utilizes the amphiphilicity of Janus nano flotation agent, using the hydrophilic surface to capture Rhodamine B in wastewater, and the hydrophobic surface to easily attach bubbles. As the bubbles rise, the dye in the wastewater is discharged through the foam phase.

[0054] (4) The equipment and process flow used in this process are simple, the treatment effect is good, the operating cost is low, and it lays a good foundation for the removal and recovery of dyes in wastewater, which is conducive to large-scale promotion and application. Attached Figure Description

[0055] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:

[0056] Figure 1 Schematic diagram of a foam flotation device, wherein 1-electromagnetic air pump; 2-gas buffer bottle; 3-gas wetting bottle; 4-flow regulator; 5-water stop clamp; 6-gas distributor; 7-foam flotation tower; 8-foam collection tank.

[0057] Figure 2 The effect of hexadecyltrimethoxysilane concentration on foam height and half-life.

[0058] Figure 3 The effect of hexadecyltrimethoxysilane concentration on surface tension.

[0059] Figure 4 Effect of hexadecyltrimethoxysilane concentration on average foam diameter.

[0060] Figure 5 Effects of different concentrations of JSP on the removal rate, enrichment ratio, adsorption density, and liquid holdup of Rhodamine B in foam flotation (a).

[0061] Figure 6 Effects of different pH values ​​on the removal rate, enrichment ratio, adsorption density, and liquid holdup of Rhodamine B by foam flotation (a).

[0062] Figure 7 Effects of different gas velocities on the removal rate, enrichment ratio, adsorption density, and liquid holdup of Rhodamine B in foam flotation (a). Detailed Implementation

[0063] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] Unless otherwise defined, all scientific and technical terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art.

[0065] All publications, patents and published patent specifications cited in this application are incorporated herein by reference in their entirety.

[0066] Unless otherwise specified, all materials used in the embodiments of this invention are commercially available.

[0067] Unless otherwise specified, the parts, percentages, or proportions mentioned in the embodiments of this invention are based on mass.

[0068] In this embodiment, the hydrophilic silica nanoparticles were prepared using the Stober method. Specifically, 9 mL of ammonia, 179 mL of ethanol, and 62 mL of deionized water were added to a 500 mL Erlenmeyer flask and mixed thoroughly. Then, 15.9 mL of tetraethyl orthosilicate was added. The mixture was shaken in a constant-temperature shaker at 30°C and 120 rpm for 2 hours to form a white product. These products were collected by centrifugation (8000 rpm, 6 min), redispersed in anhydrous ethanol, washed, and centrifuged again; this step was repeated 5 times. The final precipitate was dried under vacuum at 373 K to obtain the hydrophilic silica nanoparticles.

[0069] The formulas for calculating the removal rate R, enrichment ratio E, liquid holdup ε, and adsorption density Γ in this application are as follows:

[0070]

[0071] In equations (1, 2), C0, C f C r (mg / L) represent the concentrations of Rhodamine B in the feed solution, foam solution, and residual solution, respectively.

[0072] Q0,Q f Q r (mL / min) represent the volumetric flow rates of the feed liquid, foam liquid, and residual liquid, respectively.

[0073] In formula (3), Γ(mg / m 2 ) represents surface excess; Φ (mg / s) represents adsorption mass flux; C f (mg / m 3 ) and C e (mg / m 3 Q represents the concentration of Rhodamine B in the foam solution and the liquid phase, respectively. f (mL / min) is the volumetric flow rate of the foam liquid, A(m 2 / s) represents the surface area flux of the bubbles;

[0074] In equation (4), Q0, Q r Q g (mL / min) represents the volumetric flow rate of the feed liquid, the volumetric flow rate of the residual liquid, and the gas velocity, respectively.

[0075] The foam flotation device used in the embodiments is shown in [reference needed]. Figure 1During operation, the feed liquid is transferred to the foam flotation tower 7, the switch 1 of the electromagnetic air pump and the water stop clamp 5 are turned on, and the gas passes through the gas buffer bottle 2 and the gas wetting bottle 3 and is bubbled into the foam flotation tower 7 through the gas distributor 6. The gas velocity is adjusted to a certain value by the rotor flow meter 4 for flotation. When foam begins to emerge from the top of the foam flotation tower, the discharged foam is collected into the foam collection tank 8. When no new foam is generated, the water stop clamp 5 is clamped, the electromagnetic air pump 1 is turned off to stop the air supply, and the flotation ends.

[0076] Example 1

[0077] (1) Preparation of amphiphilic Janus nano-silica particles

[0078] Hydrophilic nano-silica particles were ground into a fine, uniform powder. 2.5 g of the powder was placed in a 100 mL beaker and moistened with 0.3 mL of deionized water. Then, 40 mL of benzene was added, and the mixture was thoroughly dispersed using a homogenizer at 10,000 rpm. Next, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, and 0.08 mol / L of hexadecyltrimethoxysilane were added, and the mixture was further dispersed using a homogenizer for 2 min. Then, 0.5 mL of triethylamine was added to catalyze the reaction, and the mixture was stirred for another 30 min. The obtained product was centrifuged and washed twice with anhydrous ethanol. The final product was then vacuum-dried at 373 K to obtain amphiphilic Janus nano-silica particles (JSP).

[0079] (2) Study on the foam properties of amphiphilic Janus nano silica particles

[0080] Add 0.15g of JSP powder obtained by the above method to a 500mL beaker, add 1mL of anhydrous ethanol to wet the JSP, add 300mL of deionized water, and place the beaker in an ultrasonic cleaner and ultrasonically vibrate for 15min to make the JSP evenly distributed in the solution.

[0081] ① Determination of foam height and half-life

[0082] use Figure 1 The foam flotation apparatus shown measures the foam height H of the solution. f and half-life T 1 / 2 First, pour 300 mL of the solution prepared above into the froth flotation tower. Turn on the electromagnetic air pump and the stop valve to bubble the froth flotation tower. Adjust the air velocity to 600 mL / min using a rotor flow meter, and bubble for 1 minute. Record the height H of the foam generated by the JSP solution. f Take a picture of the foam layer, then clamp the water-stopping clip, turn off the electromagnetic air pump, and record the time T required for half of the foam to disappear. 1 / 2These two data points are used to characterize the foaming properties and foam stability of the JSP solution.

[0083] See results Figure 2 As shown, with the increase of hexadecyltrimethoxysilane concentration, both foam height and half-life show a trend of first increasing and then decreasing. When the concentration of hexadecyltrimethoxysilane is 0.01-0.05 mol / L, the foam height and half-life are better.

[0084] ② Surface tension measurement and procedures

[0085] The surface tension of the JSP solution was measured using a surface tension meter. First, the measuring dish was thoroughly cleaned. The measuring plate was then heated with the outer flame of an alcohol lamp until it turned reddish, and after cooling, it was used. The solution to be tested was placed on the sample stage, and the test was conducted. Once the data remained constant, recording was stopped, the platform stopped, and the surface tension meter reading was recorded. The platform then descended, and the measurement was repeated several times, with data recorded.

[0086] See results Figure 3 As shown, the surface tension initially decreases with increasing concentration of hexadecyltrimethoxysilane, remaining between 71.5 mN / m and 74.5 mN / m.

[0087] ③ Measurement of average foam diameter

[0088] The bubble diameter d was obtained by taking pictures of the foam layer with a camera, processing the pictures with the software Nano Measurer 1.2, randomly selecting 200 bubbles, and calculating the average bubble diameter d of the bubbles in the foam layer.

[0089] See results Figure 4 As shown, the foam diameter increases with increasing concentration of hexadecyltrimethoxysilane. This indicates that low concentrations of hexadecyltrimethoxysilane are beneficial for foam stability and reduce foam diameter; excessively high concentrations of hexadecyltrimethoxysilane lead to over-alkylation of particles, which is detrimental to foam stability, increases foam diameter, and accelerates foam breakage. Therefore, the bubble diameter is best when it is between 1.25 and 1.35 mm, at which point the concentration of hexadecyltrimethoxysilane is 0.02-0.06 mol / L.

[0090] Based on the comprehensive foam performance study results, when the concentration of hexadecyltrimethoxysilane is 0.02-0.05 mol / L, the foam exhibits good stability and suitable surface tension.

[0091] Example 2

[0092] (1) Preparation of amphiphilic Janus nano-silica particles

[0093] Hydrophilic nano-silica particles were ground into a fine, uniform powder. 2.5 g of the powder was placed in a 100 mL beaker and moistened with 0.3 mL of deionized water. Then, 40 mL of benzene was added, and the mixture was thoroughly dispersed using a homogenizer at 10,000 rpm. Next, 0.04 mol / L of hexadecyltrimethoxysilane was added, and the mixture was further dispersed using a homogenizer for 2 min. Then, 0.5 mL of triethylamine was added to catalyze the reaction, and the mixture was stirred for another 30 min. The obtained product was centrifuged and washed twice with anhydrous ethanol. The final product was then vacuum-dried at 373 K to obtain amphiphilic Janus nano-silica particles (JSP).

[0094] (2) Wet the JSP prepared in (1) with anhydrous ethanol, add Rhodamine B and water, and prepare solutions with Rhodamine B concentration of 10 mg / L and JSP concentrations of 0, 25, 50, 75, 100, 125 and 150 mg / L respectively. Place the solutions in an ultrasonic cleaner and shake for 15 min.

[0095] (3) Adjust the pH value to 7.0 as the feed liquid.

[0096] (4) Add feed liquid to 2 / 5 of the height of the froth flotation tower, then turn on the electromagnetic air pump and the stop valve to bubble the froth flotation tower. Adjust the air velocity to 600 mL / min using a rotor flow meter. Then, continuously pump the feed liquid into the froth flotation tower near the foam-solution interface using a feed pump. Slowly discharge a large amount of solution from the bottom of the froth flotation tower. By adjusting the feed rate of the feed liquid and the discharge rate of the bulk solution, the foam-solution interface can be kept at a constant position. When the foam-solution interface remains at a fixed position for 20 minutes, the operating system reaches a steady state, and a sample is taken. Install a foam collector at the top of the froth flotation tower to collect and defoam until no new foam is generated. Then, clamp the stop valve, turn off the electromagnetic air pump, and stop flotation. Measure the volume of the residual liquid after froth flotation and take a sample. Place the sample to be tested in a high-speed centrifuge and centrifuge at 8000 rpm / min for 15 minutes to obtain the supernatant.

[0097] (5) Using deionized water as a blank control at 554 nm, the absorbance was measured to obtain the concentration of Rhodamine B, and the removal rate R, enrichment ratio E, liquid holdup ε and adsorption density Γ were calculated.

[0098] The results showed that without JSP (concentration of 0), Rhodamine B could not be floated, and the removal rate was 0%. The results were similar for concentrations of 25-150 mg / L. Figure 5 As shown, when the JSP concentration is 25-100 mg / L, the removal rate R, enrichment ratio E, liquid holdup ε, and adsorption density Γ are all relatively good.

[0099] Example 3

[0100] (1) Preparation of amphiphilic Janus nano silica particles: Same as in Example 2.

[0101] (2) Wet the JSP prepared in (1) with anhydrous ethanol, add Rhodamine B and water, and prepare a solution with Rhodamine B concentration of 10 mg / L and JSP concentration of 50 mg / L. Place the solution in an ultrasonic cleaner and shake for 15 min.

[0102] (3) Adjust the pH value to 5.0, 6.0, 7.0, 8.0, or 9.0 as the feed solution.

[0103] (4) Add feed liquid to half the height of the froth flotation tower, then turn on the electromagnetic air pump and the stop valve to bubble the froth flotation tower. Adjust the air velocity to 600 mL / min using a rotor flow meter. Then, continuously pump the feed liquid into the froth flotation tower near the foam-solution interface using a feed pump. Slowly discharge a large amount of solution from the bottom of the froth flotation tower. By adjusting the feed rate of the feed liquid and the discharge rate of the bulk solution, the foam-solution interface can be kept at a constant position. When the foam-solution interface remains at a fixed position for 20 minutes, the operating system reaches steady state, and a sample is taken. Install a foam collector at the top of the froth flotation tower to collect and defoam. When no new foam is generated, clamp the stop valve, turn off the electromagnetic air pump, and stop flotation. Measure the volume of the residual liquid after froth flotation and take a sample. Place the sample in a high-speed centrifuge and centrifuge at 8000 rpm / min for 15 minutes to obtain the supernatant.

[0104] (5) Using deionized water as a blank control at 554 nm, the absorbance was measured to obtain the concentration of Rhodamine B, and the enrichment ratio E, removal rate R, liquid holdup ε and adsorption density Γ were calculated.

[0105] The results are as follows Figure 6 As shown, when the pH of the feed solution is 6-8, the removal rate R, enrichment ratio E, liquid holdup ε, and adsorption density Γ are all better.

[0106] Example 4

[0107] (1) Preparation of amphiphilic Janus nano silica particles: Same as in Example 2.

[0108] (2) Wet the JSP prepared in (1) with anhydrous ethanol, add Rhodamine B and water, and prepare a solution with the concentration of Rhodamine B of 10 mg / L and the concentration of JSP of 50 mg / L. Place the solution in an ultrasonic cleaner and shake for 15 min.

[0109] (3) Adjust the pH value to 7.0 as the feed liquid.

[0110] (4) Add feed liquid to 3 / 5 of the height of the froth flotation tower, then turn on the electromagnetic air pump and the stop valve to bubble the froth flotation tower. Adjust the air velocity to 200, 300, 400, 500, 600, or 700 mL / min using a rotor flow meter. Then, continuously pump the feed liquid into the froth flotation tower near the foam-solution interface using a feed pump. Slowly discharge a large amount of solution from the bottom of the froth flotation tower. By adjusting the feed rate of the feed liquid and the discharge rate of the bulk solution, the foam-solution interface can be kept at a constant position. When the foam-solution interface remains at a fixed position for 20 minutes, the operating system reaches steady state, and a sample is taken. Install a foam collector at the top of the froth flotation tower to collect and defoam. When no new foam is generated, clamp the stop valve, turn off the electromagnetic air pump, and stop flotation. Measure the volume of the residual liquid after froth flotation and take a sample. The sample to be tested was placed in a high-speed centrifuge and centrifuged at 8000 rpm for 15 minutes to obtain the supernatant.

[0111] (5) Using deionized water as a blank control at 554 nm, the absorbance was measured to obtain the concentration of Rhodamine B, and the removal rate R, enrichment ratio E, liquid holdup ε and adsorption density Γ were calculated.

[0112] The results are as follows Figure 7 As shown, when the flotation gas velocity is 400-600 mL / min, the removal rate R, enrichment ratio E, liquid holdup ε, and adsorption density Γ are all relatively good.

[0113] Example 5

[0114] (1) Preparation of amphiphilic Janus nano silica particles: Same as in Example 2.

[0115] (2) Wet the JSP prepared in (1) with anhydrous ethanol, add Rhodamine B and water, and in the prepared solution, the concentration of Rhodamine B is 10 mg / L and the concentration of JSP is 50-75 mg / L. Place it in an ultrasonic cleaner and shake for 15 min.

[0116] (3) Adjust the pH value to 6.0-7.0 as the feed solution.

[0117] (4) Add feed liquid to half the height of the froth flotation tower, then turn on the electromagnetic air pump and the stop valve to bubble the froth flotation tower. Adjust the air velocity to 400-600 mL / min using a rotor flow meter. Then, continuously pump the feed liquid into the froth flotation tower near the foam-solution interface using a feed pump. Slowly discharge a large amount of solution from the bottom of the froth flotation tower. By adjusting the feed rate of the feed liquid and the discharge rate of the bulk solution, the foam-solution interface can be kept at a constant position. When the foam-solution interface remains at a fixed position for 20 minutes, the operating system reaches steady state, and a sample is taken. Install a foam collector at the top of the froth flotation tower to collect and defoam. When no new foam is generated, clamp the stop valve, turn off the electromagnetic air pump, and stop flotation. Measure the volume of the residual liquid after froth flotation and take a sample. Place the sample in a high-speed centrifuge and centrifuge at 8000 rpm / min for 15 minutes to obtain the supernatant.

[0118] (5) The absorbance was measured at 554 nm using deionized water as a blank control to obtain the concentration of Rhodamine B. The removal rate R, enrichment ratio E, liquid holdup ε and adsorption density Γ were calculated. The results are shown in Table 1.

[0119] Table 1

[0120]

[0121] Example 6

[0122] The Janus nanoflotation agent (JSP) prepared in Example 2 and a traditional surfactant were used to remove Rhodamine B, and their effects were compared.

[0123] 1. Steps

[0124] Janus nanoflotation agent for the removal of Rhodamine B

[0125] (1) Wet the prepared JSP with anhydrous ethanol, add Rhodamine B and water, and prepare a solution with Rhodamine B concentration of 10 mg / L and JSP concentration of 50 mg / L. Place the solution in an ultrasonic cleaner and shake for 15 min.

[0126] (2) Adjust the pH value to 7.0 as the feed liquid.

[0127] (3) Add feed liquid to half the height of the froth flotation tower, then turn on the electromagnetic air pump and the stop valve to bubble the froth flotation tower. Adjust the air velocity to 500 mL / min using a rotor flow meter. Then, continuously pump the feed liquid into the froth flotation tower near the foam-solution interface using a feed pump. Slowly discharge a large amount of solution from the bottom of the froth flotation tower. By adjusting the feed rate of the feed liquid and the discharge rate of the bulk solution, the foam-solution interface can be kept at a constant position. When the foam-solution interface remains at a fixed position for 20 minutes, the operating system reaches steady state, and a sample is taken. Install a foam collector at the top of the froth flotation tower to collect and defoam. When no new foam is generated, clamp the stop valve, turn off the electromagnetic air pump, and stop flotation. Measure the volume of the residual liquid after froth flotation and take a sample.

[0128] Removal of Rhodamine B by Chemical Surfactants

[0129] SDS:

[0130] (1) Sodium dodecyl sulfate (SDS), rhodamine B and water were mixed to prepare a solution with an SDS concentration of 50 mg / L and a rhodamine B concentration of 10 mg / L. The solution was placed in an ultrasonic cleaner and shaken for 15 min. Steps (2) and (3) were the same as those for removing (2) and (3) from rhodamine B using Janus nanoflotation agent.

[0131] CTAB:

[0132] (1) Mix hexadecyltrimethylammonium bromide (CTAB), rhodamine B and water to prepare a solution with a CTAB concentration of 50 mg / L and a rhodamine B concentration of 10 mg / L. Place the solution in an ultrasonic cleaner and shake for 15 min. Steps (2) and (3) are the same as those for removing (2) and (3) from rhodamine B using Janus nanoflotation agent.

[0133] 2. Testing

[0134] Using deionized water as a blank control, absorbance was measured at 554 nm to obtain the concentration of Rhodamine B, and the removal rate R, enrichment ratio E, liquid holdup ε, and adsorption density Γ were calculated.

[0135] 3. Results

[0136] The results are shown in Table 2. Under the same conditions, the JSP prepared in this application has a similar removal rate to traditional SDS, but the enrichment ratio is more than twice that of SDS.

[0137] Table 2

[0138]

[0139] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0140] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A foam flotation method for removing Rhodamine B from water, characterized in that, The foam flotation method described herein includes using amphiphilic Janus nano silica particles as a flotation agent to perform foam flotation; The preparation method of the amphiphilic Janus nano silica particles includes: wetting hydrophilic nano SiO2 with water, then dispersing it in an organic solvent, and then adding an alkylsilane coupling agent to react and obtain amphiphilic Janus nano silica particles. The molar ratio of hydrophilic nano-SiO2 to alkylsilane coupling agent is 8:1-14:1; The alkyl chain length of the alkylsilane coupling agent is selected from 12-18.

2. The foam flotation method according to claim 1, characterized in that, The foam flotation method involves mixing an aqueous solution containing Rhodamine B with amphiphilic Janus nano silica particles and injecting the mixture as feed into a foam flotation tower for aeration and foam flotation.

3. The foam flotation method according to claim 2, characterized in that, The pH of the feed solution is 5-9.

4. The foam flotation method according to claim 3, characterized in that, The pH of the feed solution is 6-8.

5. The foam flotation method according to claim 2, characterized in that, The concentration of amphiphilic Janus nano silica particles in the feed liquid is 25-150 mg / L.

6. The foam flotation method according to claim 5, characterized in that, The concentration of amphiphilic Janus nano silica particles in the feed liquid is 25-100 mg / L.

7. The foam flotation method according to claim 2, characterized in that, The ventilation rate is 200-700 mL / min.

8. The foam flotation method according to claim 7, characterized in that, The ventilation rate is 400-600 mL / min.

9. The foam flotation method according to claim 1, characterized in that, The alkylsilane coupling agent is selected from octadecyltrimethoxysilane, octadecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, n-dodecyltrimethoxysilane, or n-dodecyltriethoxysilane.

10. The foam flotation method according to any one of claims 1-9, characterized in that, The amount of alkylsilane coupling agent added is 0.02-0.05 mol / L.

11. The foam flotation method according to any one of claims 1-8, characterized in that, The preparation method of the amphiphilic Janus nano silica particles includes: grinding hydrophilic nano SiO2 into powder, wetting it with water, and then dispersing it in an organic solvent with a concentration of 20-30 g / L; then adding 0.02-0.05 mol / L of hexadecyltrimethoxysilane and reacting it under the catalysis of triethylamine.

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