Foam gel material as well as preparation method and application thereof

Abstract

The invention provides a foam gel material as well as a preparation method and application thereof, and belongs to the technical field of environmental pollution control. The foam gel material provided by the invention is prepared from the following raw materials in percentage by mass: 0.2 to 0.4 percent of foaming agent, 0.4 to 0.6 percent of polymer foam stabilizer, 0.1 to 1.0 percent of sodium pyrosulfite, 0.01 to 0.02 percent of ferrous sulfate heptahydrate and the balance of water. Sodium pyrosulfite and ferrous sulfate heptahydrate are used as reducing agents and can reduce Cr (VI) into Cr (III), the generated Cr (III) and Fe < 3 + > (Fe < 2 + > oxidation products) are jointly subjected to cross-linking reaction with the polymer foam stabilizer, and a stable gel barrier structure is constructed in situ, so that the synergistic remediation effect of pollution blocking, structure curing and pollutant in-situ reduction is achieved; therefore, the repairing effect is improved.

Description

Technical Field

[0001] This invention belongs to the field of environmental pollution control technology, specifically relating to a foam gel material, its preparation method, and its application. Background Technology

[0002] Hexavalent chromium (Cr(VI)) is a common, highly toxic heavy metal pollutant in groundwater, exhibiting strong mobility and high carcinogenicity. It is widely derived from seepage in wastewater from electroplating, leather processing, metallurgy, and chemical industries. Existing remediation methods, such as pump-suction treatment, single chemical reduction, and solidification / stabilization, generally suffer from drawbacks such as long construction cycles, easy reagent loss, and difficulty in precisely controlling the reaction area. A few studies have used gel materials for groundwater remediation, but these are prone to permeation and struggle to form a uniform coverage in porous media, resulting in poor remediation outcomes.

[0003] Therefore, how to modify gel materials to improve the repair effect has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a foam gel material, its preparation method, and its applications. The foam gel material provided by this invention can achieve a synergistic remediation effect of pollution blocking, structural solidification, and in-situ reduction of pollutants. It also exhibits high stability and strong sealing ability, making it suitable for efficient in-situ remediation of groundwater pollution with medium to high concentrations of heavy metals.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a foam gel material prepared from raw materials comprising the following mass percentages: 0.2-0.4% foaming agent, 0.4-0.6% polymeric foam stabilizer, 0.1-1.0% sodium metabisulfite, 0.01-0.02% ferrous sulfate heptahydrate, and the balance being water.

[0006] Preferably, the foaming agent is an anionic surfactant.

[0007] Preferably, the anionic surfactant includes at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

[0008] Preferably, the polymeric foam stabilizer includes at least one of xanthan gum, sodium alginate, chitosan, and gelatin.

[0009] Preferably, the water is deionized water or Cr(VI) contaminated groundwater.

[0010] Preferably, the foam gel material is prepared from raw materials comprising the following mass percentages: 0.2% foaming agent, 0.5% polymeric foam stabilizer, 0.2-0.5% sodium metabisulfite, 0.01-0.02% ferrous sulfate heptahydrate, and the balance being water.

[0011] The present invention also provides a method for preparing the foam gel material described in the above technical solution, comprising: A foaming agent, a polymeric foam stabilizer, sodium metabisulfite, ferrous sulfate heptahydrate, and water are mixed and then foamed and gelled sequentially to obtain a foam gel material.

[0012] Preferably, the foaming temperature is room temperature and the foaming time is 1-5 minutes.

[0013] The present invention also provides the application of the foam gel material described in the above technical solution or the foam gel material prepared by the preparation method described in the above technical solution in the treatment of hexavalent chromium polluted water.

[0014] Preferably, the concentration of hexavalent chromium in the hexavalent chromium-contaminated water is 1~500 mg / L.

[0015] This invention provides a foam gel material prepared from raw materials comprising the following mass percentages: 0.2-0.4% foaming agent, 0.4-0.6% polymeric foam stabilizer, 0.1-1.0% sodium metabisulfite, 0.01-0.02% ferrous sulfate heptahydrate, and the balance being water. In this invention, sodium metabisulfite and ferrous sulfate heptahydrate act as reducing agents, capable of reducing Cr(VI) to Cr(III). The generated Cr(III) reacts with Fe... 3+ (Fe) 2+ The oxidation products (often referred to as "oxidation products") undergo a cross-linking reaction with the polymer foam stabilizer, constructing a stable gel barrier structure in situ. This achieves a synergistic remediation effect of pollution blocking, structural solidification, and in-situ reduction of pollutants, thereby improving the remediation efficacy. Experimental results show that the medium permeability coefficient decreased from 2.9 × 10⁻⁶ after using the foam gel material provided by this invention. -3 cm / s decreased to 7.8 × 10 -8 Below cm / s, it meets and exceeds the requirements of conventional cutoff walls <1×10 -7 The required speed is cm / s, with a blocking rate of 99.97%. Attached Figure Description

[0016] Figure 1 The gelation time is used in Comparative Examples 1-5; Figure 2 The gelation times are for Comparative Examples 6-10 and Examples 1-10; Figure 3 Here is a physical image of the foam gel material prepared in Comparative Example 2; Figure 4 Here is a photograph of the foam gel material prepared in Example 9; Figure 5 The diagram shows the apparatus used to test the permeability coefficient of the foam gel materials prepared in Examples 11-14. In the figure, 1 is a variable head pipe, 2 is a sand column, 3 is a water tank, 4 is a water source, 5 is an inlet pipe clamp, 6 is an exhaust pipe, 7 is an outlet pipe, 5(1), 5(2) and 5(3) are all stop clamps, and H1 and H2 are the head heights at the beginning and end of the process, respectively. Figure 6 The permeability coefficients of the foam gel materials prepared in Examples 11-14; Figure 7 This refers to the total volume of exudate after the foam was injected in Examples 12 and 14; Figure 8 The percolation blocking rate after foam injection in Examples 12 and 14. Detailed Implementation

[0017] This invention provides a foam gel material prepared from raw materials comprising the following mass percentages: 0.2-0.4% foaming agent, 0.4-0.6% polymeric foam stabilizer, 0.1-1.0% sodium metabisulfite, 0.01-0.02% ferrous sulfate heptahydrate, and the balance being water.

[0018] The present invention does not have any special limitations on the source of the raw materials, and commercially available products known to those skilled in the art can be used.

[0019] The raw materials for preparing the foam gel material provided by the present invention, by weight percentage, include 0.2-0.4% foaming agent; the foaming agent is preferably an anionic surfactant; the anionic surfactant preferably includes at least one of sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS). In the present invention, the foaming agent plays a foaming role.

[0020] In one embodiment, the foaming agent may be 0.2% or 0.3% by mass.

[0021] The raw materials for preparing the foam gel material provided by this invention, by weight percentage, include 0.4-0.6% polymeric foam stabilizer; the polymeric foam stabilizer preferably includes at least one selected from xanthan gum, sodium alginate, chitosan, and gelatin. In this invention, the carboxyl / hydroxyl / amino groups in the polymeric foam stabilizer react with Cr(III) and Fe... 3+ Cross-linking forms a gel network.

[0022] In one embodiment, the polymer foam stabilizer may be 0.4%, 0.5%, or 0.6% by mass.

[0023] The raw materials for preparing the foam gel material provided by this invention include 0.1-1.0% sodium metabisulfite (Na2S2O5) by mass percentage. As one embodiment, the mass percentage of sodium metabisulfite can be 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, or 0.9%. In this invention, the sodium metabisulfite can synergistically reduce Cr(VI) to Cr(III) with ferrous sulfate heptahydrate, thereby better reducing Cr(VI) to Cr(III).

[0024] The raw materials for preparing the foam gel material provided by the present invention include 0.01-0.02% ferrous sulfate heptahydrate (FeSO4·7H2O) by mass percentage. In the present invention, the ferrous sulfate heptahydrate can synergistically reduce Cr(VI) to Cr(III) with sodium metabisulfite.

[0025] The raw materials for preparing the foam gel material provided by this invention, by weight percentage, include the remainder water; the water is deionized water or Cr(VI) contaminated groundwater. In this invention, the water is used as a solvent.

[0026] The foam gel material provided by this invention is suitable for groundwater environments with hexavalent chromium concentrations of 1-500 mg / L. By injecting this material, preliminary sealing of contaminated channels can be achieved. The reducing agents sodium metabisulfite and ferrous sulfate heptahydrate loaded in this material can reduce Cr(VI) to Cr(III), and the generated Cr(III) reacts with Fe... 3+ (Fe) 2+ The oxidation products react with the polymer foam stabilizer to form a cross-linking reaction, thereby constructing a stable gel barrier structure in situ. This achieves a synergistic remediation effect of pollution blocking, structural solidification, and in-situ reduction of pollutants, thus improving the remediation effect.

[0027] The foam gel material provided by this invention can achieve integrated blocking and repair: by injecting foam, it simultaneously blocks the channels of polluted water flow and reduces Cr(VI) in situ, avoiding the complex process of step-by-step treatment; it constructs a stable barrier in situ: the Cr(VI) reduction product Cr(III) and Fe 2+ Oxidation product Fe 3+ It can crosslink with polymers (such as xanthan gum, sodium alginate, etc.) to form a gel network, achieving a dual effect of blocking and solidification; rapid osmosis reduction: the permeability coefficient is reduced from 2.9×10 -3 cm / s decreased to 7.8 × 10 -8 For solutions with a permeability below cm / s, the permeability coefficient is reduced to 5.5 × 10⁻⁶ for solutions containing 0.02 wt% FeSO₄·7H₂O. -8cm / s; Significantly blocked water outflow: Within 12 hours of constant head test, the volume of foam seepage without injection was 32L; the foam seepage volume of Cr(VI) contaminated groundwater was only 10mL, and the foam seepage volume of deionized water was 298mL, with blocking rates of 99.97% and 99.07%, respectively.

[0028] This invention utilizes foam as a carrier to uniformly disperse sodium metabisulfite in a stable foam system. After being injected into the contaminated area, it generates Cr through a reduction reaction. 3+ It crosslinks with polymer foam stabilizers to form a gel barrier, achieving long-term stable pollution control and in-situ remediation.

[0029] The present invention also provides a method for preparing the foam gel material described in the above technical solution, comprising: A foaming agent, a polymeric foam stabilizer, sodium metabisulfite, ferrous sulfate heptahydrate, and water are mixed and then foamed and gelled sequentially to obtain a foam gel material.

[0030] In this invention, the mixing of the foaming agent, polymeric foam stabilizer, sodium metabisulfite, ferrous sulfate heptahydrate and water is preferably carried out by mixing water and polymeric foam stabilizer, and then adding the foaming agent, sodium metabisulfite and ferrous sulfate heptahydrate in sequence.

[0031] In this invention, the mixing of water and polymeric foam stabilizer is preferably carried out under stirring conditions; the stirring speed is preferably 300-500 rpm; and the stirring time is preferably 5-10 min. By limiting the stirring process parameters within the above range, this invention ensures that the polymeric foam stabilizer is completely dispersed in the water.

[0032] As one implementation, the stirring speed can be 350 rpm, 400 rpm, or 450 rpm; the stirring time can be 6 min, 7 min, 8 min, or 9 min.

[0033] In this invention, the polymeric foam stabilizer is preferably added to water slowly. This invention does not impose any particular limitation on the slow addition operation; any operation well-known to those skilled in the art can be used. By adding the polymer slowly to the water, this invention avoids pouring it all at once and prevents the formation of clumps.

[0034] The present invention does not have any special limitations on the operation of sequentially adding foaming agent, sodium metabisulfite and ferrous sulfate heptahydrate, and any technical solution for preparing the mixture well known to those skilled in the art can be used.

[0035] In this invention, the foaming temperature is preferably room temperature; the foaming time is preferably 1 to 5 minutes. As one embodiment, the foaming time can be 2 minutes, 3 minutes, or 4 minutes.

[0036] In this invention, the foaming is preferably carried out in a mechanical foaming machine; the rotation speed of the mechanical foaming machine is preferably 4000~5000 rpm. As one embodiment, the rotation speed of the mechanical foaming machine can be 4100 rpm, 4200 rpm, 4300 rpm, 4400 rpm, 4500 rpm, 4600 rpm, 4700 rpm, 4800 rpm, or 4900 rpm. This invention does not impose a specific limitation on the model of the mechanical foaming machine; any instrument or equipment well known to those skilled in the art can be used.

[0037] In this invention, the physical properties of the foamed material are as follows: foam mass 2~3; average bubble diameter 20~150μm; foam half-life: ≥50h (under static conditions).

[0038] In this invention, the temperature of the gel is preferably room temperature; the gelation time is preferably 1 to 3 hours.

[0039] The preparation method provided by this invention is simple.

[0040] The present invention also provides the application of the foam gel material described in the above technical solution or the foam gel material prepared by the preparation method described in the above technical solution in the treatment of hexavalent chromium polluted water.

[0041] In this invention, the concentration of hexavalent chromium in the hexavalent chromium-polluted water is preferably 1~500 mg / L.

[0042] In this invention, the foam gel material is preferably injected into the area where hexavalent chromium pollution is treated after foaming, and then gelled.

[0043] The present invention does not impose any special limitations on the injection operation; any operation known to those skilled in the art can be used.

[0044] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0045] The instruments and materials used in the examples and comparative examples are shown in Tables 1 and 2.

[0046] Table 1 Main Instruments

[0047] Table 2 Main Materials

[0048] Comparative Example 1 A foam gel material is prepared from the following raw materials in the indicated mass percentages: 0.2% foaming agent SDS, 0.5% xanthan gum, 0.01% ferrous sulfate heptahydrate, and the balance being 0.5 g / L Cr(VI) contaminated groundwater; The preparation method of the foam gel material is as follows: Add Cr(VI) contaminated groundwater to the reaction vessel and start stirring (400 rpm) to form a stable vortex; slowly sprinkle xanthan gum while stirring and continue stirring for 5 minutes, then add SDS and stir evenly, then slowly add ferrous sulfate heptahydrate to form a uniform foaming liquid. Use a Wu Yin mixer (4500 rpm) to stir for 2 minutes to obtain foam; Pour the foam into a 250mL beaker and start timing from the beginning of pouring. Then, every 10 minutes, invert the beaker 180° and hold it for 30 seconds. If there is no flow or collapse, the gel is considered "completed" and recorded as the gelation time T. gel (min), gelation time as follows Figure 1 As shown.

[0049] Comparative Example 2 Based on Comparative Example 1, the content of ferrous sulfate heptahydrate was changed to 0.02%, and the Cr(VI) contaminated groundwater was replenished to 100%, with other conditions remaining unchanged. The gelation time was as follows. Figure 1 As shown.

[0050] Comparative Example 3 Based on Comparative Example 1, the content of ferrous sulfate heptahydrate was changed to 0.03%, and the Cr(VI) contaminated groundwater was replenished to 100%, with other conditions remaining unchanged. The gelation time was as follows. Figure 1 As shown.

[0051] Comparative Example 4 Based on Comparative Example 1, the content of ferrous sulfate heptahydrate was changed to 0.04%, and the Cr(VI) contaminated groundwater was replenished to 100%, with other conditions remaining unchanged. The gelation time was as follows. Figure 1 As shown.

[0052] Comparative Example 5 Based on Comparative Example 1, the content of ferrous sulfate heptahydrate was changed to 0.05%, and the Cr(VI) contaminated groundwater was replenished to 100%, with other conditions remaining unchanged. The gelation time was as follows. Figure 1 As shown.

[0053] from Figure 1 It can be seen that the gelation time of comparative examples 1 to 5 is less than 300 min.

[0054] Example 1 A foam gel material is prepared from the following raw materials in the indicated mass percentages: 0.2% foaming agent SDS, 0.5% xanthan gum, 0.1% sodium metabisulfite, 0.01% ferrous sulfate heptahydrate, and the balance being 0.5 g / L Cr(VI) contaminated groundwater; The preparation method of the foam gel material is as follows: Cr(VI) contaminated groundwater was added to the reaction vessel and stirring was started (400 rpm) to form a stable vortex. Xanthan gum was slowly sprinkled in while stirring, and stirring was continued for 5 minutes. Then SDS was added and stirred evenly. Sodium metabisulfite and ferrous sulfate heptahydrate were then slowly added to form a uniform foaming solution. Use a Wu Yin mixer (4500 rpm) to stir for 2 minutes to obtain foam; Pour the foam into a 250mL beaker and start timing from the beginning of pouring. Then, every 10 minutes, invert the beaker 180° and hold it for 30 seconds. If there is no flow or collapse, the gel is considered "completed" and recorded as the gelation time T. gel (min), gelation time as follows Figure 2 As shown.

[0055] Example 2 Based on Example 1, the sodium metabisulfite content was changed to 0.2%, and the Cr(VI) contaminated groundwater was replenished to 100%, while other conditions remained unchanged. The gelation time was as follows. Figure 2 As shown.

[0056] Example 3 Based on Example 1, the sodium metabisulfite content was changed to 0.3%, and the Cr(VI) contaminated groundwater was replenished to 100%, while other conditions remained unchanged. The gelation time was as follows. Figure 2 As shown.

[0057] Example 4 Based on Example 1, the sodium metabisulfite content was changed to 0.4%, and the Cr(VI) contaminated groundwater was replenished to 100%, while other conditions remained unchanged. The gelation time was as follows. Figure 2 As shown.

[0058] Example 5 Based on Example 1, the sodium metabisulfite content was changed to 0.5%, and the Cr(VI) contaminated groundwater was replenished to 100%, while other conditions remained unchanged. The gelation time was as follows. Figure 2 As shown.

[0059] Example 6 Based on Example 1, the content of ferrous sulfate heptahydrate was changed to 0.02%, and the Cr(VI) contaminated groundwater was replenished to 100%, while other conditions remained unchanged. The gelation time was as follows. Figure 2 As shown.

[0060] Example 7 Based on Example 6, the sodium metabisulfite content was changed to 0.2%, and the Cr(VI) contaminated groundwater was replenished to 100%, while other conditions remained unchanged. The gelation time was as follows. Figure 2 As shown.

[0061] Example 8 Based on Example 6, the sodium metabisulfite content was changed to 0.3%, and the Cr(VI) contaminated groundwater was replenished to 100%, while other conditions remained unchanged. The gelation time was as follows. Figure 2 As shown.

[0062] Example 9 Based on Example 6, the sodium metabisulfite content was changed to 0.4%, and the Cr(VI) contaminated groundwater was replenished to 100%, while other conditions remained unchanged. The gelation time was as follows. Figure 2 As shown.

[0063] Example 10 Based on Example 6, the sodium metabisulfite content was changed to 0.5%, and the Cr(VI) contaminated groundwater was replenished to 100%, while other conditions remained unchanged. The gelation time was as follows. Figure 2 As shown.

[0064] Comparative Example 6 Based on Example 1, ferrous sulfate heptahydrate was omitted, and Cr(VI) contaminated groundwater was replenished to 100%, while other conditions remained unchanged. The gelation time was as follows. Figure 2 As shown.

[0065] Comparative Example 7 Based on Comparative Example 6, the sodium metabisulfite content was changed to 0.2%, and the Cr(VI) contaminated groundwater was replenished to 100%, with other conditions remaining unchanged. The gelation time was as follows. Figure 2 As shown.

[0066] Comparative Example 8 Based on Comparative Example 6, the sodium metabisulfite content was changed to 0.3%, and the Cr(VI) contaminated groundwater was replenished to 100%, with other conditions remaining unchanged. The gelation time was as follows. Figure 2 As shown.

[0067] Comparative Example 9 Based on Comparative Example 6, the sodium metabisulfite content was changed to 0.4%, and the Cr(VI) contaminated groundwater was replenished to 100%, with other conditions remaining unchanged. The gelation time was as follows. Figure 2 As shown.

[0068] Comparative Example 10 Based on Comparative Example 6, the sodium metabisulfite content was changed to 0.5%, and the Cr(VI) contaminated groundwater was replenished to 100%, with other conditions remaining unchanged. The gelation time was as follows. Figure 2 As shown.

[0069] from Figure 2 It can be seen that adding ferrous sulfate heptahydrate can shorten the gelation time.

[0070] The physical image of the foam gel material prepared in Comparative Example 2 is shown below. Figure 3 As shown; a physical image of the foam gel material prepared in Example 9 is shown. Figure 4 As shown.

[0071] from Figure 3 and 4 The comparison shows that adding sodium metabisulfite can reduce the porosity of the material, thereby constructing a stable gel barrier structure in situ.

[0072] Example 11 (0.01% FeSO4·7H2O + 0.4% Na2S2O5 + 0.5% Cr(VI)) A foam gel material is prepared from the following raw materials in the indicated mass percentages: foaming agent SDS 0.2%, xanthan gum 0.5%, sodium metabisulfite 0.4%, ferrous sulfate heptahydrate 0.01%, and the balance being 0.5 g / L Cr(VI) contaminated groundwater; The preparation method of the foam gel material is as follows: Cr(VI) contaminated groundwater was added to the reaction vessel and stirring was started (400 rpm) to form a stable vortex. Xanthan gum was slowly sprinkled in while stirring, and stirring was continued for 5 minutes. Then SDS was added and stirred evenly. Sodium metabisulfite and ferrous sulfate heptahydrate were then slowly added to form a uniform foaming solution. Using a Wu Yin mixer, stir at 4500 rpm for 2 minutes to obtain foam; Variable head device: measuring pipe / riseer (inner diameter 0.6mm), connecting hose and three-way valve; Place 40-mesh mesh at both ends of the sand column, weigh 128g of 40-70 mesh quartz sand, fill it into the sand column with an inner diameter of 4cm and a length of 10cm, lightly tamp it every 2cm, scrape the end face flat, apply a thin layer of Vaseline to the joint and end face, install the end cap, and tighten the clamp. Open the lower inlet and inject a 500 mg / L hexavalent chromium solution at a low flow rate. When the upper end continuously and stably outputs water without bubbles, close the inlet and wipe the outer wall dry. Use a peristaltic pump to inject foam from the lower end at a rate of 10 mL / min. Stop injecting when foam continuously overflows from the upper end. Let it stand for 3 hours to gel and obtain the foam gel material.

[0073] Comparative Example 11 Based on Example 11, sodium metabisulfite and ferrous sulfate heptahydrate were replaced with nano-zero valent iron, while other conditions remained unchanged.

[0074] Comparative Example 12 Based on Example 11, sodium metabisulfite and ferrous sulfate heptahydrate were replaced with ascorbic acid, while other conditions remained unchanged.

[0075] Comparative Example 13 Based on Example 11, sodium metabisulfite and ferrous sulfate heptahydrate were replaced with citric acid, while other conditions remained unchanged.

[0076] Comparative Example 14 Based on Example 11, sodium metabisulfite and ferrous sulfate heptahydrate were replaced with oxalic acid, while other conditions remained unchanged.

[0077] In Comparative Examples 11-14, the addition of the reducing agent described above prevented the formation of gels, thus making it impossible to determine the corresponding permeability coefficient and blocking rate.

[0078] Example 12 (0.02% FeSO4·7H2O + 0.4% Na2S2O5 + 0.5% Cr(VI)) Based on Example 11, the content of ferrous sulfate heptahydrate was set to 0.02%, and the Cr(VI) contaminated groundwater was replenished to 100%, while other conditions remained unchanged.

[0079] Example 13 (0.01% FeSO4·7H2O + 0.4% Na2S2O5) Based on Example 11, the 0.5 g / L Cr(VI) contaminated groundwater was replaced with deionized water, while other conditions remained unchanged.

[0080] Example 14 (0.02% FeSO4·7H2O + 0.4% Na2S2O5) Based on Example 12, the 0.5 g / L Cr(VI) contaminated groundwater was replaced with deionized water, while other conditions remained unchanged.

[0081] The permeability coefficient of the foam gel materials prepared in Examples 11-14 was tested. The test method was as follows: after filling the water head pipe with water to the required height, the water stop clamp 5 (2) was closed, and the initial water head height and initial time in the variable water head pipe were recorded. The changes in water head and time were recorded at predetermined time intervals. After recording these measurements 2 to 3 times, the water level in the water head pipe was raised back to the required height, and the measurements were recorded several times. The test was repeated 5 to 6 times or more. The permeability coefficient was calculated using the following formula: K= lg ; In the formula, K is the permeability coefficient, cm / s; a is the cross-sectional area, in cm². 2 L is the length of the sand column, in cm; A is the cross-sectional area of ​​the soil sample / sand column, in cm². 2 t is the time interval during which the water head drops from H1 to H2, in seconds; H1 and H2 are the water head heights at the start and end times, respectively, in centimeters.

[0082] The apparatus diagrams for testing the permeability coefficient of the foam gel materials prepared in Examples 11-14 are shown below. Figure 5 As shown in the figure, 1 is a variable head pipe, 2 is a sand column, 3 is a water tank, 4 is a water supply pipe, 5 is an inlet pipe clamp, 6 is an exhaust pipe, 7 is an outlet pipe, 5(1), 5(2) and 5(3) are all stop clamps, and H1 and H2 are the head heights at the beginning and end times, respectively.

[0083] The permeability coefficients of the foam gel materials prepared in Examples 11-14 are as follows: Figure 6 As shown.

[0084] from Figure 6 It can be seen that the medium permeability coefficient of the foam gel materials prepared using Examples 11-12 all increased from 2.9 × 10⁻⁶. -3 cm / s decreased to 7.8 × 10 -8 Below cm / s, it meets and exceeds the requirements of conventional cutoff walls <1×10 -7 The required permeability coefficient is cm / s; among them, the technical solution of adding 0.02% ferrous sulfate heptahydrate reduces the permeability coefficient to 5.5×10⁻⁶. -8 cm / s; the medium permeability coefficient of the foam gel materials prepared using Examples 13-14 decreased to 3.1 × 10⁻⁶ after 3 hours. -5 cm / s, which decreased to 5.2 × 10 cm / s after 24 hours. -7 cm / s and 7.2×10 -8 cm / s.

[0085] Under a constant head difference Δh = 1.5 m, seepage was started and timing was initiated. Leachate was collected and its volume was recorded. The cumulative outflow volume of the sand column before and after foam treatment was compared with the Cr(VI) concentration of the leachate, and the blocking rate and reduction inhibition effect were calculated.

[0086] The formula for calculating the blocking rate is as follows: ; In the formula, V foam For a sand column injected with foam, the volume of leachate after 12 hours; V blank The volume of leachate after 12 hours is for a sand column without foam injection.

[0087] The total volume of exudate after injecting the foam in Examples 12 and 14 is as follows: Figure 7 As shown.

[0088] The percolation blocking rate after foaming in Examples 12 and 14 is as follows: Figure 8 As shown.

[0089] from Figures 7-8 It can be seen that the permeation solution volume of the sand column without foam injection after 12 hours is 32L. After 12 hours of foam injection in Example 12 and foam injection in Example 14, the permeation volume is reduced to 10mL and 298mL respectively, and the blocking rates are 99.97% and 99.07% respectively.

[0090] The foam gel material provided by this invention can achieve a synergistic remediation effect of pollution blocking, structural solidification and in-situ reduction of pollutants, and has high stability and strong sealing ability, making it suitable for efficient in-situ treatment of groundwater pollution with medium and high concentrations of heavy metals.

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A foam gel material, prepared from raw materials comprising the following mass percentages: 0.2-0.4% foaming agent, 0.4-0.6% polymeric foam stabilizer, 0.1-1.0% sodium metabisulfite, 0.01-0.02% ferrous sulfate heptahydrate, and the balance being water.

2. The foam gel material according to claim 1, characterized in that, The foaming agent is an anionic surfactant.

3. The foam gel material according to claim 2, characterized in that, The anionic surfactant includes at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

4. The foam gel material according to claim 1, characterized in that, The polymeric foam stabilizer includes at least one of xanthan gum, sodium alginate, chitosan, and gelatin.

5. The foam gel material according to claim 1, characterized in that, The water is either deionized water or Cr(VI) contaminated groundwater.

6. The foam gel material according to claim 1, characterized in that, The foam gel material is prepared from raw materials comprising the following mass percentages: 0.2% foaming agent, 0.5% polymeric foam stabilizer, 0.2-0.5% sodium metabisulfite, 0.01-0.02% ferrous sulfate heptahydrate, and the balance being water.

7. A method for preparing the foam gel material according to any one of claims 1 to 6, comprising: A foaming agent, a polymeric foam stabilizer, sodium metabisulfite, ferrous sulfate heptahydrate, and water are mixed and then foamed and gelled sequentially to obtain a foam gel material.

8. The preparation method according to claim 7, characterized in that, The foaming temperature is room temperature, and the foaming time is 1~5 minutes.

9. The application of the foam gel material according to any one of claims 1 to 6 or the foam gel material prepared by the preparation method according to claim 7 or 8 in the treatment of hexavalent chromium polluted water.

10. The application according to claim 9, characterized in that, The concentration of hexavalent chromium in the polluted water is 1~500 mg / L.

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