Method for adsorbing CL-20 by using silicic acid and sodium silicate and application thereof

Abstract

The invention discloses a method for adsorbing CL-20 by utilizing silicic acid and sodium silicate and application of the method, and belongs to the technical field of environmental remediation, the method for adsorbing CL-20 by utilizing silicic acid and sodium silicate comprises the following steps: adding an adsorbent with a set dosage into a high-concentration strong acid waste liquid containing CL-20; the adsorbent is silicic acid, sodium silicate or a mixture of the silicic acid and the sodium silicate; stirring the obtained high-concentration strong acid waste liquid under set conditions; and detecting the stirred solution, and detecting the change of the concentration of CL-20 in the adsorption process to finish adsorption. The invention provides a simple, efficient and economical CL-20 removal method, which can be applied to the fields of environmental remediation and water treatment, such as treatment of explosive production wastewater, contaminated soil leacheate and the like, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of environmental remediation, and in particular to a method for absorbing CL-20 in high-concentration strong acid waste liquid by using silicic acid and sodium silicate and application thereof. Background Art

[0003] Among the numerous industrial wastewater pollutants, hexanitrohexaazaisowurtzitane (chemical formula C6H6N 12 O 12 , abbreviated as HNIW, commonly known as CL-20), is an emerging high-energy explosive. Its unique and complex molecular structure gives it excellent explosive performance and thermal stability, making it one of the most promising energetic materials in the 21st century. CL-20 is widely used in both military and civilian fields, especially in blasting, mining and special materials. However, with the widespread production and use of CL-20, the high-concentration strong acid wastewater containing CL-20 produced by it has also become an environmental hazard. The CL-20 molecule has extremely strong resistance to degradation, and traditional microbial degradation methods are ineffective against it, which makes the treatment and removal of CL-20 a major problem. At present, there are limited methods for treating wastewater containing CL-20, and related research is still in its infancy. Therefore, exploring an economical, efficient and environmentally friendly CL-20 removal method has become an urgent task.

[0004] In summary, as an emerging high-energy material, the strong acid wastewater produced by CL-20 has become an environmental problem that needs to be solved urgently. At present, there are relatively few studies on the treatment of CL-20 wastewater, especially the treatment method of high-concentration strong acid wastewater needs to be developed urgently. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a method for utilizing the unique adsorption characteristics of silicic acid and sodium silicate on CL-20, and realizing efficient removal of CL-20 in high-concentration strong acid waste liquid by precisely controlling the reaction conditions and the amount of adsorbent.

[0006] The present invention adopts the following technical solution.

[0007] The first aspect of the present invention discloses a method for adsorbing CL-20 using silicic acid and sodium silicate, comprising the following steps:

[0008] Adding a set dosage of adsorbent into the high-concentration strong acid waste liquid containing CL-20;

[0009] The adsorbent is silicic acid, sodium silicate or a mixture of the two;

[0010] Under set conditions, the waste liquid after the adsorbent is added is stirred;

[0011] The stirred solution was tested to measure the change in CL-20 concentration during the adsorption process, and the adsorption was completed.

[0012] Preferably, the silicic acid and sodium silicate need to be placed in an oven and dried at 105° C. for 2 hours before being added.

[0013] Preferably, the mass ratio of the mixture of silicic acid and sodium silicate is 1:(1-1.5).

[0014] Preferably, the set dosage of the adsorbent is 0.8-1.2 g / L.

[0015] Preferably, the set condition is stirring at 200 rpm at 25° C. for 12 hours.

[0016] Preferably, the stirred solution is separated by a 0.22 μm filter membrane, and the concentration of CL-20 in the supernatant is determined by high performance liquid chromatography to calculate the removal rate.

[0017] Preferably, the adsorption process is a non-spontaneous process with exothermic and entropy-reducing properties.

[0018] Preferably, the adsorption process is controlled by chemical adsorption.

[0019] Preferably, the CL-20 forms multilayer adsorption on the surfaces of both silicic acid and sodium silicate.

[0020] A method for adsorbing CL-20 by using silicic acid and sodium silicate is applied in high-concentration strong acid industrial wastewater containing CL-20.

[0021] Compared with the prior art, the beneficial effects of the present invention include at least:

[0022] The present invention utilizes the unique adsorption characteristics of silicic acid and sodium silicate for CL-20, and achieves efficient removal of CL-20 in high-concentration strong acid waste liquid by accurately controlling the reaction conditions and the amount of adsorbent. The method has the advantages of being green, environmentally friendly, and low-cost, and provides a new strategy for environmental remediation and water treatment. The specific implementation steps of the method of the present invention include material preparation, adding the dosage to the CL-20-containing waste liquid and the reaction conditions, monitoring the change of CL-20 concentration, examining different solution concentrations, thermodynamic analysis, studying the maximum adsorption amount, exploring practical applications, expanding the scope of application, and optimizing process parameters. Through the above steps, the present invention provides an environmental remediation and water treatment technology with great potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The morphology of the solid adsorbent before and after the adsorption of CL-20 in Example 1, wherein (a) is before adsorption and (b) is after adsorption;

[0024] Figure 2 The morphology of the solid adsorbent before and after the adsorption of CL-20 in Example 2, wherein (a) is before adsorption and (b) is after adsorption;

[0025] Figure 3 The effects of different parameters in Example 1 and Example 2, where (a) is different dosages; (b) is the temperature effect; (c) is the contact time; and (d) is the dilution multiple. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0027] Silicic acid (H2SiO3) is an inorganic compound formed by the hydrolysis of silicon dioxide (SiO2) in water. It is a cheap and readily available material that is widely present in nature. Silicic acid has unique surface chemical properties and porous structures, which enable it to exhibit excellent adsorption performance for various pollutants. In recent years, with the increasing popularity of green environmental protection concepts, silicic acid has played an increasingly important role in the field of wastewater treatment. H2SiO3 can adsorb or chemically react with a variety of pollutants such as heavy metal ions and organic pollutants, effectively removing pollutants. Therefore, it is very necessary to develop a method that utilizes the unique properties of H2SiO3 while overcoming existing limitations.

[0028] Sodium silicate (Na2SiO3), also known as water glass, is a common chemical made by melting silicon dioxide and sodium hydroxide at high temperature. It has good solubility and low price, and is widely used in building materials, rubber, food additives and other industries. Na2SiO3 also shows good application prospects in the field of wastewater treatment. In addition, Na2SiO3 has good reactivity with a variety of organic pollutants (such as dyes, pesticides, etc.), making it a potential material in the field of wastewater treatment.

[0029] Therefore, the inventors of the present application realized that silicic acid (H2SiO3) has excellent adsorption performance and porous structure, making it suitable as an adsorbent to treat CL-20 pollution, and sodium silicate (Na2SiO3) can be used as a precursor to generate H2SiO3 under acidic conditions, providing a potential strategy for the removal of CL-20. Therefore, the present invention aims to explore the adsorption performance of Na2SiO3 and H2SiO3 on CL-20, reveal the adsorption mechanism by systematically studying the key factors affecting the adsorption behavior, and further explore the application potential of this method in the field of environmental remediation and water treatment, in order to provide a green and efficient solution for the treatment of high-concentration strong acid wastewater.

[0030] The present invention provides a specific implementation method of removing CL-20 from high-concentration strong acid waste liquid by using silicic acid and sodium silicate. The specific steps are as follows:

[0031] Step 1, adding a set dosage of adsorbent to high-concentration strong acid waste liquid containing CL-20;

[0032] The adsorbent is any one of silicic acid (H2SiO3), sodium silicate (Na2SiO3), and a mixture thereof.

[0033] In a preferred but non-limiting embodiment of the present invention, the silicic acid (H2SiO3) and sodium silicate (Na2SiO3) need to be placed in an oven and dried at 105°C for 2 hours;

[0034] The mass ratio of the mixture of silicic acid (H2SiO3) and sodium silicate (Na2SiO3) is 1:(1-1.5);

[0035] Further preferably, the adsorption amount is highest when the mass ratio of the mixture of the two is 1:1;

[0036] Regardless of whether the adsorbent is silicic acid (H2SiO3), sodium silicate (Na2SiO3), or a mixture of the two, the set dosage is 0.8-1.2 g / L. More preferably, the adsorption amount is the highest when the dosage is 1 g / L.

[0037] It is worth noting that the sodium silicate (Na2SiO3) is hydrolyzed to generate silicic acid (H2SiO3) under acidic conditions.

[0038] Step 2, stirring the high-concentration strong acid waste liquid obtained in step 1 under set conditions;

[0039] In a preferred but non-limiting embodiment of the present invention, the set condition is stirring at 200 rpm at 25° C. for 12 hours.

[0040] Step 3, testing the stirred solution obtained in step 2, measuring the change in CL-20 concentration during the adsorption process, and completing the adsorption.

[0041] The detection is specifically to separate the stirred solution through a 0.22 μm filter membrane, determine the concentration of CL-20 in the supernatant by high performance liquid chromatography, and calculate the removal rate. The concentration of CL-20 in the high-concentration strong acid waste liquid of the original CL-20 has been measured or prepared before step 1.

[0042] Example 1: Adsorption of CL-20 by silicic acid (H2SiO3)

[0043] Step 1: Material Preparation

[0044] According to the experimental requirements, a certain amount of silicic acid (H2SiO3) was weighed, placed in an oven, and dried at 105°C for 2 hours. This step provided the required reagents for the subsequent adsorption experiment. After the adsorption was completed, electron microscopy was performed, and the results are shown in Figure 1 (a,b).

[0045] Step 2: Dosage Optimization

[0046] Weigh 0.1, 0.4, 0.7, 1.0, 1.4, 1.7 and 2.0 g of H2SiO3 powder and add them to 100 mL of CL-20 simulated waste liquid. Stir at 200 rpm for 12 hours at 25°C, then filter through a 0.22 μm filter membrane. Use high performance liquid chromatography to determine the concentration of CL-20 in the supernatant and calculate the removal rate. The experimental results are shown in Figure 3 (a) shows that when the dosage is 0.1 g, the adsorption capacity of H2SiO3 on CL-20 is the highest, which is 75.42 mg / g, and the removal rate is 65.13%.

[0047] Step 3: Temperature Effect Study

[0048] Repeat the experiment in step 2 at 25℃, 35℃ and 45℃, and the dosage is fixed at 1g. The experimental results are shown in Figure 3 (b) The results show that as the temperature increases, the equilibrium adsorption capacity of H2SiO3 on CL-20 shows a downward trend, from 8.96 mg / g at 25°C to 5.28 mg / g at 45°C, and the removal rate drops from 77.36% to 45.59%.

[0049] Step 4: Kinetic studies

[0050] At 25°C, 0.1 g H2SiO3 was added to 100 mL of CL-20 simulated waste liquid, and samples were taken at different time points (2, 5, 10, 20, 30, 60, 120, 240, 360, 480, 600 and 720 minutes) to determine the CL-20 concentration. The experimental results are shown in Figure 3 (c) The results show that the adsorption process conforms to the pseudo-second-order kinetic model (R 2 =0.998), indicating that the adsorption is mainly controlled by chemical adsorption.

[0051] Step 5: Concentration Effect Study

[0052] The original CL-20 waste liquid was diluted 10, 20, 32, 40, 50 and 60 times respectively, and the experiment in step 2 was repeated, with the dosage fixed at 0.1g and the temperature at 25℃. The experimental results are shown in Figure 3 (d) The results show that with the increase of concentration, the equilibrium adsorption capacity of H2SiO3 on CL-20 increased from 13.93 mg / g to 72.35 mg / g, and the removal rate decreased from 86.28% to 62.48%.

[0053] Step 6: Adsorption isotherm study

[0054] At 25°C, adsorption experiments were performed using CL-20 solutions of different concentrations (10-60 times dilution). The results showed that the adsorption of H2SiO3 on CL-20 was more consistent with the Freundlich isotherm model (R 2 =0.995), and the maximum adsorption amount was 87.211 mg / g, indicating that CL-20 formed multilayer adsorption on the surface of silicic acid (H2SiO3).

[0055] Example 2: Adsorption of CL-20 by sodium silicate (Na2SiO3)

[0056] Step 1: Material Preparation

[0057] According to the experimental requirements, a certain amount of sodium silicate (Na2SiO3) was weighed, placed in an oven, and dried at 105°C for 2 hours. This step provided the required reagents for the subsequent adsorption experiment. After the adsorption was completed, electron microscopy was performed, and the results are shown in Figure 2 (a,b).

[0058] Step 2: Dosage Optimization

[0059] Weigh 0.1, 0.4, 0.7, 1.0, 1.4, 1.7 and 2.0 g of Na2SiO3 powder and add them to 100 mL of CL-20 simulated waste liquid. Stir at 200 rpm for 12 hours at 25°C, then filter through a 0.22 μm filter membrane. Use HPLC to determine the concentration of CL-20 in the supernatant and calculate the removal rate. The experimental results are shown in Figure 3 (a), the results show that when the dosage is equivalent to 0.1g solid Na2SiO3, the adsorption amount of CL-20 is the highest, which is 63.37mg / g, and the removal rate is 54.72%.

[0060] Step 3: Temperature Effect Study

[0061] Repeat the experiment in step 2 at 25℃, 35℃ and 45℃, and fix the dosage to 1g Na2SiO3. Figure 3 (b), the results show that as the temperature increases, the equilibrium adsorption capacity of Na2SiO3 on CL-20 shows a downward trend, from 8.34 mg / g at 25℃ to 4.36 mg / g at 45℃, and the removal rate drops from 72.04% to 37.62%.

[0062] Step 4: Kinetic studies

[0063] At 25°C, 0.1 g of Na2SiO3 solution was added to 100 mL of CL-20 simulated waste liquid, and samples were taken at different time points (2, 5, 10, 20, 30, 60, 120, 240, 360, 480, 600 and 720 minutes) to determine the CL-20 concentration. The experimental results are shown in Figure 3 (c) The results show that the adsorption process conforms to the pseudo-second-order kinetic model (R 2 =0.992), indicating that the adsorption is mainly controlled by chemical adsorption.

[0064] Step 5: Concentration Effect Study

[0065] The original CL-20 waste liquid was diluted 10, 20, 32, 40, 50 and 60 times respectively, and the experiment in step 2 was repeated. The dosage was fixed at 0.1g Na2SiO3 solution and the temperature was 25℃. The experimental results are shown in Figure 3 (d) The results show that with the increase of concentration, the equilibrium adsorption capacity of Na2SiO3 on CL-20 increased from 15.99 mg / g to 59.24 mg / g, and the removal rate decreased from 82.89% to 51.16%.

[0066] Step 6: Adsorption isotherm study

[0067] At 25°C, adsorption experiments were performed using CL-20 solutions of different concentrations (10-60 times dilution). The results showed that the adsorption of Na2SiO3 on CL-20 was more consistent with the Freundlich isotherm model (R 2 =0.998), and the maximum adsorption amount was 69.968 mg / g, indicating that CL-20 formed multilayer adsorption on the surface of sodium silicate (Na2SiO3).

[0068] Example 3: Thermodynamic Analysis

[0069] Step 1: Temperature gradient experiment

[0070] 0.1 g H2SiO3 or 0.1 g Na2SiO3 was added to 100 mL CL-20 simulated waste solution (diluted 10 times) at 25°C, 35°C and 45°C, respectively. The mixture was stirred at 200 rpm for 12 hours, and after reaching adsorption equilibrium, the equilibrium concentration of CL-20 in the solution was measured.

[0071] Step 2: Calculation of thermodynamic parameters

[0072] According to the Van't Hoff equation, plot lnK d For the 1 / T curve, the slope and intercept are obtained by linear fitting. The thermodynamic parameters are calculated using the following formula:

[0073] ΔG 0 =-RTlnK d =ΔH 0 -TΔS 0

[0074]

[0075] Where R is the gas constant (8.314 J / mol·K), T is the absolute temperature (K), K d is the distribution coefficient, Ce (mg / L) is the equilibrium concentration, qe (mg / g) is the adsorption amount, adsorption enthalpy ΔH° (KJ / mol), adsorption entropy ΔS° (J / (mol·K)), and Gibbs free energy ΔG° (KJ / mol).

[0076] Step 3: Result Analysis

[0077] The calculation results show:

[0078]

[0079] The values ​​of ΔG° are all positive, indicating that the adsorption process is non-spontaneous; the values ​​of ΔH° are negative, indicating that the adsorption process is an exothermic reaction; the values ​​of ΔS° are negative, indicating the entropy reduction of the adsorption process. These results show that the adsorption process of H2SiO3 and Na2SiO3 on CL-20 is a non-spontaneous process of exothermic and entropy reduction, and the adsorption difficulty increases with the increase of temperature.

[0080] Compared with the prior art, the beneficial effects of the present invention include at least:

[0081] The present invention utilizes the unique adsorption characteristics of silicic acid and sodium silicate for CL-20, and achieves efficient removal of CL-20 in high-concentration strong acid waste liquid by accurately controlling the reaction conditions and the amount of adsorbent. The method has the advantages of being green, environmentally friendly, and low-cost, and provides a new strategy for environmental remediation and water treatment. The specific implementation steps of the method of the present invention include material preparation, adding the dosage to the CL-20-containing waste liquid and the reaction conditions, monitoring the change of CL-20 concentration, examining different solution concentrations, thermodynamic analysis, studying the maximum adsorption amount, exploring practical applications, expanding the scope of application, and optimizing process parameters. Through the above steps, the present invention provides an environmental remediation and water treatment technology with great potential.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for adsorbing CL-20 using silicic acid and sodium silicate, characterized in that: The following steps are involved: Adding a set dosage of adsorbent into the waste liquid containing CL-20; The adsorbent is silicic acid, sodium silicate or a mixture of the two; Under set conditions, the waste liquid after the adsorbent is added is stirred; The stirred solution was tested to measure the change in CL-20 concentration during the adsorption process, and the adsorption was completed.

2. A method for adsorbing CL-20 using silicic acid and sodium silicate according to claim 1, characterized in that: The silicic acid and sodium silicate need to be placed in an oven and dried at 105° C. for 2 hours before being added.

3. A method for adsorbing CL-20 using silicic acid and sodium silicate according to claim 1, characterized in that: The mass ratio of the mixture of silicic acid and sodium silicate is 1:(1-1.5).

4. A method for adsorbing CL-20 using silicic acid and sodium silicate according to claim 1, characterized in that: The set dosage of the adsorbent is 0.8-1.2 g / L.

5. The method for adsorbing CL-20 using silicic acid and sodium silicate according to claim 1, characterized in that: The set condition is 25° C. and stirring at a speed of 200 rpm for 12 hours.

6. A method for adsorbing CL-20 using silicic acid and sodium silicate according to claim 4, characterized in that: The stirred solution was separated by a 0.22 μm filter membrane, and the concentration of CL-20 in the supernatant was measured by high performance liquid chromatography to calculate the removal rate.

7. The method for adsorbing CL-20 using silicic acid and sodium silicate according to claim 1, characterized in that: The adsorption process is a non-spontaneous process of exothermic and entropy-reducing.

8. The method for adsorbing CL-20 using silicic acid and sodium silicate according to claim 1, characterized in that: The adsorption process is controlled by chemical adsorption.

9. The method for adsorbing CL-20 using silicic acid and sodium silicate according to claim 1, characterized in that: The CL-20 forms multi-layer adsorption on the surfaces of silicic acid and sodium silicate.

10. Use of the method for adsorbing CL-20 by using silicic acid and sodium silicate as claimed in any one of claims 1 to 9 in strongly acidic industrial wastewater containing CL-20.

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