An environmentally friendly desorption material for efficient remediation of chlorinated hydrocarbon-contaminated aquifers and a preparation method thereof

Abstract

The application relates to an environment-friendly desorption material for efficiently repairing chlorinated hydrocarbon contaminated aquifers. The total mass of the desorption material is used as a basis, and the desorption material comprises the following components: 1.0 wt.% alkyl polyglycoside (APG) 1214, 5.6 wt.% co-surfactant, and 0.8 wt.% sodium chloride, wherein the co-surfactant is composed of n-propanol and isobutyl alcohol at a mass ratio of 1:1. The prepared desorption material has a wide environmental application range, a low surfactant dosage, and high desorption performance. The alcohol of the composite alcohol desorption material is wide, the particle size is small, and the interfacial tension is small; the desorption rate of in-situ leaching PCE reaches 99.4%, which is 68% higher than that of single surfactant (1.0 wt.% APG1214) at the same temperature; the primary biodegradation degree of the surfactant APG1214 reaches 90.27% at 163 h, and the secondary pollution generated in the repair process is small.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental engineering, and particularly relates to a high-efficiency desorption material, and particularly relates to an environmentally friendly desorption material with low surfactant dosage and high efficiency in removing chlorinated hydrocarbons in aquifer, and a preparation method thereof. BACKGROUND

[0002] Chlorinated hydrocarbons, as a common chemical material, are widely used in industrial cleaning and clothes degreasing fields, and have potential toxicity of carcinogenicity, teratogenicity and mutagenicity. Most of the chlorinated hydrocarbons enter the groundwater through unreasonable discharge, leakage in waste accumulation sites, chemical leakage and other ways, polluting the groundwater environment and being listed as priority pollutants by various countries. At present, there are chlorinated hydrocarbon contaminated sites in many countries in the world. In 2000, the total amount of perchloroethylene (PCE) used in the dry cleaning industry in the United States was 91,000 tons. As of 2021, the groundwater of chemical sites in the Lubei Plain, the Pearl River Delta region, Beijing, Shanghai and other places has been contaminated by PCE to varying degrees, and the pollution range is expanding.

[0003] The surfactant enhanced aquifer remediation (SEAR) technology injects surfactant solution into the underground aquifer to enhance the solubility and flowability of pollutants, so that the residual phase chlorinated hydrocarbons in the aquifer medium are gradually converted into the dissolved phase, effectively improving the remediation efficiency. SEAR technology shows great application potential in environmental remediation practice, but an important problem that is ignored is that the desorption capacity of a single surfactant solution for chlorinated hydrocarbons is limited, and the use of surfactants to remove chlorinated hydrocarbons in contaminated aquifers will form emulsions, which are not stable in the body system. In contrast, the desorption material composed of surfactants, co-surfactants and salts has high desorption performance and low interfacial tension, and the microemulsion system formed when removing chlorinated hydrocarbons is more stable. Alkyl alcohol is usually selected as a co-surfactant, however, adding a single alkyl alcohol as a co-surfactant may have problems of large dosage, small alcohol width of the system and limited microemulsification performance, which affects the environmental applicability and desorption performance of the desorption material. CN202010786101.1 discloses a microemulsion preparation method using non-ionic surfactant Tween 80, and specifically discloses a material formed by mixing 10-16% Tween 80 and 10-24% co-surfactant and the like, and the maximum solubilization concentration of PCE is 296g / L. The material prepared by the invention has a high dosage of surfactants and other substances, and the solubilization performance needs to be improved.

[0004] Therefore, it is very crucial to develop an environmentally friendly material suitable for aquifer remediation, which has a wide environmental application range, low surfactant dosage and high desorption performance.

[0005] The present application develops a low-surfactant, wide-environmental-application, high-desorption-performance, environment-friendly remediation reagent for chlorinated hydrocarbon by adjusting the type and ratio of co-surfactants in the desorption material. SUMMARY

[0006] In view of the problems of large amount of surfactant, poor pollutant removal performance, and secondary pollution in the process of leaching remediation of contaminated aquifer, the present application provides an environment-friendly desorption material for efficient remediation of chlorinated hydrocarbon contaminated aquifer and a preparation method thereof. The present application is suitable for remediation of PCE contaminated aquifer, has less surfactant, good biodegradability, and excellent desorption performance.

[0007] The technical solution of the present application is as follows:

[0008] An environment-friendly desorption material for efficient remediation of chlorinated hydrocarbon contaminated aquifer, based on the total mass of the desorption material, comprises the following components: 1.0wt.% of green non-ionic surfactant; 2-20wt.% of co-surfactant; 0.5-1.5wt.% of inorganic salt; and the rest is deionized water.

[0009] The green non-ionic surfactant is alkyl polyglycoside (APG) 1214.

[0010] The co-surfactant is selected from alkyl alcohols with carbon number of 2-4, such as ethanol, n-propanol, isopropanol, n-butanol, isobutanol, etc., preferably n-propanol and isobutanol.

[0011] The inorganic salt is selected from sodium chloride, potassium chloride, and calcium chloride, preferably sodium chloride.

[0012] In addition, the APG 1214 is 1.0wt.%, the n-propanol:isobutanol (1:1) is 5.6wt.%, and the sodium chloride is 0.8wt.%.

[0013] The preparation method of the above-mentioned environment-friendly desorption material for efficient remediation of chlorinated hydrocarbon contaminated aquifer comprises the following steps:

[0014] Based on the total mass of the desorption material, 1.0wt.% of APG 1214, 2-20wt.% of n-propanol and isobutanol, and 0.5-1.5wt.% of sodium chloride are added to deionized water and mixed uniformly.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] 1. The desorption material prepared by the present application uses green surfactant APG 1214, which is processed from renewable resources, non-toxic, easily biodegradable, has good biodegradability, and has less amount.

[0017] 2、The prepared desorption material of the application is simple in component, easy to operate, low in requirement for equipment and low in cost.

[0018] 3、The prepared desorption material of the application uses n-propanol and isobutyl alcohol for 1:1 compounding as a co-surfactant, the two components synergistically act, the desorption material can efficiently desorb PCE, has suitable alcohol width and greater desorption effect, and the performance is superior to that of single alcohol desorption material.

[0019] 4、The prepared desorption material of the application is extremely low in surfactant dosage, has good desorption effect on PCE, the static desorption amount of PCE is 558 g / L, and the PCE desorption amount is increased by 97 times compared with that of a single surfactant system (1.0 wt.% APG1214) at the same temperature.

[0020] 5、The in-situ leaching desorption rate of PCE of the prepared composite alcohol desorption material of the application can reach 99.4%, and the PCE desorption rate is increased by 68% compared with that of a single surfactant system (1.0 wt.% APG1214) at the same temperature. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to make the purpose, technical scheme and advantages of the application more clear, the preferred detailed description of the application will be made below in combination with the drawings, in which:

[0022] Figure 1 It is an alcohol degree scanning phase distribution schematic diagram of the composite alcohol system in the embodiment 4 of the application;

[0023] Figure 2 It is an alcohol degree scanning phase distribution schematic diagram of the n-propanol system in the embodiment 4 of the application;

[0024] Figure 3 It is an alcohol degree scanning phase distribution schematic diagram of the isobutyl alcohol system in the embodiment 4 of the application;

[0025] Figure 4 It is a particle size distribution diagram of the desorption material in the embodiment 7 of the application;

[0026] Figure 5 It is a PCE removal amount change diagram with desorption material injection PV in the embodiment 10 of the application. DETAILED DESCRIPTION

[0027] The embodiments of the application are described below through specific specific examples, and other advantages and effects of the application can be easily understood by those skilled in the art from the disclosure of the specification.

[0028] Embodiment 1

[0029] An environment-friendly desorption material for efficiently repairing chlorinated hydrocarbon contaminated aquifer, comprising the following components based on the total mass of the desorption material: 1.0 wt.% APG1214, 5.6 wt.% co-surfactant, and 0.8 wt.% sodium chloride. The co-surfactant is a composite of n-propanol and isobutanol in a mass ratio of 1:1.

[0030] The preparation process is as follows: based on the total mass of the desorption material, the above-mentioned mass fractions of APG1214, n-propanol, isobutanol, and sodium chloride are added to deionized water, and the mixture is inverted and uniformly mixed.

[0031] Example 2

[0032] A desorption material for repairing chlorinated hydrocarbon contaminated aquifer, which has substantially the same components as in Example 1, except that the co-surfactant is only n-propanol, the concentration of n-propanol is 14 wt.%, and the concentration of sodium chloride is 0.5 wt.%.

[0033] The preparation process is as follows: based on the total mass of the desorption material, the above-mentioned mass fractions of APG1214, n-propanol, and sodium chloride are added to deionized water, and the mixture is inverted and uniformly mixed.

[0034] Example 3

[0035] A desorption material for repairing chlorinated hydrocarbon contaminated aquifer, which has substantially the same components as in Example 1, except that the co-surfactant is only isobutanol, the concentration of isobutanol is 3.1 wt.%, and the concentration of sodium chloride is 1.0 wt.%.

[0036] The preparation process is as follows: based on the total mass of the desorption material, the above-mentioned mass fractions of APG1214, isobutanol, and sodium chloride are added to deionized water, and the mixture is inverted and uniformly mixed.

[0037] Example 4

[0038] The alcohol width of the desorption materials in Examples 1-3 for efficiently desorbing PCE is determined. PCE is added to the desorption material in a mass ratio of 1:1 with deionized water, the mixture is inverted and uniformly mixed, then placed in a 20°C constant temperature box, inverted and mixed again after 1h, and placed in the constant temperature box for 48h. The concentrations of surfactant and salt in the system are fixed, and the alcohol concentration is scanned to record the highest and lowest alcohol concentrations required for the desorption material to efficiently desorb PCE, as shown in Table 1. The alcohol widths of the three desorption materials are 4.0-6.1 wt.%, 12-18 wt.%, and 2.5-3.3 wt.% respectively. Compared with n-propanol, the composite alcohol desorption material requires a lower alcohol concentration; compared with isobutanol, the composite alcohol desorption system has a wider alcohol width, which is conducive to the efficient desorption of PCE in the aquifer environment and has a wide environmental applicability. Figures 1-3 ​

[0039] Table 1 - required alcohol width for different desorption materials

[0040]

[0041] Example 5

[0042] The desorption performance of the desorption materials in Examples 1-3 on PCE was determined, PCE with a mass ratio of 1:1 to deionized water was added to the desorption material, and after mixing upside down, it was placed in a 20°C constant temperature box, and after standing for 1h, it was again mixed upside down and placed in a constant temperature box for 48h. The concentration of PCE in the sample was determined using a Shimadzu LC-40D high performance liquid chromatograph, and the results are shown in the table below. The static desorption concentration of PCE of the composite alcohol and single alcohol (n-propanol, isobutyl alcohol) desorption material was 558g / L, 423g / L, 472g / L, respectively, wherein the composite alcohol desorption material was 97 times higher than the PCE desorption amount of the single surfactant system (1.0wt.% APG1214) at the same temperature.

[0043] Table 2 - PCE desorption concentration of different desorption materials

[0044]

[0045] Example 6

[0046] The Zeta potential of the desorption materials in Examples 1-3 was determined, the measuring instrument was a Malvern ZS910 type, and the Zeta potential of the composite alcohol and single alcohol (n-propanol, isobutyl alcohol) desorption material was -1.5mV, -1.4mV, -1.4mV, respectively. There is electrostatic repulsion between the negatively charged desorption material and the negatively charged aqueous layer medium, and the adsorption loss generated during the aqueous layer transmission process is small.

[0047] Table 3 - Zeta potential of different desorption materials

[0048]

[0049] Example 7

[0050] The particle size of the desorption materials in Examples 1-3 was determined, the measuring instrument was a Malvern Mastersizer2000, and the particle size test results of the composite alcohol and single alcohol (n-propanol, isobutyl alcohol) desorption material are shown in Table 4, the particle size was 20.7nm, 15.3nm, 31.7nm, respectively, indicating that the droplets of the three desorption materials can effectively pass through the pore of the aqueous layer; the PDI was 0.232, 0.044, 0.044, respectively, indicating that the desorption material is uniformly dispersed. Figure 4 Table 4 - particle size of different desorption materials

[0051]

[0052] ​

[0053] Example 8

[0054] The interfacial tension between the desorption materials in Examples 1-3 and PCE was determined, and the determination instrument was a rotating drop interfacial tension meter KRUSS SDT. The interfacial tension of the composite alcohol and single alcohol (n-propanol, isobutanol) desorption materials was 0.353 mN / m, 0.311 mN / m, and 0.449 mN / m, respectively.

[0055] Table 5 - Interfacial tension between different desorption materials and PCE

[0056]

[0057] Example 9

[0058] The biodegradability of the surfactant APG1214 used in the desorption material in Example 1 was determined, and the reference standard was GB / T 15818-2018 “Test method for biodegradability of surfactants”. The biodegradability of APG1214 within the specified time is shown in Table 6. The biodegradability of APG1214 was higher than 90% in 6-7 days, proving that the environmentally friendly desorption material prepared in the present application for efficient remediation of chlorinated hydrocarbon contaminated aquifers has environmental friendliness.

[0059] Table 6 - Biodegradability of APG1214

[0060]

[0061] Example 10

[0062] The in-situ leaching PCE pollution remediation effect of the desorption materials in Examples 1-3 was determined. The simulation column was 13 cm in length and 2 cm in inner diameter, filled with 0.1-0.25 mm river sand, and after being saturated with water, 2.4 mL of PCE was injected. The desorption material was injected into the simulation column at a flow rate of 0.5 mL / min from the bottom, and the effluent was collected at certain time intervals to determine the PCE concentration in the effluent. The total removal amount and total desorption rate of PCE are shown in Table 7. Figure 5 , and the total desorption rate of PCE of the desorption materials was: composite alcohol desorption material > isobutanol desorption material > n-propanol desorption material > 1.0 wt.% APG1214. The total desorption rate of PCE of the composite alcohol desorption material reached 99.4%, proving that the environmentally friendly desorption material prepared in the present application for efficient remediation of chlorinated hydrocarbon contaminated aquifers has high desorption performance.

[0063] Table 7 - Total removal amount and total desorption rate of PCE of different desorption materials

[0064]

[0065] The present application is found that the composite alcohol desorption material has better effect on in-situ leaching PCE contaminated aquifer than single alcohol desorption material even under low surfactant dosage (1.0wt.% APG1214) by screening the composite of co-surfactant component, which shows that the synergistic effect of n-propanol and isobutyl alcohol, and the lack of either one will lead to the defect of desorption material performance.

[0066] It can be seen from the above test results that the desorption material is composed of the following components: 1.0wt.% APG1214, 5.6wt.% co-surfactant, 0.8wt.% sodium chloride, wherein the co-surfactant is a composite of n-propanol and isobutyl alcohol, and the mass ratio of the two is 1:1, the desorption material has excellent performance, and has outstanding desorption performance on PCE under low surfactant dosage, which is 68% higher than the in-situ leaching PCE desorption rate of single surfactant system (1.0wt.% APG1214) at the same temperature.

Claims

1. An environmentally friendly desorption material for the efficient remediation of chlorinated hydrocarbon-contaminated aquifers, comprising, based on the total mass of the desorption material: 1.0 wt.% nonionic surfactant, 5.6 wt.% co-surfactant, 0.8 wt.% inorganic salt, with the remainder being deionized water; wherein the nonionic surfactant is alkyl glycoside APG1214; the co-surfactant is n-propanol and isobutanol; the inorganic salt is sodium chloride; and the mass ratio of n-propanol to isobutanol is 1:1; the preparation of the desorption material includes the following steps: Add alkyl glycoside APG1214, n-propanol and isobutanol, and sodium chloride to deionized water, and mix thoroughly by inverting the mixture.

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