An application method for removing petroleum hydrocarbon pollutants in soil by using cellulose nanocrystals

Abstract

The application provides a method for removing petroleum hydrocarbon pollutants in soil by using cellulose nanocrystals, and belongs to the technical field of pollution treatment. In the application, the cellulose nanocrystals are rod-shaped nanoparticles with high crystallinity and uniform particle size; the cellulose nanocrystals can interact with the petroleum hydrocarbon pollutants to form Pickering emulsion with high stability as a particle emulsifier; the cellulose nanocrystals are green, safe, non-polluting and have no influence on soil microorganisms when used for removing the petroleum hydrocarbon pollutants in soil; and the effect of the cellulose nanocrystals used in combination with a molecular surfactant is better than that of the molecular surfactant used alone.

Description

Technical Field

[0001] This invention relates to the field of pollution treatment technology, and in particular to an application method for removing petroleum hydrocarbon pollutants from soil using cellulose nanocrystals. Background Technology

[0002] With the rapid development of my country's industry, the extraction of crude oil is also increasing. During this process, oil spills and leaks occur frequently, making petroleum hydrocarbon pollution of soil a significant environmental problem. Soil is one of the essential environmental media for human survival, and petroleum hydrocarbon pollution poses a serious threat to soil structure, fertility, ecological structure, and groundwater. Therefore, developing and utilizing efficient soil petroleum hydrocarbon removal and remediation technologies is of great research significance and promise. Multiphase extraction technology has advantages such as low disturbance, wide range of action, high remediation efficiency, and the ability to treat high concentrations of organic pollution. It is widely used in the remediation of chlorinated organic compounds and petroleum pollution in petrochemical-contaminated sites and has high development potential. Optimization methods and innovative improvements are constantly emerging. This invention utilizes green solubilizing and desorbing materials to enhance the solubilization and desorption of non-aqueous liquids, resulting in better soil remediation effects.

[0003] Molecular surfactants, capable of altering surface tension, are among the most common solubilizing materials. However, the secondary pollution and threats to the environment and ecosystem caused by their extensive use cannot be ignored. These include affecting dissolved oxygen levels and nutrient ratios, leading to eutrophication of water bodies, altering soil physicochemical properties, and reducing soil fertility. Against this backdrop, exploring, developing, and utilizing low-toxicity and environmentally friendly solubilizing materials has become a key research focus.

[0004] In recent years, research on the stabilization of water-oil two-phase systems using solid particulate emulsifiers has attracted much attention. In the early 20th century, Ramsden and Pickering proposed using solid particles of colloidal size instead of molecular surfactants to stabilize immiscible two phases. Such particle-stabilized emulsions are generally called Pickering emulsions. In certain applications, they exhibit superior properties compared to emulsions stabilized with molecular surfactants, such as low emulsifier dosage, low toxicity, strong interfacial stability, and resistance to Austylene curing. In recent years, an increasing number of solid particles, such as inorganic particles, proteins, and polysaccharides, have been used as stabilizers in Pickering emulsions. Among these, cellulose nanocrystals are a widely available, non-toxic, harmless, and biocompatible polysaccharide particulate emulsifier. Cellulose nanocrystals possess unique amphiphilicity, nanoscale and nanostructure, extremely high chemical stability and biocompatibility, making them an ideal carrier for forming Pickering emulsions. When used as particulate emulsifiers, cellulose nanocrystals can form irreversible adsorption at the water-oil interface, creating single-layer or multi-layer interfaces that prevent collisions and aggregation between adjacent oil droplets, resulting in good stabilization and removal effects. Summary of the Invention

[0005] The purpose of this invention is to provide an application method for removing petroleum hydrocarbon pollutants from soil using cellulose nanocrystals. This invention utilizes cellulose nanocrystals for the removal of petroleum hydrocarbon pollutants from soil; the material is green and safe, and will not cause secondary pollution.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides an application of cellulose nanocrystals in the removal of petroleum hydrocarbon pollutants from soil.

[0008] This invention provides a method for removing petroleum hydrocarbon pollutants from soil using cellulose nanocrystals, comprising the following steps:

[0009] The soil to be treated is mixed with an organic solvent to obtain a slurry, wherein the soil to be treated contains petroleum hydrocarbon pollutants;

[0010] The slurry was mixed with a cellulose nanocrystal suspension for adsorption.

[0011] Preferably, the ratio of the cellulose nanocrystal suspension to the soil to be treated is 20-30 mL: 1 g, and the concentration of the cellulose nanocrystal suspension is 0.5-5 g / L.

[0012] Preferably, the organic solvent includes ethanol and / or acetone.

[0013] Preferably, the ratio of the soil to be treated to the organic solvent is 1g:1-10mL.

[0014] Preferably, the adsorption is carried out under oscillation conditions, wherein the oscillation frequency is 200-500 rpm and the time is 12-96 h.

[0015] Preferably, a molecular surfactant is also added during the adsorption process.

[0016] Preferably, the molecular surfactant includes one or more of sodium dodecylbenzenesulfonate, Triton X-100, and Tween-80.

[0017] Preferably, the mass ratio of cellulose nanocrystals to molecular surfactants in the cellulose nanocrystal suspension is 1:3 to 6:1.

[0018] This invention provides an application of cellulose nanocrystals in the removal of petroleum hydrocarbon pollutants from soil. In this invention, the cellulose nanocrystals are nanocellulose with a special structure, exhibiting high crystallinity and relatively uniform particle size. As a particulate emulsifier, the cellulose nanocrystals form a Pickering emulsion with high stability and biocompatibility. Applying cellulose nanocrystals to the removal of petroleum hydrocarbon pollutants from soil is green, safe, and pollution-free, and will not affect soil quality.

[0019] Furthermore, the adsorption process described in this invention also incorporates a molecular surfactant, combining cellulose nanocrystals with the molecular surfactant for better results than using the molecular surfactant alone. Attached Figure Description

[0020] Figure 1 C, D, and E correspond to the n-tetradecane removal rates in Examples 1, 2, and 3, respectively, while A and B correspond to the n-tetradecane removal rates in Comparative Examples 1 and 2, respectively. Detailed Implementation

[0021] This invention provides an application of cellulose nanocrystals in the removal of petroleum hydrocarbon pollutants from soil.

[0022] This invention provides a method for removing petroleum hydrocarbon pollutants from soil using cellulose nanocrystals, comprising the following steps:

[0023] The soil to be treated is mixed with an organic solvent to obtain a slurry, wherein the soil to be treated contains petroleum hydrocarbon pollutants;

[0024] The slurry was mixed with a cellulose nanocrystal suspension for adsorption.

[0025] Unless otherwise specified, all raw materials used in this invention are commercially available products in the field.

[0026] The present invention mixes the soil to be treated with an organic solvent to obtain a slurry, wherein the soil to be treated contains petroleum hydrocarbon pollutants.

[0027] In this invention, the petroleum hydrocarbon pollutants preferably include one or more of straight-chain hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, and polycyclic aromatic hydrocarbons, more preferably including light non-aqueous liquids and / or hydrocarbon liquids, wherein the hydrocarbon liquids preferably include gasoline and / or diesel; this invention does not specifically limit the source of the soil to be treated.

[0028] In this invention, the particle size of the soil to be treated is preferably 200 to 40 mesh.

[0029] In this invention, the organic solvent preferably includes ethanol and / or acetone.

[0030] In this invention, the preferred ratio of the soil to be treated to the organic solvent is 1g:1-10mL.

[0031] In this invention, the mixing is preferably performed once every 8 hours, and each stirring is performed by rotating the stirring wheel 10 times clockwise. This invention does not impose any special limitations on the stirring speed and time.

[0032] In this invention, the organic solvent is preferably added to the soil to be treated.

[0033] After obtaining the slurry, the present invention mixes the slurry with a cellulose nanocrystal suspension for adsorption.

[0034] In this invention, the preferred ratio of the cellulose nanocrystal suspension to the soil to be treated is 20-30 mL: 1 g, and the preferred concentration of the cellulose nanocrystal suspension is 0.5-5 g / L, more preferably 1-3 g / L.

[0035] In a specific embodiment of the present invention, the cellulose nanocrystals are preferably prepared by a formic acid-sulfuric acid mixing method.

[0036] In this invention, the adsorption is preferably carried out under oscillation conditions, the oscillation frequency is preferably 200-500 rpm, and the time is preferably 12-96 h.

[0037] In this invention, a molecular surfactant is preferably added during the adsorption process.

[0038] In this invention, the molecular surfactant preferably includes one or more of sodium dodecylbenzenesulfonate, Triton X-100, and Tween-80.

[0039] In this invention, the mass ratio of cellulose nanocrystals to nonionic molecular surfactants in the cellulose nanocrystal suspension is preferably 1:3 to 6:1.

[0040] After the adsorption is completed, the present invention preferably measures the content of petroleum hydrocarbon pollutants in the soil. The present invention does not have any special limitation on the measurement method, and any method known to those skilled in the art can be used. Specifically, gas chromatography can be used. When the petroleum hydrocarbon pollutant is preferably n-tetradecane, the measurement parameters of the gas chromatography method are preferably shown in Table 1.

[0041] Table 1. Parameters for the gas chromatography method for determining n-tetradecane.

[0042]

[0043] Example 1

[0044] The soil used in this experiment was farmland soil, which was air-dried for 96 hours, ground, and sieved. 1000g of soil was taken, and 5g of n-tetradecane was evenly mixed in 1000mL of acetone. The mixture was poured into the soil and stirred thoroughly to ensure uniform mixing. Stirring was performed every 8 hours over 168 hours, with each stirring done manually in a clockwise direction for 10 rotations, to obtain the contaminated soil.

[0045] The cellulose nanocrystals used in this experiment were prepared by a formic acid-sulfuric acid mixing method. They were initially stored in the form of a suspension with an initial concentration of 40 g / L. After dilution, the mass concentration of cellulose nanocrystals in the system reached 1.5 g / L. 20 mL of colloidal solutions of different concentrations were taken and mixed with 1 g of contaminated soil.

[0046] Shaking and mixing: The sample was embedded in a shaking incubator and shaken for 24 hours. After the shaking was completed, the sample was centrifuged and the content of n-tetradecane in the lower soil layer was determined by gas chromatography. The detection conditions are shown in Table 1.

[0047] Removal rate of n-tetradecane as follows Figure 1 As shown in C.

[0048] Example 2

[0049] The soil used in this experiment was farmland soil, which was air-dried for 96 hours, ground, and sieved. 1000g of soil was taken, and 5g of n-tetradecane was evenly mixed in 1000mL of acetone. The mixture was poured into the soil and stirred thoroughly to ensure uniform mixing. Stirring was performed every 8 hours over 168 hours, with each stirring done manually in a clockwise direction for 10 rotations, to obtain the contaminated soil.

[0050] The cellulose nanocrystals used in this experiment were prepared by a formic acid-sulfuric acid mixing method. They were initially stored in the form of a suspension with an initial concentration of 40 g / L. Based on a Tween-80 concentration of 1 g / L, appropriate amounts of cellulose nanocrystal suspensions were added to each to bring the mass concentration of cellulose nanocrystals in the system to 1.5 g / L. 20 mL of colloidal solutions of different concentrations were taken and mixed with 1 g of contaminated soil.

[0051] Shaking and mixing: The sample was embedded in a shaking incubator and shaken for 24 hours. After the shaking was completed, the sample was centrifuged and the content of n-tetradecane in the lower soil layer was determined by gas chromatography. The detection conditions are shown in Table 1.

[0052] Removal rate of n-tetradecane as follows Figure 1 As shown in D.

[0053] Example 3

[0054] The soil used in this experiment was farmland soil, which was air-dried for 96 hours, ground, and sieved. 1000g of soil was taken, and 5g of n-tetradecane was evenly mixed in 1000mL of acetone. The mixture was poured into the soil and stirred thoroughly to ensure uniform mixing. Stirring was performed every 8 hours over 168 hours, with each stirring done manually in a clockwise direction for 10 rotations, to obtain the contaminated soil.

[0055] The cellulose nanocrystals used in this experiment were prepared by a formic acid-sulfuric acid mixing method. They were initially stored in the form of a suspension with an initial concentration of 40 g / L. Based on a Tween-80 concentration of 3 g / L, appropriate amounts of cellulose nanocrystal suspension were added to each to bring the mass concentration of cellulose nanocrystals in the system to 1.5 g / L. 20 mL of colloidal solutions of different concentrations were taken and mixed with 1 g of contaminated soil.

[0056] Shaking and mixing: The sample was embedded in a shaking incubator and shaken for 24 hours. After the shaking was completed, the sample was centrifuged and the content of n-tetradecane in the lower soil layer was determined by gas chromatography. The detection conditions are shown in Table 1.

[0057] Removal rate of n-tetradecane as follows Figure 1 As shown in E.

[0058] Comparative Example 1

[0059] The soil used in this experiment was farmland soil, which was air-dried for 96 hours, ground, and sieved. 1000g of soil particles were taken, and 5g of tetradecane was evenly mixed in 1000mL of acetone. The mixture was poured into the soil and stirred thoroughly to ensure uniform mixing. Stirring was performed every 8 hours over 168 hours, with each stirring done manually in a clockwise direction for 10 rotations, to obtain the contaminated soil.

[0060] Blank rinse: Use clean water and mix it with 1g of contaminated soil.

[0061] Shaking and mixing: The sample was embedded in a shaking incubator and shaken for 24 hours. After the shaking was completed, the sample was centrifuged and the content of n-tetradecane in the lower soil layer was determined by gas chromatography. The detection conditions are shown in Table 1.

[0062] Removal rate of n-tetradecane as follows Figure 1 As shown in Figure A.

[0063] Comparative Example 2

[0064] The soil used in this experiment was farmland soil, air-dried for 96 hours, ground and sieved, retaining soil between 200 and 40 mesh. 1000g of soil particles were taken, and 5g of n-tetradecane was evenly mixed into 1000mL of acetone. This mixture was poured into the soil and thoroughly stirred to ensure uniform mixing. Stirring was performed every 8 hours for 168 hours, with each stirring done manually in a clockwise direction (10 revolutions) to obtain the contaminated soil.

[0065] The comparative material used was Tween-80 alone, diluted with water to 1 g / L. 20 mL of Tween-80 solution was taken and mixed with 1 g of contaminated soil.

[0066] Shaking and mixing: The sample was embedded in a shaking incubator and shaken for 24 hours. After the shaking was completed, the sample was centrifuged and the content of n-tetradecane in the lower soil layer was determined by gas chromatography. The detection conditions are shown in Table 1.

[0067] Removal rate of n-tetradecane as follows Figure 1 As shown in B.

[0068] Depend on Figure 1 It is known that the present invention applies cellulose nanocrystals to the removal of petroleum hydrocarbon pollutants in soil. It is effective in removing petroleum hydrocarbons in soil when used alone, and the effect is stronger when used with molecular surfactants at a certain concentration ratio. Experiments show that the removal effect of petroleum hydrocarbons in soil is effectively improved in the low dose addition group.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles 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 method for removing petroleum hydrocarbon pollutants from soil using cellulose nanocrystals, characterized in that, Includes the following steps: The soil to be treated is mixed with an organic solvent to obtain a slurry, wherein the soil to be treated contains petroleum hydrocarbon pollutants; the petroleum hydrocarbon pollutant is n-tetradecane; The slurry was mixed with a cellulose nanocrystal suspension for adsorption. The ratio of the cellulose nanocrystal suspension to the soil to be treated is 20 mL: 1 g, the concentration of the cellulose nanocrystal suspension is 1.5 g / L, and a molecular surfactant, Tween-80, is added during the adsorption process at a concentration of 3 g / L.

2. The application method according to claim 1, characterized in that, The organic solvents include ethanol and / or acetone.

3. The application method according to claim 1 or 2, characterized in that, The ratio of the soil to be treated to the organic solvent is 1g:1-10mL.

4. The application method according to claim 1, characterized in that, The adsorption is carried out under oscillation conditions, with an oscillation frequency of 200–500 rpm and a duration of 12–96 h.

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