Rare earth Sm-based composite nanomaterial for capturing glyphosate in water environment

Abstract

The invention particularly relates to a rare earth Sm-based composite nanomaterial for capturing glyphosate in a water environment. A preparation method of the rare earth Sm-based composite nanomaterial comprises the following preparation steps: S1, synthesizing Fe3O4 through a coprecipitation method; s2, preparing a composite material Fe3O4 / GO of Fe3O4 and GO; and S3, preparing Fe3O4 / GO / Sm (OH) CO3 by using urea through slightly modified chemical homogeneous precipitation.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of glyphosate adsorbents, and particularly relates to a rare earth Sm-based composite nanomaterial for capturing glyphosate in the water environment. Background Art

[0002] With the advancement of the industrialization process, new pollutants such as heavy metals, personal care products (PCPs), pesticides, antibiotics, and particulate matter have been introduced into the environment, leading to the escalation of aquatic ecological environment pollution. Among these newly emerging pollutants, pesticides are the most widely used in soil, aquatic, and biological systems. Glyphosate (N-(phosphonomethyl)glycine, Gly) is a typical organophosphorus pesticide and an ideal herbicide for controlling weeds and optimizing agricultural production because it can disrupt the structures of microorganisms and invasive herbs that affect production. However, the utilization rate of glyphosate pesticides in actual applications is low, resulting in glyphosate remaining in the soil and then migrating to waterways and aquifers through agricultural drainage systems, causing harm to the water environment. It is considered the most widely used herbicide in the world and one of the most harmful herbicides to human health. However, as an emerging pollutant, the pollution of glyphosate in water bodies is a health problem due to its potential cytotoxicity, mutagenicity, blood toxicity, and carcinogenic properties. The presence of glyphosate in the environment has prompted researchers to develop rapid and effective removal methods to purify water resources. Although the scientific community has studied several methods for removing Gly from environmental water, including chemical coagulation, oxidation, activated carbon adsorption, membrane treatment, and biodegradation, there is still no consensus on which method is the most promising in terms of its removal efficiency and environmental footprint.

[0003] Adsorption is a simple and effective method for capturing ethylene glycol from wastewater, with characteristics such as flexibility, easy operation, and high efficiency, and is considered a promising technology. Generally speaking, in the adsorption process, the separation operation is crucial for separating the adsorbent from the aqueous solution. However, centrifugation or filtration operations have the disadvantages of being cumbersome and time-consuming, severely limiting practical applications. When the pollutant adsorption process is completed, magnetic separation has become a very rapid technology for separating magnetic adsorbents from the medium. At the same time, the recovery of the adsorbent by magnetic separation technology can reduce the residue of adsorbed substances in the environment. For example, Rallet et al. developed clay biochar to adsorb Gly, and separated the mixture of the adsorbent and Gly through Whatman filter paper, which increased the cost and time of treatment, while Munise et al. designed Fe3O4-modified coffee husk biochar to remove Gly and separated the adsorbent with the help of a magnet, greatly saving cost and time. In addition, magnetic biochar can be reused multiple times and recovered by a magnet, thereby reducing the risk of secondary pollution to the environment.

[0004] Magnetic nano-Fe3O4 is a common magnetic carrier with low adsorption efficiency and dispersibility. To improve the adsorption capacity for glyphosate, Fe3O4 was modified by graphene oxide (GO) with a larger specific surface area and abundant functional groups (-COOH, -OH), achieving rapid separation and high adsorption performance. Based on this hypothesis, Santos et al. successfully constructed a GO-α-γ-Fe2O3 adsorbent with an adsorption capacity for Gly of 46.8 mg / g. However, further efforts are needed to improve the adsorption capacity of Fe3O4 and GO composites for Gly.

[0005] In recent years, there have been more and more samarium rare earth materials, such as samarium oxide (Sm2O3), samarium hydroxide (Sm(OH)3), and basic samarium carbonate (Sm(OH)CO3). However, there is currently no research report on using samarium rare earth materials as adsorbents to adsorb pollutants from the aquatic environment. Interestingly, some studies have shown that Sm 3+ and other metal ions are prone to binding with phosphate groups due to affinity interactions to form phosphates or metaphosphates with excellent optoelectronic properties, which has attracted extensive attention in the fields of optics, electricity, and magnetism. This valuable information provides new insights into the application of Sm-based rare earth materials in removing Gly, highlighting the innovation of this work.

[0006] In this study, we proposed a novel multifunctional fragmented two-dimensional magnetic Fe3O4 / GO / Sm(OH)CO3 (FGS) nanocomposite. The possible formation mechanism of fragmented FGS was preliminarily explored. On the one hand, the mechanism of Sm(OH)CO3 deposition on Fe3O4 / GO is that Sm 3+ combines with CO3 2- and OH - ions, which are uniformly generated by slowly releasing urea in the solution; on the other hand, the CO3 3+ and OH 2- ions interacting with Sm - are provided by C=O, C-OH, and C-O-C on GO, resulting in the fishnet-like GO being torn into a fragmented structure. In addition, sheet-like, rhombic, and bipyramidal Sm(OH)CO3 have been successfully excavated, but the morphology of Sm(OH)CO3 combined with other materials has not been reported. In addition, FGS has the advantages of integrated magnetic properties and two-dimensional large specific surface area, as well as Sm 3+ for PO4 3-The special affinity should be a promising rapid magnetic separation Gly capturer in the aquatic environment. The proposed alternative magnetic adsorbent (Fe3O4 / GO / Sm(OH)CO3, FGS) was successfully synthesized and used for the first time to adsorb glyphosate in water. In addition, batch adsorption experiments of the FGS adsorbent for Gly will be carried out to evaluate its adsorption capacity. The adsorption effect was verified by the combination of the nitrite method and the UV-1100 ultraviolet spectrophotometer, providing a basis for the removal, analysis, and determination of emerging pollutants in Sm-based materials. Summary of the Invention

[0007] The object of the present invention is to provide a rare earth Sm-based composite nanomaterial for capturing glyphosate in the water environment to solve the problems existing in the background technology.

[0008] To achieve the above technical object, the technical solution adopted by the present invention is as follows:

[0009] A rare earth Sm-based composite nanomaterial for capturing glyphosate in the water environment, comprising the following preparation steps:

[0010] S1: Synthesize Fe3O4 by the co-precipitation method;

[0011] S2: Prepare the composite material Fe3O4 / GO of Fe3O4 and GO;

[0012] S3: Use urea to prepare Fe3O4 / GO / Sm(OH)CO3 by slightly modified chemical homogeneous precipitation.

[0013] Preferably, when synthesizing Fe3O4, 0.556 g of FeSO4·7H2O and 1.082 g of FeCl3·6H2O are added to 40 mL of distilled water, and then 3 mL of ammonia is injected into the mixed solution to adjust the pH to 11. The obtained solution is stirred at 40 °C for 20 min. The final nano-Fe3O4 product is collected by magnetic assistance, washed with deionized water, and then dried at 60 °C and ground before use.

[0014] Preferably, when preparing Fe3O4 / GO, 20 mg of GO is ultrasonically dispersed in 25 mL of distilled water for 30 min of ultrasonic treatment. 0.1 g of the above-prepared nano-Fe3O4 is added. Then the whole mixture is transferred to a three-necked flask at 60 °C under mechanical stirring for 1 h. The solid nano-composite material Fe3O4 / GO is separated by an external magnet, washed with deionized water until neutral, and dried at 60 °C for 12 h.

[0015] Preferably, when preparing Fe3O4 / GO / Sm(OH)CO3, 50 mg of Fe3O4 / GO was dispersed in 200 mL of distilled water under ultrasonic treatment, then 1.5 g of urea was added. After 10 min, Sm(NO3)3·6H2O was added and maintained in an ultrasonic water bath. The pH value of the mixed solution was adjusted to 5 with a small amount of ammonia water. The reaction was carried out at 90 °C for 2 h. The final precipitate was washed several times with distilled water and absolute ethanol, and dried overnight at 60 °C.

[0016] In this invention, a new type of multifunctional fragmented two-dimensional magnetic rare-earth Sm-based material Fe3O4 / GO / Sm(OH)CO3 was synthesized, and glyphosate (Gly) was selected as the adsorption object to conduct a series of experiments to explore the adsorption performance of FGS. The multifunctionality of FGS is manifested in: 1) Its excellent magnetism enables Gly to be rapidly magnetically separated from the aquatic environment, saving time and cost; 2) The two-dimensional structure of the fragmented FGS endows them with a large specific surface area, providing more adsorption sites for Gly; 3) Due to the interaction between Sm 3+ and PO4 3- for the first time, magnetic Sm(OH)CO3 with high affinity was used as an adsorbent for Gly. By changing the experimental parameters, including the initial concentration and pH value of the Gly solution, the adsorbent dosage, and the contact time, the optimal adsorption conditions were determined, and the coexisting ion competition effect, the regenerability of the adsorbent, and the isothermal adsorption performance parameters were further studied. All experimental results show that the FGS material has excellent adsorption capacity for Gly, and its adsorption behavior can better follow the Langmuir isotherm model. The synthesized magnetic rare-earth material FGS is proven to be a potential adsorbent that can effectively remove Gly from actual wastewater and is expected to play a role in the water purification process. Description of the Drawings

[0017] This invention can be further illustrated by the non-limiting examples given in the drawings.

[0018] Figure 1 is the synthesis process of Fe3O4 / GO / Sm(OH)CO3 (FGS);

[0019] Figure 2 Column comparison chart;

[0020] Figure 3 is the effect of the dosages of Fe3O4, Fe3O4 / GO, and FGS on the adsorption of Gly;

[0021] Figure 4 is the acid-base form and acid dissociation equilibrium constant of Gly;

[0022] Figure 5 is the pH pzc value of FGS;

[0023] Figure 6 It is the regeneration performance investigation diagram of the adsorption of Gly by FGS;

[0024] Figure 7 It is the isothermal adsorption curve diagram;

[0025] Figure 8 It is the Langmuir and Freundlich adsorption isotherm parameter diagram of Fe3O4, FG and FGS for Gly;

[0026] Figure 9 It is the comparison diagram of the maximum theoretical adsorption capacity of existing adsorbents for Gly; Specific implementation mode

[0027] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0028] A rare earth Sm-based composite nanomaterial for capturing glyphosate in water environment of the present invention includes the following preparation steps:

[0029] S1: Synthesize Fe3O4 by co-precipitation method;

[0030] S2: Prepare the composite material Fe3O4 / GO of Fe3O4 and GO;

[0031] S3: Use urea to prepare Fe3O4 / GO / Sm(OH)CO3 by slightly modified chemical homogeneous precipitation.

[0032] Fe3O4 was synthesized by co-precipitation method. 0.556 g of FeSO4·7H2O and 1.082 g of FeCl3·6H2O (nFe 2+ :nFe 3+ = 1:2) were added to 40 mL of distilled water, and then 3 mL of ammonia was injected into the mixed solution to adjust the pH to 11. The obtained solution was stirred at 40 °C for 20 min. The final nano-Fe3O4 product was collected by magnetic assistance, washed with deionized water for several times, and then dried at 60 °C and ground before use.

[0033] Before adding 0.1 g of the above-prepared nano-Fe3O4, 20 mg of GO was ultrasonically dispersed in 25 mL of distilled water for 30 min. Then the whole mixture was transferred to a three-necked flask at 60 °C under mechanical stirring for 1 h. The solid nanocomposite material (FG) was separated by an external magnet, washed with deionized water until neutral, and dried at 60 °C for 12 h.

[0034] Fe3O4 / GO / Sm(OH)CO3 (denoted as FGS) was prepared by slightly modified chemical homogeneous precipitation using urea. 50 mg of FG was dispersed in 200 mL of distilled water under ultrasonic treatment, and then 1.5 g of urea was added. After 10 min, Sm(NO3)3·6H2O (0.888 g, 2 mmol) was added and kept in an ultrasonic water bath. The pH value of the mixed solution was adjusted to 5 with a small amount of ammonia water, and the reaction was carried out at 90 °C for 2 h. The final precipitate was washed several times with distilled water and absolute ethanol and dried overnight at 60 °C. The reaction process for the formation of Sm(OH)CO3 can be described as follows:

[0035] CO(NH2)2 + 3H2O → CO2 + 2NH3·H2O

[0036] NH3 + H2O → NH4 + + OH -

[0037] Sm 3+ + OH - + CO3 2- → Sm(OH)CO3

[0038] The synthesis process of FGS is as Figure 1 shown;

[0039] Adsorption experiment: The adsorption behaviors of Fe3O4, Fe3O4 / GO (FG), and Fe3O4 / GO / Sm(OH)CO3 (FGS) composites on glyphosate (Gly) were studied by batch experiments; experimental parameters such as the pH value and initial concentration of the Gly solution, contact time, and adsorbent dosage were adjusted to determine the optimal adsorption conditions; in short, a certain concentration of adsorbent was prepared, 50 μL of the adsorbent was transferred into 500 μL of Gly solutions with different concentrations, and then placed in a constant-temperature oscillation chamber for 1 h. The adsorbent captured by Gly was separated by a magnet, and the supernatant concentration of Gly was measured by UV 1100 spectrophotometry (λ max = 242 nm) using the in-station method, and the adsorption capacity (Q t ) of the adsorbent composite for Gly was calculated using Equation (1). The removal rate (R) of Gly by the adsorbent can be calculated by Equation (2).

[0040] Q t = (C0 - C t )V / m (1)

[0041] R = (C0 - C t ) / C0 × 100% (2)

[0042] where C0 and C t(mg / L) represents the concentration of Gly in the solution before and after adsorption (at time t); V (mL) is the initial volume of the Gly solution; m (g) is the amount of adsorbent added, equal to m = C a V a (C a represents the concentration of the adsorbent, and V a is the volume of the adsorbent).

[0043] Adsorption isotherm: The isothermal adsorption experiment can be used to evaluate the adsorption capacity of the adsorbent for Gly when adsorption - desorption reaches equilibrium at different initial Gly concentrations; while keeping other factors unchanged, the initial concentration of Gly is changed to 50, 100, 350, 500, 800, and 1000 mg / L with 0.125 mg; the adsorption is carried out for 70 min in a constant - temperature shaking chamber, and when equilibrium is reached (70 min), the adsorption amount of Gly is calculated, and the results are fitted and analyzed using the Langmuir equation (3) and Freundlich equation (4) isotherm models.

[0044] Q e =(K L ·q max ·C e ) / (1 + K L ·C e ) (3)

[0045] lnQ e =lnK F +(1 / n)·lnC e (4)

[0046] Where C e represents the concentration of Gly at equilibrium (mg / L); K L (L / mg) is the Langmuir constant, representing the adsorption energy; q max (mg / g) represents the maximum Langmuir theoretical adsorption capacity; K F (mg / g) and n are Freundlich constants, related to the adsorption capacity and adsorption density respectively.

[0047] Desorption of glyphosate and regeneration performance of the adsorbent: Reusable adsorbents can reduce the cost of wastewater treatment. To evaluate the reproducibility of the FGS composite, ammonia is selected as the desorbent to elute Gly from the FGS adsorbent loaded with Gly. Briefly, 0.125 mg of FGS is immersed in 500 μL of 350 mg / L Gly solution and shaken for 70 min. Therefore, due to the Sm on the surface of FGS 3+There is a strong specific affinity between the carboxyl group of Gly and the phosphate group, and Gly is captured on the surface of the FGS material; subsequently, by adding 1 mL of NH₃·H₂O solution, after ultrasonic treatment for 5 min, the bare FGS eluting Gly is collected with the aid of a magnet. The bare FGS is washed 3 - 5 times with distilled water and absolute ethanol, and then dried at 60 °C for the next cycle. After the adsorption process is completed for the same batch of bare FGS in 4 repeated cycles, the Gly adsorption capacity is compared each time to evaluate its regeneration performance.

[0048] 1. Batch experiment:

[0049] 0.15 mg of Fe₃O₄, FG, and FGS were respectively placed into 500 μL of 300 mg / L glyphosate (Gly) solution. After 1 h of contact reaction in a constant-temperature shaking chamber, the residual amount of Gly in the supernatant was measured at λ = 242 nm by nitrosation ultraviolet spectrophotometry. The adsorption capacities of the three adsorbents for Gly were calculated, and the results are as Figure 2 shown in A. It is worth noting that compared with Fe₃O₄ (Q = 41.88 mg / g) and FG (Q = 35.64 mg / g), FGS has the highest adsorption capacity (Q = 67.51 mg / g) due to its superior adsorbent layer of Sm(OH)CO₃. These results firmly confirm that Sm(OH)CO₃ plays a crucial role in the adsorption of Gly. To verify the adsorption performance of FGS, Fe₃O₄ and FG were used as a comparison in subsequent batch experiments.

[0050] Figure 2 A) Adsorption capacities of Fe₃O₄, FG, and FGS for Gly; B) Influence of adsorbent dosage on Gly adsorption; C) Influence of initial Gly concentration on adsorption; D) Influence of different pH values on Gly adsorption; E) Influence of contact time on Gly adsorption; F) Influence of different coexisting ions on Gly adsorption.

[0051] 2. Optimization of adsorption conditions:

[0052] ①. Dosage of adsorbent: The dosage of adsorbent (m) is a key factor affecting the adsorption process. Therefore, when the initial Gly concentration is 300 mg / L, the influence of the dosages of Fe₃O₄, FG, and FGS adsorbents on the Gly adsorption capacity was studied in the range of 1.0 - 4.0 g / L. As Figure 2 shown in B, the adsorption capacity of FGS for Gly gradually decreases with the increase in the adsorbent dosage. However, in the range of 0.05 mg to 1.0 g / L and up to 0.125 mg, the adsorption rate increases with the increase in the FGS dosage (the relationship between the adsorption rate (R%) and the material dosage is as Figure 3As shown. When the dosage exceeds 0.125 mg to 4.0 g / L, the adsorption rate tends to balance. The possible reason is that when the added adsorbent dosage is small and the volume and concentration of the Gly solution are constant, all the active sites of the adsorbent are occupied by Gly, but complete adsorption cannot be achieved. As the dosage of the adsorbent gradually increases, superposition or blockage occurs. Although complete adsorption occurs, there are still vacancies, resulting in a decrease in the adsorption capacity and an increase in the adsorption rate. It can be found that the amount of FGS is 0.125 mg, which can not only ensure complete adsorption but also reduce the waste of the adsorbent. Therefore, the optimal dosage of the adsorbent selected for the next test is 0.125 mg. Figure 3 Effect of the dosages of Fe3O4, Fe3O4 / GO, and FGS on the adsorption of Gly.

[0053] ②. Initial concentration of glyphosate: In the range of 200 - 500 mg / L of Gly (C0), the effect of the initial concentration on the adsorption capacity was studied using the optimal amount of 0.125 mg of the adsorbent to eliminate the influence of the adsorbent dosage determined previously, as Figure 2 shown in C. Before the initial Gly concentration reaches 350 mg / L, the adsorption capacity of the FGS adsorbent for Gly increases sharply, which may be related to the adsorption driving force when the initial Gly concentration is high, resulting in an increase in the adsorption capacity. However, the active sites on the surface of the quantitative adsorbent are limited. When the Gly concentration is too high, the adsorption sites on the surface of FGS reach saturation, resulting in the inability of Gly molecules to bind to the adsorption sites. The adsorption capacity no longer increases but shows a stable trend. While keeping the above concentration gradient unchanged, the adsorption capacity of Fe3O4 for Gly still increases slowly after 350 mg / L, and the adsorption of FG for Gly begins to reach equilibrium at 450 mg / L. Given that Fe3O4 and FG are only used as reference objects for the experiment, the optimal initial concentration value of 350 mg / L was selected for the subsequent batch experiments.

[0054] ③. pH value of the solution: The pH value of the solution directly affects the surface charge properties of FGS and the molecular form of Gly in aqueous solution. Gly is an amphiphilic molecule containing an amino group and a phosphonic acid group, which will dissociate to varying degrees in the pH range of 2 to 12, resulting in its valence changing from a single positive charge of the amino group to a triple negative charge of the phosphonic acid group. The acid dissociation equilibrium constant is as Figure 4 shown. The various pH values of the Gly solution were adjusted from 2 to 12 using HCl and NaOH while keeping the initial concentration and material dosage constant (C0 = 350 mg / L, m = 0.125 mg). The adsorption results of Fe3O4, FG, and FGS are as Figure 2 shown in D.

[0055] The adsorption capacity of FGS increases as the pH value increases from 1 to 3 and reaches the maximum adsorption capacity at pH = 3. After the pH value exceeds 3, the adsorption capacity continues to decline. As Figure 5 shown, the pH of FGS pzc is 6.84. When the solution is in extremely acidic conditions (pH < 3), FGS is positively charged due to surface protonation, and Gly exists in the form of positive ions (Gly + ), resulting in electrostatic repulsion between the already adsorbed Gly and reducing the adsorption capacity. In the weakly acidic medium of pH 3 - 6, the surface charge of FGS is still positive (pH pzc < 6.84), and due to the two deprotonated hydroxyl groups in the carboxylate and phosphate moieties, Gly shows a negative charge (Gly - ), which produces electrostatic attraction with FGS and enhances the adsorption ability. As the solution turns alkaline (pH > 7), the surface ζ potential of FGS turns negative (pH pzc > 6.84), and the negative charge of glyphosate increases, resulting in electrostatic repulsion with FGS and a decrease in the adsorption amount. In addition, OH- in the alkaline environment competes with Gly for the available sites on the FGS surface, which is not conducive to adsorption. Therefore, pH = 3 is selected as the fixed parameter for the next experiment.

[0056] ④. Contact time: The contact time (t) between the adsorbent and the adsorbate is a key parameter for evaluating the adsorption process. Figure 2 Figure E shows the effect of contact time in the range of 10 - 200 min on the adsorption capacity of three adsorbents for Gly, while keeping the optimized parameters constant (m = 0.125 mg, pH = 3, C0 = 350 mg / L, and 25 °C). The adsorption capacity of FGS increases significantly within 40 min, then increases slowly after 40 min, and finally reaches the adsorption equilibrium at 90 min. At the beginning of 40 min, due to a large number of active sites on the FGS surface, Gly is likely to be adsorbed rapidly. As the adsorption reaction proceeds, the active sites on the FGS surface are gradually occupied by Gly. Therefore, Gly is adsorbed slowly until the adsorption equilibrium is reached. Fe3O4 and FG reach equilibrium at 50 min and 120 min respectively as reference groups.

[0057] 3. Coexisting ion competition experiment: Generally, agricultural wastewater related to glyphosate pollution contains different anions, such as chlorides, nitrates, and phosphates produced by the application of nitrogen and phosphorus fertilizers. Select Cl - , PO4 3- , and NO3 - as three typical anions as coexisting ions, and add different concentrations (Cl- , PO4 3- and NO3 - were 0.1, 0.15, and 0.2 mol / L, respectively) for exploration. From Figure 2 F, it can be seen that PO4 3- and NO3 - had a negative impact on the adsorption of Gly on FGS, but Cl - had almost no effect. This can be explained as the charge and chemical function of PO4 3- being similar to the phosphate group in Gly, resulting in competitive adsorption effects and reduced adsorption capacity of Gly.

[0058] 4. Regenerability of the FGS adsorbent: The regenerability of the FGS adsorbent plays an important role in practical applications. The cyclic batch experiments of FGS for Gly were explored, and the results are as Figure 6 shown. It can be observed that after 4 cycles of using the same batch of FGS adsorbent, the adsorption capacity of Gly decreased from 89.41 mg / g to 65.72 mg / g. The slight decrease in adsorption capacity during consecutive cycles may be due to incomplete desorption of Gly, loss of adsorption sites, or mass loss of FGS during the desorption process, or changes in the chemical composition and morphology of FGS. The above analysis results indicate that FGS has good reusability and is expected to capture Gly from actual wastewater.

[0059] 5. Adsorption isotherm performance parameters: To analyze the interaction between the adsorbent and the adsorbate and the quantitative study of the maximum saturated adsorption capacity at equilibrium, the adsorption experiments of Fe3O4, FG, and FGS for Gly at different concentrations (50 - 1000 mg / L) were analyzed using the Langmuir and Freundlich isothermal adsorption models. The fitting curves and corresponding parameters are as Figure 7 (m = 2.5 g / L, C0 = 350 mg / L, pH = 3.2, t = 70 min) and Figure 8 shown. The Langmuir model showed a higher degree of fit, and the R 2 values of Fe3O4, FG, and FGS were 0.907, 0.884, and 0.959, respectively, while the R 2 values of the Freundlich model were 0.836, 0.852, and 0.891, indicating that Gly molecules occupied the active sites with uniform energy on the 3 composite adsorbents through monolayer adsorption. In addition, the 1 / n values of the Freundlich adsorption isotherm model for Gly of the 3 adsorbents were all in the range of 0 - 1, so all adsorbents showed a high adsorption affinity for Gly. The theoretical maximum adsorption capacities (Q m)The values are 80.24 mg / g, 47.91 mg / g, and 101.1 mg / g respectively. Compared with other reported adsorbents (see Figure 9 ), the maximum saturated adsorption capacity (q max ) of FGS is significantly comparable, indicating that it can effectively capture Gly from wastewater.

[0060] The above embodiments only exemplarily illustrate the principles and effects of the present invention, rather than limiting the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A rare earth Sm-based composite nanomaterial for capturing glyphosate in a water environment, characterized in that: The method comprises the following preparation steps: S1: synthesis of Fe3O4 by coprecipitation; S2: Preparation of Fe3O4 and GO composite material Fe3O4 / GO; S3: Fe3O4 / GO / Sm(OH)CO3 was prepared by slightly modified chemical homogeneous precipitation using urea.

2. The rare earth Sm-based composite nanomaterial for capturing glyphosate in a water environment according to claim 1, characterized in that: When synthesizing Fe3O4, 0.556 g FeSO4·7H2O and 1.082 g FeCl3·6H2O were added to 40 mL distilled water, and then 3 mL ammonia was injected into the mixed solution to adjust the pH to 11. The resulting solution was stirred at 40 °C for 20 min. The final nano-Fe3O4 product was collected by magnet assistance and washed with deionized water, then dried at 60 °C and ground before use.

3. The rare earth Sm-based composite nanomaterial for capturing glyphosate in water environment according to claim 2, characterized in that: When preparing Fe3O4 / GO, 20 mg of GO was ultrasonically dispersed in 25 mL of distilled water for 30 min, and 0.1 g of the nano-Fe3O4 prepared above was added. Thereafter, the entire mixture was transferred to a three-necked flask under mechanical stirring at 60 °C for 1 h. The solid nanocomposite Fe3O4 / GO was separated using an external magnet, washed with deionized water until neutral, and dried at 60 °C for 12 h.

4. The rare earth Sm-based composite nanomaterial for capturing glyphosate in water environment according to claim 3, characterized in that: When preparing Fe3O4 / GO / Sm(OH)CO3, 50 mg Fe3O4 / GO was dispersed in 200 mL distilled water under ultrasonic treatment, and then 1.5 g urea was added. After 10 min, Sm(NO3)3·6H2O was added and kept in an ultrasonic water bath. The pH value of the mixed solution was adjusted to 5 with a small amount of ammonia water. The reaction was carried out at 90 °C for 2 h. The final precipitate was washed several times with distilled water and anhydrous ethanol, respectively, and dried at 60 °C overnight.

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