Preparation method of iron-lanthanum modified biochar and application of iron-lanthanum modified biochar in adsorption antimony removal

Abstract

The invention discloses a one-step hydrothermal preparation method of iron-lanthanum modified biochar with municipal sludge as a precursor and application of the iron-lanthanum modified biochar in efficient removal of Sb (V) in printing and dyeing wastewater. FeSO4. 7H2O, FeCl3 and La (NO3) 3.6 H2O are prepared into a modifier solution, municipal sludge powder is directly added, a hydrothermal reaction is performed for 12 h under the conditions that the pH is 10-11 and the temperature is 200 DEG C, and the iron-lanthanum modified biochar is obtained through washing, drying and grinding. SEM (scanning electron microscope) and FTIR (Fourier transform infrared spectroscopy) prove that Fe3O4 and La (OH) 3 are successfully loaded on the surface of the material, and functional groups such as hydroxyl and carboxyl are rich. 0.3 g / L of the modified charcoal is added into 1 mg / L of Sb (V), and the removal rate is gt when the temperature is 25 DEG C and the pH value is 3-6; the adsorption rate is 95%, the adsorption equilibrium can be achieved within 100 minutes, and the maximum adsorption capacity is 61.67 mg / g. According to the process, the municipal sludge serves as the only carbon source, organic matter carbonization and iron-lanthanum oxide loading are synchronously completed under the mild hydrothermal condition, the process is short, energy consumption is low, the cost is controllable, and an efficient, economical and feasible scheme is provided for deep purification of antimony-containing wastewater in the printing and dyeing industry.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary technical field of environmental functional materials and advanced treatment of dyeing and printing wastewater. Specifically, it relates to a biochar prepared by iron-lanthanum co-modification using municipal sludge as a precursor and its application in the removal of antimony (Sb) from dyeing and printing wastewater. Background Technology

[0002] Antimony (Sb) is a typical toxic and harmful heavy metal element, exhibiting chronic toxicity and potential carcinogenicity in humans and animals. In the textile printing and dyeing industry, antimony is mainly used as a catalyst, flame retardant, or dyeing agent in polyester production. These antimony-containing substances gradually migrate and are released during different processes in weaving and printing, ultimately appearing in comprehensive printing and dyeing wastewater at concentrations ranging from hundreds to thousands of micrograms per liter. In comprehensive printing and dyeing wastewater, antimony mainly exists as pentavalent antimony Sb(OH)6. - The antimony exists in various forms. Traditional textile dyeing wastewater treatment processes lack specific technologies for treating antimony. Furthermore, as my country is the world's largest textile producer, large quantities of antimony-containing wastewater are discharged into the natural environment. The revised "Emission Standard of Water Pollutants for Textile Dyeing and Finishing" (GB4287-2012) stipulates a direct and indirect emission limit of 0.10 mg / L for antimony, and even the Jiangsu Provincial Local Standard (DB32 / 3432-2018) specifies a limit of 0.05 mg / L for antimony emissions from textile dyeing wastewater in the Taihu Lake region. Therefore, strengthening the treatment of antimony pollution in textile dyeing wastewater is urgently needed.

[0003] In recent years, biochar adsorption has been considered a promising advanced treatment technology. However, raw biochar has a weak affinity for anionic Sb(V) and low adsorption capacity. Existing metal-loaded modification methods mostly use agricultural and forestry waste as carbon sources, and these methods are energy-intensive, lengthy, and costly, failing to address the complex water quality of dyeing and printing wastewater and the need for sludge resource utilization. Therefore, developing a novel functional material that is simple to process, low in cost, and can simultaneously and efficiently remove antimony from dyeing and printing wastewater in a single process has become a key technological bottleneck that urgently needs to be addressed for the green upgrading of the dyeing and printing industry. Summary of the Invention

[0004] To address the problems of weak affinity and low adsorption capacity of existing biochar for anionic Sb(V), as well as the high cost of existing biochar preparation, this invention aims to solve the problem of treating low-concentration antimony-containing wastewater discharged from the dyeing and printing industry. It proposes an iron-lanthanum modified biochar synthesized in one step using municipal sludge as raw material. By simultaneously introducing Fe and La dual active centers to enhance the complexation-electrostatic synergistic adsorption of Sb(V), it achieves efficient, low-cost, and resource-based removal of antimony from dyeing and printing wastewater.

[0005] The first aspect of this invention provides a method for preparing iron-lanthanum modified biochar, the method comprising the following steps: (1) Dissolve FeSO4·7H2O, FeCl3 and La(NO3)3·6H2O in deionized water to prepare a modifier mixture A. Then add municipal sludge powder to obtain a mixed solution B. Then add sodium hydroxide solution dropwise to mixed solution B until the pH is 9~12. Stir continuously for 1~6 h to obtain mixed solution C. (2) Transfer the mixed solution C from step (1) to a polytetrafluoroethylene-lined reactor. Place the reactor in an oven and heat it to 180~200 ℃ for 6~12 h. Then remove the reactor and cool it to room temperature. Filter the mixed solution in the reactor and wash it with deionized water 3~6 times. Place it in an oven and dry it to constant weight. Grind it through a 200-mesh sieve to obtain iron-lanthanum modified biochar.

[0006] This invention directly uses municipal sludge as the carbon source for preparing biochar, resulting in low raw material costs and realizing the resource utilization of municipal sludge. Municipal sludge contains a large amount of organic carbon source, and hydrothermal carbonization can obtain porous biochar. The iron-lanthanum modified biochar obtained by in-situ hydrothermal carbonization of iron and lanthanum salts in this invention has good adsorption performance.

[0007] Furthermore, in step (1) above, the molar ratio of FeSO4·7H2O and FeCl3 is 1~2:1~2; further, it is 1~2:1, and the optimal ratio is 1:2.

[0008] Furthermore, the total molar concentration of iron and lanthanum in the modifier mixture A in step (1) above is 0.1~0.4 mol / L. Actual research has shown that different concentrations of modifiers and the ratio of different types of modifiers used have a significant impact on the adsorption performance of modified biochar.

[0009] Furthermore, in step (1) above, the molar ratio of iron to lanthanum in the mixed solution A is 1~2:1~2; further, it is 1~2:1, and the optimal ratio is 1:2. The present invention found that when the ratio of iron to lanthanum is 1:2, 1:1, or 2:1, and the total molar concentration of iron and lanthanum is 0.2~0.4 mol / L, the biochar prepared has good adsorption performance for antimony. In particular, when the total molar concentration of iron and lanthanum is 0.3~0.4 mol / L and the molar ratio of iron to lanthanum is 1:2, the modified biochar has the best adsorption performance for antimony.

[0010] Furthermore, in step (1), the pH of the mixed solution B needs to be adjusted to 10-11; the stirring time is 6 h.

[0011] Furthermore, in step (2), the reaction temperature is 200 ℃ and the reaction time is 12 h. A second aspect of the present invention provides an iron-lanthanum modified biochar, which is obtained by the above preparation method.

[0012] Furthermore, the iron-lanthanum modified biochar is loaded with Fe3O4 and La(OH)3.

[0013] The third invention provides a use of iron-lanthanum modified biochar for the treatment of antimony-containing wastewater, specifically, iron-lanthanum modified biochar is used as an adsorbent to remove antimony from wastewater.

[0014] Furthermore, the aforementioned wastewater is dyeing and printing wastewater.

[0015] The beneficial technical effects obtained by this invention are as follows: This invention is the first to propose a one-step synthesis of iron-lanthanum modified biochar using municipal sludge as raw material. By simultaneously introducing Fe and La dual active centers to enhance the complexation-electrostatic synergistic adsorption of Sb(V), the prepared modified biochar exhibits superior antimony adsorption performance and has good commercial value.

[0016] This invention uses municipal sewage sludge as raw material to prepare biochar, thereby making resource-efficient use of municipal sewage sludge and obtaining commercially valuable biochar.

[0017] This invention also compared the adsorption performance of biochar prepared using municipal sludge and other biomass as raw materials and the same method, and found that the modified biochar prepared using municipal sludge as raw material has better adsorption performance. Attached Figure Description

[0018] Figure 1 This is a comparison chart of the adsorption effects of different samples on Sb(V) in Example 1; Figure 2 The graph shows the antimony removal effect of biochar prepared from different biomass raw materials in Example 2. Figure 3 This is a SEM comparison image of SBC and 4-Fe:La(1:2)-SBC in Example 3; Figure 4 Fourier transform infrared spectra of SBC and 4-Fe:La(1:2)-SBC in Example 3; Figure 5 The effect of 4-Fe:La(1:2)-SBC dosage on Sb(V) removal rate in Example 4; Figure 6 The effect of initial pH value on Sb(V) removal rate in Example 5; Figure 7 The adsorption kinetics curves and fitting parameters of 4-Fe:La(1:2)-SBC in Example 6 are shown. Figure 8The adsorption isotherm curves and fitting parameters of 4-Fe:La(1:2)-SBC in Example 7 are shown. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and experimental data tables. Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It should be understood that the following description is merely illustrative and not intended to limit the invention.

[0020] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0021] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including the ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0022] In some instances, approximate terms may correspond to the precision of the instrument used to measure the value. In this specification and claims, scope definitions may be combined and / or interchanged. Unless otherwise stated, these scopes include all subscopes contained therein.

[0023] The indefinite articles “a” and “an” preceding an element or component of this invention do not impose any limitation on the quantity (i.e., number of times) of the element or component. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0024] The terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., used in this invention refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms are not necessarily directed at the same embodiment or example. Furthermore, the technical features involved in the various embodiments of the invention can be combined with each other as long as they do not conflict with each other.

[0025] Unless otherwise specified, the raw materials and equipment used in this invention can be purchased from the market or are commonly used in the field. The methods in the embodiments, unless otherwise specified, are conventional methods in the field. The above are all preferred embodiments of this invention and are not intended to limit the scope of protection of this invention. Therefore, all equivalent changes made to the structure, shape, and principle of this invention should be covered within the scope of protection of this invention.

[0026] An embodiment of the present invention provides a method for preparing iron-lanthanum modified biochar, the method comprising the following steps: Step (1): Dissolve FeSO4·7H2O, FeCl3 and La(NO3)3·6H2O in deionized water to prepare a modifier mixture A. Then add municipal sludge powder to obtain a mixed solution B. Next, add sodium hydroxide solution dropwise to mixed solution B until the pH is 9~12. Continue stirring for 1~6 h to obtain mixed solution C. Step (2): Transfer the mixed solution C from step (1) to a polytetrafluoroethylene-lined reactor. Place the reactor in an oven and heat it to 180-200℃ for 6-12 h. Then remove the reactor and cool it to room temperature. Filter the mixed solution in the reactor and wash it with deionized water 3-6 times. Place it in an oven and dry it to constant weight. Grind it through a 200-mesh sieve to obtain iron-lanthanum modified biochar.

[0027] In some embodiments, the molar ratio of FeSO4·7H2O and FeCl3 in step (1) is 1~2:1~2; further, it is 1~2:1, and most preferably 1:2.

[0028] In some embodiments, the total molar concentration of iron and lanthanum in the modifier mixture A in step (1) is 0.1~0.4 mol / L, specifically 0.1 mol / L, 0.2 mol / L, 0.3 mol / L or 0.4 mol / L.

[0029] In some embodiments, the molar ratio of iron to lanthanum in the mixed solution A in step (1) is 1~2:1~2, more preferably 1~2:1, and most preferably 1:2.

[0030] In some embodiments, the total molar concentration of iron and lanthanum in the mixed solution A in step (1) is 0.3~0.4 mol / L, and the molar ratio of iron to lanthanum is 1:2.

[0031] In some embodiments, the pH of the mixed solution B in step (1) needs to be adjusted to 10-11; the stirring time is 6 h.

[0032] In some embodiments, the reaction temperature in step (2) is 200 °C and the reaction time is 12 h.

[0033] The present invention provides an iron-lanthanum modified biochar supported on Fe3O4 and La(OH)3.

[0034] The present invention provides an iron-lanthanum modified biochar for the treatment of antimony-containing wastewater. When the modified biochar is added at 0.3 g / L to 1 mg / L Sb(V), the removal rate is >95% at 25 ℃ and pH 3~6. It can reach adsorption equilibrium in 100 min and the maximum adsorption capacity is 61.67 mg / g.

[0035] Example 1 Different amounts of FeSO4·7H2O, FeCl3, and La(NO3)3·6H2O were dissolved in 20 mL of deionized water. Then, 0.2 g of municipal sludge powder was added, followed by the addition of sodium hydroxide solution until the pH reached 10-11. The mixture was stirred for 2 h. The stirred solution was then transferred to a polytetrafluoroethylene-lined reactor, which was placed in an oven and heated to 200 °C for 12 h. The reactor was then removed and cooled to room temperature. The mixed solution in the reactor was filtered and washed 3-6 times with deionized water. It was then dried in an oven to constant weight and ground through a 200-mesh sieve to obtain a series of iron-lanthanum modified biochars, which were named x-Fe:La(a:b)-SBC. The total iron-lanthanum loadings of 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, and 0.4 mol / L were represented by x=1, x=2, x=3, and x=4, respectively, and a:b represented the iron-lanthanum loading ratio.

[0036] Each of the obtained lanthanum iron-modified biochar samples (0.015 g) was added to an iodine flask containing 50 mL of 1 mg / L Sb(V) solution. The iodine flask was then shaken in a constant temperature air bath at 25 °C and 180 rpm for 12 h. The shaken solution was then filtered through a 0.45 μm filter for quantitative analysis. The concentration of Sb(V) in the supernatant was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES) to calculate the removal efficiency. The results are shown in the attached figure. Figure 1 As shown, the removal rate of Sb(V) by the unmodified biochar SBC was only 0.44%. (The text abruptly ends here, likely due to an incomplete translation or missing information.) Figure 1It can be seen that although the removal rate of Sb(V) by iron-modified biochar is improved compared with that of SBC, the overall removal effect is poor. This may be because the amount of iron that can be loaded by the one-step hydrothermal method is limited, which cannot provide sufficient active sites. Lanthanum-modified biochar and iron-lanthanum-modified biochar have good removal effects on Sb(V), and the removal rate increases with the increase of loading. Among them, 4-Fe:La(1:2)-SBC has the best removal effect on Sb(V), and its removal rate of Sb(V) can reach 96.98%.

[0037] Example 2 Based on Example 1, the difference is that the biomass used is replaced by corn stalks instead of municipal sludge, and corn stalk biochar (CBC) and iron-lanthanum modified corn stalk biochar (4-Fe:La(1:2)-CBC) are prepared.

[0038] The biochar adsorption effect test was the same as in Example 1. The results are as follows: Figure 2 As shown, both municipal sludge biochar and corn stalk biochar exhibited weak antimony adsorption capacity. After modification with iron and lanthanum, the adsorption performance of both biochars improved, but the antimony removal effect of iron-lanthanum modified municipal sludge biochar was significantly better than that of iron-lanthanum modified corn stalk biochar. This difference may be related to the characteristics of the raw materials themselves and the hydrothermal temperature. At 200 ℃, the abundant inorganic components and organic matter in municipal sludge more easily form a stable and well-developed pore structure, providing an ideal carrier for the uniform loading of iron and lanthanum oxides, thereby enhancing the adsorption activity for antimony. In contrast, corn stalks are mainly composed of cellulose, which is difficult to fully transform into carbon materials with high specific surface area and stable structure under hydrothermal conditions at 200 ℃. This may lead to insufficient exposure of active sites and poor metal loading, thus limiting its final antimony adsorption performance.

[0039] Example 3 The prepared SBC and 4-Fe:La(1:2)-SBC samples were analyzed and characterized from multiple perspectives. To further elucidate the structural evolution at the microscopic level of the sludge biochar SBC and iron-lanthanum modified biochar 4-Fe:La(1:2)-SBC described in this invention, both were systematically characterized using SEM, and the results are shown in the appendix. Figure 3 As shown in the figure, SBC is mainly composed of overlapping micron-sized sheet-like networks with abundant attachment sites on its surface, and some micropores are generated during the overlapping process. In contrast, the surface of 4-Fe:La(1:2)-SBC loaded with iron and lanthanum shows the attachment of many nano-Fe3O4 particles, which significantly increases the specific surface area of ​​biochar. At the same time, a large number of nanorods are observed growing at the edges of the sheets and at the pore openings, which are speculated to be La(OH)3, proving the successful loading of Fe3O4 and La(OH)3.

[0040] Further FTIR characterization of the surface functional groups of SBC and 4-Fe:La(1:2)-SBC is shown in the attached figure. Figure 4 As shown, at 3420 cm -1 The prominent broad absorption peaks in the vicinity indicate the presence of stretching vibrations of hydroxyl groups (-OH), suggesting that hydroxyl groups are distributed on the material surface or in the interlayer region. (2681-2934 cm⁻¹) -1 The absorption peaks in the range indicate CH bonds. (1604 cm⁻¹) -1 and 1297-1430 cm -1 The absorption peaks in the intervals represent -COO - The symmetric and asymmetric stretching vibrations confirmed the widespread presence of carboxyl groups (-COOH) in the material. 1110 cm⁻¹ -1 The vibration mode at this location may be related to CO stretching vibration. 776 cm -1 The peak at 617 cm⁻¹ represents Fe-O. This is likely due to the small amount of Fe present in SBC itself, which explains the minimal change in peak value after modification. In contrast, 4-Fe:La(1:2)-SBC shows a peak at 617 cm⁻¹. -1 The emergence of new absorption peaks is attributed to the La-O vibration. FTIR analysis not only confirms the successful loading of La and Fe, but also demonstrates that the biochar surface is rich in functional groups, providing abundant adsorption sites for Sb(V).

[0041] Example 4 This study investigated the effect of dosage on the adsorption of Sb(V) by iron-lanthanum modified biochar. 50 mL of 1 mg / L Sb(V) solution was added to an iodine flask. Then, 0.005, 0.010, 0.015, 0.020, and 0.025 g (corresponding to adsorbent concentrations of 0.1–0.5 g / L) of 4-Fe:La(1:2)-SBC prepared in Example 1 were added to the iodine flask, respectively. The shaking conditions, time, Sb(V) concentration detection, and removal rate calculation methods were all consistent with those in Example 1. The results are attached. Figure 5 As shown, the removal rate of Sb(V) significantly increased with increasing dosage. When the dosage of 4-Fe:La(1:2)-SBC increased from 0.1 g / L to 0.2 g / L, the Sb(V) removal rate rose from 42.15% to 91.6%; further increasing the dosage to 0.3 g / L, the removal rate further increased to 99.08%, resulting in a residual Sb(V) concentration in the wastewater far below the 0.1 mg / L limit stipulated in the "Water Pollutant Discharge Standard for Textile Dyeing and Finishing Industry" (GB4287-2012). Further increasing the dosage stabilized the removal rate at over 99%.

[0042] Example 5 This study investigated the effect of initial pH on the adsorption of Sb(V) by iron-lanthanum modified biochar. Specifically, 200 mL of a 1 mg / L Sb(V) solution was measured into a beaker, and the pH was adjusted to 3–11 using 1 mol / L NaOH / HCl solution. Then, 50 mL of the solution was transferred to an iodine flask, and 0.015 g of 4-Fe:La(1:2)-SBC was added. The shaking conditions, time, Sb(V) concentration, and removal rate calculations were consistent with those in Example 1. The results are attached. Figure 6 As shown, within the pH range of 3–6, the removal rate of Sb(V) by 4-Fe:La(1:2)-SBC remained above 90%. At pH 7–8, the removal rate decreased slightly to around 80%. With further increases in pH, the removal rate decreased sharply, even dropping to only about 10% at pH 11. This may be because the functional groups on the material surface are fully protonated under acidic conditions, allowing for the removal of Sb(OH)6. - Sb(V) in its existing form exhibits strong electrostatic attraction and coordination complexation; however, under alkaline conditions, deprotonation occurs on the material surface, resulting in negatively charged Sb(OH)6. - Electrostatic repulsion occurs, which is detrimental to the adsorption process and leads to a decrease in removal rate.

[0043] Example 6 0.15 g of 4-Fe:La(1:2)-SBC prepared in Example 1 was added to 500 mL of a 1 mg / L Sb(V) solution and stirred mechanically in a water bath at 25 °C and 180 rpm. Samples were taken at 1, 3, 5, 7, 10, 15, 20, 30, 40, 50, 60, 80, 100, 120, 150, 180, 210, 240, 270, 300, 360, 420, and 480 min. The samples were then filtered through a 0.45 μm filter membrane. The concentration of Sb(V) in the supernatant was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), and the results were fitted using pseudo-first-order and pseudo-second-order kinetic models. The results are shown in Table 1 and Appendix. Figure 7 As shown.

[0044] Table 1 Fitting parameters of pseudo-first-order and pseudo-second-order kinetic models for adsorption kinetics Table 1 shows that the correlation coefficient of the quasi-second-order dynamics model fit is ( R The value of ² = 0.9177 is significantly higher than that of the pseudo-first-order dynamic model ( RThe value of ² = 0.8155 indicates that the adsorption behavior is more consistent with the pseudo-second-order kinetic model, suggesting that the adsorption mechanism is mainly chemisorption. Further analysis of the adsorption kinetics revealed that the adsorption of Sb(V) by 4-Fe:La(1:2)-SBC exhibits a distinct two-stage characteristic: the adsorption rate is relatively fast in the initial 0–80 min, completing approximately 90% of the total adsorption capacity; subsequently, a slow adsorption stage occurs from 80–480 min, gradually approaching equilibrium. This behavior can be attributed to the abundance of active adsorption sites on the material surface in the initial stage, allowing for rapid adsorption of Sb(OH)₆. - As adsorption proceeds, the number of remaining available sites decreases, leading to a decline in the adsorption rate. In summary, the adsorption of Sb(V) by 4-Fe:La(1:2)-SBC is a nonlinear process dominated by chemisorption.

[0045] Example 7 0.015 g of 4-Fe:La(1:2)-SBC prepared in Example 1 was added to a series of Sb(V) solutions containing concentrations of 0.5, 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 60, 80, 100, and 120 mg / L. The shaking conditions, time, Sb(V) concentration detection, and removal rate calculation were consistent with those in Example 1. The data were fitted using the Langmuir and Freundlich equations, and the results are shown in Table 2 and Appendix. Figure 8 As shown.

[0046] Table 2 Fitting parameters of Langmuir and Freundlich isotherms adsorption models Table 2 shows that as the initial concentration of Sb(V) increases, the adsorption capacity of the material increases accordingly and gradually reaches saturation, indicating that the active sites on the adsorbent surface are gradually occupied. The maximum adsorption capacity obtained by fitting the Langmuir model ( q m The value was 61.67 mg / g, and its correlation coefficient was ( R 2 = 0.9888) is higher than the Freundlich model ( R 2 = 0.9693), indicating that the adsorption process is more consistent with the monolayer adsorption mechanism. In the Freundlich model fitting parameters, 1 / n A value of 2.398 (between 0 and 1) indicates that adsorption is readily achieved and that the adsorption is mainly chemisorption, consistent with the kinetic conclusions of Example 5. A higher value indicates... K F The value (8.422) reflects a strong affinity between the adsorbent and Sb(V). Furthermore, in the Langmuir model...K L The value was 0.098 L / mg, which is within the range of 0 to 1, further confirming that 4-Fe:La(1:2)-SBC has good adsorption capacity and selectivity for Sb(V).

[0047] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing iron-lanthanum modified biochar, characterized in that, The preparation method includes the following steps: Step (1): Dissolve FeSO4·7H2O, FeCl3 and La(NO3)3·6H2O in deionized water to prepare a modifier mixture A. Then add municipal sludge powder to obtain a mixed solution B. Next, add sodium hydroxide solution dropwise to mixed solution B until the pH is 10~12. Continue stirring for 1-6 h to obtain mixed solution C. Step (2): Transfer the mixed solution C from step (1) to a polytetrafluoroethylene-lined reactor. Place the reactor in an oven and heat it to 180-200℃ for 6-12 h. Then remove the reactor and cool it to room temperature. Filter the mixed solution in the reactor and wash it with deionized water 3-6 times. Place it in an oven and dry it to constant weight. Grind it through a 200-mesh sieve to obtain iron-lanthanum modified biochar.

2. The method for preparing iron-lanthanum modified biochar according to claim 1, characterized in that, In step (1), the molar ratio of FeSO4·7H2O to FeCl3 is 1~2:1~2; further, it is 1~2:1, and the optimal ratio is 1:

2.

3. The method for preparing iron-lanthanum modified biochar according to claim 1, characterized in that, The total molar concentration of iron and lanthanum in the modifier mixture A in step (1) is 0.1~0.4 mol / L.

4. A method for preparing iron-lanthanum modified biochar according to any one of claims 1-3, characterized in that, In step (1), the molar ratio of iron to lanthanum in the mixed solution A is 1~2:1~2.

5. A method for preparing iron-lanthanum modified biochar according to any one of claims 1-3, characterized in that, In step (1), the total molar concentration of iron and lanthanum in mixed solution A is 0.3~0.4 mol / L, and the molar ratio of iron to lanthanum is 1:

2.

6. A method for preparing iron-lanthanum modified biochar according to any one of claims 1-3, characterized in that, In step (1), the pH of the mixed solution B needs to be adjusted to 10-11; the stirring time is 6 h.

7. A method for preparing iron-lanthanum modified biochar according to any one of claims 1-3, characterized in that, In step (2), the reaction temperature is 200 °C and the reaction time is 12 h.

8. A lanthanum-iron modified biochar, characterized in that, The iron-lanthanum modified biochar is obtained by the preparation method described in any one of claims 1-7.

9. The iron-lanthanum modified biochar according to claim 8, characterized in that, The iron-lanthanum modified biochar is loaded with Fe3O4 and La(OH)3.

10. The use of an iron-lanthanum modified biochar, characterized in that, The intended use is for the treatment of antimony-containing wastewater, and the iron-lanthanum modified biochar is obtained by the preparation method described in any one of claims 1-7 or by any one of claims 8-9.

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