Modified camellia oleifera shell charcoal / sodium alginate composite gel ball as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of modified camellia oleifera shell biochar / sodium alginate composite gel beads, which comprises the following specific steps: calcining camellia oleifera shell powder, naturally cooling, sealing and storing to obtain camellia oleifera shell biochar; the preparation method comprises the following steps: modifying the camellia oleifera shell charcoal with dilute nitric acid, adding the modified camellia oleifera shell charcoal into a sodium alginate solution, uniformly mixing to obtain a mixed solution, dropwise adding the mixed solution into a 0.5-5% calcium chloride solution under a stirring condition, continuously stirring until all gel balls can be precipitated to the bottom of a beaker after dropwise adding, finally cleaning the gel balls, absorbing water on the surfaces by filter paper, and drying to obtain the camellia oleifera shell charcoal. The modified camellia oleifera shell biochar / sodium alginate composite gel ball is prepared. The invention further discloses a modified camellia oleifera shell charcoal / sodium alginate composite gel ball and application thereof, the prepared gel ball is high and stable in Pb (II) removal efficiency, the maximum adsorption capacity can reach 236.4 mg / g, and the removal efficiency reaches 72% or above.

Description

Technical Field

[0001] The invention relates to the technical field of biochar adsorption materials, and in particular to a modified camellia oleifera shell biochar / sodium alginate composite gel ball and a preparation method and application thereof. Background Art

[0002] Biochar has the advantages of developed surface pores, large specific surface area, stable structure, low cost, no secondary pollution and renewable. It is an environmentally friendly material with a wide range of sources. It not only has extremely excellent effects in the treatment of environmental pollution, but can also be combined with other materials. It has a very high use value in various fields. Camellia oleifera shells contain a large amount of lignin and have a special physical structure. They are good raw materials for the production of activated carbon. Camellia oleifera shells can be carbonized and activated to produce activated carbon with high activity and adsorption capacity. However, if it is used directly for industrial wastewater treatment, its adsorption performance is poor.

[0003] Organic / inorganic hybrid materials are materials that combine physical or chemical effects such as embedding and coagulation of organic and inorganic substances. At the microscopic scale, the combination of organic and inorganic components makes the hybrid material have the advantages of both components. Compared with traditional composite materials, the outstanding performance and functional advantages of organic / inorganic hybrid materials have made them widely studied and applied in wastewater treatment. Sodium alginate (SA) is a linear natural polymer polysaccharide with a large number of oxygen-containing functional groups on its molecular chain, such as hydroxyl (-OH) and carboxyl (-COOH), which can chelate with divalent and higher heavy metal cations to form a three-dimensional network structure, commonly known as the "eggshell" structure. This property can be used to adsorb and treat heavy metals and organic dyes in water. Summary of the invention

[0004] In order to overcome the shortcomings of the above prior art, the purpose of the present invention is to provide a method for preparing modified camellia oleifera shell biochar / sodium alginate composite gel balls, in which the camellia oleifera shell biochar is modified and then embedded in sodium alginate, thereby solving the problem of poor adsorption performance of camellia oleifera shell biochar in wastewater.

[0005] Another object of the present invention is to provide a modified camellia oleifera shell biochar / sodium alginate composite gel sphere.

[0006] Another object of the present invention is to provide an application of modified camellia oleifera shell biochar / sodium alginate composite gel balls.

[0007] The purpose of the present invention is achieved through the following technical solutions: A method for preparing modified camellia oleifera shell biochar / sodium alginate composite gel spheres, the specific steps are as follows: (1) calcining the tea husk powder, naturally cooling it, and then sealing and storing it to obtain tea husk biochar; (2) Soaking the camellia oleifera shell biochar in dilute nitric acid for 12 to 48 hours, and finally washing, filtering, drying and sealing to obtain modified camellia oleifera shell biochar; (3) Add the modified camellia oleifera shell biochar to the sodium alginate solution and mix well to obtain a mixed solution. Under stirring, drop the mixed solution into a 0.5-5% calcium chloride solution. After the dropwise addition is completed, continue stirring until all the gel balls can be precipitated to the bottom of the beaker. Finally, wash the gel balls and use filter paper to absorb the surface moisture to prepare modified camellia oleifera shell biochar / sodium alginate composite gel balls.

[0008] Preferably, the mass ratio of the modified camellia oleifera shell biochar to the sodium alginate in the sodium alginate solution is 1:0.5-6.

[0009] More preferably, the mass ratio of the modified camellia oleifera shell biochar to the sodium alginate in the sodium alginate solution is 1:4.

[0010] Preferably, the concentration of the sodium alginate solution is 0.5-4%.

[0011] More preferably, the concentration of the sodium alginate solution is 0.5-2%.

[0012] More preferably, the concentration of the sodium alginate solution is 2%.

[0013] Preferably, the concentration of the calcium chloride solution is 1-4%.

[0014] Preferably, the specific preparation steps of the camellia oleifera shell powder in step (1) include: The oil-tea camellia shells are cleaned to remove dust on the surface, and dried in a blast dryer at 50-75° C. to constant weight to obtain dried oil-tea camellia shells. The dried oil-tea camellia shells are put into a grinder and crushed for 3-5 minutes. After multiple crushings, the dried oil-tea camellia shells are passed through an 80-mesh sieve, and the powder that passes through the sieve is sealed and stored to prepare oil-tea camellia shell powder.

[0015] Preferably, the specific steps of calcining in step (1) include: The tea oil shell powder is placed in a crucible, wrapped with tin foil and covered with a lid, and placed in a muffle furnace. The muffle furnace is heated to 450° C. to 650° C. at a heating rate of 5° C. / min and pyrolyzed for 1 to 3 hours.

[0016] Preferably, the specific steps of step (2) are as follows: soaking the camellia oleifera shell biochar in dilute nitric acid for 12 to 48 hours, washing with deionized water, and then filtering, and finally drying at 50° C. to 80° C. for 20 to 24 hours and then sealing and storing to prepare modified camellia oleifera shell biochar.

[0017] Preferably, the molar mass ratio of the camellia oleifera shell biochar to dilute nitric acid is 5:0.01-0.05.

[0018] More preferably, the concentration of the dilute nitric acid is 1 mol / L.

[0019] Preferably, the stirring speed is 200 r / min to 250 r / min.

[0020] Preferably, the mixed solution is dripped at a speed of 2 drops per second.

[0021] The mass molar ratio of the camellia oleifera shell biochar to dilute nitric acid is 5:0.01-0.05 (g / mol).

[0022] A modified camellia oleifera shell biochar / sodium alginate composite gel ball is prepared by the preparation method of the modified camellia oleifera shell biochar / sodium alginate composite gel ball.

[0023] Application of modified camellia shell biochar / sodium alginate composite gel ball for removing Pb from water 2+ , the specific steps are as follows: Adjustment of Pb content 2+ The pH and temperature of the water body are then adjusted, and the modified camellia oleifera shell biochar / sodium alginate composite gel balls are added and stirred for adsorption for 2 to 6 hours.

[0024] Preferably, the Pb-containing 2+ The pH of the water is adjusted to 3-5, and the Pb-containing 2+ The water temperature is adjusted to 298-318K, and the addition amount of the modified camellia oleifera shell biochar / sodium alginate composite gel sphere is 0.51-1.54 g / L.

[0025] More preferably, the added amount of the modified tea oil shell biochar / sodium alginate composite gel ball is 0.77 g / L.

[0026] The present invention has the following advantages and beneficial effects compared with the prior art: (1) The present invention modifies camellia oleifera shells and uses sodium alginate (CA) as a hydrogel matrix to embed modified camellia oleifera shell biochar (COSBC) to prepare CA / COSBC composite gel balls. The modification with dilute nitric acid can add some holes on the surface of biochar, increase the specific surface area and active sites of biochar, and improve the adsorption capacity of the composite gel balls for heavy metals. The embedding of biochar improves the mechanical and mechanical properties of the gel balls. The support of biochar can enrich the pore structure of the gel balls, which is conducive to the diffusion of heavy metal ions to the adsorption sites of the composite gel balls and thus their removal. The hydrogel matrix can provide a stable skeleton support for the biochar, so that it will not be lost and is easy to recover. The composite gel balls are used to treat heavy metal Pb(II) in water bodies. The abundant oxygen-containing functional groups on the surface of the hydrogel can react with Pb 2+ Ion exchange occurs, thereby further enhancing the adsorption effect. The composite gel ball has a high and stable removal efficiency for Pb(II), with a maximum adsorption capacity of 236.4 mg / g and a removal efficiency of more than 72%.

[0027] (2) The present invention has developed a new method for resource processing of oil-tea camellia shells, which avoids the ecological and environmental problems caused by waste oil-tea camellia shells, solves the problem of poor adsorption effect of biochar, and improves the adsorption of heavy metal Pb in water. 2+ processing capabilities.

[0028] (3) The composite gel ball disclosed in the present invention has good recyclability. After five regeneration tests, the composite gel ball has good recyclability to Pb 2+ The adsorption amount can still reach 92% of the initial adsorption amount.

[0029] (4) The oil-tea camellia shell of the present invention is widely available and inexpensive, and the chemicals used, such as nitric acid, calcium chloride and sodium alginate, are commonly used chemical products. The preparation process and operation of the present invention are simple, the preparation is fast, the production cycle is short, no special chemical equipment is required, and industrial production is easy to achieve. The product is non-toxic and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a physical picture of the modified tea oil shell biochar / sodium alginate composite gel sphere prepared in Example 1.

[0031] Figure 2 This is a scanning electron microscope image of the camellia oleifera shell biochar prepared in Example 1.

[0032] Figure 3 This is a scanning electron microscope image of the modified camellia oleifera shell biochar prepared in Example 1.

[0033] Figure 4 This is the infrared image of the modified camellia oleifera shell biochar prepared in Example 1.

[0034] Figure 5 The CA / COSBC composite gel spheres prepared at different CA / COSBC mass ratios in Examples 1 to 5 are 2+ Adsorption diagram.

[0035] Figure 6 The gel balls in Examples 6 to 10 at different dosages have an effect on Pb 2+ Adsorption diagram.

[0036] Figure 7 The gel balls in Examples 11 to 14 react with Pb in water with different pH values. 2+ Adsorption diagram.

[0037] Figure 8 The Pb content of CA / COSBC gel spheres regenerated five times 2+ Adsorption diagram. DETAILED DESCRIPTION

[0038] The purpose of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the implementation mode of the present invention is not therefore limited to the following embodiments.

[0039] Example 1 (1) Preparation of biochar: Place tea husk powder in a crucible and wrap it with tin foil, cover it with a lid, and finally place it in a muffle furnace. Pyrolyze it at a pyrolysis temperature of 500°C for 2 h. After the muffle furnace is naturally cooled, seal it and store it to obtain tea husk biochar. (2) Modified Camellia oleifera shell biochar: Soak the Camellia oleifera shell biochar in dilute nitric acid for 24 hours, wash until the solution is neutral, filter, dry and seal to obtain modified Camellia oleifera shell biochar; (3) Composite preparation of modified camellia oleifera shell biochar / sodium alginate: according to the mass ratio of biochar to sodium alginate in the sodium alginate solution of 1:6, take the biochar and add it to a 2% sodium alginate solution and stir evenly to obtain a mixed solution; under stirring, drop the mixed solution into a 2% calcium chloride solution, and continue stirring for 30 to 60 minutes after the addition is completed, until all the gel balls can be precipitated to the bottom of the beaker, and finally wash and use filter paper to absorb the surface moisture to prepare modified camellia oleifera shell biochar / sodium alginate composite gel balls (CA / COSBC gel balls).

[0040] Pb in water 2+ The processing method: 0.8 g / L of the CA / COSBC gel spheres prepared above were added to a 150 mL conical flask, and then 50 mL of 500 mg / L Pb 2+The solution was poured into it and finally fixed on a magnetic stirrer for stirring and adsorption for 4 h (400 r / min) at a water temperature of 298 K. After the adsorption was completed, the conical flask was taken out and the upper clear liquid was taken. Its absorbance was measured after diluting it 20 times with low-concentration HNO3 and was 0.4654 L·mol -1 cm -1 .

[0041] Determination of lead ion standard curve: The lead ion concentration gradient was configured as 0 mg / L, 1.0 mg / L, 5.0 mg / L, 10.0 mg / L, and 15.0 mg / L. The absorbance was measured at a wavelength of 283.3 nm as 0 L·mol -1 cm -1 , 0.006L·mol -1 cm -1 、0.0491 L·mol -1 cm -1 、 0.121 L·mol -1 cm -1 , 0.189 L·mol -1 cm -1 , with lead ion concentration as the horizontal axis and absorbance as the vertical axis, the standard curve is established as: Y = 41.9236x + 0 2804, R 2 =0 9993.

[0042] Calculate Pb based on the lead ion standard curve 2+ The concentration is 395.85 mg / L.

[0043] Example 2 The difference between this embodiment and embodiment 1 is that the mass ratio of biochar to sodium alginate in the sodium alginate solution is 1:4.

[0044] Treatment of PB in water 2+ The method was the same as in Example 1, and the absorbance was determined to be 0.4689 L·mol -1 cm -1 The calculated lead ion concentration is 398.85 mg / L.

[0045] Example 3 The difference between this embodiment and embodiment 1 is that the mass ratio of biochar to sodium alginate in the sodium alginate solution is 1:2.

[0046] Treatment of PB in water 2+ The method was the same as in Example 1, and the absorbance was determined to be 0.4755 L·mol -1 cm -1 The calculated lead ion concentration is 404.35 mg / L.

[0047] Experimental Example 4 The difference between this embodiment and embodiment 1 is that the mass ratio of biochar to sodium alginate in the sodium alginate solution is 2:1.

[0048] Treatment of PB in water 2+ The method was the same as in Example 1, and the absorbance was determined to be 0.5251 L·mol -1 cm -1 The calculated lead ion concentration is 445.95 mg / L.

[0049] Experimental Example 5 The difference between this embodiment and embodiment 1 is that the mass ratio of biochar to sodium alginate in the sodium alginate solution is 1:1.

[0050] Treatment of PB in water 2+ The method was the same as in Example 1, and the absorbance was determined to be 0.5502 L·mol -1 cm -1 The calculated lead ion concentration is 466.95 mg / L.

[0051] Example 6 0.51 g / L of CA / COSBC gel spheres prepared in Example 2 were added to a 150 mL conical flask, and then 50 mL of 250 mg / L Pb 2+ The solution was poured into it and finally fixed on a magnetic stirrer for stirring and adsorption for 4 h (400 r / min) at a water temperature of 298 K. After the adsorption was completed, the conical flask was taken out and the upper clear liquid was taken. Its absorbance was measured after diluting it 10 times with low concentration HNO3 and was 0.2449 L·mol -1 cm -1 According to the lead ion standard curve determined earlier, its concentration was calculated to be 105.5 mg / L.

[0052] Example 7 The amount of gel spheres added was 0.77 g / L, and the remaining steps were the same as in Example 6. The absorbance was measured to be 0.2003 L·mol -1 cm -1 , the lead ion concentration was 84.25 mg / L.

[0053] Example 8 The amount of gel spheres added was 1.03 g / L, and the remaining steps were the same as in Example 6. The absorbance was measured to be 0.1870 L·mol -1 cm -1 , the lead ion concentration is 78.675 mg / L.

[0054] Example 9 The amount of gel spheres added was 1.29 g / L, and the remaining steps were the same as in Example 6. The absorbance was measured to be 0.1721 L·mol -1 cm -1 , the lead ion concentration is 72.45 mg / L.

[0055] Example 10 The amount of gel spheres added was 1.54 g / L, and the remaining steps were the same as in Example 6. The absorbance was measured to be 0.1245 L·mol -1 cm -1 The calculated lead ion concentration is 52.225 mg / L.

[0056] Embodiment 11 0.77 g / L of CA / COSBC gel spheres prepared in Example 2 were added to a 150 mL conical flask, and then 50 mL of 250 mg / L Pb 2+ The solution was poured into it and finally fixed on a magnetic stirrer for 4 h (400 r / min) of stirring and adsorption. The water temperature was 298 K. After the adsorption was completed, the conical flask was taken out and the upper clear liquid was taken. The absorbance was measured after diluting it 10 times with low concentration HNO3 and the absorbance was 0.4015 L·mol -1 cm -1 According to the lead ion standard curve determined earlier, its concentration was calculated to be 171.15 mg / L.

[0057] Example 12 The difference from Example 11 is that the pH is 3, and the other steps are the same as Example 11. The absorbance measured is 0.2097 L·mol -1 cm -1 , the lead ion concentration was 87.95 mg / L.

[0058] Embodiment 13 The difference from Example 11 is that the pH is 4 and the absorbance is 0.1860 L·mol -1 cm -1 , the lead ion concentration is 77.975 mg / L.

[0059] Embodiment 14 The difference from Example 11 is that the pH is 5 and the absorbance is 0.1621 L·mol -1 cm -1 , the lead ion concentration is 67.975 mg / L.

[0060] Embodiment 15 This embodiment provides a test method for the recycling performance of CA / COSBC; Add 0.1151 g / L CA / COSBC to 150 mL of 250 mg / L Pb 2+ The solution was stirred and adsorbed on a magnetic stirrer for 2 h (400 r / min). 2+ The pH of the solution was 5 and the temperature was 298 K. After the absorption was completed, the saturated CA / COSBC was placed in 50 mL of 0.1 mol / L HCl solution for oscillation regeneration for 2 h. After washing with distilled water, the surface water was dried with filter paper and then placed in the next round of adsorption cycle. This was repeated five times. The results of the five regeneration experiments are shown in Figure 8 .

[0061] Figure 2 and Figure 3 The scanning electron microscope images of the camellia oleifera shell biochar before and after modification are respectively Figure 2 , 3 It can be seen that the modification of dilute nitric acid can add some holes on the surface of biochar, increase the specific surface area and active sites of biochar, and improve the adsorption capacity of composite gel balls for heavy metals.

[0062] Figure 4 This is the infrared image of the modified camellia shell biochar prepared in Example 1. Figure 4 It can be seen that At 3350cm -1 、2924 cm -1 、1689cm -1 、1387cm -1 and 873 cm -1 There are obvious characteristic peaks at 2860~2924 cm-1, which are the stretching vibration peak of -OH, the stretching vibration peak of CH, the vibration peak of C=O of aromatic ketone, the stretching vibration peak of C—O, and the stretching vibration peak of aromatic C—H. -1 There are three peaks, which are the CH stretching vibration peaks in substituted benzene, at 1027~1387 cm -1 The three peaks that appeared were the stretching vibration peaks of C—O in primary alcohol, secondary alcohol and quaternary alcohol. The infrared spectrum showed that CA / COSBC microgel with excellent adsorption performance was successfully prepared.

[0063] Figure 5 The CA / COSBC gel spheres prepared at different CA / COSBC mass ratios in Examples 1 to 5 have a Pb 2+The adsorption diagram shows that as the COSBC ratio decreases, the Pb(II) removal rate increases, the adsorption amount increases first and then reaches a stable state, and when m COSBC : m SA =1:6, the adsorption capacity decreased slightly, and the removal rate increment decreased slightly. The reason may be that too much COSBC was added, which would block the adsorption sites of SA itself, resulting in a decrease in adsorption capacity. When the COSBC content is too low, the microspheres have a high adsorption capacity, but at this time, due to the poor mechanical strength of the microspheres themselves, they are easily deformed or broken by external forces during the solidification and adsorption process, and the wastewater treatment sludge produced has a high moisture content. Therefore, in order to ensure that the gel ball has a certain mechanical strength and excellent adsorption effect, m COSBC : m SA =1:4 is the optimal ratio for preparing CA / COSBC microspheres.

[0064] Figure 6 The gel balls in Examples 6 to 10 at different dosages have an effect on Pb 2+ The adsorption diagram of Figure 6 It can be seen that the Pb(II) removal rate increases with the increase of microsphere dosage, and the adsorption amount decreases continuously. When it reaches 1.29 g / L, the change is relatively slow. Therefore, the optimal dosage is selected as 0.77 g / L. The reason may be that when the Pb(II) content in the solution remains unchanged, the microsphere dosage is small, the more Pb(II) is wrapped by the unit mass of the adsorbent, and the adsorption sites are effectively utilized and the higher the adsorption amount; the increase in dosage can provide sufficient adsorption sites to combine with Pb(II). Since a certain concentration of Pb(II) can only combine with certain adsorption sites, some adsorption sites on the adsorbent will become invalid, and there is an adsorption and desorption equilibrium in the solution, so the adsorption amount will decrease and the removal rate will increase.

[0065] Figure 7 The gel balls in Examples 11 to 14 react with Pb in water with different pH values. 2+ The adsorption diagram of Figure 7 It can be seen that when pH = 2, the system is highly acidic and there are a lot of H + When Pb(II) forms competitive adsorption, the active sites on the surface of CA / COSBC gel balls will be reduced, thereby inhibiting the binding of CA / COSBC with Pb(II). When the pH value is in the range of 3 to 5, the removal rate and adsorption amount of Pb(II) increase slightly with the increase of the pH value of the system. In the present invention, CA / COSBC adsorbs and removes Pb 2+ The effective pH range is 3~5, which is close to the pH value of lead-contaminated water bodies, so the adsorbent can be used for the treatment of actual water bodies.

[0066] Figure 8The Pb content of CA / COSBC gel spheres regenerated five times 2+ The adsorption diagram of Figure 8 It can be seen that the adsorption capacity of CA / COSBC decreased after each regeneration experiment. After five cycles, the final adsorption capacity was 2161 mg / g. After five cycles, the adsorption rate decreased by 5.31%, 5.57%, 5.76%, 6.40% and 7.30%, respectively. This result shows the good regeneration and reusability of CA / COSBC. The recycling performance of the adsorbent is one of the criteria for measuring whether it is a high-performance and high-quality material, which directly determines the production cost of the adsorbent and its potential for large-scale application.

[0067] The above specific implementation modes are preferred embodiments of the present invention and cannot be used to limit the present invention. Any other changes or other equivalent replacement methods that do not deviate from the technical solution of the present invention are included in the protection scope of the present invention.

Claims

1. A method for preparing modified camellia oleifera shell biochar / sodium alginate composite gel spheres, characterized in that: The specific steps are as follows: (1) calcining the tea husk powder, naturally cooling it, and then sealing and storing it to obtain tea husk biochar; (2) Soaking the camellia oleifera shell biochar in dilute nitric acid for 12 to 48 hours, and finally washing, filtering, drying and sealing to obtain modified camellia oleifera shell biochar; (3) Add the modified camellia oleifera shell biochar to the sodium alginate solution and mix well to obtain a mixed solution. Under stirring, drop the mixed solution into a 0.5-5% calcium chloride solution. After the dropwise addition is completed, continue stirring until all the gel balls can settle to the bottom of the beaker. Finally, wash the gel balls and use filter paper to absorb the surface moisture to prepare modified camellia oleifera shell biochar / sodium alginate composite gel balls.

2. The method for preparing the modified camellia oleifera shell biochar / sodium alginate composite gel sphere according to claim 1, characterized in that: The mass ratio of the modified tea oil shell biochar to the sodium alginate in the sodium alginate solution is 1:0.5-6.

3. The method for preparing the modified camellia oleifera shell biochar / sodium alginate composite gel sphere according to claim 1, characterized in that: The concentration of the sodium alginate solution is 0.5-4%.

4. The method for preparing modified tea oil shell biochar / sodium alginate composite gel sphere according to claim 1, characterized in that: The specific preparation steps of the camellia oleifera shell powder in step (1) include: The oil-tea camellia shells are cleaned to remove dust on the surface, and dried in a blast dryer at 50-75° C. to constant weight to obtain dried oil-tea camellia shells. The dried oil-tea camellia shells are put into a grinder and crushed for 3-5 minutes. After multiple crushings, the dried oil-tea camellia shells are passed through an 80-mesh sieve, and the powder that passes through the sieve is sealed and stored to prepare oil-tea camellia shell powder.

5. The method for preparing modified tea oil shell biochar / sodium alginate composite gel sphere according to claim 1, characterized in that: The specific steps of calcining in step (1) include: The tea oil shell powder is placed in a crucible, wrapped with tin foil and covered with a lid, and placed in a muffle furnace. The muffle furnace is heated to 450° C. to 650° C. at a heating rate of 5° C. / min and pyrolyzed for 1 to 3 hours.

6. The method for preparing modified tea oil shell biochar / sodium alginate composite gel sphere according to claim 1, characterized in that: The specific steps of step (2) are as follows: soaking the camellia oleifera shell biochar in dilute nitric acid for 12 to 48 hours, washing with deionized water, and then filtering, and finally drying at 50° C. to 80° C. for 20 to 24 hours and then sealing and storing to prepare modified camellia oleifera shell biochar.

7. The method for preparing modified tea oil shell biochar / sodium alginate composite gel sphere according to claim 1, characterized in that: The molar mass ratio of the camellia oleifera shell biochar to dilute nitric acid is 5:0.01-0.

05.

8. A modified tea oil shell biochar / sodium alginate composite gel ball, characterized in that: The modified camellia oleifera shell biochar / sodium alginate composite gel sphere is prepared by the preparation method of any one of claims 1 to 7.

9. An application of modified tea oil shell biochar / sodium alginate composite gel ball, characterized in that: Used to remove Pb from water 2+ , the specific steps are as follows: Adjustment of Pb content 2+ The pH and temperature of the water body are then adjusted, and the modified camellia oleifera shell biochar / sodium alginate composite gel balls are added and stirred for adsorption for 2 to 6 hours.

10. The method for preparing modified tea oil shell biochar / sodium alginate composite gel sphere according to claim 9, characterized in that: The Pb-containing 2+ The pH of the water is adjusted to 3-5, and the Pb-containing 2+ The water temperature is adjusted to 298-318K, and the addition amount of the modified camellia oleifera shell biochar / sodium alginate composite gel sphere is 0.51-1.54 g / L.

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