Biochar granular material and method for detecting desorption behavior of adsorbed-state Ca < 2 + >
By preparing calcium and strontium adsorbent biochar granular materials, the problem of difficult detection of calcium ion desorption behavior in biochar adsorbed state has been solved, realizing a low-cost and simple detection method that supports applications in agriculture and the environment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-18
- Publication Date
- 2026-03-10
AI Technical Summary
Existing technologies make it difficult to detect the desorption behavior of adsorbed calcium ions in biochar in a low-cost and convenient manner, which limits its application in agriculture, environment and ecology.
Calcium and strontium adsorbent biochar granules were prepared by shaking and filtering the biochar and combining it with a calcium and strontium mixed chloride solution to prepare Na+ adsorbent and calcium and strontium adsorbent biochar. Subsequently, the biochar was shaken and filtered in FeCl2 solution, and the ion content in the exchange solution was measured to calculate the desorption amount and desorption rate.
This provides a low-cost and easily scalable method that can accurately assess the amount and release dynamics of Ca2+ desorbed by biochar, supporting research and applications in fields such as agricultural calcium nutrition regulation, saline-alkali soil remediation, and passivation and fixation of cationic pollutants.
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Figure CN121623767A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of environmental functional materials and soil chemical analysis technology, specifically relating to a biochar granular material and a method for detecting adsorbed Ca. 2+ Methods of desorption behavior. Background Technology
[0002] Biochar, due to its porous structure, high specific surface area, and abundant surface functional groups, is widely used for the adsorption, removal, or fixation of various cationic pollutants, and can also serve as a slow-release carrier for the supply of plant nutrients. Calcium ions, as an essential secondary element for plants, play a crucial role in soil structure formation, saline-alkali soil improvement, and calcium cycling in ecosystems. However, currently, both scientific research and practical applications have paid little attention to the desorption of calcium ions adsorbed by biochar, including the quantity and temporal dynamics of desorption. The desorption of adsorbed calcium ions is related to a series of issues such as plant calcium nutrient supply, the effectiveness of saline-alkali land management, and calcium ion migration in ecosystems, and therefore deserves attention. Since background calcium ions exist in natural bodies such as soil and water, and are no different from those desorbed by biochar, special methods are needed to determine the quantity and behavior of calcium ions desorbed by biochar. Although stable isotopes of calcium (such as...) are used... 44 Labeling Ca is an ideal technique for biochar sources. 2+ Accurate tracking, but 44 The high cost of Ca-labeled materials and the reliance on expensive instruments such as isotope mass spectrometry for detection limit the widespread application of this method in routine research and large-scale applications.
[0003] Therefore, there is an urgent need to establish a detection method that is cost-effective, easy to operate, and readily applicable to accurately assess the adsorbed Ca content in biochar. 2+ The desorption behavior of [the substance] provides a scientific basis and technical support for its rational application in agriculture, environment and ecology. Summary of the Invention
[0004] In view of the above-mentioned prior art, the present invention discloses a biochar particulate material and a method for detecting adsorbed Ca. 2+ A method for detecting desorption behavior is proposed to address the technical problem of difficulty in detecting the desorption behavior of calcium ions at low cost in existing technologies.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a method for preparing calcium-strontium adsorbent biochar particulate material, which includes the following steps: S1: The biochar was washed with acid, then the washed biochar was added to a sodium chloride solution and shaken. After filtration and washing, Na was obtained. + Adsorbed biochar; S2: Preparation of Ca 2+ and Sr 2+ chloride solution with a molar ratio of 50:1~10, Na + adsorptive biochar is added to the calcium-strontium mixed chloride solution and oscillated, and after filtration, cleaning and drying, a calcium-strontium adsorptive biochar granular material is obtained.
[0006] Based on the above technical solutions, the application can be further improved as follows.
[0007] Further, the particle size of the biochar is 2~5mm; the acid is hydrochloric acid with a concentration of 0.05M; the concentration of the sodium chloride solution is 0.5M; and the solid-liquid ratio of the biochar and the sodium chloride solution is 1g:4mL.
[0008] Further, the concentration of the sodium chloride solution is 0.5M. + The solid-liquid ratio of the adsorptive biochar and the calcium-strontium mixed chloride solution is 1g:4mL.
[0009] Further, the oscillation rate is 150r / min, and the oscillation time is 60min.
[0010] Further, the drying temperature is 30~60℃, and the drying is performed until the water content is 30%.
[0011] The application also discloses a method for measuring the desorption amount of Ca 2+ and Sr 2+ in soil based on the calcium-strontium adsorptive biochar granular material. I. The calcium-strontium adsorptive biochar granular material is added to an FeCl2 solution with a pH of 4 and oscillated, and after filtration, an exchange solution is obtained, and then the content of Ca 2+ and Sr 2+ in the exchange solution is measured. II. The content of Ca 2+ and Sr 2+ in the soil to be measured is measured; the calcium-strontium adsorptive biochar granular material with a mass of W b is placed in a material tank (1), and the soil to be measured with a mass of W s is placed in a soil tank (2), and is placed for 3 days. III. The calcium-strontium adsorptive biochar granular material is taken out and mixed by stirring, and then is placed in the material tank (1) again and is placed for 3 days. IV. Step III is repeated, and then the desorbed soil is taken out and the content of Ca 2+ and Sr 2+ in the soil is measured, and the desorption amount of Ca 2+ from the biochar in the soil C s is calculated according to the following formula: C s=Soil adsorbed Ca 2+ Content × (ca) / (cb) In the formula, c = adsorbed Ca in the soil to be tested 2+ Content / Adsorbed Sr in the soil to be tested 2+ Content; a = soil adsorbed Ca 2+ Content / Soil Adsorbed Sr 2+ Content; b = exchange liquid Ca 2+ Content / Sr in exchange medium 2+ Content; calculate the desorbed Ca from biochar using the following formula. 2+ Quantity C b , C b =C s ×(W s / W b ); Measuring the desorbed Ca in water 2+ The measurement includes the following steps: ① Add calcium and strontium adsorbent biochar granules to a FeCl2 solution at pH=4 and shake. After filtration, the exchange solution is obtained. Then, the Ca content in the exchange solution is measured. 2+ and Sr 2+ content; ② Determine the adsorbed state of Ca in the water body to be tested 2+ and Sr 2+ Content; The mass of W b Calcium and strontium adsorbent biochar granules were placed in a nylon mesh bag, and then the nylon mesh bag was placed in a container with a volume of W. w The sample was placed in the water body to be tested for 3 days. ③ Remove the nylon mesh bag, filter the water to be tested, and determine the Ca content in the filtrate. 2+ and Sr 2+ The content of desorbed Ca from biochar in the water is calculated using the following formula. 2+ Quantity C w , C w =Ca in the filtrate 2+ Content × (ca) / (cb) In the formula, c = adsorbed Ca in the water body to be tested 2+ Content / Adsorbed Sr in the water body to be tested 2+ Content; a = Ca in the filtrate 2+ Content / Sr in filtrate 2+ Content; b = exchange liquid Ca 2+ Content / Sr in exchange medium 2+ Content; calculate the desorbed Ca from biochar using the following formula. 2+ Quantity C b , C b=C w ×(W w / W b ).
[0012] Based on the above technical solution, the present invention can be further improved as follows.
[0013] Furthermore, the concentration of FeCl2 solution in steps I and ① is 1.0M; the ratio of calcium and strontium adsorbent biochar particles to FeCl2 solution is 1g:4mL; Furthermore, in steps I and ①, the oscillation rate is 150 r / min and the oscillation time is 60 min.
[0014] Furthermore, the nylon mesh bag has a pore size of 0.5mm.
[0015] The beneficial effects of this invention are: this invention establishes a universal and reliable analytical detection method, which can quantitatively calculate the Ca desorption from biochar. 2+ The absolute quantity (Cb) and desorption rate (r) of biochar can be used to accurately assess the adsorbed Ca content. 2+ The release dynamics and quantity of biochar in the environment. This method provides a crucial quantitative evaluation tool for the mechanistic study and practical application of biochar in agricultural calcium nutrition regulation, saline-alkali soil remediation, and passivation and fixation of cationic pollutants. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of a soil analysis container, where 1 is a material tank; 2 is a soil tank; 3 is a slide plate 1; and 4 is a slide plate 2. Detailed Implementation
[0017] The soil analysis container structure in the method of this invention, which is filled with calcium and strontium adsorbent biochar granules and the soil to be tested, is as follows: Figure 1 As shown, the volume of the soil analysis container is 100×80×50mm. The interior of the container is divided into a material tank 1 and a soil tank 2 by a removable partition. The soil tank 2 is located on both sides of the material tank 1. The bottom of the soil analysis container is equipped with sliding plates 1 and 2 that can slide back and forth, which are used to open or close the material tank 1 and the soil tank 2.
[0018] The specific embodiments of the present invention will be described in detail below with reference to examples.
[0019] Example 1 Preparation of biochar: Poplar wood is sawn into particles of 3-5 mm in size and placed at 500℃ for high-temperature pyrolysis for 3 hours to obtain biochar. The obtained biochar is washed with 10% hydrochloric acid to remove carbonates. Its basic properties are shown in Table 1 below.
[0020] Soil: The soil was collected from Heishi County, Guizhou Province. The soil type is yellow-brown soil, and the texture is clay loam. Tobacco has been grown there for a long time. The basic properties of the soil are shown in Table 1 below.
[0021] Table 1
[0022] A method for preparing calcium and strontium adsorbent biochar particulate material includes the following steps: S1: Wash the biochar with 0.05M hydrochloric acid to remove carbonates, rinse with water to remove residual hydrochloric acid, and dry at 45℃. Then, take 25g of the dried biochar and place it in a 150mL centrifuge tube, add 100mL of 0.5M NaCl solution, and shake at 150r / min for 60min at room temperature. After filtration, wash the filter residue three times with 0.1M NaCl solution, and then wash three times with water to obtain NaCl. + Adsorbed biochar; S2: Prepare a calcium-strontium mixed chloride solution with a total concentration of 0.1M, wherein Ca... 2+ and Sr 2+ The molar ratio is 50:1; Na is added at a material-to-liquid ratio of 1g:4mL. + The adsorbent biochar was added to a calcium and strontium mixed chloride solution and shaken at 15°C for 60 min at a shaking rate of 150 r / min. The mixed solution was filtered off, and the filter residue was washed three times with 0.1 M NaCl solution, then washed three times with water. Finally, it was dried at 45°C until the moisture content was 30% to obtain calcium and strontium adsorbent biochar granular material.
[0023] A method for measuring desorbed Ca in soil based on calcium and strontium adsorption biochar granular materials 2+ The method of measurement includes the following steps: I. Take 25g of calcium-strontium adsorbent biochar granules and add them to 100mL of 1.0M FeCl2 solution (pH=4.0). Shake at 15℃ for 60min at a shaking rate of 150r / min. Filter to obtain the exchange solution. Test the Ca content in the exchange solution. 2+ and Sr 2+ The content is calculated, and the b value is determined, where b = Ca of the exchange liquid. 2+ Content / Sr in exchange medium 2+ content; II. Determination of adsorbed Ca in the soil to be tested 2+ and Sr 2+ The content was determined, and the c-value was calculated, where c = the adsorbed Ca content in the soil to be tested. 2+ Content / Adsorbed Sr in the soil to be tested 2+ Content; Weigh 200g (dry basis weight W) b400g (dry basis mass W) of calcium and strontium adsorption type biochar granular material was placed in the material tank 1 of the soil desorption container. s The soil to be tested was evenly placed in the soil tanks 2 on both sides of the material tank 1, and compacted tightly to ensure full contact between the soil and the biochar granules. It was then left to stand for 3 days. Ⅲ. Remove slide plate 3, take out the calcium and strontium adsorbent biochar granules and re-stir and mix the biochar granules, then put them back into material tank 1, compact them tightly, so that the soil and biochar granules are in full contact, and let them stand for 3 days. IV. Repeat step III, remove slide 2, then take out the desorbed soil and measure the adsorbed Ca in the soil. 2+ and Sr 2+ Content, and calculate the value of a, where a = soil adsorbed Ca 2+ Content / Soil Adsorbed Sr 2+ The content is then calculated using the following formula to determine the Ca desorption from the biochar. 2+ Quantity C s Biochar desorption of Ca 2+ Quantity C b The desorption rate r was calculated; the results are shown in Table 3.
[0024] C s =Soil adsorbed Ca 2+ Content × (ca) / (cb) C b =C s ×(W s / W b ) r=C b / Ca in the exchange medium 2+ Content × 100% Table 2
[0025] Cs=14.06×(245.45-180.26) / (245.45-112.52)=6.89 C b =6.89×(400 / 200)=13.678 cmol / kg r = 13.78 / 24.53 × 100% = 56.2% Example 2 The preparation method of biochar is the same as in Example 1.
[0026] Soil: The soil was collected from Haidian District, Beijing. The soil type was alluvial soil, and the texture was sandy loam. The basic properties of the soil are shown in Table 3 below.
[0027] Table 3
[0028] A method for preparing calcium and strontium adsorbent biochar particulate material includes the following steps: S1: Wash the carbonates in the biochar with 0.05M hydrochloric acid, rinse with water to remove residual hydrochloric acid, and dry at 50℃. Then, take 20g of the dried biochar and put it into a 150mL centrifuge tube, add 80mL of 0.5M NaCl solution, and shake at 150r / min for 60min at room temperature on a reciprocating shaker. After filtration, wash the filter residue three times with 0.1M NaCl solution, and then wash three times with water to obtain NaCl. + Adsorbed biochar; S2: Prepare a calcium-strontium mixed chloride solution with a total concentration of 0.1M, wherein Ca... 2+ and Sr 2+ The molar ratio is 50:1; Na is added at a material-to-liquid ratio of 1g:4mL. + The adsorbent biochar was added to a calcium and strontium mixed chloride solution and shaken at 15°C for 60 min at a shaking rate of 150 r / min. The mixed solution was filtered off, and the filter residue was washed three times with 0.1 M NaCl solution, then washed three times with water. Finally, it was dried at 30°C until the moisture content was 30% to obtain calcium and strontium adsorbent biochar granular material.
[0029] A method for measuring desorbed Ca in soil based on calcium and strontium adsorption biochar granular materials 2+ The method of measurement includes the following steps: I. Take 20g of calcium-strontium adsorbent biochar granules and add them to 80mL of 1.0M FeCl2 solution (pH=4.0). Shake at 15℃ for 60min at a shaking rate of 150r / min, and filter to obtain the exchange solution. Test the Ca content in the exchange solution. 2+ and Sr 2+ The content is calculated, and the b value is determined, where b = Ca of the exchange liquid. 2+ Content / Sr in exchange medium 2+ content; II. Determination of adsorbed Ca in the soil to be tested 2+ and Sr 2+ The content was determined, and the c-value was calculated, where c = the adsorbed Ca content in the soil to be tested. 2+ Content / Adsorbed Sr in the soil to be tested 2+ Content; Weigh 200g (dry basis weight W) b 400g (dry basis mass W) of calcium and strontium adsorption type biochar granular material was placed in the material tank 1 of the soil desorption container. s The soil to be tested was evenly placed in the soil tanks 2 on both sides of the material tank 1, and compacted tightly to ensure full contact between the soil and the biochar granules. It was then left to stand for 3 days. Ⅲ. Remove slide plate 3, take out the calcium and strontium adsorbent biochar granules and re-stir and mix the biochar granules, then put them back into material tank 1, compact them tightly, so that the soil and biochar granules are in full contact, and let them stand for 3 days. IV. Repeat step III, remove slide 4, then take out the desorbed soil and measure the adsorbed Ca in the soil. 2+ and Sr 2+ Content, and calculate the value of a, where a = soil adsorbed Ca 2+ Content / Soil Adsorbed Sr 2+ The content is then calculated using the following formula to determine the Ca desorption from the biochar. 2+ Quantity C s Biochar desorption of Ca 2+ Quantity C b The desorption rate r was calculated, and the results are shown in Table 4.
[0030] C s =Soil adsorbed Ca 2+ Content × (ca) / (cb) C b =C s ×(W s / W b ) r=C b / Ca in the exchange medium 2+ Content × 100% Table 4
[0031] Cs=8.67×(193.02-176.94) / (193.02-102.49)=1.54 C b =1.54×(400 / 200)=3.08 cmol / kg r = 3.08 / 83.22 × 100% = 3.7% Example 3 Preparation of biochar: Corn stalks are sawn into particles of 2-4 mm in size and placed at 400℃ for high-temperature pyrolysis for 2 hours to obtain biochar. The obtained biochar is washed with 10% hydrochloric acid to remove carbonates. Its basic properties are shown in Table 5 below.
[0032] Soil: The soil was collected from Qianxi County, Guizhou Province. The soil type is yellow soil, and the texture is medium loam. Tobacco has been grown there for a long time. The basic properties of the soil are shown in Table 5 below.
[0033] Table 5
[0034] A method for preparing calcium and strontium adsorbent biochar particulate material includes the following steps: S1: Wash the carbonates in the biochar with 0.05M hydrochloric acid, rinse off the residual hydrochloric acid with water, and dry at 40℃. Then, take 20g of the dried biochar and put it into a 150mL centrifuge tube, add 80mL of 0.5M NaCl solution, and shake at 150r / min for 60min at room temperature on a reciprocating shaker. After filtration, wash the filter residue three times with 0.1M NaCl solution, and then wash it three times with water to obtain NaCl. + Adsorbed biochar; S2: Prepare a calcium-strontium mixed chloride solution with a total concentration of 0.1M, wherein Ca... 2+ and Sr 2+ The molar ratio is 5:1; Na is added according to a material-to-liquid ratio of 1g:4mL. + The adsorbent biochar was added to a calcium and strontium mixed chloride solution and shaken at 15°C for 60 min at a shaking rate of 150 r / min. The mixed solution was filtered off, and the filter residue was washed three times with 0.1 M NaCl solution and then washed three times with water. Finally, it was dried at 60°C until the moisture content was 30% to obtain calcium and strontium adsorbent biochar granular material.
[0035] A method for measuring desorbed Ca in soil based on calcium and strontium adsorption biochar granular materials 2+ The method of measurement includes the following steps: I. Take 20g of calcium-strontium adsorbent biochar granules and add them to 80 mL of 1.0M FeCl2 solution with pH=4.0. Shake at 15℃ for 60 min at a shaking rate of 150 r / min. Filter to obtain the exchange solution; test the Ca content in the exchange solution. 2+ and Sr 2+ The content is calculated, and the b value is determined, where b = Ca of the exchange liquid. 2+ Content / Sr in exchange medium 2+ content; II. Determination of adsorbed Ca in the soil to be tested 2+ and Sr 2+ The content was determined, and the c-value was calculated, where c = the adsorbed Ca content in the soil to be tested. 2+ Content / Adsorbed Sr in the soil to be tested 2+ Content; Weigh 200g (dry basis weight W) b 400g (dry basis mass W) of calcium and strontium adsorption type biochar granular material was placed in the material tank 1 of the soil desorption container. s The soil to be tested was evenly placed in the soil tanks 2 on both sides of the material tank 1, and compacted tightly to ensure full contact between the soil and the biochar granules. It was then left to stand for 3 days. Ⅲ. Remove slide plate 3, take out the calcium and strontium adsorbent biochar granules and re-stir and mix the biochar granules, then put them back into material tank 1, compact them tightly, so that the soil and biochar granules are in full contact, and let them stand for 3 days. IV. Repeat step III, remove slide 4, then take out the desorbed soil and measure the adsorbed Ca in the soil. 2+ and Sr 2+ Content, and calculate the value of a, where a = soil adsorbed Ca 2+ Content / Soil Adsorbed Sr 2+ The content is then calculated using the following formula to determine the Ca desorption from the biochar. 2+ Quantity C s Biochar desorption of Ca 2+ Quantity C b The desorption rate r was calculated, and the results are shown in Table 6.
[0036] C s =Soil adsorbed Ca 2+ Content × (ca) / (cb) C b =C s ×(W s / W b ) r=C b / Ca in the exchange medium 2+ Content × 100% Table 6
[0037] Cs=22.36×(132.86-16.56) / (132.86-4.94)=20.33 C b =20.33×(400 / 200)=40.66cmo / kg r = 40.66 / 45.54 × 100% = 89.3% Example 4 The preparation method of biochar is the same as in Example 3.
[0038] Test water: Taken from a winter wheat field at the Experimental Station of China Agricultural University in Shangzhuang Town, Haidian District, Beijing, it was shallow groundwater at a depth of 120cm, and its basic properties are shown in Table 7. The preparation method of calcium-strontium adsorbent biochar granular material is the same as in Example 3.
[0039] Table 7
[0040] A method for measuring desorbed Ca in water based on calcium and strontium adsorption biochar granular materials 2+ The method of measurement includes the following steps: ① Add 20g of calcium-strontium adsorbent biochar granules to 80mL of 1.0M FeCl2 solution (pH=4.0), shake at 15℃ for 60min, and filter to obtain the exchange solution; test the Ca content in the exchange solution. 2+ and Sr 2+ The content is calculated, and the b value is determined, where b = Ca of the exchange liquid. 2 + Content / Sr in exchange medium 2+ content; ②Measure the adsorbed state of Ca in the test water 2+ and Sr 2+ The content was determined, and the c-value was calculated, where c = the adsorbed Ca content in the test water. 2+ Content / Adsorbed Sr in test water 2+ Content; 50g (dry basis weight W) b Calcium and strontium adsorbent biochar granules were placed in a nylon mesh bag with a pore size of 0.5 mm, and then the nylon mesh bag was placed into a 500 mL (W) container. w The water was left to stand for 3 days, during which it was stirred several times. ③ Remove the nylon mesh bag, filter the water, obtain the filtrate, and determine the Ca content in the filtrate. 2+ and Sr 2+ The content of Ca in the filtrate is calculated, and the value of a is determined, where a = Ca in the filtrate. 2+ Content / Sr in filtrate 2+ The content is then calculated using the following formula to determine the Ca desorption from the biochar. 2+ Quantity C w Biochar desorption of Ca 2+ Quantity C b The desorption rate r was calculated; the results are shown in Table 8.
[0041] C w =Ca in the filtrate 2+ Content × (ca) / (cb) C b =C s ×(W s / W b ) r=C b / Ca in the exchange medium 2+ Content × 100% Table 8
[0042] Cw=47.6×(1317-1240) / (1137-4.94)=2.82 Cb = 2.82 × (500 / 50) = 28.2 mmol r = 28.2 / 45.54 × 100% = 61.9% While specific embodiments of the present invention have been described in detail, they should not be construed as limiting the scope of protection of the present invention. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of the present invention.
Claims
1. A method of preparing a calcium strontium adsorptive biochar particulate material, characterized by, The method comprises the following steps: S1: washing the biochar with acid, then adding the washed biochar to a sodium chloride solution and performing oscillation, and filtering to obtain Na + adsorbed biochar; S2: Preparation of Ca 2+ and Sr 2+ A calcium-strontium mixed chloride solution with a molar ratio of 50:1-10 is prepared. The Na + The adsorptive biochar is added to the calcium-strontium mixed chloride solution and shaken. After filtration, washing and drying, a calcium-strontium adsorptive biochar granular material is obtained.
2. The method of claim 1, wherein the calcium and strontium adsorptive biochar particulate material is prepared by: The particle size of the biochar is 2-5 mm; the acid is hydrochloric acid with a concentration of 0.05 M; the concentration of the sodium chloride solution is 0.5 M; and the ratio of the biochar to the sodium chloride solution is 1 g:4 mL.
3. The method of claim 1, wherein the calcium and strontium adsorptive biochar particulate material is prepared by: Na + The adsorption type biochar and calcium strontium mixed chloride solution were 1g:4mL.
4. The method of claim 1, wherein the calcium and strontium adsorptive biochar particulate material is prepared by: The oscillation rate is 150 r / min, and the oscillation time is 60 min.
5. The method of claim 1, wherein the calcium and strontium adsorptive biochar particulate material is prepared by: The drying temperature is 30-60 DEG C, and the drying is performed until the water content is 30%.
6. The calcium-sorbing biochar granular material prepared by the method of any one of claims 1-5.
7. A method of measuring adsorbed Ca 2+ desorption amount based on calcium-strontium adsorbed type biochar granular material, characterized by, Measuring desorbed Ca in soil 2+ The method comprises the following steps: I. The calcium and strontium adsorption type of charcoal granular material is added to the FeCl2 solution with pH=4 and oscillated. After filtration, the exchange solution is obtained, and then the Ca 2+ and Sr 2+ contents in the exchange solution are determined. II. Determination of adsorbed Ca in the soil to be tested 2+ and Sr 2+ Content; The mass of W b The calcium and strontium adsorbent biochar granules were placed in the material tank (1), and a mass of W was added. s The soil to be tested was placed in a soil trough (2) and left for 3 days; III. The calcium-sorbing biochar granular material is taken out and stirred and mixed, and then is placed in the material tank (1) again and is placed for 3 days. IV. Repeat step III and then remove the soil and measure the soil adsorbed Ca 2+ and Sr 2+ content and calculate the biochar desorbed Ca 2+ amount C s from the soil using the following equation: C s = soil adsorbed Ca 2+ content x (c-a) / (c-b), Where c = soil adsorbed Ca 2+ content / soil adsorbed Sr 2+ content; a = soil adsorbed Ca 2+ content / soil adsorbed Sr 2+ content; b = exchangeable Ca 2+ content / exchangeable Sr 2+ content; biochar desorbed Ca 2+ amount C b , C b =C s ×(W s / W b ); Measuring desorbed Ca in water bodies 2+ The amount includes the following steps: ① The calcium and strontium adsorption type of charcoal granular material is added to the FeCl2 solution with pH = 4 and oscillated, and the exchange solution is obtained after filtration, and then the Ca 2+ and Sr 2+ contents in the exchange solution are determined; (ii) determining the adsorbed Ca 2+ and Sr 2+ content of the water to be tested; placing calcium-sorbing biochar granular material having a mass of W b in a nylon mesh bag, and then placing the nylon mesh bag in the water to be tested having a volume of W w for 3 days; ③ Take out the nylon mesh bag, filter the water to be tested, and measure the Ca 2+ and Sr 2+ content in the filtrate, and calculate the amount of Ca 2+ desorbed by the biochar in the water body according to the following formula: C w , C w =Ca in the filtrate 2+ Content × (ca) / (cb) Where c = adsorbed Ca content of water under test 2+ Where c = adsorbed Sr content of water under test 2+ Where a = Ca content of filtrate 2+ Where a = Sr content of filtrate 2+ Where b = Ca content of exchange 2+ Where b = Sr content of exchange 2+ Where b = Ca content of exchange 2+ Where b = Sr content of exchange b Where b = Ca content of exchange C b =C w ×(W w / W b ).
8. The calcium-strontium adsorbed biochar granular material according to claim 7, wherein the adsorbed Ca 2+ The method for desorbing the amount, characterized by: The concentration of the FeCl2 solution in step I and step ① is 1.0 M; and the ratio of the calcium-sorbing biochar granular material to the FeCl2 solution is 1 g:4 mL.
9. The calcium-strontium adsorbed biochar granular material based on claim 7 adsorbed state Ca 2+ The method for desorbing the amount, characterized by: The oscillation rate is 150 r / min, and the oscillation time is 60 min.
10. The calcium-strontium adsorbed biochar granular material based on claim 7 adsorbed state Ca 2+ The method for desorbing the amount, characterized by: The nylon mesh bag has a pore size of 0.5 mm.