CN116116388A - Preparation method and application of biochar/magnesium aerogel bead dephosphorization adsorbent - Google Patents
Preparation method and application of biochar/magnesium aerogel bead dephosphorization adsorbent Download PDFInfo
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- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 description 2
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
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Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
- B01J20/24—Naturally occurring macromolecular compounds, e.g. humic acids or their derivatives
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
- B01J20/28047—Gels
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/28—Treatment of water, waste water, or sewage by sorption
- C02F1/288—Treatment of water, waste water, or sewage by sorption using composite sorbents, e.g. coated, impregnated, multi-layered
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/105—Phosphorus compounds
Abstract
The invention discloses a preparation method of a biological carbon/magnesium aerogel bead dephosphorization adsorbent and application thereof in adsorption and recovery of phosphorus, wherein the preparation method comprises the following steps: preparation of sludge biochar: dewatering sludge in N 2 Carbonizing at 400-800 deg.c; adding the sludge into HCl solution, stirring, washing, drying, grinding and sieving to obtain washed sludge biochar; preparation of aerogel beads: dissolving chitosan in acetic acid solution, adding the cleaned sludge biochar after uniform mixing, stirring, and adding MgCl 2 Continuing stirring; mixing the mixed solution at uniform speed by using a syringeDripping into alkaline aqueous solution, standing and cleaning; immersing in glutaraldehyde solution and cleaning; freeze drying to constant weight. The prepared biological carbon/magnesium aerogel bead dephosphorization adsorbent has high adsorption capacity, easy recovery and high physical and chemical stability, and can be manufactured and applied in large scale.
Description
Technical Field
The invention belongs to the field of water pollution treatment, and particularly relates to a preparation method and application of a biochar/magnesium aerogel bead dephosphorization adsorbent.
Background
The eutrophication of water is a serious challenge in the field of water pollution control all the time, and the excessive accumulation of phosphorus elements in the water environment can be reduced, so that the eutrophication phenomenon of the water can be effectively controlled. In actual sewage treatment, the concentration of phosphorus in sewage is mostly reduced by means of biological treatment, chemical precipitation, adsorption and other methods. However, biological treatment and chemical precipitation methods generate a large amount of excess sludge, increasing the treatment cost of sewage treatment plants. In contrast, the adsorption method is considered to be one of the best choices for removing phosphate because of its high removal rate, simple operation, and low cost.
The surplus sludge is used as a byproduct of a sewage treatment plant, and has high daily yield and high hazard. However, the sludge contains abundant carbon content, so that the sludge is used as a biomass raw material to prepare biochar, which is a research hot spot. However, during actual operation of a sewage treatment plant, the powdered biochar adsorbent is largely lost during the recovery process, and may clog or damage the water treatment system, and is difficult to separate from the water environment and recycle. Meanwhile, the selectivity and affinity of the biochar to phosphorus are weak.
In view of the above, it is necessary to provide a simple and efficient method for preparing a biochar dephosphorizing adsorbent, which has the advantages of high adsorption capacity, easy recovery and strong physicochemical stability.
Disclosure of Invention
The invention aims to provide a simple and efficient preparation method of a biochar dephosphorization adsorbent, which aims to solve the problems that a powdery biochar adsorbent material in the prior art is difficult to recycle and has weak selectivity to phosphorus.
The invention provides a preparation method of a biochar/magnesium aerogel bead adsorbent for achieving the purposes, which comprises the following steps:
s1, preparing sludge biochar: the dehydrated petrochemical sludge is treated in N 2 Carbonizing at 400-800 deg.C for 2 hr under atmosphere, cooling to room temperatureObtaining biochar; adding the biochar into HCl solution, stirring at room temperature for 2-4h, removing impurities, cleaning, stirring at room temperature for 3h, and cleaning to obtain cleaned sludge biochar;
s2, preparation of aerogel beads: dissolving chitosan in acetic acid solution, mixing uniformly, adding the cleaned sludge biochar, and adding MgCl at room temperature 2 Continuing stirring; dripping the extrusion method into an alkaline aqueous solution, and chemically crosslinking at 2-5 ℃; cleaning, soaking in glutaraldehyde solution, cleaning, and lyophilizing to constant weight.
Preferably, the washed sludge biochar in the step S1 is dried to constant weight at 60-105 ℃ and then ground and passes through a 150-200 mesh screen; the cleaning method comprises the step of cleaning with deionized water.
Preferably, the concentration of the HCl solution in the step S1 is 1-2mol/L, and the ratio of the biochar to the HCl solution is 1g:20-50mL.
Preferably, the concentration of the acetic acid solution in step S2 is 1.5-2%; the ratio of chitosan to acetic acid solution is 1-4g:100mL.
Preferably, in the step S2, the mass ratio of the chitosan, the biochar and the Mg element is 1:1:0.2-0.6.
Preferably, the alkaline solution in step S2 comprises a solution containing NaOH and CH 3 Aqueous OH solution, naOH, CH 3 OH and H 2 The mass ratio of O is 1:2-5:4-7.
Preferably, the glutaraldehyde solution in step S2 has a concentration of 0.25% to 10%.
The invention provides a biochar/magnesium aerogel bead adsorbent prepared by the preparation method, which is of a reticular spherical structure.
The invention provides application of a biochar/magnesium aerogel bead adsorbent for adsorbing phosphorus.
Preferably, the device is used for adsorbing phosphorus in sewage.
Compared with the prior art, the invention has the beneficial effects that:
the invention uses chitosan as a natural organic polymer substance to form a gel material with a space network structure through the crosslinking action, and the prepared biological carbon/magnesium aerogel bead dephosphorization adsorbent has a reticular spherical structure, has developed internal pores and can provide enough active adsorption sites in the adsorption process. Compared with powdered biochar adsorbents in the prior art, the method is easier to separate from water. Compared with the common chitosan aerogel beads, the method has the advantages that the metal Mg element with stronger affinity and good selectivity to phosphorus is uniformly doped, so that the material has excellent phosphorus absorption performance. Compared with the existing phosphorus-absorbing gel material, the phosphorus-absorbing gel material has the advantage that the phosphorus-absorbing performance is enhanced by chelating metals such as lanthanum, zirconium and the like. The study firstly uses magnesium metal to modify gel materials, and has good phosphorus absorption effect. Experimental results show that compared with the biochar aerogel beads, the biochar/magnesium aerogel beads have the advantages that the adsorption rate of the biochar/magnesium aerogel beads is improved by 12.5% after magnesium is added, and the adsorption quantity of the biochar/magnesium aerogel beads to phosphorus is about 65mg/g. In general, the preparation method is simple and convenient to operate, high in repeatability and high in finished product yield, and the prepared biochar/magnesium aerogel bead dephosphorization adsorbent has the advantages of high adsorption capacity, good adsorption performance, easiness in recovery and strong physical and chemical stability, and is a dephosphorization adsorbent with industrial application prospect.
Drawings
FIG. 1 is a graph comparing the freeze-drying of aerogel beads prepared in example 1 of the present invention before and after lyophilization;
FIG. 2 is a SEM comparison of the aerogel beads prepared in example 1 of the invention before and after adsorbing phosphate;
FIG. 3 is an EDS spectrum of the aerogel beads prepared in example 1 of the present invention after adsorbing phosphate;
FIG. 4 is N before adsorption of aerogel beads prepared in example 1 of the present invention 2 Adsorption-desorption isotherms and pore size distribution maps;
FIG. 5 is a comparison of XRD patterns of aerogel beads prepared in example 1 of the present invention before and after adsorption of phosphate;
FIG. 6 is a graphical representation of FTIR spectra before and after adsorption of phosphate by aerogel beads prepared in example 1 of the present invention;
FIG. 7 is a comparison of XPS spectra of aerogel beads prepared in example 1 of the present invention before and after adsorption of phosphate;
FIG. 8 is a time-swelling plot of aerogel beads prepared in example 1 of the present invention;
FIG. 9 is a graph of time-adsorption capacity of phosphate adsorbed by aerogel beads prepared in example 1 of the present invention;
FIG. 10 is a graph of adsorption capacity and pH for aerogel beads prepared in example 1 of the present invention when equilibrium is achieved in phosphate solutions of different initial pH;
FIG. 11 is a graphical representation of the adsorption equilibrium achieved by the aerogel beads prepared in example 1 of the present invention in phosphate solutions of different initial pH;
FIG. 12 is a graph showing the effect of glutaraldehyde crosslinking agent concentration on actual adsorption capacity for the aerogel beads prepared in example 1 of the present invention.
Detailed Description
The invention is further illustrated below in connection with specific examples, but is not limited in any way.
The test methods described in the following examples, unless otherwise specified, are all conventional; the reagents and materials, unless otherwise specified, are commercially available.
Example 1
The preparation method of the biochar/magnesium aerogel beads comprises the following steps:
the first step: drying dewatered petrochemical sludge (dehydrated petrochemical sludge with water content of 20-25%, metal Pt content of 10-15%, metal Si content of about 2% and metal Al content of about 2%) in 105 deg.C oven until constant weight, grinding, sieving, spreading in alumina corundum ark, and adding into N in tubular furnace 2 Keeping the temperature at 600 ℃ for 2 hours under the condition, cooling to room temperature, and taking out to obtain sludge biochar; adding the biochar into 2mol/LHCl solution (solid-to-liquid ratio is 1g:20 mL), magnetically stirring at room temperature for 3h by using a magnetic stirrer, and washing with deionized water until the pH is neutral; drying the cleaned sludge biochar in a baking oven at 60 ℃, grinding and sieving, and collecting the dried sludge biochar for subsequent gel bead preparation;
and a second step of: chitosan was dissolved in 2% acetic acid solution (solid to liquid ratio 1g:50 ml),adding the cleaned sludge biochar after the solution is uniformly mixed, magnetically stirring for 30min at room temperature, and adding MgCl 2 Stirring is continued for 30min, and the mass ratio of chitosan, biochar and Mg element is 1:1:0.6; the mixed solution was added dropwise to an aqueous alkaline solution (NaOH, CH) at an average rate using an extrusion method, i.e., using a 1mL syringe 3 OH and H 2 O mass ratio is 1:5:4), standing for 24 hours at the temperature of 4 ℃, and cleaning with deionized water; soaking in 1% glutaraldehyde solution for chemical crosslinking for 24 hr, and washing to obtain hydrogel beads; and freeze-drying to constant weight to obtain aerogel beads, and sealing and storing in a dry glass container.
As shown in FIG. 1, there is a comparative graph of the aerogel beads prepared in example 1 of the present invention before and after lyophilization, wherein (a) is before lyophilization and (b) is after lyophilization, the aerogel beads have diameters of 3mm before and after lyophilization.
FIG. 2 is a SEM image of the aerogel beads prepared in example 1 of the present invention before and after adsorption of phosphate, wherein (a-c) before adsorption and (d-f) after adsorption; (a) And (d) are respectively an integral diagram before adsorption and an integral diagram after adsorption, and the surface of the material after adsorption is rough and is wrapped by massive precipitates; (b) And (e) are cross-sectional views before and after adsorption, respectively, the material before adsorption is distributed with more honeycomb hole structures; (c) And (f) are surface patterns before and after adsorption, respectively, and the surface of the material after adsorption is almost completely covered by massive precipitates.
As shown in figure 3, the EDS spectrum of the aerogel beads prepared in the embodiment 1 of the invention after adsorbing phosphate can be seen that Mg and P elements are uniformly distributed on the surface of the material, and C, O and Mg elements uniformly distributed indicate that the biochar/magnesium aerogel bead skeleton is successfully constructed, and the P element is uniformly dispersed on the surface of the material in the adsorption process through physical and chemical adsorption, electrostatic action and the like.
As shown in FIG. 4, the aerogel beads prepared in example 1 of the present invention were N before adsorption 2 Adsorption-desorption isotherm and pore diameter distribution diagram, wherein the inset is the pore diameter distribution diagram of the material, the specific surface area of the material is 239.7m 2 Per g, pore volume of 0.37cm 3 The pore diameter is evenly distributed between 2nm and 15nm, and belongs to mesoporous materials.
As shown in FIG. 5, the XRD patterns of the aerogel beads prepared in example 1 of the present invention before and after adsorption of phosphate have diffraction peaks of Mg element before and after adsorption, which indicates that Mg element is successfully doped on the gel skeleton and Mg appears after adsorption 3 (PO 4 ) 2 、Mg 2 P 2 O 7 、NH 4 MgPO 4 ·6H 2 O、(NH) 4 MgH 2 P 3 O 10 Indicating that phosphate is adsorbed and forms a precipitate on the surface of the aerogel beads by Mg-O action.
As shown in FIG. 6, the FTIR spectrum before and after adsorbing phosphate was obtained by the aerogel beads prepared in example 1 of the present invention, which is shown at 579cm -1 、866cm -1 The P-O absorption peak intensity around the wavelength is increased, which indicates that phosphate in the solution is adsorbed on the surface of the material; at 490cm -1 The left and right absorption peaks correspond to Mg-O metal oxygen bonds, and the decrease in the strength of the Mg-O peaks after adsorption indicates that Mg-O plays an important role in phosphate adsorption.
As shown in fig. 7, XPS spectra of the aerogel beads prepared in example 1 of the present invention before and after adsorption of phosphate are shown; the characteristic peak of Mg1s (1304.1 eV) shows that Mg element is doped on the skeleton of the aerogel beads, and the characteristic peak of P2P (134.1 eV) after adsorption shows that phosphate is adsorbed on the aerogel bead material of the invention.
FIG. 11 is a physical diagram showing the adsorption equilibrium of the aerogel beads prepared in example 1 of the present invention in phosphate solutions of different initial pH, wherein the aerogel beads in an Erlenmeyer flask having an initial pH of 2 have been dissolved and broken.
Example 2:
determination of the swelling degree of the aerogel bead adsorbent prepared in example 1 in an aqueous solution:
the degree of swelling was determined by immersing the dried aerogel bead adsorbent prepared in example 1 in distilled water, with an initial mass of W 0 . Taking out the beads at regular time and sucking the surface water with filter paper, the mass is W t . The data were recorded periodically until the mass of the gel beads did not change.
As shown in fig. 8, which is a time-swelling diagram of the aerogel beads prepared in example 1 of the present invention, the aerogel beads have a low swelling degree in an aqueous solution, and maintain a stable physical structure during adsorption.
Wherein, the calculation formula of the swelling degree (SR) is as follows:
wherein W is 0 Is the dry mass of the sample, W t Is the mass of the sample after swelling in aqueous solution.
Example 3:
the aerogel beads prepared in example 1 were used as phosphorus adsorbents by the following steps:
0.03g of the adsorbent prepared in example 1 was charged into a conical flask containing 80mL of phosphate solution (20 mgP/L), and the pH of the solution was adjusted to 3 with 0.1M HCl or NaOH. Shaking at 180r/min in a constant temperature shaker at 303.15K. Three parallel experiments were set up and at certain time intervals (after adsorption for 1, 2, 3, 6, 12, 24, 36, 48 hours) 1mL of sample was withdrawn and filtered through a 0.22 μm nylon membrane filter. The obtained supernatant was subjected to determination of the phosphate concentration by ammonium molybdate spectrophotometry. FIG. 9 is a graph showing the relationship between the time-adsorption amount and the time-phosphate concentration of the aerogel beads prepared in example 1 according to the present invention; as can be seen, the adsorption of phosphorus by the aerogel beads was about 25mg/g when the initial phosphate solution concentration was about 20 mg/L.
Example 4:
0.03g of the adsorbent prepared in example 1 was charged into a conical flask containing 80mL of phosphate solution (40 mgP/L) and the pH of the solution was adjusted to 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 with 0.1M HCl or NaOH, respectively. At 303.15K, the mixture was shaken in a constant temperature shaker at 180r/min for 48h. Three sets of parallel experiments were set up using the same sampling and testing methods as in example 3. As shown in fig. 10, the adsorption capacity of the aerogel beads prepared in example 1 of the present invention when they reach adsorption equilibrium in phosphate solutions with different initial pH and the pH of the solution at equilibrium are shown; the analysis may be made such that,the electrostatic effect and the ion exchange effect play an important role in the adsorption process of the material; the isoelectric point of the aerogel beads is within 3-4; when the pH value of the solution is lower than 3, the aerogel bead structure is dissolved by acid (as shown in a physical diagram in FIG. 11), and the adsorption effect cannot be achieved; when the pH value of the solution is near the isoelectric point, the surface of the aerogel beads carries positive charges and can electrostatically attract phosphate anions carrying negative charges; when the pH value of the solution is higher than 6, the surface charge of the adsorbent is negative, and the adsorbent generates repulsive interaction with phosphate anions, so that the adsorption of the material to phosphate is inhibited; the pH value of each solution with different initial pH values is about 10 at the adsorption equilibrium, which indicates the OH on the surface of the material in the adsorption process - Ion exchange with phosphate anions in the solution occurs and is continuously released into the solution.
Example 5:
in order to obtain aerogel bead materials having good chemical stability, the glutaraldehyde concentrations were set to 0.25%, 1%, 2%, 3%, 4%, 5%, 10%, respectively, unlike the second step of example 1. 0.03g of the adsorbent prepared above was charged into an Erlenmeyer flask containing 80mL of a phosphate solution (40 mgP/L), and the pH of the solution was adjusted to 3 with 0.1M HCl or NaOH, respectively. Shaking at 180r/min in a constant temperature shaker at 303.15K. Three sets of parallel experiments were set up and 3mL samples were withdrawn after adsorption equilibration and filtered through a 0.22 μm nylon membrane filter. The obtained supernatant was spectrophotometrically measured for phosphate concentration by an ammonium molybdate method, and the Chemical Oxygen Demand (COD) in the solution was measured by a rapid digestion method. As shown in fig. 12, the influence of glutaraldehyde crosslinking agent concentration used in the preparation process of the aerogel beads prepared in example 1 of the present invention on the actual adsorption capacity is shown, and the concentration of organic matters in the solution after adsorption is studied; it can be seen that the material prepared by the method of example 1 has the best adsorption performance and the best chemical stability in the adsorption process.
Comparative example 1
Using commercial active carbon on the market, dissolving chitosan in 2% acetic acid solution (solid-liquid ratio is 1g:50 mL) under the same experimental condition, adding commercial active carbon after the solution is uniformly mixed, magnetically stirring at room temperature for 30min, and adding MgCl 2 Stirring is continued for 30min, and the mass ratio of chitosan, commercial activated carbon and Mg element is 1:1:0.6; the mixed solution was added dropwise to an aqueous alkaline solution (NaOH, CH) at an average rate using an extrusion method, i.e., using a 1mL syringe 3 OH and H 2 O mass ratio is 1:5:4), standing for 24 hours at the temperature of 4 ℃, and cleaning with deionized water; soaking in 1% glutaraldehyde solution for chemical crosslinking for 24 hr, and washing to obtain hydrogel beads; and freeze-drying to constant weight to obtain aerogel beads, and sealing and storing in a dry glass container.
The adsorption rate of phosphate is improved by about 95.3% in example 1 of the present invention compared with comparative example 1. The reason is analyzed, the high-concentration hydrochloric acid is used for cleaning the biochar prepared by the method, and the step greatly reduces the ratio of ash content in the biochar, so that the specific surface area of the activated carbon is increased, and the phosphorus absorption activity of the activated carbon is enhanced.
Many possible variations and modifications of the disclosed technology can be made by anyone skilled in the art without departing from the scope of the technology, or the technology can be modified to be equivalent. Therefore, any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention shall still fall within the scope of the technical solution of the present invention.
Claims (10)
1. The preparation method of the biochar/magnesium aerogel bead adsorbent is characterized by comprising the following steps of:
s1, preparing sludge biochar: the dehydrated petrochemical sludge is treated in N 2 Carbonizing at 400-800 ℃ in the atmosphere, and cooling to room temperature to obtain biochar; adding the biochar into HCl solution, stirring at room temperature until impurities are removed, and then cleaning to obtain cleaned sludge biochar;
s2, preparation of aerogel beads: dissolving chitosan in acetic acid solution, mixing uniformly, adding the cleaned sludge biochar, and adding MgCl at room temperature 2 Continuing stirring; dripping the extrusion method into an alkaline aqueous solution, and chemically crosslinking at 2-5 ℃; cleaning, soaking in glutaraldehyde solutionCleaning, and lyophilizing to constant weight.
2. The method for preparing the charcoal/magnesium aerogel bead adsorbent according to claim 1, wherein the washed sludge charcoal in step S1 is dried to constant weight at 60-105 ℃, and then ground and passed through a 150-200 mesh screen; the cleaning method comprises the step of cleaning with deionized water.
3. The method for preparing the charcoal/magnesium aerogel bead adsorbent according to claim 1, wherein the concentration of the HCl solution in step S1 is 1-2mol/L, and the ratio of charcoal to HCl solution is 1g:20-50mL.
4. The method for preparing a biochar/magnesium aerogel bead adsorbent according to claim 1, wherein the concentration of the acetic acid solution in step S2 is 1.5-2%; the ratio of chitosan to acetic acid solution is 1-4g:100mL.
5. The method for preparing the charcoal/magnesium aerogel bead adsorbent according to claim 1, wherein the mass ratio of chitosan, charcoal and Mg element in step S2 is 1:1:0.2-0.6.
6. The method for preparing a biochar/magnesium aerogel bead adsorbent as claimed in claim 1, wherein the alkaline solution in step S2 comprises a solution containing NaOH and CH 3 Aqueous OH solution, naOH, CH 3 OH and H 2 The mass ratio of O is 1:2-5:4-7.
7. The method for preparing a biochar/magnesium aerogel bead adsorbent according to claim 1, wherein the glutaraldehyde solution in step S2 has a concentration of 0.25% -10%.
8. The biochar/magnesium aerogel bead adsorbent prepared by the preparation method of any one of claims 1 to 7, which is of a reticular spherical structure.
9. The application of the biochar/magnesium aerogel bead adsorbent is characterized by being used for adsorbing phosphorus.
10. The use of the biochar/magnesium aerogel bead adsorbent of claim 9 for adsorbing phosphorus in sewage.
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