Titanium-loaded microorganism solidified particle water treatment agent and preparation method thereof

Abstract

The invention discloses a titanium-loaded microorganism solidified particle water treatment agent and a preparation method thereof, and relates to the technical field of water treatment. The titanium-loaded microorganism solidified particle water treatment agent is prepared from a citric acid and titanium dioxide dual modified adsorbent, a magnetic stripping bentonite-based aerogel material, bacillus subtilis and Sporidiomyces sp. Active thalli of bacillus subtilis and Sporidiomyces sp. Are loaded on a citric acid and titanium dioxide dual modified adsorbent, and then form mechanical interlocking with a magnetic stripping bentonite-based aerogel material, so that the pore structure is enriched, the adsorption sites are increased, the adsorption capacity of the water treatment agent on heavy metal ions and organic pollutants is enhanced, and the adsorption capacity of the water treatment agent on heavy metal ions and organic pollutants is improved. The curing property on microorganisms is also improved, the adverse effect of an acid-base environment on the microorganisms is reduced, the microorganisms are combined with a functional material, the adsorption and decomposition effects are fully exerted, and various pollutants in a water body are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and specifically relates to a titanium-loaded microbial solidified particle water treatment agent and a preparation method thereof. Background Art

[0002] With the acceleration of the urbanization process, the expansion of industrial activities, and the impact of climate change, the emissions of domestic sewage and industrial wastewater continue to increase. The large amounts of heavy metals (such as Pb 2+ , Cd 2+ ), phosphates, organic pollutants (such as antibiotics) and other harmful substances in it pose a serious threat to the water environment quality, not only damaging the ecological environment but also threatening human health. At the same time, the problem of water resource shortage is becoming increasingly prominent, prompting people to pay more attention to the resource utilization and sustainable development of sewage. In this context, the sewage treatment industry is undergoing a transformation from traditional end-of-pipe treatment to the directions of intelligence, resource utilization, and low carbon.

[0003] The methods for treating water pollution include physical methods, chemical methods, and biological methods. Among them, the biological method realizes the purification of water quality by the metabolic function of microorganisms to decompose, absorb, or adsorb pollutants, and has the characteristics of low cost, safety, and no pollution, and is the main way of sewage treatment today.

[0004] Currently, the existing technologies mainly have the following problems:

[0005] The activity of microorganisms is easily affected by the adverse water environment, which limits the adsorption and degradation of pollutants by the bacterial cells. And due to the limited surface sites of microorganisms, the adsorption performance is weak, thus unable to achieve an effective water purification effect. Summary of the Invention

[0006] In view of the above situation, to overcome the defects of the existing technologies, the present invention provides a titanium-loaded microbial solidified particle water treatment agent, which comprises the following components in parts by weight: 50-60 parts of a citric acid and titanium dioxide dual-modified adsorbent, 20-30 parts of a magnetic exfoliated bentonite-based aerogel material, 1-2 parts of Bacillus subtilis, and 1-2 parts of Saccharomyces fibuligera.

[0007] The citric acid and titanium dioxide dual-modified adsorbent comprises the following components in parts by weight: 30-40 parts of sea urchin-shaped magnetic composite nanoparticles, 10-20 parts of citric acid, and 6-10 parts of nano-titanium dioxide.

[0008] The magnetic exfoliated bentonite-based aerogel material comprises the following components in parts by weight: 5-8 parts of magnetic exfoliated bentonite, 8-10 parts of carboxylated cellulose nanofibers, and 1-3 parts of polyethyleneimine.

[0009] The preparation method of the citric acid and titanium dioxide dual-modified adsorbent specifically comprises the following steps:

[0010] (1) Dissolve 3.5 g of ferric chloride hexahydrate in 40 mL of ethylene glycol. Add 3.7 g of anhydrous sodium acetate under stirring at a speed of 1000 - 2000 rpm until completely dissolved. Subsequently, transfer it to a 50 mL polytetrafluoroethylene liner, seal it, place it in a reaction kettle, and keep it at 180 - 200 °C for 10 - 12 h. Collect the precipitate by magnetic separation, wash it with deionized water and absolute ethanol, and then vacuum dry it at 60 °C. The magnetic Fe 3 O 4 microspheres are obtained by hydrothermal synthesis method. Their surfaces are rich in active sites, which can adsorb heavy metal ions and pollutants through electrostatic interaction or coordination bonds, can generate hydroxyl radicals through chemical catalysis to degrade refractory organic matters such as antibiotics, and can also reduce highly toxic pollutants to low-toxicity forms for subsequent degradation treatment, obtaining Fe 3 O 4 microspheres;

[0011] (2) Disperse the Fe 3 O 4 microspheres described in step (1) in a mixed solution of 30 mL of absolute ethanol and 3 mL of water, ultrasonicate for 3 - 5 min, then successively add 1 mL of ammonia water, 10 mL of absolute ethanol and 0.3 - 0.5 mL of tetraethyl orthosilicate, and ultrasonicate at 20 - 30 °C for 2 - 3 h. Collect the precipitate by magnetic separation, wash it with deionized water and absolute ethanol, and then vacuum dry it at 60 °C. The silica is coated on the surface of the Fe 3 O 4 microspheres. The introduction of silanol groups enhances the adsorption capacity for heavy metal ions and organic pollutants. The silica coating layer can not only prevent the aggregation between Fe 3 O 4 microspheres, expose more active sites to improve the adsorption efficiency, but also broaden the pH range of use. Even in an acidic environment, it can prevent the oxidation or dissolution of Fe 3 O 4 and improve the stability and recyclability of the material, obtaining modified Fe 3 O 4 microspheres;

[0012] (3) Add sodium aluminate powder to 30 mL of water, stir until dissolved, add 0.3 - 0.5 g of urea, stir for 0.5 - 1 h, then add the modified Fe 3 O 4 microspheres described in step (2), ultrasonicate for 1 - 2 h, then transfer it to a reaction kettle, react at 160 - 180 °C for 5 - 6 h, collect the product by magnetic separation, wash it with deionized water 3 - 5 times, and then vacuum dry it at 50 °C. The addition of urea will make more hydroxides in the solution, thus increasing OH -concentration to promote the formation of layered or fibrous crystals. When OH - and AL 3+ are supersaturated in the solution, the formed boehmite grows densely on the surface of the modified Fe 3 O 4 microspheres, presenting a hierarchical sea urchin-like core-shell structure. Its porous network is conducive to the adsorption of heavy metals, organic pollutants in water and the immobilization of microorganisms. Among them, boehmite can provide attachment sites for microorganisms to form a local microenvironment, reduce the impact of acid-base on microorganisms, and the surface hydroxyl groups form hydrogen bonds or coordination bonds with the extracellular polymers of microorganisms to enhance the immobilization effect of microorganisms. At the same time, boehmite can wrap the microbial cells to form an isolation layer to hinder the penetration of H + and OH - , reduce the damage of the acid-base environment to microorganisms, enhance the colonization density and activity of microorganisms, and obtain sea urchin-like magnetic composite nanoparticles;

[0013] (4) Dissolve 1.0 - 2.0 g of citric acid in 100 mL of water to form a citric acid solution for later use. Disperse the sea urchin-like magnetic composite nanoparticles described in step (3) in 40 mL of dimethyl sulfoxide and stir at a speed of 100 - 200 rpm for 12 h. Then add 6 mL of tetraethyl orthosilicate and continue to stir for 3 - 5 h. Next, add 0.6 - 1.0 g of titanium dioxide nanoparticles and stir for 8 - 12 h. Centrifuge, wash the precipitate twice with distilled water, dry it in vacuum and then immerse it in the citric acid solution, stir at a speed of 100 - 200 rpm in a nitrogen atmosphere for 24 h, and then dry it in vacuum. The chelating effect of citric acid can partially dissolve the amorphous region of boehmite and form a richer mesoporous structure in combination with titanium dioxide nanoparticles. After doping with titanium dioxide nanoparticles and acidifying with citric acid, not only the porosity and adsorption sites of the sea urchin-like magnetic composite nanoparticles are increased, thereby enhancing the adsorption capacity for heavy metal ions and organic pollutants, but also the physical embedding efficiency of microorganisms is improved, which is beneficial to the load stability of microorganisms. Among them, citric acid can promote the uniform dispersion of titanium dioxide nanoparticles, and the high hardness of titanium dioxide nanoparticles enhances the mechanical strength of the composite material and reduces the structural collapse during repeated use, obtaining a double-modified adsorbent of citric acid and titanium dioxide;

[0014] Preferably, in step (3), the addition amount of sodium aluminate is 0.1 - 0.2 g. Sodium aluminate releases aluminate ions in water and serves as the key aluminum source for the synthesis of boehmite. The alkaline environment of sodium aluminate can reduce the formation of amorphous aluminum hydroxide or gibbsite, thereby selectively guiding the formation of boehmite;

[0015] Preferably, in step (4), the type of titanium dioxide nanoparticles is rutile, with a particle size of 100 - 300 nm, showing low photocatalytic activity to avoid the generation of harmful intermediate products, and also having good chemical stability and remaining stable in strong acids and strong alkalis.

[0016] The present invention also provides a method for preparing a titanium-carrying microbial solidified granular water treatment agent, which specifically comprises the following steps:

[0017] S1. Add 10.0 g of bentonite to a mixed solution of 500 mL of ultrapure water and anhydrous ethanol, wherein the volume ratio of ultrapure water to anhydrous ethanol is 1:2.5, and stir evenly. First, stir the mixed solution in a microwave at 600-800 W and 60 ° C for 1-2 h, and then perform ultrasonic dispersion treatment at 600-700 W for 1-2 h, and then vacuum dry at 60 ° C for 12 h to obtain a peeled bentonite sheet for standby use. Add 1.0-1.8 g of ferric chloride and 0.6 g of ferric dichloride to 100 mL of water, and sieve at 500-600 W and 60 ℃ for 3-5min, then add 10.5mL of ammonia water, continue stirring at 500-600W and 60℃ for 0.5-1h, then add the peeled bentonite flakes, stir thoroughly for 1-2h, cool to room temperature, collect the product by magnetic separation, wash with anhydrous ethanol and ultrapure water for many times until the pH reaches 7.0, finally vacuum dry and grind. The peeled bentonite has a larger specific surface area, and its layered structure exposes more active sites, which can adsorb and accommodate more pollutants. At the same time, combined with the magnetic component Fe 3 O 4 The catalytic effect further promotes the decomposition of pollutants to obtain magnetic exfoliation bentonite;

[0018] S2, add 0.8-1.0g carboxylated cellulose nanofibers into 100mL ultrapure water, stir magnetically to form a carboxylated cellulose nanofiber suspension, then add 50% polyethyleneimine solution and the magnetic exfoliation bentonite described in step S1, stir at 60-70°C for 3-4h, stirring at 200-300rpm, through this process, a uniform mesh porous structure is formed, which has slight wrinkles, can increase the adsorption performance of heavy metal ions and organic pollutants, wherein the network structure effectively protects the magnetic component Fe 3 O 4 The stability of the bentonite-based aerogel material can be used as a stable and reusable adsorption material in the field of water treatment to obtain a magnetically exfoliated bentonite-based aerogel material;

[0019] S3, 1.0-2.0g of Bacillus subtilis and 1.0-2.0g of Saccharomyces cerevisiae were inoculated into MSM basal salt medium, 1% glucose and 0.5% glycerol were added, and the pH was controlled to 6.5-7.0. The viable bacteria concentration reached 10 at 28-30°C and 150-200rpm. 8cfu / g to obtain a bacterial solution, which is centrifuged to discard the supernatant, and the active bacteria are collected. Then, the adsorbent modified by both citric acid and titanium dioxide is immersed in the MSM basal salt medium for 6 - 8 h, taken out and mixed with the active bacteria, and then freeze-dried. With the adsorbent modified by both citric acid and titanium dioxide as the carrier, the active bacteria form a biofilm or are directly adsorbed on the carrier, enhancing the stability of the bacteria in water, reducing the adverse effects of the acid-base environment on the bacterial activity, ensuring a relatively high activity of the bacteria, and being conducive to the purification of water by Bacillus subtilis combined with Saccharomyces fibuligera, to obtain titanium-loaded microbial solidified particles;

[0020] S4. Add the titanium-loaded microbial solidified particles described in step S3 into the magnetic exfoliated bentonite-based aerogel material described in step S2, and then perform ultrasonic dispersion treatment for 0.5 - 1 h, and then freeze-dry. The titanium-loaded microbial solidified particles form a mechanical interlock with the network structure of the magnetic exfoliated bentonite-based aerogel material in a sea urchin shape, increasing the structural stability, reducing the risk of aerogel collapse, broadening the pH usage range of the aerogel material, being conducive to the stability of recycling. Among them, the magnetic porous network enhances the adsorption stability of microorganisms, further protecting the activity of microorganisms. At the same time, the magnetic function enhances the adsorption performance of the composite material for pollutants. Combining with the decomposition of microorganisms, an efficient water purification effect is achieved, to obtain a titanium-loaded microbial solidified particle water treatment agent;

[0021] Preferably, in step S2, the diameter of the carboxylated cellulose nanofibers is 4 - 10 nm and the length is 1 - 3 μm. Carboxylated cellulose nanofibers with a suitable diameter size have a higher adsorption capacity, and the micron-scale fibers are more likely to form an intertwined porous network, improving the mechanical strength and elasticity, and being suitable for dynamic adsorption in water;

[0022] Preferably, in step S2, the addition amount of the polyethyleneimine solution is 0.1 - 0.3 g. Polyethyleneimine is rich in amino groups and can combine with heavy metal ions such as Pb 2+ 、Cd 2+ 、Hg 2+ etc. through coordination, electrostatic attraction or ion exchange, and can also adsorb organic pollutants such as phenols and antibiotics, and can act as a cross-linking agent, which not only increases the specific surface area and porosity of the aerogel, improves the adsorption capacity, but also improves the mechanical strength of the aerogel and enhances the structural stability of the aerogel in water.

[0023] The beneficial effects achieved by the present invention are as follows:

[0024] In the present invention, the active cells of Bacillus subtilis and Saccharomyces sphaerica are loaded on a double-modified adsorbent of citric acid and titanium dioxide to form titanium-loaded microbial solidified particles, which are then mechanically interlocked with a magnetic exfoliated bentonite-based aerogel material, further enriching the pore structure and increasing the adsorption sites. This not only enhances the adsorption capacity of the water treatment agent for heavy metal ions and organic pollutants but also improves the solidification property of microorganisms, reduces the adverse effects of the acid-base environment on microorganisms, combines microorganisms with functional materials, gives full play to the adsorption and decomposition effects, reduces various pollutants in water, and at the same time, the characteristics of high strength and magnetism endow the water treatment agent with good recycling stability, and it still has excellent water treatment effects after multiple uses; in the double-modified adsorbent of citric acid and titanium dioxide, first, boehmite is densely grown on the surface of the modified Fe 3 O 4 microspheres, presenting a hierarchical sea urchin-like core-shell structure. Its porous structure is beneficial for adsorbing heavy metals, organic pollutants in water, and solidifying microbial loading. Among them, silica and boehmite improve the uniform dispersion of Fe 3 O 4 microspheres, reduce the oxidation of Fe 3 O 4 microspheres, and also broaden the pH usage range, which has a positive effect on the stability of microorganisms and microsphere structures. Then, nano-titanium dioxide and citric acid are used to dope and acidify the sea urchin-like magnetic composite nanoparticles, increasing the adsorption sites and chemical stability, thereby enhancing the adsorption capacity of heavy metal ions and organic pollutants, improving the loading amount and loading stability of microorganisms, and reducing the damage of the acid-base environment to microorganisms. Among them, citric acid promotes the uniform dispersion of nano-titanium dioxide, so as to better play a protective role, and nano-titanium dioxide is beneficial to enhancing the mechanical strength and reducing the risk of collapse after the adsorbent is recycled; in the magnetic exfoliated bentonite-based aerogel material, the exfoliated bentonite lamellar structure is crosslinked with carboxylated cellulose nanofibers and polyethyleneimine to form a uniform three-dimensional network structure with slight wrinkles, increasing the adsorption capacity for heavy metal ions and organic pollutants, and the network structure effectively protects the magnetic component Fe 3 O 4Stability, where the exfoliated bentonite is dispersed in the aerogel matrix in the form of single-layer or few-layer nanosheets through physical cross-linking or chemical bonding, enhancing interfacial bonding, effectively dispersing stress, and improving the compressive and tensile strengths of the aerogel, thus being beneficial to the structural stability of the aerogel material; loading the titanium-loaded microbial solidified particles into the magnetic exfoliated bentonite-based aerogel material can not only reduce the agglomeration phenomenon of the titanium-loaded microbial solidified particles caused by the sea urchin shape, but also reduce the risk of aerogel collapse, broaden the pH usage range of the aerogel material, further protect the activity of the microorganisms and the structural stability of the water treatment agent, being beneficial to multiple recycling. At the same time, the dual magnetic materials increase the adsorption performance for pollutants, and combined with the decomposition effect of the microorganisms, an efficient water purification effect is achieved; the present invention uses a dual-modified adsorbent of citric acid and titanium dioxide, a magnetic exfoliated bentonite-based aerogel material, Bacillus subtilis and Saccharomyces sp. to prepare a water treatment agent of titanium-loaded microbial solidified particles, which can protect the activity of the microorganisms, enhance the adsorption performance for heavy metal ions and organic pollutants, and has an efficient purification effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a scanning electron micrograph of the water treatment agent of titanium-loaded microbial solidified particles prepared in Example 1 of the present invention;

[0026] Figure 2 It is a graph of the viable cell rate results of Examples 1-4 and Comparative Examples 1-3 of the present invention;

[0027] Figure 3 It is a graph of the pollutant adsorption amount results of Examples 1-4 and Comparative Examples 1-3 of the present invention;

[0028] Figure 4 It is a graph of the adsorption retention rate results of Examples 1-4 and Comparative Examples 1-3 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to the described content can be applied to the present invention. The preferred implementation methods and materials described herein are only for illustrative purposes and cannot limit the content of this application.

[0031] In the experimental methods of the following examples, unless otherwise specified, they are all conventional methods; the test materials used in the following examples, unless otherwise specified, are all purchased from commercial channels.

[0032] The sources of the reagents used in the examples are as follows:

[0033] Bacillus subtilis, brand: Tanmo Quality Inspection, product number: BHCC100903;

[0034] Sporobolomyces salmonicolor, brand: Tanmo Quality Inspection, product number: BHCC104355.

[0035] Example 1

[0036] This example presents a titanium-loaded microbial solidified particle water treatment agent, which includes the following components in parts by weight: 60 parts of a citric acid and titanium dioxide dual-modified adsorbent, 30 parts of a magnetic exfoliated bentonite-based aerogel material, 2 parts of Bacillus subtilis, and 2 parts of Sporobolomyces salmonicolor.

[0037] The citric acid and titanium dioxide dual-modified adsorbent includes the following components in parts by weight: 40 parts of sea urchin-shaped magnetic composite nanoparticles, 20 parts of citric acid, and 10 parts of nano-titanium dioxide.

[0038] The magnetic exfoliated bentonite-based aerogel material includes the following components in parts by weight: 8 parts of magnetic exfoliated bentonite, 10 parts of carboxylated cellulose nanofibers, and 3 parts of polyethyleneimine.

[0039] The preparation method of the citric acid and titanium dioxide dual-modified adsorbent specifically includes the following steps:

[0040] (1) Dissolve 3.5 g of ferric chloride hexahydrate in 40 mL of ethylene glycol, add 3.7 g of anhydrous sodium acetate under a stirring speed of 2000 rpm until completely dissolved, then transfer it to a 50 mL polytetrafluoroethylene liner, seal it and place it in a reaction kettle, keep it at 200 °C for 12 h, collect the precipitate by magnetic separation, wash it with deionized water and absolute ethanol, and then vacuum dry it at 60 °C. The magnetic Fe 3 O 4 microspheres are obtained by hydrothermal synthesis method. The surface of the microspheres is rich in active sites, which can adsorb heavy metal ions and pollutants through electrostatic interaction or coordination bonds, can generate hydroxyl radicals through chemical catalytic action to degrade antibiotics and other refractory organic substances, and can also reduce highly toxic pollutants to low-toxicity forms for subsequent degradation treatment, obtaining Fe 3 O 4 microspheres;

[0041] (2) The Fe 3 O 4The microspheres were dispersed in a mixed solution of 30 mL of absolute ethanol and 3 mL of water, sonicated for 5 min, then 1 mL of ammonia water, 10 mL of absolute ethanol and 0.5 mL of tetraethyl orthosilicate were added successively, sonicated at 30 °C for 3 h, the precipitate was collected by magnetic separation, washed with deionized water and absolute ethanol, and then vacuum dried at 60 °C. Silica was coated on the surface of Fe 3 O 4 microspheres. The introduction of silanol groups enhanced the adsorption capacity for heavy metal ions and organic pollutants. The silica coating layer not only prevented the aggregation between Fe 3 O 4 microspheres, could expose more active sites, improve the adsorption efficiency, but also broaden the pH range of use. Even in an acidic environment, it prevented the oxidation or dissolution of Fe 3 O 4 , improved the stability and recyclability of the material, and obtained modified Fe 3 O 4 microspheres;

[0042] (3) Sodium aluminate powder was added to 30 mL of water and stirred until dissolved. The addition amount of sodium aluminate was 0.2 g. Sodium aluminate released aluminate ions in water, serving as the key aluminum source for the synthesis of boehmite. The alkaline environment of sodium aluminate could reduce the formation of amorphous aluminum hydroxide or gibbsite, thus selectively guiding the formation of boehmite. 0.5 g of urea was added and stirred for 1 h, then the modified Fe 3 O 4 microspheres described in step (2) were added, sonicated for 2 h, then transferred to a reaction kettle, reacted at 180 °C for 6 h, the product was collected by magnetic separation, washed 5 times with deionized water, and then vacuum dried at 50 °C. The addition of urea would make more hydroxides in the solution, thus increasing the concentration of OH - , promoting the formation of layered or fibrous crystals. When OH - and AL 3+ were supersaturated in the solution, the formed boehmite grew densely on the surface of the modified Fe 3 O 4 microspheres, presenting a hierarchical sea urchin-like core-shell structure. Its porous network was beneficial to the adsorption of heavy metals, organic pollutants in water and the immobilization of microorganisms. Among them, boehmite could provide attachment sites for microorganisms, form a local microenvironment, reduce the impact of acids and bases on microorganisms, and the surface hydroxyl groups formed hydrogen bonds or coordination bonds with the extracellular polymers of microorganisms, enhancing the immobilization effect of microorganisms. At the same time, boehmite could wrap the microbial cells to form an isolation layer, hindering the penetration of H + and OH - , reducing the damage of the acid-base environment to microorganisms, enhancing the colonization density and activity of microorganisms, and obtaining sea urchin-like magnetic composite nanoparticles;

[0043] (4) Dissolve 2.0 g of citric acid in 100 mL of water to form a citric acid solution for standby use. Disperse the sea urchin-shaped magnetic composite nanoparticles described in step (3) in 40 mL of dimethyl sulfoxide and stir at 200 rpm for 12 h. Then add 6 mL of tetraethyl orthosilicate and continue stirring for 5 h. Then add 1.0 g of nano-titanium dioxide. The nano-titanium dioxide is rutile and has a particle size of 300 nm. It exhibits low photocatalytic activity and avoids the production of harmful intermediates. It also has good chemical stability and remains stable in strong acids and strong bases. Stir for 12 h and centrifuge. Wash the precipitate twice with distilled water, dry it in vacuum and immerse it in a citric acid solution. Stir in a nitrogen atmosphere at 2 00rpm stirring for 24h, and then vacuum drying. The chelating effect of citric acid can partially dissolve the amorphous region of boehmite, and form a richer mesoporous structure with nano-titanium dioxide. After nano-titanium dioxide doping and citric acid acidification, not only the porosity and adsorption sites of sea urchin-shaped magnetic composite nanoparticles are increased, thereby improving the adsorption capacity of heavy metal ions and organic pollutants, but also the physical embedding efficiency of microorganisms can be improved, which is beneficial to the loading stability of microorganisms. Among them, citric acid can promote the uniform dispersion of nano-titanium dioxide, and the high hardness of nano-titanium dioxide enhances the mechanical strength of the composite material and reduces the structural collapse during recycling, thus obtaining a citric acid and titanium dioxide dual modified adsorbent.

[0044] This embodiment provides a method for preparing a titanium-carrying microbial solidified granular water treatment agent, which specifically comprises the following steps:

[0045] S1. Add 10.0 g of bentonite to a mixed solution of 500 mL of ultrapure water and anhydrous ethanol, with a volume ratio of ultrapure water to anhydrous ethanol of 1:2.5, and stir evenly. First, stir the mixed solution in a microwave at 800 W and 60 ° C for 2 h, then subject it to ultrasonic dispersion treatment at 700 W for 2 h, and then vacuum dry it at 60 ° C for 12 h to obtain a peeled bentonite sheet for standby use. Add 1.8 g of ferric chloride and 0.6 g of ferric chloride to 100 mL of water and sieve it at 600 W and 60 ° C. After 5 minutes of pre-reaction, 10.5 mL of ammonia water was added, and stirring continued at 600 W and 60 ° C for 1 hour. Then, the stripped bentonite flakes were added and stirred for 2 hours. After cooling to room temperature, the product was collected by magnetic separation and washed with anhydrous ethanol and ultrapure water for several times until the pH reached 7.0. Finally, it was vacuum dried and ground. The stripped bentonite has a larger specific surface area, and its layered structure exposes more active sites, which can adsorb and accommodate more pollutants. At the same time, combined with the magnetic component Fe 3 O 4 The catalytic effect further promotes the decomposition of pollutants to obtain magnetic exfoliation bentonite;

[0046] S2. Add 1.0 g of carboxylated cellulose nanofibers to 100 mL of ultrapure water and stir magnetically to form a carboxylated cellulose nanofiber suspension. The diameter of the carboxylated cellulose nanofibers is 10 nm and the length is 3 μm. Carboxylated cellulose nanofibers with a suitable diameter have a higher adsorption capacity, and micron-sized fibers are more likely to form an intertwined porous network, enhancing mechanical strength and elasticity, which is suitable for dynamic adsorption in water. Then add a 50% by mass polyethyleneimine solution and the magnetic exfoliated bentonite described in step S1. The addition amount of the polyethyleneimine solution is 0.3 g. Polyethyleneimine is rich in amino groups and can bind to heavy metal ions such as Pb 2+ 、Cd 2+ 、Hg 2+ etc. through coordination, electrostatic attraction or ion exchange, and can also adsorb organic pollutants such as phenols and antibiotics, and can act as a cross-linking agent, which not only increases the specific surface area and porosity of the aerogel, improves the adsorption capacity, but also improves the mechanical strength of the aerogel and enhances the structural stability of the aerogel in water. Stir at 70 °C for 4 h with a stirring speed of 300 rpm. Through this process, a uniform network-like porous structure with slight wrinkles is formed, which can increase the adsorption performance for heavy metal ions and organic pollutants. The network structure effectively protects the stability of the magnetic component Fe 3 O 4 . Therefore, it can be used as a stable and reusable adsorbent material in the field of water treatment to obtain a magnetic exfoliated bentonite-based aerogel material;

[0047] S3. Inoculate 2.0 g of Bacillus subtilis and 2.0 g of Torulaspora delbrueckii into the MSM basal salt medium, add glucose with a concentration of 1% and glycerol with a concentration of 0.5% during the period, and control the pH to 7.0. Cultivate at 30 °C and 200 rpm until the viable cell concentration reaches 10 8 cfu / g to obtain a bacterial solution. Centrifuge, discard the supernatant, and collect the active bacteria. Then soak the citric acid and titanium dioxide dual-modified adsorbent in the MSM basal salt medium for 8 h, take it out and mix it with the active bacteria, and freeze-dry. Using the citric acid and titanium dioxide dual-modified adsorbent as a carrier, the active bacteria form a biofilm or are directly adsorbed on the carrier, enhancing the stability of the bacteria in water, reducing the adverse effects of the acid-base environment on the bacterial activity, ensuring a relatively high activity of the bacteria, and facilitating the purification of water by Bacillus subtilis combined with Torulaspora delbrueckii to obtain titanium-loaded microbial solidified particles;

[0048] S4. Add the titanium-loaded microbial solidified particles described in step S3 to the magnetic exfoliated bentonite-based aerogel material described in step S2, then perform ultrasonic dispersion treatment for 1 h, and then freeze-dry. The titanium-loaded microbial solidified particles form mechanical interlocks with the network structure of the magnetic exfoliated bentonite-based aerogel material in a sea urchin shape, increasing the structural stability, reducing the risk of aerogel collapse, broadening the pH range of use of the aerogel material, facilitating the stability of recycling, where the magnetic porous network enhances the adsorption stability of microorganisms, further protecting the activity of microorganisms. At the same time, the magnetic function enhances the adsorption performance of the composite material for pollutants. Combining with the decomposition of microorganisms, an efficient water purification effect is achieved, and a titanium-loaded microbial solidified particle water treatment agent is obtained.

[0049] In this example, a scanning electron microscope was used for the prepared titanium-loaded microbial solidified particle water treatment agent to observe its microscopic morphology. Figure 1 It is a SEM image of the titanium-loaded microbial solidified particle water treatment agent prepared in Example 1 magnified 100 times, as Figure 1 , the titanium-loaded microbial solidified particle water treatment agent prepared in this example presents a tightly combined and stable and rich pore structure.

[0050] Example 2

[0051] This example proposes a titanium-loaded microbial solidified particle water treatment agent, which includes the following components in parts by weight: 50 parts of a citric acid and titanium dioxide dual-modified adsorbent, 20 parts of a magnetic exfoliated bentonite-based aerogel material, 1 part of Bacillus subtilis, and 1 part of Saccharomyces kluyveri.

[0052] The citric acid and titanium dioxide dual-modified adsorbent includes the following components in parts by weight: 30 parts of sea urchin-shaped magnetic composite nanoparticles, 10 parts of citric acid, and 6 parts of nano-titanium dioxide.

[0053] The magnetic exfoliated bentonite-based aerogel material includes the following components in parts by weight: 5 parts of magnetic exfoliated bentonite, 8 parts of carboxylated cellulose nanofibers, and 1 part of polyethyleneimine.

[0054] The preparation method of the citric acid and titanium dioxide dual-modified adsorbent specifically includes the following steps:

[0055] (1) Dissolve 3.5 g of ferric chloride hexahydrate in 40 mL of ethylene glycol, add 3.7 g of anhydrous sodium acetate at a stirring speed of 1000 rpm until completely dissolved, then transfer it to a 50 mL polytetrafluoroethylene inner liner, seal it and put it into a reaction kettle, keep it warm at 180 °C for 10 h, collect the precipitate by magnetic separation, wash it with deionized water and absolute ethanol, and then vacuum dry it at 60 °C. The magnetic Fe 3 O 4Microspheres, which are rich in active sites on their surfaces, can adsorb heavy metal ions and pollutants through electrostatic interactions or coordination bonds, can generate hydroxyl radicals through chemical catalytic action to degrade refractory organic compounds such as antibiotics, and can also reduce highly toxic pollutants to low-toxicity forms for subsequent degradation treatment, obtaining Fe 3 O 4 microspheres;

[0056] (2)Disperse the Fe 3 O 4 microspheres described in step (1) in a mixed solution of 30 mL of absolute ethanol and 3 mL of water, ultrasonicate for 3 min, then successively add 1 mL of ammonia water, 10 mL of absolute ethanol and 0.3 mL of tetraethyl orthosilicate, ultrasonicate at 20 °C for 2 h, collect the precipitate by magnetic separation, wash with deionized water and absolute ethanol, and then vacuum dry at 60 °C. The silica is coated on the surface of the Fe 3 O 4 microspheres. The introduction of silanol groups enhances the adsorption capacity for heavy metal ions and organic pollutants. The silica coating layer can not only prevent the aggregation of Fe 3 O 4 microspheres, expose more active sites, improve the adsorption efficiency, but also broaden the pH range of use. Even in an acidic environment, it prevents the oxidation or dissolution of Fe 3 O 4 , improve the stability and recyclability of the material, obtaining modified Fe 3 O 4 microspheres;

[0057] (3)Add sodium aluminate powder to 30 mL of water and stir until dissolved. The addition amount of sodium aluminate is 0.1 g. Sodium aluminate releases aluminate ions in water, serving as the key aluminum source for the synthesis of boehmite. The alkaline environment of sodium aluminate can reduce the formation of amorphous aluminum hydroxide or gibbsite, thereby selectively guiding the formation of boehmite. Add 0.3 g of urea and stir for 0.5 h. Then add the modified Fe 3 O 4 microspheres described in step (2), ultrasonicate for 1 h, then transfer to a reaction kettle and react at 160 °C for 5 h. Collect the product by magnetic separation, wash 3 times with deionized water, and then vacuum dry at 50 °C. The addition of urea will increase the amount of hydroxides in the solution, thereby increasing the concentration of OH - , promoting the formation of layered or fibrous crystals. When the OH - and AL 3+ in the solution are supersaturated, the formed boehmite grows densely on the modified Fe 3 O 4On the surface of the microspheres, a hierarchical sea urchin-like core-shell structure is presented. Its porous network is beneficial for adsorbing heavy metals, organic pollutants in water bodies, and immobilizing microorganisms. Among them, boehmite can provide attachment sites for microorganisms, form a local microenvironment, reduce the impact of acids and bases on microorganisms. The surface hydroxyl groups form hydrogen bonds or coordination bonds with the extracellular polymers of microorganisms, enhancing the immobilization effect of microorganisms. At the same time, boehmite can wrap the microbial cells to form an isolation layer, hindering the penetration of H + and OH - , reducing the damage of the acid-base environment to microorganisms, enhancing the colonization density and activity of microorganisms, and obtaining sea urchin-like magnetic composite nanoparticles;

[0058] (4) Dissolve 1.0 g of citric acid in 100 mL of water to form a citric acid solution for later use. Disperse the sea urchin-like magnetic composite nanoparticles described in step (3) in 40 mL of dimethyl sulfoxide, stir at a speed of 100 rpm for 12 h, then add 6 mL of tetraethyl orthosilicate, continue stirring for 3 h, and then add 0.6 g of titanium dioxide nanoparticles. The titanium dioxide nanoparticles are of the rutile type with a particle size of 100 nm, showing low photocatalytic activity, avoiding the generation of harmful intermediate products, and also having good chemical stability, remaining stable in strong acids and strong bases. Stir for 8 h, centrifuge, wash the precipitate with distilled water twice, vacuum dry, immerse it in the citric acid solution, stir at a speed of 100 rpm in a nitrogen atmosphere for 24 h, and then vacuum dry. The chelating effect of citric acid can partially dissolve the amorphous region of boehmite and form a richer mesoporous structure in combination with titanium dioxide nanoparticles. After doping with titanium dioxide nanoparticles and acidifying with citric acid, not only the porosity and adsorption sites of the sea urchin-like magnetic composite nanoparticles are increased, thereby enhancing the adsorption capacity for heavy metal ions and organic pollutants, but also the physical embedding efficiency of microorganisms is improved, which is beneficial to the load stability of microorganisms. Among them, citric acid can promote the uniform dispersion of titanium dioxide nanoparticles, and the high hardness of titanium dioxide nanoparticles enhances the mechanical strength of the composite material, reducing the structural collapse during repeated use, and obtaining a double-modified adsorbent of citric acid and titanium dioxide.

[0059] This example provides a preparation method of a titanium-loaded microbial solidified particle water treatment agent, which specifically includes the following steps:

[0060] S1. Add 10.0 g of bentonite into a mixed solution of 500 mL of ultrapure water and absolute ethanol with a volume ratio of ultrapure water to absolute ethanol being 1:2.5. Stir evenly. First, microwave and stir the mixed solution at 600 W and 60 °C for 1 h, then perform ultrasonic dispersion treatment at a power of 600 W for 1 h, and then vacuum dry at 60 °C for 12 h to obtain exfoliated bentonite sheets for use. Add 1.0 g of ferric chloride and 0.6 g of ferrous chloride into 100 mL of water, pre-react at 500 W and 60 °C for 3 min, then add 10.5 mL of ammonia water, continue to stir at 500 W and 60 °C for 0.5 h, and then add the exfoliated bentonite sheets into it. Stir thoroughly for 1 h. After cooling to room temperature, collect the product by magnetic separation, and wash it with absolute ethanol and ultrapure water multiple times until the pH reaches 7.0. Finally, vacuum dry and grind. The exfoliated bentonite has a large specific surface area, and its layered structure exposes more active sites, which can adsorb and accommodate more pollutants. At the same time, combined with the catalytic effect of the magnetic component Fe 3 O 4 , it further promotes the decomposition of pollutants to obtain magnetic exfoliated bentonite;

[0061] S2. Add 0.8 g of carboxylated cellulose nanofibers into 100 mL of ultrapure water, and magnetically stir to form a carboxylated cellulose nanofiber suspension. The diameter of the carboxylated cellulose nanofibers is 4 nm and the length is 1 μm. Carboxylated cellulose nanofibers with a suitable diameter have a higher adsorption capacity, and micron-scale fibers are more likely to form an intertwined porous network, improving mechanical strength and elasticity, which is suitable for dynamic adsorption in water bodies. Then add a 50% polyethyleneimine solution and the magnetic exfoliated bentonite described in step S1. The addition amount of the polyethyleneimine solution is 0.1 g. Polyethyleneimine is rich in amino groups and can combine with heavy metal ions such as Pb 2+ , Cd 2+ , Hg 2+ etc. through coordination, electrostatic attraction or ion exchange, and can also adsorb organic pollutants such as phenols and antibiotics, and can act as a cross-linking agent, which not only increases the specific surface area and porosity of the aerogel, improves the adsorption capacity, but also improves the mechanical strength of the aerogel and enhances the structural stability of the aerogel in water bodies. Stir at 60 °C for 3 h with a stirring speed of 200 rpm. Through this process, a uniform network-like porous structure with slight wrinkles is formed, which can increase the adsorption performance for heavy metal ions and organic pollutants. Among them, the network structure effectively protects the stability of the magnetic component Fe 3 O 4 . Therefore, it can be used as a stable and reusable adsorption material in the field of water treatment to obtain a magnetic exfoliated bentonite-based aerogel material;

[0062] S3. Inoculate 1.0 g of *Bacillus subtilis* and 1.0 g of *Sporidiobolus salmonicolor* into the MSM basal salt medium, add glucose with a concentration of 1% and glycerol with a concentration of 0.5% during the process, and at the same time control the pH to 6.5. Cultivate at 28 °C and 150 rpm until the viable cell concentration reaches 10 8 cfu / g to obtain a bacterial solution. Centrifuge the bacterial solution, discard the supernatant, collect the active bacteria, and then soak the adsorbent modified by both citric acid and titanium dioxide in the MSM basal salt medium for 6 h. After taking it out, mix it with the active bacteria and freeze-dry it. With the adsorbent modified by both citric acid and titanium dioxide as the carrier, the active bacteria form a biofilm or are directly adsorbed on the carrier, enhancing the stability of the bacteria in the water body, reducing the adverse effects of the acid-base environment on the activity of the bacteria, ensuring a relatively high activity of the bacteria, and being conducive to exerting the purification effect of *Bacillus subtilis* combined with *Sporidiobolus salmonicolor* on the water body, thus obtaining the titanium-loaded microbial solidified particles;

[0063] S4. Add the titanium-loaded microbial solidified particles described in step S3 into the magnetic exfoliated bentonite-based aerogel material described in step S2, then perform ultrasonic dispersion treatment for 0.5 h, and then freeze-dry it. The titanium-loaded microbial solidified particles form mechanical interlocks with the network structure of the magnetic exfoliated bentonite-based aerogel material in a sea urchin shape, increasing the structural stability, reducing the risk of aerogel collapse, broadening the pH usage range of the aerogel material, and being conducive to the stability of recycling. Among them, the magnetic porous network enhances the adsorption stability of the microorganisms, further protecting the activity of the microorganisms. At the same time, the magnetic function enhances the adsorption performance of the composite material for pollutants. Combining with the decomposition effect of the microorganisms, an efficient water purification effect is achieved, and a water treatment agent of titanium-loaded microbial solidified particles is obtained.

[0064] Example 3

[0065] This example provides a water treatment agent of titanium-loaded microbial solidified particles, which comprises the following components in parts by weight: 55 parts of an adsorbent modified by both citric acid and titanium dioxide, 25 parts of a magnetic exfoliated bentonite-based aerogel material, 1.5 parts of *Bacillus subtilis*, and 1.5 parts of *Sporidiobolus salmonicolor*.

[0066] The adsorbent modified by both citric acid and titanium dioxide comprises the following components in parts by weight: 35 parts of sea urchin-shaped magnetic composite nanoparticles, 15 parts of citric acid, and 8 parts of nano-titanium dioxide.

[0067] The magnetic exfoliated bentonite-based aerogel material comprises the following components in parts by weight: 6.5 parts of magnetic exfoliated bentonite, 9 parts of carboxylated cellulose nanofibers, and 2 parts of polyethyleneimine.

[0068] The preparation method of the adsorbent modified by both citric acid and titanium dioxide specifically comprises the following steps:

[0069] (1) Dissolve 3.5 g of ferric chloride hexahydrate in 40 mL of ethylene glycol. Add 3.7 g of anhydrous sodium acetate under a stirring speed of 1500 rpm until completely dissolved. Then transfer it to a 50 mL polytetrafluoroethylene liner, seal it, and place it in a reaction kettle. Keep it at 190 °C for 11 h. Collect the precipitate by magnetic separation, wash it with deionized water and absolute ethanol, and then vacuum dry it at 60 °C. The magnetic Fe 3 O 4 microspheres are obtained. Their surfaces are rich in active sites, which can adsorb heavy metal ions and pollutants through electrostatic interactions or coordination bonds, can generate hydroxyl radicals through chemical catalysis to degrade refractory organic compounds such as antibiotics, and can also reduce highly toxic pollutants to low-toxicity forms for subsequent degradation treatment, obtaining Fe 3 O 4 microspheres;

[0070] (2) Disperse the Fe 3 O 4 microspheres obtained in step (1) in a mixed solution of 30 mL of absolute ethanol and 3 mL of water, sonicate for 4 min, then sequentially add 1 mL of ammonia water, 10 mL of absolute ethanol, and 0.4 mL of tetraethyl orthosilicate, and sonicate at 25 °C for 2.5 h. Collect the precipitate by magnetic separation, wash it with deionized water and absolute ethanol, and then vacuum dry it at 60 °C. The silica is coated on the surface of the Fe 3 O 4 microspheres. The introduction of silanol groups enhances the adsorption capacity for heavy metal ions and organic pollutants. The silica coating layer can not only prevent the aggregation of Fe 3 O 4 microspheres, expose more active sites to improve the adsorption efficiency, but also broaden the pH range of use. Even in an acidic environment, it can prevent the oxidation or dissolution of Fe 3 O 4 , improve the stability and recyclability of the material, and obtain modified Fe 3 O 4 microspheres;

[0071] (3) Add sodium aluminate powder to 30 mL of water and stir until dissolved. The addition amount of sodium aluminate is 0.15 g. Sodium aluminate releases aluminate ions in water, which serves as the key aluminum source for the synthesis of boehmite. The alkaline environment of sodium aluminate can reduce the formation of amorphous aluminum hydroxide or gibbsite, thus selectively guiding the formation of boehmite. Add 0.4 g of urea and stir for 0.75 h. Then add the modified Fe 3 O 4The microspheres were ultrasonically treated for 1.5 h, then transferred to a reaction kettle and reacted at 170 °C for 5.5 h. The product was collected by magnetic separation, washed 4 times with deionized water, and then vacuum dried at 50 °C. The addition of urea increased the amount of hydroxide in the solution, thus increasing the concentration of OH - and promoted the formation of layered or fibrous crystals. When OH - and AL 3+ were supersaturated in the solution, the formed boehmite grew densely on the surface of the modified Fe 3 O 4 microspheres, presenting a hierarchical sea urchin-like core-shell structure. Its porous network is beneficial for the adsorption of heavy metals, organic pollutants in water and the immobilization of microorganisms. Among them, boehmite can provide attachment sites for microorganisms, form a local microenvironment, reduce the impact of acid-base on microorganisms, and the surface hydroxyl groups form hydrogen bonds or coordination bonds with the extracellular polymers of microorganisms, enhancing the immobilization effect of microorganisms. At the same time, boehmite can wrap the microbial cells to form an isolation layer, hindering the penetration of H + and OH - , reducing the damage of the acid-base environment to microorganisms, and enhancing the colonization density and activity of microorganisms, obtaining sea urchin-like magnetic composite nanoparticles;

[0072] (4) Dissolve 1.5 g of citric acid in 100 mL of water to form a citric acid solution for use. Disperse the sea urchin-like magnetic composite nanoparticles described in step (3) in 40 mL of dimethyl sulfoxide, stir at a speed of 150 rpm for 12 h, then add 6 mL of tetraethyl orthosilicate, continue to stir for 4 h, and then add 0.8 g of titanium dioxide nanoparticles. The titanium dioxide nanoparticles are of the rutile type with a particle size of 200 nm, showing low photocatalytic activity, avoiding the generation of harmful intermediate products, and also having good chemical stability, remaining stable in strong acids and strong alkalis. Stir for 10 h, centrifuge, wash the precipitate 2 times with distilled water, vacuum dry and then immerse it in the citric acid solution, stir at a speed of 150 rpm in a nitrogen atmosphere for 24 h, and then vacuum dry. The chelating effect of citric acid can partially dissolve the amorphous region of boehmite and form a more abundant mesoporous structure in combination with titanium dioxide nanoparticles. After doping with titanium dioxide nanoparticles and acidifying with citric acid, not only the porosity and adsorption sites of the sea urchin-like magnetic composite nanoparticles are increased, thus enhancing the adsorption capacity for heavy metal ions and organic pollutants, but also the physical embedding efficiency of microorganisms is improved, which is beneficial to the load stability of microorganisms. Among them, citric acid can promote the uniform dispersion of titanium dioxide nanoparticles, and the high hardness of titanium dioxide nanoparticles enhances the mechanical strength of the composite material, reducing the structural collapse during repeated use, obtaining a double-modified adsorbent of citric acid and titanium dioxide.

[0073] This example provides a preparation method of a titanium-loaded microbial immobilized particle water treatment agent, which specifically includes the following steps:

[0074] S1. Add 10.0 g of bentonite into a mixed solution of 500 mL of ultrapure water and absolute ethanol, with the volume ratio of ultrapure water to absolute ethanol being 1:2.5. Stir evenly. First, microwave and stir the mixed solution at 700 W and 60 °C for 1.5 h, then perform ultrasonic dispersion treatment at a power of 650 W for 1.5 h, and then vacuum dry at 60 °C for 12 h to obtain exfoliated bentonite sheets for use. Add 1.4 g of ferric chloride and 0.6 g of ferrous chloride into 100 mL of water, pre-react at 550 W and 60 °C for 4 min, then add 10.5 mL of ammonia water, continue to stir at 550 W and 60 °C for 0.75 h, and then add the exfoliated bentonite sheets into it, stir thoroughly for 1.5 h. After cooling to room temperature, collect the product by magnetic separation, and wash it with absolute ethanol and ultrapure water for multiple times until the pH reaches 7.0. Finally, vacuum dry and grind. The exfoliated bentonite has a large specific surface area, and its layered structure exposes more active sites, which can adsorb and accommodate more pollutants. At the same time, combined with the catalytic action of the magnetic component Fe 3 O 4 , it further promotes the decomposition of pollutants to obtain magnetic exfoliated bentonite;

[0075] S2. Add 0.9 g of carboxylated cellulose nanofibers into 100 mL of ultrapure water, and stir magnetically to form a carboxylated cellulose nanofiber suspension. The diameter of the carboxylated cellulose nanofibers is 7 nm and the length is 2 μm. Carboxylated cellulose nanofibers with an appropriate diameter have a higher adsorption capacity, and micron-scale fibers are more likely to form an intertwined porous network, improving mechanical strength and elasticity, and are suitable for dynamic adsorption in water bodies. Then add a 50% polyethyleneimine solution by mass and the magnetic exfoliated bentonite described in step S1. The addition amount of the polyethyleneimine solution is 0.2 g. Polyethyleneimine is rich in amino groups and can bind to heavy metal ions such as Pb 2+ , Cd 2+ , Hg 2+ etc. through coordination, electrostatic attraction or ion exchange, and can also adsorb organic pollutants such as phenols and antibiotics, and can act as a cross-linking agent, which not only increases the specific surface area and porosity of the aerogel, improves the adsorption capacity, but also improves the mechanical strength of the aerogel and enhances the structural stability of the aerogel in water bodies. Stir at 65 °C for 3.5 h with a stirring speed of 250 rpm. Through this process, a uniform network-like porous structure with slight wrinkles is formed, which can increase the adsorption performance for heavy metal ions and organic pollutants. Among them, the network structure effectively protects the stability of the magnetic component Fe 3 O 4 . Therefore, it can be used as a stable and reusable adsorption material in the field of water treatment to obtain a magnetic exfoliated bentonite-based aerogel material;

[0076] S3. Inoculate 1.5 g of *Bacillus subtilis* and 1.5 g of *Sporidiobolus salmonicolor* into the MSM basal salt medium. During this period, add glucose with a concentration of 1% and glycerol with a concentration of 0.5%, and at the same time control the pH to 6.8. Cultivate at 28 °C and 175 rpm until the viable cell concentration reaches 10 8 cfu / g to obtain a bacterial solution. Centrifuge the bacterial solution, discard the supernatant, collect the active bacteria, and then soak the dual-modified adsorbent of citric acid and titanium dioxide in the MSM basal salt medium for 7 h. After taking it out, mix it with the active bacteria and freeze-dry it. With the dual-modified adsorbent of citric acid and titanium dioxide as the carrier, the active bacteria form a biofilm or are directly adsorbed on the carrier, enhancing the stability of the bacteria in the water body, reducing the adverse effects of the acid-base environment on the bacterial activity, ensuring a relatively high activity of the bacteria, and being beneficial to exerting the purification effect of the combination of *Bacillus subtilis* and *Sporidiobolus salmonicolor* on the water body, obtaining the titanium-loaded microbial solidified particles;

[0077] S4. Add the titanium-loaded microbial solidified particles described in step S3 into the magnetic exfoliated bentonite-based aerogel material described in step S2, and then perform ultrasonic dispersion treatment for 0.75 h, and then freeze-dry it. The titanium-loaded microbial solidified particles form mechanical interlocks with the network structure of the magnetic exfoliated bentonite-based aerogel material in a sea urchin shape, increasing the structural stability, reducing the risk of aerogel collapse, broadening the pH usage range of the aerogel material, and being beneficial to the stability of recycling. Among them, the magnetic porous network enhances the adsorption stability of the microorganisms, further protecting the activity of the microorganisms. At the same time, the magnetic function enhances the adsorption performance of the composite material for pollutants. Combining with the decomposition effect of the microorganisms, an efficient water purification effect is achieved, obtaining the titanium-loaded microbial solidified particle water treatment agent.

[0078] Example 4

[0079] This example proposes a titanium-loaded microbial solidified particle water treatment agent, which includes the following components in parts by weight: 60 parts of the dual-modified adsorbent of citric acid and titanium dioxide, 20 parts of the magnetic exfoliated bentonite-based aerogel material, 2 parts of *Bacillus subtilis*, and 1 part of *Sporidiobolus salmonicolor*.

[0080] The dual-modified adsorbent of citric acid and titanium dioxide includes the following components in parts by weight: 40 parts of sea urchin-shaped magnetic composite nanoparticles, 10 parts of citric acid, and 10 parts of nano-titanium dioxide.

[0081] The magnetic exfoliated bentonite-based aerogel material includes the following components in parts by weight: 8 parts of magnetic exfoliated bentonite, 10 parts of carboxylated cellulose nanofibers, and 1 part of polyethyleneimine.

[0082] The preparation method of the dual-modified adsorbent of citric acid and titanium dioxide specifically includes the following steps:

[0083] (1) Dissolve 3.5 g of ferric chloride hexahydrate in 40 mL of ethylene glycol. Add 3.7 g of anhydrous sodium acetate under stirring at 2000 rpm until completely dissolved. Then transfer it to a 50 mL polytetrafluoroethylene liner, seal it and place it in a reaction kettle. Keep it at 200 °C for 10 h. Collect the precipitate by magnetic separation, wash it with deionized water and absolute ethanol, and then dry it in vacuum at 60 °C. The magnetic Fe 3 O 4 microspheres are obtained. Their surfaces are rich in active sites, which can adsorb heavy metal ions and pollutants through electrostatic interaction or coordination bonds, can generate hydroxyl radicals through chemical catalytic action to degrade refractory organic substances such as antibiotics, and can also reduce highly toxic pollutants to low-toxicity forms for subsequent degradation treatment, obtaining Fe 3 O 4 microspheres;

[0084] (2) Disperse the Fe 3 O 4 microspheres obtained in step (1) in a mixed solution of 30 mL of absolute ethanol and 3 mL of water, ultrasonicate for 3 min, then sequentially add 1 mL of ammonia water, 10 mL of absolute ethanol and 0.5 mL of tetraethyl orthosilicate, ultrasonicate at 30 °C for 2 h, collect the precipitate by magnetic separation, wash it with deionized water and absolute ethanol, and then dry it in vacuum at 60 °C. The silica is coated on the surface of the Fe 3 O 4 microspheres. The introduction of silanol groups enhances the adsorption capacity for heavy metal ions and organic pollutants. The silica coating layer can not only prevent the aggregation between Fe 3 O 4 microspheres, can expose more active sites to improve the adsorption efficiency, but also broaden the pH range of use. Even in an acidic environment, it can prevent the oxidation or dissolution of Fe 3 O 4 , improve the stability and recyclability of the material, and obtain modified Fe 3 O 4 microspheres;

[0085] (3) Add sodium aluminate powder to 30 mL of water and stir until dissolved. The addition amount of sodium aluminate is 0.2 g. Sodium aluminate releases aluminate ions in water, which is the key aluminum source for the synthesis of boehmite. The alkaline environment of sodium aluminate can reduce the formation of amorphous aluminum hydroxide or gibbsite, thus selectively guiding the formation of boehmite. Add 0.3 g of urea and stir for 0.5 h. Then add the modified Fe 3 O 4The microspheres were ultrasonically treated for 1 h, then transferred to a reaction kettle and reacted at 180 °C for 5 h. The product was collected by magnetic separation, washed 5 times with deionized water, and then vacuum dried at 50 °C. The addition of urea increased the amount of hydroxides in the solution, thus increasing the concentration of OH - and promoting the formation of layered or fibrous crystals. When OH - and AL 3+ were supersaturated in the solution, the formed boehmite densely grew on the surface of the modified Fe 3 O 4 microspheres, presenting a hierarchical sea urchin-like core-shell structure. Its porous network is beneficial for adsorbing heavy metals, organic pollutants in water bodies and immobilizing microorganisms. Among them, boehmite can provide attachment sites for microorganisms, form a local microenvironment, reduce the impact of acids and bases on microorganisms, and the surface hydroxyl groups form hydrogen bonds or coordination bonds with the extracellular polymers of microorganisms, enhancing the immobilization effect of microorganisms. At the same time, boehmite can wrap the microbial cells to form an isolation layer, hindering the penetration of H + and OH - , reducing the damage of the acid-base environment to microorganisms, and enhancing the colonization density and activity of microorganisms, obtaining sea urchin-like magnetic composite nanoparticles;

[0086] (4) Dissolve 1.0 g of citric acid in 100 mL of water to form a citric acid solution for use. Disperse the sea urchin-like magnetic composite nanoparticles described in step (3) in 40 mL of dimethyl sulfoxide, stir at a speed of 200 rpm for 12 h, then add 6 mL of tetraethyl orthosilicate, continue to stir for 3 h, and then add 1.0 g of titanium dioxide nanoparticles. The titanium dioxide is of the rutile type with a particle size of 300 nm, showing low photocatalytic activity, avoiding the generation of harmful intermediate products, and also having good chemical stability, remaining stable in strong acids and strong bases. Stir for 8 h, centrifuge, wash the precipitate 2 times with distilled water, vacuum dry and then immerse it in the citric acid solution, stir at a speed of 200 rpm in a nitrogen atmosphere for 24 h, and then vacuum dry. The chelating effect of citric acid can partially dissolve the amorphous region of boehmite and form a more abundant mesoporous structure in combination with titanium dioxide nanoparticles. After doping with titanium dioxide nanoparticles and acidifying with citric acid, not only the porosity and adsorption sites of the sea urchin-like magnetic composite nanoparticles are increased, thus enhancing the adsorption capacity for heavy metal ions and organic pollutants, but also the physical embedding efficiency of microorganisms is improved, which is beneficial to the loading stability of microorganisms. Among them, citric acid can promote the uniform dispersion of titanium dioxide nanoparticles, and the high hardness of titanium dioxide nanoparticles enhances the mechanical strength of the composite material, reducing the structural collapse during repeated use, obtaining a double-modified adsorbent of citric acid and titanium dioxide.

[0087] This example provides a preparation method of a titanium-loaded microbial immobilized particle water treatment agent, which specifically includes the following steps:

[0088] S1. Add 10.0 g of bentonite into a mixed solution of 500 mL of ultrapure water and absolute ethanol, with the volume ratio of ultrapure water to absolute ethanol being 1:2.5. Stir evenly. First, microwave-stir the mixed solution at 800 W and 60 °C for 1 h, then perform ultrasonic dispersion treatment at a power of 700 W for 1 h, and then vacuum-dry at 60 °C for 12 h to obtain exfoliated bentonite sheets for use. Add 1.8 g of ferric chloride and 0.6 g of ferrous chloride into 100 mL of water, pre-react at 600 W and 60 °C for 3 min, then add 10.5 mL of ammonia water, continue to stir at 600 W and 60 °C for 0.5 h, and then add the exfoliated bentonite sheets into it. Stir thoroughly for 1 h. After cooling to room temperature, collect the product by magnetic separation, and wash it with absolute ethanol and ultrapure water for multiple times until the pH reaches 7.0. Finally, vacuum-dry and grind. The exfoliated bentonite has a large specific surface area, and its layered structure exposes more active sites, which can adsorb and accommodate more pollutants. At the same time, combined with the catalytic effect of the magnetic component Fe 3 O 4 , it further promotes the decomposition of pollutants to obtain magnetic exfoliated bentonite;

[0089] S2. Add 1.0 g of carboxylated cellulose nanofibers into 100 mL of ultrapure water, and magnetically stir to form a carboxylated cellulose nanofiber suspension. The diameter of the carboxylated cellulose nanofibers is 10 nm and the length is 1 μm. Carboxylated cellulose nanofibers with a suitable diameter size have a higher adsorption capacity, and micron-scale fibers are more likely to form an intertwined porous network, improving mechanical strength and elasticity, which is suitable for dynamic adsorption in water bodies. Then add a 50% polyethyleneimine solution by mass and the magnetic exfoliated bentonite described in step S1. The addition amount of the polyethyleneimine solution is 0.1 g. Polyethyleneimine is rich in amino groups and can bind to heavy metal ions such as Pb 2+ , Cd 2+ , Hg 2+ etc. through coordination, electrostatic attraction or ion exchange, and can also adsorb organic pollutants such as phenols and antibiotics, and can act as a cross-linking agent. It not only increases the specific surface area and porosity of the aerogel, improves the adsorption capacity, but also improves the mechanical strength of the aerogel and enhances the structural stability of the aerogel in water bodies. Stir at 70 °C for 3 h with a stirring speed of 300 rpm. Through this process, a uniform networked porous structure with slight wrinkles is formed, which can increase the adsorption performance for heavy metal ions and organic pollutants. Among them, the network structure effectively protects the stability of the magnetic component Fe 3 O 4 . Therefore, it can be used as a stable and reusable adsorption material in the field of water treatment to obtain a magnetic exfoliated bentonite-based aerogel material;

[0090] S3. Inoculate 2.0 g of Bacillus subtilis and 1.0 g of Saccharomyces sphaericus into the MSM basal salt medium, add glucose with a concentration of 1% and glycerol with a concentration of 0.5% during the process, and at the same time control the pH to 7.0. Cultivate at 30 °C and 200 rpm until the viable cell concentration reaches 10 8 cfu / g to obtain a bacterial solution. Centrifuge it, discard the supernatant, collect the active bacteria, and then soak the dual-modified adsorbent of citric acid and titanium dioxide in the MSM basal salt medium for 6 h. After taking it out, mix it with the active bacteria and freeze-dry it. Using the dual-modified adsorbent of citric acid and titanium dioxide as the carrier, the active bacteria form a biofilm or are directly adsorbed on the carrier, enhancing the stability of the bacteria in the water body, reducing the adverse effects of the acid-base environment on the bacterial activity, ensuring a relatively high activity of the bacteria, and being beneficial to exerting the purification effect of the combination of Bacillus subtilis and Saccharomyces sphaericus on the water body, thus obtaining the titanium-loaded microbial solidified particles;

[0091] S4. Add the titanium-loaded microbial solidified particles described in step S3 into the magnetic exfoliated bentonite-based aerogel material described in step S2, then perform ultrasonic dispersion treatment for 0.5 h, and then freeze-dry it. The titanium-loaded microbial solidified particles form mechanical interlocks with the network structure of the magnetic exfoliated bentonite-based aerogel material in a sea urchin shape, increasing the structural stability, reducing the risk of aerogel collapse, broadening the pH usage range of the aerogel material, and being beneficial to the stability of recycling. Among them, the magnetic porous network enhances the adsorption stability of the microorganisms, further protecting the activity of the microorganisms. At the same time, the magnetic function enhances the adsorption performance of the composite material for pollutants. Combining with the decomposition effect of the microorganisms, an efficient water purification effect is achieved, and a titanium-loaded microbial solidified particle water treatment agent is obtained.

[0092] Comparative Example 1

[0093] This comparative example provides a titanium-loaded microbial solidified particle water treatment agent, which is different from Example 1 in that the dual-modified adsorbent of citric acid and titanium dioxide does not contain boehmite; the preparation method of the dual-modified adsorbent of citric acid and titanium dioxide does not include step (3); the preparation method of the titanium-loaded microbial solidified particle water treatment agent is the same as that in Example 1.

[0094] Comparative Example 2

[0095] This comparative example provides a titanium-loaded microbial solidified particle water treatment agent, which is different from Example 1 in that the dual-modified adsorbent of citric acid and titanium dioxide does not contain citric acid and nano-titanium dioxide; the preparation method of the dual-modified adsorbent of citric acid and titanium dioxide does not include step (4); the preparation method of the titanium-loaded microbial solidified particle water treatment agent is the same as that in Example 1.

[0096] Comparative Example 3

[0097] This comparative example provides a titanium-loaded microbial solidified particle water treatment agent, which is different from Example 1 in that the magnetic exfoliated bentonite-based aerogel material does not contain magnetic exfoliated bentonite; the preparation method of the citric acid and titanium dioxide dual-modified adsorbent is the same as that in Example 1; the preparation method of the titanium-loaded microbial solidified particle water treatment agent does not include step S1.

[0098] Experimental Example 1

[0099] Bacterial activity experiment

[0100] Test samples: The titanium-loaded microbial solidified particle water treatment agents prepared in Examples 1-4 and Comparative Examples 1-3.

[0101] Test method: Weigh 0.5 g of the test sample to determine the viable bacteria count. Take 50 mL of the sample from the polluted water with a water body pH of 4.0. Add the test sample to 50 mL of the polluted water and shake and culture it at 37 °C and 120 rpm for 3 h. Pipette 0.5 mL of the sample solution, make gradient dilutions with PBS buffer solution, and determine the viable bacteria count. Calculate the bacterial survival rate. The higher the bacterial survival rate, the stronger the bacterial activity. The calculation formula for the bacterial survival rate is as follows:

[0102] Bacterial survival rate (%) = viable bacteria count after testing / viable bacteria count before testing × 100%

[0103] Figure 2 is the result graph of the bacterial survival rate of Examples 1-4 and Comparative Examples 1-3; as shown in the figure, the bacterial survival rates of Examples 1-4 are 90.5 - 93.2%, indicating strong bacterial activity; the bacterial survival rates of Comparative Examples 1-3 are 78.4 - 83.3%, indicating weak bacterial activity; the citric acid and titanium dioxide dual-modified adsorbent in Comparative Example 1 does not contain boehmite and cannot form a sea urchin-like structure, which is neither conducive to the attachment and solidification stability of microorganisms nor can it wrap microbial cells, and is not conducive to exerting the isolation layer's penetration and obstruction of H + and OH - , increasing the damage of the acid-base environment to microorganisms and resulting in weak bacterial activity; the citric acid and titanium dioxide dual-modified adsorbent in Comparative Example 2 does not contain citric acid and nano-titanium dioxide, and cannot increase the adsorption sites and chemical stability through doping and acidification modification, reducing the load quantity and load stability of microorganisms, and is not conducive to reducing the damage of the acid-base environment to microorganisms, resulting in weak bacterial activity; the magnetic exfoliated bentonite-based aerogel material in Comparative Example 3 does not contain magnetic exfoliated bentonite, which is not conducive to the formation of a slightly wrinkled magnetic porous network, is not conducive to the loading of titanium-loaded microbial solidified particles, and weakens the protection of microbial activity, resulting in weak bacterial activity.

[0104] Experimental Example 2

[0105] Adsorption experiment

[0106] Test samples: Titanium-loaded microbial solidified particulate water treatment agents prepared in Examples 1-4 and Comparative Examples 1-3.

[0107] Test method: Prepare simulated polluted water with an antibiotic mass concentration of 100 mg / L and a heavy metal concentration of 100 mg / L, and the pH of the water body is 4.0 - 4.5. In this experiment, common tetracycline is selected as the organic pollutant and Pb 2+ is used as the heavy metal pollutant for the adsorption experiment. Weigh 1.0 g of the test sample and add it to 1000 mL of simulated polluted water. Place it in a constant temperature oscillator (303 K, 120 rpm) and react for 24 h. Then filter it through a 0.45 μm organic filter membrane. The absorbance of tetracycline in the filtrate is measured by UV at 355 nm. According to the concentration-absorbance standard curve fitting equation y = 5.5728x - 0.0186 (R 2 = 0.99834) of tetracycline solutions with different mass concentrations, the mass concentration of tetracycline corresponding to the measured absorbance of the solution is obtained. Similarly, the absorbance of Pb 2+ is measured by ultraviolet spectrophotometry at 520 nm, and the adsorption amounts (mg / g) of tetracycline and Pb²⁺ are calculated according to the following formula:

[0108] Adsorption amount (mg / g) = (C 0 - C e ) × V / m

[0109] where C 0 is the initial pollutant mass concentration in mg / L, C e is the pollutant mass concentration after adsorption in mg / L, V is the solution volume in L, and m is the added amount of the test sample in g.

[0110] Figure 3 is the result graph of the pollutant adsorption amounts of Examples 1-4 and Comparative Examples 1-3; as shown in the figure, the adsorption amounts of tetracycline and Pb 2+ in Examples 1-4 are 80 - 89 mg / g and 71 - 76 mg / g, indicating good adsorption properties; the adsorption amounts of tetracycline and Pb 2+ in Comparative Examples 1-3 are 58 - 71 mg / g and 46 - 60 mg / g, indicating poor adsorption properties; the dual-modified adsorbent of citric acid and titanium dioxide in Comparative Example 1 does not contain boehmite and cannot modify Fe 3 O 4The formation of a hierarchical sea urchin-like structure on the surface of the microspheres is not conducive to increasing the adsorption sites for heavy metals and organic pollutants in water, resulting in poor adsorption performance; the dual-modified adsorbent of citric acid and titanium dioxide in Comparative Example 2 does not contain citric acid and nano-titanium dioxide, and cannot increase the adsorption sites and chemical stability of the microspheres through doping and acidification, reducing the adsorption capacity for heavy metal ions and organic pollutants and resulting in poor adsorption performance; the magnetic exfoliated bentonite-based aerogel material in Comparative Example 3 does not contain magnetic exfoliated bentonite and cannot form a magnetic three-dimensional network structure by cross-linking with a lamellar structure, reducing the adsorption capacity and adsorption efficiency for heavy metal ions and organic pollutants and resulting in poor adsorption performance.

[0111] Experimental Example 3

[0112] Cyclic stability experiment

[0113] Test samples: The titanium-loaded microbial solidified particulate water treatment agents prepared in Examples 1-4 and Comparative Examples 1-3.

[0114] Test method: Prepare a simulated polluted water with an antibiotic mass concentration of 100 mg / L and a heavy metal concentration of 100 mg / L, and the pH of the water body is 4.0 - 4.5. In this experiment, Pb 2+ heavy metal pollutant was used for the cyclic stability experiment. Weigh 1.0 g of the test sample and add it to 1000 mL of the simulated polluted water. Place it in a constant temperature oscillator (303 K, 120 rpm) and react for 24 h. Then filter it through a 0.45 μm organic filter membrane, take out the test sample, dry it in vacuum at 60 °C for 2 h, and put it into 1000 mL of the newly replaced simulated polluted water. After repeating the adsorption - taking out - drying experiment 20 times, the absorbance of Pb 2+ in the filtrate was measured at 520 nm using ultraviolet spectrophotometry. According to the formula in Experiment 2, the adsorption capacity Q 2+ of Pb (mg / g) was obtained, and then compared with the adsorption capacity Q 20 after one treatment in Experiment 2. The adsorption retention rate (%) was calculated according to the following formula: 1 The adsorption retention rate (%) = Q

[0115] / Q 20 × 100% 1

[0116] Figure 4 ​It is a graph showing the adsorption retention rate results of Examples 1-4 and Comparative Examples 1-3; as shown in the figure, the adsorption retention rates of Examples 1-4 are 88-93%, indicating better cycle stability; the adsorption retention rates of Comparative Examples 1-3 are 58-75%, indicating poor cycle stability; the dual-modified adsorbent of citric acid and titanium dioxide in Comparative Example 1 does not contain boehmite, and it is impossible to mechanically interlock the titanium microbial solidified particles with the magnetic exfoliated bentonite-based aerogel material in the shape of a sea urchin, reducing the structural stability and also being unfavorable for broadening the pH usage range of the aerogel material, resulting in poor cycle stability; the dual-modified adsorbent of citric acid and titanium dioxide in Comparative Example 2 does not contain citric acid and nano-titanium dioxide, and it is impossible to increase the chemical stability of the adsorbent by coating with citric acid and nano-titanium dioxide, and it is also unfavorable for enhancing the mechanical strength of the adsorbent, increasing the risk of collapse during multiple uses, resulting in poor cycle stability; the magnetic exfoliated bentonite-based aerogel material in Comparative Example 3 does not contain magnetic exfoliated bentonite, and it is impossible to be dispersed in the aerogel matrix in the form of single-layer or few-layer nanosheets through physical cross-linking or chemical bonding, which is unfavorable for enhancing the interfacial bonding and cannot effectively disperse stress, reducing the compressive strength, tensile strength and structural stability of the aerogel, resulting in poor cycle stability.

[0117] The above experimental results show that the bacterial activity, adsorption and cycle stability of Examples 1-4 of the present invention are significantly better than those of the samples of Comparative Examples 1-3. Among them, Example 1 using the drug-loaded nanoparticles with both magnetic and reactive oxygen dual-responsive properties and the modified carbon nanotube hydrogel carrier has stronger bacterial activity, better adsorption and better cycle stability. Loading the titanium-loaded microbial solidified particles on the magnetic exfoliated bentonite-based aerogel material can not only reduce the aggregation phenomenon of the titanium-loaded microbial solidified particles caused by the sea urchin shape, but also reduce the collapse risk of the aerogel, broaden the pH usage range of the aerogel material, further protect the activity of the microorganisms and the structural stability of the water treatment agent, which is beneficial for multiple cycle uses. At the same time, the dual-magnetic materials increase the adsorption performance for pollutants, and combined with the decomposition effect of the microorganisms, an efficient water purification effect is achieved.

[0118] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirits of the present invention.

[0119] The above describes the present invention and its embodiments, and this description is not restrictive. What is shown in the drawings is only one of the embodiments of the present invention, and the actual application is not limited thereto. Generally speaking, if those of ordinary skill in the art are inspired by it and design similar ways and embodiments without creative efforts without departing from the purpose of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A titanium-carrying microbial solidified granular water treatment agent, characterized in that: The titanium-loaded microbial solidified particle water treatment agent comprises the following components in parts by weight: 50-60 parts of a dual-modified adsorbent of citric acid and titanium dioxide, 20-30 parts of a magnetically exfoliated bentonite-based aerogel material, 1-2 parts of Bacillus subtilis, and 1-2 parts of Saccharomyces cerevisiae; the dual-modified adsorbent of citric acid and titanium dioxide comprises the following components in parts by weight: 30-40 parts of sea urchin-shaped magnetic composite nanoparticles, 10-20 parts of citric acid, and 6-10 parts of nano titanium dioxide; the magnetically exfoliated bentonite-based aerogel material comprises the following components in parts by weight: 5-8 parts of magnetically exfoliated bentonite, 8-10 parts of carboxylated cellulose nanofibers, and 1-3 parts of polyethyleneimine.

2. A method for preparing the titanium-carrying microbial solidified granular water treatment agent according to claim 1, characterized in that: The specific steps include: S1. Add 10.0 g of bentonite to a mixed solution of 500 mL of ultrapure water and anhydrous ethanol, wherein the volume ratio of ultrapure water to anhydrous ethanol is 1:2.5, and stir evenly. First, stir the mixed solution in a microwave at 600-800 W and 60 ° C for 1-2 h, and then perform ultrasonic dispersion treatment at 600-700 W for 1-2 h, and then vacuum dry at 60 ° C for 12 h to obtain a peeled bentonite sheet for standby use. Add 1.0-1.8 g of ferric chloride and 0.6 g of dichloromethane. Add ferric chloride to 100 mL of water, pre-react at 500-600 W and 60 ° C for 3-5 min, then add 10.5 mL of ammonia water, continue stirring at 500-600 W and 60 ° C for 0.5-1 h, then add the exfoliated bentonite flakes, fully stir for 1-2 h, cool to room temperature, collect the product by magnetic separation, wash with anhydrous ethanol and ultrapure water for several times until the pH reaches 7.0, finally vacuum dry and grind to obtain magnetic exfoliated bentonite; S2, adding 0.8-1.0g of carboxylated cellulose nanofibers into 100mL of ultrapure water, stirring with magnetic force to form a carboxylated cellulose nanofiber suspension, then adding a 50% by mass polyethyleneimine solution and the magnetic exfoliation bentonite described in step S1, stirring at 60-70°C for 3-4h, with a stirring speed of 200-300rpm, to obtain a magnetic exfoliation bentonite-based aerogel material; S3, 1.0-2.0g of Bacillus subtilis and 1.0-2.0g of Saccharomyces cerevisiae were inoculated into MSM basal salt medium, 1% glucose and 0.5% glycerol were added, and the pH was controlled to 6.5-7.

0. The viable bacteria concentration reached 10 at 28-30°C and 150-200rpm. 8 cfu / g, obtain bacterial liquid, centrifuge, discard the supernatant, collect active bacteria, then soak the citric acid and titanium dioxide double modified adsorbent in MSM basic salt medium for 6-8h, take it out and mix it with active bacteria, freeze-dry, and obtain titanium-loaded microbial solidified particles; S4. Add the titanium-loaded microbial solidified particles described in step S3 to the magnetically exfoliated bentonite-based aerogel material described in step S2, perform ultrasonic dispersion treatment for 0.5-1 h, and then freeze-dry to obtain a titanium-loaded microbial solidified particle water treatment agent.

3. The method for preparing the titanium-carrying microbial solidified granular water treatment agent according to claim 2, characterized in that: In step S2, the diameter of the carboxylated cellulose nanofibers is 4-10 nm and the length is 1-3 μm; the amount of polyethyleneimine solution added is 0.1-0.3 g.

4. The method for preparing the titanium-carrying microbial solidified granular water treatment agent according to claim 3, characterized in that: The preparation method of the dual-modified adsorbent of citric acid and titanium dioxide specifically comprises the following steps: (1) 3.5 g of ferric chloride hexahydrate was dissolved in 40 mL of ethylene glycol, 3.7 g of anhydrous sodium acetate was added at a stirring speed of 1000-2000 rpm until it was completely dissolved, and then transferred to a 50 mL polytetrafluoroethylene liner, sealed and placed in a reactor, and kept warm at 180-200°C for 10-12 h. The precipitate was collected by magnetic separation, washed with deionized water and anhydrous ethanol, and then vacuum dried at 60°C to obtain Fe3O4 microspheres; (2) dispersing the Fe3O4 microspheres described in step (1) in a mixed solution of 30 mL of anhydrous ethanol and 3 mL of water, ultrasonically treating for 3-5 min, then sequentially adding 1 mL of aqueous ammonia, 10 mL of anhydrous ethanol and 0.3-0.5 mL of tetraethyl orthosilicate, ultrasonically treating at 20-30° C. for 2-3 h, collecting the precipitate by magnetic separation, washing with deionized water and anhydrous ethanol, and then vacuum drying at 60° C. to obtain modified Fe3O4 microspheres; (3) adding sodium aluminate powder to 30 mL of water, stirring until dissolved, adding 0.3-0.5 g of urea, stirring for 0.5-1 h, then adding the modified Fe3O4 microspheres described in step (2), ultrasonically treating for 1-2 h, then transferring to a reactor, reacting at 160-180 ° C for 5-6 h, collecting the product by magnetic separation, washing with deionized water for 3-5 times, and then vacuum drying at 50 ° C to obtain sea urchin-shaped magnetic composite nanoparticles; (4) Dissolve 1.0-2.0 g of citric acid in 100 mL of water to form a citric acid solution for standby use. Disperse the sea urchin-shaped magnetic composite nanoparticles described in step (3) in 40 mL of dimethyl sulfoxide and stir at 100-200 rpm for 12 h. Then add 6 mL of ethyl orthosilicate and continue stirring for 3-5 h. Then add 0.6-1.0 g of nano-titanium dioxide and stir for 8-12 h. Centrifuge. Wash the precipitate twice with distilled water, vacuum dry it and immerse it in a citric acid solution. Stir it at 100-200 rpm for 24 h in a nitrogen atmosphere and then vacuum dry it to obtain a dual-modified adsorbent of citric acid and titanium dioxide.

5. The method for preparing the titanium-carrying microbial solidified granular water treatment agent according to claim 4, characterized in that: In step (3), the amount of sodium aluminate added is 0.1-0.2 g.

6. The method for preparing the titanium-carrying microbial solidified granular water treatment agent according to claim 5, characterized in that: In step (4), the nano titanium dioxide is of rutile type and has a particle size of 100-300 nm.

Images