Bacteriostatic bentonite cat litter and preparation method thereof

Abstract

The invention relates to bacteriostatic bentonite cat litter and a preparation method thereof, and belongs to the technical field of pet supplies. The bacteriostatic bentonite cat litter sequentially comprises a sodium bentonite matrix embedded with a bacteriostatic agent, a metal oxide layer and a biological membrane layer from inside to outside, the sodium bentonite matrix is obtained by mixing and aging bentonite and a sodium modifying agent in a solvent. When the biological membrane is in contact with excrement, the outer-layer biological membrane preferentially blocks liquid permeation, the middle-layer nano ZnO still generates active oxygen in a weak light environment, and the inner-layer Ag < + >-loaded zeolite slowly releases and inhibits bacteria, so that the antibacterial persistence can be improved. The bacteriostatic bentonite cat litter disclosed by the invention is remarkable in deodorization and antibacterial effects, does not stick to hands when being used, does not generate dust, and has relatively strong caking performance.

Description

Technical Field

[0001] This invention relates to the field of pet supplies technology, and in particular to an antibacterial bentonite cat litter and its preparation method. Background Technology

[0002] With improved economic conditions, pet ownership has become increasingly popular, especially cat ownership, which has seen significant growth in the past two years. China's pet cat population has jumped to second place globally. In urban households, cat litter has become a necessity for easy cleaning of cat waste. Its natural deodorizing and clumping properties, along with its relatively affordable price, have made it a popular choice for many pet owners, highlighting the huge consumer potential of the cat litter market. However, traditional cat litter products still have significant shortcomings: on the one hand, due to deficiencies in formula design and production processes, their deodorizing effect fails to meet the high standards required by modern households; on the other hand, dust problems are prominent. Traditional bentonite cat litter releases dust, which not only inconveniences the home environment but also easily damages the respiratory health of cats, inducing a series of related diseases. Therefore, dust control has become a core concern for cat owners. Furthermore, with the widespread adoption of smart litter boxes (automatic cleaning litter boxes), people tend to only clean the litter box when it's full, which inadvertently provides a breeding ground for bacteria for an extended period; when the survival rate of E. coli on the surface of the cat litter exceeds 50%, it threatens the health of pets.

[0003] Therefore, there is an urgent need to provide a bentonite cat litter with strong antibacterial properties and low dust content. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an antibacterial bentonite cat litter and its preparation method. The antibacterial bentonite cat litter of this invention exhibits significant deodorizing and antibacterial effects, is non-sticky during use, does not generate dust, and has strong clumping properties.

[0005] This invention is achieved through the following technical solution:

[0006] The first objective of this invention is to provide an antibacterial bentonite cat litter, wherein the structure of the antibacterial bentonite cat litter, from the inside out, consists of a sodium-modified bentonite matrix embedded with an antibacterial agent, a metal oxide layer, and a biofilm layer; the sodium-modified bentonite matrix is ​​obtained by mixing and aging bentonite with a sodium-modified agent in a solvent; the solvent is water.

[0007] In one embodiment of the present invention, the raw material components of the sodium bentonite matrix embedded with the antibacterial agent are, by weight: 76-82 parts bentonite, 3.1-3.5 parts sodium agent, 3-3.6 parts antibacterial agent, 1.5-2 parts deodorant, 4.5-6 parts calcium carbonate, and 1.2-1.5 parts liquid paraffin.

[0008] In one embodiment of the present invention, the antibacterial agent is Ag-loaded. +Zeolite; the Ag-loaded + The ammonia absorption value of zeolite is ≥90%;

[0009] And / or, the deodorizing agent is activated carbon.

[0010] In one embodiment of the present invention, the sodium bentonite matrix with embedded antibacterial agent is prepared by the following method:

[0011] The antibacterial agent, calcium carbonate, deodorant and liquid paraffin are mixed; the resulting mixed powder is then mixed with sodium bentonite matrix.

[0012] In one embodiment of the present invention, the interlayer spacing of the sodium bentonite matrix with embedded antibacterial agent is 1.45 nm to 1.55 nm.

[0013] In one embodiment of the present invention, the sodium-containing agent is food-grade sodium carbonate with a content of ≥99.8%;

[0014] And / or, the particle size of the sodium-modifying agent is 100-300 mesh;

[0015] And / or, the bentonite is calcium-based bentonite with a montmorillonite content of 75%;

[0016] And / or, the bentonite has a particle size of 100-300 mesh.

[0017] In one embodiment of the present invention, the aging conditions are: temperature of 25°C-35°C, relative humidity of 60%-70%, and time of 5-9 days.

[0018] In one embodiment of the present invention, the metal oxide in the metal oxide layer is nano zinc oxide;

[0019] And / or, the thickness of the metal oxide layer is 12μm-18μm.

[0020] In one embodiment of the present invention, the thickness of the biofilm layer is 18 μm-22 μm;

[0021] And / or, the biofilm layer is obtained by mixing chitosan and polyol in a weak acid solution and then spraying it onto the surface of a metal oxide layer.

[0022] In one embodiment of the present invention, the chitosan is chitosan with a degree of deacetylation ≥ 90%; the polyol is glycerol;

[0023] And / or, the mass ratio of chitosan to polyol is 0.46-0.58:1.

[0024] The second objective of this invention is to provide a preparation method for the aforementioned antibacterial bentonite cat litter, comprising the following steps:

[0025] S1. Mix bentonite with a sodium-modifying agent and age it to obtain a sodium-modified bentonite matrix;

[0026] S2. Mix the antibacterial agent, light calcium carbonate, deodorant and liquid paraffin to obtain a mixed powder; mix the obtained mixed powder with the sodium bentonite matrix obtained in step S1 and roll it to obtain a sodium bentonite matrix embedded with antibacterial agent.

[0027] S3. Spray a metal oxide suspension onto the surface of the sodium bentonite matrix with embedded antibacterial agent obtained in step S2 to obtain a metal oxide layer.

[0028] S4. The particles obtained in step S3 are coated with a biofilm solution and dried to obtain antibacterial bentonite cat litter.

[0029] In one embodiment of the present invention, the metal oxide suspension is obtained by sonicating the metal oxide and the dispersant in a solvent.

[0030] The technical solution of the present invention has the following advantages compared with the prior art:

[0031] (1) This invention provides an antibacterial bentonite cat litter and its preparation method. The antibacterial bentonite cat litter of this invention is constructed through a layered process, including a core antibacterial layer (loaded with Ag). + The structure comprises a gradient of zeolite, a photocatalytic layer (nano-ZnO), and a biofilm barrier layer (chitosan-glycerol). Upon contact with excrement, the outer biofilm preferentially blocks liquid permeation, the middle nano-ZnO layer still generates reactive oxygen species in low-light environments, and the inner Ag-loaded layer… + Zeolite slow-release antibacterial agents can enhance the duration of antibacterial activity.

[0032] (2) Under the aging conditions of this invention, sodium ion exchange promotes the expansion of the interlayer domain of bentonite, thereby increasing the Ag loading capacity. + Zeolite is embedded in the interlayer to form antibacterial microcapsules.

[0033] (3) This invention, through a unique "core-middle-outer layer" gradient structure design, enables the functional layers to be spatially ordered and temporally synergistic, jointly achieving a comprehensive effect of highly efficient antibacterial activity, deep deodorization, and low dust generation. (Contains Ag) + The zeolite's core antibacterial layer, serving as the core functional matrix, efficiently captures odor molecules such as ammonia and hydrogen sulfide in urine through physical adsorption. Simultaneously, Ag loaded with ion exchange... +Silver ions are continuously released, disrupting bacterial cell membranes and respiratory enzyme systems, inhibiting bacterial growth at its source, and effectively reducing odors caused by microbial metabolism. A photocatalytic layer (nano-ZnO) encapsulates the core, generating reactive oxygen species under visible or low-light conditions. These highly active substances further catalytically oxidize odor molecules (such as ammonia and organic amines) adsorbed by the core into harmless carbon dioxide and water, achieving deep decomposition of odors and avoiding the saturation and secondary release problems that may result from simple adsorption. A biofilm barrier layer (chitosan-glycerol): As the outermost protective membrane, this layer functions through the combined film-forming properties of chitosan and the moisturizing properties of glycerol. Chitosan, as a natural cationic polymer, has excellent antibacterial properties; in this structure, it forms a dense physical barrier that effectively encapsulates internal particles, reducing friction and damage during use. Glycerol molecules contain multiple hydrophilic hydroxyl groups, exhibiting strong moisturizing and lubricating effects. By maintaining a moderately moist state on the surface of the granules, it significantly reduces the dust generated by dry friction of cat litter granules. At the same time, its moisturizing properties help maintain the toughness of the chitosan membrane, making the barrier layer more durable and stable. Attached Figure Description

[0034] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0035] Figure 1 This is the XRD pattern of the sodium bentonite matrix with embedded antibacterial agent in Example 1 of the present invention;

[0036] Figure 2 This is the XRD pattern of the sodium bentonite matrix with embedded antibacterial agent in Comparative Example 3 of the present invention. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0038] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0039] Calcium-based bentonite with a montmorillonite content of 75% was purchased from Shuntian Mineral Products Processing Plant in Lingshou County;

[0040] Sodium carbonate was purchased from Gongyi Jiezhiyuan Water Treatment Materials Co., Ltd.

[0041] Ag + The zeolite was purchased from Xiamen Xindakang Inorganic Materials Co., Ltd.

[0042] Light calcium carbonate was purchased from Zhengzhou Renheng Chemical Products Co., Ltd.

[0043] Nano zinc oxide was purchased from Tuoyi New Materials (Guangzhou) Co., Ltd.

[0044] Sodium polyacrylate dispersant was purchased from Xi'an Tianmao Baoding Biotechnology Co., Ltd.

[0045] Chitosan was purchased from Shanghai Rantai Biotechnology Co., Ltd.

[0046] Glycerol was purchased from Shandong Shuntai New Materials Co., Ltd.

[0047] The activated carbon was purchased from Jiangxi Hongsen Activated Carbon Co., Ltd.

[0048] The liquid paraffin was purchased from Xinji Haorui Petrochemical Co., Ltd.

[0049] Example 1

[0050] This embodiment provides a method for preparing antibacterial bentonite cat litter, the specific steps of which are as follows:

[0051] Step 1: Preparation of sodium bentonite matrix

[0052] Take 80 parts by weight of calcium-based bentonite with a montmorillonite content of 75% (mass percentage), slowly add the calcium-based bentonite to 920 parts by weight of deionized water, and after uniform dispersion and stirring, prepare an 8% bentonite aqueous solution. While stirring the bentonite aqueous solution, slowly add 3.5 parts by weight of food-grade sodium carbonate (purity 99.8%) and mix well. Continue stirring for 1.5 hours. After uniform mixing, place the resulting slurry in a low-speed centrifuge (model TD5A, manufacturer: Changzhou Jintan Sanhe Instrument Co., Ltd.) for centrifugation. The speed is 3000 rpm and the centrifugation time is 10 minutes. The resulting slurry is aged at 30℃ and 65% RH for 7 days. After drying, the sodium-modified bentonite matrix is ​​obtained and pulverized to 200 mesh (D50 = 75 μm).

[0053] Step 2: Load Ag + Zeolite embedding

[0054] Three parts by weight were loaded with Ag + Zeolite (Ag) + The mass percentage of 0.8%, 200 mesh), 5 parts by weight of light calcium carbonate and 1.5 parts by weight of activated carbon were mixed and ball-milled for 30 min (200 rpm) to obtain composite powder (particle size D90 = 45 μm); the obtained composite powder was extruded and mixed evenly with 1.2 parts by weight of liquid paraffin; the resulting mixture and the sodium bentonite matrix obtained in step 1 were placed together in a drum and rolled at 50 rpm for 2 h. The zeolite was then embedded in the interlayer of the sodium bentonite matrix, and the interlayer spacing was measured to be 1.49 nm.

[0055] Step 3: Preparation of nano-ZnO suspension

[0056] Take 0.8 parts by weight of nano zinc oxide (particle size 30 nm) and disperse it in 5 parts by weight of deionized water. Add 0.1 parts by weight of sodium polyacrylate dispersant and sonicate (40 kHz, 30 min) to obtain ZnO suspension.

[0057] Step 4: Fluidized bed spraying

[0058] The material obtained in step 2 was placed in a fluidized bed with an inlet air temperature of 60℃ and a material temperature of 45℃. The ZnO suspension obtained in step 3 was sprayed at a rate of 12 mL / min, with the weight gain controlled at 3.2%, to form a uniform photocatalytic layer. Laser confocal microscopy showed that the thickness of the ZnO layer was 15 ± 3 μm.

[0059] Step 5: Preparation of chitosan-glycerol solution

[0060] Dissolve 1.5 parts by weight of chitosan (92% degree of deacetylation) in 60 parts by weight of 2.5 wt% acetic acid solution, add 0.7 parts by weight of glycerol, stir magnetically for 2 hours (40℃), and adjust the pH to 5.8 with citrate buffer to obtain chitosan-glycerol solution.

[0061] Step 6: Rotate the drum wrapper

[0062] The particles obtained in step 4 were placed in an inclined drum (35° inclination) and rotated at 30 rpm. Chitosan-glycerol solution was sprayed in (rate 10 mL / min). After coating, the particles were dried with hot air at 60°C to form a biofilm (thickness 20 ± 2 μm) to obtain antibacterial bentonite cat litter.

[0063] The contact angle of the biofilm, measured by the dynamic water droplet method (GB / T 30693), was 105±3°, indicating that the biofilm (chitosan-glycerol composite film) on the surface of the cat litter granules is hydrophobic, making it difficult for urine to spread on it. However, urine can be absorbed through the internal pores, reducing surface wetting of the granules and preventing cat hair from sticking together and dust from caking.

[0064] Comparative Example 1:

[0065] This comparative example provides a method for preparing cat litter, similar to Example 1, except that steps 3 and 4 (preparation and spraying of ZnO suspension) are omitted, and the ZnO layer is not coated; the remaining steps are consistent with Example 1.

[0066] Comparative Example 2:

[0067] This comparative example provides a method for preparing cat litter, similar to Example 1, except that:

[0068] Steps 5 and 6 (preparation of chitosan-glycerol solution and biofilm coating) are omitted, and the biofilm layer is not coated; the remaining steps are consistent with those in Example 1.

[0069] Comparative Example 3: Changes in Aging Conditions

[0070] This comparative example provides a method for preparing cat litter, which is similar to Example 1, except that in step 1, the aging temperature is 40°C, and the remaining steps are the same as in Example 1.

[0071] Comparative Example 4

[0072] This comparative example provides a common commercially available cat litter, purchased from the Nicole flagship store, which is sodium-based mineral cat litter.

[0073] Comparative Example 5

[0074] This comparative example provides a method for preparing cat litter, similar to Example 1, except that:

[0075] In steps 3 and 4, 0.8 parts by weight of nano-ZnO are directly dry-mixed with the raw materials in step 2. The remaining steps are consistent with those in Example 1.

[0076] Comparative Example 6

[0077] This comparative example provides a method for preparing cat litter, similar to Example 1, except that:

[0078] In step 2, 3 parts by weight of Ag are loaded. + Zeolite (Ag) + The mass percentage of the mixture is 0.8%, 200 mesh), 1.5 parts by weight of chitosan, 5 parts by weight of light calcium carbonate and 1.5 parts by weight of activated carbon. The mixture is ball-milled for 30 min (200 rpm) to obtain a composite powder (particle size D90 = 45 μm). The obtained composite powder is extruded and mixed evenly with 1.2 parts by weight of liquid paraffin. The resulting mixture and the sodium bentonite matrix obtained in step 1 are placed together in a drum and rolled at 50 rpm for 2 h. The zeolite is then embedded in the interlayer of the sodium bentonite matrix.

[0079] Steps 5 and 6 are replaced by: placing the particles obtained in step 4 into an inclined drum (tilt angle 35°), rotating it at a speed of 30 rpm, spraying in 0.7 parts by weight of glycerol (rate 10 mL / min), coating it, and then drying it with hot air at 60°C to form a biofilm (thickness 20±2 μm). The remaining steps are consistent with those in Example 1.

[0080] Test case

[0081] (1) Antibacterial performance test: The antibacterial performance (test method GB / T21510-2024) of the cat litter granules obtained in Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, and Comparative Example 6 was continuously compared. The results are shown in Table 1 below:

[0082] Table 1

[0083]

[0084] As can be seen from Table 1, the present invention can effectively inhibit Escherichia coli and Staphylococcus aureus, and the antibacterial effect is significantly better than that of the comparative example. This indicates that the nano ZnO layer and chitosan-glycerol biofilm in the present invention have significant antibacterial effects. The aging conditions in Example 1 improved the embedding rate of silver-loaded zeolite, and the antibacterial effect was higher than that of comparative example 3.

[0085] XRD analysis showed that the interlayer spacing of the zeolite embedded in the sodium bentonite matrix obtained in Example 1 was 1.49 nm. Figure 1 ), compared to control sample 3 ( Figure 2 The larger interlayer spacing (1.25 nm) (measured after step 2) indicates that Example 1 was able to embed more silver-loaded zeolite under different aging conditions. At a relatively mild temperature of 30°C, the water evaporation rate was moderate, allowing the system to maintain suitable humidity for a longer period. This facilitates the full, slow, and orderly entry of sodium ions into the bentonite interlayers, effectively replacing calcium ions, disrupting the interlayer charge balance, and making it easier for water molecules to enter. This results in a stable and sufficient expansion of the interlayer spacing, with a larger interlayer spacing facilitating subsequent embedding of Ag-loaded zeolite. + Zeolite composite powder provides superior physical space and embedding channels. During the drum rotation process, zeolite particles can more easily enter the interlayer, resulting in higher embedding volume and more uniform distribution.

[0086] (2) Dust rate

[0087] The cat litter granules obtained in Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, and Comparative Example 6 were subjected to dust rate testing. The specific experimental method was as follows: 1.25 kg of each of the seven test samples was taken and poured into the litter box at a speed of 100 g / s from a position 30 cm directly above the litter box (simulating the amount of litter added in a single-cat household and the height from which the litter was added). The concentration of inhalable particulate matter in the air at a distance of 30 cm directly above the litter box after the litter sample was poured was measured using a Yuante SKY8000 dust detector. Each sample was measured three times at the same pouring height, and the average value was taken. The results are shown in Table 2.

[0088] Table 2

[0089]

[0090] As shown in Table 2, the average PM2.5 value of Example 1, when poured from a height of 30 cm, was 26. Comparative Examples 1, 2, 3, 5, and 6 showed values ​​of 38.3, 42.3, 33, 35.3, and 36.3, respectively, while Comparative Example 4, made from commercially available cat litter, showed a value of 60.3. Compared to commercially available cat litter, the dust suppression effect of this invention is significant. The glycerol in this invention has moisturizing properties and acts as a wetting agent in the cat litter particles, thereby effectively reducing dust generation during use.

[0091] (3) Deodorization rate

[0092] The cat litter granules obtained in Examples 1, 1, 2, 3, 4, 5, and 6 were tested for deodorization rate. The specific experimental method was as follows: 100.00g of the cat litter sample was weighed and spread evenly in a clean petri dish. The petri dish was placed in the center of a sealed test chamber, and an appropriate amount of standard ammonia gas was injected into the chamber using a pipette. The air sampling pump was turned on to circulate the air in the sealed test chamber for 5 minutes to ensure uniform mixing of the ammonia gas. The initial ammonia concentration (C0) was measured and recorded using an ammonia gas detector, in ppm. This concentration should be controlled within the range of 10-20 ppm. The start time was recorded, allowing the cat litter sample to naturally adsorb ammonia gas in the test chamber. The ambient temperature and humidity were controlled within the specified range. 72 hours after the adsorption began, the ammonia concentration (C) in the test chamber was measured and recorded again using an ammonia gas detector. The results are shown in Table 3.

[0093] Table 3

[0094]

[0095] As shown in Table 3, the embodiment of the present invention achieved the highest deodorization rate of 98.02%. This effect stems from the synergistic system composed of activated carbon, nano-zinc oxide, and silver-loaded zeolite: the antibacterial core layer containing silver-loaded zeolite efficiently adsorbs and locks odor molecules through its porous structure, while simultaneously releasing Ag. + It inhibits bacterial growth, reducing odor generation at the source; the pollutants it accumulates provide a high-concentration reaction environment for the photocatalytic reaction of nano-zinc oxide, which effectively decomposes organic matter captured by the core, delays pore saturation, and generates active oxygen under photocatalysis, deeply degrading odor molecules; activated carbon not only directly adsorbs but also significantly increases the reaction interface as a carrier, improving overall efficiency. Through a cascade mechanism of "adsorption-enrichment-catalytic degradation-antibacterial," the three components achieve functional complementarity and multiplied efficiency, significantly improving deodorization efficiency and durability.

[0096] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A bacteriostatic bentonite cat litter, characterized by, The structure of the antibacterial bentonite cat litter, from the inside out, consists of a sodium-modified bentonite matrix embedded with an antibacterial agent, a metal oxide layer, and a biofilm layer; the sodium-modified bentonite matrix is ​​obtained by mixing and aging bentonite with a sodium-modifying agent in a solvent.

2. The bacteriostatic bentonite cat litter according to claim 1, characterized in that, By weight, the raw material components of the sodium bentonite matrix embedded with the antibacterial agent are: 76-82 parts bentonite, 3.1-3.5 parts sodium agent, 3-3.6 parts antibacterial agent, 1.5-2 parts deodorant, 4.5-6 parts calcium carbonate, and 1.2-1.5 parts liquid paraffin.

3. The bacteriostatic bentonite cat litter according to claim 2, characterized in that, The bacteriostatic agent is Ag+-loaded zeolite; the Ag + The ammonia absorption value of the zeolite is ≥ 90%.

4. The bacteriostatic bentonite cat litter of claim 1, wherein, The interlayer spacing of the sodium bentonite matrix with embedded antibacterial agent is 1.45nm-1.55nm.

5. The bacteriostatic bentonite cat litter according to claim 1, characterized in that, The sodium carbonate agent is food-grade sodium carbonate with a content of ≥99.8%; And / or, the particle size of the sodium-modifying agent is 100-300 mesh; And / or, the bentonite is calcium-based bentonite with a montmorillonite content of 75%; And / or, the bentonite has a particle size of 100-300 mesh.

6. The bacteriostatic bentonite cat litter according to claim 1, characterized in that, The aging conditions are: temperature of 25℃-35℃, relative humidity of 60%-70%, and time of 5-9 days.

7. The antibacterial bentonite cat litter according to claim 1, characterized in that, The metal oxide in the metal oxide layer is nano zinc oxide; And / or, the thickness of the metal oxide layer is 12μm-18μm.

8. The antibacterial bentonite cat litter according to claim 1, characterized in that, The thickness of the biofilm layer is 18μm-22μm; And / or, the biofilm layer is obtained by mixing chitosan and polyol in a weak acid solution and then spraying it onto the surface of a metal oxide layer.

9. The antibacterial bentonite cat litter according to claim 8, characterized in that, The chitosan is chitosan with a degree of deacetylation ≥ 90%; the polyol is glycerol; And / or, the mass ratio of chitosan to polyol is 0.46-0.58:

1.

10. The preparation method of the antibacterial bentonite cat litter according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Mix bentonite with a sodium-modifying agent and age it to obtain a sodium-modified bentonite matrix; S2. Mix the antibacterial agent, light calcium carbonate, deodorant and liquid paraffin to obtain a mixed powder; mix the obtained mixed powder with the sodium bentonite matrix obtained in step S1 and roll it to obtain a sodium bentonite matrix embedded with antibacterial agent. S3. Spray a metal oxide suspension onto the surface of the sodium bentonite matrix with embedded antibacterial agent obtained in step S2 to obtain a metal oxide layer. S4. The particles obtained in step S3 are coated with a biofilm solution and dried to obtain antibacterial bentonite cat litter.

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