Highly adsorptive modified bentonite cat litter and its preparation process

Abstract

The application belongs to the technical field of pet hygiene product materials, and particularly relates to a high-adsorption modified bentonite cat litter and a preparation process thereof. The cat litter is composed of sodium-based bentonite, hydroxyl aluminum tannin modified bentonite, cyclodextrin chitosan deodorization microspheres, pre-gelatinized starch and deionized water. The hydroxyl aluminum tannin modified bentonite is prepared by activating calcium-based bentonite with sodium carbonate, modifying the activated calcium-based bentonite with aluminum sulfate octadecahydrate and complexing the modified bentonite with tannic acid. The cyclodextrin chitosan deodorization microspheres are prepared by crosslinking chitosan, glacial acetic acid, cyclodextrin and sodium tripolyphosphate. The finished product is obtained by mixing, water spraying granulation, drying and screening, and has the characteristics of fast water absorption and clumping, good deodorization effect, low dust and high stability.

Description

Technical Field

[0001] This invention belongs to the field of pet hygiene product materials technology, specifically relating to a highly absorbent modified bentonite cat litter and its preparation process. Background Technology

[0002] As the pet ownership industry continues to expand, cat litter has gradually shifted from traditional filler materials to composite pet hygiene materials that combine multiple functions such as absorbency, clumping, odor control, low dust, and ease of cleaning. Bentonite, due to its layered aluminosilicate structure, water absorption and swelling capacity, and granulation properties, is widely used in clumping cat litter products. Existing bentonite cat litters typically use sodium-based bentonite as the main component, which rapidly expands and forms clumps after absorbing urine, thus achieving the function of cleaning and isolating contaminants. However, ordinary bentonite mainly relies on physical water absorption and mineral expansion to achieve clumping, and its ability to fix ammonium nitrogen, ammonia, and other volatile odor molecules in urine is limited. During use, problems such as rapid odor release, soft and wet clumping, bottom adhesion, and secondary dust generation can easily occur, affecting the user experience for both pets and owners.

[0003] To improve the deodorizing and adsorption properties of bentonite cat litter, existing technologies often involve directly mixing zeolite, activated carbon, diatomaceous earth, fragrances, antibacterial agents, or polymeric binders with bentonite. While these methods can temporarily improve adsorption or odor masking effects, most are simple physical blends lacking a stable bond between the functional components and the bentonite particles. This leads to delamination or detachment during transportation and use, resulting in significant fluctuations in product performance. Some products that mask odors with fragrances may also irritate pets' sense of smell and fail to fundamentally address the ammonia and sulfurous odors produced by urine decomposition. Products using a high proportion of organic binders or fine mineral powders, while improving wet clump strength, can cause uneven liquid absorption, surface gelation, increased dust, or higher costs, making it difficult to balance absorption speed, clump hardness, long-lasting deodorization, and industrial production costs.

[0004] Therefore, there is an urgent need to develop a modified bentonite cat litter with a simple structure, readily available raw materials, and a process suitable for large-scale production. This modified bentonite material should not only possess excellent water absorption and clumping properties but also enhance its ability to fix odor molecules through mineral surface modification and natural polymer cross-linking deodorizing structures. By introducing hydroxyaluminum tannin-modified bentonite into the cat litter system, the adsorption and fixation of ammonia and polar odor molecules can be achieved using metal hydroxyl sites, polyphenol complex structures, and the surface of bentonite sheets. Furthermore, the introduction of cyclodextrin-chitosan deodorizing microspheres can capture volatile odors using the inclusion effect of cyclodextrin and the cross-linking network of chitosan, while also helping to reduce dust dispersion. This composite modification approach facilitates a synergistic improvement in water absorption, clumping, deodorization, and low dust performance while reducing redundant mineral fillers and irritating masking components. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a highly absorbent modified bentonite cat litter and its preparation process.

[0006] In a first aspect, the present invention provides a highly absorbent modified bentonite cat litter comprising the following components in parts by weight: 78-90 parts of sodium-based bentonite, 4-8 parts of hydroxyaluminum tannin-modified bentonite, 1.5-4.0 parts of cyclodextrin-chitosan deodorizing microspheres, 1.5-4.0 parts of pregelatinized starch, and 10-18 parts of deionized water.

[0007] Preferably, the preparation method of the hydroxyaluminum tannin-modified bentonite includes: A1. By weight, add 100 parts of calcium-based bentonite to 300-500 parts of deionized water, stir and disperse, add 2.0-4.0 parts of sodium carbonate, and activate at 65-75℃ to obtain a bentonite dispersion; dissolve 6-12 parts of aluminum sulfate octahydrate in 80-120 parts of deionized water to obtain an aluminum salt solution; while stirring, add the aluminum salt solution dropwise to the bentonite dispersion, adjust the pH to 3.8-4.5, and continue stirring to obtain an aluminum-modified bentonite slurry; A2. Add 3-6 parts of tannic acid to the aluminum-modified bentonite slurry, stir and react at 45-55℃, let it stand for aging, filter, wash, dry, grind, and vibrate sieve.

[0008] In this invention, the formation process of hydroxyaluminum tannin-modified bentonite involves the sodium exchange of calcium-based bentonite, the adsorption exchange of hydroxyaluminum species, and the coordination complexation of tannic acid. After calcium-based bentonite is dispersed in deionized water, the interlamellar hydration is enhanced, and the montmorillonite lamellars gradually expand. Sodium carbonate dissolves, releasing sodium ions and carbonate ions. The sodium ions undergo cation exchange with the calcium ions originally present between the calcium-based bentonite lamellars, and the carbonate ions combine with the displaced calcium ions to form insoluble calcium carbonate precipitate, shifting the exchange reaction towards sodium exchange and resulting in a bentonite dispersion with increased sodium exchange. Aluminum sulfate octahydrate dissolves in deionized water to form an aluminum salt solution, and its hydrolysis products exist as positively charged hydroxyaluminum species under weakly acidic conditions. After adding aluminum salt solution dropwise to bentonite dispersion and adjusting the pH to a weakly acidic range, hydroxyl aluminum species enter the interlayer channels of bentonite sheets through cation exchange. They then adsorb and deposit at bond-breaking sites on the edges of the bentonite sheets and on the surface of silicon-oxygen tetrahedra, forming an aluminum-modified bentonite slurry with dispersed metal hydroxyl adsorption sites. Upon adding tannic acid, multiple phenolic hydroxyl groups in the tannic acid molecules undergo coordination complexation with the hydroxyl aluminum species to form aluminum-tannin polynuclear complexes. These complexes bind to the hydroxyl groups at the edges of the bentonite sheets through hydrogen bonding, constructing a complex structure layer on the sheet surface. After static aging to stabilize the deposition of the aluminum-tannin complex on the bentonite surface, the bentonite is then subjected to filtration, washing, drying, grinding, and vibrating sieving to finally obtain hydroxyl aluminum-tannin modified bentonite. The resulting modified bentonite retains the layered structure and water absorption and swelling properties of bentonite, while introducing a functional layer with dual active sites of phenolic and metal hydroxyl groups on its surface. This allows for the adsorption and fixation of alkaline odor molecules such as ammonia and other polar odor molecules.

[0009] Preferably, in step A1, the activation time at 65-75°C is 2-4 hours.

[0010] Preferably, in step A2, the stirring reaction time at 45-55°C is 2-3 hours.

[0011] Preferably, the preparation method of the cyclodextrin-chitosan deodorizing microspheres includes: B1. By weight, add 4-6 parts of glacial acetic acid to 250-400 parts of deionized water to obtain an acetic acid aqueous solution; add 15-25 parts of chitosan to the acetic acid aqueous solution, stir, add 10-20 parts of β-cyclodextrin, and continue stirring to obtain a chitosan-cyclodextrin composite solution; dissolve 3-5 parts of sodium tripolyphosphate in 200-300 parts of deionized water to obtain a sodium tripolyphosphate crosslinking solution; while stirring, add the sodium tripolyphosphate crosslinking solution to the chitosan-cyclodextrin composite solution, adjust the pH, and obtain a crosslinked microgel slurry. B2. The cross-linked microgel slurry is sheared and dispersed, allowed to stand for cross-linking, filtered, washed, dried, ground, and vibrated sieved.

[0012] In this invention, the formation process of cyclodextrin-chitosan deodorizing microspheres involves the acidification and proton dissolution of chitosan, the hydrogen bonding complexation of β-cyclodextrin, and the ionic crosslinking of chitosan by sodium tripolyphosphate. Glacial acetic acid is added to deionized water to form an aqueous acetic acid solution, providing a protonated environment for chitosan. After the chitosan is added to the aqueous acetic acid solution, the amino groups on the molecular chain combine with the protons released by acetic acid to form protonated amino groups. The original hydrogen bond network between the chitosan molecular chains is disrupted, and the molecular chains unfold and gradually dissolve in the solution, resulting in a homogeneous and transparent chitosan-acetic acid solution. After the addition of β-cyclodextrin, the hydroxyl groups on the outer surface of β-cyclodextrin form complexes with the hydroxyl and amino groups on the chitosan molecular chains through hydrogen bonding. The hydrophobic cavities inside the β-cyclodextrin molecules are retained in the solution, resulting in a chitosan-cyclodextrin composite solution. Sodium tripolyphosphate was dissolved in deionized water to obtain a sodium tripolyphosphate crosslinking solution, which was then added to a chitosan-cyclodextrin composite solution. Sodium tripolyphosphate ionized to generate tripolyphosphate ions with multiple negative charges, which underwent intermolecular and intramolecular electrostatic crosslinking reactions with the positively charged protonated amino groups on the chitosan molecular chains. This transformed the chitosan molecular chains from a dissolved state into a three-dimensional gel network, simultaneously encapsulating and fixing β-cyclodextrin molecules within the gel network, forming a crosslinked microgel slurry. Shear dispersion broke the crosslinked microgel slurry into micron-sized droplets. Static crosslinking allowed the ionic crosslinking reaction to proceed fully, further densifying the internal network of the microspheres. After filtration, washing, drying, grinding, and vibrating sieving, cyclodextrin-chitosan deodorizing microspheres were obtained. The resulting microspheres, with a chitosan-sodium tripolyphosphate ionic crosslinking network as the framework and β-cyclodextrin hydrophobic cavities uniformly distributed within the framework, possess an inclusion and trapping function for small-molecule volatile odor substances.

[0013] Preferably, in step B1, the pH is adjusted to 4.8-5.2.

[0014] Preferably, in step B2, the static crosslinking time is 2-4 hours.

[0015] A second aspect of the present invention provides a method for preparing the highly absorbent modified bentonite cat litter, comprising the following steps: S1. Under stirring, sodium-based bentonite, hydroxyaluminum tannin-modified bentonite, cyclodextrin chitosan deodorizing microspheres and pregelatinized starch are mixed to obtain a composite powder. S2. Spray deionized water into the composite powder, granulate to obtain wet cat litter granules; dry the wet cat litter granules and sieve them.

[0016] In this invention, the formation process of highly absorbent modified bentonite cat litter involves the physical compounding, granulation and bonding, and drying and shaping of various functional components. Sodium-based bentonite, hydroxyaluminum tannin-modified bentonite, cyclodextrin chitosan deodorizing microspheres, and pregelatinized starch are uniformly mixed under stirring. The powder particles are uniformly dispersed under mechanical shearing to obtain a composite powder. After deionized water is sprayed into the composite powder, the pregelatinized starch quickly absorbs water and swells to form a starch paste. The hydroxyl groups on the starch paste molecular chains bind to the surfaces of sodium-based bentonite, hydroxyaluminum tannin-modified bentonite, and cyclodextrin chitosan deodorizing microsphere particles through hydrogen bonding, building bonding bridges between particles. After the sodium-based bentonite particles absorb water, the montmorillonite flakes hydrate and swell, forming a hydrated colloidal layer on the particle surface, further enhancing the cohesion between particles. Under the rolling or squeezing action of the granulation equipment, the composite powder gradually agglomerates to form wet cat litter particles. Wet cat litter granules are dried at a set temperature, causing free water to evaporate and the pregelatinized starch paste to shrink and solidify. The sodium-based bentonite sheets retain structural water between their layers, forming dry granules with a certain strength. After sieving, highly absorbent modified bentonite cat litter with uniform particle size is obtained. The resulting cat litter granules form a composite structure with sodium-based bentonite as the main water-absorbing and swelling component, hydroxyaluminum tannin-modified bentonite as the ammonia odor adsorbing component, cyclodextrin-chitosan deodorizing microspheres as the volatile odor encapsulating component, and pregelatinized starch as the particle binding component. When encountering cat urine, the granules rapidly absorb water, swell, and agglomerate. During agglomeration, the hydration and expansion of sodium-based bentonite locks in liquid water, while the metal and phenolic hydroxyl sites on the surface of the hydroxyaluminum tannin-modified bentonite fix alkaline odor molecules such as ammonia. The hydrophobic cavities of the cyclodextrin-chitosan deodorizing microspheres trap volatile organic odor molecules, collectively exerting the functions of water absorption and agglomeration, ammonia fixation and deodorization, and dust suppression.

[0017] Preferably, in step S1, the mixing time is 15-25 minutes.

[0018] Preferably, in step S2, the drying temperature is 90-110°C.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention uses sodium-based bentonite as the main water-absorbing and clumping base, combined with hydroxyaluminum tannin-modified bentonite, cyclodextrin chitosan deodorizing microspheres, pregelatinized starch, and deionized water to produce granular cat litter. Sodium-based bentonite can quickly hydrate and swell upon contact with liquid, and pregelatinized starch forms a binding effect between particles, so that the wet cat litter particles have good particle integrity after drying. When in use, the cat litter can quickly form clumps after contact with urine, and the edges of the clumps are not easily loosened, making them less likely to break during cleaning, which can reduce the phenomenon of urine seeping into the bottom of the litter box and causing sticking.

[0020] (2) This invention uses hydroxyaluminum tannin-modified bentonite to improve the insufficient deodorizing ability of ordinary bentonite cat litter. The hydroxyaluminum tannin-modified bentonite is prepared from calcium-based bentonite, sodium carbonate, aluminum sulfate octadecyl hydrate, and tannic acid. It retains the water-absorbing and adsorbing properties of bentonite's lamellar structure while introducing a composite adsorption structure formed by hydroxyaluminum and tannic acid. This structure enhances the fixation of ammonia and polar odor molecules produced by urine decomposition, making it less prone to rapid odor dissipation and improving the odor control effect of the cat litter after absorbing liquid.

[0021] (3) This invention utilizes cyclodextrin-chitosan deodorizing microspheres to further enhance the capture capacity of volatile odors. The cyclodextrin-chitosan deodorizing microspheres are prepared from glacial acetic acid, deionized water, chitosan, β-cyclodextrin, and sodium tripolyphosphate. Chitosan helps to form a cross-linked microgel structure, while β-cyclodextrin helps to encapsulate small molecule odor substances. The cyclodextrin-chitosan deodorizing microspheres are distributed together with sodium bentonite, hydroxyaluminum tannin-modified bentonite, and pregelatinized starch in a composite powder. After granulation, drying, and sieving, the cat litter combines the effects of water absorption and clumping, clumping stability, odor suppression, and low dust. The formula is simplified, the raw materials are readily available, and it is suitable for large-scale production. Detailed Implementation

[0022] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0023] Example 1 This embodiment provides a preparation process for highly absorbent modified bentonite cat litter, the steps of which include: Step S1: Under stirring, add 84g of sodium-based bentonite, 6g of hydroxyaluminum tannin-modified bentonite, 2.75g of cyclodextrin chitosan deodorizing microspheres and 2.75g of pregelatinized starch into a mixing device, and mix at 80r / min for 20min to ensure uniform distribution of each component and obtain composite powder.

[0024] Step S2: Spray 14g of deionized water evenly into the composite powder within 10 minutes, stirring and mixing at 80r / min while spraying. After spraying, continue mixing for 10 minutes to form wet granules from the composite powder. Granulate the wet granules to control the particle size of the wet cat litter particles to 1.0-4.0mm. Dry the wet cat litter particles at 100℃ for 2 hours, and then sieve them using a 0.5mm sieve and a 4.0mm sieve to remove fine powder with a particle size less than 0.5mm and coarse particles with a particle size greater than 4.0mm, to obtain highly absorbent modified bentonite cat litter.

[0025] Preparation steps of hydroxyaluminum tannin modified bentonite: Step A1: Add 100g of calcium-based bentonite to 400g of deionized water and stir at 400r / min for 30min to disperse the calcium-based bentonite evenly without obvious agglomerates; add 3.0g of sodium carbonate and activate at 70℃ and 400r / min for 3h to obtain a bentonite dispersion; add 9g of aluminum sulfate octahydrate to 100g of deionized water and stir at 300r / min for 15min until completely dissolved to obtain an aluminum salt solution; while stirring at 400r / min, add the aluminum salt solution dropwise to the bentonite dispersion over 30min. After the addition is complete, adjust the pH to 4.15 with 1mol / L hydrochloric acid aqueous solution or 1mol / L sodium hydroxide aqueous solution, and continue stirring for 60min to obtain an aluminum-modified bentonite slurry.

[0026] Step A2: Add 4.5g of tannic acid to the aluminum-modified bentonite slurry, stir and react at 50℃ and 350r / min for 2.5h, then let it stand and age at 25℃ for 10h, filter, collect the filter cake, wash the filter cake three times with 200g of deionized water, dry at 80℃ for 12h, grind, and vibrate and sieve using a 75μm sieve to obtain hydroxyaluminum tannin-modified bentonite.

[0027] Preparation steps of cyclodextrin-chitosan deodorizing microspheres: Step B1: Add 5g of glacial acetic acid to 325g of deionized water and stir at 300r / min for 10min to obtain an acetic acid aqueous solution; add 20g of chitosan to the acetic acid aqueous solution and stir at 40℃ and 400r / min for 2h to fully disperse the chitosan and form a homogeneous system; add 15g of β-cyclodextrin and continue stirring at 40℃ and 400r / min for 1.5h to obtain a chitosan-cyclodextrin composite solution; dissolve 4g of sodium tripolyphosphate in 250g of deionized water and stir at 300r / min for 15min to obtain a sodium tripolyphosphate crosslinking solution; add the sodium tripolyphosphate crosslinking solution to the chitosan-cyclodextrin composite solution within 30min while stirring at 400r / min, adjust the pH to 5.0 with 1mol / L sodium hydroxide aqueous solution, and continue stirring for 30min to obtain a crosslinked microgel slurry.

[0028] Step B2: The cross-linked microgel slurry was sheared and dispersed at 6000 r / min for 5 min, then allowed to stand at 25℃ for 3 h for cross-linking, filtered, and the wet particles were collected. The particles were washed three times with 150 g of deionized water, dried at 60℃ for 10 h, ground, and sieved using a 150 μm sieve to obtain cyclodextrin chitosan deodorizing microspheres.

[0029] Example 2 This embodiment provides a preparation process for highly absorbent modified bentonite cat litter, the steps of which include: Step S1: Under stirring, add 78g of sodium-based bentonite, 4g of hydroxyaluminum tannin-modified bentonite, 1.5g of cyclodextrin chitosan deodorizing microspheres and 1.5g of pregelatinized starch into a mixing device, and mix at 80r / min for 15min to ensure uniform distribution of each component and obtain composite powder.

[0030] Step S2: Spray 10g of deionized water evenly into the composite powder within 10 minutes, stirring and mixing at 80r / min while spraying. After spraying, continue mixing for 10 minutes to form wet granules from the composite powder. Granulate the wet granules to control the particle size of the wet cat litter particles to 1.0-4.0mm. Dry the wet cat litter particles at 90℃ for 2 hours, and then sieve them using a 0.5mm sieve and a 4.0mm sieve to remove fine powder with a particle size less than 0.5mm and coarse particles with a particle size greater than 4.0mm, to obtain highly absorbent modified bentonite cat litter.

[0031] Preparation steps of hydroxyaluminum tannin modified bentonite: Step A1: Add 100g of calcium-based bentonite to 300g of deionized water and stir at 400r / min for 30min to disperse the calcium-based bentonite evenly without obvious agglomerates; add 2.0g of sodium carbonate and activate at 65℃ and 400r / min for 2h to obtain a bentonite dispersion; add 6g of aluminum sulfate octahydrate to 80g of deionized water and stir at 300r / min for 15min until completely dissolved to obtain an aluminum salt solution; while stirring at 400r / min, add the aluminum salt solution dropwise to the bentonite dispersion over 30min. After the addition is complete, adjust the pH to 3.8 with 1mol / L hydrochloric acid aqueous solution or 1mol / L sodium hydroxide aqueous solution, and continue stirring for 60min to obtain an aluminum-modified bentonite slurry.

[0032] Step A2: Add 3g of tannic acid to the aluminum-modified bentonite slurry, stir and react at 45℃ and 350r / min for 2h, then let it stand and age at 25℃ for 10h, filter, collect the filter cake, wash the filter cake three times with 200g of deionized water, dry at 80℃ for 12h, grind, and vibrate and sieve using a 75μm sieve to obtain hydroxyaluminum tannin-modified bentonite.

[0033] Preparation steps of cyclodextrin-chitosan deodorizing microspheres: Step B1: Add 4g of glacial acetic acid to 250g of deionized water and stir at 300r / min for 10min to obtain an acetic acid aqueous solution; add 15g of chitosan to the acetic acid aqueous solution and stir at 35℃ and 400r / min for 2h to fully disperse the chitosan and form a homogeneous system; add 10g of β-cyclodextrin and continue stirring at 35℃ and 400r / min for 1h to obtain a chitosan-cyclodextrin composite solution; dissolve 3g of sodium tripolyphosphate in 200g of deionized water and stir at 300r / min for 15min to obtain a sodium tripolyphosphate crosslinking solution; add the sodium tripolyphosphate crosslinking solution to the chitosan-cyclodextrin composite solution within 30min while stirring at 400r / min, adjust the pH to 4.8 with 1mol / L sodium hydroxide aqueous solution, and continue stirring for 30min to obtain a crosslinked microgel slurry.

[0034] Step B2: The cross-linked microgel slurry was sheared and dispersed at 6000 r / min for 5 min, then allowed to stand at 25℃ for 2 h for cross-linking, filtered, and the wet particles were collected. The particles were washed three times with 150 g of deionized water, dried at 60℃ for 10 h, ground, and sieved using a 150 μm sieve to obtain cyclodextrin chitosan deodorizing microspheres.

[0035] Example 3 This embodiment provides a preparation process for highly absorbent modified bentonite cat litter, the steps of which include: Step S1: Under stirring, add 90g of sodium-based bentonite, 8g of hydroxyaluminum tannin-modified bentonite, 4.0g of cyclodextrin chitosan deodorizing microspheres and 4.0g of pregelatinized starch into a mixing device, and mix at 80r / min for 25min to ensure uniform distribution of each component and obtain composite powder.

[0036] Step S2: Spray 18g of deionized water evenly into the composite powder within 10 minutes, stirring and mixing at 80r / min while spraying. After spraying, continue mixing for 10 minutes to form wet granules from the composite powder. Granulate the wet granules to control the particle size of the wet cat litter particles to 1.0-4.0mm. Dry the wet cat litter particles at 110℃ for 2 hours, and then sieve them using a 0.5mm sieve and a 4.0mm sieve to remove fine powder with a particle size less than 0.5mm and coarse particles with a particle size greater than 4.0mm, to obtain highly absorbent modified bentonite cat litter.

[0037] Preparation steps of hydroxyaluminum tannin modified bentonite: Step A1: Add 100g of calcium-based bentonite to 500g of deionized water and stir at 400r / min for 30min to disperse the calcium-based bentonite evenly without obvious agglomerates; add 4.0g of sodium carbonate and activate at 75℃ and 400r / min for 4h to obtain a bentonite dispersion; add 12g of aluminum sulfate octahydrate to 120g of deionized water and stir at 300r / min for 15min until completely dissolved to obtain an aluminum salt solution; while stirring at 400r / min, add the aluminum salt solution dropwise to the bentonite dispersion over 30min. After the addition is complete, adjust the pH to 4.5 with 1mol / L hydrochloric acid aqueous solution or 1mol / L sodium hydroxide aqueous solution, and continue stirring for 60min to obtain an aluminum-modified bentonite slurry.

[0038] Step A2: Add 6g of tannic acid to the aluminum-modified bentonite slurry, stir and react at 55℃ and 350r / min for 3h, then let it stand and age at 25℃ for 10h, filter, collect the filter cake, wash the filter cake three times with 200g of deionized water, dry at 80℃ for 12h, grind, and vibrate and sieve using a 75μm sieve to obtain hydroxyaluminum tannin-modified bentonite.

[0039] Preparation steps of cyclodextrin-chitosan deodorizing microspheres: Step B1: Add 6g of glacial acetic acid to 400g of deionized water and stir at 300r / min for 10min to obtain an acetic acid aqueous solution; add 25g of chitosan to the acetic acid aqueous solution and stir at 45℃ and 400r / min for 2h to fully disperse the chitosan and form a homogeneous system; add 20g of β-cyclodextrin and continue stirring at 45℃ and 400r / min for 2h to obtain a chitosan-cyclodextrin composite solution; dissolve 5g of sodium tripolyphosphate in 300g of deionized water and stir at 300r / min for 15min to obtain a sodium tripolyphosphate crosslinking solution; add the sodium tripolyphosphate crosslinking solution to the chitosan-cyclodextrin composite solution within 30min while stirring at 400r / min, adjust the pH to 5.2 with 1mol / L sodium hydroxide aqueous solution, and continue stirring for 30min to obtain a crosslinked microgel slurry.

[0040] Step B2: The cross-linked microgel slurry was sheared and dispersed at 6000 r / min for 5 min, then allowed to stand at 25℃ for 4 h for cross-linking, filtered, and the wet particles were collected. The particles were washed three times with 150 g of deionized water, dried at 60℃ for 10 h, ground, and sieved using a 150 μm sieve to obtain cyclodextrin chitosan deodorizing microspheres.

[0041] Comparative Example 1 The difference between this comparative example and Example 1 is that hydroxyaluminum tannin-modified bentonite is not added, and the amount of sodium-based bentonite is adjusted to 90g. The remaining steps are the same as in Example 1.

[0042] Comparative Example 2 The difference between this comparative example and Example 1 is that cyclodextrin-chitosan deodorizing microspheres are not added, and the amount of sodium bentonite is adjusted to 86.75g. The remaining steps are the same as in Example 1.

[0043] Comparative Example 3 The difference between this comparative example and Example 1 is that hydroxyaluminum tannin-modified bentonite and cyclodextrin-chitosan deodorizing microspheres are not added, and the amount of sodium-based bentonite is adjusted to 92.75g. The remaining steps are the same as in Example 1.

[0044] According to relevant national and industry standards, the performance of the highly absorbent modified bentonite cat litter provided in the above embodiments and comparative examples was tested. The test methods are as follows: The highly absorbent modified bentonite cat litter or comparative cat litter samples obtained in Examples 1-3 and Comparative Examples 1-3 were taken respectively and tested after equilibration for 24 hours in an environment with a temperature of 23°C and a relative humidity of 50%. Three parallel samples were set up for each test item and the average value was taken.

[0045] The water absorption rate test involves weighing 50.00g of sample and placing it in a 0.5mm mesh sieve container. Record the mass before water absorption. Immerse the sieve container vertically in 25℃ deionized water, ensuring the water level is 20mm above the sample surface. After soaking for 10 minutes, remove the sample and let it stand to drain for 5 minutes. Weigh the mass after water absorption. The water absorption rate is calculated as follows: water absorption rate = mass after water absorption minus mass before water absorption, divided by mass before water absorption, and multiplied by 100%.

[0046] The clumping time test was conducted by weighing 500.00g of sample and adding it to a circular container with an inner diameter of 200mm and a height of 80mm. The surface was leveled and the cat litter layer thickness was 50mm. 20mL of deionized water was added at a time from 50mm away from the sample surface using a pipette. Timing was started from the moment the deionized water touched the sample surface and stopped when there was no obvious free liquid on the wet clump surface and it could be lifted up as a whole with a flat spatula. The clumping time was recorded.

[0047] The agglomeration strength test was conducted by preparing a wet mass according to the agglomeration time test method. After the wet mass was formed, it was left to stand for 30 minutes in an environment with a temperature of 23℃ and a relative humidity of 50%. The mass was then completely removed with a flat spatula and placed in the center of the pressure testing instrument platform. A flat indenter was used to press down vertically at a speed of 10 mm / min. The maximum pressure when the mass broke was recorded as the agglomeration strength.

[0048] The dust rate test involves weighing 100.00g of sample and placing it in a standard sieve with a aperture of 0.075mm. The sample is then vibrated and sieved for 5 minutes on a vibrating sieve. The fine powder passing through the sieve is collected and weighed. The dust rate is calculated as the mass of the fine powder passing through the sieve divided by the mass of the sample before sieving and multiplied by 100%.

[0049] The pH test involves weighing 10.00g of sample and adding it to 100mL of deionized water. The mixture is stirred at 25℃ for 5 minutes, allowed to stand for 30 minutes, and then the supernatant is collected. The pH value is measured using a calibrated pH meter.

[0050] The ammonia removal rate test was conducted by weighing 5.00g of sample and spreading it evenly at the bottom of a 1L sealed glass container. An open dish containing 10mL of ammonia standard solution was placed inside the container and then immediately sealed. A blank container without sample was also prepared. After being placed at 25℃ for 2 hours, the ammonia concentration in the blank container and the sample container were measured using an ammonia detector. The ammonia removal rate was calculated as follows: ammonia removal rate = ammonia concentration in the blank container minus ammonia concentration in the sample container, divided by ammonia concentration in the blank container, and multiplied by 100%.

[0051] The performance test data above are shown in Table 1.

[0052] Table 1 Performance Test Results

[0053] As can be seen from the above, Examples 1-3 can effectively solve the problems of insufficient water absorption and clumping ability, low clumping strength, high dust rate, and unstable ammonia odor removal effect of ordinary bentonite cat litter compared to Comparative Examples 1-3.

[0054] The water absorption rates of Examples 1-3 were 310.6%, 299.8%, and 329.1%, respectively, all higher than the 270.5% of Comparative Example 3. This indicates that after adding hydroxyaluminum tannin-modified bentonite and cyclodextrin chitosan deodorizing microspheres to sodium-based bentonite, a composite structure that is more conducive to liquid absorption and retention is formed inside the cat litter particles.

[0055] The clumping times of Examples 1-3 were 35s, 37s, and 31s, respectively, which were significantly shorter than the 55s of Comparative Example 3. This indicates that the pregelatinized starch, hydroxyaluminum tannin-modified bentonite, and cyclodextrin-chitosan deodorizing microspheres together improved the rapid clumping ability of the particles after they came into contact with liquid, which could reduce the problem of urine sticking to the bottom caused by continued seepage.

[0056] The agglomeration strengths of Examples 1-3 were 28.4 N, 24 N, and 31.6 N, respectively, all higher than those of Comparative Example 1 (21.1 N), Comparative Example 2 (23.5 N), and Comparative Example 3 (17.8 N). This indicates that the hydroxyaluminum tannin-modified bentonite not only provides adsorption sites but also enhances the bonding stability between mineral particles within the wet agglomerate. The cyclodextrin-chitosan deodorizing microspheres also contribute to improving the agglomerate integrity.

[0057] The dust rates of Examples 1-3 were 0.72%, 0.95%, and 0.58%, respectively, which were lower than those of Comparative Example 1 (1.06%), Comparative Example 2 (1.28%), and Comparative Example 3 (1.85%). This indicates that the hydroxyl aluminum tannin-modified bentonite and cyclodextrin chitosan deodorizing microspheres, together with pregelatinized starch, reduced the tendency of fine powder to become free and particles to break.

[0058] The ammonia removal rates of Examples 1-3 were 94.6%, 90.8%, and 96.3%, respectively, which were significantly higher than those of Comparative Example 1 (74.9%), Comparative Example 2 (80.6%), and Comparative Example 3 (61.7%). Specifically, the ammonia removal rate of Comparative Example 1 decreased significantly due to the absence of hydroxyaluminum tannin-modified bentonite. The ammonia removal rate and dust rate of Comparative Example 2 both deteriorated due to the absence of cyclodextrin-chitosan deodorizing microspheres. Comparative Example 3 exhibited the weakest performance when both hydroxyaluminum tannin-modified bentonite and cyclodextrin-chitosan deodorizing microspheres were absent. This indicates that hydroxyaluminum tannin-modified bentonite primarily improves ammonia odor fixation, adsorption, and agglomeration strength, while cyclodextrin-chitosan deodorizing microspheres primarily improve volatile odor capture, particle coating, and low dust performance. The synergistic effect of these two components allows the cat litter to simultaneously possess high water absorption, short agglomeration time, high agglomeration strength, low dust rate, and high ammonia removal rate.

[0059] The pH values ​​of Examples 1-3 were 8.0-8.4, which are close to those of Comparative Examples 1-3 (8.1-8.3). This indicates that the performance improvement does not depend on the adjustment of strong acids or bases, but rather on the structural effect of the hydroxyaluminum tannin-modified bentonite and cyclodextrin-chitosan deodorizing microspheres, thereby achieving a comprehensive improvement in high adsorption, rapid agglomeration, strong deodorization, and low dust.

Claims

1. A highly absorbent modified bentonite cat litter, characterized in that, It includes the following components in parts by weight: 78-90 parts sodium bentonite, 4-8 parts hydroxyaluminum tannin modified bentonite, 1.5-4.0 parts cyclodextrin chitosan deodorizing microspheres, 1.5-4.0 parts pregelatinized starch, and 10-18 parts deionized water.

2. The highly absorbent modified bentonite cat litter according to claim 1, characterized in that, The preparation method of the hydroxyaluminum tannin modified bentonite includes: A1. By weight, add 100 parts of calcium-based bentonite to 300-500 parts of deionized water, stir and disperse, add 2.0-4.0 parts of sodium carbonate, and activate at 65-75℃ to obtain a bentonite dispersion; dissolve 6-12 parts of aluminum sulfate octahydrate in 80-120 parts of deionized water to obtain an aluminum salt solution; while stirring, add the aluminum salt solution dropwise to the bentonite dispersion, adjust the pH to 3.8-4.5, and continue stirring to obtain an aluminum-modified bentonite slurry; A2. Add 3-6 parts of tannic acid to the aluminum-modified bentonite slurry, stir and react at 45-55℃, let it stand for aging, filter, wash, dry, grind, and vibrate sieve.

3. The highly absorbent modified bentonite cat litter according to claim 2, characterized in that, In step A1, the activation time at 65-75℃ is 2-4 hours.

4. The highly absorbent modified bentonite cat litter according to claim 2, characterized in that, In step A2, the reaction is stirred at 45-55℃ for 2-3 hours.

5. The highly absorbent modified bentonite cat litter according to claim 1, characterized in that, The preparation method of the cyclodextrin-chitosan deodorizing microspheres includes: B1. By weight, add 4-6 parts of glacial acetic acid to 250-400 parts of deionized water to obtain an acetic acid aqueous solution; add 15-25 parts of chitosan to the acetic acid aqueous solution, stir, add 10-20 parts of β-cyclodextrin, and continue stirring to obtain a chitosan-cyclodextrin composite solution; dissolve 3-5 parts of sodium tripolyphosphate in 200-300 parts of deionized water to obtain a sodium tripolyphosphate crosslinking solution; while stirring, add the sodium tripolyphosphate crosslinking solution to the chitosan-cyclodextrin composite solution, adjust the pH, and obtain a crosslinked microgel slurry. B2. The cross-linked microgel slurry is sheared and dispersed, allowed to stand for cross-linking, filtered, washed, dried, ground, and vibrated sieved.

6. The highly absorbent modified bentonite cat litter according to claim 5, characterized in that, In step B1, adjust the pH to 4.8-5.

2.

7. The highly absorbent modified bentonite cat litter according to claim 5, characterized in that, In step B2, the static crosslinking time is 2-4 hours.

8. A method for preparing highly adsorbent modified bentonite cat litter according to any one of claims 1-7, characterized in that, step include: S1. Under stirring, sodium-based bentonite, hydroxyaluminum tannin-modified bentonite, cyclodextrin chitosan deodorizing microspheres and pregelatinized starch are mixed to obtain a composite powder. S2. Spray deionized water into the composite powder, granulate to obtain wet cat litter granules; dry the wet cat litter granules and sieve them.

9. The method for preparing highly adsorbent modified bentonite cat litter according to claim 8, characterized in that, In step S1, the mixing time is 15-25 minutes.

10. The method for preparing highly adsorbent modified bentonite cat litter according to claim 8, characterized in that, In step S2, the drying temperature is 90-110℃.

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