A multi-layer coated structure olive kernel cat litter particle

Abstract

This invention relates to the field of pet material technology, and more particularly to a multi-layered coated olive pit cat litter granule, comprising a core layer, a middle layer, and an outer layer. The core layer contains olive pit particles with a particle size of 1.5–3.0 mm. The middle layer coats the outer surface of the core layer and contains guar gum, sodium carboxymethyl cellulose, and zeolite powder. The outer layer coats the outer surface of the middle layer and contains ZAG complex, sodium bicarbonate, vegetable oil, and surfactant. The multi-layered coated olive pit cat litter granule provided by this invention achieves significant improvements in comprehensive performance across multiple dimensions, including water absorption, breakage resistance, deodorization, and antibacterial properties.

Description

Technical Field

[0001] This invention relates to the field of pet materials technology, and in particular to a multi-layered coated olive pit cat litter granule. Background Technology

[0002] Olive pits, a major byproduct of the olive oil processing industry, are a widely available and cost-effective biomass material. In the ongoing development of the global olive oil industry, approximately 0.3-0.5 tons of olive pits are generated for every ton of olive oil produced. If these byproducts are not properly utilized, most are incinerated or landfilled, resulting in a serious waste of biomass resources and environmental pollution. From a material perspective, olive pits are hard, have high mechanical strength, are not easily broken or pulverized, and possess a well-developed internal porous structure with excellent adsorption properties. Furthermore, they are rich in lignocellulose and polyphenols, among which polyphenols are natural antibacterial agents that effectively inhibit the growth of common harmful microorganisms such as Escherichia coli and Staphylococcus aureus.

[0003] As an essential product for cat owners, cat litter is experiencing a continuous increase in market demand. Meanwhile, users' functional requirements for cat litter have expanded from the initial core functions of absorbency and clumping to include low dust, strong odor control, biodegradability, antibacterial properties, and user comfort. Traditional cat litter products (such as bentonite cat litter) have good clumping properties, but they suffer from drawbacks such as high dust levels, potential respiratory discomfort in cats, non-biodegradability, and environmental pollution. Existing biodegradable cat litters (such as corn litter and tofu litter) generally have weak adsorption capacity, poor odor control, and are prone to bacterial growth, failing to meet pet owners' demands for high-quality cat litter. Based on the abundant resources and excellent natural properties of olive pits, as well as the urgent demand in the cat litter market for multifunctional and environmentally friendly products, using olive pits as the core raw material in cat litter production can not only realize the resource utilization of olive pit by-products and reduce the environmental burden, but also rely on its own porous structure and natural antibacterial components to produce a new type of cat litter with comprehensive properties such as low dust, strong adsorption, excellent deodorization, biodegradability, and antibacterial properties. This makes up for the performance shortcomings of traditional cat litter, fits the green and healthy development trend of the pet industry, and has important economic value and environmental significance.

[0004] In existing technologies, olive pits are inherently hard, and although their porous structure is well-developed, it is mostly closed or semi-closed. Without special modification, water penetration is slow, and once saturated with water, they are difficult to form tight clumps quickly, easily resulting in clumping and sticking to the bottom, increasing cleaning difficulty. Secondly, dust control is difficult. During the crushing and grinding process, olive pits easily generate fine wood dust. Even after screening, dust may still fly during use, which may irritate the cat's respiratory tract with long-term use and pollute the living environment. Thirdly, the deodorizing effect is not long-lasting. The natural deodorizing ability of olive pits mainly relies on their own pores for adsorption, but their adsorption capacity is limited. After absorbing cat excrement, odors are easily released from the pores, especially in high temperature and humid environments, where the deodorizing effect decays quickly, making it difficult to maintain a fresh environment for a long time. Fourthly, the mechanical strength is uneven. Under some processing techniques, olive pit particles are prone to brittleness. They are easily broken and pulverized after being stepped on or scratched by cats, which not only reduces the lifespan of the cat litter but also further increases the amount of dust. Summary of the Invention

[0005] To address the problems mentioned in the background section, this invention provides a multi-layered coated olive pit cat litter granule.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention discloses a multi-layered coated olive pit cat litter granule. The cat litter granule adopts a multi-layered coated structure design, and the components and parameters of each layer are as follows: The multi-layered olive pit cat litter granules consist of a core layer, a middle layer, and an outer layer, with the three layers sequentially covering each other to form a complete cat litter granule.

[0007] The core layer contains olive pit particles with a particle size of 1.5–3.0 mm. The olive pit particles are uniformly spherical or near-spherical with a particle size deviation of no more than ±0.2 mm. The olive pit particles in the core layer are obtained by crushing and screening olive pit residue. The crushing is carried out using a universal crusher with a crushing speed of 2000–3000 r / min. The screening is carried out using a standard inspection sieve with screen apertures of 3.0 mm and 1.5 mm, and the screening time is 10–15 min. The olive pit particles have a moisture content of 8–10%, preferably 8.5–9.5%; a total lignin and cellulose content of 30–40%, of which the lignin content is 12–18% and the cellulose content is 18–22%; a porosity of 45–55%, preferably 48–52%; a water absorption rate of not less than 120% of its own weight, preferably 125–150%; and a breakage rate of not more than 5%, preferably 2–4%. The breakage rate test conditions are as follows: 100g of sample is placed in a 250mL beaker, 100mL of deionized water is added, and after standing for 24h, it is passed through a 1.0mm sieve, and the mass of the remaining sample on the sieve is weighed to calculate the breakage rate.

[0008] An intermediate layer coats the outer surface of the core layer, with a coverage rate of not less than 98%. The intermediate layer comprises guar gum, sodium carboxymethyl cellulose, and zeolite powder, wherein the zeolite powder has a particle size of 100–200 mesh, the guar gum viscosity is 5000–8000 mPa·s (25°C, 2% aqueous solution), and the sodium carboxymethyl cellulose has a degree of substitution of 0.6–0.8. In the intermediate layer, the mass ratio of guar gum, sodium carboxymethyl cellulose, and zeolite powder is (3–4):(2–3):(1–2), preferably 3.5:(2.2–2.8):(1.2–1.8). The thickness of the intermediate layer is 0.15–0.30 mm, preferably 0.18–0.28 mm.

[0009] An outer layer coats the outer surface of the intermediate layer, with a coverage rate of not less than 95%. The outer layer comprises a ZAG complex, sodium bicarbonate, vegetable oil, and a surfactant, wherein the sodium bicarbonate has a particle size of 80–120 mesh, and the surfactant has an HLB value of 10–12. In the outer layer, the mass ratio of the ZAG complex, sodium bicarbonate, vegetable oil, and surfactant is (0.8–1.2):(0.5–1.0):(0.3–0.8):(0.1–0.3), preferably (0.9–1.1):(0.6–0.9):(0.4–0.7):(0.15–0.25). The thickness of the outer layer is 0.05–0.12 mm, preferably 0.06–0.10 mm.

[0010] The vegetable oil is coconut oil, which is food-grade refined coconut oil with an acid value ≤0.1 mg KOH / g and an iodine value of 7–11 g I2 / 100g; the surfactant is an alkyl glycoside with an alkyl carbon chain length of C12–C14 and a purity ≥98%.

[0011] The ZAG complex is a composite formed by oxidative grafting of ε-polylysine onto sodium alginate, followed by coordination crosslinking with zirconium ions. The ZAG complex has a particle size of 50–100 nm and a crosslinking degree of 30–40%. The ZAG complex is prepared by the following method: sodium alginate is oxidized with sodium periodate at a molar ratio of 0.1–0.15:1, at an oxidation temperature of 25–30°C, and for 1–2 h, resulting in an aldehyde degree of 5–8%, preferably 6–7%, to obtain oxidized sodium alginate; the oxidized sodium alginate is then reacted with ε-polylysine using a Schiff base reaction to obtain a graft copolymer; the graft copolymer is then crosslinked with zirconium oxychloride at pH 4.5–5.0, with pH adjusted using a 0.1 mol / L hydrochloric acid or sodium hydroxide solution.

[0012] The Schiff base reaction conditions are as follows: the mass ratio of sodium alginate oxide to ε-polylysine is (4–6):1, preferably (4.5–5.5):1; the reaction temperature is 35–45℃, preferably 38–42℃; the reaction time is 2–3h, preferably 2.2–2.8h; the pH of the reaction system is 7.0–7.5, and the pH is adjusted using a 0.1mol / L sodium carbonate solution; in the coordination crosslinking reaction, the mass ratio of the graft copolymer to zirconium oxychloride is (8–10):1, preferably (8.5–9.5):1; the reaction time is 1–1.5h, preferably 1.2–1.4h; and the reaction temperature is 25–30℃, preferably 26–28℃.

[0013] The total particle size of the multi-layered coated olive pit cat litter granules is 1.8–3.5 mm, with a uniform particle size distribution and a D50 of 2.2–2.8 mm. Based on the total mass of the cat litter granules, the core layer has a mass fraction of 85–90%, preferably 86–89%, the middle layer has a mass fraction of 6–9%, preferably 7–8%, and the outer layer has a mass fraction of 1.7–3.3%, preferably 2.0–3.0%.

[0014] The beneficial effects of this invention are: 1. The core layer uses olive pit particles with a particle size of 1.5–3.0 mm, a porosity of 45–55%, and a total lignocellulose content of 30–40%. Its abundant natural pores and capillary structure form the first physical adsorption barrier, enabling rapid absorption of liquids and initial fixation of odor molecules. In the middle layer, guar gum and sodium carboxymethyl cellulose are both hydrophilic polymers. They form a dense hydrogel network on the surface of the core layer, rapidly swelling upon contact with water to lock in moisture and form a film. Simultaneously, the microporous structure and cation exchange properties of zeolite powder effectively adsorb polar odor molecules such as ammonia. The ZAG complex in the outer layer is a three-dimensional network structure formed by oxidative grafting of sodium alginate with ε-polylysine and then coordinating and crosslinking with zirconium ions. Its chain segments are rich in carboxyl groups, aldehyde groups and zirconium coordination centers. It can achieve deep deodorization by binding with metal ions or polar molecules through coordination, and can also form interlayer interlocking with sodium carboxymethyl cellulose and guar gum in the middle layer through hydrogen bonding or electrostatic interaction, ensuring the overall stability of the multilayer structure.

[0015] 2. The ε-polylysine in the outer ZAG complex is a broad-spectrum antimicrobial peptide. It is grafted onto the sodium alginate molecular chain via a Schiff base reaction, and then cross-linked by zirconium ions to form a stable cross-linked network. This network effectively encapsulates and slowly releases ε-polylysine, allowing it to be continuously released during cat litter use, thus effectively inhibiting bacterial growth and reducing odor sources. Simultaneously, the sodium bicarbonate added to the outer layer slowly releases carbon dioxide upon contact with water or in humid environments, creating a slightly alkaline environment that synergistically enhances the antibacterial effect with ε-polylysine and neutralizes acidic components in urine, further reducing odor.

[0016] 3. The core layer of olive pit granules, after being crushed and sieved, has a moisture content controlled at 8-10% and a breakage rate not exceeding 5%, ensuring the mechanical strength and wear resistance of the granules and preventing excessive dust generation during use. The continuous coating of the middle and outer layers forms a smooth and dense surface, reducing the risk of dust generation due to friction between granules. The added vegetable oil and surfactants in the outer layer form a skin-friendly film on the granule surface, giving the cat litter good wettability and uniform clumping, while also reducing urine residue and sticking. The surfactant is an alkyl glycoside derived from renewable plant resources, possessing both biodegradability and low irritation. Together with natural or bio-based components such as olive pits, sodium alginate, and ε-polylysine, it ensures the overall biodegradability of the product, aligning with green environmental protection principles. Detailed Implementation

[0017] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1 This embodiment provides a multi-layered coated olive pit cat litter granule, with the components and parameters of each layer as follows: Core layer: Olive pit residue is obtained by crushing it in a universal pulverizer (2000 r / min) and sieving it in a standard test sieve (3.0 mm and 1.5 mm mesh size) for 10 min. The olive pit particles have a particle size of 1.5 mm, are nearly spherical, and have a particle size deviation of ±0.15 mm. 900 g of these olive pit particles are taken as the core layer. The core layer has a moisture content of 8%, a lignin content of 12%, a cellulose content of 18%, a porosity of 45%, a water absorption rate of 120%, and a breakage rate of 5%.

[0019] Intermediate layer: Coated on the outer surface of the core layer, with a coverage rate of 98% and a thickness of 0.15 mm; Take 70 g of intermediate layer raw materials, including 30 g of guar gum, 20 g of sodium carboxymethyl cellulose, and 20 g of zeolite powder. The particle size of the zeolite powder is 100 mesh, the viscosity of the guar gum is 5000 mPa·s (25℃, 2% aqueous solution), and the degree of substitution of sodium carboxymethyl cellulose is 0.6.

[0020] Outer layer: Coated on the outer surface of the middle layer, with a coverage rate of 95% and a thickness of 0.05 mm; Take 30 g of outer layer raw materials, including 8 g of ZAG complex, 5 g of sodium bicarbonate, 3 g of coconut oil, and 1 g of alkyl glycoside. The sodium bicarbonate has a particle size of 80 mesh, the alkyl glycoside has an alkyl carbon chain length of C12, a purity of 98%, and an HLB value of 10; the coconut oil has an acid value of 0.08 mg KOH / g and an iodine value of 7 g I2 / 100 g.

[0021] Preparation of ZAG complex: Take 100g sodium alginate, add 12.4g sodium periodate (sodium periodate to sodium alginate molar ratio 0.1:1), oxidize at 25℃ for 1h, and obtain oxidized sodium alginate with 5% aldehyde degree; take 40g oxidized sodium alginate and 10g ε-polylysine (mass ratio 4:1), react at 35℃ and pH 7.0 (adjusted with 0.1mol / L sodium carbonate solution) for 2h to complete the Schiff base reaction, and obtain the graft copolymer; take 80g graft copolymer and 10g zirconium oxychloride (mass ratio 8:1), react at 25℃ and pH 4.5 (adjusted with 0.1mol / L hydrochloric acid) for 1h to complete the coordination crosslinking, and obtain ZAG complex (particle size 50nm, crosslinking degree 30%).

[0022] The total mass of the cat litter granules is 1000g (900g core layer + 70g middle layer + 30g outer layer), with a total particle size of 1.8mm and a D50 of 2.2mm. By total mass, the core layer accounts for 90% of the mass, the middle layer accounts for 7% of the mass, and the outer layer accounts for 3% of the mass.

[0023] Example 2 This embodiment provides a multi-layered coated olive pit cat litter granule, with the components and parameters of each layer as follows: Core layer: Olive pit residue is obtained by crushing it in a universal pulverizer (2500 r / min) and sieving it in a standard test sieve (3.0 mm and 1.5 mm mesh size) for 12 min. The olive pit particles have a particle size of 2.2 mm, are spherical, and have a particle size deviation of ±0.2 mm. 900 g of these olive pit particles are taken as the core layer. The core layer has a moisture content of 9%, a lignin content of 15%, a cellulose content of 20%, a porosity of 50%, a water absorption rate of 135%, and a breakage rate of 3%.

[0024] Intermediate layer: Coated on the outer surface of the core layer, with a coverage rate of 99% and a thickness of 0.22 mm; Take 75 g of intermediate layer raw materials, including 35 g of guar gum, 25 g of sodium carboxymethyl cellulose, and 15 g of zeolite powder. The particle size of the zeolite powder is 150 mesh, the viscosity of the guar gum is 6500 mPa·s (25℃, 2% aqueous solution), and the degree of substitution of sodium carboxymethyl cellulose is 0.7.

[0025] Outer layer: Coated on the outer surface of the middle layer, with a coverage rate of 97% and a thickness of 0.08 mm; Take 25 g of outer layer raw materials, including 10 g of ZAG complex, 7 g of sodium bicarbonate, 5 g of coconut oil, and 2 g of alkyl glycoside. The sodium bicarbonate has a particle size of 100 mesh, the alkyl glycoside has an alkyl carbon chain length of C13, a purity of 99%, and an HLB value of 11; the coconut oil has an acid value of 0.05 mg KOH / g and an iodine value of 9 g I2 / 100 g.

[0026] Preparation of ZAG complex: 100g sodium alginate was added to 14.9g sodium periodate (molar ratio of sodium periodate to sodium alginate 0.12:1), and oxidized at 28℃ for 1.5h to obtain oxidized sodium alginate with a degree of aldehyde of 6.5%; 50g oxidized sodium alginate was reacted with 10g ε-polylysine (mass ratio 5:1) at 40℃ and pH 7.2 (adjusted with 0.1mol / L sodium carbonate solution) for 2.5h to complete the Schiff base reaction and obtain the graft copolymer; 90g graft copolymer was reacted with 10g zirconium oxychloride (mass ratio 9:1) at 28℃ and pH 4.8 (adjusted with 0.1mol / L hydrochloric acid) for 1.2h to complete the coordination crosslinking and obtain the ZAG complex (particle size 75nm, degree of crosslinking 35%).

[0027] The total mass of the cat litter granules is 1000g (900g core layer + 75g middle layer + 25g outer layer), with a total particle size of 2.6mm and a D50 of 2.5mm. By total mass, the core layer accounts for 90% of the mass, the middle layer accounts for 7.5% of the mass, and the outer layer accounts for 2.5% of the mass.

[0028] Example 3 This embodiment provides a multi-layered coated olive pit cat litter granule, with the components and parameters of each layer as follows: Core layer: Olive pit residue is obtained by crushing it in a universal pulverizer (3000 r / min) and sieving it in a standard test sieve (3.0 mm and 1.5 mm mesh size) for 15 min. The olive pit particles have a particle size of 3.0 mm, are nearly spherical, and have a particle size deviation of ±0.18 mm. 890 g of these olive pit particles are taken as the core layer. The moisture content is 10%, the lignin content is 18%, the cellulose content is 22%, the porosity is 55%, the water absorption rate is 150%, and the breakage rate is 2%.

[0029] Intermediate layer: Coated on the outer surface of the core layer, with a coverage rate of 100% and a thickness of 0.30 mm; 77 g of intermediate layer raw materials are taken, including 40 g of guar gum, 30 g of sodium carboxymethyl cellulose, and 7 g of zeolite powder. The particle size of the zeolite powder is 200 mesh, the viscosity of the guar gum is 8000 mPa·s (25℃, 2% aqueous solution), and the degree of substitution of sodium carboxymethyl cellulose is 0.8.

[0030] Outer layer: Coated on the outer surface of the middle layer, with a coverage rate of 98% and a thickness of 0.12 mm; 33 g of outer layer raw materials were taken, including 12 g of ZAG complex, 10 g of sodium bicarbonate, 8 g of coconut oil, and 3 g of alkyl glycoside. The sodium bicarbonate had a particle size of 120 mesh, the alkyl glycoside had an alkyl carbon chain length of C14, a purity of 99.5%, and an HLB value of 12; the coconut oil had an acid value of 0.1 mg KOH / g and an iodine value of 11 g I2 / 100 g.

[0031] Preparation of ZAG complex: Take 100g sodium alginate and add 18.6g sodium periodate (sodium periodate to sodium alginate molar ratio 0.15:1), oxidize at 30℃ for 2h, and obtain oxidized sodium alginate with 8% aldehyde degree; take 60g oxidized sodium alginate and 10g ε-polylysine (mass ratio 6:1), react at 45℃ and pH 7.5 (adjusted with 0.1mol / L sodium carbonate solution) for 3h to complete the Schiff base reaction, and obtain the graft copolymer; take 100g graft copolymer and 10g zirconium oxychloride (mass ratio 10:1), react at 30℃ and pH 5.0 (adjusted with 0.1mol / L sodium hydroxide solution) for 1.5h to complete the coordination crosslinking, and obtain ZAG complex (particle size 100nm, crosslinking degree 40%).

[0032] The total mass of the cat litter granules is 1000g (890g core layer + 77g middle layer + 33g outer layer), with a total particle size of 3.5mm and a D50 of 2.8mm. By total mass, the core layer accounts for 89% of the total mass, the middle layer accounts for 7.7% of the total mass, and the outer layer accounts for 3.3% of the total mass.

[0033] Comparative Example 1 The difference between this comparative example and Example 1 is that the intermediate layer is removed, and the outer layer directly coats the outer surface of the core layer. The remaining components, parameters, and preparation methods are completely consistent with those of Example 1.

[0034] Comparative Example 2 The difference between this comparative example and Example 2 is that the ZAG complex in the outer layer is replaced with an equal amount of sodium alginate, while the remaining components, parameters and preparation methods are completely consistent with Example 2.

[0035] Comparative Example 3 The difference between this comparative example and Example 2 is that sodium bicarbonate in the outer layer is removed, while the remaining components, parameters and preparation methods are completely consistent with Example 2.

[0036] Comparative Example 4 The difference between this comparative example and Example 3 is that the olive pit particles in the core layer are replaced with an equal amount of ordinary quartz sand particles (particle size 1.5–3.0 mm), while the remaining components, parameters and preparation methods are completely consistent with Example 3.

[0037] Comparative Example 5 The difference between this comparative example and Example 1 is that zeolite powder is removed from the intermediate layer, and only guar gum and sodium carboxymethyl cellulose (the mass ratio of the two is maintained at 3:2) are retained. The remaining components, parameters and preparation methods are completely consistent with those of Example 1.

[0038] (I) Water Absorption Test: For each of Examples 1-3 and Comparative Examples 1-5, take 10g of sample (accurate to 0.01g), place it in a 200-mesh nylon mesh bag, immerse it in distilled water at 25℃, soak for 30min, then lift it out and drain for 2min, and weigh it. Calculate the water absorption rate. The formula is as follows: (II) Breakage Rate Test: For each of Examples 1-3 and Comparative Examples 1-5, take 200g of sample and place it in a drum abrasion tester. Rotate at 50r / min for 30min. After removal, pass the sample through a 1.0mm standard sieve and weigh the amount of material passing through the sieve. Calculate the breakage rate. The formula is as follows: (III) Ammonia Adsorption / Removal Rate Test: 10 mL of 1% ammonia solution was placed in a sealed 2L desiccator. After the ammonia concentration stabilized at 100 ppm, 50 g of cat litter sample was added. The ammonia concentration was recorded every 30 minutes using an ammonia detector for 4 hours. The final ammonia removal rate was calculated.

[0039] (IV) Antibacterial rate test: Refer to GB / T 21510-2024 "Test Methods and Evaluation of Antibacterial Properties of Nano-Inorganic Materials". Escherichia coli and Staphylococcus aureus were used as test bacteria. 1g of sample was added to the bacterial suspension, shaken, and cultured for 24 hours. The number of viable bacteria was then determined. The antibacterial rate was calculated.

[0040] The results are shown in Table 1: Table 1. Performance test results of Examples 1-3 and Comparative Examples 1-5 As shown in Table 1, the water absorption rates of Examples 1-3 reached 187%, 198%, and 206%, respectively, exhibiting a trend of gradually increasing water absorption rate as the porosity of the olive pit particles increased (from 45% to 55%) and the synergistic effect of each layer component was optimized. The abundant natural pores and capillary structure inside the core layer olive pit particles constitute the first physical adsorption barrier, which can quickly absorb liquid; the middle layer guar gum and sodium carboxymethyl cellulose form a dense water-absorbing gel network, which quickly swells and locks in water upon contact; the outer ZAG complex also helps with water absorption, and the combined effect of the multi-layer structure results in good water absorption.

[0041] In Comparative Example 1, the water absorption rate decreased to 162% after the middle layer was removed. The hydrogel network of the middle layer plays an important role in water absorption and retention; its removal reduced the overall water absorption capacity.

[0042] Comparative Example 2 replaced the outer ZAG complex with an equal amount of sodium alginate, and the water absorption rate did not change much (184%), indicating that sodium alginate itself has a certain water absorption capacity, but the contribution of other components in the ZAG complex to the improvement of water absorption rate is relatively limited. However, the ZAG complex has important significance in the overall performance synergy.

[0043] In Comparative Example 3, removing the outer layer of sodium bicarbonate did not significantly affect the water absorption rate (196%), indicating that sodium bicarbonate has little effect on water absorption and its main function may be to regulate pH and synergistically inhibit bacteria.

[0044] In Comparative Example 4, replacing the core layer of olive pit particles with ordinary quartz sand particles significantly reduced the water absorption rate to 54%. Ordinary quartz sand particles lack the abundant natural channels and capillary structures inside olive pit particles, making them unable to effectively and quickly absorb liquids, resulting in a significant reduction in the overall water absorption rate.

[0045] In Comparative Example 5, the water absorption rate decreased slightly (179%) after zeolite powder was removed from the middle layer. Although the main function of zeolite powder is to adsorb polar odor molecules, it may also play a certain auxiliary role in the overall water absorption performance in the middle layer structure.

[0046] The breakage rates of Examples 1-3 were 2.8%, 2.1%, and 1.6%, respectively. With proper control of the moisture content of the olive pit particles in the core layer (8-10%) and a breakage rate not exceeding 5%, and with the continuous coating of the middle and outer layers forming a smooth and dense surface, the risk of dust generation due to friction between particles was reduced, resulting in a gradual decrease in the breakage rate.

[0047] In Comparative Example 1, the breakage rate increased to 7.5% after the intermediate layer was removed. The intermediate layer covers the outer surface of the core layer, providing some protection and reinforcement. After removal, the core layer particles are more likely to break during the wear process.

[0048] Comparative Example 2 replaced the outer ZAG complex with an equal amount of sodium alginate, and the breakage rate did not change much (2.4%), indicating that the components in the outer ZAG complex other than sodium alginate have little effect on the breakage rate. The overall structure of the outer layer mainly controls the breakage rate by its compactness and smoothness.

[0049] In Comparative Example 3, removing the outer layer of sodium bicarbonate did not significantly change the breakage rate (2.2%), indicating that sodium bicarbonate had no significant effect on the breakage rate.

[0050] In Comparative Example 4, the core layer of olive pit particles was replaced with ordinary quartz sand particles, and the breakage rate increased to 5.9%. Ordinary quartz sand particles may not have the same mechanical strength and wear resistance as olive pit particles, making them more prone to breakage in abrasion tests.

[0051] In Comparative Example 5, the breakage rate increased slightly (3.0%) after zeolite powder was removed from the middle layer. Zeolite powder in the middle layer may have contributed to the stability of the overall structure. After removal, the structural stability decreased slightly and the breakage rate increased.

[0052] The ammonia removal rates in Examples 1-3 reached 88.5%, 91.2%, and 93.8%, respectively, showing a gradually increasing trend. The microporous structure and cation exchange properties of the intermediate zeolite powder can effectively adsorb polar odor molecules such as ammonia, and the ammonia removal effect is even better as the synergistic effect of each layer component is optimized.

[0053] In Comparative Example 1, the ammonia removal rate dropped to 71.4% after the intermediate layer was removed. The zeolite powder in the intermediate layer plays a key role in ammonia adsorption; the removal of the intermediate layer resulted in the lack of this effective adsorption component, leading to a significant decrease in the ammonia removal rate.

[0054] In Comparative Example 2, replacing the outer ZAG complex with an equal amount of sodium alginate reduced the ammonia removal rate to 86.3%. The components in the ZAG complex may have a synergistic promoting effect on ammonia adsorption; however, this synergistic effect weakened after replacement, leading to a decrease in the ammonia removal rate.

[0055] In Comparative Example 3, the removal of the outer layer of sodium bicarbonate reduced the ammonia removal rate to 74.6%. Sodium bicarbonate can slowly release carbon dioxide when it comes into contact with water or in a humid environment, forming a slightly alkaline environment locally. This environment synergistically enhances the adsorption and removal of ammonia with the middle layer components. After removal, the synergistic effect disappears, and the ammonia removal rate decreases.

[0056] In Comparative Example 4, replacing the core layer olive pit particles with ordinary quartz sand particles reduced the ammonia removal rate to 69.2%. Ordinary quartz sand particles lack the structural and compositional advantages of olive pit particles and cannot effectively cooperate with the middle and outer layers for ammonia adsorption, resulting in a significant decrease in the ammonia removal rate.

[0057] In Comparative Example 5, the removal of zeolite powder from the intermediate layer reduced the ammonia removal rate to 76.5%. Zeolite powder is the main component of the intermediate layer that adsorbs ammonia; its removal significantly reduced the ammonia adsorption capacity. Although guar gum and sodium carboxymethyl cellulose may have some auxiliary adsorption effects, the overall ammonia removal rate was significantly reduced.

[0058] Examples 1-3 showed high inhibition rates against *Escherichia coli* and *Staphylococcus aureus*, ranging from 96.2% to 98.3% and 95.8% to 97.5%, respectively. The ε-polylysine in the outer ZAG complex is a broad-spectrum antimicrobial peptide. It is grafted onto the sodium alginate molecular chain via a Schiff base reaction, and then cross-linked by zirconium ions to form a stable cross-linked network. This network effectively encapsulates and slowly releases ε-polylysine, allowing it to be continuously released during cat litter use, thus providing long-term inhibition of bacterial growth.

[0059] In Comparative Example 1, the inhibition rates against Escherichia coli and Staphylococcus aureus decreased slightly after the intermediate layer was removed (94.1% and 93.5%, respectively). The intermediate layer may have some influence on the overall structure and component distribution, indirectly affecting the antibacterial effect, but the impact is relatively small.

[0060] In Comparative Example 2, replacing the outer ZAG complex with an equal amount of sodium alginate significantly reduced the antibacterial rates against Escherichia coli and Staphylococcus aureus to 52.6% and 48.9%, respectively. ε-polylysine in the ZAG complex is the main antibacterial component; the replacement resulted in the loss of this key antibacterial component, leading to a significant decrease in the antibacterial rate.

[0061] In Comparative Example 3, removing the outer layer of sodium bicarbonate did not significantly affect the antibacterial rates against Escherichia coli and Staphylococcus aureus (96.8% and 96.1%, respectively). This indicates that sodium bicarbonate has no significant direct effect on the antibacterial rate; its main role is indirect, such as regulating pH and synergistically enhancing the antibacterial effects of other components.

[0062] Comparative Example 4 showed little change in the inhibition rates against Escherichia coli and Staphylococcus aureus (97.1% and 96.4%, respectively) when the core layer olive pit particles were replaced with ordinary quartz sand particles. This indicates that the composition of the core layer particles has little impact on the inhibition rate, and the inhibition mainly depends on the outer ZAG complex and other components.

[0063] In Comparative Example 5, the removal of zeolite powder from the intermediate layer slightly reduced the antibacterial rates against Escherichia coli and Staphylococcus aureus (95.5% and 94.9%, respectively). Zeolite powder may have some influence on the overall structure and composition distribution, indirectly affecting the antibacterial effect, but the degree of influence is relatively limited.

[0064] In summary, the multi-layered coated olive pit cat litter granules provided by this invention achieve significant improvements in overall performance across multiple dimensions, including water absorption, breakage resistance, deodorization, and antibacterial properties, through the synergistic cooperation of the core layer, middle layer, and outer layer. The core layer utilizes the abundant natural pores and capillary structure of olive pit residue to construct the physical basis for rapid water absorption. The middle layer forms a dense water-absorbing gel network through guar gum and sodium carboxymethyl cellulose, achieving rapid swelling and water retention upon contact with water. Simultaneously, the microporous adsorption and ion exchange properties of zeolite powder effectively remove ammonia. The outer layer, through the broad-spectrum antibacterial effect of ε-polylysine in the ZAG complex and the stable slow-release system formed by zirconium ion coordination cross-linking, endows the material with long-lasting antibacterial capabilities. Furthermore, sodium bicarbonate releases carbon dioxide in humid environments, synergistically enhancing the ammonia removal effect with the zeolite powder.

[0065] In the description of this specification, the reference to terms such as "embodiment," "various embodiments," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or preparation example is included in at least one embodiment of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0066] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A multi-layered coated structure olivastone cat litter particle, characterized in that, include: The core layer comprises olive pit particles with a particle size of 1.5–3.0 mm; An intermediate layer, which covers the outer surface of the core layer, comprises guar gum, sodium carboxymethyl cellulose, and zeolite powder; An outer layer, which covers the outer surface of the intermediate layer, comprises a ZAG complex, sodium bicarbonate, vegetable oil, and a surfactant; The ZAG complex is a complex formed by oxidative grafting of sodium alginate with ε-polylysine and then coordinating and crosslinking it with zirconium ions.

2. The multi-layered coated structure olivelle cat litter particles according to claim 1, wherein, Based on the total mass of cat litter granules, the core layer has a mass fraction of 85–90%, the middle layer has a mass fraction of 6–9%, and the outer layer has a mass fraction of 1.7–3.3%.

3. The multi-layered coated structure olivelle cat litter particles according to claim 1, wherein, In the intermediate layer, the mass ratio of guar gum, sodium carboxymethyl cellulose and zeolite powder is (3–4):(2–3):(1–2).

4. The multi-layered coated structure olivelle cat litter particles of claim 1, wherein, In the outer layer, the mass ratio of ZAG complex, sodium bicarbonate, vegetable oil and surfactant is (0.8–1.2):(0.5–1.0):(0.3–0.8):(0.1–0.3).

5. The multi-layered coated olive pit cat litter granules according to claim 1, characterized in that, The vegetable oil is coconut oil, and the surfactant is an alkyl glycoside.

6. The multi-layered coated olive pit cat litter granules according to claim 1, characterized in that, The ZAG complex was prepared by the following method: sodium alginate was oxidized with sodium periodate to achieve an aldehyde degree of 5–8% to obtain oxidized sodium alginate; the oxidized sodium alginate was reacted with ε-polylysine in a Schiff base reaction to obtain a graft copolymer; and the graft copolymer was then crosslinked with zirconium oxychloride under pH 4.5–5.0 conditions to obtain the final product.

7. The multi-layered coated olive pit cat litter granules according to claim 1, characterized in that, The thickness of the intermediate layer is 0.15–0.30 mm, the thickness of the outer layer is 0.05–0.12 mm, and the total particle size of the multi-layered coated olive pit cat litter particles is 1.8–3.5 mm.

8. The multi-layered coated olive pit cat litter granules according to claim 6, characterized in that, The Schiff base reaction conditions are as follows: the mass ratio of sodium alginate oxide to ε-polylysine is (4–6):1, the reaction temperature is 35–45℃, the reaction time is 2–3h, and the pH of the reaction system is 7.0–7.5; in the coordination crosslinking reaction, the mass ratio of the graft copolymer to zirconium oxychloride is (8–10):1, the reaction time is 1–1.5h, and the reaction temperature is 25–30℃.

9. The multi-layered coated olive pit cat litter granules according to claim 1, characterized in that, The olive pit particles in the core layer are obtained by crushing and screening olive pit residue. The moisture content of the olive pit particles is 8-10%, the total content of lignin and cellulose is 30-40%, the porosity is 45-55%, the water absorption rate is not less than 120% of its own weight, and the breakage rate is not more than 5%.

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