Lithium bentonite / porous silica gel composite cat litter and preparation process thereof

Abstract

The present application provides a kind of lithium-based bentonite / porous silica gel composite cat litter and its preparation process, the composite cat litter includes lithium-based bentonite and porous silica gel, porous silica gel is distributed in lithium-based bentonite microparticle and between microparticle, and form chemical bond with lithium-based bentonite, make microparticle stick together and form larger particle, porous silica gel distribution in lithium-based bentonite can play the role of reinforcing fiber, so that lithium-based bentonite particle strength is enhanced;With lithium-based bentonite, water glass and FeCl3 as main raw material is obtained.The lithium-based bentonite / porous silica gel composite cat litter of the present application, while retaining the advantages of bentonite cat litter such as fast water absorption, large water absorption, good balling property, successfully overcomes the weaknesses of bentonite cat litter such as low strength, large dust and poor deodorization ability, improves the use effect of cat litter, is a bentonite cat litter product with basically no obvious performance defects, and has wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of cat litter technology, specifically relating to a lithium-based bentonite / porous silica gel composite cat litter and its preparation process. Background Technology

[0002] Cat litter, also known as pet bedding, is an inorganic absorbent material used to remove pet feces and odors, thus maintaining indoor hygiene. Inorganic minerals that can be used as pet bedding (cat litter) include sepiolite, bentonite, diatomaceous earth, and attapulgite. With the improvement of living standards in my country and the increasing prevalence of high-rise buildings and gardens in urban areas, the use of pet bedding is growing, and the market for pet cat litter is expected to expand significantly.

[0003] The main indicators for evaluating the quality of cat litter products are absorbency, clumping ability, dust content, and odor control. The clumping ability of cat litter is closely related to its absorbency, which includes two important indicators: absorption speed and absorption capacity. Cat litter with fast absorption and high absorption capacity per unit mass has superior clumping ability. To ensure its clumping and absorption effects, cat litter particles are usually very fine. Such litter easily adheres to the pet's fur and paw crevices and spreads with the pet. More seriously, these fine litter particles can generate a large amount of dust, polluting indoor air and human health. The simplest way to solve the dust problem is to produce larger-particle strips or balls of cat litter. However, large-particle litter can also cause urine to not be completely absorbed due to the larger gaps between the particles, resulting in urine flowing to the bottom of the litter box.

[0004] Eliminating cat litter dust can also be achieved by adding binders. Patent CN111937757A provides a small-particle bentonite cat litter that uses water glass as a binder to prevent dust generation. Patent CN112400709A involves pulverizing and premixing sodium bentonite and modified zeolite together, then adding water glass for binding and granulation; the added water glass also serves as a binder and dust preventer. However, this method of dust removal using external binders often significantly reduces the water absorption and adsorption properties of bentonite and other materials, deteriorating the performance of the cat litter.

[0005] Poor odor control is also a common problem with bentonite cat litter products. Cat litter manufacturers typically address this by adding solid adsorbents such as silica gel, activated carbon, molecular sieves, and zeolite. However, adding these adsorbents reduces the litter's absorbency and clumping properties, and these adsorbents are generally expensive, increasing production costs. Therefore, producing cat litter that is fast-absorbing, has high absorbency, high strength, and strong odor control requires a comprehensive balance of various factors.

[0006] Currently, there are many types of cat litter on the market, including five main categories: regular cat litter, clumping cat litter, crystal cat litter, wood powder cat litter, and paper litter. While some products offer good results, others are expensive, limiting their widespread use. Cheaper options are less effective, while more effective options are too pricey, restricting market penetration. Bentonite clumping cat litter is currently the most widely used type. It has strong absorbency, good clumping properties, and is the cheapest option. It quickly absorbs moisture and urine from feces, clumping it into clumps for easy cleaning. However, the common weaknesses of cat litter also represent significant drawbacks of bentonite cat litter, which must be addressed to improve its performance. One drawback of bentonite cat litter is its poor granule strength. During production and use, it easily breaks into small particles that adhere to cat fur and paws. These small bentonite cat litter particles also generate a large amount of dust, causing dust accumulation on indoor furniture and air pollution. The second drawback is that bentonite cat litter has poor deodorizing ability. It often requires the addition of zeolite, silica gel, and other components to act as deodorizing agents to improve its odor-removing performance, but this also results in a loss of water absorption and clumping ability. These are problems that must be addressed to improve and perfect the performance of bentonite cat litter. Summary of the Invention

[0007] To overcome two shortcomings in the performance of bentonite cat litter in the prior art, this invention provides a lithium-based bentonite / porous silica gel composite cat litter and its preparation process. The lithium-based bentonite / porous silica gel composite cat litter comprises lithium-based bentonite and porous silica gel. The porous silica gel is distributed within and between lithium-based bentonite particles and forms chemical bonds with the surface of the lithium-based bentonite particles, causing the lithium-based bentonite particles to adhere and form larger particles. The porous silica gel distributed in the lithium-based bentonite acts like reinforcing fibers, strengthening the strength of the lithium-based bentonite particles. The porous silica gel accounts for a small proportion, ranging from approximately 2% to 4% by mass, but its distribution in the lithium-based bentonite effectively reinforces the particles. The lithium-based bentonite / porous silica gel composite cat litter prepared in this way has high particle strength, is not easily broken, has very little dust, absorbs water quickly and has a large water capacity, and also exhibits outstanding deodorizing performance.

[0008] This invention also provides a novel preparation process for lithium-based bentonite / porous silica gel composite cat litter, comprising mixing lithium-based bentonite with a water glass solution, wherein the water glass is distributed on the surface and between the lithium-based bentonite particles, and then adding an aqueous FeCl3 solution to react and obtain a lithium-based bentonite / silicic acid hydrogel composite, followed by aging, drying, and high-temperature activation to obtain the lithium-based bentonite / porous silica gel composite cat litter. The water glass undergoes a chemical change to transform into a porous silica gel with adsorption function and a certain strength. These porous silica gels are distributed within and between the lithium-based bentonite particles, binding these small particles together to form larger particles with enhanced strength.

[0009] The preparation of the lithium-based bentonite / silicic acid hydrogel composite preferably includes the following steps:

[0010] S1 Lithium-based bentonite is sprayed with water glass and extruded: Lithium-based bentonite is fed into a double-roller extruder, water glass solution is sprayed in, and then the double-roller extrusion is performed to form a mixture of the two.

[0011] S2 mixture is sprayed with FeCl3 aqueous solution and extruded: FeCl3 aqueous solution is sprayed into the mixture and then extruded by rollers. During this process, the water glass in the mixture reacts immediately upon contact with FeCl3 to generate silicic acid. Since silicic acid is unstable, it automatically polymerizes into polysilicic acid, which further forms silicic acid hydrogel. Therefore, this process yields a lithium-based bentonite / silicic acid hydrogel composite.

[0012] A high proportion of water glass in the sprayed solution is beneficial for forming more porous silica gel and improving the strength of lithium-based bentonite cat litter particles. However, it also affects the water absorption and clumping properties of lithium-based bentonite, causing a decrease in these two properties. Considering factors such as cat litter particle strength, water absorption rate, and deodorization, the preferred method is to spray a water glass solution at a mass of 8-10% of the anhydrous lithium-based bentonite mass. The water glass solution has a modulus of 3.3-3.4 and a specific gravity of 1.18-1.19 g / cm³. 3 The spray concentration is 20% (the mass ratio of water glass to water is 1:4).

[0013] Preferably, the concentration of the FeCl3 aqueous solution is 14-16%, and the injection amount is 8-10% of the mass of anhydrous lithium-based bentonite.

[0014] Over time, the silica hydrogel continues to undergo linear and branched condensation at the Si-O-Si bond level, forming a porous silica gel. After a certain period of aging, the silica gel loses its toughness and forms a rigid framework structure, resulting in a brittle, hydrated silica gel. Since the silica gel initially formed from water glass is a highly hydrated gel, it needs to age to transform from an elastic state to a rigid or brittle state with a certain strength. Furthermore, the aging process is endothermic; if the temperature is too low, it will take a very long time to complete. Therefore, preferably, the aging temperature is 25℃~45℃, and the aging time is 24h~72h.

[0015] Preferably, the aging process is stacking aging.

[0016] The aged hydrous silica gel is dried at low temperature to remove non-structural water and some structural water from the brittle hydrous silica gel, reducing the water content to 40-50%. This causes the silica gel pores to shrink, the volume to decrease, and the strength to increase, resulting in a reinforced silica gel. The preferred low-temperature drying temperature is 100°C.

[0017] The silica gel, after low-temperature drying, needs to be activated at high temperature to remove structural water, forming a porous silica gel with further increased strength. This yields a lithium-based bentonite / porous silica gel composite cat litter. The high-temperature activation temperature is 200–350°C, which ensures that all the water glass forms a porous silica gel while preventing damage to the coexisting lithium-based bentonite structure. Further, a high-temperature activation temperature of 300°C is preferred.

[0018] Preferably, the process also includes sieving and sealing packaging: the above-mentioned lithium-based bentonite / porous silica gel composite cat litter is sieved to obtain 0.3-3mm particles and then sealed and packaged.

[0019] The preferred method for preparing lithium-based bentonite includes feeding calcium-based bentonite powder into a double-roll extruder while simultaneously spraying in an aqueous lithium carbonate solution, performing extrusion two or more times consecutively, followed by aging. During the first extrusion by the double-roll extruder, the layered structure of the calcium-based bentonite is broken up and peeled off, exposing as many crystal layers as possible. Simultaneously, an aqueous lithium carbonate solution is sprayed in, partially exfoliating the Li-based bentonite. + Ca on the surface of exposed bentonite crystal layers 2+ An exchange reaction occurs, and some Li + Infiltrates into the interlayer domains of the bentonite stratified structure and interacts with the Ca in the interlayer domains. 2+ Ion exchange forms lithium-based bentonite; the material modified by extrusion and peeling in the first double-roll mill continuously enters the subsequent double-roll mill for further extrusion and peeling, as well as Li... + With Ca 2+ The exchange modification reaction.

[0020] Preferably, the calcium-based bentonite is obtained by drying, pulverizing, and desanding natural calcium-based bentonite. Further, the pulverizing and desanding are performed using a Raymond mill to pulverize the calcium-based bentonite while simultaneously removing sand, thereby purifying the calcium-based bentonite.

[0021] The aging time is 30 days or more. The material, after being extruded and peeled by two or more roller mills to achieve sufficient lithiation modification, undergoes further aging for at least 30 days to obtain lithium-based bentonite, thus enabling Li... + With Ca 2+ Ions are fully exchanged.

[0022] The aging process refers to the process of aging through stacking.

[0023] The lithium carbonate aqueous solution has a concentration of 10%, and the injected mass is 4% of the dry-based lithium-based bentonite mass.

[0024] The silica gel obtained by the above production process from water glass has high hardness, which can improve the strength of lithium-based bentonite particles. It also possesses well-developed pores with channel diameters of 0.3–1 nm, while NH4… + The ion has a diameter of 0.286 nm, which is just right for NH4.+ And the adsorption of low-molecular-weight organic matter.

[0025] The reason why lithium-based bentonite is chosen as the main agent of cat litter in this invention is that lithium-based bentonite has a higher water absorption capacity than sodium-based and calcium-based bentonite, and more importantly, it has a stronger ability to remove pet feces odor than calcium-based and sodium-based bentonite.

[0026] Montmorillonite, the main component of bentonite, belongs to the monoclinic crystal system. Its basic building blocks are silicon-oxygen tetrahedra and aluminum-oxygen octahedra, and it is characterized by its tendency to undergo isomorphous substitution. This is the fundamental structural characteristic of montmorillonite, where some low-valence cations in the crystal lattice replace high-valence cations, such as Si in the silicon-oxygen tetrahedra. 4+ Can be Al 3+ Fe 3+ Replacement, Al in aluminum octahedron 3+ Can be Mg 2+ Fe 2+ Zn 2+ This lattice substitution results in a positive charge depletion, causing the structural units of montmorillonite to acquire a permanent negative charge. To achieve charge balance, Na+ needs to be adsorbed between the layers. + K + Ca 2+ Mg 2+ The cations exchanged between the montmorillonite crystal layers balance these negative charges. The binding force between these cations and the montmorillonite crystals is primarily electrostatic attraction, and this binding force depends mainly on two factors: the structural position of the adsorbed cations within the montmorillonite mineral and the valence state of the cations. Higher valence states result in greater charge, stronger binding force with the montmorillonite lattice, and a greater ability to displace other cations. At equivalent valence states, smaller cation radii and higher charge densities also lead to stronger binding force with the montmorillonite lattice and a greater ability to displace other cations. At the same ion concentration, ions with stronger binding force to the montmorillonite lattice have a greater ability to displace other cations. Of course, at sufficiently high concentrations, lower-valence cations can also displace higher-valence cations.

[0027] Chemical thermodynamic studies have shown that Li + The binding energy with the montmorillonite lattice is approximately 1.26–1.68 kJ / mol, Na + K + Approximately 4.20 kJ / mol, Ca 2+ Mg 2+ and NH4 + Approximately 8.40–12.60 kJ. This is precisely due to Li… +Among all cations, it has the lowest binding energy with the montmorillonite lattice and the worst exchange capacity. Therefore, under the same conditions, all other cations, including neutral organic matter, can easily displace it from the montmorillonite interlayer. This also indirectly explains why lithium-based bentonite can swell and disperse in both water and oil.

[0028] Based on the binding energy between the cation and the montmorillonite lattice, the order of several common cation exchange capacities can be obtained as follows:

[0029] Al 3+ >Ba 2+ >Ca 2+ ≥Mg 2+ ≥NH4 + >H + >K + >Na + >Li +

[0030] Li + Among all cations, lithium-based bentonite has the lowest binding energy to the montmorillonite lattice, the weakest exchange capacity, and is most easily exchanged from the montmorillonite lattice by other cations. This invention uses lithium-based bentonite as the main component of cat litter. Under normal dietary conditions, the pH of pet urine is 4.3–8.0, with an average of 5.7, indicating a slightly acidic environment. The ammonia nitrogen in this urine is expressed as NH4+. + As can be seen from the order of cation exchange capacity mentioned above, NH4 in pet feces exists in ionic form. + It is easy to separate the Li between the lithium-based bentonite layers. + Ions are exchanged out, while NH4+ is released. + It enters the interlayer of montmorillonite crystals and is fixed there, thereby achieving the purpose of removing ammonia odor from lithium-based bentonite cat litter.

[0031] Although cat litter product developers often only discuss ammonia removal when addressing odor control in cat litter, the reality is that ammonia is only one factor contributing to the odor of pet feces. Pet feces is an extremely complex aqueous system containing ammonia nitrogen, organic amines, organic sulfur, urea, formic acid, acetic acid, acetaldehyde, and other substances. These organic compounds are often highly volatile and have a stronger odor; simply removing ammonia cannot completely eliminate the odor of pet feces. As mentioned above, due to Li + Among all cations, Li has the lowest binding energy with the montmorillonite lattice and is the most easily exchanged. Under the same conditions, Li + All other cations besides ions, including many neutral organic compounds, can readily displace it from the interlayer of montmorillonite. This means that low-molecular-weight organic compounds in pet feces can also enter the interlayer of lithium-based bentonite and interact with Li. + Ion exchange occurs, therefore lithium-based bentonite absorbs water and NH4+. +While ionizing, it can also absorb other organic compounds in pet feces to further remove the odor of pet feces.

[0032] While lithium-based bentonite cat litter boasts numerous advantages such as rapid water absorption, high water capacity, and efficient odor removal, it also suffers from weaknesses including low particle strength, brittleness, and dust generation. This invention utilizes a composite of water glass and lithium-based bentonite to obtain a lithium-based bentonite / porous silica gel composite cat litter. Water glass is used as a particle reinforcing agent, forming porous silica gel within and between lithium-based bentonite particles and establishing chemical bonds with the bentonite. This causes the particles to adhere and form larger particles. By leveraging the adhesive properties of water glass and the strength of the silica gel after conversion, as well as the interaction between the silica gel and lithium-based bentonite, the strength of the lithium-based bentonite particles is enhanced. This significantly improves the strength of the lithium-based bentonite cat litter particles, substantially reduces dust generation, and overcomes the weakness of easy pulverization.

[0033] Another function of water glass in this invention is to transform it into porous silica gel under appropriate conditions. Porous silica gel not only enhances the strength of lithium-based bentonite particles, but is also an excellent solid adsorbent. When combined in the cat litter of this invention, it can also play the role of water absorption and deodorization, thus increasing the adsorption function of this cat litter.

[0034] Silica gel is a non-toxic and odorless amorphous substance, a highly active porous adsorbent material produced from water glass through chemical reactions and a series of subsequent treatments. Its main component is silicon dioxide, which has a tetrahedral structure with silicon atoms at the center and oxygen atoms at the vertices. The main structure of silica gel is composed of these irregularly stacked tetrahedra. The presence of numerous silanol groups (Si-OH) on the surface of silica gel provides the basis for its adsorption properties. Silica gel exhibits good mechanical strength, chemical stability, high specific surface area and adsorption capacity, and its specific surface area and pore structure are relatively easy to control. Therefore, it is widely used in many fields and is one of the most common inorganic solid adsorbents.

[0035] The transformation of water glass into porous silica gel is essential and beneficial in this invention. Without this transformation, although water glass has a binding effect on lithium-based bentonite particles, and this binding (or covering) effect is stronger, it will encapsulate the lithium-based bentonite particles, thus affecting their water absorption and adsorption capabilities. However, in this invention, by transforming water glass into porous silica gel, the xH2O and Na2O in the Na2O.3SiO2.xH2O molecules are either evaporated at high temperatures or transformed into soluble sodium chloride, leaving only 3SiO2 to form a porous silica gel. During the formation process, these porous silica gels can be dispersed within lithium-based bentonite, acting as "reinforcing fibers" to strengthen it. On the surface of the particles, due to surface tension and capillary forces, most of them are concentrated between the lithium-based bentonite particles, binding them together to form large cat litter particles. All of these factors enhance the strength of the lithium-based bentonite / porous silica gel composite cat litter prepared using this process. At the same time, because the porous silica gel has a relatively small mass, it does not significantly reduce the water absorption performance of the lithium-based bentonite.

[0036] The beneficial effects of this invention are as follows:

[0037] This invention uses natural calcium-based bentonite, lithium carbonate, water glass, and FeCl3 as main raw materials to prepare lithium-based bentonite / porous silica gel composite cat litter. While retaining the advantages of bentonite cat litter, such as rapid water absorption, high water capacity, and good clumping properties, it successfully overcomes the weaknesses of bentonite cat litter, such as low strength, high dust content, and poor deodorization ability. This makes the lithium-based bentonite / porous silica gel composite cat litter of this invention a bentonite cat litter product with virtually no significant performance defects. The technical innovations of this invention are as follows:

[0038] 1. Porous silica gel is prepared by decomposing water glass with FeCl3. During the formation of porous silica gel, lithium-based bentonite particles are also bonded together. They are distributed inside and between lithium-based bentonite particles, which greatly improves the strength of lithium-based bentonite cat litter particles and effectively solves the problems of bentonite cat litter being fragile and dusty.

[0039] 2. In this invention, the porous silica gel prepared from FeCl3 gel water glass not only enhances the strength of lithium-based bentonite cat litter particles, but also possesses strong adsorption capacity. Furthermore, it exhibits more developed pores and slightly larger pore diameters than silica gels made from acid-based gel water glass, with pore diameters reaching 0.3–1 nm, which is perfectly suited for NH4 with a diameter of 0.286 nm. + Adsorption and removal of ions and low-molecular-weight organic compounds such as organic amines of the same diameter.

[0040] 3. This invention uses lithium-based bentonite instead of the most common sodium-based or calcium-based bentonite as the main agent in cat litter, based on the presence of NH4 in pet feces. + Li-ion exchanged lithium-based montmorillonite+ Ion exchange ratio of Na in sodium-based bentonite or calcium-based bentonite + or Ca 2+ The reaction of ions is easier to carry out because Li... + Of all cations, ions are the most easily exchanged, and Na+ is the most readily exchanged. + Ion exchange is more than twice as difficult as it is, Ca 2+ Ion exchange is more than four times more difficult. Therefore, lithium-based bentonite has a stronger ability to remove ammonia odor than sodium-based and calcium-based bentonite, and lithium-based bentonite cat litter is more effective at eliminating the ammonia odor from pet feces.

[0041] 4. NH4 is not the only cause of the odor in pet feces. + -N, but also contains numerous low-molecular-weight organic compounds such as organic amines and organic sulfur, which have an even stronger odor; removing only the ammonia odor leaves the fecal odor difficult to eliminate. Li + The ions have the lowest binding energy to the montmorillonite lattice, and it can swell in both water and organic solvents, indicating that polar water molecules can enter its interlayer space, as can nonpolar or weakly polar organic molecules. Therefore, this invention uses lithium-based bentonite, which can also bind with many odorous organic compounds in pet feces. + It undergoes an ion exchange reaction and enters the interlayer of montmorillonite crystals, where it is fixed and loses its volatility, further eliminating the odor of pet feces.

[0042] 5. Lithium-based bentonite, as the main component of bentonite cat litter in this invention, has a higher water absorption capacity than sodium-based bentonite and calcium-based bentonite, better clumping properties, lower dosage, and longer service life for the same amount of cat litter. It also has the indirect effect of preventing cat litter from sticking to the bottom and sides of the litter box.

[0043] 6. The cat litter product produced using the process of this invention consists of irregular bentonite granules. The granules are smooth and without sharp edges, resulting in high friction between the granules, no dust, and minimal adhesion to pet fur. The small gaps between the granules after accumulation further facilitate clumping and prevent pet urine from leaking to the bottom of the litter box. Detailed Implementation

[0044] Example 1

[0045] Lithium-based bentonite / porous silica gel composite cat litter was prepared using the following process:

[0046] (1) Natural calcium-based bentonite was dried at 110℃ to a moisture content of 12% after sun drying; (2) The sand removal port was appropriately enlarged, and 200-mesh calcium-based bentonite powder was obtained by Raymond milling; (3) The calcium-based bentonite powder was fed into a double-roller extruder, and 10% lithium carbonate aqueous solution was sprayed in at the same time. The sprayed mass was 4% of the mass of calcium-based bentonite based on pure lithium carbonate. The extruder was extruded twice to obtain hydrated lithium-based bentonite, which was then piled up for 30 days; (4) The piled-up hydrated lithium-based bentonite was sprayed with 20% water glass solution. The sprayed mass was 8% of the dry-based lithium-based bentonite mass, and the double-roller extruder was extruded once. Then, 15% ferric chloride solution was sprayed in. 9% of the mass of lithium-based bentonite was extruded again by roller to obtain a lithium-based bentonite and aqueous silica gel composite (lithium-based bentonite / silicic acid hydrogel composite); (5) the lithium-based bentonite and aqueous silica gel mixture was aged at 30°C for 48 hours to obtain brittle aqueous silica gel; (6) the brittle silica gel was dried at 100°C to a water content of 45% to obtain reinforced silica gel; (7) the reinforced silica gel was activated at 300°C to remove all structural water and become a porous silica gel with adsorption activity. The 0.3-3 mm components were collected by sieving to obtain lithium-based bentonite / porous silica gel composite cat litter sample I.

[0047] Example 2

[0048] In Example 1, the mass of water glass sprayed in step (4) was changed to 9% of the mass of dry lithium-based bentonite, while the rest remained the same as in Example 1, thus preparing lithium-based bentonite / porous silica gel composite cat litter sample II.

[0049] Example 3

[0050] In Example 1, the mass of water glass sprayed in step (4) was changed to 10% of the mass of dry lithium-based bentonite, while the rest remained the same as in Example 1, thus preparing lithium-based bentonite / porous silica gel composite cat litter sample III.

[0051] Comparative Example I

[0052] (1) Natural calcium-based bentonite was dried at 110℃ to a moisture content of 12% after sun drying; (2) The sand removal port was appropriately enlarged and Raymond powder was ground to obtain 200 mesh calcium-based bentonite powder; (3) The calcium-based bentonite powder was fed into a double roller extruder and a 10% lithium carbonate aqueous solution was sprayed in at the same time. The sprayed mass was 4% of the mass of calcium-based bentonite based on pure lithium carbonate. The mixture was extruded twice to obtain hydrous lithium-based montmorillonite. After being piled up for 30 days, it was dried at 110℃ to a moisture content of 12%. The sample was collected by sieve with a thickness of 0.3-3 mm to obtain pure lithium-based bentonite cat litter sample.

[0053] Comparative Example II

[0054] Natural calcium-based bentonite cat litter granules with a particle size of 0.3–3 mm and a water content of 12%.

[0055] Comparative Example III

[0056] Red Star brand bentonite cat litter.

[0057] Comparative Example IV

[0058] Except for the step of spraying FeCl3 in step (4) of Example I, the rest is exactly the same. A comparison sample of cat litter in which water glass did not transform into porous silica gel was obtained.

[0059] The methods for testing the quality of cat litter in the examples and comparative cases are as follows:

[0060] 1. Water Absorption Rate: According to GB / T20973-2007 "New Water Absorption Rate Test Method Provided by Porous Plate Method", the specific test steps are as follows: Place the porous ceramic plate in a glass container and immerse it in distilled water until the porous ceramic plate is fully soaked. During the test, always keep the upper surface of the porous ceramic plate 6±1mm above the water surface, and keep the temperature of the glass container and water stable at 20±2℃.

[0061] Soak two sheets of filter paper in distilled water for 30 seconds to saturate them with water, then place them on a porous ceramic plate to equilibrate the water for 60 minutes, and weigh the filter paper separately.

[0062] Weigh out two cat litter samples, each 5 ± 0.01 g, that have been dried to constant weight at 105 ± 3℃. Spread them evenly on two sheets of wet filter paper, with the litter spread in a diameter of approximately 9 cm.

[0063] Place the filter paper and cat litter symmetrically on a porous ceramic plate (be careful not to overlap), and cover with a glass container lid. After standing for 2 hours, carefully remove the wet filter paper and cat litter samples with tweezers and a spatula, and weigh them on a balance.

[0064] The water absorption rate of cat litter is calculated using formula (1):

[0065]

[0066] Where: Wa—water absorption rate, %; W—mass of wet filter paper and wet cat litter, g; W0—mass of wet filter paper, g; m—mass of dry cat litter sample, g.

[0067] Water absorption rate (%) ≥ 200 in 2 hours is acceptable.

[0068] 2. Leakage test: Spread cat litter evenly in the litter box to a fixed thickness of 5cm. Put 50mL of 1% NaCl aqueous solution into a 100mL separatory funnel. At a height of 30cm above the cat litter, drip the solution at a constant rate over 30s. After 120s, check whether the cat litter leaks to the bottom. If it does not leak to the bottom, it is considered qualified.

[0069] 3. Agglomeration strength: Agglomeration shape and agglomeration strength

[0070] Spread the cat litter evenly in a container of 25cm×12cm×8cm (length×width×height); add 10mL of 1% NaCl solution to the cat litter from a height of 2.5cm within 4 to 5 seconds; after 10 seconds, pour out the caked test block, observe the shape of the cake and record it. Let the test block fall freely from a height of 15cm, record whether the test block is broken, and it is qualified if the test block is not broken.

[0071] 4. Deodorization effect test

[0072] Prepare 100mL of a mixed solution of 0.01% dimethylamine and 1% sodium chloride for later use.

[0073] Weigh 2000g of cat litter into a litter box, absorb 20mL of the above solution with a quantitative syringe, inject it into the cat litter at a rate of 1.5mL / s, after 30 minutes, 5 people conduct odor scoring tests respectively, the scoring test and evaluation results are shown in Table 1.

[0074] Table 1 Odor scoring test and evaluation results

[0075]

[0076] The experimental results of the various examples and comparative examples are shown in Table 2.

[0077] Table 2 Comparative experiment results

[0078]

[0079] It can be seen from Table 2 that the lithium-based bentonite / porous silica gel composite cat litter prepared by the process of the present invention in Examples 1 to 3 is generally superior to several comparative examples in terms of dust, water absorption, bottom leakage, caking strength and odor, and several comparative examples all have certain defects in performance.

[0080] Comparative Example I is pure lithium-based bentonite cat litter, the other four indicators are qualified, but the dust is large; Comparative Example II is pure calcium-based bentonite cat litter, with large dust and poor deodorization; Comparative Example III is commercial bentonite cat litter, which also has the disadvantages of large dust and poor deodorization; in Comparative Example IV, since sodium silicate fails to transform into porous silica gel and covers and wraps on the surface of lithium-based bentonite particles, which seriously affects its performance, all technical indicators are poor except for basically no dust.

Claims

1. A preparation process for lithium-based bentonite / porous silica gel composite cat litter, characterized in that: The lithium-based bentonite / porous silica gel composite cat litter comprises lithium-based bentonite and porous silica gel. The porous silica gel is distributed within and between the lithium-based bentonite particles and forms chemical bonds with the surface of the lithium-based bentonite particles, causing the lithium-based bentonite particles to adhere and form larger particles. The porous silica gel distributed in the lithium-based bentonite can act as a reinforcing fiber, thereby strengthening the lithium-based bentonite particles. The mass percentage of porous silica gel in the cat litter is 2-4%. The preparation process of the lithium-based bentonite / porous silica gel composite cat litter includes mixing lithium-based bentonite with water glass solution, then adding FeCl3 aqueous solution to react and obtain lithium-based bentonite / silicic acid hydrogel composite, and then aging, drying and high temperature activation to obtain lithium-based bentonite / porous silica gel composite cat litter. The mass of the added water glass solution is 8-10% of the mass of anhydrous lithium-based bentonite; The modulus of water glass solution is 3.3-3.4, and the specific gravity is 1.18~1.19 g / cm³. 3 The concentration is 20%. The concentration of the FeCl3 aqueous solution is 14-16%, and the amount added is 8-10% of the mass of anhydrous lithium-based bentonite. The aging temperature is 25℃~45℃, and the aging time is 24h~72h. The drying process is low-temperature drying; the high-temperature activation temperature is 200~350℃.

2. The preparation process of lithium-based bentonite / porous silica gel composite cat litter as described in claim 1, characterized in that: The preparation method of the lithium-based bentonite / silicic acid hydrogel composite specifically includes the following steps: S1 Lithium-based bentonite is sprayed with water glass and extruded: Lithium-based bentonite is fed into a double-roller extruder, water glass solution is sprayed in, and then the double-roller extrusion is performed to form a mixture of the two. S2. Spraying FeCl3 aqueous solution into the mixture and extruding: Spraying FeCl3 aqueous solution into the mixture and then extruding it with rollers to obtain lithium-based bentonite / silicic acid hydrogel composite.

3. The preparation process of lithium-based bentonite / porous silica gel composite cat litter as described in claim 1, characterized in that: The method for preparing lithium-based bentonite includes feeding calcium-based bentonite powder into a double-roller extruder, simultaneously spraying in an aqueous lithium carbonate solution, extruding continuously twice or more, and then aging the mixture.

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