A health prompt and odor detection-absorption bifunctional color-changing cat litter and a preparation method thereof

Abstract

The application discloses a health prompt and odor detection-absorption bifunctional color-changing cat litter and a preparation method thereof, and belongs to the technical field of functional materials and pet products. The color-changing cat litter comprises a cat litter base material, an adhesive, a thickening agent and an ammonia gas response type hydrogen bond composite probe. The probe has the advantages of enhanced sensitivity, fast response speed, intuitive color change, ammonia gas absorption and the like. When the cat litter contacts urine, the color of the cat litter changes instantaneously to prompt the pH value of the urine, thereby realizing preliminary early warning of health. Meanwhile, the cat litter can long-effectively monitor the cumulative concentration of ammonia gas and actively adsorb and eliminate the odor. The color of the cat litter gradually changes from yellow to blue with the concentration, thereby directly indicating the sanitary condition of the cat litter and the replacement time. The color-changing cat litter realizes the integration of the chemical signal visual response and the harmful gas active purification function, has the characteristics of intuitive response, green safety, simple preparation process and low cost, and is suitable for large-scale production and application.

Description

Technical Field

[0001] This invention belongs to the field of functional materials and pet supplies technology, specifically relating to a color-changing cat litter with dual functions of health alerts and odor detection-absorption, and its preparation method. Background Technology

[0002] Cat litter is a core consumable for maintaining a hygienic indoor cat-owning environment. As pet owners become more aware of pet health management and have higher requirements for their home environment, users' core demands have evolved from simply "dealing with excrement" to "monitoring pet health through excrement" and "scientifically managing the hygiene of the litter box."

[0003] In existing technologies, some color-changing cat litter products use indicators added to the litter to cause a color change due to pH fluctuations upon contact with urine, thus providing an initial indication of the pet's urinary system health, as illustrated in patent applications CN117502253A and CN117296722A. However, this technology has significant limitations: First, it can only achieve single-point pH detection at the moment of urine contact, failing to track the dynamic accumulation of odors generated by microbial decomposition of excrement during the litter's lifespan, and lacking in-situ odor elimination capabilities. Odor concentration (primarily ammonia) is a key indicator of the litter's hygiene and deodorizing ability. Second, the sensitivity of existing indicator systems is limited, with a delayed and insignificant response to low concentrations of ammonia. Third, the existing products' health indication, hygiene monitoring, and odor removal modules are independent or separate, leading to high production costs and complex processes. Furthermore, it is difficult for a single material to actively improve air quality within the litter box while simultaneously providing indication.

[0004] Therefore, developing a new type of smart color-changing cat litter that can simultaneously meet the functions of real-time early warning of pet health, long-term monitoring of cat litter hygiene, and active odor elimination, and has high sensitivity, intuitive response, and controllable cost, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This invention aims to overcome the aforementioned shortcomings of existing technologies and provide a color-changing cat litter with dual functions of health alerts and odor detection-absorption. This invention constructs an ammonia-responsive hydrogen-bonded composite probe (HRCC composite probe) with an integrated "ammonia enrichment-response" function and uniformly loads it into the cat litter substrate. This converts chemical signals into intuitive color changes, thereby reconstructing and upgrading the cat litter's functionality. This cat litter not only instantly indicates the urine's pH level through color changes during urination (health alert), but also continuously monitors the accumulated concentration of ammonia during use and actively adsorbs and purifies it (hygiene indicator), helping users determine their pet's health status and when to clean the litter.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The HRCC composite probe of this invention is prepared by autocatalytic crosslinking, and the specific steps are as follows: (1) Mix betaine hydrochloride and tetrabutylammonium chloride evenly to obtain a first mixture; mix polyethylene glycol and polyethylene glycol diglycidyl ether evenly to obtain a second mixture; (2) The first mixture and the second mixture are mixed to carry out a crosslinking reaction to obtain a crosslinked polymer matrix; (3) The cross-linked polymer matrix is ​​mixed with a color developer, so that the color developer is embedded in the cross-linked polymer matrix to obtain the ammonia-responsive hydrogen bond composite probe.

[0007] Preferably, in step (1), the betaine hydrochloride and tetrabutylammonium chloride are mixed in a molar ratio of 1:1 to 3:1; and the polyethylene glycol and polyethylene glycol diglycidyl ether are mixed in a molar ratio of 2:1 to 5:1.

[0008] Preferably, in step (2), the first mixture and the second mixture are mixed at a total molar ratio of 1:1 to 1:4; The cross-linking reaction is carried out at a temperature of 40~80℃ for 20~60 min.

[0009] Further, in step (3), the mass ratio of the crosslinked polymer matrix to the color developer is 10:0.05~5; The colorimetric reagent is bromophenol blue; The mixing temperature is the same as the crosslinking reaction temperature in step (2).

[0010] The present invention also provides an ammonia-responsive hydrogen bond composite probe prepared by the above-described preparation method.

[0011] The HRCC composite probe can be diluted with deionized water to prepare a stock solution with a colorimetric reagent concentration of 0.5~50 mg / mL for later use.

[0012] This invention also provides the application of the above-mentioned ammonia-responsive hydrogen bond composite probe in the preparation of a dual-function color-changing cat litter for health alerts and odor detection and absorption.

[0013] Furthermore, during application, as the cumulative concentration of ammonia increases, the color of the cat litter gradually changes from yellow to blue. This achieves the dual functions of immediate urine pH health alerts and long-term hygiene monitoring of cumulative ammonia concentration, and also features active deodorization capabilities, intuitive color changes, high sensitivity, and controllable cost.

[0014] Based on this, the present invention provides a dual-function color-changing cat litter for health alerts and odor detection and absorption, comprising a cat litter substrate, an adhesive, a thickener, and the aforementioned ammonia-responsive hydrogen bond composite probe.

[0015] Furthermore, the cat litter substrate is selected from at least one of tofu residue fiber powder, corn starch, and tapioca starch, accounting for 80% to 95% of the total mass of the cat litter; The binder and thickener are each selected from at least one of guar gum, corn starch, and maltodextrin, and the binder and thickener together account for 5% to 20% of the total mass of the cat litter. The ammonia-responsive hydrogen-bonded composite probe accounts for 0.005% to 0.5% of the total mass of cat litter.

[0016] This invention also provides a method for preparing the above-mentioned dual-function color-changing cat litter with health tips and odor detection and absorption, comprising the following steps: (1) Mix the cat litter base material, adhesive and thickener and water to form a uniform wet cat litter; (2) The ammonia-responsive hydrogen bond composite probe solution is uniformly applied to the wet cat litter and mixed evenly; (3) The material obtained in step (2) is granulated, dried and screened to obtain the dual-function color-changing cat litter.

[0017] The drying temperature is 50~100℃ until the moisture content of the cat litter granules is less than 10%. The finished product with a particle size range of 2 mm is collected to obtain the finished product of the dual-function color-changing cat litter with health tips and odor detection-absorption.

[0018] The response performance characterization method of the HRCC composite probe described in this invention is as follows: 200 μL of the composite probe stock solution is added to a centrifuge tube, followed by 200 μL of ammonia or interfering substances at concentrations ranging from 0 to 500 ppm. The solution is then diluted to 2 mL with water, and the color change is observed and recorded. The RGB values ​​in the color space are obtained from the experimental images. The visual response of the probe to ammonia is tracked through the overall color change and can be calculated as the Euclidean distance (ED). In the formula, R0 / G0 / B0 represents the color before the reaction, and R / G / B represents the color after the reaction.

[0019] The implementation principle of this invention: The HRCC composite probe described in this invention achieves selective enrichment and in-situ response to ammonia by constructing a three-dimensional hydrogen bond network. This mechanism not only significantly improves the sensitivity of ammonia detection but also endows cat litter with the function of actively adsorbing and purifying ammonia, realizing "detection + absorption" in a single material system. In practical applications, a momentary change in the pH value of the area in contact with pet urine triggers a color change in the HRCC composite probe, providing a visual indication of urine pH. As the storage time increases, excrement decomposes under the action of microorganisms, producing ammonia, which is continuously captured and enriched by the hydrogen bond network, causing the overall color of the cat litter to gradually change from yellow to blue as the ammonia concentration accumulates. Users can intuitively judge the hygiene status of the cat litter and when to replace it based on the color change.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1. The HRCC composite probe designed in this invention improves sensitivity and continuous response to ammonia gas by several times compared with traditional single colorimetric agents through hydrogen bond enrichment mechanism. It has a fast response speed and can be integrated into traditional cat litter as an indicator probe to upgrade the product.

[0021] 2. The color-changing cat litter of this invention achieves the dual functions of instant urine pH health indication, long-term ammonia detection and active purification using a single material, fundamentally breaking through the technical pain point of cat litter in odor management.

[0022] 3. This invention transforms the complex chemical detection process into an intuitive color signal (gradual change from yellow and green to blue). Users do not need any professional equipment or knowledge; they can quickly determine the cat's health status and the timing of litter cleaning simply by observing with the naked eye, greatly improving ease of use.

[0023] 4. The color-changing cat litter of this invention uses readily available, inexpensive, green and safe raw materials, and its overall cost is far lower than that of existing smart monitoring cat litter products. At the same time, the preparation process is simple and environmentally friendly, and it is easy to realize industrial production, which has extremely high market promotion value and broad application prospects. Attached Figure Description

[0024] Figure 1 Images showing the before and after color changes of dual-function color-changing cat litter prepared with different formulations.

[0025] Figure 2 These are comparative photographs showing the color changes of the HRCC composite probe and bromophenol blue described in this invention at different ammonia concentrations (0, 0.5, 1, 2.5, 5, 10, 25, 50, 100, 250, 500 ppm).

[0026] Figure 3 The linear curves of Euclidean distance versus concentration for (a) the HRCC composite probe and (b) the bromophenol blue colorimetric reagent described in this invention in response to ammonia gas.

[0027] Figure 4 The infrared spectrum represents the adsorption performance of the HRCC hydrogen-bonded composite system for ammonia as described in this invention.

[0028] Figure 5 The color-changing cat litter described in this invention affects pH changes.

[0029] Figure 6 To simulate the ammonia gas produced by the decomposition of excrement (urease decomposes urea), the color change photos of the color-changing cat litter described in this invention were recorded at intervals of 5 min (Figures 1-5), 15 min (Figures 5-9), and 30 min (Figures 9-12) within 3 hours. Detailed Implementation

[0030] To better understand the present invention, the following specific embodiments further illustrate the content of the present invention. These are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1: Preparation of HRCC composite probe and bifunctional color-changing cat litter The specific preparation steps of an HRCC composite probe are as follows: 0.1 mol of betaine hydrochloride and 0.1 mol of tetrabutylammonium chloride are weighed and mixed in a molar ratio of 1:1 to obtain mixture A; 0.32 mol of polyethylene glycol and 0.08 mol of polyethylene glycol diglycidyl ether are weighed and mixed in a molar ratio of 4:1, and stirred at room temperature for 25 min to obtain mixture B. Mixtures A and B are mixed in a molar ratio of 1:2 and placed in a round-bottom flask. The mixture is then heated with magnetic stirring in a 60℃ constant-temperature oil bath for 45 min until a homogeneous, transparent, and precipitate-free liquid is formed. Subsequently, 0.5 g of bromophenol blue is added to 10 g of the above system, and stirring is continued at the same temperature for 20 min to ensure complete dissolution and embedding of the cross-linked hydrogen bond network. After degassing for 10 min, the HRCC composite probe is obtained. The obtained HRCC composite probe is diluted with deionized water as needed and brought to a final volume of 100 mL to obtain a composite probe stock solution with a colorimetric reagent concentration of 5 mg / mL for later use.

[0032] The specific raw material composition of a dual-function color-changing cat litter is as follows: 90% tofu residue fiber powder, 2% guar gum, 8% corn starch, HRCC-1 composite probe, and appropriate amount of water. Specifically, 900 g of tofu residue fiber powder, 20 g of guar gum, and 80 g of corn starch are weighed and premixed at room temperature for 5 min. Then, about 50 g of deionized water is slowly added, and the mixture is continuously stirred at 1200 rpm until a uniform wet cat litter is formed. Subsequently, 100 mL of the HRCC composite probe mother liquor from Example 1 is evenly sprayed onto the tumbling wet material, and stirring is continued to ensure that the probe molecules are evenly distributed in the wet material. At this point, the wet material has an initial light yellow color. The wet material is extruded and granulated using a granulator. The resulting wet granules are dried in an 80℃ drying oven until the moisture content of the cat litter granules is less than 10%. Finally, the color-changing cat litter product with a particle size range of 2 mm is collected.

[0033] Following the above method, the only difference lies in changing the key parameters and formulations of the HRCC composite probe and the color-changing cat litter preparation, as shown in Table 1 below. Each formulation (Group 1 (HRCC-1), Group 2 (HRCC-2), Group 3 (HRCC-3)) imparts effective ammonia-induced color-changing function to the cat litter. Figure 1 Group 1, which also has a cost advantage, is the optimal solution overall.

[0034] Table 1 Example 2: Testing the detection and absorption performance of an HRCC composite probe for ammonia. (1) Detection performance test Taking the HRCC-1 probe in Example 1 as an example, 11 centrifuge tubes were used, and the composite probe stock solution and ammonia water of different concentrations were added to them respectively. At the instant the ammonia water was added (less than 1 second), the color of the probe solution changed immediately and quickly stabilized. Figure 2 As shown, as the ammonia concentration increases from 0 to 500 ppm, the solution color changes across the color gamut, from yellow and green to blue, which can be observed with the naked eye.

[0035] To quantitatively describe color changes, image analysis was used to extract the RGB values ​​of each solution's color, and its Euclidean distance relative to the blank sample was calculated. The results are as follows: Figure 3 The results show that, within the concentration range of 0–100 ppm, the Euclidean distance exhibits a good linear relationship with the logarithm of the ammonia concentration, and the fitted curve equation is ED = 138lgc + 36 (R 2 =0.9902), and the colorimetric detection limit (LOD) is 0.09 ppm.

[0036] As a comparison, 0.05 g of bromophenol blue chromogenic reagent was dissolved in 10 mL of anhydrous water to obtain a conventional chromogenic reagent solution with a concentration of 5 mg / mL (without the treatment described in this invention), and the same ammonia response test was performed. The results showed that the control solution only showed a visually perceptible green change when the ammonia concentration reached 10 ppm, while the HRCC-1 composite probe of this invention only showed a green change at 2.5 ppm, improving the sensitivity to ammonia response by approximately 7 times.

[0037] Furthermore, parallel experiments were conducted to test for five common interfering substances that may be present in cat urine, such as proteins, urea, and gases. Under the same conditions, only ammonia gas produced a significant yellow-to-green color change in the probe, while the presence of other interfering substances resulted in almost no change. In summary, this composite probe exhibits significant advantages such as fast response speed, high sensitivity, intuitive color change, and good selectivity.

[0038] (2) Absorption performance test 1 g of HRCC-1 composite probe sample was placed in a 2 L sealed gas collection bag and filled with ammonia gas at an initial concentration of 300 ppm. After 45 minutes, the concentration of the remaining ammonia gas in the gas collection bag was measured using an ammonia gas detection tube, which showed that it had dropped to 150 ppm, and the ammonia removal rate reached 50%, which is equivalent to an absorption of 0.6 g NH3 / 1 g HRCC-2.

[0039] Fourier transform infrared spectroscopy (FT-IR) analysis was performed on the hydrogen-bonded system before and after ammonia absorption, such as... Figure 4 As shown, the sample after absorption is at 1647 cm⁻¹. -1 A distinct new characteristic absorption peak appeared at the ammonia molecule, which is attributed to the bending vibration of the NH bond in the ammonia molecule. All of the above results confirm that the HRCC composite probe has an effective absorption capacity for ammonia.

[0040] Example 3: Effect Test of a Dual-Function Color-Changing Cat Litter (1) Health Tip (pH Response Color Change) Test The color-changing cat litter prepared in group 1 of Example 1 was spread evenly in a petri dish. 1 mL of freshly prepared aqueous solutions with different pH values ​​were added to the surface of the litter to simulate cat urination behavior, and the results were observed and recorded. After the liquid was added, the litter area in contact with the liquid immediately absorbed water and clumped together. The introduction of the color-changing probe did not negatively affect the original properties of the tofu cat litter. Figure 5The results showed that when acidic or neutral (6-7) solutions were added, the color of the contact area did not change significantly. When a weakly alkaline solution with pH 8 was added, the contact area changed from pale yellow to blue-green. When a strongly alkaline solution with pH 9 was added, the contact area quickly turned blue. This phenomenon indicates that the HRCC composite probe in the cat litter has a sensitive naked-eye visual response to urine pH, which can help to provide an immediate and intuitive indication of alkaline urine (common in urinary tract infections).

[0041] (2) Odor detection - absorption (ammonia response) test To verify the ability of color-changing cat litter to monitor the ammonia production process, the process of urea in excrement being decomposed by microorganisms to produce ammonia was simulated. 1 mL of 0.01% urea solution and 100 μL of 100 U / mL urease solution were added to the cat litter in sequence, and the color change was recorded over 3 hours at room temperature.

[0042] The results are as follows Figure 6 As shown, the cat litter is initially a uniform yellow color. As urease catalyzes the continuous hydrolysis of urea to produce ammonia, the color of the litter in some areas gradually changes from yellow to blue-green, and in most areas it turns into a striking blue, indicating that the accumulated concentration of ammonia has reached a high level. It is recommended to change the cat litter in time.

[0043] Furthermore, the product was tested on real, healthy cats. The cats showed no signs of rejection or discomfort and successfully entered the litter box to defecate. Observations revealed that the litter area in contact with urine and feces gradually changed color from an initial pale yellow to blue over time. After one day, the litter at the excretion site became a clearly visible blue, clearly indicating the area requiring cleaning. These results demonstrate that the color-changing litter has good practical applicability and a cleaning indicator function.

[0044] (3) Odor removal test In the odor removal test, 3 g of blank tofu cat litter and 3 g of the color-changing cat litter of this invention were placed in two 2 L sealed gas bags, respectively, and both were filled with ammonia gas at an initial concentration of 300 ppm. After 45 minutes, the remaining ammonia concentration was measured. The ammonia concentration in the blank cat litter group was 65 ppm (removal rate 78%), while the ammonia concentration in the color-changing cat litter group of this invention dropped to 40 ppm (removal rate 87%). Compared with ordinary cat litter, the color-changing cat litter of this invention reduces the free ammonia concentration by approximately 38%. This is because the HRCC composite probe has a certain ability to actively adsorb and eliminate ammonia, achieving the absorption and purification of some odors while providing a color warning.

[0045] In summary, the color-changing cat litter prepared by this invention successfully achieves the dual functions of providing immediate health alerts for urine pH and long-term hygiene monitoring of ammonia accumulation concentration. It also possesses active deodorization capabilities, with intuitive color changes, high sensitivity, and controllable cost, demonstrating promising application prospects.

Claims

1. A method for preparing an ammonia-responsive hydrogen-bonded composite probe, characterized in that, Includes the following steps: (1) Mix betaine hydrochloride and tetrabutylammonium chloride evenly to obtain a first mixture; mix polyethylene glycol and polyethylene glycol diglycidyl ether evenly to obtain a second mixture; (2) The first mixture and the second mixture are mixed to carry out a crosslinking reaction to obtain a crosslinked polymer matrix; (3) The cross-linked polymer matrix is ​​mixed with a color developer, so that the color developer is embedded in the cross-linked polymer matrix to obtain the ammonia-responsive hydrogen bond composite probe.

2. The method for preparing the ammonia-responsive hydrogen-bonded composite probe according to claim 1, characterized in that, In step (1), the betaine hydrochloride and tetrabutylammonium chloride are mixed in a molar ratio of 1:1 to 3:1; the polyethylene glycol and polyethylene glycol diglycidyl ether are mixed in a molar ratio of 2:1 to 5:

1.

3. The method for preparing the ammonia-responsive hydrogen-bonded composite probe according to claim 1, characterized in that, In step (2), the first mixture and the second mixture are mixed at a total molar ratio of 1:1 to 1:4; The cross-linking reaction is carried out at a temperature of 40~80℃ for 20~60 min.

4. The method for preparing the ammonia-responsive hydrogen-bonded composite probe according to claim 1, characterized in that, In step (3), the mass ratio of the crosslinked polymer matrix to the color developer is 10:0.05~5; The colorimetric reagent is bromophenol blue; The mixing temperature is the same as the crosslinking reaction temperature in step (2).

5. An ammonia-responsive hydrogen-bonded composite probe prepared by the preparation method according to any one of claims 1-4.

6. The application of the ammonia-responsive hydrogen bond composite probe according to claim 5 in the preparation of a dual-function color-changing cat litter for health alerts and odor detection and absorption.

7. The application according to claim 6, characterized in that, When used, the color of the cat litter changes from yellow to blue as the concentration of ammonia increases.

8. A dual-function color-changing cat litter for health alerts and odor detection / absorption, characterized in that, It comprises a cat litter substrate, an adhesive, a thickener, and the ammonia-responsive hydrogen bond composite probe as described in claim 5.

9. The dual-function color-changing cat litter with health alerts and odor detection-absorption as described in claim 8, characterized in that, The cat litter substrate is selected from at least one of tofu residue fiber powder, corn starch, and tapioca starch, accounting for 80% to 95% of the total mass of the cat litter; The binder and thickener are each selected from at least one of guar gum, corn starch, and maltodextrin, and the binder and thickener together account for 5% to 20% of the total mass of the cat litter. The ammonia-responsive hydrogen-bonded composite probe accounts for 0.005% to 0.5% of the total mass of cat litter.

10. The preparation method of the dual-function color-changing cat litter with health alert and odor detection-absorption as described in claim 8 or 9, characterized in that, Includes the following steps: (1) Mix the cat litter base material, adhesive and thickener and water to form a uniform wet cat litter; (2) The ammonia-responsive hydrogen bond composite probe solution is uniformly applied to the wet cat litter and mixed evenly; (3) The material obtained in step (2) is granulated, dried and screened to obtain the dual-function color-changing cat litter.

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