A method for preparing a titanium hydride / lignin two-dimensional nanosheet composite material and its ultraviolet shielding application.

Abstract

This invention relates to the field of ultraviolet shielding materials, specifically a method for preparing a TiH2 / lignin two-dimensional nanosheet composite material and its ultraviolet shielding application. First, a deionized aqueous dispersion of lignin is ball-milled and then freeze-dried under vacuum to obtain flake-like lignin. Then, TiH2 powder is ball-milled, dried, dissolved in an aqueous nitric acid solution, and acid-washed. After washing and drying, TiH2 powder is obtained, which is then dispersed and mixed with the flake-like lignin in an aqueous solution. The mixture is then sonicated, and the resulting suspension is separated into solids and freeze-dried to obtain the TiH2 / lignin nanosheet composite material. This invention uses ultrasonic treatment to composite lignin nanosheets and TiH2, avoiding the aggregation of lignin nanosheets. Simultaneously, TiH2 forms a uniform nanosheet structure, which is more conducive to the reaction of TiH2 with external free radicals to form TiO2, resulting in excellent overall ultraviolet shielding and antioxidant capabilities.

Description

Technical Field

[0001] This invention relates to the field of ultraviolet shielding materials technology, specifically to a method for preparing a TiH2 / lignin two-dimensional nanosheet composite material and its application. Background Technology

[0002] With the depletion of the ozone layer, more ultraviolet (UV) radiation from the sun reaches the Earth's surface. The high energy of UV radiation can lead to sunburn, premature skin aging, and even skin cancer. Inorganic nanoparticles, as UV protectants, are limited by their high mass density and photocatalytic activity, inherent cytotoxicity, and lack of biocompatibility. Therefore, combining inorganic components with natural organic ingredients in sunscreens has become an emerging research direction in the field of UV protection.

[0003] Titanium hydride (TiH2) is a grayish-black inorganic compound. In applications, the active hydrogen in titanium hydride exhibits a significant potential for scavenging hydroxyl radicals, allowing it to form titanium dioxide (TiO2) in situ. This titanium dioxide possesses anti-UV effects, exhibiting a strong ability to absorb ultraviolet light during the scavenging of ·OH radicals. Simultaneously, titanium hydride may reflect and scatter ultraviolet light by forming a physical barrier, reducing direct contact and damage to the skin. However, direct use of titanium hydride powder for UV shielding presents a problem of poor biocompatibility. Compared to raw titanium hydride powder, titanium hydride nanosheets have a higher specific surface area, enabling better absorption of free radicals and providing antioxidant properties and UV shielding.

[0004] Chinese patent CN108456314A mixes 2,4-dihydroxybenzophenone and dihaloalkanes, reacts them in an ice-water bath under acid-binding agent and solvent conditions, to obtain a reactive ultraviolet absorber. The reactive ultraviolet absorber is dissolved in an organic solvent and added dropwise to an alkaline solution of lignin to obtain a lignin-based polymeric ultraviolet protectant. This preparation process uses a large amount of toxic organic solvent. Chinese patent CN111228141A dissolves lignin and dopamine hydrochloride in a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution, adds ammonium persulfate and hydrogen peroxide, stirs for 8–36 hours, centrifuges, and dialyzes the supernatant to obtain a lignin-polydopamine composite material. This preparation process is time-consuming and complex. To date, there are no reports of combining the inorganic component TiH2 with the natural organic component lignin for use in ultraviolet-resistant materials. Summary of the Invention

[0005] To address the hazards of organic UV-shielding materials to humans and the environment, and the limitations of inorganic UV-resistant nanoparticles as UV protectants due to their high mass density and photocatalytic activity, as well as their inherent cytotoxicity and lack of biocompatibility, this invention proposes a method for preparing a TiH2 / lignin two-dimensional nanosheet composite material.

[0006] To achieve the objectives of this invention, the following technical solution is adopted:

[0007] A method for preparing a titanium hydride / lignin two-dimensional nanosheet composite material includes the following steps:

[0008] (1) Mix an appropriate amount of lignin with deionized water by stirring (mass ratio of 1:10-30), and then ball mill the mixture in a ball mill at 200-300 rpm for 1-3 hours to obtain a lignin nanosheet mixture. After centrifugation, the precipitate is freeze-dried to obtain lignin nanosheets.

[0009] (2) Mix an appropriate amount of titanium hydride with deionized water by stirring (mass ratio 1:10-20). Mill the mixture in a ball mill at 300-600 rpm for 1-3 hours to obtain a titanium hydride mixture. Centrifuge and dry the mixture. Prepare an acid pickling solution by mixing HNO3 and water to obtain a 0.5%-5% (w / w) nitric acid aqueous solution. Immerse an appropriate amount of titanium hydride powder in the prepared acid pickling solution for acid pickling (0.05 g / mL-0.25 g / mL) for 90-180 seconds. After acid pickling, thoroughly wash the titanium hydride powder with deionized water and centrifuge to remove residual acid from the surface. Dry the powder in an oven.

[0010] (3) Add the powder obtained in steps (1) and (2) to deionized water at a ratio of 1:(0.2-6) and mix evenly (0.1 g / mL-0.45 g / mL). Add the resulting suspension to an ultrasonic reactor and sonicate at a power of 200-300 W for 10-30 minutes. After centrifugation at 5000-10000 rpm for 3-10 minutes, wash with deionized water, centrifuge, and freeze-dry to obtain the titanium hydride / lignin two-dimensional nanosheet composite material.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0012] This invention obtains TiH by acid washing of TiH2. 1.92 This removes some of the oxide layer and contaminants, allowing TiH to... 1.92This invention exhibits superior antioxidant and UV-shielding properties. Lignin is ball-milled and ultrasonically treated to obtain a lignin sheet structure with a smaller particle size. The lignin nanosheets are then ultrasonically treated with titanium hydride. The groups on the titanium hydride surface form hydrogen bonds with the abundant functional groups on the lignin surface, preventing aggregation between lignin nanosheets and resulting in dispersed nanoscale lignin sheets with excellent UV absorption capabilities. Simultaneously, ultrasonic treatment further disperses the titanium hydride, allowing some lignin to intercalate into the titanium hydride structure. This forms a uniform nanosheet structure, which is more conducive to the reaction of titanium hydride with external free radicals to form TiO2, providing better UV shielding capabilities. The partial oxidation of Ti in the titanium hydride over time, absorbing free radicals and transforming into TiO2, continuously enhances the UV resistance of the composite material, exhibiting excellent antioxidant properties. The synergistic effect of lignin and titanium hydride significantly improves the UV shielding capability of the nanocomposite material. The titanium hydride / lignin nanosheet composite material prepared by the above method of this invention has a high specific surface area, avoids aggregation, and fully utilizes the material's inherent UV resistance and antioxidant properties. Attached Figure Description

[0013] Figure 1 The lignin and TiH prepared in Example 1 1.92 TiH 1.92 / Lignin sample and TiH prepared in Example 3 1.92 XRD patterns of lignin samples after 10 min and 30 min of sonication;

[0014] Figure 2 The lignin nanosheets and TiH prepared in Example 1 1.92 TiH 1.92 / Lignin lamellar structure, TiH prepared in Example 3 1.92 Solid-state UV absorption spectra of lignin lamellar structure and TiH2 lamellar structure and TiH2 / lignin lamellar structure samples prepared in Comparative Example 1;

[0015] Figure 3 The lignin nanosheets and TiH prepared in Example 1 1.92 TiH 1.92 / Lignin lamellar structure, TiH prepared in Example 3 1.92 Solid-state UV transmission spectra of lignin lamellar structure and TiH2 lamellar structure and TiH2 / lignin lamellar structure samples prepared in Comparative Example 1;

[0016] Figure 4 TiH prepared in Example 1 1.92 TiH 1.92 / TEM images of lignin lamellar structure in the 200 nm and 100 nm scale bar range;

[0017] Figure 5The lignin nanosheets and TiH prepared in Example 1 1.92 / DPPH removal rate of lignin lamellar structure.

[0018] Figure 6 SPF values ​​for each embodiment, comparative embodiment, lignin, and titanium hydride. Detailed Implementation

[0019] Example 1: (1) A suitable amount of lignin and deionized water were mixed evenly by stirring (mass ratio of 1:20) to obtain a mixture. The mixture was ball-milled in a ball mill at 200 rpm for 2 hours to obtain a lignin nanosheet mixture. The precipitate obtained after centrifugation was freeze-dried to obtain a lignin nanosheet structure.

[0020] (2) A suitable amount of TiH2 and deionized water were mixed evenly by stirring (mass ratio 1:10) to obtain a mixture. The mixture was then ball-milled at 400 rpm for 3 hours to obtain a TiH2 mixture. After centrifugation, the mixture was dried. HNO3 and water were mixed to prepare an acid washing solution, resulting in a 3% nitric acid aqueous solution. A suitable amount of titanium hydride powder was immersed in the prepared acid washing solution for acid washing (0.15 g / mL) for 100 seconds. The acid-washed TiH2... 1.92 The powder is thoroughly washed with deionized water and centrifuged to remove residual acid from the surface, and then dried in an oven.

[0021] (3) The powders obtained in steps (1) and (2) were added to deionized water at a mass ratio of 2:1 and mixed evenly (0.15 g / mL). The resulting suspension was added to an ultrasonic tank and ultrasonicated at 250 W for 20 minutes. After centrifugation at 10000 rpm for 6 minutes, the mixture was washed with deionized water, centrifuged again, and then freeze-dried to obtain TiH. 1.92 / Lignin two-dimensional nanosheet composite material.

[0022] The TiH prepared in this embodiment 1.92 X-ray powder diffraction experiments were conducted on lignin composite materials, and their morphology and structure were observed under a transmission electron microscope. Their ultraviolet shielding effect was also tested under a solid-state ultraviolet spectrometer.

[0023] XRD patterns as follows Figure 1 As shown: TiH 1.92 The material shows multiple diffraction peaks, which are TiH2 diffraction peaks; TiH 1.92 TiH 1.92 TEM images of lignin platy structures are shown below. Figure 4 As shown in Figures a) and b), TiH was prepared in Example 1. 1.92 Structure; c) and d) are TiH 1.92TEM images of the lignin-like lamellar structure after sonication for 30 min, within the 200 nm and 100 nm scale bars. The images show the prepared TiH... 1.92 The lignin and lignin are stacked in a sheet-like manner, providing a larger interface area, reducing aggregation, and improving UV shielding ability.

[0024] Lignin nanosheets, TiH 1.92 / DPPH removal rate of lignin platy structures, such as Figure 5 As shown, the test method for DPPH scavenging rate is as follows: Composite materials of different concentrations are added to a DPPH ethanol solution, and then vigorously stirred in the dark to determine their DPPH scavenging ability. After 5 minutes, the UV-Vis absorbance at 517 nm is measured every 30 minutes, and the average value is taken. The DPPH scavenging activity can be calculated using the following formula.

[0025]

[0026] Where A0 is the absorbance of the blank control, As is the absorbance of the test sample, and A1 is only the absorbance of the solution without the composite material. A higher DPPH scavenging rate indicates better antioxidant properties of the material, providing better UV shielding performance. Figure 5 It can be seen that adding TiH 1.92 Afterwards, TiH 1.92 The reaction with free radicals produces titanium oxide, which improves the DPPH removal rate of the composite material.

[0027] TiH 1.92 SPF numerical spectrum of lignin composite material as follows Figure 6 As shown, according to the Colita standard, 100 mg of powder and 900 mg of glycerin were mixed evenly in an agate mortar to prepare a simulated sunscreen agent with a mass ratio of 1:9. 32.5 mg of the sample was weighed onto a PMMA test plate (5×5 cm) using an analytical balance and spread evenly with a finger wearing a finger cot. The SPF of the sample was then tested using an SPF meter. A higher SPF indicates better UV protection; in this example, the value was 8.3.

[0028] Example 2: (1) A suitable amount of lignin and deionized water were mixed evenly by stirring (mass ratio of 1:10). The mixture was ball-milled in a ball mill at 300 rpm for 1 h to obtain a lignin nanosheet mixture. The precipitate obtained after centrifugation was freeze-dried to obtain a lignin nanosheet structure.

[0029] (2) A suitable amount of TiH2 and deionized water were mixed evenly by stirring (mass ratio 1:20). The mixture was then ball-milled at 300 rpm for 3 hours to obtain a TiH2 nanosheet mixture. After centrifugation, the mixture was dried. HNO3 and water were mixed to prepare an acid washing solution, resulting in a 5% nitric acid aqueous solution. A suitable amount of titanium hydride powder was immersed in the prepared acid washing solution for acid washing (0.25 g / mL) for 90 seconds. The acid-washed TiH2... 1.92 The powder is thoroughly washed with deionized water and centrifuged to remove residual acid from the surface, and then dried in an oven.

[0030] (3) The powders obtained in steps (1) and (2) were added to deionized water at a mass ratio of 1:1 and mixed evenly (0.1 g / mL). The resulting suspension was added to an ultrasonic tank and ultrasonicated at 300 W for 10 minutes. After centrifugation at 5000 rpm for 10 minutes, the mixture was washed with deionized water, centrifuged again, and then freeze-dried to obtain TiH. 1.92 / Lignin two-dimensional nanosheet composite material.

[0031] TiH 1.92 SPF numerical spectrum of lignin composite material as follows Figure 6 As shown, the value in this embodiment is 8.2.

[0032] Example 3: (1) A suitable amount of lignin and deionized water were mixed evenly by stirring (mass ratio of 1:30). The mixture was ball-milled in a ball mill at 250 rpm for 3 hours to obtain a lignin nanosheet mixture. The precipitate obtained after centrifugation was freeze-dried to obtain a lignin nanosheet structure.

[0033] (2) A suitable amount of TiH2 and deionized water were mixed evenly by stirring (mass ratio 1:10). The mixture was then ball-milled at 600 rpm for 2 hours to obtain a TiH2 nanosheet mixture. After centrifugation, the mixture was dried. HNO3 and water were mixed to prepare an acid washing solution, resulting in a 0.5% nitric acid aqueous solution. A suitable amount of titanium hydride powder was immersed in the prepared acid washing solution for acid washing (0.05 g / mL) for 180 seconds. The acid-washed TiH2... 1.92 The powder is thoroughly washed with deionized water and centrifuged to remove residual acid from the surface, and then dried in an oven.

[0034] (3) The powder obtained in steps (1) and (2) was added to deionized water at a ratio of 1:6 and mixed evenly (0.35 g / mL). The resulting suspension was added to an ultrasonic tank and ultrasonicated at 250 W for 30 minutes. After centrifugation at 8000 rpm for 8 minutes, the mixture was washed with deionized water, centrifuged again, and then freeze-dried to obtain TiH. 1.92 / Lignin two-dimensional nanosheet composite material.

[0035] TiH 1.92 SPF numerical spectrum of lignin composite material as follows Figure 6 As shown, the value in this embodiment is 7.9.

[0036] Example 4: (1) A suitable amount of lignin and deionized water were mixed evenly by stirring (mass ratio of 1:20). The mixture was ball-milled in a ball mill at 280 rpm for 2.5 h to obtain a lignin nanosheet mixture. The precipitate obtained after centrifugation was freeze-dried to obtain a lignin nanosheet structure.

[0037] (2) A suitable amount of TiH2 and deionized water were mixed evenly by stirring (mass ratio 1:20). The mixture was then ball-milled at 400 rpm for 1 h to obtain a TiH2 nanosheet mixture. After centrifugation, the mixture was dried. HNO3 and water were mixed to prepare an acid washing solution, resulting in a 3.5% nitric acid aqueous solution. A suitable amount of titanium hydride powder was immersed in the prepared acid washing solution for acid washing (0.12 g / mL) for 120 seconds. The acid-washed TiH2... 1.92 The powder is thoroughly washed with deionized water and centrifuged to remove residual acid from the surface, and then dried in an oven.

[0038] (3) The powders obtained in steps (1) and (2) were added to deionized water at a mass ratio of 5:1 and mixed evenly (0.3 g / mL). The resulting suspension was added to an ultrasonic tank and ultrasonicated at 225 W for 15 minutes. After centrifugation at 7500 rpm for 8 minutes, the mixture was washed with deionized water, centrifuged again, and then freeze-dried to obtain TiH. 1.92 / Lignin two-dimensional nanosheet composite material.

[0039] TiH 1.92 SPF numerical spectrum of lignin composite material as follows Figure 6 As shown, the value in this embodiment is 8.1.

[0040] Example 5: (1) A suitable amount of lignin and deionized water were mixed evenly by stirring (mass ratio of 1:30). The mixture was ball-milled in a ball mill at 200 rpm for 2.5 h to obtain a lignin nanosheet mixture. The precipitate obtained after centrifugation was freeze-dried to obtain a lignin nanosheet structure.

[0041] (2) A suitable amount of TiH2 and deionized water were mixed evenly by stirring (mass ratio 1:10). The mixture was then ball-milled at 600 rpm for 2 hours to obtain a TiH2 nanosheet mixture. After centrifugation, the mixture was dried. HNO3 and water were mixed to prepare an acid washing solution, resulting in a 2.8% nitric acid aqueous solution. A suitable amount of titanium hydride powder was immersed in the prepared acid washing solution for acid washing (0.2 g / mL) for 90 seconds. The acid-washed TiH2... 1.92The powder is thoroughly washed with deionized water and centrifuged to remove residual acid from the surface, and then dried in an oven.

[0042] (3) The powders obtained in steps (1) and (2) were added to deionized water at a ratio of 5:4 and mixed evenly (0.45 g / mL). The resulting suspension was added to an ultrasonic tank and ultrasonicated at 250 W for 25 minutes. After centrifugation at 9000 rpm for 3 minutes, the mixture was washed with deionized water, centrifuged again, and then freeze-dried to obtain TiH. 1.92 / Lignin two-dimensional nanosheet composite material.

[0043] TiH 1.92 SPF numerical spectrum of lignin composite material as follows Figure 6 As shown, the value in this embodiment is 8.0. Comparative Example 1: (1) A suitable amount of lignin and deionized water were mixed evenly by stirring (mass ratio of 1:20), and the mixture was ball-milled in a ball mill at 200 rpm for 2 hours to obtain a lignin nanosheet mixture. The precipitate obtained after centrifugation was freeze-dried to obtain a lignin nanosheet structure.

[0044] (2) Mix an appropriate amount of TiH2 with deionized water by stirring (mass ratio 1:10), and ball mill the mixture in a ball mill at 400 rpm for 3 h to obtain a TiH2 nanosheet mixture. After centrifugation, dry the mixture.

[0045] (3) The powder obtained in steps (1) and (2) was added to deionized water at a ratio of 2:1 and mixed evenly (0.15 g / mL). The resulting suspension was added to an ultrasonic reactor and ultrasonically treated for 20 minutes at a power of 250 W. After centrifugation at 10000 rpm for 6 minutes, the mixture was washed with deionized water, centrifuged again, and then freeze-dried to obtain the TiH2 / lignin two-dimensional nanosheet composite material.

[0046] Depend on Figure 2 It can be seen that the ultraviolet absorption rate of the composite material composed of un-acid-washed TiH2 is lower than that of other samples, because excessive hydrogen blocks the ultraviolet shielding property of titanium hydride in the composite material. Figure 6 The SPF is 2.9.

[0047] Figure 2 The lignin nanosheets and TiH prepared in Example 1 1.92 TiH 1.92 / Lignin lamellar structure, TiH prepared in Example 3 1.92 Solid-state UV absorption spectra of lignin lamellar structure and TiH2 lamellar structure and TiH2 / lignin lamellar structure samples prepared in Comparative Example 1; Figure 3 The lignin nanosheets and TiH prepared in Example 1 1.92 TiH 1.92 / Lignin lamellar structure, TiH prepared in Example 3 1.92 Solid-state UV transmission spectra of lignin lamellar structures and TiH2 lamellar structures prepared in Comparative Example 1, and TiH2 / lignin lamellar structure samples.

[0048] Depend on Figure 2 It can be seen that TiH 1.92 Compared to TiH2, it has a lower absorption rate in the non-UV region, which meets the characteristics of high UV absorption and low visible light absorption of UV shielding materials. Furthermore, TiH... 1.92 Ultraviolet absorption is higher in the ultraviolet region. As can be seen from the ultraviolet absorption spectra of Example 1 and Comparative Example 1, Example 1 exhibits good ultraviolet absorption in the ultraviolet region and low absorption in the visible light region. Figure 3 It can be seen that TiH 1.92 Compared to TiH2, it has lower ultraviolet transmittance. As can be seen from the ultraviolet transmission spectra of Example 1 and Comparative Example 1, the composite material of Example 1 has lower transmittance in the ultraviolet region and higher transmittance in the visible light region. Figure 2 , Figure 3 It can be seen that TiH 1.92 Composite materials have better UV shielding performance.

[0049] Comparative Example 2: (1) A suitable amount of lignin and deionized water were mixed evenly by stirring (mass ratio of 1:10). The mixture was ball-milled in a ball mill at 300 rpm for 1 h to obtain a lignin nanosheet mixture. The precipitate obtained after centrifugation was freeze-dried to obtain a lignin nanosheet structure.

[0050] (2) A suitable amount of TiH2 and deionized water were mixed evenly by stirring (mass ratio 1:20). The mixture was then ball-milled at 300 rpm for 3 hours to obtain a TiH2 nanosheet mixture. After centrifugation, the mixture was dried. HNO3 and water were mixed to prepare an acid washing solution, resulting in a 5% nitric acid aqueous solution. A suitable amount of titanium hydride powder was immersed in the prepared acid washing solution for acid washing (0.25 g / mL) for 90 seconds. The acid-washed TiH2... 1.92 The powder is thoroughly washed with deionized water and centrifuged to remove residual acid from the surface, and then dried in an oven.

[0051] (3) The powder obtained in steps (1) and (2) was added to deionized water at a ratio of 1:10 and mixed evenly (0.55 g / mL). The resulting suspension was added to an ultrasonic tank and ultrasonicated at 300 W for 30 minutes. After centrifugation at 5000 rpm for 10 minutes, the mixture was washed with deionized water, centrifuged again, and then freeze-dried to obtain TiH. 1.92 / Lignin two-dimensional nanosheet composite material.

[0052] In this comparative example, the ratio of lignin to titanium hydride in the composite material is not synergistic. The higher titanium hydride content requires high-power, long-duration ultrasonic treatment; however, under these conditions, the lignin structure is destroyed, resulting in poor interfacial bonding and inadequate UV shielding of the composite material. Figure 6 It can be seen that the SPF is 3.0. Comparative Example 3: (1) A suitable amount of lignin and deionized water were mixed evenly by stirring (mass ratio of 1:30), and the mixture was ball-milled in a ball mill at 250 rpm for 3 hours to obtain a lignin nanosheet mixture. The precipitate obtained after centrifugation was freeze-dried to obtain a lignin nanosheet structure.

[0053] (2) A suitable amount of TiH2 and deionized water were mixed evenly by stirring (mass ratio 1:10). The mixture was then ball-milled at 600 rpm for 2 hours to obtain a TiH2 nanosheet mixture. After centrifugation, the mixture was dried. HNO3 and water were mixed to prepare an acid washing solution, resulting in a 0.05% nitric acid aqueous solution. A suitable amount of titanium hydride powder was immersed in the prepared acid washing solution for acid washing (0.05 g / mL) for 180 seconds. The acid-washed TiH2... 1.92 The powder is thoroughly washed with deionized water and centrifuged to remove residual acid from the surface, and then dried in an oven.

[0054] (3) The powder obtained in steps (1) and (2) was added to deionized water at a ratio of 1:6 and mixed evenly (0.35 g / mL). The resulting suspension was added to an ultrasonic tank and ultrasonicated at 250 W for 30 minutes. After centrifugation at 8000 rpm for 8 minutes, the mixture was washed with deionized water, centrifuged again, and then freeze-dried to obtain TiH. 1.92 / Lignin two-dimensional nanosheet composite material.

[0055] In this comparative example, the titanium hydride was acid-washed with a 0.05% nitric acid aqueous solution. The acid concentration was too low, resulting in the titanium hydride oxide layer and some hydrogen not being washed away, thus leading to poor ultraviolet shielding performance. Figure 6 The SPF is 3.2.

[0056] Comparative Example 4: (1) A suitable amount of lignin and deionized water were mixed evenly by stirring (mass ratio of 1:20). The mixture was ball-milled in a ball mill at 280 rpm for 2.5 h to obtain a lignin nanosheet mixture. The precipitate obtained after centrifugation was freeze-dried to obtain a lignin nanosheet structure.

[0057] (2) A suitable amount of TiH2 and deionized water were mixed evenly by stirring (mass ratio 1:20). The mixture was then ball-milled at 400 rpm for 1 h to obtain a TiH2 nanosheet mixture. After centrifugation, the mixture was dried. HNO3 and water were mixed to prepare an acid washing solution, resulting in a 10% nitric acid aqueous solution. A suitable amount of titanium hydride powder was immersed in the prepared acid washing solution for acid washing (0.12 g / mL) for 120 seconds. The acid-washed TiH2... 1.92 The powder is thoroughly washed with deionized water and centrifuged to remove residual acid from the surface, and then dried in an oven.

[0058] (3) The powders obtained in steps (1) and (2) were added to deionized water at a ratio of 5:1 and mixed evenly (0.3 g / mL). The resulting suspension was added to an ultrasonic tank and ultrasonicated at 225 W for 15 minutes. After centrifugation at 7500 rpm for 8 minutes, the mixture was washed with deionized water, centrifuged again, and then freeze-dried to obtain TiH. 1.92 / Lignin two-dimensional nanosheet composite material.

[0059] In this comparative example, the titanium hydride was pickled with a high-concentration nitric acid solution, resulting in partial corrosion of the titanium and excessive hydrogen absorption, which deteriorated the ultraviolet shielding effect of the composite material. Figure 6 The SPF is 3.0.

[0060] Comparative Example 5: (1) A suitable amount of lignin and deionized water were mixed evenly by stirring (mass ratio of 1:30). The mixture was ball-milled in a ball mill at 200 rpm for 2.5 h to obtain a lignin nanosheet mixture. The precipitate obtained after centrifugation was freeze-dried to obtain a lignin nanosheet structure.

[0061] (2) A suitable amount of TiH2 and deionized water were mixed evenly by stirring (mass ratio 1:10). The mixture was then ball-milled at 600 rpm for 2 hours to obtain a TiH2 nanosheet mixture. After centrifugation, the mixture was dried. HNO3 and water were mixed to prepare an acid washing solution, resulting in a 2.8% nitric acid aqueous solution. A suitable amount of titanium hydride powder was immersed in the prepared acid washing solution for acid washing (0.2 g / mL) for 90 seconds. The acid-washed TiH2... 1.92 The powder is thoroughly washed with deionized water and centrifuged to remove residual acid from the surface, and then dried in an oven.

[0062] (3) Add the powder obtained in steps (1) and (2) to deionized water at a ratio of 10:1 and mix thoroughly (0.55 g / mL). Add the resulting suspension to an ultrasonic tank and sonicate at 250 W for 25 minutes. After centrifugation at 9000 rpm for 3 minutes, wash with deionized water, centrifuge again, and freeze-dry to obtain TiH. 1.92 / Lignin two-dimensional nanosheet composite material.

[0063] In this comparative example, the ratio of lignin to titanium hydride in the composite material is not synergistic. Excess lignin completely covers the titanium hydride nanosheets during ultrasonication, reducing the amount of titanium hydride absorbing free radicals and transforming into titanium oxide, thus resulting in poor ultraviolet shielding. Figure 6 The SPF is 3.1.

Claims

1. A method for preparing a TiH2 / lignin two-dimensional nanosheet composite material, characterized in that: The preparation steps are as follows: (1) Mix lignin with deionized water until homogeneous, and then ball mill the mixture in a ball mill to obtain a lignin nanosheet mixture. After centrifugation, the precipitate is freeze-dried to obtain lignin nanosheets. (2) Mix titanium hydride with deionized water until homogeneous. Then, ball mill the mixture in a ball mill to obtain a titanium hydride mixture. After centrifugation, dry the mixture. Immerse the obtained titanium hydride powder in an acid pickling solution for acid pickling. After acid pickling, wash the titanium hydride powder with water, centrifuge, and dry it to obtain acid-treated titanium hydride. The acid pickling solution is a nitric acid aqueous solution with a mass fraction of 0.5% to 5%. The acid pickling conditions are: immerse the titanium hydride powder in the acid pickling solution at a concentration of 0.05 g / mL to 0.25 g / mL for acid pickling, and the acid pickling time is 90 to 180 seconds. (3) The lignin nanosheets from step (1) and the acid-treated titanium hydride from step (2) are added to deionized water and mixed evenly. The resulting suspension is added to an ultrasonic vessel for ultrasonic treatment. After centrifugation, the mixture is washed and freeze-dried to obtain a titanium hydride / lignin two-dimensional nanosheet composite material. The mass ratio of the lignin nanosheets from step (1) to the acid-treated titanium hydride from step (2) is 1:(0.2~6).

2. The method for preparing the TiH2 / lignin two-dimensional nanosheet composite material according to claim 1, characterized in that: Step (2) ball milling involves milling the mixture in a ball mill at a speed of 300-600 rpm for 1-3 hours.

3. The method for preparing the TiH2 / lignin two-dimensional nanosheet composite material according to claim 1, characterized in that: In step (3), the ultrasonic power is 200~300 W and the ultrasonic treatment time is 10~30 minutes.

4. The TiH2 / lignin two-dimensional nanosheet composite material prepared by the method according to any one of claims 1-3.

5. The application of the TiH2 / lignin two-dimensional nanosheet composite material prepared by the method according to any one of claims 1-3 in ultraviolet shielding products.

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