Slow-release hydrogen production material containing nanosilicon and its application in aquatic ecosystem restoration

Abstract

The present application relates to a kind of gel microspheres containing nanometer silicon, the gel microspheres include 1-10wt% sodium alginate, 0.01-20wt% nanometer silicon, 1-10wt% crosslinking agent.The gel microspheres of the present application can effectively slow down the hydrogen production rate of nanometer silicon while not too much loss of total hydrogen production, extend the hydrogen production time.In addition, the gel microspheres can effectively prevent nanometer silicon from diffusing in water body, prevent nanometer silicon from directly contacting biology and producing toxic effect, and safely repair aquatic ecosystem.

Description

Technical Field

[0001] This invention relates to the field of environmental protection, and more particularly to a type of nano-silicon gel microsphere and its application in the restoration of aquatic ecosystems. Background Technology

[0002] In recent years, biomarkers at the cellular or molecular level have been proven to be important early warning indicators reflecting pollutant exposure and toxic effects. Reactive oxygen species (ROS) and antioxidant defense systems within organisms can serve as sensitive molecular ecotoxicological biomarkers, indicating early warning of environmental pollution. Therefore, restoring the oxidative stress state of aquatic organisms and improving their environmental capacity and self-purification ability can effectively prevent the toxic effects of pollutants on cells and tissues, thereby preventing and controlling the ecological risks caused by various environmental pollutants and avoiding the need for remediation after the collapse of the aquatic ecosystem.

[0003] Recent studies have shown that supplementing with exogenous antioxidants is an effective way to address oxidative stress and damage caused by increased reactive oxygen species in organisms under pollutant stress. Hydrogen molecules, due to their selective antioxidant properties, strong diffusivity, and biocompatibility, are considered a unique and ideal biological antioxidant. To date, hydrogen molecules have been shown to have therapeutic effects on various human diseases and animal models related to oxidative stress, and can effectively regulate plant growth and development and improve plant tolerance to external stresses, thus finding wide application in medicine, botany, and agronomy.

[0004] Nano-silicon, with its advantages of wide availability, low cost, high hydrogen storage density, convenient transportation, and continuous hydrogen release, is considered a promising hydrogen production material. The hydrogen release rate, total hydrogen production, and impact on the aquatic environment of nano-silicon are key to the restoration of aquatic ecosystems. The hydrogen release rate of nano-silicon is extremely rapid in the initial stages of the reaction, gradually ceasing production after equilibrium is reached. However, direct introduction of nano-silicon into water can cause turbidity, and direct contact with aquatic organisms may produce toxic effects. Therefore, research is needed to develop safer and more efficient hydrogen-releasing materials containing nano-silicon. Summary of the Invention

[0005] The purpose of this invention is to provide a gel microsphere containing nano-silicon, wherein the gel microsphere comprises 1-10 wt% sodium alginate, 0.01-20 wt% nano-silicon, and 1-10 wt% crosslinking agent.

[0006] In a preferred embodiment of the present invention, the nano-silicon is uniformly dispersed within the sodium alginate.

[0007] In a preferred embodiment of the present invention, the gel microspheres have a layered structure inside.

[0008] In a preferred embodiment of the present invention, the sodium alginate content in the gel microspheres is 1-10 wt%, preferably 1-6 wt%.

[0009] In a preferred embodiment of the present invention, the content of nano-silicon in the gel microspheres is 0.05-15 wt%, preferably 0.09-10 wt%.

[0010] In a preferred embodiment of the present invention, the content of the crosslinking agent in the gel microspheres is 1-10 wt%, preferably 1-6 wt%.

[0011] In a preferred embodiment of the present invention, the crosslinking agent is a metal crosslinking agent, preferably any one or a combination of calcium chloride, barium chloride, and zinc chloride.

[0012] In a preferred embodiment of the present invention, the particle size of the nano-silicon is 20nm-200nm, preferably 50nm-100nm.

[0013] In a preferred embodiment of the present invention, the particle size of the gel microspheres is 1-10 mm, preferably 3-5 mm.

[0014] In a preferred embodiment of the present invention, the continuous hydrogen production time of the gel microspheres containing 0.1g of nano-silicon exceeds 80h, preferably exceeds 100h.

[0015] In a preferred embodiment of the present invention, the gel microspheres can adsorb heavy metals, preferably Cu, with an adsorption rate greater than 80%, more preferably greater than 85%.

[0016] Another object of the present invention is to provide a method for preparing nano-silicon-containing gel microspheres, wherein the gel microspheres comprise 1-10 wt% sodium alginate, 0.01-20 wt% nano-silicon, and 1-10 wt% crosslinking agent, and the preparation method includes the following steps:

[0017] (1) After sterilizing a sodium alginate solution with a mass concentration of 2-5% (w / w) and cooling it to room temperature, add nano-silicon at a mass concentration of 0.3-0.5% wt of sodium alginate solution and stir at room temperature for 30-60 min at 500-600 r / min to obtain nano-silicon sodium alginate solution.

[0018] (2) The nano-sized sodium alginate solution prepared in step (1) is added dropwise at a rate of 1 drop / second to a CaCl2 solution with a mass percentage of 2-5% at a volume ratio of 1-5:1, and allowed to stand for 5-10 minutes to obtain the solution.

[0019] In a preferred embodiment of the present invention, the sodium alginate solution is prepared by adding sodium alginate to water and stirring at room temperature for no less than 6 hours with a magnetic stirring speed of 500-700 r / min until a viscous, transparent solution without white or pale yellow powder is obtained.

[0020] In a preferred embodiment of the present invention, the sterilization temperature is 110°C and the sterilization time is 20 minutes.

[0021] In the preferred embodiment of the present invention, step (1) involves stirring until the mixture is evenly dispersed with no powder floating, and the solution is a brown, opaque gel.

[0022] In a preferred embodiment of the present invention, the CaCl2 solution is prepared by adding calcium chloride to water and ultrasonically dispersing it until the calcium chloride is completely dissolved.

[0023] Another objective of this invention is to provide an application of nano-silicon-containing gel microspheres in the restoration of aquatic ecosystems.

[0024] In a preferred embodiment of the present invention, the aquatic ecosystem restoration includes any one or a combination of mitigating the toxicity of heavy metal pollution, increasing the hydrogen content in the aquatic ecosystem, increasing the survival rate of zebrafish, and promoting the growth of aquatic plants.

[0025] In a preferred embodiment of the present invention, the dosage of the gel microspheres is 0.1-10 g / L (based on nano-silicon), preferably 0.1-10 g / L (based on nano-silicon).

[0026] Unless otherwise stated, when this invention relates to percentages between liquids, the percentage is volume / volume percentage; when this invention relates to percentages between liquids and solids, the percentage is volume / weight percentage; when this invention relates to percentages between solids and liquids, the percentage is weight / volume percentage; the remainder is weight / weight percentage.

[0027] The technical effects of this invention are as follows:

[0028] 1. This invention prepares nano-silicon gel microspheres by encapsulating nano-silicon in sodium alginate gel microspheres. The layered structure of the gel microsphere material enables the nano-silicon material to be uniformly distributed and stably generate hydrogen inside the sphere. At the same time, the hydrogen gas generated by the nano-silicon material expands the gaps between the layered structures inside the gel microsphere, thereby giving the gel microsphere material excellent adsorption performance. It can effectively slow down the hydrogen production rate of nano-silicon and prolong the hydrogen production time without excessively losing the total amount of hydrogen produced.

[0029] 2. The gel microspheres of the present invention can effectively prevent the diffusion of nano-silicon in water, prevent nano-silicon from directly contacting organisms and producing toxic effects, improve the growth rate of aquatic plants and the survival rate of aquatic animals, and the gel microspheres can reduce the accumulation of heavy metal ions in organisms by adsorbing heavy metal ions in water, reduce the toxicity of heavy metal ions to organisms, and safely restore aquatic ecosystems.

[0030] 3. The preparation process of this invention is simple, the production cost is low, and the reaction product, silicon dioxide, is stable and non-toxic, making it suitable for industrial production. Attached Figure Description

[0031] Figure 1 Scanning electron microscope images of Example 1: (a) sodium alginate gel microspheres prepared in Comparative Example 1; (b)(c) sodium alginate gel microspheres prepared in Example 1; (d) nano-silicon material.

[0032] Figure 2 The cumulative hydrogen production of each group in Experiment Example 2: (a) pH 8.6; (b) pH 7;

[0033] Figure 3 The adsorption of copper by the gel microspheres in Experimental Example 3: (a) Comparative Example 1; (b) Example 1;

[0034] Figure 4 The average growth of Vallisneria natans in Experiment 4, (a) after 6 days of cultivation, (b) after 14 days of cultivation;

[0035] Figure 5 Comparison of mortality rates in zebrafish in Experiment Example 4;

[0036] Figure 6 Cu accumulation in zebrafish after 14 days of culture in Experiment Example 4. Detailed Implementation

[0037] The specific embodiments of the present invention will be further described below with reference to examples.

[0038] In this embodiment, elemental silicon nanoparticles were prepared by ball milling: 5 μm elemental silicon was used as raw material, and the mass ratio of elemental silicon to zirconium beads was 1:1. A two-step ball milling method was adopted: 0.5 mm zirconium beads were ball milled for 4 hours; 0.3 mm zirconium beads were ball milled for 4 hours; silicon oxide in the powder was cleaned with 5% HF; and the nano-silicon powder was soaked in ethanol to make its surface hydrophilic. The resulting nano-silicon particles had a particle size of 50 nm.

[0039] Example 1: Preparation of the present invention: Silicon-containing gel microspheres

[0040] The composition of the nano-silicon-containing gel microspheres of the present invention is as follows: 0.1g nano-silicon, 2g sodium alginate, 2g calcium chloride, and 100g water.

[0041] The preparation method of the nano-silicon-containing gel microspheres of the present invention includes the following steps:

[0042] (1) Disperse 2g of sodium alginate in 100g of ultrapure water, stir with magnetic stirring at 500r / min for 6h at room temperature; sterilize with a high temperature and high pressure sterilizer at 110℃ for 20 minutes.

[0043] (2) After the sodium alginate solution cools to room temperature, add 0.1g of nano-silicon and stir. The magnetic stirring speed is 500r / min, and the stirring is carried out at room temperature for 30min.

[0044] (3) Prepare a 2% wt CaCl2 solution as a crosslinking agent. Use a 2-20 mL syringe to uniformly drop 100 mL of sodium alginate solution containing nano-silicon into 100 mL of CaCl2 solution at a rate of one drop per second. Let it stand for 5 min to obtain gel microspheres with a particle size of 3 mm.

[0045] Example 2: Preparation of hydrogen-releasing gel microspheres containing nano-silicon

[0046] The composition of the nano-silicon-containing gel microspheres of this invention is as follows: 0.5g nano-silicon, 5g sodium alginate, 4g calcium chloride, and 150g water.

[0047] The preparation method of the nano-silicon-containing gel microspheres of the present invention includes the following steps:

[0048] (1) Disperse 5g of sodium alginate in 150g of ultrapure water, stir with magnetic stirring at 500r / min for 8h at room temperature; sterilize with a high temperature and high pressure sterilizer at 110℃ for 20 minutes.

[0049] (2) After the sodium alginate solution cools to room temperature, add 0.5g of nano-silicon and stir. The magnetic stirring speed is 600r / min, and the stirring is carried out at room temperature for 40min.

[0050] (3) Prepare a 2% wt CaCl2 solution as a crosslinking agent. Use a 10mL syringe to drop 150mL of sodium alginate solution containing nano-silicon into 200mL of CaCl2 solution at a rate of one drop per second. Let stand for 5min to obtain gel microspheres with a particle size of 3mm.

[0051] Example 3: Preparation of hydrogen-releasing gel microspheres containing nano-silicon

[0052] The composition of the nano-silicon-containing gel microspheres of this invention is as follows: 0.3g nano-silicon, 6g sodium alginate, 8g calcium chloride, and 100g water.

[0053] The preparation method of the nano-silicon-containing gel microspheres of the present invention includes the following steps:

[0054] (1) Disperse 6g of sodium alginate in 100g of ultrapure water, stir magnetically at 700r / min for 10h at room temperature; sterilize in a high-temperature and high-pressure autoclave at 110℃ for 20 minutes.

[0055] (2) After the sodium alginate solution cools to room temperature, add 0.3g of nano-silicon and stir. The magnetic stirring speed is 600r / min, and the stirring is carried out at room temperature for 60min.

[0056] (3) Prepare a 4% wt CaCl2 solution as a crosslinking agent. Use a 10mL syringe to drop 100mL of sodium alginate solution containing nano-silicon into 200mL of CaCl2 solution at a rate of one drop per second. Let stand for 5min to obtain gel microspheres with a particle size of 3mm.

[0057] Example 4: Preparation of hydrogen-releasing gel microspheres containing nano-silicon

[0058] The composition of the nano-silicon-containing gel microspheres of this invention is as follows: 0.9g nano-silicon, 6g sodium alginate, 8g calcium chloride, and 100g water.

[0059] The preparation method of the nano-silicon-containing gel microspheres of the present invention includes the following steps:

[0060] (1) Disperse 6g of sodium alginate in 100g of ultrapure water, stir magnetically at 700r / min for 10h at room temperature; sterilize in a high-temperature and high-pressure autoclave at 110℃ for 20 minutes.

[0061] (2) After the sodium alginate solution cools to room temperature, add 0.9g of nano-silicon and stir. The magnetic stirring speed is 600r / min, and the stirring is carried out at room temperature for 60min.

[0062] (3) Prepare a 4% wt CaCl2 solution as a crosslinking agent. Use a 10mL syringe to drop 100mL of sodium alginate solution containing nano-silicon into 200mL of CaCl2 solution at a rate of one drop per second. Let stand for 5min to obtain gel microspheres with a particle size of 3mm.

[0063] Comparative Example 1

[0064] Composition of gel microspheres: 2g sodium alginate, 2g calcium chloride, 100g water.

[0065] The preparation method of gel microspheres includes the following steps:

[0066] (1) Disperse 2g of sodium alginate in 100g of ultrapure water, stir with magnetic stirring at 500r / min for 6h at room temperature; sterilize with a high temperature and high pressure sterilizer at 110℃ for 20 minutes.

[0067] (2) Prepare a 2% wt CaCl2 solution as a crosslinking agent. Use a 2-20 mL syringe to uniformly drop 100 mL of sodium alginate solution containing nano-silicon into 100 mL of CaCl2 solution at a rate of one drop per second. Let stand for 5 min to obtain gel microspheres.

[0068] Experimental Example 1: SEM Observation Results

[0069] The structures of the gel microspheres prepared in Comparative Example 1, the silicon-containing gel microspheres prepared in Example 1, and the standalone silicon-containing material were observed using a scanning electron microscope, respectively. Figure 1 The gel microspheres prepared in Comparative Example 1 exhibit an overall layered structure. The layered structure of the silicon-containing gel microspheres prepared in Example 1 shows uniform distribution of silicon nanoparticles, with larger gaps between the layers and a larger overall specific surface area, thus enhancing the adsorption performance of the gel microspheres.

[0070] Experimental Example 2: Study on the hydrogen production performance of the gel microspheres of the present invention

[0071] An anaerobic flask with a volume of 100 mL was selected as the reaction vessel.

[0072] Experimental group 1: 80 mL of sodium borate buffer solution with pH = 8.6 was added to the anaerobic bottle, and 2 g of the nano-silicon-containing gel microspheres prepared in Example 1 were added;

[0073] Control group 1: 80 mL of sodium borate buffer solution with pH = 8.6 was added to the anaerobic bottle, along with 0.1 g of nano-silicon;

[0074] Experimental group 2: Add 80 mL of ultrapure water with pH = 7 to the anaerobic bottle, and add 2 g of the nano-silicon-containing gel microspheres prepared in Example 1;

[0075] Control group 2: 80 mL of ultrapure water with pH = 7 was added to the anaerobic bottle, along with 0.1 g of nano-silicon.

[0076] The anaerobic flasks were sealed, and the hydrogen production of the two groups was measured at the same time points. The total hydrogen production and the hydrogen production rate were statistically compared. Results are shown below. Figure 2 (a)(b). Compared with control groups 1 and 2, experimental groups 1 and 2 were able to achieve sustained hydrogen production for more than 84 hours.

[0077] Experimental Example 3: Study on the Adsorption Performance of the Gel Microspheres of the Present Invention

[0078] Adsorption kinetics studies were conducted in beakers at room temperature. Gel microspheres prepared in Example 1 and Comparative Example 1 were added to a 200 ppb standard copper solution at a dosage of 34.2 g / L. 3 ml water samples were collected at time points of 15 min, 30 min, 45 min, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 5 h, 6 h, and 12 h to determine the residual copper concentration in the water. Copper concentration was determined using the external standard method via ICP-MS. Standard solutions with copper concentrations of 5, 10, 20, 50, and 100 ppb were prepared and plotted. The test samples were diluted 5 times with 2% dilute nitric acid, and the copper ion content in the water was determined. Adsorption results are shown below. Figure 3 As shown, the adsorption ratio of copper by the gel microspheres in Comparative Example 1 was 48.85%, while the adsorption ratio of copper by the gel microspheres in Example 1 was as high as 88.47%.

[0079] Experimental Example 4: Study on the Restoration Effect of the Gel Microspheres of the Present Invention on Aquatic Ecosystems

[0080] An underwater ecosystem was simulated in a water tank. The experiment was divided into four treatment groups, namely...

[0081] Control group: No Cu ions or gel microspheres added;

[0082] Cu 2+ Exposure group (Cu): Cu ions were added to make the copper ion concentration in the ecosystem 200 ppb, without adding gel microspheres;

[0083] Cu 2+ + Hydrogen-producing material group (Cu+Si): Cu ions were added to make the copper ion concentration in the ecosystem 200 ppb, and then the gel microspheres of Example 1 were added at a dosage of 0.1 g / L (calculated as nano-silicon);

[0084] Hydrogen-producing material group (Si, without Cu): without adding Cu ions, add gel microspheres at a dosage of 0.1 g / L (based on nano-silicon).

[0085] The ecosystem cultivation cycle was 14 days. A 5cm layer of nutrient soil was placed at the bottom of each tank, with a water level of 25cm. Twelve *Vallisneria natans* plants were planted in each tank, arranged in two rows of three, for a total of six planting points, with two plants in each point. Healthy zebrafish were selected, with 25 fish introduced into each tank. The cultivation temperature was controlled at (25±2)℃, and the light cycle was light:dark (16h:8h). Aeration was performed using a fish pump for 12 hours daily to ensure dissolved oxygen levels were maintained at a minimum of approximately 5mg / L, as oxygen deficiency negatively impacts the growth of organisms within the system. Artemia shrimp were fed regularly at 0.5ml / day. The dosage of gel microspheres was 0.1g / L (based on nano-silicon). The total water volume in the tank was 18L. The gel microsphere material was packaged in mesh bags, divided into four portions, and evenly distributed in the central area of ​​the tank. The material was replaced every 3 days. The experimental results are as follows:

[0086] (1) Growth status of Vallisneria natans: During the cultivation process, the growth status of Vallisneria natans was tracked and photographed, mainly observing the changes in leaf length. Photos were taken and the leaf length data of Vallisneria natans were measured using ImageJ software. The leaf length distribution and growth rate of Vallisneria natans in each treatment group were compared. The results are as follows: Figure 3 (a)(b) During the six days of cultivation, the control group and Cu+ material group grew faster than the Cu-exposed group, and showed a significant length advantage on the 5th and 6th days. The Cu+Si group had an average growth of 42.4% higher than the Cu group.

[0087] (2) Zebrafish mortality rate: During the culture process, the number of zebrafish that died each day was counted, and the survival curve of the zebrafish over 14 days was plotted. Results are shown below. Figure 4 The final mortality rates of the Control group, Cu group, Cu+Si group, and Si group were 4%, 36%, 8%, and 44%, respectively, with a P value of 0.0123. Therefore, the mortality rates of zebrafish in the Cu group and the hydrogen-producing material group were significantly higher than those in the Control group and the Cu+Si group.

[0088] (3) Determination of Cu accumulation in zebrafish: After culture, three zebrafish from each of the Cu and Cu+Si groups were selected, weighed, and added with physiological saline at a volume nine times their fresh weight. The mixture was then ground at low temperature until the zebrafish were completely broken down. The resulting biological homogenate was centrifuged at 2500 r / min for 30 min. The supernatant was collected, and particulate matter was removed using a 4.5 μm filter membrane. After diluting twice, the Cu concentration was determined by ICP-MS. The results are shown below. Figure 5 After adding gel microspheres to the aquatic ecosystem, the amount of Cu accumulated in zebrafish was significantly reduced.

[0089] The above description of specific embodiments of the present invention does not limit the present invention. Those skilled in the art can make various changes or modifications based on the present invention, and as long as they do not depart from the spirit of the present invention, they should all fall within the scope of protection of the claims of the present invention.

Claims

1. The application of slow-release hydrogen-producing materials containing nano-silicon in aquatic ecosystem restoration, wherein the aquatic ecosystem restoration includes any one or a combination of mitigating the toxicity of heavy metal pollution, increasing the hydrogen content in the aquatic ecosystem, increasing the survival rate of zebrafish, and promoting the growth of aquatic plants. The sustained-release hydrogen production material is a gel microsphere containing nano-silicon. The gel microsphere contains 1-10 wt% sodium alginate, 0.05-15 wt% nano-silicon, and 1-10 wt% crosslinking agent, wherein the crosslinking agent is calcium chloride. The nano-silicon has a particle size of 20 nm-200 nm. The gel microsphere has a particle size of 1-10 mm. The nano-silicon is uniformly dispersed within the sodium alginate, and the gel microsphere has a layered structure inside. The continuous hydrogen production time of the gel microsphere containing 0.1 g of nano-silicon exceeds 80 h. The preparation method of the slow-release hydrogen production material includes the following steps: (1) After sterilizing a sodium alginate solution with a mass concentration of 2-5% (w / w) and cooling it to room temperature, add nano-silicon at a mass concentration of 0.3-0.5%wt of sodium alginate solution and stir at room temperature for 30-60 min at 500-600 r / min to obtain nano-silicon sodium alginate solution. (2) The nano-sized sodium alginate solution prepared in step (1) is added dropwise at a rate of 1 drop / second to a CaCl2 solution with a mass percentage of 2-5% at a volume ratio of 1-5:1, and allowed to stand for 5-10 minutes to obtain the solution.

2. The application as described in claim 1, characterized in that, The content of sodium alginate in the gel microspheres is 1-6 wt%.

3. The application as described in claim 1, characterized in that, The content of nano-silicon in the gel microspheres is 0.09-10 wt%.

4. The application as described in claim 1, characterized in that, The cross-linking agent content in the gel microspheres is 1-6 wt%.

5. The application as described in claim 1, characterized in that, The particle size of the nano-silicon is 50nm-100nm.

6. The application as described in claim 1, characterized in that, The particle size of the gel microspheres is 3-5 mm.

7. The application as described in claim 1, characterized in that, The continuous hydrogen production time of the gel microspheres containing 0.1g of nano-silicon exceeded 100h.

8. The application as described in any one of claims 1-6, characterized in that, The gel microspheres can adsorb heavy metals with an adsorption rate greater than 80%.

9. The application as described in claim 8, characterized in that, The gel microspheres can adsorb heavy metals with an adsorption rate greater than 85%.

10. The application as described in claim 8, characterized in that, The gel microspheres can adsorb heavy metal Cu.

11. The application as described in claim 1, characterized in that, The sodium alginate solution is prepared by adding sodium alginate to water and stirring at room temperature for no less than 6 hours with a magnetic stirring speed of 500-700 r / min until a viscous, transparent solution without white or pale yellow powder is obtained.

12. The application as described in claim 11, characterized in that, The sterilization temperature is 110℃ and the sterilization time is 20 minutes.

13. The application as described in claim 11, characterized in that, In step (1), the mixture is stirred until it is evenly dispersed and no powder floats, and the solution is brown and opaque.

14. The application as described in claim 11, characterized in that, The CaCl2 solution is prepared by adding calcium chloride to water and ultrasonically dispersing it until the calcium chloride is completely dissolved.

15. The application as described in claim 1, characterized in that, The dosage of the slow-release hydrogen-producing material is 0.1-10 g / L.

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