Combined extraction method of diatom and plant silicon body in siliceous sediment

Abstract

The invention provides a combined extraction method of diatom and phyllosilicate in siliceous sediment, and relates to the technical field of combined extraction of diatom and phyllosilicate, and the method comprises the following steps: dispersing a sample by using a hydrogen peroxide solution, carrying out ultrasonic filtration, and removing calcium in a solid sample by using hydrochloric acid; the method has the advantages that ineffective components in the sample can be removed in the ultrasonic filtering process, the use of heavy liquid in the traditional extraction method is avoided, the use amount of hydrochloric acid in the extraction process is effectively reduced, the cost of the extraction process is greatly reduced, and the extraction process is simplified. By adopting the mode, the combined extraction method for the diatom and the plant silicon body in the siliceous sediment, which is provided by the invention, is high in extraction efficiency, simple in operation and simple in process.

Description

Technical Field

[0001] The invention relates to the technical field of combined extraction of diatoms and phytoliths, and in particular to a method for combined extraction of diatoms and phytoliths in siliceous sediments. Background Art

[0002] Diatoms are a type of single-celled plant with chromatophores. They exist in groups in almost all aquatic environments, and are widely found in rivers, lakes, oceans, and other water environments. They are characterized by wide distribution, many species, large numbers, and rapid reproduction. The distribution and composition of diatom species are very sensitive to indicators such as water salinity, depth, temperature, and nutritional changes. Different combinations of diatom species can indicate different sedimentary environments (lakes, deltas, continental shelves, deep seas, etc.). Therefore, diatoms are considered to be one of the effective indicators for judging changes in sedimentary environments in rivers, lakes, and oceans.

[0003] Plant silicates (phytoliths for short) are amorphous silica particles that are precipitated in plants after plants absorb soluble monosilicic acid from the soil through their roots during their growth. Once formed in the plant body, the size ranges from 20 to 200 μm, and some diameters exceed 2 mm. Their physical and chemical properties are stable, and they have the characteristics of corrosion resistance, high temperature resistance, and in-situ deposition. Phytoliths are widely used in the research of paleoenvironmental changes, sedimentary evolution, and botany. According to the material composition analysis of diatoms and phytoliths, the main components of the two are the same, both of which are amorphous hydrous siliceous shells / external walls. Therefore, in the prior art, diatoms and phytoliths are extracted by removing organic matter, removing carbonates, removing calcium, heavy liquid flotation, and centrifugal purification. However, when the above-mentioned treatment method is used to treat marine sediments with high carbonate and silica content, the treated samples still contain a certain amount of quartz sand impurities, and the treatment effect is not good.

[0004] In view of this, it is necessary to design an improved method for the combined extraction of diatoms and phytoliths from siliceous sediments to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a method for the combined extraction of diatoms and phytoliths from siliceous sediments.

[0006] To achieve the above-mentioned object of the invention, the present invention provides a method for the combined extraction of diatoms and phytoliths from siliceous sediments, comprising the following steps:

[0007] The samples containing diatoms and phytoliths are dried and ground to obtain pulverized samples of silt-grade;

[0008] The crushed sample is added into a hydrogen peroxide solution to fully disperse the particles, and then the solution containing the sample is filtered through a mesh sieve with a pore size of 200 μm and a mesh sieve with a pore size of 10 μm under ultrasonic conditions to obtain a valid sample with a particle size of 10-200 μm;

[0009] The solid remaining on the 10 μm mesh after filtration was added to dilute hydrochloric acid, reacted for 24 hours under stirring conditions, and then centrifuged, washed, and dried to obtain solid diatoms and phytoliths.

[0010] Preferably, the centrifugal conditions are: rotation speed 4000 rpm, time 3 min.

[0011] Preferably, the mass percentage of dilute hydrochloric acid is 20%.

[0012] Preferably, the ratio of the mass of the solid to the volume of the dilute hydrochloric acid is 1:3.

[0013] Preferably, the mass percentage of the hydrogen peroxide solution is 12%.

[0014] Preferably, the amount of hydrogen peroxide solution added is 20 mL.

[0015] Preferably, the power of ultrasound is 300W, the frequency is 60 kHz, and the time is 3 min.

[0016] Preferably, the drying temperature is an oven temperature of 80° C. and the drying time is 1 hour.

[0017] Preferably, the sample containing diatoms and phytoliths is seabed sediment collected from the deep sea.

[0018] The beneficial effects of the present invention are:

[0019] The combined extraction method of diatoms and phytoliths in siliceous sediments provided by the present invention uses hydrogen peroxide solution to disperse the sample, then performs ultrasonic filtration, and then uses hydrochloric acid to remove calcium in the solid sample. Ineffective components in the sample can be removed during the ultrasonic filtration process, which not only avoids the use of heavy liquid in traditional extraction methods, but also effectively reduces the amount of hydrochloric acid used in the extraction process, greatly reduces the cost of the extraction process, and simplifies the extraction process. In the above manner, a combined extraction method of diatoms and phytoliths in siliceous sediments with high extraction efficiency, simple operation, and simple process is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A flow chart of the combined extraction method of diatoms and phytoliths from siliceous sediments provided by the present invention;

[0021] Figure 2 A flow chart of the combined extraction method of diatoms and phytoliths from siliceous sediments provided in Comparative Examples 1-2 of the present invention;

[0022] Figure 3 Part of the microscope analysis results of Example 1 of the present invention;

[0023] Figure 4 These are typical microscope images of diatoms and phytoliths;

[0024] Figure 5 This is the microscope analysis result of Example 1 of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0027] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0028] See also Figure 1 As shown, the combined extraction method of diatoms and phytoliths from siliceous sediments provided by the present invention comprises the following steps:

[0029] The samples containing diatoms and phytoliths were dried and ground to obtain pulverized samples of silt-grade (particle size range less than 0.002 mm);

[0030] The crushed sample is added into a hydrogen peroxide solution to fully disperse the particles, and then the solution containing the sample is filtered through a mesh sieve with a pore size of 200 μm and a mesh sieve with a pore size of 10 μm under ultrasonic conditions to obtain a valid sample with a particle size of 10-200 μm;

[0031] The solids left on the 10μm mesh after filtration are added to dilute hydrochloric acid and fully reacted for 24 hours under stirring conditions to remove carbonates, organic matter and calcium in the sample, and then centrifuged, washed and dried to obtain solid diatoms and phytoliths. During the application process, a suitable dispersant (such as acetone, etc.) can be selected as needed to disperse the solid diatoms and phytoliths for analysis and identification.

[0032] In the above technical scheme, by filtering under ultrasonic conditions, on the one hand, the invalid impurities (clay particles, silt, etc.) in the sample can be removed in advance by physical screening, and the target object can be effectively enriched, which greatly reduces the time required for extraction. On the other hand, the ultrasonic collaborative filtration method can facilitate the full dispersion of solid particles in the solution, facilitate the full contact between the particulate matter and the hydrogen peroxide solution, and ensure the high-purity extraction of the target object. At the same time, the amount of hydrochloric acid used in the subsequent treatment process is reduced, saving the cost of reagent use; by filtering with a pore size of 200μm and a pore size of 10μm, the invalid components in the sample can be effectively removed, avoiding the invalid components from affecting the subsequent extraction process and then affecting the purity of the target; furthermore, the reduction in the amount of hydrochloric acid used can reduce its corrosion loss to the effective components of the source, and the results obtained are more ideal.

[0033] Secondly, by using hydrogen peroxide solution to disperse the sample, ultrasonic filtration, and then using hydrochloric acid to remove calcium from the solid sample, the ineffective components in the sample can be removed during the ultrasonic filtration process, which not only avoids the use of heavy liquid in traditional extraction methods, but also effectively reduces the amount of hydrochloric acid used in the extraction process, greatly reduces the cost of the extraction process, and simplifies the extraction process. In particular, adding hydrochloric acid in the later stage of extraction can shorten the contact time between hydrochloric acid and effective ingredients during the extraction process, and delay the corrosion loss of the acidic reagent (hydrochloric acid) to the effective ingredients diatoms and phytoliths.

[0034] As an embodiment of the present invention, the sample containing diatoms and phytoliths is seabed sediments collected from the deep sea, and the impurity components are mainly oceanic clay deposits, and the particle size thereof is mostly less than 10 μm. Therefore, most of the impurities can be removed by screening with a mesh sieve, thereby greatly improving the extraction purity and acquisition efficiency.

[0035] As an embodiment of the present invention, the centrifugal conditions are: rotation speed 4000 rpm, time 3 min.

[0036] As an embodiment of the present invention, the mass percentage of dilute hydrochloric acid is 20%, and the ratio of solid mass to volume of dilute hydrochloric acid is 1:3. It should be noted that the stirring in the above technical solution is mechanical stirring, the purpose of which is to make each reactant fully contact.

[0037] As an embodiment of the present invention, the power of ultrasound is 300W, the frequency is 60kH, and the time is 3min.

[0038] As an embodiment of the present invention, the mass percentage of the hydrogen peroxide solution is 12%.

[0039] As an embodiment of the present invention, the drying temperature is 80° C. in the oven setting temperature, and the drying time is 1 hour.

[0040] The combined extraction method of diatoms and phytoliths from siliceous sediments proposed by the present invention is further described below in conjunction with specific embodiments:

[0041] Example 1

[0042] This embodiment provides a method for the combined extraction of diatoms and phytoliths from siliceous sediments, and the specific steps are as follows:

[0043] A sample with a dry weight of 10 g (specifically, a marine sediment core) was dried and ground to obtain a pulverized sample of silt grade (particle size range greater than 0.0039 mm);

[0044] The crushed sample was added into 20 mL of 12% by mass hydrogen peroxide solution to fully disperse the particles, and then the solution containing the sample was filtered through a mesh sieve with a pore size of 200 μm and a mesh sieve with a pore size of 10 μm under ultrasonic conditions to obtain a valid sample with a particle size of 10-200 μm; wherein the ultrasonic power was 300 W, the frequency was 60 kHz, and the time was 3 min;

[0045] The solids remaining on the 10 μm mesh after filtration were added to 10 mL of 20% by mass dilute hydrochloric acid, and stirred with a glass stirring rod for 24 hours; the solid matter after the reaction was washed with deionized water for several times until the supernatant was neutral (pH=7), and the solution was centrifuged at 4000 rpm for 3 minutes, the solid part was collected, and dried in an oven at 80°C for 6 minutes to obtain solid diatoms and phytoliths;

[0046] The solid diatoms and phytoliths mentioned above were added to acetone and analyzed and identified using a microscope. Some of the analysis results are as follows: Figure 3 As shown, compare it with typical pictures of diatoms and phytoliths Figure 4 In contrast, diatoms have a variety of morphologies, including round, needle-shaped, linear, boat-shaped, etc. Phytoliths also show diversity in morphology, including weak tooth-shaped, multi-tooth-shaped, dumbbell-shaped, rod-shaped, pointed, tooth-shaped, and cap-shaped, etc. Figure 4 The circular frame in the middle is round diatom, and the rectangular frame is boat-shaped diatom. Figure 3 Phytoliths of various shapes can be clearly seen, and the results show that the method proposed by the present invention can effectively extract diatoms and phytoliths in sediment samples.

[0047] During the analysis of this embodiment, the observation results under the same field of view of the microscope are as follows: Figure 5 As shown, diatoms (shown in the circular frame marked part) and phytoliths (shown in the rectangular frame marked part) can be seen at the same time in the figure. This result further verifies that the purification method proposed in the present invention can achieve the purpose of simultaneously extracting diatoms and phytoliths.

[0048] Comparative Example 1

[0049] This comparative example provides a method for extracting phytoliths from siliceous sediments. The extraction process is as follows: Figure 2 As shown, the specific steps are as follows:

[0050] A sample with a dry weight of 10 g was added to 100 mL of deionized water and 100 mL of a 12% by mass hydrogen peroxide solution to decompose the organic matter in the sample; under ultrasonic conditions, the sediment particles in the solution after the reaction were dispersed as much as possible;

[0051] After the ultrasonic treatment, 100 mL of 20% hydrochloric acid was added to the solution to remove iron and calcium from the sediment particles. Then, solids with a particle size of 10-100 μm were selected by sieving and sedimentation, and floated with a heavy liquid with a specific gravity of 2.3. The power of the ultrasonic treatment was 150 W, the frequency was 20 kHz, and the time was 10 min. The heavy liquid was specifically a zinc iodide solution (a mixed solution after the reaction of KI+Zn+HI), and the floatation time was 4 h.

[0052] Collect the solution after flotation, and add 500 mL of 20% by mass acetic acid solution to separate the phytoliths from the heavy liquid;

[0053] The flotation solution after centrifugation is centrifuged at a speed of 3000 rpm for 3 minutes. The precipitate is washed with deionized water several times during the centrifugation process until the supernatant is neutral (pH = 7); the supernatant is poured out, and the solution containing solids at the bottom is dried in an oven at 80°C for 60 minutes to obtain a solid sample; the solid sample is added to acetone and analyzed and identified using a microscope.

[0054] During the experiment, in order to improve the accuracy of the experiment, 10 samples were selected for comparison experiments. All 10 samples were from sediment cores in the Philippine waters (134.789546E, 17.879359N). Under the extraction conditions of Example 1 and Comparative Example 1, the extraction results of phytoliths are shown in Table 1. It can be seen from the data in Table 1 that the extraction method proposed in the present invention can effectively extract phytoliths from sediment samples.

[0055] Table 1 Extraction results of phytoliths in Example 1 and Comparative Example 1

[0056] Sample No. Number of phytoliths in Example 1 (pieces / sample) Number of phytoliths in Comparative Example 1 (pcs / sample) 1 176 86 2 258 123 3 38 0 4 221 79 5 276 107 6 189 72 7 176 52 8 247 48 9 238 85 10 196 65

[0057] Comparative Example 2

[0058] This comparative example provides a method for extracting diatoms from siliceous sediments. The extraction process is as follows: Figure 2 As shown, the specific steps are as follows:

[0059] A sample with a dry weight of 10 g was added to 20 mL of a 12% hydrogen peroxide solution to decompose the organic matter in the sample; then, the solid was washed with deionized water several times until the supernatant was neutral (pH = 7), and then 20 mL of 20% hydrochloric acid was added and reacted for 24 hours under stirring;

[0060] The solid matter after the reaction with hydrochloric acid was washed with deionized water several times until the supernatant was neutral (pH=7). After washing, the solid part was dried;

[0061] After the solid sample is floated with a heavy liquid having a specific gravity of 2.4, the solution after the floatation is filtered with a 10 μm mesh under ultrasonic conditions; after filtration, the solution is centrifuged at a speed of 3000 rpm for 3 minutes, the supernatant is poured out, and the solution containing solids at the bottom is dried in an oven at 80°C for 60 minutes to obtain a solid sample; the solid sample is added to acetone and analyzed and identified with a microscope. The ultrasonic power is 300W, the frequency is 60kH, and the time is 1h; the heavy liquid is specifically a zinc iodide solution (a mixed solution after the reaction of KI+Zn+HI), and the flotation time is 4h.

[0062] Under the extraction conditions of Example 1 and Comparative Example 2, the extraction results of diatoms are shown in Table 2. Combining the extraction results of Tables 1-2, it can be seen that the extraction method proposed in the present invention can effectively realize the joint extraction of diatoms and phytoliths in siliceous sediments. This is because: the extraction method proposed in the present invention can effectively remove clay impurities in the sample by filtering under ultrasonic conditions first. In addition, hydrochloric acid is added after most of the impurities are removed. Compared with the traditional extraction method (Comparative Examples 1-2), the amount of hydrochloric acid used can be greatly reduced, the addition time of hydrochloric acid is delayed, the contact time of hydrochloric acid with diatoms and phytoliths in the sample during the extraction process is shortened, and the corrosion loss of the effective ingredients diatoms and phytoliths by the acidic reagent (hydrochloric acid) is delayed. The results are more ideal. Since the main component of deep-sea clay is clay (more than 90%), the extraction method of the present invention is particularly suitable for deep-sea clay sediments.

[0063] Table 2 Extraction results of diatoms in Example 1 and Comparative Example 2

[0064] Sample No. Number of diatoms in Example 1 (pieces / sample) The number of diatoms in comparative example 2 (pieces / sample) 1 7219 2848 2 9426 3587 3 43 0 4 449 52 5 2453 584 6 4216 723 7 3120 527 8 4986 1236 9 8874 2236 10 12349 3349

[0065] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for the combined extraction of diatoms and phytoliths from siliceous sediments, characterized in that: The steps include: The samples containing diatoms and phytoliths are dried and ground to obtain pulverized samples of silt-grade; The crushed sample is added into a hydrogen peroxide solution to fully disperse the particles, and then the solution containing the sample is filtered through a mesh sieve with a pore size of 200 μm and a mesh sieve with a pore size of 10 μm under ultrasonic conditions to obtain a valid sample with a particle size of 10-200 μm; The solid remaining on the 10 μm mesh after filtration was added to dilute hydrochloric acid, reacted for 24 hours under stirring conditions, and then centrifuged, washed, and dried to obtain solid diatoms and phytoliths.

2. The combined extraction method according to claim 1, characterized in that: The centrifugal conditions were: speed 4000 rpm, time 3 min.

3. The combined extraction method according to claim 1, characterized in that: The mass percentage of dilute hydrochloric acid is 20%.

4. The combined extraction method according to claim 1 or 3, characterized in that: The ratio of the mass of solid to the volume of dilute hydrochloric acid is 1:

3.

5. The combined extraction method according to claim 1, characterized in that: The mass percentage of the hydrogen peroxide solution is 12%.

6. The combined extraction method according to claim 1 or 5, characterized in that: The amount of hydrogen peroxide solution added was 20 mL.

7. The combined extraction method according to claim 1, characterized in that: The power of ultrasound was 300W, the frequency was 60 kHz, and the time was 3 min.

8. The combined extraction method according to claim 1, characterized in that: The drying temperature is 80°C in the oven and the drying time is 1h.

9. The combined extraction method according to claim 1, characterized in that: The samples containing diatoms and phytoliths were seafloor sediments collected from the deep sea.

Images