Method for fast enrichment of heavy metal ions in water by confining water

Abstract

The application discloses a method for fast enrichment of heavy metal ions in water by confined water, and belongs to the technical field of separation, analysis and detection. The method comprises the following steps: S1, preparing carbon nanofiber / carbon fiber; S2, loading the carbon nanofiber / carbon fiber obtained in S1 to prepare a needle tip device; and S3, extracting heavy metal ions in a solution by using the needle tip device obtained in S2. The method for fast enrichment of heavy metal ions in water by confined water is prepared by means of a vapor deposition method, water is confined in a nanometer space, heavy metal ions in water are extracted by confined water, and the heavy metal ions are desorbed by using the complexation of the heavy metal ions and EDTA, so that the green, non-toxic, simple-to-operate, fast and efficient extraction and enrichment of the heavy metal ions are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of separation and analysis detection technology, and particularly relates to a method for rapid enrichment of heavy metal ions in water by limited water. BACKGROUND

[0002] Nowadays, the development of single detection instrument for water body is relatively mature at home and abroad, but the instrument for online simultaneous detection of various pollutants in water body is almost invisible. The development from conventional laboratory offline detection to online on-site detection is imminent. The sensing technology rising in recent years makes the analysis of heavy metal ions develop towards the direction of portability, lightness and simplification, but also faces the bottleneck of current technology, and substantial breakthroughs are needed. The low content, multiple types and serious matrix interference of heavy metal elements in water body have great influence on the detection accuracy, and how to realize the green and efficient enrichment and rapid detection of trace heavy metal ions is the key.

[0003] The commonly used enrichment techniques for heavy metal ions in water body, such as solid-phase microextraction, solid-phase extraction and liquid-liquid extraction, have obvious deficiencies in the analysis of trace heavy metals, especially in situ, online and real-time analysis, due to the low mass transfer efficiency and extraction capacity. SUMMARY

[0004] The purpose of the present application is to provide a method for rapid enrichment of heavy metal ions in water by limited water, which realizes the stable and controllable liquid droplet manipulation of liquid phase extraction technology, maximizes the contact probability of target substances and extraction phase, and realizes the rapid, high-throughput and high-enrichment microextraction of heavy metals in water.

[0005] To achieve the above purpose, the present application provides a method for rapid enrichment of heavy metal ions in water by limited water, comprising the following steps:

[0006] S1, preparing carbon nanofiber / carbon fiber;

[0007] S2, loading the carbon nanofiber / carbon fiber obtained in S1 to prepare a needle tip device;

[0008] S3, using the needle tip device obtained in S2 to liquid phase nano-extract heavy metal ions in a solution.

[0009] Preferably, S1 comprises the following steps:

[0010] S11, pretreating carbon fiber to obtain acidified carbon fiber;

[0011] S12, the acidified carbon fiber is immersed in a catalyst solution for 10-14 hours to obtain a second carbon fiber, a pump, a filter bottle and a Buchner funnel are connected, a filter membrane is placed on the Buchner funnel, the second carbon fiber is cut into 3-4 cm to obtain a third carbon fiber, and the third carbon fiber is placed on the filter membrane, the third carbon fiber is eluted by the catalyst solution, after the third carbon fiber is completely dispersed, suction filtration is performed until the third carbon fiber is nearly dry, the third carbon fiber is taken out and dried at room temperature, and a deposited carbon fiber is obtained;

[0012] S13, the deposited carbon fiber is prepared into a carbon nanofiber / carbon fiber by a chemical vapor deposition method.

[0013] Preferably, the specific steps of S11 are as follows:

[0014] S111, the carbon fiber is wound on a self-made stainless steel frame, and is placed in a quartz boat and calcined at high temperature by using a tube furnace or a muffle furnace, the temperature rising rate of high-temperature calcination is 3-10 ℃ / min, the temperature is 450-500 ℃, and the time is 30-60 min, to obtain a first carbon fiber;

[0015] S112, the first carbon fiber is soaked in a concentrated nitric acid / sulfuric acid solution at normal temperature and pressure for 10-14 hours, and then repeatedly immersed in ultrapure water until the surface is neutral, and then dried in an oven, the drying temperature is 40-60 ℃, and the drying time is 1-3 hours, to obtain an acidified carbon fiber;

[0016] Preferably, in the concentrated nitric acid / sulfuric acid solution, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:3.

[0017] Preferably, in S12, the specific operation of preparing the catalyst solution is as follows: tetraethyl orthosilicate, P123, H2O, ethanol, hydrochloric acid and nickel nitrate are sequentially added according to a molar ratio of 1:(0.01-0.011):(9.2-9.4):(20-22):(0.01-0.1):(0.1-1), and after addition, stirring is performed at room temperature at a rotating speed of 400-450 rpm / min for 10-12 hours.

[0018] Preferably, the specific steps of S13 are as follows:

[0019] S131, the deposited carbon fiber is placed horizontally on a quartz boat, and is calcined at high temperature by using a tube furnace or a muffle furnace, the temperature of high-temperature calcination is 450-500 ℃, the temperature rising rate is 3-10 ℃ / min, and the time is 30-60 min, to obtain a fourth carbon fiber;

[0020] S132, the fourth carbon fiber is placed horizontally on a quartz boat, and is placed in a tube furnace, nitrogen is used as a protective gas, the temperature is raised to 550-650 ℃ at a rate of 3-10 ℃ / min, hydrogen is first introduced for high-temperature calcination, and then acetylene gas is introduced for high-temperature calcination, the total time of high-temperature calcination is 1-3 hours, and after the reaction is completed, the temperature is cooled to room temperature to obtain a carbon nanofiber / carbon fiber.

[0021] Preferably, S2 comprises the following steps:

[0022] S21, immerse the carbon nanofiber / carbon fiber obtained in S1 in methanol and perform ultrasonic treatment, after the ultrasonic treatment, use tweezers to pick up the carbon nanofiber / carbon fiber, wash the bottle with methanol, and then place in an oven and dry at 70°C for 5 min to obtain first carbon nanofiber / carbon fiber;

[0023] S22, use a millionth scale to weigh the original weight of the first carbon nanofiber / carbon fiber as A mg, use tweezers and scissors to peel off 50-60 carbon nanofibers / first carbon fibers, weigh the remaining fibers as B mg, calculate the weight of the peeled-off fibers as C mg, and C is 0.6-1.0 mg;

[0024] S23, immerse the peeled-off first carbon nanofiber / carbon fiber in methanol to make it gather into clusters, use tweezers to pick up the clusters and slowly pass them through the needle tip to load them, after the loading is completed, twist the needle tip back to the microsyringe to obtain a needle tip device.

[0025] Preferably, S3 comprises the following steps:

[0026] S31, push ultrapure water from the needle tip of the needle tip device prepared in S2 to limit the domain;

[0027] S32, push the heavy metal ion solution through the needle tip with a micro peristaltic pump to extract the heavy metal ions;

[0028] S33, push the EDTA desorption solution through the needle tip with a micro peristaltic pump to complete the desorption.

[0029] Preferably, in S32 and S33, the extraction time and the desorption time are both 5 s-5 min.

[0030] Preferably, in S32, the heavy metal ions in the heavy metal ion solution are one of Cu 2+ , Cd 2+ , Pb 2+ , Zn 2+ , Fe 3+ , Fe 2+ , and the concentration is 50-2500 ng / mL.

[0031] Preferably, in S33, the concentration of the EDTA desorption solution is 0.1-0.2 mM.

[0032] Therefore, the application adopts the above-mentioned method for fast enrichment of heavy metal ions in water by limiting water, prepares carbon nanofiber / carbon fiber by means of vapor deposition, successfully limits water in a nano space, extracts heavy metal ions in water by limiting water, and realizes green, non-toxic, simple operation, fast and efficient extraction and enrichment of heavy metal ions by desorption through complexation of heavy metal ions and EDTA.

[0033] The technical solutions of the application are further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 Figure 1 is a schematic diagram of a needle-point device for limiting water extraction of Cu according to an embodiment of the method for fast enrichment of heavy metal ions in water by limiting water of the application. 2+ Figure 2 is a graph of recovery rate change with sample concentration. DETAILED DESCRIPTION

[0035] The technical solutions of the application are further described in detail below with reference to the drawings and examples.

[0036] Unless otherwise defined, the technical terms or scientific terms used in the application shall have the usual meanings understood by those skilled in the art to which the application belongs.

[0037] Example 1

[0038] A method for fast enrichment of heavy metal ions in water by limiting water, comprising the following steps:

[0039] S1, preparing carbon nanofiber / carbon fiber, specifically comprising the following steps:

[0040] S11, obtaining acidified carbon fiber by pretreating carbon fiber, specifically comprising the following steps:

[0041] S111, winding 60 cm carbon fiber on a self-made stainless steel frame, placing it in a quartz boat, and calcining it in a muffle furnace at a high temperature, with a temperature rising rate of 5 ℃ / min to 450 ℃ for 30 min, to obtain first carbon fiber.

[0042] S112, immersing the first carbon fiber in a concentrated nitric acid / sulfuric acid solution at normal temperature and pressure for 12 h, then repeatedly immersing it in ultrapure water until the surface is neutral, and then placing it in an oven for drying at 40 ℃ for 2 h, to obtain acidified carbon fiber;

[0043] In the concentrated nitric acid / sulfuric acid solution, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:3.

[0044] S12, the acidified carbon fiber is immersed in the catalyst solution for 12 hours to obtain second carbon fiber, a pump, a filter bottle and a Buchner funnel are connected, a filter membrane is placed on the Buchner funnel, the second carbon fiber is cut into 3 cm to obtain third carbon fiber, and the third carbon fiber is placed on the filter membrane; the catalyst solution is used to rinse the third carbon fiber; after the third carbon fiber is completely dispersed, suction filtration is performed until the third carbon fiber is nearly dry, and the third carbon fiber is taken out and dried at room temperature to obtain deposited carbon fiber;

[0045] The specific operation of preparing the catalyst solution is as follows: tetraethyl orthosilicate, P123, H2O, ethanol, hydrochloric acid and nickel nitrate are sequentially added according to a molar ratio of 1: (0.0103): (9.36): (21.4): (0.04): (0.4), and stirring is performed at a rotation speed of 400 rpm / min for 12 hours at room temperature.

[0046] S13, the carbon nanofiber / carbon fiber is prepared by a chemical vapor deposition method, and the method specifically comprises the following steps:

[0047] S131, the deposited carbon fiber is placed horizontally on a quartz boat, and high-temperature calcination is performed by using a muffle furnace, the temperature is raised to 450 DEG C at a temperature raising rate of 5 DEG C / min, and the temperature is kept for 30 min to obtain fourth carbon fiber.

[0048] S132, the fourth carbon fiber is placed horizontally on a quartz boat, and is placed in the center of a tube furnace; nitrogen gas with a flow rate of 155 cc / min is introduced as a protective gas; the temperature is raised to 600 DEG C at a rate of 5 DEG C / min; then, hydrogen gas with a flow rate of 25 cc / min is introduced for high-temperature calcination for 30 min; then, acetylene gas is introduced for high-temperature calcination for 30 min; after the reaction is completed, the temperature is cooled to room temperature to obtain carbon nanofiber / carbon fiber.

[0049] S2, the carbon nanofiber / carbon fiber obtained in S1 is loaded to prepare a needle tip device, and the method specifically comprises the following steps:

[0050] S21, the carbon nanofiber / carbon fiber obtained in S1 is immersed in methanol, and ultrasonic treatment is performed for 5 min at the lowest energy; the carbon nanofiber / carbon fiber after ultrasonic treatment is picked up by using tweezers, and then rinsed by using a methanol washing bottle; then, the carbon nanofiber / carbon fiber is placed in an oven and dried at 70 DEG C for 5 min to obtain first carbon nanofiber / carbon fiber.

[0051] S22, the original weight of the first carbon nanofiber / carbon fiber is weighed by using a one-in-ten-thousand balance, and is 2.0 mg; 50 first carbon nanofibers / carbon fibers are peeled off by using tweezers and scissors; the remaining fibers are weighed, and the weight is 1.2 mg; the weight of the peeled-off fibers is calculated, and is 0.8 mg.

[0052] S23, the peeled-off carbon nanofiber / first carbon fiber is immersed in methanol, and is gathered into clusters; the carbon nanofiber / first carbon fiber is picked up by using tweezers, and is slowly inserted into the needle tip to be loaded; after the loading is completed, the needle tip is twisted back to the micro syringe to obtain a needle tip device.

[0053] S3, extracting heavy metal ions from the liquid phase nanoextraction solution of the tip device obtained in S2, specifically comprising the following steps:

[0054] S31, pushing 100 μL ultrapure water out of the tip of the tip device prepared in S2 for confinement;

[0055] S32, pushing 500 ng / mL Cu 2+ solution through the tip at a flow rate of 50 μL / min by using a micro peristaltic pump, extracting Cu 2+ , and the extraction time is 30 s;

[0056] S33, pushing 0.1 mM EDTA desorption solution through the tip at a flow rate of 50 μL / min by using a micro peristaltic pump, completing desorption, and the desorption time is 30 s.

[0057] Example Two

[0058] Example Two is different from Example One in that the concentration of Cu 2+ solution is 50 ng / mL.

[0059] Example Three

[0060] Example Three is different from Example One in that the concentration of Cu 2+ solution is 100 ng / mL.

[0061] Example Four

[0062] Example Four is different from Example One in that the concentration of Cu 2+ solution is 250 ng / mL.

[0063] Example Five

[0064] Example Five is different from Example One in that the concentration of Cu 2+ solution is 1000 ng / mL.

[0065] Example Six

[0066] Example Six is different from Example One in that the concentration of Cu 2+ solution is 1500 ng / mL.

[0067] Example Seven

[0068] Example Seven is different from Example One in that the concentration of Cu 2+ solution is 2000 ng / mL.

[0069] Example Eight

[0070] Example Eight is different from Example One in that the concentration of Cu 2+ solution is 2500 ng / mL.

[0071] Example 9

[0072] The difference between Example 9 and Example 1 is that the extraction time is 20 seconds.

[0073] Example 10

[0074] The difference between Example 10 and Example 1 is that the heavy metal ion solution is Cd. 2+ The solution was extracted for 20 seconds.

[0075] Example 11

[0076] The difference between Example 11 and Example 1 is that the heavy metal ion solution is Pb. 2+ The solution was extracted for 20 seconds.

[0077] Example 12

[0078] The difference between Example 12 and Example 1 is that the heavy metal ion solution is Zn. 2+ The solution was extracted for 20 seconds.

[0079] Example 13

[0080] The difference between Example 13 and Example 1 is that the heavy metal ion solution is Fe. 3+ The solution was extracted for 20 seconds.

[0081] Example 14

[0082] The difference between Example 14 and Example 1 is that the heavy metal ion solution is Fe. 2+ The solution was extracted for 20 seconds.

[0083] The content of heavy metal ions in the desorption solution was analyzed by HPLC-MS / MS, and the recovery rate was calculated according to the following formula:

[0084] ;

[0085] Where R is the recovery rate (%), C is the heavy metal ion content in the desorption solution (ng / mL), and C0 is the initial heavy metal ion content (ng / mL).

[0086] Comparing different initial Cu values ​​in Examples 1 to 8 2+ Confined water extraction of Cu using a needle tip device at a certain concentration 2+ Recovery rate, results as follows Figure 1 As shown. By Figure 1 It can be seen that Cu 2+ The recovery rate was above 83% with an RSD of <15% when the concentration was 50-2500 ng / mL. The upper limit of the linear range of this method is 2500 ng / mL, therefore the maximum concentration of heavy metal ions is 2500 ng / mL.

[0087] The extraction effects of different heavy metal ions in comparative examples 9 to 14 were compared. When the extraction time was 20 s, the recovery rates of Cu 2+ , Cd 2+ , Pb 2+ , Zn 2+ , Fe 3+ , Fe 2+ were 43.93-98.27%, and the RSD was less than 8%. Among them, the extraction effect of the needle tip device on Zn 2+ was the best, with a recovery rate of 98.27%, and the extraction effect on Fe 2+ was the worst, with a recovery rate of 43.93%. This shows that the liquid phase nano-extraction method of the needle tip device has good extraction effects on Cu 2+ , Cd 2+ , Pb 2+ , Zn 2+ , Fe 3+ , Fe 2+ , and can be widely applied to the detection of heavy metal ions.

[0088] Therefore, the method for rapidly enriching heavy metal ions in water in the limited domain is adopted, the liquid phase extraction technology droplet manipulation is stable and controllable, the contact probability of the target and the extraction phase is maximized, and the rapid, high-throughput, high-enrichment micro-extraction of heavy metals in water is realized.

[0089] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for fast enrichment of heavy metal ions in water by confined water, characterized in that, It comprises the following steps: S1, preparing carbon nanofiber / carbon fiber; the S1 comprises the following steps: S11, carbon fiber pretreatment to obtain acidified carbon fiber; S12, the acidified carbon fiber is immersed in the catalyst solution for 10-14h to obtain the second carbon fiber, a filter membrane is placed on the Buchner funnel, the second carbon fiber is cut into 3-4cm to obtain the third carbon fiber, and then the third carbon fiber is placed on the filter membrane; the catalyst solution is used to elute the third carbon fiber; after the third carbon fiber is completely dispersed, suction filtration is carried out to a near-dry state; the third carbon fiber is taken out and dried at room temperature to obtain the deposited carbon fiber; the catalyst solution is composed of tetraethyl orthosilicate, P123, H2O, ethanol, hydrochloric acid and nickel nitrate; S13, the deposited carbon fiber is prepared into carbon nanofiber / carbon fiber by chemical vapor deposition method; S2, loading the carbon nanofiber / carbon fiber obtained in S1 to prepare a needle tip device; the S2 comprises the following steps: S21, the carbon nanofiber / carbon fiber obtained in S1 is immersed in methanol and ultrasonicated; after ultrasonic treatment, the carbon nanofiber / carbon fiber is picked up with tweezers, washed with methanol, and then dried in an oven at 70℃ for 5min to obtain the first carbon nanofiber / carbon fiber; S22, the original weight of the first carbon nanofiber / carbon fiber is weighed with a one-hundredth scale; 50-60 first carbon nanofiber / carbon fibers are peeled off with tweezers and scissors; the remaining fibers are weighed, and the weight of the peeled fibers is calculated; S23, the peeled first carbon nanofiber / carbon fiber is immersed in methanol to form clusters; the clusters are picked up with tweezers and slowly inserted into the needle tip to load; after loading, the needle tip is twisted back to the microsyringe to obtain a needle tip device; S3, using the needle tip device obtained in S2 to extract heavy metal ions in a solution; the S3 comprises the following steps: S31, pushing the ultrapure water from the needle tip of the needle tip device prepared in S2 to limit; S32, push the heavy metal ion solution through the needle tip with a micro peristaltic pump to extract the heavy metal ions; the heavy metal ions in the heavy metal ion solution are one of Cu 2+ , Cd 2+ , Pb 2+ , Zn 2+ , Fe 3+ , Fe 2+ ​ S33, pushing the EDTA desorption solution through the needle tip with a micro peristaltic pump to complete desorption.

2. The method of claim 1, wherein, The specific steps of S11 are as follows: S111, winding the carbon fiber on a self-made stainless steel frame, placing it in a quartz boat, and high-temperature calcining with a tube furnace or a muffle furnace; the heating rate of high-temperature calcining is 3-10℃ / min, the temperature is 450-500℃, and the time is 30-60min to obtain the first carbon fiber; S112, immersing the first carbon fiber in a mixed solution of concentrated nitric acid and concentrated sulfuric acid at normal temperature and pressure for 10-14h, and then repeatedly immersing in ultrapure water until the surface is neutral; drying in an oven at a drying temperature of 40-60℃ for 1-3h to obtain the acidified carbon fiber; In the mixed solution of concentrated nitric acid and concentrated sulfuric acid, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:

3.

3. The method of claim 2, wherein, In S12, the specific operation of preparing the catalyst solution is as follows: tetraethyl orthosilicate, P123, H2O, ethanol, hydrochloric acid, and nickel nitrate are sequentially added according to a molar ratio of 1:(0.01-0.011):(9.2-9.4):(20-22):(0.01-0.1):(0.1-1), and then stirred at a rotation speed of 400-450 rpm / min at room temperature for 10-12 h.

4. The method of claim 3, wherein, The specific steps of S13 are as follows: S131, the deposited carbon fibers are placed transversely on a quartz boat, and then high-temperature calcination is performed in a tube furnace or a muffle furnace, the high-temperature calcination temperature is 450-500℃, the temperature rising rate is 3-10℃ / min, and the time is 30-60 min, to obtain fourth carbon fibers; S132, the fourth carbon fibers are placed transversely on a quartz boat, and then placed in a tube furnace, nitrogen is used as a protective gas, the temperature is raised to 550-650℃ at a rate of 3-10℃ / min, hydrogen is introduced for high-temperature calcination, and then acetylene gas is introduced for high-temperature calcination, the total high-temperature calcination time is 1-3 h, and then cooled to room temperature to obtain carbon nanofibers / carbon fibers.

5. The method of claim 4, wherein, In S32 and S33, the extraction time and the desorption time are both 5 s-5 min.

6. The method of claim 5, wherein, In S32, the concentration of heavy metal ions in the heavy metal ion solution is 50-2500 ng / mL.

7. The method of claim 6, wherein, In S33, the concentration of the EDTA desorption solution is 0.1-0.2 mM.

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