CN113740369B - Reduction method for detecting heavy metal ions based on in-situ low-field nuclear magnetic resonance relaxation method - Google Patents
Reduction method for detecting heavy metal ions based on in-situ low-field nuclear magnetic resonance relaxation method Download PDFInfo
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- G01N24/00—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects
- G01N24/08—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects by using nuclear magnetic resonance
- G01N24/088—Assessment or manipulation of a chemical or biochemical reaction, e.g. verification whether a chemical reaction occurred or whether a ligand binds to a receptor in drug screening or assessing reaction kinetics
Abstract
The invention discloses a new method for detecting heavy metal ions by reduction based on an in-situ low-field nuclear magnetic resonance technology, namely, paramagnetic ion concentration and proton transverse relaxation rate (1/T) 2 ) Linear relation between the two, through using CPMG pulse sequence, through the real-time monitoring heavy metal ion reduction in-situ illumination in-process T 2 And (3) rapidly detecting the increase of the paramagnetic ion concentration, thereby further representing the reduction efficiency of heavy metal ions. Meanwhile, the method uses a SE-SPI layer selection sequence to monitor the reduction conditions of heavy metal ions at different layers of the reaction liquid in real time. The method is simple to operate, does not need to pretreat the raw solution and separate products, and has low cost and high accuracy. The method is expected to be popularized in the monitoring aspect of removing other heavy metal ions.
Description
Technical Field
The invention belongs to the technical field of low-field nuclear magnetic resonance, relates to detection of heavy metal ion treatment technology, and particularly relates to a method for detecting a chemical reaction of heavy metal ions in real time by an in-situ low-field nuclear magnetic resonance relaxation method.
Background
Heavy metals (chromium, mercury, lead, etc.) have been used by humans for thousands of years, and in the last few years the rapid development of industry and population has also led to the rise ofThe more people are exposed to heavy metals. Hexavalent chromium (Cr (VI)) is a common surface and groundwater contaminant among all toxic heavy metal ions. It has acute toxicity to most organisms, strong carcinogenicity, and high solubility in water. The World Health Organization (WHO) prescribes that the Cr (VI) content in the water body is not higher than 0.05mg/L. Therefore, for the health of the global organism, it is important to remove Cr (VI) or reduce the concentration thereof in the water body. Unlike common heavy metals such as lead, cadmium and copper, chromium exists mainly in two forms, namely trivalent chromium (III) with low toxicity and hexavalent chromium (VI) with high toxicity. At present, various treatment methods for wastewater containing Cr (VI) have been developed, wherein reduction of Cr (VI) to Cr (III) is one of the most effective methods for treating wastewater containing Cr (VI) because Cr (III) is less toxic and is easily available as Cr (OH) 3 Is precipitated in the form of a solid waste, and is convenient to remove. In recent years, photocatalytic technology using solar-chemical energy conversion has been considered as a clean, efficient, low-cost and harmless product-free method for reducing Cr (VI) to Cr (III).
Currently, ultraviolet spectrophotometry or atomic absorption spectrometry is commonly used to quantitatively analyze the concentration of heavy metal ions. However, ultraviolet spectrophotometry can only detect ions having an optical absorption band in the ultraviolet-visible region. Therefore, colorless heavy metal ions cannot be analyzed by ultraviolet spectrophotometry without color development. In addition, the analysis result may be subjected to other coexisting ions (e.g., mo 6+ 、Hg + 、Hg 2+ 、V 5+ 、Fe 3+ ) Is a part of the interference of the (c). Atomic absorption spectrometry has the advantage of element selectivity, but has a high operating cost. Meanwhile, in the photocatalytic Cr (VI) reduction process, the distance of the light source can influence the Cr (VI) reduction efficiency, and the conditions of reducing Cr (VI) to Cr (III) at various layers of the cross section at different distances from the light source are shown. At present, the traditional ultraviolet spectrophotometry and atomic absorption spectrometry cannot realize the research on Cr (VI) reduction processes at different layers. Therefore, the development of a novel rapid, simple, low-cost, accurate and pretreatment-free heavy metal ion concentration quantitative method has great significance for evaluating the heavy metal reduction performance,meanwhile, the method can detect the reaction solution at different layers and has great value in researching the heavy metal reduction process.
Disclosure of Invention
The invention aims to overcome the defects in the existing detection method and designs a rapid, simple, low-cost, accurate and pretreatment-free quantitative detection method for heavy metal reduction. The invention adopts a low-field nuclear magnetic resonance relaxation method to realize rapid detection of paramagnetic ions, simultaneously detects the photocatalytic reduction process in real time through an in-situ illumination device, realizes a method for representing reduction performance, and monitors the reduction conditions of heavy metal ions at different layers of the reaction liquid in real time through the same in-situ illumination device. The method has the advantages of rapidness, real time, low cost and no need of pretreatment, well eliminates the interference of other ions, and realizes the in-situ detection of the reaction solution reduction process in different cross sections for the first time.
The invention is based on the in-situ low-field nuclear magnetic resonance relaxation method to detect heavy metal ions, and utilizes the linear relation between paramagnetic ion concentration and proton transverse relaxation rate to monitor T in the process of heavy metal ion reduction (Cr (VI) reduction) in real time by using CPMG pulse sequence and in-situ illumination 2 Rapidly detecting the increase of the paramagnetic ion (Cr (III)) concentration, and further characterizing the reduction efficiency of heavy metal ions (Cr (VI)); and simultaneously, a SE-SPI layer selection sequence is used for monitoring the reduction conditions of heavy metal ions (Cr (VI)) at different layers of the reaction liquid in real time. The specific process is as follows:
(1) Adding the suspension filled with the catalyst powder and the heavy metal ion solution into a matched low-field nuclear magnetic tube, and carrying out ultrasonic homogenization;
(2) The in-situ light source equipment is assembled, a nuclear magnetic tube filled with a sample to be tested is placed in a cavity of a low-field nuclear magnetic resonance spectrometer, and light is introduced into the nuclear magnetic tube through an optical fiber;
(3) System T was performed using the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence 2 And (5) detecting the change condition of the value along with illumination time in situ.
(4) Different systems are realized by using Spin Echo-Single Point Imaging (SE-SPI) pulse sequencesLayer T 2 And (5) detecting the change condition of the value along with illumination time in situ.
In the invention, the adding amount of the catalyst powder is 0.5 mg-10 mg, the volume of the solution added with heavy metal ions is 1 mL-2 mL, and the light source and the nuclear magnetic tube are connected by optical fibers;
in the invention, the whole in-situ test process does not need to separate products;
in the invention, the diameter of the low-field nuclear magnetic tube is 10mm, the height is 100mm, and the Cr (VI) solution is added to the tube at a concentration of 1 mg/L-20 mg/L;
in the invention, the optical fiber used is a customized fiber bundle without metal wrapping;
according to the invention, the quantitative detection of the increase of the paramagnetic ion (Cr (III)) concentration can be rapidly performed by the method.
The design principle of the invention is based on the photocatalytic reduction of heavy metal ions into paramagnetic ions, and the concentration of the paramagnetic ions has an influence on proton relaxation, and T can be measured by low-field nuclear magnetism 2 Numerical quantification of paramagnetic ion concentration effect on proton relaxation, T was established 2 Relationship with paramagnetic ion concentration, finally by T 2 To study the process of photocatalytic reduction of heavy metal ions into paramagnetic ions. On the basis, by means of the in-situ light source equipment, the photocatalysis process can be monitored in real time under the condition that product separation is not needed. According to the invention, the in-situ illumination device can be built only by connecting the optical fiber with the xenon lamp light source through the collecting lens. In situ photocatalysis can be achieved by simply introducing the optical fiber into a low field nuclear magnetic tube containing the reaction mixture to be photocatalysed; by testing the T of protons during illumination 2 The photocatalysis process can be monitored in real time; meanwhile, by utilizing the SE-SPI pulse sequence, the photocatalysis process of the reaction liquid in different space layers can be monitored in real time, and no other technical means can realize similar detection process at present.
Therefore, the equipment provided by the invention is simple and convenient to build, and has simple operation steps and novel technical means. The result obtained by the method is consistent with the trend of the result of the traditional ultraviolet spectrophotometry, but the technical means of the method is simpler.
Compared with the prior art, the invention has the beneficial effects that:
(1) The method can rapidly detect the change of the paramagnetic ion concentration in the solution, does not need to separate products, and has the detection time lower than 1min and far faster than other existing detection means.
(2) The test method is quick and simple, only specific pulse is needed to be applied to the sample, experimental parameters are adjusted, and the system to be tested is not damaged.
(3) The original solution in the system is not required to be subjected to color development treatment, and ions which are not developed can be used for detection.
(4) The in-situ light source device has the advantages of ingenious design, simplicity in operation and low cost, and can detect the photocatalytic heavy metal ion reduction process in real time and evaluate the reduction performance.
(5) The layer selection experiment can observe the reduction state of the photocatalytic heavy metal ions at different spatial layers of the sample in real time, so that the reduction condition of the heavy metal ions at each layer, which are different distances from the light source, in the real solid-liquid reaction environment can be known more deeply.
Drawings
FIG. 1 is a graph showing the attenuation of CMPG at different concentrations of Cr (III) for a single component in example 1 of the present invention;
FIG. 2 is T of the one-component Cr (III) system in example 1 of the present invention 2 A plot of Cr (III) concentration;
FIG. 3 is 1/T of the embodiment 1 of the present invention 2 A graph of Cr (III) ion concentration variation;
FIG. 4 is a graph showing the attenuation of CMPG for different concentrations of Cr (VI) -Cr (III) ions in the blend composition of example 1 of the present invention;
FIG. 5 is T of the mixed component Cr (VI) -Cr (III) system of example 1 of the present invention 2 A plot of Cr (VI) -Cr (III) concentration;
FIG. 6 is 1/T of the embodiment 1 of the present invention 2 A plot of Cr (VI) -Cr (III) ion concentration variation;
FIG. 7 is a schematic diagram showing the overall appearance of in-situ low-field NMR monitoring photocatalytic Cr (VI) reduction in accordance with an embodiment of the invention;
FIG. 8 is the photocatalytic Cr (VI) reduction activity of the photocatalyst measured by ultraviolet spectrophotometry in example 2 of the present invention;
FIG. 9 is a low field nuclear magnetic resonance T of the composite photocatalyst in example 2 of the present invention 2 A graph of change over time of illumination;
FIG. 10 is a schematic view of (a) optional layers and (b) T at different concentrations at different levels in example 3 of the present invention 2 A value;
FIG. 11 is a schematic view of (a) optional layers and (b) T on different layers of the composite photocatalyst in example 3 of the present invention 2 A graph of change with illumination time.
Detailed Description
Preferred embodiments of the present invention will be specifically described below with reference to specific embodiments, but it should be understood that reasonable variations, modifications and combinations of these embodiments can be made by those skilled in the art without departing from the scope of the present invention as defined in the appended claims, thereby obtaining new embodiments, and these new embodiments obtained by variations, modifications and combinations are also included in the scope of protection of the present invention.
The following describes in further detail the embodiments of the present invention by reference to the drawings and examples.
The specific technical proposal for realizing the purpose of the invention is as follows: novel quantitative detection method for heavy metal ion reduction in chemical reaction based on in-situ low-field nuclear magnetic resonance relaxation technology, and paramagnetic ion concentration and proton transverse relaxation rate (1/T) are utilized 2 ) Linear relation between the two, through using CPMG pulse sequence, through the real-time monitoring heavy metal ion reduction in-situ illumination in-process T 2 The change of the (2) can rapidly detect the condition of the increase of the paramagnetic ion concentration, and further characterize the reduction efficiency of heavy metal ions. Meanwhile, the method uses a SE-SPI layer selection sequence to monitor the reduction conditions of heavy metal ions at different layers of the reaction liquid in real time. The method comprises the following specific steps:
(1) Adding the suspension filled with the catalyst powder and the heavy metal ion solution into a matched low-field nuclear magnetic tube, and carrying out ultrasonic homogenization;
(2) The in-situ light source equipment is assembled, a nuclear magnetic tube filled with a sample to be tested is placed in a cavity of a low-field nuclear magnetic resonance spectrometer, and light is introduced into the nuclear magnetic tube through an optical fiber;
(3) System T was performed using the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence 2 Performing in-situ detection on the change condition of the value along with illumination time;
(4) By using Spin Echo-Single Point Imaging (SE-SPI) pulse sequence, T is applied to different layers of a system 2 And (5) detecting the change condition of the value along with illumination time in situ.
In the step (1), the catalyst is 2Ag/g-C 3 N 4 、5Ag/g-C 3 N 4 、Ag 32 NCs/g-C 3 N 4 One or more of, etc.; preferably 5Ag/g-C 3 N 4 、Ag 32 NCs/g-C 3 N 4 。
In the step (1), the addition amount of the catalyst powder is 0.5 mg-10 mg; preferably 5mg.
In the step (1), the heavy metal ion solution is one or more of Cr (VI) solution and the like; preferably a Cr (VI) solution.
In the step (1), the volume of the added heavy metal ion solution is 1-2 mL, and the concentration of the added heavy metal ion solution is 1-20 mg/L.
In the step (1), the diameter of the low-field nuclear magnetic tube is preferably 10mm, and the height is preferably 100mm.
In the step (1), the condition of the ultrasonic is that the ultrasonic power is 40W, the temperature is 20 ℃ and the time is 5min.
The whole in-situ test process does not need to separate products.
In the step (2), the assembling steps of the in-situ light source device are as follows: and connecting the optical fiber bundle consisting of the designed metal-free wrapped bare fibers with a light source through a condensing lens.
The light source is one or more of a common xenon lamp light source, a mercury lamp light source, a metal halogen lamp light source and the like; preferably, the present invention uses a normal 300W xenon lamp as the light source. It is noted that the present invention does not have substantial requirements for light source and illumination intensity.
The invention designs an optical fiber bundle consisting of metal-free wrapped bare fibers, which is mainly used for avoiding interference of a fiber metal wrapping layer on nuclear magnetic signals, ensuring illumination stability and avoiding the situation of no light introduction caused by damage of only a single fiber.
The light source and the nuclear magnetic tube are connected by an optical fiber.
In the step (2), the optical fiber is a custom-made fiber bundle without metal wrapping.
The method can rapidly and quantitatively detect the increase of the paramagnetic ion concentration.
"paramagnetic ion" means specifically that the ion has a strong intrinsic magnetic moment, such as Cr (III), cu (II), etc., as is well known in the art.
In the invention, the system T is prepared by using a Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence 2 The determination of the values is a well-known routine procedure.
In the invention, spin Echo-Single Point Imaging (SE-SPI) pulse sequences are used for T at different layers of a system 2 The determination of the values is a well-known routine procedure.
The height of the light source from the liquid level in all experiments of the invention must be kept consistent, and the height can be adjusted according to requirements. The distance between the light sources is 3cm in the invention.
In one embodiment, the method of the present invention specifically comprises the steps of:
step 1: installation of equipment
And connecting the optical fiber bundle consisting of the designed metal-free wrapped bare fibers with a light source through a condensing lens.
Step 2: sample loading
The test sample was added to a low field nuclear magnetic tube having a diameter of 10mm and a height of 100mm. The low field nuclear magnetic resonance tube is then placed into a low field nuclear magnetic resonance apparatus.
Step 3: the optical fiber is led into the nuclear magnetic tube
The other end of the optical fiber is led into a nuclear magnetic tube placed in a low-field nuclear magnetic field, and the optical fiber is a bare optical fiber bundle. The rest of the wrapped optical fiber (non-bare optical fiber) and the light source device are arranged outside the low-field nuclear magnetic instrument.
In the invention, the single optical fiber and the optical fiber bundle which are led into the low-field nuclear magnetic tube are exposed; the single optical fiber outside the nuclear magnetic tube is exposed, and the optical fiber bundle consisting of the single optical fiber is entirely wrapped by the protective layer.
Step 4: signal acquisition before illumination
And before light is transmitted, carrying out data preliminary acquisition on the sample put into the low-field nuclear magnetic instrument every 5min.
Step 5: signal acquisition in illumination
And (3) turning on a xenon lamp light source, and collecting relaxation data of a sample put into the low-field nuclear magnetic instrument every 5 minutes or 15 minutes.
Step 6: analysis of results
Inversion processing is carried out on the data obtained in the step 4 and the step 5 to obtain T 2 Values. The data inversion process is well known in the art. The results were analyzed by a plotting software and the final results were compared to standard uv spectrophotometry.
Example 1: rapid detection of paramagnetic Cr (III) ions with different concentrations
Step 1: preparation of ion concentration of Cr (III) with different concentrations
One-component Cr (III) system: 1mg/mL of Cr (III) standard solution is diluted to 25mL of Cr (III) solution with different concentrations: 1mg/mL, 5mg/mL, 10mg/mL, 15mg/mL and 20mg/mL.
Mixing components Cr (VI) -Cr (III) system: 1mg/ml Cr (III) standard solution and 100mg/L Cr (VI) solution are prepared into Cr (VI) -Cr (III) mixed solutions with different concentrations: 20-0mg/mL, 15-5mg/mL, 10-10mg/mL, 5-15mg/mL and 0-20mg/mL.
Step 2: low field nuclear magnetic resonance test
1.5ml of the Cr (III) solution with different concentrations in the step 1 is added into a low-field nuclear magnetic tube, and a CPMG sequence is used for testing T 2 Values.
The low-field nuclear magnetic instrument in the step 2 is of the type and specific parameters: a low-field nuclear magnetic analyzer (NMI 20-015V-I) has a magnetic field strength of 0.5 + -0.08T, a proton resonance frequency of 21.3MHz and a probe coil diameter of 15mm. The sampling parameters are as follows: repeated sampling latency (TW) =8000 ms, echo Time (TE) =1 ms, echo Number (NECH) =15000, accumulated Number of Samples (NS) =4.
FIG. 1 is a graph showing the decay of CMPG from 1mg/L to 20mg/L in a single component Cr (III) ion solution. As can be seen from FIG. 1, the signal-to-noise ratio (SNR) of these signals is relatively high at field strength tests around 0.05T, which is advantageous for testing T by fitting 2 . FIG. 2 is a T of a one-component Cr (III) solution 2 Graph of value change. As can be seen from FIG. 2, as the paramagnetic Cr (III) ion concentration in the system increases, T in the system 2 The values show a decreasing trend. This is due to unpaired electrons of the paramagnetic ion in solution and solvent 1 The H nuclei undergo dipole interactions, leading to a faster relaxation of the hydrogen protons. FIG. 3 is 1/T 2 Analysis graph of the change in concentration of Cr (III) ions. As can be seen from FIG. 3, 1/T 2 Exhibits a good linear relationship with the concentration of Cr (III) ions, determines the coefficient (R 2 ) The fit formula is shown in fig. 3 at 0.998.
In order to reflect the changes of Cr (VI) and Cr (III) in the photocatalytic system more truly, the invention has studied the mixed component Cr (VI) -Cr (III) system in the same way as the single component Cr (VI). FIG. 4 is a graph showing the attenuation of CMPG in a mixed component Cr (VI) -Cr (III) system with a concentration gradient of Cr (VI) to Cr (III) of from 20-0mg/L to 0-20 mg/L. As can be seen from FIG. 4, the SNR of the signal in the mixed component Cr (VI) -Cr (III) system is consistent with that of the single component Cr (III), indicating that the system change does not affect the test, and the system T can also be obtained by fitting 2 Is a value of (2). FIG. 5 is a T of a mixed component Cr (VI) -Cr (III) solution 2 Graph of value change. As can be seen from FIG. 5, as the concentration of Cr (VI) ions in the Cr (VI) -Cr (III) system decreases and the concentration of cis-magnetic Cr (III) ions increases, T of the system 2 The values also show a decreasing trend. FIG. 6 is 1/T of the mixed components 2 Analysis graph of the change in concentration of Cr (VI) -Cr (III) ions. As can be seen from FIG. 6, 1/T 2 Exhibits good linear relation with ion concentration of mixed component, R 2 =0.991, the fitting formula is shown in fig. 6. Found by a comparison fitting formula, the single component sumThe formulas obtained by fitting the mixed components are very close, confirming that Cr (VI) will not be T to Cr (III) 2 The test has an impact. Thus T can be used 2 And rapidly judging the paramagnetic Cr (III) ion concentration in the mixed components.
The invention has the advantages of rapidness, real time, low cost and no pretreatment, and well eliminates the interference of other ions.
Referring to FIG. 7, an in-situ low-field NMR measurement method for monitoring the overall appearance of photocatalytic Cr (VI) reduction reaction according to the present invention includes the following steps: firstly, adding a suspension filled with catalyst powder and heavy metal ion solution into a low-field nuclear magnetic tube, then assembling a light source device, placing the nuclear magnetic tube into a cavity of a low-field nuclear magnetic resonance spectrometer, introducing light into the nuclear magnetic tube through an optical fiber, and carrying out in-situ detection on the nuclear magnetic tube. The device can realize real-time monitoring of the reduction process of Cr in the heterogeneous reduction reaction process of photocatalytic Cr (VI) under the reaction condition.
Example 2: in-situ low-field nuclear magnetic resonance real-time detection of Ag/g-C 3 N 4 Photocatalytic Cr (VI) reduction
Step one, preparation of the catalyst
g-C 3 N 4 Is prepared from the following steps: weighing 10g of urea, adding into an alumina crucible, covering the crucible, putting into a muffle furnace, heating to 520 ℃ at a temperature of 5 ℃/min, keeping the temperature for 2 hours, and naturally cooling to room temperature to obtain g-C 3 N 4 And (3) a sample.
Ag/g-C 3 N 4 Is prepared from the following steps: taking 0.2g of the g-C obtained in the above step 3 N 4 Adding into 50mL deionized water, performing ultrasonic dispersion for 1h, adding a certain amount of 1mg/mL silver nitrate solution, magnetically stirring for 0.5h, adding a certain amount of freshly prepared sodium borohydride solution (the mass ratio of Ag to be reduced to sodium borohydride is 1:6), placing into an ice-water bath, stirring for reaction for 1h, performing suction filtration, washing with deionized water for multiple times, and performing vacuum drying at 60 ℃ for 12h. The steps are adopted to prepare light with Ag loading of 1wt%, 2wt%, 5wt% and 10wt% respectivelyCatalytic sample and labeled 1Ag/g-C 3 N 4 、2Ag/g-C 3 N 4 、5Ag/g-C 3 N 4 And 10Ag/g-C 3 N 4 。
Step two, performance characterization test by ultraviolet spectrophotometry
Uniformly dispersing 20mg of catalyst in 50ml of K with concentration of 20mg/L at room temperature 2 Cr 2 O 7 And adding 0.165mL of 100mg/mL citric acid serving as a hole sacrificial agent into the solution, magnetically stirring the mixed solution for 0.5h in the dark, and balancing the adsorption-desorption of the catalyst and the pollutants. The dark-treated solution was placed in a filter with cut-off (lambda)>420 nm) and simulating visible light to perform photocatalysis experiments. During the irradiation of visible light, 1mL of the reaction solution was taken from the reaction tank at given time intervals, filtered through a 0.45 μm polytetrafluoroethylene filter membrane, and the concentration of Cr (VI) was measured by an ultraviolet-visible spectrophotometer at a maximum absorption wavelength of 540nm using a modified Diphenylaminourea (DPC) color development method.
Step three, in-situ low-field nuclear magnetic resonance test
5mg of catalyst and 1.5ml of 20mg/L Cr (VI) solution are added into a nuclear magnetic tube, the nuclear magnetic tube is placed into a low-field nuclear magnetic cavity, one end of an optical fiber is connected to a xenon lamp light source, and the other end of the optical fiber is introduced into the low-field nuclear magnetic tube, so that a test acquisition signal is prepared.
Under the condition of light shielding, carrying out T on the sample in the nuclear magnetic tube at regular intervals 2 And (5) testing. Then a xenon lamp light source is turned on, and in the illumination process, samples in the nuclear magnetic tube are subjected to T at regular intervals 2 And (5) testing.
The low-field nuclear magnetic instrument in the step 3 is of the type and specific parameters: a low-field nuclear magnetic analyzer (NMI 20-015V-I) has a magnetic field strength of 0.5 + -0.08T, a proton resonance frequency of 21.3MHz and a probe coil diameter of 15mm. Selecting a CPMG sequence, wherein sampling parameters are as follows: repeated sampling latency (TW) =8000 ms, echo Time (TE) =1 ms, echo Number (NECH) =15000, accumulated Number of Samples (NS) =4.
FIG. 9 is Ag/g-C 3 N 4 Paramagnetic Cr (III) obtained by reducing Cr (VI) in composite material) T of (2) 2 Graph of the change in value. As shown in FIG. 9, T is in dark condition (i.e., in a period of-5 to 0) 2 The value decreased very slowly over the initial 5min. T due to the rapid increase of paramagnetic Cr (III) ion concentration of the photocatalytic reduction product of Cr (VI) under illumination conditions 2 The value also decreases rapidly. And with the increase of Ag load, ag/g-C 3 N 4 T of composite material 2 The reduction degree is gradually increased, and the order of the reduction degree is 10Ag/g-C in the illumination time of 10min 3 N 4 ≈5Ag/g-C 3 N 4 ＞2Ag/g-C 3 N 4 ＞1Ag/g-C 3 N 4 The performance trend was substantially consistent with the results of the ultraviolet spectrophotometry of FIG. 8. Thus, through T 2 It is possible to evaluate the photocatalytic Cr (VI) reduction activity of the catalyst as a function of the trend of the value with time of illumination.
Example 3: in-situ low-field nuclear magnetic resonance real-time detection of photocatalytic Cr (VI) reduction process at different layers
Step 1: preparation of the catalyst
Preparation of Ag by simple impregnation method 32 NCs/g-C 3 N 4 And (3) a sample. First 0.04g of g-C 3 N 4 Dispersed in 40ml of ethanol solution and sonicated for 1h. Then adding Ag into the mixed solution respectively 32 (MPG) 19 The NCs stock solution was stirred at room temperature for 2h. Finally, obtaining the required nano composite catalyst sample through centrifugation, repeated alcohol washing and vacuum drying.
Step 2: low field nuclear magnetic separation layer experiment
Adding 5mg of catalyst and 1.5ml of 20mg/L Cr (VI) solution into a nuclear magnetic tube, placing the nuclear magnetic tube into a low-field nuclear magnetic cavity, connecting one end of an optical fiber to a xenon lamp light source, introducing the other end into the low-field nuclear magnetic, and testing T at different layers at certain time intervals 2 The conditions of different layers of photocatalytic Cr (VI) reduction are monitored in real time through an in-situ device.
The low-field nuclear magnetic instrument in the step 2 is of the type and specific parameters: a low-field nuclear magnetic analyzer (NMI 20-015V-I) has a magnetic field strength of 0.5 + -0.08T, a proton resonance frequency of 21.3MHz and a probe coil diameter of 15mm. SE-SPI sequence is selected, and sampling parameters are: repeated sampling latency (TW) =8000 ms, echo Time (TE) =0.8 ms, echo Number (NECH) =15000, accumulated sampling Number (NS) =2, number of layers (NTI) =6.
FIG. 10 shows the T on the 1-6 layers of Cr (III) at different concentrations of 5mg/L, 10mg/L and 15mg/L, respectively 2 Is a value of (2). As shown in FIG. 10, when the concentration of Cr (III) ions is 5mg/L, each layer T 2 The values are 610ms. When the concentration of Cr (III) ions is 10mg/L, each layer T 2 The value is 340ms. When the concentration of Cr (III) ions is 15mg/L, all layers T 2 And are 265ms. T for different layers of the same concentration 2 The values remain substantially consistent.
FIG. 11 is Ag 32 NCs/g-C 3 N 4 Process T for Cr (VI) reduction at different levels 2 Relationship to illumination time. T of all layers before illumination 2 The values are the same. With the extension of illumination time, all layers T 2 The values all showed a decreasing trend, since Cr (VI) in the system was reduced to paramagnetic Cr (III). However, since the distances between different layers and the light source are different, the reduction conditions of Cr (VI) at different layers are not consistent, so that the same illumination time is different in different layers T 2 The degree of value reduction is also different. It can be found that at layer 6T nearest to the light source 2 The values are less pronounced and the layer 1, T, furthest from the light source 2 The trend of decrease is slowest. The layer selection experiment can show that the reduction conditions of the photocatalysis Cr (VI) at different layers are different, and the reduction efficiency of the Cr (VI) is higher when the photocatalytic Cr (VI) is closer to the light source.
The invention relates to a new method for detecting heavy metal ion reduction based on in-situ low-field nuclear magnetic resonance technology, namely, paramagnetic ion concentration and proton transverse relaxation rate (1/T) 2 ) Linear relation between the two, through using CPMG pulse sequence, through the real-time monitoring heavy metal ion reduction in-situ illumination in-process T 2 And (3) rapidly detecting the increase of the paramagnetic ion concentration, thereby further representing the reduction efficiency of heavy metal ions. Meanwhile, the method uses a SE-SPI layer selection sequence to monitor the reduction conditions of heavy metal ions at different layers of the reaction liquid in real time. The method has simple operation and no need of pretreatmentThe original solution does not need to separate the product, and has low cost and high accuracy. The method is expected to be popularized in the monitoring aspect of removing other heavy metal ions.
The above-mentioned embodiments are only preferred embodiments of the present invention, and those skilled in the art can make modifications or equivalent substitutions within the spirit of the present invention, such as the reaction involving paramagnetic metal ions in chemical reactions, etc., and all changes made according to the spirit of the present invention shall fall within the scope of the present invention.
Claims (9)
1. A method for detecting heavy metal ions by using in-situ low-field nuclear magnetic resonance relaxation method is characterized in that a linear relation between paramagnetic ion concentration and proton transverse relaxation rate is utilized, and T in the heavy metal ion reduction process is monitored in real time by using CPMG pulse sequences and in-situ illumination 2 The change of the ion concentration of paramagnetic ions is rapidly detected, and the reduction efficiency of heavy metal ions is further represented; simultaneously, a SE-SPI layer selection sequence is used for monitoring the reduction conditions of heavy metal ions at different layers of the reaction liquid in real time;
the specific process is as follows:
(1) Adding the suspension filled with the catalyst powder and the heavy metal ion solution into a matched low-field nuclear magnetic tube, and carrying out ultrasonic homogenization;
(2) The in-situ light source equipment is assembled, a nuclear magnetic tube filled with a sample to be tested is placed in a cavity of a low-field nuclear magnetic resonance spectrometer, and light is introduced into the nuclear magnetic tube through an optical fiber;
(3) System T was performed using the Carr-Purcell-Meiboom-Gill pulse sequence 2 Performing in-situ detection on the change condition of the value along with illumination time;
(4) By using Spin Echo-Single PointImaging pulse sequence, T is applied to different layers of a system 2 And (5) detecting the change condition of the value along with illumination time in situ.
2. The method of claim 1, wherein the heavy metal ion solution is a Cr (VI) solution.
3. The method of claim 1, wherein the catalyst is 2Ag/g-C 3 N 4 、5Ag/g-C 3 N 4 、Ag 32 NCs/g-C 3 N 4 One or more of the following.
4. The method of claim 1, wherein the conditions of the ultrasound are an ultrasound power of 40W, a temperature of 20 ℃ and a time of 5min.
5. The method of claim 1, wherein the catalyst powder is added in an amount of 0.5mg to 10mg, the volume of the solution added with the heavy metal ions is 1mL to 2mL, and the light source and the nuclear magnetic tube are connected by an optical fiber.
6. The method of claim 1, wherein the entire in situ test process does not require product isolation.
7. The method of claim 1, wherein the low field nuclear magnetic tube has a diameter of 10mm and a height of 100mm, and the heavy metal ion solution is added at a concentration of 1mg/L to 20mg/L.
8. The method of claim 1, wherein the optical fiber used is a custom-made metal-free wrapped bundle.
9. The method of claim 1, wherein the data of the sample placed in the low-field nuclear magnetic instrument is initially collected every 5 minutes before the light is transmitted; after the light source is turned on, relaxation data acquisition is carried out on the sample placed in the low-field nuclear magnetic instrument every 5 minutes or 15 minutes.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN200965510Y (en) * | 2006-11-01 | 2007-10-24 | 中国科学院大连化学物理研究所 | A continuous flow hyperpolarization Xe gas generation and sample former position processing device |
| WO2012154555A1 (en) * | 2011-05-06 | 2012-11-15 | The General Hospital Corporation | Nanocompositions for monitoring polymerase chain reaction (pcr) |
| CN107247063A (en) * | 2016-05-13 | 2017-10-13 | 华东理工大学 | A kind of in situ NMR test reactor and detection method |
| CN107817238A (en) * | 2017-12-18 | 2018-03-20 | 兰州大学 | A kind of method that fluorescence based on carbon point recovers screening glutathione reductase inhibitor |
| CN110455848A (en) * | 2018-05-08 | 2019-11-15 | 国家纳米科学中心 | Based on the iron ion longitudinal relaxation time sensor and its construction method of complex reaction amplified signal, purposes |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090088340A1 (en) * | 2007-09-28 | 2009-04-02 | Western Carolina University | Methods for predicting the reduction/oxidation (redox) reaction activity of metal complexes |
| AU2013355183A1 (en) * | 2012-12-07 | 2015-06-11 | T2 Biosystems, Inc. | Methods for monitoring tight clot formation |
| US10994259B2 (en) * | 2018-08-20 | 2021-05-04 | Virginia Tech Intellectual Properties, Inc. | Metal-organic frameworks for the adsorption and catalytic transformations of carbon dioxide |
-
2020
- 2020-05-29 CN CN202010479269.8A patent/CN113740369B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN200965510Y (en) * | 2006-11-01 | 2007-10-24 | 中国科学院大连化学物理研究所 | A continuous flow hyperpolarization Xe gas generation and sample former position processing device |
| WO2012154555A1 (en) * | 2011-05-06 | 2012-11-15 | The General Hospital Corporation | Nanocompositions for monitoring polymerase chain reaction (pcr) |
| CN107247063A (en) * | 2016-05-13 | 2017-10-13 | 华东理工大学 | A kind of in situ NMR test reactor and detection method |
| CN107817238A (en) * | 2017-12-18 | 2018-03-20 | 兰州大学 | A kind of method that fluorescence based on carbon point recovers screening glutathione reductase inhibitor |
| CN110455848A (en) * | 2018-05-08 | 2019-11-15 | 国家纳米科学中心 | Based on the iron ion longitudinal relaxation time sensor and its construction method of complex reaction amplified signal, purposes |
Non-Patent Citations (6)
| Title |
|---|
| Ag改性提高TiO_2对Cr(VI)的光催化还原活性机理;刘守新, 孙承林;物理化学学报(第04期);第355-359页 * |
| Amine functionalized ZIF-8 as a visible-light-driven photocatalyst for Cr(VI) reduction;Chechia Hu等;Journal of Colloid and Interface Science;第372-381页 * |
| Cr(Ⅵ)离子在TiO_2表面的光催化还原机理研究;付宏祥, 吕功煊, 李树本;化学物理学报(第01期);第112-116页 * |
| TiO_2光催化去除废水中重金属离子的研究进展;杨永凡;费学宁;;工业水处理(第07期);第9-13页 * |
| 低场核磁共振技术测定顺磁性钆(Ⅲ)和钕(Ⅲ);胡丽敏;王春宏;田焕娜;王志峰;王津蜀;张明;;分析试验室;第34卷(第12期);第1472-1474页 * |
| 黑暗条件下Cu_2O/Ag_x复合催化还原Cr(Ⅵ)的研究;潘景怡;张嘉;蔡燕洁;李美玲;万霞;铁绍龙;;华南师范大学学报(自然科学版)(第01期);第44-49页 * |
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