Method for detecting contents of various elements in liquid waste

Abstract

The invention discloses a method for detecting contents of various elements in liquid waste. The method comprises a pretreatment process and a formal detection process, the pretreatment process comprises the following steps: S11, selecting a disposable high-purity polyester sample cup without a cup bottom and with a cup cover and activated carbon powder; the sample cup adopts a mylar film to form a cup bottom; s12, firstly weighing the activated carbon powder, putting the activated carbon powder into a beaker, then adding the liquid waste into the beaker, and after the liquid waste infiltrates and adsorbs the activated carbon powder, stirring the liquid waste and the activated carbon powder to be completely and uniformly mixed to form a slurry-shaped test sample; s13, pouring the test sample into a sample cup to form a slurry layer at the inner bottom of the sample cup, covering a cup cover, standing for a period of time, observing whether the Mylar film leaks or not, and performing formal detection after no leakage is confirmed; when the formal detection process is carried out, an X-ray fluorescence spectrophotometer is adopted. The method is easy and convenient to operate, low in cost and suitable for various types of liquid waste.

Description

Technical Field

[0001] The invention relates to a method for detecting the contents of multiple elements in liquid waste. Background Art

[0002] Among the hazardous wastes disposed of by hazardous waste incineration disposal enterprises, the incoming volume of liquid waste can account for up to 50% to 70% of the total disposal volume, and rapid element testing is required before the liquid waste is received to ensure that the content of each element in the liquid waste meets the acceptance requirements for subsequent disposal.

[0003] Due to the constraints of fast acceptance times, wide variability in waste matrix, and the need for a wide measurement range, only X-ray fluorescence spectrometry can currently meet all three of these requirements. The national standard "HJ 1211-2021: Determination of Inorganic Elements in Solid Waste - Wavelength Dispersive X-ray Fluorescence Spectrometry" specifies two solid waste pretreatment methods: the molten glass disc method and the powder pellet method. Furthermore, no relevant literature or standards address liquid waste pretreatment methods.

[0004] However, these two pre-treatment methods have significant limitations: neither is suitable for liquid waste. Direct testing of liquid waste carries a significant risk of leakage, which can impact test accuracy at best and damage testing equipment at worst.

[0005] Therefore, it is an urgent need for hazardous waste incineration and disposal companies to develop a detection method suitable for liquid waste so that liquid waste can meet the detection requirements of X-ray fluorescence spectrometers. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defects of the prior art and provide a method for detecting the content of multiple elements in liquid waste, which is not only simple to operate but also low in cost and can be applied to various types of liquid waste for multiple element detection on an X-ray fluorescence spectrometer.

[0007] The object of the present invention is achieved as follows: a method for detecting the content of multiple elements in liquid waste, including a pre-treatment process and a formal detection process;

[0008] The pre-treatment process includes the following steps:

[0009] S11, selecting a disposable high-purity polyester sample cup without a bottom and with a lid and an inner cover, and activated carbon powder; the sample cup has a Mylar film bottom;

[0010] S12, first weigh activated carbon powder and put it into a beaker, then use a disposable dropper to add liquid waste into the beaker, the mixing mass ratio of activated carbon powder to liquid waste is activated carbon powder: liquid waste = 2:5, after the liquid waste is soaked and adsorbed by the activated carbon powder, use a disposable dropper to stir the liquid waste and activated carbon powder to completely mix them to form a slurry test sample;

[0011] S13, pour the test sample into the sample cup until a mud layer with a thickness greater than 8 mm is formed on the inner bottom of the sample cup. Then, cover the cup and let it stand for a period of time t. Observe the Mylar film at the bottom of the sample cup for leakage. After confirming that there is no leakage, conduct formal testing;

[0012] During the formal testing process, the tester used is an X-ray fluorescence spectrometer; the X-ray radiation source target used by the X-ray fluorescence spectrometer is made of rhodium and can test all elements between carbon and radium in the periodic table except rhodium, helium, neon, argon, krypton, xenon, and radon. During the test, a 10mm collimator and a primary filter are used; the sample chamber is filled with helium with a purity greater than 99.99%, the test temperature is 25°C, and the humidity is 30%;

[0013] The formal testing process includes the following two methods:

[0014] S21, the content of all elements in the test sample except mercury is detected using a standard-free detection method. The standard-free detection method is divided into three channels for detection, namely the titanium-uranium channel, the carbon-scandium channel, and the sulfur-calcium channel in the periodic table. A single sample is scanned for full element coverage under the three channels. The total test time for a single test sample is 300 seconds, of which the total stabilization time is 120 seconds, and the test time for each of the three channels is 60 seconds. The detection voltage of the titanium-uranium channel is 50kV, and the detection current of the titanium-uranium channel is 10-30uA; the detection voltage of the carbon-scandium channel is 15kV, and the detection current of the carbon-scandium channel is 20uA; the detection voltage of the sulfur-calcium channel is 15kV, and the detection current of the sulfur-calcium channel is 200-600uA.

[0015] S22. The mercury content in the test sample is detected using a standard sample detection method. First, several standard solutions with Hg mercury content are used to prepare standard samples, or several standard samples with known mercury content are directly used to perform signal intensity tests on an X-ray fluorescence spectrometer. A standard curve is then established between the mercury content in the standard sample and the signal intensity of the X-ray fluorescence spectrometer. Then, a test sample with an unknown mercury content is tested to obtain the corresponding signal intensity value of the X-ray fluorescence spectrometer. The mercury content in the test sample is then determined using the standard curve. This standard sample detection method only performs a single scan on the mercury element, with a detection time of 100 s, a detection voltage of 50 kV, and a detection current of 100 uA.

[0016] During the formal test, place the sample cup with the test sample into the sample chamber of the X-ray fluorescence spectrometer and close the cover; select the corresponding test method in the analysis software of the X-ray fluorescence spectrometer, enter the name of the test sample, and start the test after confirming that the test conditions are correct; after the test is completed, remove the test sample from the sample chamber in time.

[0017] In the above method for detecting the content of multiple elements in liquid waste, when performing step S11, the activated carbon powder is wood activated carbon powder or cyclodextrin.

[0018] In the above-mentioned method for detecting the content of multiple elements in liquid waste, two ventilation holes are provided on the cover of the sample cup.

[0019] In the above method for detecting the content of multiple elements in liquid waste, when performing step S13, the standing period t is at least 15 minutes.

[0020] The method for detecting the contents of multiple elements in liquid waste of the present invention has the following characteristics:

[0021] 1. The pre-treatment process is easy to operate and takes less time. The entire pre-treatment process only takes about 2 minutes.

[0022] 2. Low cost, only low-cost consumables such as activated carbon powder, disposable plastic cups, disposable droppers and a small amount of Mylar film are required.

[0023] 3. It is widely applicable to various types of liquid waste for multiple element detection on X-ray fluorescence spectrometer, including organic, inorganic, acidic and alkaline liquid waste. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the embodiments.

[0025] The method for detecting the content of multiple elements in liquid waste of the present invention includes a pre-treatment process and a formal detection process;

[0026] The pre-processing process includes the following steps:

[0027] S11: Use a disposable high-purity polyester sample cup without a bottom but with a lid and inner cover, and activated carbon powder. The activated carbon powder should be wood-based activated carbon powder with a particle size of 200 mesh or cyclodextrin. The bottom of the sample cup should be formed by tightening a 6μm thick Mylar film by buckling it onto the inner cover of the sample cup. The lid of the sample cup has two vents. During the test, the volatilized sample can escape through the vents, effectively preventing the Mylar film from expanding and rupturing due to excessive pressure inside the sample cup. The Mylar film at the bottom of the sample cup must be flat and free of foreign matter, otherwise it will affect the test results.

[0028] S12, first weigh 4g of activated carbon powder and put it into a beaker, then use a disposable dropper to add 10g of liquid waste to the beaker, the mixing mass ratio of activated carbon powder to liquid waste is activated carbon powder: liquid waste = 2:5. After the liquid waste is soaked and adsorbed by the activated carbon powder, use a disposable dropper to stir the liquid waste and activated carbon powder to completely mix them to form a slurry test sample of 15 ml;

[0029] S13: Pour the test sample into the sample cup until a slurry layer greater than 8 mm thick forms at the bottom of the inner cavity of the sample cup. Cover the cup and let it sit for at least 15 minutes. Observe the Mylar film at the bottom of the sample cup for any leakage. After confirming that there is no leakage, proceed to the formal test.

[0030] When conducting the formal testing process, the tester used is an X-ray fluorescence spectrometer (manufactured by Shimadzu Instruments). The X-ray radiation source target used by the X-ray fluorescence spectrometer is made of Rh rhodium and can test all elements in the periodic table from C carbon to U radium, except for Rh rhodium, He helium, Ne neon, Ar argon, Kr krypton, Xe xenon, and Rn radon. A 10mm collimator and a primary filter are used during the test. The sample chamber is filled with helium with a purity greater than 99.99%. The test temperature is 25°C and the humidity is 30%.

[0031] The formal testing process includes the following two methods:

[0032] S21, the detection of the content of other elements in the test sample except mercury Hg adopts the standard-free detection method, which is divided into three channels for detection. The three channels are the Ti titanium-U uranium channel, the C carbon-Sc scandium channel and the S sulfur-Ca calcium channel in the periodic table; a single sample is scanned for full element coverage under the three channels; the total test time for a single test sample is 300s, of which the total stabilization time is 120s, and the test time of the three channels is 60s respectively; the detection voltage of the Ti titanium-U uranium channel is 50kV, and the detection current of the Ti titanium-U uranium channel is 10-30uA; the detection voltage of the C carbon-Sc scandium channel is 15kV, and the detection current of the C carbon-Sc scandium channel is 20uA; the detection voltage of the S sulfur-Ca calcium channel is 15kV, and the detection current of the S sulfur-Ca calcium channel is 200-600uA;

[0033] S22. The Hg content in the test sample is detected using a standard sample detection method. First, standard samples are prepared using several standard solutions with different Hg content, or several standard samples with known Hg content are directly used to perform signal intensity tests on an X-ray fluorescence spectrometer. A standard curve is then established between the Hg content in the standard sample and the signal intensity of the X-ray fluorescence spectrometer. Then, a test sample with an unknown Hg content is tested to obtain the corresponding X-ray fluorescence spectrometer signal intensity value. The Hg content in the test sample is then obtained using the standard curve. This standard sample detection method only performs a single scan on the Hg element, with a detection time of 100 s, a detection voltage of 50 kV, and a detection current of 100 uA.

[0034] During the formal test, place the sample cup with the test sample into the sample chamber of the X-ray fluorescence spectrometer and close the cover; select the corresponding test method in the analysis software of the X-ray fluorescence spectrometer, enter the name of the test sample, and start the test after confirming that the test conditions are correct; after the test is completed, remove the test sample from the sample chamber in time.

[0035] Since there are many unknown elements in liquid waste, some elements will interfere with each other. It is necessary to combine the detection peak image of the X-ray fluorescence spectrometer or the data of other analytical experiments, and correct the detection results in the analysis software of the measuring instrument to obtain more accurate experimental results.

[0036] The test samples were tested seven times, and seven blank tests were performed. The accuracy and detection limit were calculated according to the National Environmental Protection Standard of the People's Republic of China HJ 168-2010 "Technical Guidelines for the Development and Revision of Environmental Testing and Analytical Methods". The calculation results are shown in the table below:

[0037]

[0038]

[0039] It can be seen from the data in the above table that at the level of 100 mg / L, after pre-treatment with activated carbon, the test results are still quite reliable and sufficient to guide the subsequent disposal of liquid waste.

[0040] Since liquid waste is directly added to the sample cup, leakage is very likely to occur. If liquid waste leaks into the X-ray fluorescence emission window below the sample chamber, it can damage the X-ray fluorescence spectrometer. The present invention adds activated carbon powder to the liquid waste, forming a slurry test sample. This slurry test sample can remain stable on the Mylar film for more than 30 minutes, making the X-ray fluorescence spectrometer suitable for liquid waste detection.

[0041] The method for detecting the content of multiple elements in liquid waste of the present invention is simple to operate, and the manual time of the pre-treatment process only takes about 2 minutes;

[0042] The method for detecting the contents of multiple elements in liquid waste of the present invention has low cost and only requires low-cost consumables, namely, activated carbon, a disposable plastic cup, a disposable dropper and a small amount of Mylar film.

[0043] The method for detecting the content of multiple elements in liquid waste of the present invention is widely applicable to performing multiple element detection on various types of liquid waste on an X-ray fluorescence spectrometer, including organic, inorganic, acidic and alkaline liquid waste.

[0044] The above embodiments are only used to illustrate the present invention, rather than to limit the present invention. Those skilled in the art may make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also fall within the scope of the present invention and should be defined by the claims.

Claims

1. A method for detecting the content of multiple elements in liquid waste, characterized in that: The detection method includes a pre-processing process and a formal detection process; The pre-treatment process includes the following steps: S11, selecting a disposable high-purity polyester sample cup without a bottom and with a lid and an inner cover, and activated carbon powder; the sample cup has a Mylar film bottom; S12, first weigh activated carbon powder and put it into a beaker, then use a disposable dropper to add liquid waste into the beaker, the mixing mass ratio of activated carbon powder to liquid waste is activated carbon powder: liquid waste = 2:5, after the liquid waste is soaked and adsorbed by the activated carbon powder, use a disposable dropper to stir the liquid waste and activated carbon powder to completely mix them to form a slurry test sample; S13, pour the test sample into the sample cup until a mud layer with a thickness greater than 8 mm is formed on the inner bottom of the sample cup. Then, cover the cup and let it stand for a period of time t. Observe the Mylar film at the bottom of the sample cup for leakage. After confirming that there is no leakage, conduct formal testing; During the formal testing process, the tester used is an X-ray fluorescence spectrometer; the X-ray radiation source target used by the X-ray fluorescence spectrometer is made of rhodium and can test all elements between carbon and radium in the periodic table except rhodium, helium, neon, argon, krypton, xenon, and radon. During the test, a 10mm collimator and a primary filter are used; the sample chamber is filled with helium with a purity greater than 99.99%, the test temperature is 25°C, and the humidity is 30%; The formal testing process includes the following two methods: S21, the content of all elements in the test sample except mercury is detected using a standard-free detection method. The standard-free detection method is divided into three channels for detection, namely the titanium-uranium channel, the carbon-scandium channel, and the sulfur-calcium channel in the periodic table. A single sample is scanned for full element coverage under the three channels. The total test time for a single test sample is 300 seconds, of which the total stabilization time is 120 seconds, and the test time for each of the three channels is 60 seconds. The detection voltage of the titanium-uranium channel is 50kV, and the detection current of the titanium-uranium channel is 10-30uA; the detection voltage of the carbon-scandium channel is 15kV, and the detection current of the carbon-scandium channel is 20uA; the detection voltage of the sulfur-calcium channel is 15kV, and the detection current of the sulfur-calcium channel is 200-600uA. S22. The mercury content in the test sample is detected using a standard sample detection method. First, several standard solutions with Hg mercury content are used to prepare standard samples, or several standard samples with known mercury content are directly used to perform signal intensity tests on an X-ray fluorescence spectrometer. A standard curve is then established between the mercury content in the standard sample and the signal intensity of the X-ray fluorescence spectrometer. Then, a test sample with an unknown mercury content is tested to obtain the corresponding signal intensity value of the X-ray fluorescence spectrometer. The mercury content in the test sample is then determined using the standard curve. This standard sample detection method only performs a single scan on the mercury element, with a detection time of 100 s, a detection voltage of 50 kV, and a detection current of 100 uA. During the formal test, place the sample cup with the test sample into the sample chamber of the X-ray fluorescence spectrometer and close the cover; select the corresponding test method in the analysis software of the X-ray fluorescence spectrometer, enter the name of the test sample, and start the test after confirming that the test conditions are correct; after the test is completed, remove the test sample from the sample chamber in time.

2. The method for detecting the content of multiple elements in liquid waste according to claim 1, characterized in that: When performing step S11, the activated carbon powder is wood activated carbon powder or cyclodextrin.

3. The method for detecting the content of multiple elements in liquid waste according to claim 1, characterized in that: Two vent holes are provided on the cup cover of the sample cup.

4. The method for detecting the content of multiple elements in liquid waste according to claim 1, characterized in that: When performing step S13, the standing period t is at least 15 minutes.

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