CN111088501B - Recovery and reuse method of element analyzer reduction tube - Google Patents
Recovery and reuse method of element analyzer reduction tube Download PDFInfo
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- CN111088501B CN111088501B CN201911292316.1A CN201911292316A CN111088501B CN 111088501 B CN111088501 B CN 111088501B CN 201911292316 A CN201911292316 A CN 201911292316A CN 111088501 B CN111088501 B CN 111088501B
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
- C23G1/10—Other heavy metals
- C23G1/103—Other heavy metals copper or alloys of copper
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G3/00—Apparatus for cleaning or pickling metallic material
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/12—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using combustion
Abstract
The invention relates to the field of elemental analysis, and discloses a recovery and reuse method of a reduction tube of an elemental analyzer. The method has the advantages of low cost, simple operation, no need of other large instruments, high popularity and effective reduction of the running cost of the instruments. The specific surface area of the linear copper recovered by the method is much larger than that of the new linear copper, the reduction capability is enhanced, and the measurement result of the nitrogen element is more accurate when measuring samples containing high nitrogen content such as nitro, nitrogen-containing heterocycle and the like.
Description
Technical Field
The invention relates to the field of elemental analysis, in particular to a recovery and reuse method of a reduction tube of an elemental analyzer.
Background
The element analysis is an important quantitative analysis method, and is often used as an important supplement to qualitative analysis methods such as nuclear magnetism, mass spectrum, chromatogram and the like, and provides element composition and content information of a tested sample. Therefore, the elemental analyzer has been widely used in various fields such as chemistry, chemical engineering, pharmacy, materials, energy, food, environment, agriculture, and the like. At present, a plurality of important academic journals take element analysis data as important indexes for explaining purity, and the important academic journals are required to be provided.
The working principle of the element analyzer CHN mode is as follows: in the combustion tube, the sample is burnt and decomposed under the action of high temperature, oxygen enrichment and catalyst to be converted into CO2、H2O、NOXThe mixed gas of (3); the mixed gas enters a reduction tube under the push of carrier gas, and NO is converted by the reducing agent wire-shaped copper particlesXReduction to N2While absorbing excess O2(ii) a Then, N2、CO2、H2The O is carried out of the reduction tube by the carrier gas and enters an adsorption-desorption column, and gas components are separated through adsorption-desorption; and the separated gas sequentially enters a thermal conductivity detector for detection, and the computer respectively calculates the percentage content of each element in the sample according to the signal value of each component and the correction curve of the corresponding element.
At present, the element analyzer has two problems: firstly, the reducing agent linear copper is fast in consumption and large in consumption, black copper oxide generated after oxidation is sintered to form a copper oxide column, and the copper oxide column is difficult to take out of a quartz tube, so that the reducing tube is scrapped integrally, and the running cost of an instrument is very high; secondly, under the condition of rapid dynamic combustion, a high-nitrogen-content sample with structures of nitrogen-containing heterocycles, nitryl and the like has a low nitrogen analysis result. Therefore, it is of great significance to research how to reduce the running cost of the instrument and how to improve the reduction capability of the reduction tube under the condition of rapid dynamic combustion so as to improve the accuracy of the nitrogen element determination result.
CN106001597A discloses a method for recovering copper columns in an element analyzer, which is to reduce oxidized copper columns in the element analyzer by low-temperature plasma; then, carrying out high-temperature annealing on the reduced copper column to obtain a nano copper oxide wire array in an emission structure; and reducing the nano copper oxide wire on the copper column into a nano copper wire under the action of low-temperature plasma. The method utilizes the plasma reduction and high-temperature annealing method, can reduce the used copper column, and realizes the recovery of the copper column.
CN 103146931a discloses a copper oxide reduction apparatus and method, the apparatus comprising: the box-type electric heating furnace comprises a box-type electric heating furnace, a quartz tube, an inner nut sealing element and an outer nut sealing element matched with the inner nut sealing element; filling quantitative copper oxide into a quartz tube, respectively sleeving an inner nut sealing element and an outer nut sealing element on two ends of the quartz tube to realize sealing, and placing the quartz tube in a groove of a box type electric heating furnace; after hydrogen is input for a period of time through the air inlet on the outer nut sealing element, the box type electric heating furnace is started; the box-type electric heating furnace is continuously heated, and the heating is stopped after the copper oxide in the quartz tube becomes golden; and stopping hydrogen input after the temperature of the quartz tube is reduced to the room temperature. The method can solve the problem that the existing method occupies the element analyzer when granular copper in the element analyzer is reduced, and influences the normal use of the element analyzer.
However, the regeneration method of the reduction tube in several element analyzers disclosed in the prior art is complicated in process, needs other large-scale instruments, is low in method popularity and high in recovery cost, and is against the original purpose of recovery. Therefore, the recovery and utilization method of the reduction tube of the element analyzer, which is safe, reliable, simple to operate and low in cost, is urgently needed.
Disclosure of Invention
The invention aims to provide a method for recovering an element analysis reduction tube, which has low cost and simple operation, can obtain a clean quartz tube and can also recover linear copper, the recovery rate of the linear copper can reach 47.88 percent at most, does not need to depend on other large-scale instruments, has high popularity and can effectively reduce the running cost of the instruments.
In order to achieve the purpose, the invention adopts the technical scheme that:
a recovery method of a reduction tube of an elemental analyzer, wherein the reduction tube is a quartz tube filled with failure linear copper, comprises the following steps:
(1) leaching the reduction tube by dilute sulphuric acid until the failure linear copper can be separated from the quartz tube;
(2) pouring out the failed linear copper from the quartz tube, and cleaning and drying the quartz tube to obtain a clean quartz tube;
(3) and soaking the ineffective linear copper in the dilute sulfuric acid for 3-10h, then taking out, washing, drying, sieving and recovering to obtain the linear copper.
The failed linear copper means that after the element analyzer operates for many times, the surface of the linear copper of the reducing agent is oxidized to generate black copper oxide, and finally the reduction capability is lost. Meanwhile, black copper oxide is sintered to form a copper column which is difficult to take out of the quartz tube, so that the reduction tube is scrapped integrally, wherein the sintered copper column is called as failure linear copper.
The invention utilizes the simplest chemical principle, dilute sulphuric acid reacts with copper oxide on the surface of the failed linear copper, the linear copper is easily dropped from the quartz tube and poured out, then the quartz tube is washed by alkaline water and washed by pure water for a plurality of times, and the clean quartz tube is obtained after drying.
Continuously soaking the fallen and poured ineffective linear copper by using dilute sulfuric acid to ensure that the copper oxide on the surface of the ineffective linear copper continuously reacts with the dilute sulfuric acid to expose pure copper which is not oxidized inside, wherein the soaking time is 3-10 hours to ensure that the copper oxide is completely reacted; and taking out the soaked linear copper, washing the linear copper for multiple times by using pure water, drying and recovering to obtain the reusable linear copper. The failure wire form copper should contain pure copper that is not oxidized.
The concentration of the dilute sulfuric acid is 2.3-9.2 mol/L. The concentration of dilute sulfuric acid is not desirable to be too high, since concentrated sulfuric acid does not react with copper oxide and reacts with pure copper.
The leaching time of the reduction tube in the step (1) is 20-60min, and when the concentration of the dilute sulfuric acid is lower, the leaching time can be properly prolonged, or the dilute sulfuric acid is heated and leached while the dilute sulfuric acid is hot.
Preferably, the concentration of the dilute sulfuric acid is 2.6-6.1mol/L, the leaching time of the reduction tube in the step (1) is 20-40min, and the soaking time of the failed linear copper in the step (3) is 4-8 h.
Further preferably, the concentration of the dilute sulfuric acid is 3.1-4.6mol/L, the leaching time of the reduction tube in the step (1) is 20-30min, and the soaking time of the failed linear copper in the step (3) is 4-6 h. Under the condition, the recovery rate of the linear copper is high, the consumed time is appropriate, and the recovery rate of the linear copper can reach more than 30 percent.
The method can not only obtain a clean quartz tube, but also recover unreacted linear copper, and the inventor unexpectedly finds that the linear copper recovered by the method has rough surface, greatly increased specific surface area and enhanced reduction capability for reuse.
The drying in the step (3) is carried out for 0.5 to 3 hours at the temperature of between 60 and 80 ℃ under the vacuum condition. The recovered linear copper has many surface defects or grooves, and it is necessary to sufficiently dry the copper to completely remove the water on the surface.
The invention also aims to provide a method for improving the accuracy of the nitrogen element measurement result of the element analyzer, and in order to realize the aim, the technical scheme adopted by the invention is as follows:
the wire-shaped copper recovered by the above method was used in an elemental analyzer for measuring nitrogen-containing compounds. The method comprises the specific steps of filling the recycled linear copper in a quartz tube, and assembling the linear copper on an element analyzer for measuring compounds with high nitrogen content.
Tests show that the specific surface area of the linear copper obtained by recovery is greatly increased, the reduction capability is enhanced, and the accuracy of the measurement result of the nitrogen element is higher when samples containing high nitrogen content such as nitro, nitrogen-containing heterocycle and the like are measured.
The wire-shaped copper can be used after being screened, and the mesh number of the used screen is 70-100 meshes. Some of the agglomerated wire-like copper with too large particles was screened off.
Compared with the prior art, the invention has the following beneficial effects:
(1) compared with the existing treatment method, the recovery method of the reduction tube has the advantages of simple operation, low cost, safety, reliability and strong universality.
(2) The specific surface area of the linear copper obtained by the recovery method of the reducing tube is far larger than that of the commercial linear copper, which is beneficial to the reduction reaction, the reducing capability of the reducing tube is improved under the condition of rapid dynamic combustion, and the accuracy of the nitrogen element measurement result is improved.
(3) The invention effectively reduces the running cost of the instrument, improves the accuracy of the nitrogen element measurement result of the element analyzer by utilizing the recycled linear copper, provides a new idea for further development of the field of element analysis, and fully embodies the remarkable effect of the invention.
Drawings
FIG. 1 (a) is a scanning electron micrograph of a whole new copper wire at 400 times magnification; (b) a scanning electron microscope image of brand new linear copper magnified 2000 times; (c) a scanning electron micrograph of the recovered copper wire of example 1 magnified 400 times; (d) is a scanning electron micrograph of the collected copper wire of example 1, magnified 2000 times.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Those skilled in the art should understand that they can make modifications and equivalents without departing from the spirit and scope of the present invention, and all such modifications and equivalents are intended to be included within the scope of the present invention.
The elemental analyzer used in the following embodiment is a vario MICRO cube of the firm elementar, Germany. The standard sample acetanilide is purchased from sigma company, and the metronidazole standard is purchased from Nantong Feiyu Biotechnology Limited.
Example 1
Placing a failed reducing tube in a 500mL plastic measuring cylinder, slowly leaching the reducing tube by using 3.1mol/L dilute sulfuric acid, continuously leaching until the failed linear copper can be separated from the quartz tube, wherein the leaching time is about 30 min;
pouring the ineffective linear copper out of the quartz tube, brushing the quartz tube with alkali water, and washing the quartz tube with pure water for multiple times to obtain a clean quartz tube;
after the invalid linear copper is soaked in dilute sulfuric acid for 6 hours, fully reacting sintered copper oxide, taking out unreacted pure copper, washing the pure copper for multiple times by water, drying the pure copper for 1 hour at the temperature of 80 ℃ in vacuum, and recovering the linear copper, wherein the recovery rate of the linear copper in multiple tests is (47.88 +/-2.78)%.
When the surfaces of the virgin wire-like copper and the recovered wire-like copper were observed by a scanning electron microscope, as shown in FIG. 1, (a) and (b) in FIG. 1 show that the virgin wire-like copper had a smooth and flat surface, and (c) and (d) in FIG. 1 show that the recovered wire-like copper had a rough surface, many fine depressions, and an increased specific surface area.
And (3) recycling the recovery reduction pipe:
the recovered wire-like copper was filled in a quartz tube to obtain a recovered reduction tube and assembled into an elemental analyzer, and the instrument was opened and the temperatures of the reduction tube, the combustion tube and the detector were raised to 650 ℃, 950 ℃ and 59.7 ℃, respectively. A blank was then run and the blank peak area of the element of instrument C, H, N, i.e., the instrument background, was examined. The standard acetanilide was run and the accuracy and precision of the standard and the daily correction factor for element C, H, N were examined. The conclusion is drawn after the experiment: the instrument is provided with a recovered reduction tube, and the C, N background reaches the standard after running for 3 times and blank, which is basically consistent with the current situation of purchase; the H element background can reach the standard after the instrument runs for more than 16 times; the results of the runs for the standard acetanilide are shown in Table 1, and the daily correction factors for the C, H, N elements are 1.0060, 1.0209 and 1.0165, respectively, indicating that the instrument performance is excellent using the recovered reducing tube.
TABLE 1 measurement of acetanilide element content by recovery of reduction tube
| Item | C(w％) | H(w％) | N(w％) |
| First measurement | 70.65 | 6.49 | 10.21 |
| Second measurement | 70.68 | 6.62 | 10.17 |
| Third measurement | 70.68 | 6.61 | 10.20 |
| Theoretical value | 71.09 | 6.71 | 10.36 |
| Daily correction factor | 1.0060 | 1.0209 | 1.0165 |
Example 2
After the recovery reduction tube prepared in example 1 was assembled in an instrument, the instrument was heated, a blank sample and a standard sample were removed, and the content of metronidazole element was measured, and the test results are shown in table 2.
TABLE 2 measurement of Metronidazole element content by recovery of reduction tube
| Item | C(w％) | H(w％) | N(w％) |
| First measurement | 42.00 | 5.36 | 24.56 |
| Second measurement | 42.01 | 5.32 | 24.55 |
| Third measurement | 41.96 | 5.34 | 24.58 |
| Theoretical value | 42.07 | 5.26 | 24.54 |
Comparative example 1
The reduction tube filled with the brand new linear copper is assembled into an instrument, the instrument is heated, a blank sample and a standard sample are moved, the content of the metronidazole element is measured, and the test results are shown in table 3.
TABLE 3 measurement results of Metronidazole element content using the completely new line copper
| Item | C(w％) | H(w％) | N(w％) |
| First measurement | 41.96 | 5.35 | 24.24 |
| Second measurement | 41.96 | 5.35 | 24.30 |
| Third measurement | 42.00 | 5.37 | 24.30 |
| Theoretical value | 42.07 | 5.26 | 24.54 |
As can be seen from the test results in Table 2, the deviation of the measured value from the theoretical value of the linear copper recovered by the method of the invention for measuring the content of C, H, N element in metronidazole is within 0.11%, which shows that the accuracy and precision of the recovered linear copper reutilizing instrument are high.
As can be seen from comparison of tables 2 and 3, the accuracy of the result of the N content in metronidazole determined by utilizing the recycled linear copper is higher than that determined by utilizing brand new linear copper, and the linear copper recovered by the method provided by the invention has enhanced reducing capability, and the determination result of nitrogen element is more accurate when a compound with high nitrogen content is determined.
Claims (3)
1. A method for improving the accuracy of the measurement result of nitrogen element of an element analyzer is characterized in that the linear copper obtained by the recovery method of a reduction tube of the element analyzer is used for measuring nitrogen-containing compounds in the element analyzer,
the reduction tube is a quartz tube filled with failure linear copper, so the recovery method comprises the following steps:
(1) leaching the reduction tube by dilute sulphuric acid until the failure linear copper can be separated from the quartz tube;
(2) pouring out the failed linear copper from the quartz tube, and cleaning and drying the quartz tube to obtain a clean quartz tube;
(3) soaking the failed linear copper in the dilute sulfuric acid for 6 hours, then taking out, washing, drying and recovering to obtain linear copper;
the concentration of the dilute sulfuric acid is 3.1mol/L, and the leaching time of the reduction tube in the step (1) is 30 min.
2. The method for improving the accuracy of the measurement result of the nitrogen element in the element analyzer according to claim 1, wherein the drying in the step (3) is a treatment at 60-80 ℃ for 0.5-3h under vacuum.
3. The method of improving the accuracy of elemental analyzer nitrogen measurements of claim 1 wherein the copper wire is screened with a 70-100 mesh screen prior to use.
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| JP5381475B2 (en) * | 2009-08-06 | 2014-01-08 | 株式会社Ｓｕｍｃｏ | Method for reclaiming recovered polycrystalline silicon |
| CN106001597B (en) * | 2016-07-08 | 2018-03-20 | 武汉工程大学 | The recovery method of copper post in a kind of elemental analyser |
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