Method for detecting total sulfur in waste

Abstract

The invention discloses a method for detecting total sulfur in waste, which is characterized in that on the basis of the original oxygen bomb combustion method-ion chromatography detection, treatment including pH regulation and oxidation treatment is added for the obtained absorption liquid, and sulfite radicals in the absorption liquid can be completely oxidized into sulfate radicals as far as possible; therefore, the stability and the accuracy of a subsequent ion chromatography detection result are ensured.

Description

Technical Field

[0001] The invention belongs to the field of applied analysis technology, and in particular relates to a method for detecting total sulfur in waste. Background Art

[0002] One of the main sources of air pollutants is solid waste. In fact, there are many ways in which solid waste pollutes the atmosphere, the typical ones include:

[0003] (1) Fine particles of waste are blown up by the wind, increasing the dust content in the atmosphere and aggravating dust pollution in the atmosphere;

[0004] (2) Due to the low dust removal efficiency during the production process, a large amount of dust is directly discharged into the atmosphere, polluting the atmosphere;

[0005] (3) Harmful components in the stored solid waste produce toxic gases due to volatilization and chemical reactions, leading to air pollution.

[0006] Moreover, the open-air storage of solid waste not only occupies a large amount of land, but the toxic and harmful components it contains will also seep into water bodies and soil, making the water and soil alkaline, acidic, and poisonous, destroying the living conditions of organisms.

[0007] Based on the above hazards of solid waste, and the fact that a large amount of solid waste is produced in the daily production of enterprises, enterprises have gradually adhered to the principles of reduction, resource utilization and harmlessness in the prevention and control of solid waste pollution, and clarified the principle of polluter pays in terms of system. The premise for achieving the above purpose is to be able to effectively and accurately detect the solid waste. Among them, the total sulfur content is one of the important items for solid waste detection, and the sulfur will generate sulfur dioxide during the high-temperature incineration of waste, and sulfur dioxide is one of the main pollutants in the atmosphere. Therefore, during the high-temperature incineration of waste, the accuracy of the determination of the total sulfur content in the waste is increasingly required.

[0008] At present, the main method for determining the total sulfur content in waste in the laboratory is oxygen bomb combustion-ion chromatography. This method puts the weighed sample into an oxygen bomb, adds an appropriate amount of absorption liquid (water or alkali solution) into the oxygen bomb, and then fills a certain amount of oxygen into the oxygen bomb to ensure that the sample is fully burned in the oxygen bomb, so that the sulfur element in the sample is converted into SO3 (there is also a certain amount of SO2), and then further reacts with the absorption liquid to generate sulfate and sulfite to obtain a test solution, and then uses an ion chromatography column to perform ion chromatography analysis on the test solution, and calculates the total sulfur content in the sample based on the peak values ​​of sulfate and sulfite.

[0009] Based on the above, it is not difficult to see that ensuring that the sample is fully burned and oxidized in the oxygen bomb is an important factor affecting the accuracy of the test. For example, Patent Document 1 provides a method for determining the halogen and sulfur content in industrial solid waste by oxygen bomb combustion method. By adding a certain amount of H2O2, it can promote the oxidation of sulfur during the combustion process, ensure that the sulfur is burned as completely as possible during the determination process, reduce losses, and ensure the accuracy of the test results; for example, Patent Document 2 provides a method for detecting the halogen and sulfur content in hazardous waste samples. It also adds a certain amount of H2O2 to the oxygen bomb to ensure that the sulfur is burned as completely as possible during the determination process, reduce losses, and ensure the accuracy of the test results.

[0010] In addition, the ion chromatography column is another important factor related to the accuracy of the test. When the column efficiency of the ion chromatography column decreases, the analysis error will be large. Therefore, in practice, in order to ensure the accuracy of the test, the ion chromatography column needs to be replaced more frequently, resulting in increased testing costs. Based on this, in Patent Document 1, an SPE column is installed in front of the ion chromatography injection port to prevent the interference of alkaline metal ions and transition metal ions on the test results, which is beneficial to improve the measurement accuracy; for example, in Patent Document 2, before the test, the pH of the test solution is adjusted to 8.2-9.0 to avoid damage to the ion chromatography column by the sample, avoid interference of multiple ions on the detection baseline, and improve the detection limit of the detection method.

[0011] Patent document 1: Application number 201610473394.1, method for determining halogen and sulfur content in industrial solid waste by oxygen bomb combustion method;

[0012] Patent document 2: Application number is 201910412957.X, a method for detecting halogen and sulfur content in hazardous waste samples. Summary of the invention

[0013] 1. Problem to be solved

[0014] One of the purposes of the present invention is to provide a method for detecting total sulfur in waste, which can effectively ensure the accuracy of the determination of the total sulfur content in the waste.

[0015] 2. Technical solution

[0016] In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0017] According to the purpose of the present invention, the method for detecting total sulfur in waste provided by the present invention comprises the following steps:

[0018] S1 uses an oxygen bomb combustion method to treat the waste to obtain a test liquid containing sulfur element;

[0019] Wherein, the sulfur element is derived from the waste;

[0020] S2 adjusting the pH value of the test solution to 2.8-4.0;

[0021] S3 performs oxidation treatment on the liquid to be tested;

[0022] S4 uses ion chromatography to detect the sulfur content in the test solution.

[0023] According to any embodiment of the first aspect of the present invention, in S2, the pH value of the test solution is adjusted to 2.8-3.0.

[0024] According to any embodiment of the first aspect of the present invention, in S2, pH value is adjusted by using acid solution;

[0025] The acid does not contain elemental sulfur and does not react with the elemental sulfur to form a precipitate.

[0026] According to any embodiment of the first aspect of the present invention, in S2, pH value is adjusted by using acid solution;

[0027] The acid comprises any one, two or three of hydrochloric acid, nitric acid and phosphoric acid;

[0028] If the acid includes any two or three of hydrochloric acid, nitric acid and phosphoric acid at the same time, the various acids can be mixed in any proportion.

[0029] According to any embodiment of the first aspect of the present invention, in S2, nitric acid is preferably used to adjust the pH value. The reasons are: (1) nitric acid has strong oxidizing properties, which can save the amount of subsequent oxidants; (2) nitric acid has strong acidity, which can reduce the amount of acid used; (3) the separation between the peak position of nitric acid and the peak position of sulfate ion on the ion chromatogram is greater.

[0030] According to any embodiment of the first aspect of the present invention, in S3, the test liquid is oxidized using a sulfur-free oxidant.

[0031] It is to be noted again that the amount of the oxidant added can be adjusted according to the content of sulfite in the test solution, so as to ensure that all sulfite in the test solution is oxidized to sulfate as the ultimate goal.

[0032] According to any embodiment of the first aspect of the present invention, the oxidant comprises any one, two or three of ozone, hydrogen peroxide and bromine water.

[0033] According to any embodiment of the first aspect of the present invention, based on the 30% (w / w) oxidant solution, the added volume ratio of the oxidant solution to the test solution is 0.5% to 4%.

[0034] According to any embodiment of the first aspect of the present invention, the dosage of the gaseous oxidant is 5 to 75 wt % of the waste in S1, calculated on the basis that the oxidant is in gaseous state.

[0035] According to any embodiment of the first aspect of the present invention, if the oxidant solution is a hydrogen peroxide solution, the volume ratio of the hydrogen peroxide solution to the test solution is 0.5% to 4% calculated based on the 30% (w / w) hydrogen peroxide solution.

[0036] According to any embodiment of the first aspect of the present invention, if the oxidant solution is bromine water, the volume ratio of the bromine water to the test solution is 0.5% to 4% calculated based on the 30% (w / w) bromine water.

[0037] According to any embodiment of the first aspect of the present invention, if the oxidant solution is a solution containing hydrogen peroxide and bromine water, the added volume ratio of the oxidant solution to the test solution is 0.5% to 4% calculated based on the 30% (w / w) oxidant solution.

[0038] According to any embodiment of the first aspect of the present invention, if the oxidant solution is ozone gas, the dosage of the ozone gas is 5 to 75 wt % of the waste in S1.

[0039] According to any embodiment of the first aspect of the present invention, if the oxidant solution is a hydrogen peroxide solution, the volume ratio of the hydrogen peroxide solution to the test solution is 1% to 4% calculated based on the 30% (w / w) hydrogen peroxide solution.

[0040] According to any embodiment of the first aspect of the present invention, if the oxidant solution is bromine water, the volume ratio of the bromine water to the test solution is 1% to 4% calculated based on the 30% (w / w) bromine water.

[0041] According to any embodiment of the first aspect of the present invention, if the oxidant solution is a solution containing hydrogen peroxide and bromine water, the added volume ratio of the oxidant solution to the test solution is 1% to 4% calculated based on the 30% (w / w) oxidant solution.

[0042] According to any embodiment of the first aspect of the present invention, if the oxidant solution is ozone gas, the dosage of the ozone gas is 10 to 75 wt % of the waste in S1.

[0043] According to any embodiment of the first aspect of the present invention, in S1, when the waste is treated by oxygen bomb combustion method, the sulfur element generated during the treatment process is collected by absorption liquid to obtain a test liquid containing sulfur element;

[0044] Wherein, the absorption liquid contains 0.05-0.7 mol / L inorganic alkali solution.

[0045] According to any embodiment of the first aspect of the present invention, the absorption liquid is an inorganic alkaline solution containing 0.3 to 0.6 mol / L.

[0046] According to any embodiment of the first aspect of the present invention, the absorption liquid is a 0.05-0.7 mol / L inorganic alkaline solution.

[0047] According to any embodiment of the first aspect of the present invention, the absorption liquid is a 0.3-0.6 mol / L inorganic alkaline solution.

[0048] According to any embodiment of the first aspect of the present invention, the inorganic base includes any one or two or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, and sodium bicarbonate.

[0049] According to any embodiment of the first aspect of the present invention, in S4, the detection conditions of the ion chromatography include:

[0050] Mobile phase: ultrapure water;

[0051] Flow rate: 1.0 mL / min;

[0052] Column temperature: 30°C;

[0053] Chromatographic column: OnGuard RP column or C18 column.

[0054] Beneficial Effects

[0055] (1) The method for detecting total sulfur in waste provided by the present invention, based on the original oxygen bomb combustion method-ion chromatography detection, adds treatments including pH adjustment and oxidation treatment to the obtained test liquid, which can oxidize all sulfite existing in the test liquid into sulfate as much as possible; thereby ensuring the stability and accuracy of the subsequent ion chromatography detection results.

[0056] (2) The method for detecting total sulfur in waste provided by the present invention preferably uses an acid that has oxidizing properties or helps to create a good oxidizing environment for the subsequent oxidant to adjust the test liquid. On the basis of achieving the pH value adjustment of the test liquid, the oxidizing property of the acid can be further exerted to increase the oxidizing capacity of the oxidant in an acidic environment, so that sulfite can be oxidized to sulfate to the greatest extent, thereby improving the accuracy of ion chromatography detection of total sulfur content.

[0057] In summary, the method for detecting total sulfur in waste provided by the present invention can ensure that during the final ion chromatography detection, the sulfur in the test liquid exists in the form of sulfate ions to the greatest extent possible, and the separation degree between the sulfate ions and other anion peaks is large. Based on this, the requirements for the separation degree and column efficiency of the chromatographic column in the ion chromatography detection can be reduced, the material detection cost can be reduced, the peak shape of the sulfur element in the chromatographic column can be improved, and finally the determination accuracy of the total sulfur in the waste in the oxygen bomb combustion-ion chromatography method can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is the peak spectrum of the test solution (not treated with nitric acid or hydrogen peroxide) in Comparative Example 3 of the present invention;

[0059] Figure 2 This is a peak spectrum after the test solution is treated with nitric acid and hydrogen peroxide in an embodiment of the present invention. DETAILED DESCRIPTION

[0060] The present disclosure may be more easily understood by reference to the following description in conjunction with the accompanying drawings and examples, all of which constitute a part of the present disclosure. It should be understood that the present disclosure is not limited to the specific products, methods, conditions or parameters described and / or shown herein. Further, the terms used herein are only used for the purpose of describing specific embodiments by way of example and are not intended to be limiting unless otherwise stated.

[0061] It should be noted that the terms used here are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. It should be understood that the scope of protection of the present invention is not limited to the specific specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are for describing specific specific embodiments and are not intended to limit the scope of protection of the present invention. In the following specific embodiments, if the experimental methods of specific conditions are not indicated, they are generally in accordance with the conventional methods and conditions of molecular biology within the art, and such techniques and conditions are fully explained in the literature.

[0062] It should also be understood that, for the sake of clarity, certain features of the present disclosure may be described herein in the context of separate embodiments, but may also be provided in combination with each other in a single embodiment. That is, unless clearly incompatible or specifically not included, each separate embodiment is considered to be combinable with any other embodiment, and the combination is considered to represent another different embodiment. Conversely, for the sake of simplicity, the various features of the present disclosure described in the context of a single embodiment may also be provided individually or in any sub-combination. Finally, although a particular embodiment may be described as part of a series of steps or part of a more general structure, each step or substructure itself may also be considered to be an independent embodiment.

[0063] Unless otherwise indicated, it should be understood that each individual element in a list and each combination of individual elements in the list will be interpreted as a different embodiment. For example, a list of embodiments represented as "A, B, or C" should be interpreted to include embodiments "A", "B", "C", "A or B", "A or C", "B or C", or "A, B, or C".

[0064] In the present disclosure, the singular forms of the articles "a," "an," and "the" also include the corresponding plural references, and a reference to a specific value includes at least that specific value unless the context clearly indicates otherwise. Thus, for example, a reference to "a substance" is a reference to at least one of that substance and equivalents thereof.

[0065] The terms including ordinal numbers such as "first" and "second" can be used to explain various components or fluids, but these components and fluids are not limited by these terms. Therefore, without departing from the teachings of the present disclosure, these terms are only used to distinguish the component / fluid from another component / fluid.

[0066] When items are described by using the conjunction terms "... and / or...," etc., the description should be understood to include any one of the associated listed items and all combinations of one or more thereof.

[0067] In general, the use of the term "about" indicates an approximate value that may vary depending on the desired properties obtained by the disclosed subject matter, and will be interpreted in a context-dependent manner based on function. Therefore, one of ordinary skill in the art will be able to interpret a certain degree of difference on a case-by-case basis. In some cases, the number of significant figures used when expressing a particular value can be a representative technique for determining the difference allowed by the term "about". In other cases, a gradient in a range of values ​​can be used to determine the range of differences allowed by the term "about". Further, all ranges in this disclosure are inclusive and combinable, and reference to the values ​​stated in the range includes each value within the range.

[0068] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs; the terms used herein and / or include any and all combinations of one or more of the associated listed items.

[0069] Ion chromatography (Ic) is a method that uses the principle of ion exchange to detect and analyze anions and cations in a solution. It has the characteristics of high sensitivity, good selectivity, rapidity and simplicity, and the ability to simultaneously measure multiple ions. It has become the preferred method for detecting ion content in food, medicine, and waste.

[0070] The ion chromatography method is usually used in conjunction with the oxygen bomb combustion method to determine the content of target trace elements in a sample (hereinafter referred to as the existing oxygen bomb combustion method-ion chromatography method). The steps that can usually be used for reference are as follows:

[0071] Step 1. Treating the waste by oxygen bomb combustion to obtain a test solution containing sulfur;

[0072] Wherein, the sulfur element is derived from the waste;

[0073] Step 2. Detect the sulfur content in the test solution using ion chromatography.

[0074] Regarding the “step 1) treating the waste by oxygen bomb combustion method to obtain a test liquid containing sulfur element;” more specifically:

[0075] When the waste is treated by oxygen bomb combustion method, the sulfur element generated in the treatment process is collected by absorption liquid to obtain the test liquid containing sulfur element.

[0076] The absorption liquid is usually a 0.05-0.7 mol / L inorganic alkali solution, such as 0.1 mol / L sodium hydroxide solution, 0.2 mol / L sodium hydroxide solution, 0.3 mol / L sodium hydroxide solution, 0.4 mol / L sodium hydroxide solution, 0.5 mol / L sodium hydroxide solution, 0.6 mol / L sodium hydroxide solution, 0.7 mol / L sodium hydroxide solution, 0.1 mol / L potassium hydroxide solution, 0.2 mol / L potassium hydroxide solution, 0.3 mol / L sodium hydroxide solution, L potassium hydroxide solution, 0.4mol / L potassium hydroxide solution, 0.5mol / L potassium hydroxide solution, 0.6mol / L potassium hydroxide solution, 0.7mol / L potassium hydroxide solution, 0.1mol / L lithium hydroxide solution, 0.2mol / L lithium hydroxide solution, 0.3mol / L lithium hydroxide solution, 0.4mol / L lithium hydroxide solution, 0.5mol / L lithium hydroxide solution, 0.6mol / L lithium hydroxide solution, 0.7mol / L lithium hydroxide solution,

[0077] A mixed solution of sodium hydroxide and potassium hydroxide with a total concentration of 0.1 mol / L, a mixed solution of sodium hydroxide and potassium hydroxide with a total concentration of 0.2 mol / L, a mixed solution of sodium hydroxide and potassium hydroxide with a total concentration of 0.3 mol / L, a mixed solution of sodium hydroxide and potassium hydroxide with a total concentration of 0.4 mol / L, a mixed solution of sodium hydroxide and potassium hydroxide with a total concentration of 0.5 mol / L, a mixed solution of sodium hydroxide and potassium hydroxide with a total concentration of 0.6 mol / L, and a mixed solution of sodium hydroxide and potassium hydroxide with a total concentration of 0.7 mol / L.

[0078] Based on this, one of the methods for reference in the step 1) treating the waste by oxygen bomb combustion to obtain a test liquid containing sulfur is:

[0079] Weigh 0.1-0.5 g of the waste to be tested into a clean and dried crucible, and add 5-10 ml of an absorption liquid with an alkali concentration of 0.4-0.7 mol / L into the absorption cup of the oxygen bomb as absorption liquid-A;

[0080] Put the crucible with the waste weighed and the absorption cup with absorption liquid-A into the oxygen bomb, install the ignition wire, make sure the ignition wire is energized and in contact with the waste to be tested, and then tighten the oxygen bomb cover;

[0081] Inject oxygen into the oxygen bomb until the pressure reaches (2.5±0.2)MPa. After the first inflation, slowly release the gas and then fill it with oxygen for the second time. After the oxygen pressure reaches (2.5±0.2)MPa, stabilize it for 10-15s. Ignite and burn until the combustion is finished. After standing for 5-10 minutes, open the exhaust valve and slowly pass the burned gas into a 200ml volumetric flask pre-filled with 100ml absorption liquid-B with an alkali concentration of 0.05-0.3mol / L.

[0082] After the oxygen bomb is pressurized to normal pressure, open the oxygen bomb, wash the crucible, absorption cup and oxygen bomb with ultrapure water, transfer the washing liquid, absorption liquid-A and the residue after combustion to a volumetric flask, make up the volume, and shake well to obtain the test solution.

[0083] More specifically, regarding the above “2) using ion chromatography to detect the sulfur content in the test solution”:

[0084] One of the chromatographic conditions for reference is:

[0085] Mobile phase: ultrapure water;

[0086] Flow rate: 1.0 mL / min;

[0087] Column temperature: 30°C;

[0088] Chromatographic column: OnGuard RP column or C18 column.

[0089] One of the operation steps for reference is:

[0090] Turn on the ion chromatograph according to the instrument operating procedures and test conditions. After the baseline is balanced, filter the test solution through a 0.22μm aqueous filter membrane. The filtered test solution is injected into the instrument. After chromatographic analysis, a spectrum is obtained. The sulfur content in the sample waste is calculated by the peak area of ​​sulfate (the total sulfur content is calculated using sulfate).

[0091] In addition, the calculation formula (1) described in the calculation is as follows:

[0092] ω=(ρ×V×D) / (m×10000)

[0093] in:

[0094] ρ represents the concentration of anions in the test solution, mg / L;

[0095] V represents the fixed volume of the test solution or the total volume of the extract, mL;

[0096] D represents the dilution multiple of the test solution or extract;

[0097] m represents the weight of the waste, g;

[0098] 10000 represents the conversion factor of mg / kg to %.

[0099] The method for detecting total sulfur in waste provided by the present invention is actually an improved solution based on the above-mentioned "existing oxygen bomb combustion method-ion chromatography method". The improvement of the technical solution of the present invention comes from the fact that the inventors found in the actual detection process using the above-mentioned "existing oxygen bomb combustion method-ion chromatography method" that Figure 1 As shown in the figure, the calculation of the total sulfur (sulfite + sulfate) content in the sample will be biased because the sulfite peak in the ion chromatograph is wide and has severe tailing; especially when the ion chromatographic column efficiency decreases, the sulfite peak position will increasingly overlap with the sulfate peak position, resulting in an increasingly large analysis error. Based on the above findings, the frequency of replacement of ion chromatographic columns during the detection process is forced to increase, thereby increasing the detection cost.

[0100] The method for detecting total sulfur in waste provided by the present invention comprises the following steps:

[0101] S1 uses an oxygen bomb combustion method to treat the waste to obtain a test liquid containing sulfur element;

[0102] Wherein, the sulfur element comes from the waste (same as the aforementioned Step 1.);

[0103] S2 adjusting the pH value of the test solution to 2.8-4.0;

[0104] S3 performs oxidation treatment on the liquid to be tested;

[0105] S4 uses ion chromatography to detect the sulfur content in the test solution (same as the aforementioned Step 2).

[0106] More specifically, the step S2 of adjusting the pH value of the test solution to 2.8 to 4.0 is as follows:

[0107] The pH value is adjusted by using an acid solution; firstly, the acid is required to be free of sulfur and not to react with the sulfur element to form a precipitate. On this basis, it is preferred to use an acid that is oxidizing or helps to create a good oxidizing environment for the subsequent oxidant to adjust the test solution. Based on this, any one, two or three of hydrochloric acid, nitric acid and phosphoric acid can be cited. If the acid contains any two or three of hydrochloric acid, nitric acid and phosphoric acid at the same time, the various acids can be mixed in any proportion.

[0108] There is no specific limitation or requirement on the pH value or concentration of the acid solution itself, and priority may be given to easy operation and easy control of precision, and it can be flexibly adjusted according to actual conditions.

[0109] Commonly used acid concentrations for reference include: 1-3 mol / L nitric acid solution; 1-3 mol / L hydrochloric acid solution; 1-2 mol / L phosphoric acid solution.

[0110] Regarding the aforementioned “step S3 of performing oxidation treatment on the test liquid;” more specifically:

[0111] The liquid to be tested is oxidized by a sulfur-free oxidant that does not react with the sulfur element to form a precipitate. On this basis, for example, any one, two or three oxidant solutions of ozone, hydrogen peroxide and bromine water are cited, and the added volume ratio of the oxidant solution to the liquid to be tested is 0.5% to 4% based on the 30% (w / w) oxidant solution. If the oxidant is gaseous, the dosage of the gaseous oxidant is 5 to 75 wt% / min of the waste in S1. More specifically:

[0112] If the oxidant solution is a hydrogen peroxide solution, then based on the 30% (w / w) hydrogen peroxide solution, the added volume ratio of the hydrogen peroxide solution to the test solution is 0.5% to 4%; preferably, the added volume ratio is 1% to 4%;

[0113] If the oxidant solution is bromine water, the volume ratio of the bromine water to the test solution is 0.5% to 4% based on the 30% (w / w) bromine water; preferably, the volume ratio is 1% to 4%.

[0114] If the oxidant solution is a solution containing hydrogen peroxide and bromine water, the volume ratio of the oxidant solution to the test solution is 0.5% to 4% based on the 30% (w / w) oxidant solution; preferably, the volume ratio is 1% to 4%.

[0115] If the oxidant solution is ozone gas, the dosage of the ozone gas is 5-75wt% of the waste in S1; preferably, the dosage of the ozone gas is 10-75wt% of the waste in S1.

[0116] It should be noted that, as described above, if ozone gas is selected as the oxidant, the present invention provides two ozone gas addition methods for reference:

[0117] The first method is to place the test liquid in a closed environment, then inject ozone gas once and let it stand in a closed environment for 5 to 15 minutes;

[0118] The second type: the dosage of the ozone gas is 5-10wt% / min (preferably 8-10wt% / min) of the waste in S1, and the entire ozone input is completed within 5min-15min.

[0119] Finally, it should be noted that, in fact, for any "concentration" or "ratio" mentioned in the present invention, it is necessary to consider all the inevitable errors that may occur in the actual operation process. Based on this, the endpoint values ​​of the given numerical range include the numerical range in which the digits to the right of the decimal point of the value are 1 digit or more.

[0120] For the "pH value" mentioned in the present invention, all the inevitable errors that may occur in the actual operation process should also be considered. Based on this, the pH value of 2.8, 3.0 or 4.0 mentioned here does not refer to a fixed endpoint value in actual situations, but a numerical range containing many values, more specifically, including the numerical range of the number to the right of the decimal point of the value is 2 digits and above, and rounding is followed. In addition, we believe that this is reasonable and necessary, because approximate terms such as "about" represent different variables rather than the rounded values ​​themselves, and measuring the precise pH value is impossible in practice, which is also impossible (realizable) in science.

[0121] The present invention is further described below in conjunction with specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art. The essential characteristics and remarkable effects of the present invention can be reflected from the following examples, and the described embodiments are part of the embodiments of the present invention, rather than all the embodiments, and therefore, they do not limit the present invention in any way, and those skilled in the art make some non-essential improvements and adjustments based on the content of the present invention, which all belong to the protection scope of the present invention.

[0122] Example

[0123] In this embodiment, sulfur-containing sludge is used as the waste sample to be tested, and the total sulfur is detected.

[0124] In this embodiment, the following method is used to detect the total sulfur in the waste, and the specific steps are as follows:

[0125] S1 treats the waste by oxygen bomb combustion to obtain an absorption liquid containing sulfur element;

[0126] The specific operation is as follows: Suggested operation steps: weigh 0.1-0.5g of sludge and place it in a clean and dry crucible, add 10ml of 0.5mol / L potassium hydroxide solution into the absorption cup of the oxygen bomb as absorption liquid-A;

[0127] Put the crucible with weighed sludge and the absorption cup with absorption liquid-1 into the oxygen bomb, install the ignition wire, make sure it is energized and in contact with the sample, tighten the oxygen bomb cover, and introduce oxygen into the oxygen bomb until the pressure is (2.5±0.2)MPa;

[0128] After the first inflation, slowly release the gas and then fill with oxygen for the second time. After the oxygen pressure reaches (2.5±0.2)MPa, stabilize for 10-15s, ignite and burn until the combustion is completed. After standing for 5-10 minutes, open the exhaust valve and slowly pass the burned gas into a 200ml volumetric flask pre-filled with 100ml of 0.1mol / L potassium hydroxide solution (as absorption liquid-B). After the oxygen bomb pressure reaches normal pressure, open the oxygen bomb, wash the crucible, absorption cup and oxygen bomb with ultrapure water, transfer all the washing liquid and absorption liquid-A to the volumetric flask, make up to volume, and shake well to obtain the test solution.

[0129] S2 adjusting the pH value of the test solution to 3;

[0130] The specific operation is as follows: after transferring all the absorption liquid to be tested to a volumetric flask, add deionized water to 2 / 3 of the fixed volume, and adjust the pH of the absorption liquid to be tested in the volumetric flask to 3.0 with 2 mol / L nitric acid solution;

[0131] S3 performs oxidation treatment on the solution to be tested after adjusting the pH value;

[0132] The specific operation is as follows: then add 2 ml of 30% hydrogen peroxide solution at a volume ratio of 98:2 (i.e., add 2 ml of 30% hydrogen peroxide solution to a 100 ml volumetric flask), then make up to volume with deionized water, shake well and then test.

[0133] S4 uses ion chromatography to detect the sulfur content in the absorption liquid.

[0134] The specific operations are as follows:

[0135] Turn on the ion chromatograph according to the instrument operating procedures and test conditions. After the baseline is balanced, filter the sample solution through a 0.22μm aqueous filter membrane. The filtered sample solution is injected into the instrument. After chromatographic analysis, the spectrum is obtained. The sulfur content in the sample is calculated by the peak area of ​​sulfate. (Sulfous acid has been oxidized to sulfuric acid, and the total sulfur content is calculated using sulfate)

[0136] The detection conditions of the ion chromatography method include:

[0137] Mobile phase: ultrapure water;

[0138] Flow rate: 1.0 mL / min;

[0139] Column temperature: 30°C;

[0140] Chromatographic column: OnGuard RP column or C18 column.

[0141] Its peak spectrum is as follows Figure 2 shown.

[0142] According to the test results, the calculation result is obtained according to the calculation formula (1) as described above.

[0143] Comparative Example

[0144] The method for detecting total sulfur in waste provided in this comparison is basically the same as that in the embodiment, with the difference as shown in Table 1. The waste samples in this comparative example are the same as those in the embodiment.

[0145] Table 1. Comparative Examples 1 to 5

[0146]

[0147]

[0148] Based on the conditions shown in Table 1, combined Figure 2 It can be seen that compared with Comparative Example 3 (its peak spectrum is as shown in Figure 1 As shown, in the embodiment of the present invention, the liquid to be tested after combustion in the oxygen bomb is reprocessed, and the sulfite in the liquid to be tested is oxidized into sulfate with a hydrogen peroxide solution under nitric acid acidification conditions. By adding a dilute nitric acid solution to the liquid to be tested, acidic conditions can be created for the sulfite to be oxidized by hydrogen peroxide, and the oxidizing ability of hydrogen peroxide can be increased by the oxidizing property of the dilute nitric acid, so that the sulfite is oxidized into sulfate to the greatest extent, thereby improving the accuracy of detecting the total sulfur content, reducing the requirements for the accuracy of the chromatographic column, reducing the frequency of replacing the chromatographic column, and saving the use cost of the chromatographic column.

[0149] Further explanation is given in conjunction with Table 1:

[0150] 1) In comparative example 1, step S2 is not performed. The effect of this condition change is that the test solution generated by the alkaline test solution absorbing the acidic gas after combustion is an alkaline solution, and the oxidizing property of hydrogen peroxide in an alkaline solution is not as strong as that in an acidic solution. After the operation of S2, the test solution can be converted into an acidic solution, which is more conducive to the oxidation of sulfurous acid by hydrogen peroxide in step S3, and the amount of hydrogen peroxide used can be saved.

[0151] In addition, the solid residue (sulfite) transferred after combustion is more easily dissolved or decomposed under acidic water conditions.

[0152] 2) In comparative example 2, step S3 is not performed. The impact of this condition change is: if the operation of S3 is not performed, the sulfur element in the test liquid may exist in two forms of sulfite and sulfate. Through the oxidation of hydrogen peroxide in S2, the sulfur element in the test liquid will only exist in one form (sulfate), which can reduce the detection data deviation caused by the peak area (deviation: the deviation of the total sulfur content calculated by the two peaks is larger, and the sulfite is unstable), and it is easier to calculate the total sulfur content, and the separation degree of each peak in the spectrum can be greater.

[0153] 3) In comparative example 3, steps S2 and S3 are not performed. The impact of this condition change is as follows: for samples with low calorific value or large and tightly packed particles or high sulfur content, incomplete combustion will occur when there is sufficient oxygen. The sulfur element coexists in the flue gas and residue after combustion in the form of sulfite and sulfate. When ion chromatography is used to determine the sulfur element, the total sulfur needs to be calculated through the two peaks of sulfate and sulfite, which is not only inconvenient, but also has a large deviation (sulfite is not stable enough), and it is impossible to perform repeatable experiments.

[0154] 4) In step S2 of comparative example 4, the pH is adjusted to 7-8. The effect of this condition change is that the oxidizing property of hydrogen peroxide in an environment of pH 2.8-4.0 is stronger than that in an environment of pH 7-8, resulting in different amounts of hydrogen peroxide used.

[0155] 5) Effect of the change in conditions in Example 5: When hydrogen peroxide is added to the absorption liquid before combustion, hydrogen peroxide only partially oxidizes the flue gas during the combustion process, and the oxidation efficiency is very low; and hydrogen peroxide is more easily decomposed into oxygen at high temperatures, and is more used to provide oxygen, while the oxidizing property of hydrogen peroxide cannot be brought into optimal state. And after the oxygen bomb is burned, the remaining hydrogen peroxide is almost zero, and it has no oxidation ability to the residue transferred after combustion, but in the actual process, the proportion of sulfite contained in the residue after combustion is larger.

[0156] In addition, whether the waste to be tested is fully burned during the actual combustion process is not only related to the amount of oxygen, but also to the structure of the waste to be tested itself, such as: particle size, whether it is fluffy (activated carbon particles or activated carbon powder), sulfur content or sample weight, and the calorific value of the waste to be tested itself.

[0157] In addition, the influence of the fluffiness of the waste to be tested on combustion is given as an example: activated carbon itself has a high calorific value. When activated carbon exists in the form of particles, the interior is tightly wrapped and oxygen cannot enter the interior for complete combustion. When activated carbon exists in the form of powder, it burns more completely.

Claims

1. A method for detecting total sulfur in waste, characterized in that: The following steps are involved: S1 uses an oxygen bomb combustion method to treat the waste to obtain a test liquid containing sulfur element; Wherein, the sulfur element is derived from the waste; S2 adjusting the pH value of the test solution to 2.8-4.0; S3 performs oxidation treatment on the liquid to be tested; S4 uses ion chromatography to detect the sulfur content in the test solution.

2. The method for detecting total sulfur in waste according to claim 1, characterized in that: In S2, the pH value is adjusted using acid; The acid does not contain elemental sulfur and does not react with the elemental sulfur to form a precipitate.

3. The method for detecting total sulfur in waste according to claim 1, characterized in that: In S2, the pH value is adjusted using acid; The acid includes any one, two or three of hydrochloric acid, nitric acid and phosphoric acid.

4. The method for detecting total sulfur in waste according to any one of claims 1 to 3, characterized in that: In S3, the test solution is oxidized by using a sulfur-free oxidant.

5. The method for detecting total sulfur in waste according to claim 4, characterized in that: Calculated based on the 30% (w / w) oxidant solution, the added volume ratio of the oxidant solution to the test solution is 0.5% to 4%; Alternatively, based on the calculation that the oxidant is in gaseous state, the dosage of the gaseous oxidant is 5 to 75 wt % of the waste in S1.

6. The method for detecting total sulfur in waste according to claim 4, characterized in that: The oxidant includes any one, two or three of ozone, hydrogen peroxide and bromine water; If the oxidant solution is a hydrogen peroxide solution, the volume ratio of the hydrogen peroxide solution to the test solution is 0.5% to 4% calculated based on the 30% (w / w) hydrogen peroxide solution; If the oxidant solution is bromine water, the volume ratio of the bromine water to the test solution is 0.5% to 4% based on the 30% (w / w) bromine water. If the oxidant solution is a solution containing hydrogen peroxide and bromine water, the volume ratio of the oxidant solution to the test solution is 0.5% to 4% based on the 30% (w / w) oxidant solution; If the oxidant solution is ozone gas, the dosage of the ozone gas is 5-75wt% of the waste in S1.

7. The method for detecting total sulfur in waste according to claim 6, characterized in that: The oxidant includes any one, two or three of ozone, hydrogen peroxide and bromine water; If the oxidant solution is a hydrogen peroxide solution, the added volume ratio of the hydrogen peroxide solution to the test solution is 1% to 4% based on the 30% (w / w) hydrogen peroxide solution; If the oxidant solution is bromine water, the volume ratio of the bromine water to the test solution is 1% to 4% calculated based on the 30% (w / w) bromine water; If the oxidant solution is a solution containing hydrogen peroxide and bromine water, the volume ratio of the oxidant solution to the test solution is 1% to 4% based on the 30% (w / w) oxidant solution. If the oxidant solution is ozone gas, the dosage of the ozone gas is 10-75 wt % of the waste in S1.

8. The method for detecting total sulfur in waste according to any one of claims 1 to 3, characterized in that: In S1, when the waste is treated by oxygen bomb combustion method, sulfur element generated during the treatment process is collected by absorption liquid to obtain a test liquid containing sulfur element; Wherein, the absorption liquid contains 0.05-0.7 mol / L inorganic alkali solution.

9. The method for detecting total sulfur in waste according to claim 8, characterized in that: The inorganic base includes any one or two or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate and sodium bicarbonate.

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