阅读说明：本技术 一种采集空气中氨的固体吸附剂的制备方法及采样管 (Preparation method of solid adsorbent for collecting ammonia in air and sampling pipe ) 是由 付朝晖 许志珍 魏志勇 郭玲 王东旭 谢昊涵 于 2021-08-04 设计创作，主要内容包括：本发明提供了一种采集空气中氨的固体吸附剂的制备方法,包括：(1)吸附介质的净化,利用粒径为20-40目的活性炭为吸附介质,采用稀酸和纯水交替洗脱净化所述吸附介质；(2)净化吸附介质的改性处理：将甲烷磺酸或硫酸加入净化后的所述吸附介质中来进行改性处理,相对于所述吸附介质的质量,加入的甲烷磺酸质量为8-12％,优选10％,或加入的硫酸的质量为5％-12％；以及(3)改性吸附介质的干燥；对将改性处理所得的溶液混合物加热,以蒸发其中的2/5-2/3体积的液体,然后在干燥箱中干燥,直到蒸干剩余的液体,由此制得所述固体吸附剂。(The invention provides a preparation method of a solid adsorbent for collecting ammonia in air, which comprises the following steps: (1) purifying an adsorption medium, namely, using active carbon with the particle size of 20-40 meshes as the adsorption medium, and alternately eluting and purifying the adsorption medium by using dilute acid and pure water; (2) modification treatment of the purification adsorption medium: adding methane sulfonic acid or sulfuric acid into the purified adsorption medium for modification treatment, wherein the mass of the added methane sulfonic acid is 8-12%, preferably 10% relative to the mass of the adsorption medium, or the mass of the added sulfuric acid is 5-12%; and (3) drying the modified adsorbent media; heating the solution mixture obtained by the modification treatment to evaporate 2/5-2/3 volume of liquid therein, and then drying in a drying oven until the remaining liquid is evaporated to dryness, thereby preparing the solid adsorbent.)

1. A method for preparing a solid adsorbent for collecting ammonia in air, comprising:

(1) purifying an adsorption medium, namely, using active carbon with the particle size of 20-40 meshes as the adsorption medium, and alternately eluting and purifying the adsorption medium by using dilute acid and pure water;

(2) modification treatment of the purification adsorption medium: adding methane sulfonic acid or sulfuric acid into the purified adsorption medium for modification treatment, wherein the mass of the added methane sulfonic acid is 8-12%, preferably 10% relative to the mass of the adsorption medium, or the mass of the added sulfuric acid is 5-12%; and

(3) drying the modified adsorption medium; heating the solution mixture obtained by the modification treatment to evaporate 2/5-2/3 volume of liquid therein, and then drying in a drying oven until the remaining liquid is evaporated to dryness, thereby preparing the solid adsorbent.

2. The method according to claim 1, wherein in the step (1), the adsorption medium after elution is detected by ion chromatography, wherein the purification rate of ammonium ions is more than 99.0%, and the purification rate of the remaining cations is 95-100%.

3. The method according to claim 1, wherein in step (1), the dilute acid is a dilute sulfuric acid solution or a dilute hydrochloric acid solution.

4. A solid sorbent sampling tube for ammonia capture in air, comprising utilizing a solid sorbent prepared according to the method of any one of claims 1-3 as a sorbent for the sampling tube.

5. The sampling tube of claim 4, wherein the sorbent in the sampling tube is divided into a front section and a rear section, both ends of the sorbent and the middle of the front and rear sections are fixed with glass wool or polyurethane foam, and both ends of the sampling tube are sealed by fusing.

6. The sampling tube of claim 4, wherein the sampling tube has a length of 70-90mm, an inner diameter of 3.5-4.0 mm, and an outer diameter of 5.5-6.0 mm.

7. The sampling tube of claim 4, wherein the sampling tube has an ammonia breakthrough capacity greater than 1600 μ g at a 200mg fill.

8. The sampling tube of claim 4, wherein the ammonia desorption efficiency after sampling is 100-104%.

9. The sampling tube of claim 8, wherein the desorption is performed using deionized water.

10. A method of collecting ammonia in air, comprising collecting ammonia in air using a sampling tube according to any of claims 5-9.

Technical Field

The invention relates to the technical field of environmental and sanitary detection, in particular to a preparation method of a solid adsorbent for collecting ammonia in air and a sampling pipe.

Background

Ammonia is colorless gas, has a low boiling point, is very easy to liquefy into colorless liquid ammonia, is often used as a refrigerant, is also an important chemical raw material for manufacturing nitric acid, chemical fertilizers, resins, plastics and the like, is widely applied in industrial production in China, has more occupational contact groups, and is a common occupational disease hazard factor. Meanwhile, ammonia is also an important additive for building materials, refrigeration devices, household detergents and the like, may cause air pollution in the environment or public places, and is an important air pollutant. Ammonia has strong irritation and corrosion effects on eyes, nose, throat, skin and the like of a human body, and can affect the health of the human body at a certain concentration. The relevant standards in the fields of environmental protection, public health and occupational health all set limits for ammonia in the air.

Regarding the sampling method of ammonia in air, most of the current national and industrial standards in the fields of environmental protection, public health and occupational health in China adopt sulfuric acid (HJ 534-. Although the acid solution is absorbed and collected in the detection process, the sample does not need a complex pretreatment process, but the method has many defects in the practical application process, such as the fact that the absorption solution is corrosive and consumes a lot of energy, the absorption tube is easy to break and is not suitable for long-distance carrying, the sampling personnel need to strengthen individual protection, and the method is not suitable for individual sampling, and the sample storage time limit is short. With the continuous improvement of the detection requirements of chemical harmful factors in environmental air and waste gas in China and air in public places and workplaces, the sampling method of ammonia in air needs to be improved urgently. The solid adsorbent sampling tube can make up the defects of an absorption liquid collecting method, is easy to transport in a long distance, is convenient to carry, has long sample storage time, and can be used for sampling occupational health individuals. However, the currently available adsorbent tubes in China are mainly silica gel tubes and activated carbon tubes, and have the problems of large blank of ammonium ions or other cations, interference with measurement results, poor stability, low penetration capacity and the like, and are not suitable for collecting ammonia in the air.

Therefore, there is a need for new technical approaches to at least partially address the deficiencies of the prior art.

Disclosure of Invention

In order to at least partially solve the problems in the prior art, the invention provides a preparation method of a solid adsorbent for collecting ammonia in air, a sampling tube and a sampling method, which can make up the defects of the method for collecting absorption liquid, are convenient to carry, easy to transport in a long distance, can be used for individual sampling, and are suitable for collecting ammonia in air in the detection fields of environmental protection, public health and occupational health.

According to an aspect of the present invention, there is provided a method for preparing a solid adsorbent for capturing ammonia in air, comprising:

(1) purifying an adsorption medium, namely, using active carbon with the particle size of 20-40 meshes as the adsorption medium, and alternately eluting and purifying the adsorption medium by using dilute acid and pure water;

(2) modification treatment of the purification adsorption medium: adding methane sulfonic acid or sulfuric acid into the eluted adsorption medium for modification treatment, wherein the mass of the added methane sulfonic acid is 8-12%, preferably 10% or the mass of the added sulfuric acid is 5-12% of the mass of the adsorption medium; and

(3) drying the modified adsorption medium; heating the solution mixture obtained by the modification treatment to evaporate 2/5-2/3 volume of liquid therein, and then drying in a drying oven until the remaining liquid is evaporated to dryness, thereby preparing the solid adsorbent.

According to an embodiment of the present invention, in the step (1), the adsorption medium after elution is detected using ion chromatography, wherein the purification rate of ammonium ions is more than 99.0%, and the purification rate of the remaining cations is 95 to 100%.

According to an embodiment of the invention, in step (1), the dilute acid is a dilute sulfuric acid solution or a dilute hydrochloric acid solution.

According to another aspect of the present invention, there is provided a solid adsorbent sampling tube for ammonia capture in air, characterized by comprising a solid adsorbent prepared by the method according to the present invention as an adsorbent for the sampling tube.

According to an embodiment of the present invention, the adsorbent in the sampling tube is divided into a front section and a rear section, both ends of the adsorbent and the middle of the front and rear sections are fixed with glass wool or polyurethane foam, and both ends of the sampling tube are sealed by fusing.

According to an embodiment of the invention, the sampling tube has a length of about 70-120mm, e.g. 70-90mm, an inner diameter of 3.5-4.0 mm and an outer diameter of 5.5-6.0 mm.

According to an embodiment of the invention, the ammonia breakthrough capacity of the sampling tube is greater than 1600 μ g, filled at a gauge of about 200 mg.

According to an embodiment of the present invention, the ammonia desorption efficiency after sampling is 100-104%.

According to an embodiment of the invention, the desorption is performed with deionized water.

According to a further aspect of the invention there is provided a method of collecting ammonia in air comprising collecting ammonia in air using a sampling tube according to the invention.

The ammonia adsorbent sampling tube developed by the technology is convenient for long-distance transportation, long in sample storage time limit, good in stability, large in penetration capacity and high in desorption efficiency, fills the blank of the ammonia adsorbent sampling tube in air in China, can bring great work convenience for related detection personnel, and is beneficial to improving the sampling work efficiency; in addition, the ammonia adsorbent sampling pipe developed by the technology can be used for individual sampling of ammonia-involved workers in the field of occupational health, the actual ammonia exposure condition of the workers can be reflected by the individual sampling result, more favorable protective measures can be taken conveniently, and the sampling pipe has great social significance and practical value for guaranteeing the health of the ammonia-involved workers.

Drawings

Some specific embodiments of the invention will be described in detail hereinafter, by way of illustration and not limitation, with reference to the accompanying drawings. The objects and features of the present invention will become more apparent in view of the following description taken in conjunction with the accompanying drawings, in which:

fig. 1 is a schematic flow chart of a method for preparing a solid adsorbent for capturing ammonia in air according to an embodiment of the present invention.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application shall fall within the scope of protection of the present application.

Referring to fig. 1, an embodiment of the present invention provides a method for preparing a solid adsorbent for capturing ammonia in air, including:

(1) purification of the adsorption medium: in this example, activated carbon with a particle size of 20-40 mesh was selected as the adsorption medium. According to the invention, the activated carbon generally contains cationic impurities such as sodium, ammonium, potassium, calcium, magnesium and the like, and the content of the impurities in a sample is respectively as high as 78.5 mu g/g, 0.14 mu g/g, 468.5 mu g/g, 1.68 mu g/g and 1.20 mu g/g. These impurities affect the measurement of ammonia at a later stage, and therefore, a purification treatment is required. In the present embodiment, a method of alternately eluting a dilute acid and pure water (e.g., deionized water) may be employed. For example, a 0.005M dilute sulfuric acid solution, a 0.01M dilute hydrochloric acid, or the like can be used. After the activated carbon is purified, the purification rate of ammonium ions in the activated carbon can reach over 99.0 percent and the purification rates of other cations can reach 95 to 100 percent by applying ion chromatography detection.

(2) Modification treatment of the purification adsorption medium: aiming at the chemical characteristics of ammonia, the modification treatment of the adsorption medium is a key problem to be solved for developing a high-efficiency ammonia adsorbent tube. In the present embodiment, the modification treatment may be performed using methanesulfonic acid or sulfuric acid. Methane sulfonic acid or sulfuric acid is added to the purified activated carbon, the mass of methane sulfonic acid added may be 8-12%, for example 10%, relative to the mass of the adsorption medium, or the mass of sulfuric acid added may be 5-12%. The methane sulfonic acid or sulfuric acid added may be of high concentration, in which case a quantity of deionized water may be added to submerge the activated carbon, or a low concentration of methane sulfonic acid or sulfuric acid in aqueous solution may be added until the activated carbon is covered. Thereafter, the modification treatment is carried out by stirring for a certain period of time, for example, 20 to 60min, for example, 30 min.

Drying the modified adsorption medium: the modified activated carbon and acid solution mixture is heated, for example, with a hot plate in a fume hood at 200-300 ℃ to boil it to evaporate 2/5-2/3 volumes of liquid therein, for example, to about half the volume of liquid, and then dried in a drying oven until the remaining liquid is evaporated. The resulting adsorbent media may then be further dried in a dryer, thereby producing the solid adsorbent.

After the solid adsorbent is prepared, the adsorbent can be used to prepare a sampling tube. The requirements of the sampling tube, such as size, etc., may be designed according to the state of the art, such as relevant national standards. For example, a glass tube having a length of about 70 to 120mm, for example 70 to 90mm, for example 80mm, an inner diameter of 3.5 to 4.0mm and an outer diameter of 5.5 to 6.0mm may be used. The solid adsorbent is filled into a tube, which may be filled in two stages according to relevant standards, for example, a glass tube at a specification of 200mg/100 mg. The two ends of the adsorbent and the middle of the front section and the rear section are fixed by glass wool or polyurethane foam plastic or other suitable materials, and after the adsorbent is installed, the two ends of the glass tube can be sealed by an alcohol blast burner, so that the solid adsorbent sampling tube is prepared. Of course, other sizes of tubes may be used, and the filling may be performed in other manners or amounts, depending on the actual requirements.

Examples

Adsorption medium: active carbon with particle size of 20-40 meshes

Purifying agent: 0.005M dilute sulfuric acid

Modifying agent: 10% methanesulfonic acid, 5% sulfuric acid, 10% sulfuric acid

Desorbing agent: deionized water

Sampling tube: the two-section specification is filled with 200mg/100mg, the length of the tube is 80mm, the inner diameter is 3.8mm, and the outer diameter is 5.6mm

1. Desorption efficiency experiment of adsorbent sampling tube

Three prepared sampling tubes are divided into three groups of 18 tubes, each group comprises 6 tubes, and 3 doses of ammonia standard solutions of 75, 150 and 300 mu g are respectively added, wherein the adding amount is m 2. The sampling tube was sealed and left overnight. The active carbon in the tube is poured into a desorption bottle, 10mL of deionized water is added, the tube is sealed, desorption is carried out for 45min, shaking is carried out at intervals, the desorption solution is used for measurement, then the amount of ammonia (m1) in each branch tube is measured by adopting ion chromatography, the desorption efficiency is m1/m2 multiplied by 100 percent, the result is shown in table 1, the desorption efficiency of the adsorbent sampling tube modified by different acid solutions can reach 100.6-103 percent, and the method and the sampling tube have good desorption efficiency.

Table 1 desorption efficiency of adsorbent sampling tube (n ═ 6)

Adsorbent tube	Desorption efficiency (%)	RSD(％)
			10% methane sulfonic acid modified pipe	100.6	2.85
5% sulfuric acid modified pipe	103	1.42
			10% sulfuric acid modified pipe	103	0.55

2. Penetration capacity test of adsorbent sampling tube

Adopts a microcomputer gas distribution instrument with the distribution limit of 40mg/m³The relative humidity of the left and right experimental gases is controlled to be 80% under the flow of 0.1L/min, the prepared adsorbent sampling pipes are used for collecting 2h, 4h, 6h and 8h respectively, and the ammonia amount in the front section and the rear section of the adsorbent pipe is measured by ion chromatography. When the amount of ammonia in the rear section is equal to 5% of that in the front section, the ammonia amount in the front section is the breakthrough capacity. The results show that: when the sampling time is 2-8h, the front section of the prepared adsorbent tube is not penetrated, the adsorption quantity of the front section is shown in Table 2, the penetration capacity of the prepared ammonia adsorbent tube is larger than 1600 mug, and the minimum penetration capacity is 1651.5 mug; the breakthrough capacity of the sulfuric acid-modified tube was even greater than 1700 μ g.

TABLE 2 adsorption capacity of adsorbent sampling tubes at different times

3. Sampling efficiency experiment of adsorbent sampling tube

Using a microcomputer gas distribution instrument to connect ammonia standard gas and high-purity nitrogen gas, the preparation concentration is 10 and 40mg/m³The experimental gas of (1) is sampled 3 times by adopting two different sampling flow rates (0.1 and 0.5L/min), and the ammonia amount m in the front and rear sections of the sampling pipe is respectively measured₁And m₂. The sampling efficiency of the front section of the sampling pipe is m₁/(m₁+m₂) X 100%. The prepared sampling tube has no ammonia amount detected in the rear section under 2 different concentrations and sampling flow rates, and the sampling efficiency is 100%.

4. Stability test of sorbent sampling tube

36 samples of each prepared adsorbent sampling tube are respectively taken, 10 mu g of ammonia standard solution is added into each tube, the tubes are placed in a closed manner at room temperature, 6 samples are respectively measured on the day, the 3 rd day, the 5 th day, the 7 th day, the 10 th day and the 14 th day, and the measurement mean value of the day is m₁The average value of the storage days is m₂The rate of decrease is (m)₁-m₂)/m₁X 100%, and the days with the reduction rate less than or equal to 10% are the stabilization time. Table 3 shows the reduction rate of the prepared three ammonia adsorbent tubes stored at room temperature for 1-14 days, and the results show that: when the three ammonia adsorbent tubes are stored for 14 days at room temperature, the reduction rates are respectively 1.72%, 4.48% and 2.48%, are respectively less than 5%, and are obviously less than 10%, the stability is good, and the related standard requirements are met.

TABLE 3 stability of sorbent sampling tubes

Although the present application has been described in terms of embodiments, those of ordinary skill in the art will recognize that there are numerous variations and permutations of the present application without departing from the spirit of the application, and it is intended that the appended claims encompass such variations and permutations without departing from the spirit of the application.