CN107202865B - Rapid detection method of heavy metal stability and toxicity in domestic waste incineration fly ash - Google Patents

Abstract

The invention discloses a rapid detection method for the stability and toxicity of heavy metals in domestic waste incineration fly ash. The waste fly ash sample to be tested is divided into three parts, and the first part of the fly ash is mixed with water to measure the pH, lead ion, chlorine of the solution. The concentration of ions and calcium ions; the second part of fly ash is mixed with water by adding acetic acid solution to neutrality, and the acid neutralization capacity is measured; Ethanol titration to measure the mass percentage of free calcium oxide in fly ash. Finally, multiple indicators are obtained to comprehensively judge whether the heavy metal stability of fly ash is qualified, that is, whether the leaching toxicity meets the standard. The method solves the problems of long time, low efficiency and difficulty in real-time supervision on site when the current national standard leaching toxicity leaching method is used to judge the stability of heavy metals in the fly ash entering the landfill, and shortens the national standard method that takes more than 18 hours to a time-consuming The comprehensive judgment method of 1 hour can effectively improve the supervision efficiency of heavy metal stability in fly ash.

Description

Rapid detection method of heavy metal stability and toxicity in domestic waste incineration fly ash

technical field

The invention relates to a method for detecting pollution parameters of solid waste, in particular to a method for chemically detecting pollution parameters of domestic waste incineration fly ash, which is applied to the technical field of domestic waste landfill pollution control.

Background technique

The municipal solid waste incineration fly ash is the material collected in the heat recovery and utilization system and the flue gas purification system after the incineration of the domestic solid waste. Among them, there are many harmful substances such as cadmium, lead, zinc, and chromium that can be leached by water. Improper handling will cause heavy metal migration and contaminate groundwater, soil and air. Therefore, waste incineration fly ash is included in the "National Hazardous Waste List", which is a hazardous waste and requires strict supervision and safe disposal. With the continuous growth of urban population and the continuous increase of urban domestic waste, waste incineration is an inevitable choice for the harmless and resourceful disposal of waste.

Fly ash contains a large amount of heavy metal pollutants. The leaching toxicity of the solidified fly ash treated by the mixing and curing process is significantly reduced after entering the landfill. Compared with the uncured fly ash, most of them meet the standard limits, but some Excessive situation. The current methods for detecting the stability of heavy metals in fly ash are the solid waste leaching toxicity leaching method in the Chinese environmental protection industry standard, the sulfuric acid nitric acid method and the acetic acid buffer solution method. However, the detection conditions required by the national standard method are strict, and a variety of professional instruments are required, and it takes a long time, and the inversion processing takes more than 18 hours. Every large fly ash landfill in China needs to receive dozens of batches of fly ash from multiple waste incineration plants in the surrounding area every day. In accordance with the "Standards for Pollution Control of Domestic Waste Landfills", the on-site real-time monitoring of the stability of heavy metals in fly ash entering the landfill will cause some fly ash with incomplete heavy metal stabilization to directly enter the landfill for landfill, causing environmental pollution. hazard. That is to say, the current detection method for the stability of heavy metals in fly ash of municipal solid waste incineration has the shortcomings of long time and low efficiency, which makes it difficult to coordinate the implementation of pretreatment quality and landfill process, and it is difficult to implement the quality control of incoming fly ash. Therefore, it is urgent to find a simpler and more efficient detection method than the national standard method to quickly assess the leaching toxicity of heavy metals in fly ash, so as to achieve effective control of domestic waste landfill pollution.

SUMMARY OF THE INVENTION

In order to solve the problems of the prior art, the object of the present invention is to overcome the deficiencies of the prior art, and to provide a rapid detection method for the stability and toxicity of heavy metals in the incineration fly ash of domestic waste, which can easily and quickly detect the incineration fly ash of domestic waste. The stability of heavy metals provides a solution for the quality control of fly ash entering the landfill site, improves the supervision efficiency of the stability of heavy metals in the fly ash entering the site, and ensures environmental safety.

To achieve the above object, the present invention adopts the following technical solutions:

A rapid detection method for the stability and toxicity of heavy metals in domestic waste incineration fly ash, comprising the following steps:

(1) Provide samples of household waste incineration fly ash to be tested, and divide the provided samples of household waste incineration fly ash to be tested into three parts for use separately;

(2) mixing the first fly ash sample prepared in step (1) with water, stirring for at least 14 minutes to obtain a first mixed solution, and using a pH meter to measure the pH value of the first mixed solution; Add 0.1 ml of nitric acid with a mass percentage concentration of 65 to 68% to the first mixed solution to obtain a first mixed solution test solution, continue to stir the first mixed solution test solution for at least 1 minute, and then use the ion electrode method to measure the first mixed solution. The concentration of each water-soluble ion in the mixed solution test solution is taken as the concentration of each water-soluble ion in the first mixed solution; the water to be mixed with the first fly ash sample is preferably distilled water or deionized water; the stirring method preferably adopts magnetic stirring, electric power Mechanical stirring or manual stirring, preferably control the stirring speed of the first mixed solution to be 150-200r/min; when preparing the first mixed solution, preferably the dosage ratio of the first fly ash sample to water is 0.1g:100ml; When preparing the first mixed solution test solution, preferably the ratio of the amount of nitric acid to the first mixed solution is 0.1ml:100ml; when measuring the concentration of each water-soluble ion in the first mixed solution, the ion electrode preferably used for assembling the electrochemical detection device is: Any one of the lead ion electrode, chloride ion electrode, calcium ion electrode, zinc ion electrode, cadmium ion electrode, chromium ion electrode and copper ion electrode is used alone or any combination of electrodes is used;

(3) mixing the second fly ash sample prepared in step (1) with water, stirring for at least 14 minutes to obtain a second mixed solution, and adding 1 mol/L dropwise to the second mixed solution acetic acid, while monitoring the pH of the second mixed solution, when the second mixed solution becomes neutral, stop adding acetic acid dropwise to the second mixed solution, and record the total amount of acetic acid consumed so far; The water for mixing the ash sample is preferably distilled water or deionized water; the stirring method is preferably magnetic stirring, electric mechanical stirring or manual stirring, and preferably the rotational speed of stirring the second mixed solution is controlled to be 150-200 r/min; When monitoring the pH of the second mixed solution, it is preferable that the second mixed solution becomes neutral, which means that the pH of the second mixed solution is 6.9～100 ml. 7.1;

(4) uniformly mixing the third fly ash sample, strontium nitrate and glycerol dehydrated alcohol prepared in step (1), under constant temperature water bath heating and stirring conditions, stir to obtain the third mixed solution after at least 10 minutes; Then monitor the color change of the third mixed solution, when the third mixed solution is colored, dropwise add the benzoic acid anhydrous ethanol solution with the set ratio to the third mixed solution, until the third mixed solution is added dropwise. The color of the two mixed solutions disappears, record the total consumption of the benzoic acid absolute ethanol solution that has been consumed so far, and measure the third fraction of the benzoic acid absolute ethanol solution according to the titer of the benzoic acid absolute ethanol solution with the set ratio to calcium oxide. The mass percentage of free calcium oxide in the ash sample is the mass percentage of free calcium oxide in the household waste incineration fly ash test sample prepared in step (1); the stirring method preferably adopts magnetic stirring, electric mechanical stirring or manual stirring, preferably The rotational speed of stirring the third mixed solution is controlled to be 150-200 r/min; when preparing the third mixed solution, the preferred dosage ratio of the third fly ash sample, strontium nitrate, and glycerol dehydrated alcohol is 0.5g:1g:30ml; When detecting the amount of free calcium oxide in the third fly ash sample, the preferred heating condition of the constant temperature water bath means that the temperature of the water bath is not higher than 90°C;

(5) In steps (2) to (4), if the following conditions are met at the same time, it can be determined that the heavy metals in the sample of domestic waste incineration fly ash to be tested prepared in step (1) have good stability, and the leaching toxicity will basically not exceed the standard :

In step (2), the pH value of the first mixed solution is measured to be 11.5 to 12.3, and the ion electrode method is used to measure the water-soluble lead ion concentration in the first mixed solution is not higher than 0.000058mol/L, and the first mixed solution is measured The water-soluble chloride ion concentration in the mixed solution is not higher than 0.02 mol/L, and the measured water-soluble calcium ion concentration in the first mixed solution is 0.000008-0.003 mol/L;

In step (3), the total amount of acetic acid consumed by adding dropwise acetic acid to the second mixture is 5ml～9ml;

In step (4), the mass percentage of free calcium oxide in the third fly ash sample is measured to be 10-18%.

As a preferred technical solution of the present invention, in step (4), when measuring the mass percent of free calcium oxide in the third fly ash sample, the details are as follows:

First observe the color of the prepared third mixed solution, if the third mixed solution is reddish, then dropwise add the benzoic acid anhydrous ethanol solution with the set ratio to the third mixed solution, until The reddish color of the third mixed solution disappeared;

After repeating the stirring of the third mixed solution for at least 10 minutes, continue to monitor the color change of the third mixed solution. If the third mixed solution does not change to a reddish color, record the benzoic acid anhydrous ethanol solution accumulated so far. Total dosage, and compare the titer of benzoic acid anhydrous ethanol solution to calcium oxide, calculate the mass percentage of free calcium oxide in the third fly ash sample; if the third mixed solution turns reddish again, continue to the third The benzoic acid anhydrous ethanol solution with the set ratio is added dropwise to the mixed solution, until the reddish color of the third mixed solution disappears, and the total consumption of the benzoic acid anhydrous ethanol solution so far is recorded. Calculate the mass percentage of free calcium oxide in the third fly ash sample by comparing the titer of calcium oxide with anhydrous ethanol solution of benzoic acid.

As a preferred technical solution of the present invention, before measuring the concentration of each water-soluble ion in the first mixed solution in step (2), respectively prepare a chloride ion standard solution, a calcium ion standard solution and a lead ion standard solution with a series of chloride ion concentrations , and prepare a saturated potassium nitrate solution with potassium nitrate; then, the chloride ion electrode is placed in one of the chloride ion standard solutions for activation, the calcium ion electrode is placed in one of the calcium ion standard solutions for activation, and the lead ion electrode is placed in one of the calcium ion standard solutions for activation. One of the lead ion standard solutions was activated, and the reference electrode was placed in a saturated potassium nitrate solution for activation; then electrochemical detection devices were assembled respectively, and the chloride ion electrode and the reference electrode were used to measure the potential of each chloride ion standard solution, Draw the standard curve of chloride ion concentration and potential, use calcium ion electrode and reference electrode to measure the potential of each calcium ion standard solution, draw the standard curve of calcium ion concentration and potential, use lead ion electrode and reference electrode to measure each lead ion standard The potential of the solution, the standard curve of the lead ion concentration and the potential is drawn; when measuring the concentration of each water-soluble ion in the first mixed solution in step (2), an electrochemical measuring device is assembled, and the lead ion electrode, chloride ion electrode, calcium ion The electrodes are put into the first mixed solution test solution with the reference electrode respectively, and the displayed potential is recorded respectively, and the potential is converted into the water-soluble lead ion concentration in the first mixed solution test solution according to the standard curve of the above-mentioned ion concentration and potential. , water-soluble chloride ion concentration, water-soluble calcium ion concentration, as the water-soluble ion concentration in the first mixed solution.

Compared with the prior art, the present invention has the following obvious outstanding substantive features and significant advantages:

1. The present invention solves the problems of long time, low efficiency, and difficulty in real-time supervision on site when judging the stability of heavy metals in landfill entry fly ash using the national standard leaching toxicity leaching method, and shortens the national standard method that takes more than 18 hours. It is a comprehensive judgment method that takes less than 1 hour, which can effectively improve the supervision efficiency of the heavy metal stability of the admission fly ash;

2. The method of the present invention is simple, has a good detection effect, is simpler and more efficient than the national standard method, can quickly evaluate the heavy metals and leaching toxicity of the fly ash entering the site, is suitable for the harmless and resourceful treatment of fly ash from various household waste incineration, and can frame Effectively realize the safe management of hazardous waste and ensure environmental safety.

Detailed ways

Preferred embodiments of the present invention are described in detail as follows:

Example 1:

In the present embodiment, a rapid detection method for the stability and toxicity of heavy metals in domestic waste incineration fly ash includes the following steps:

a. Provide samples of domestic waste incineration fly ash to be tested; divide the provided samples of domestic waste incineration fly ash to be tested into three parts for use separately; use sodium chloride to configure chloride ion concentrations of 10 ^-1 mol/L, 10 ^-2 mol/L, 10 ^-3 mol/L, 10 ^-4 mol/L, 10 ^-5 mol/L of chloride ion standard solution, calcium chloride was used to prepare calcium ion concentrations of 10 ^-1 mol/L, 10 ^-2 mol/L, 10 ^{- 3} mol/L, 10 ^-4 mol/L, 10 ^-5 mol/L calcium ion standard solution, and lead nitrate was used to prepare lead ion concentrations of 10 ^-1 mol/L, 10 ^{- 2} mol/L, 10 ^-3 mol/L, 10 ^-4 mol/L, 10 ^-5 mol/L lead ion standard solution, use potassium nitrate to configure saturated potassium nitrate solution;

b. the chloride ion electrode is placed in the chloride ion standard solution of 10 ^-3 mol/L in the above-mentioned steps a and activated for 2 hours, and the calcium ion electrode is placed in the calcium ion standard solution of 10 ^-3 mol/L in the above-mentioned steps a. Activated for 2 hours, the lead ion electrode was placed in the lead ion standard solution of 10 ^-3 mol/L in the above-mentioned steps a, and activated for 2 hours, and the 217-type reference electrode was placed in the above-mentioned steps a. The saturated potassium nitrate solution was activated for 2 hours ;

c. Use chloride ion electrode and reference electrode to measure the potential of each chloride ion standard solution, draw the standard curve of chloride ion concentration and potential, use calcium ion electrode and reference electrode to measure the potential of each calcium ion standard solution, and draw calcium ion concentration Standard curve with potential, use lead ion electrode and reference electrode to measure the potential of each lead ion standard solution, draw the standard curve of lead ion concentration and potential;

d. Mix the first fly ash sample prepared in step a with water, that is, place 0.1 g of fly ash and 100 ml of distilled water in a beaker, place the beaker on a magnetic stirrer, and add a C40 type polymer to the beaker. The tetrafluoro stirrer adopts magnetic stirring, and the rotational speed of the stirrer is controlled to be 150-200 r/min, and the stirring is carried out for 14 min to obtain the first mixed solution;

e. Using a pH meter, put the pH electrode into the first mixed solution obtained in the above step d, slowly agitate the pH electrode until the reading on the pH meter is stable, and record the pH value of the solution; the pH meter used requires the accuracy of PTS In 97～100%;

f. adding 0.1 ml of nitric acid with a mass percentage concentration of 65% to the solution obtained in the above step d, using magnetic stirring, controlling the rotational speed of the stirring bar to be 150 to 200 r/min, and continuing to stir for 1 min to obtain the first mixed solution test solution;

g. adopt the ion electrode method, put the lead ion electrode, chloride ion electrode and calcium ion electrode that are activated in the above step b into the first mixed solution test solution obtained in the above step f with the reference electrode respectively, and record the displayed Potential, according to the standard curve in the above-mentioned steps c, the potential is converted into water-soluble lead ion concentration, chloride ion concentration, calcium ion concentration in the first mixed solution test solution, as each water-soluble ion concentration in the first mixed solution;

h. Mix the second fly ash sample prepared in step a with water, that is, place 1 g of fly ash and 100 ml of distilled water in a beaker, use magnetic stirring, place the beaker on a magnetic stirrer, and add one tablet to the beaker C40 type polytetrafluoro stirrer, control the rotational speed of the stirrer to be 150-200r/min, and stir for 14min to obtain the second mixed solution;

i. Put the pH electrode into the second mixed solution obtained in the above step h, slowly stir the pH electrode, add 1 mol/L acetic acid solution dropwise to the solution simultaneously, and monitor the pH of the second mixed solution until the pH meter displays the second When the mixture just becomes neutral, stop adding acetic acid dropwise to the second mixture, and record the total amount of acetic acid consumed so far; in this embodiment, the mixture just becomes neutral means that the pH meter reading is 6.90～7.10;

j. Take 0.5g of the third fly ash sample prepared in step a, that is, place 0.5g fly ash sample, 30ml of glycerol absolute ethanol and 1g of strontium nitrate in a 250ml conical flask, and mix them evenly. The flask is connected to a condenser tube, and the conical flask is placed on a water bath constant temperature magnetic stirrer. When stirring, a C40 type polytetrafluoro stirrer is used, and the rotational speed of the stirrer is controlled to be 150-200 r/min. Under the condition of constant temperature water bath heating and stirring, after stirring for 10 minutes, the third mixed solution was obtained;

K. monitor the color change situation of the third mixed solution obtained in above-mentioned steps j, observe the color of the third mixed solution, find that the third mixed solution becomes reddish now, then titrate to the reddish disappearance with benzoic acid absolute ethanol solution , and then repeat the water bath constant temperature stirring step in the above step j, and after stirring the third mixed solution for at least 10 minutes, continue to monitor the color change of the third mixed solution; at this time, the third mixed solution turns reddish again, then continue In the third mixed solution, add dropwise the benzoic acid anhydrous ethanol solution with the set ratio, until the reddish color of the third mixed solution disappears, and record the benzoic acid anhydrous consumed so far. The total consumption of ethanol solution, and the titer of calcium oxide of benzoic acid anhydrous ethanol solution is compared, and the mass percentage of free calcium oxide in the third fly ash sample is calculated, which is the domestic waste incineration fly ash prepared in step a. Measure the mass percentage of free calcium oxide in the sample;

l. In steps e, g, i and k, if the following conditions are met at the same time, it can be determined that the stability of the heavy metals in the sample of domestic waste incineration fly ash to be tested prepared in step a is good, and the leaching toxicity will basically not exceed the standard:

(i) in step e, the pH value of the measured first mixed solution is 11.5～12.3;

(ii) in step g, the ion electrode method is used to measure the water-soluble lead ion concentration in the first mixed solution not higher than 0.000058mol/L, and the measured water-soluble chloride ion concentration in the first mixed solution is not higher than 0.02 mol/L, the water-soluble calcium ion concentration in the first mixed solution is measured to be 0.000008 to 0.003 mol/L;

(iii) in step i, the total amount of acetic acid consumed by adding dropwise acetic acid to the second mixture is 5ml～9ml;

(iv) In step k, the mass percentage of free calcium oxide in the third fly ash sample is measured to be 10-18%.

This example proposes for the first time the use of rapid stirring solution pH measurement method, water-soluble lead ion concentration measurement method, water-soluble chloride ion concentration measurement method, water-soluble calcium ion concentration measurement method, acid neutralization capacity measurement method, and free calcium oxide content measurement method. These six methods are used to comprehensively judge whether the heavy metal stability of the fly ash is qualified, that is, whether the leaching toxicity meets the standard. This set of methods has important guiding significance for fly ash landfill entry supervision, and can effectively improve the efficiency of fly ash leaching toxicity supervision. The national standard leaching toxicity leaching method that takes more than 18 hours is shortened to a comprehensive judgment method that takes only 1 hour, which can easily and quickly detect fly ash samples with excessive leaching toxicity, and improve the quality control of fly ash landfills. The work efficiency can be timely fed back to the daily operation data, and the pretreatment quality and landfill process can be coordinated. The method of this embodiment has convenient operability and good practical application benefits. Finally, the six indicators obtained are used to comprehensively judge whether the heavy metal stability of domestic waste incineration fly ash is qualified, that is, whether the leaching toxicity meets the standard. This embodiment solves the problems of long time, low efficiency, and difficulty in on-site real-time supervision when using the national standard leaching toxicity leaching method to judge the stability of heavy metals in the fly ash entering the landfill site, and can effectively improve the stability of the heavy metals in the fly ash entering the site. regulatory efficiency.

Embodiment 2:

This embodiment is basically the same as the first embodiment, and the special features are:

In this embodiment, experimental testing and verification analysis are carried out on each part of the samples prepared in the embodiment. A rapid test method for heavy metal stability and toxicity, with a detailed description of prominent substantive features and significant advances:

Taking the chelated and stabilized domestic waste incineration fly ash produced by Shanghai Laogang Incineration Plant on December 23, 2016 as an example, the Pb content in the fly ash sample selected here accounts for 3‰ of the total mass of fly ash, and then the Adding 1‰, 2‰ and 3‰ of lead, a total of four ash samples were prepared, numbered ①, ②, ③, ④, and their lead contents were 3‰, 4‰, 5‰ and 6‰, respectively.

Four samples were tested using each rapid detection method and the results were as follows:

Rapid stirring solution pH determination:

It can be seen from the data of the pH of the rapidly stirred solution that the measured data of the four gray samples are the same, which are all 11.51. According to the provisions of the index standard in step 1 of Example 1, the samples with good stability of heavy metals and those whose toxicity does not exceed the standard should meet the requirements of The following conditions:

After rapid stirring, the pH value of the mixture is 11.5-12.3. Therefore, the four gray samples were all identified as the leaching toxicity of heavy metals that would not exceed the standard.

Determination of water-soluble calcium ion concentration:

From the data of the water-soluble calcium ion concentration determination method, it can be seen that the measured data of the four gray samples are basically the same, all close to 0.001mol/L. According to the provisions of the index standard in Example 1, the heavy metal has good stability and toxicity. The sample should meet the following conditions: the measured water-soluble calcium ion concentration is 0.000008mol/L～0.003mol/L. Therefore, the four gray samples were all identified as the leaching toxicity of heavy metals that would not exceed the standard.

Water-soluble chloride ion concentration determination method:

From the data of the water-soluble chloride ion concentration determination method, it can be seen that the measured data of the four gray samples are basically the same, which are all close to 0.005mol/L. According to the provisions of the index standard in the present invention, the samples with good heavy metal stability should meet the following requirements Conditions: The measured water-soluble chloride ion concentration is 0 mol/L to 0.02 mol/L. Therefore, the four gray samples were all identified as the leaching toxicity of heavy metals that would not exceed the standard.

Water-soluble lead ion concentration determination method:

From the data of the water-soluble lead ion concentration determination method, it can be seen that the measured data of the four gray samples are quite different. The following conditions: the measured water-soluble lead ion concentration does not exceed 0.000058mol/L. The samples of No. 1 and No. 2 were identified as the leaching toxicity that basically did not exceed the standard. The concentrations of water-soluble lead ions measured for samples ③ and ④ were not within the specified safe range, so they were identified as leaching toxicity that was likely to exceed the standard.

Acid neutralization capacity assay:

It can be seen from the data of the acid neutralization capacity determination method that the measured data of the four ash samples are basically the same, and they are all close to 6.3ml. The sample should meet the following conditions: the total amount of acetic acid consumed is 5-9ml. Therefore, the four gray samples were identified as the leaching toxicity that basically did not exceed the standard.

Determination of free calcium oxide content:

It can be seen from the data of the free calcium oxide determination method that the measured data of the four ash samples are basically the same, and they are all close to 10.9%. According to the provisions of the index standard in the present invention, the samples with good heavy metal stability should meet the following conditions: fly ash The mass percentage of free calcium oxide in the medium is 10% to 18%. Therefore, the four gray samples were identified as the leaching toxicity that basically did not exceed the standard.

Considering the results of the above six rapid detection methods, it can be inferred that the leaching toxicity of samples No. 1 and No. 2 will basically not exceed the standard, and samples No. 3 and No. 4 are beyond the safe range due to the high content of water-soluble lead ions. Therefore, the leaching toxicity of heavy metals in samples ③ and ④ is likely to exceed the standard.

The results verified using the national standard leaching toxicity leaching method are as follows:

From the data of the above national standard method, it can be seen that the leaching amount of Pb in samples No. 1 and No. 2 is less than the standard limit of 5 mg/L, so their leaching toxicity is up to the standard; while the leaching amount of Pb in samples No. 3 and No. 4 is greater than The standard limit is 5mg/L, so their leaching toxicity exceeds the standard.

Comparing the results obtained by the six rapid detection methods with the results of the national standard method, it can be seen that the six rapid detection methods are used to comprehensively conclude that the leaching toxicity of No. 1 and No. 2 samples will basically not exceed the standard, and No. The leaching toxicity exceeds the standard; the results measured by the national standard method are that the leaching toxicity of No. 1 and No. 2 samples meets the standard, and the leaching toxicity of No. 3 and No. 4 samples exceeds the standard. Both reached the same conclusion. Therefore, in practical application, the method of Embodiment 1 is practical and effective.

Embodiment three:

This embodiment is basically the same as the first embodiment, and the special features are:

In the present embodiment, a rapid detection method for the stability and toxicity of heavy metals in domestic waste incineration fly ash includes the following steps:

a. This step is the same as the first embodiment;

b this step is the same as the first embodiment;

c. this step is identical with embodiment one;

d. this step is identical with embodiment one;

e. this step is identical with embodiment one;

f. adding 0.1 ml of nitric acid with a mass percentage concentration of 68% to the solution obtained in the above step d, using magnetic stirring, controlling the rotational speed of the stirring bar to be 150 to 200 r/min, and continuing to stir for 1 min to obtain the first mixed solution test solution;

g. this step is identical with embodiment one;

h. This step is the same as that of Embodiment 1;

i. This step is the same as that of Embodiment 1;

j. This step is the same as the first embodiment;

K. monitor the color change situation of the third mixed solution obtained in above-mentioned steps j, observe the color of the third mixed solution, find that the third mixed solution becomes reddish now, then titrate to the reddish disappearance with benzoic acid absolute ethanol solution , and then repeat the water bath constant temperature stirring step in the above step j, and after stirring the third mixed solution for at least 10 minutes, continue to monitor the color change of the third mixed solution; at this time, the third mixed solution does not turn reddish, then record the The total consumption of benzoic acid absolute ethanol solution that has been accumulated so far, and the titer of benzoic acid absolute ethanol solution to calcium oxide is compared, and the mass percentage of free calcium oxide in the third fly ash sample is calculated, that is, in step The mass percentage of free calcium oxide in the sample of domestic waste incineration fly ash to be tested prepared in a;

l. This step is the same as the first embodiment.

In this embodiment, the rapid detection method for the stability and toxicity of heavy metals in domestic waste incineration fly ash includes the following steps: dividing the provided samples of domestic waste incineration fly ash to be tested into 3 parts, and mixing the first fly ash with water After stirring, measure the pH of the solution, the concentration of water-soluble lead ions, the concentration of water-soluble chloride ions, and the concentration of water-soluble calcium ions in the solution; after the second fly ash is mixed with water, the acetic acid solution is added dropwise to neutrality, and the acid neutralization is measured. capacity; the third fly ash is mixed with strontium nitrate and glycerol absolute ethanol, and the mass percentage of free calcium oxide in the fly ash is measured by titration with benzoic acid absolute ethanol. Finally, the six indicators obtained are used to comprehensively judge whether the heavy metal stability of domestic waste incineration fly ash is qualified, that is, whether the leaching toxicity meets the standard. This embodiment also solves the problems of long time, low efficiency, and difficulty in on-site real-time supervision when using the national standard leaching toxicity leaching method to judge the stability of heavy metals in the fly ash entering the landfill site, and shortens the national standard method that takes more than 18 hours. It is a comprehensive judgment method that takes less than 1 hour, which can effectively improve the supervision efficiency of the heavy metal stability of the admission fly ash.

The embodiments of the present invention have been described above, but the present invention is not limited to the above-mentioned embodiments, and various changes can also be made according to the purpose of the invention and creation of the present invention. Modification, substitution, combination or simplification should all be equivalent substitution methods, as long as the purpose of the invention is met, as long as it does not deviate from the technical principle and invention of the rapid detection method for the stability and toxicity of heavy metals in domestic waste incineration fly ash of the present invention All ideas belong to the protection scope of the present invention.

Claims (7)

1. A method for rapidly detecting the stability and toxicity of heavy metals in household garbage incineration fly ash is characterized by comprising the following steps:

(1) providing a sample to be tested of the household garbage incineration fly ash, and dividing the provided sample to be tested of the household garbage incineration fly ash into three parts for later use respectively;

(2) mixing the first part of fly ash sample prepared in the step (1) with water, stirring for at least 14 minutes to obtain a first mixed solution, and measuring the pH value of the first mixed solution by using a pH meter; then adding 0.1ml of nitric acid with the mass percentage concentration of 65-68% into the first mixed solution to obtain a first mixed solution test solution, continuously stirring the first mixed solution test solution for at least 1 minute, and measuring the concentration of each water-soluble ion in the first mixed solution test solution by adopting an ion electrode method to obtain the concentration of each water-soluble ion in the first mixed solution as the concentration of each water-soluble ion in the first mixed solution;

(3) mixing the second part of fly ash sample prepared in the step (1) with water, stirring for at least 14 minutes to obtain a second mixed solution, dropwise adding 1mol/L of acetic acid into the second mixed solution while monitoring the pH of the second mixed solution, stopping dropwise adding the acetic acid into the second mixed solution when the second mixed solution becomes neutral, and recording the total amount of acetic acid consumed up to this point;

(4) uniformly mixing the third fly ash sample prepared in the step (1), strontium nitrate and glycerol absolute ethyl alcohol, and stirring for at least 10 minutes under the conditions of constant-temperature water bath heating and stirring to obtain a third mixed solution; then monitoring the color change condition of the third mixed solution, when the third mixed solution is colored, dropwise adding a benzoic acid absolute ethyl alcohol solution with a set ratio into the third mixed solution until the color of the second mixed solution disappears, recording the total consumption of the benzoic acid absolute ethyl alcohol solution accumulated till now, and measuring the mass percentage of free calcium oxide in the third fly ash sample according to the titer of the benzoic acid absolute ethyl alcohol solution with the set ratio on calcium oxide to obtain the mass percentage of the free calcium oxide in the household garbage incineration fly ash sample to be detected, which is the mass percentage of the free calcium oxide in the household garbage incineration fly ash sample to be detected prepared in the step (1);

(5) in the steps (2) to (4), if the following conditions are met, it can be determined that the stability of the heavy metals in the sample to be tested of the municipal solid waste incineration fly ash prepared in the step (1) is good, and the leaching toxicity basically does not exceed the standard:

in the step (2), the pH value of the first mixed solution is measured to be 11.5-12.3, an ion electrode method is adopted, the concentration of water-soluble lead ions in the first mixed solution is measured to be not higher than 0.000058mol/L, the concentration of water-soluble chloride ions in the first mixed solution is measured to be not higher than 0.02mol/L, and the concentration of water-soluble calcium ions in the first mixed solution is measured to be 0.000008-0.003 mol/L;

in the step (2), when preparing the first mixed solution, the ratio of the first part of fly ash sample to water is 0.1 g: 100 ml; when preparing the first mixed solution test solution, the ratio of the amount of the nitric acid to the amount of the first mixed solution is 0.1 ml: 100 ml;

in the step (3), 5ml to 9ml of acetic acid total amount consumed in the second mixed solution is dropwise added;

in the step (3), when preparing the second mixed solution, the usage ratio of the second fly ash sample to water is 1 g: 100 ml;

in the step (4), the mass percent of free calcium oxide in the third fly ash sample is 10-18%;

in the step (4), when a third mixed solution is prepared, the dosage ratio of the third fly ash sample, strontium nitrate and glycerol absolute ethyl alcohol is 0.5 g: 1 g: 30 ml.

2. The method for rapidly detecting the stability and toxicity of the heavy metals in the fly ash generated by incinerating the household garbage according to claim 1, which is characterized in that: in the step (2) and the step (3), distilled water or deionized water is adopted as water to be mixed with the first fly ash sample and the second fly ash sample respectively; in the steps (2) to (4), the stirring method adopts magnetic stirring, electromechanical stirring or manual stirring, and the stirring speed of the first mixed solution, the second mixed solution or the third mixed solution is controlled to be 150 to 200 r/min.

3. The method for rapidly detecting the stability and toxicity of the heavy metals in the fly ash generated by incinerating the household garbage according to claim 1, which is characterized in that: in the step (2), when the concentration of each water-soluble ion in the first mixed solution is measured, the ionic electrode used for assembling the electrochemical detection device is any one of a lead ion electrode, a chloride ion electrode, a calcium ion electrode, a zinc ion electrode, a cadmium ion electrode, a chromium ion electrode and a copper ion electrode, which is used alone or in combination.

4. The method for rapidly detecting the stability and toxicity of the heavy metals in the fly ash generated by incinerating the household garbage according to claim 1, which is characterized in that: in the step (3), when the pH of the second mixed solution is monitored, the second mixed solution becomes neutral, which means that the pH of the second mixed solution is 6.9 to 7.1.

5. The method for rapidly detecting the stability and toxicity of the heavy metals in the fly ash generated by incinerating the household garbage according to claim 1, which is characterized in that: in the step (4), when the amount of free calcium oxide in the third fly ash sample is detected, the constant-temperature water bath heating condition is that the water bath temperature is not higher than 90 ℃.

6. The method for rapidly detecting the stability and toxicity of the heavy metals in the fly ash generated by incinerating the household garbage according to claim 1, which is characterized in that:

in the step (4), when the mass percentage of free calcium oxide in the third fly ash sample is measured, firstly, observing the color of the prepared third mixed solution, and if the third mixed solution is reddish, dropwise adding a benzoic acid absolute ethyl alcohol solution with a set ratio into the third mixed solution in a dropwise adding mode until the reddish color of the third mixed solution disappears;

repeatedly stirring the third mixed solution for at least 10 minutes, continuously monitoring the color change condition of the third mixed solution, if the third mixed solution does not turn reddish, recording the total consumption of the benzoic acid absolute ethyl alcohol solution which is consumed up to now, comparing the titer of the benzoic acid absolute ethyl alcohol solution on calcium oxide, and calculating the mass percentage of free calcium oxide in the third fly ash sample; and if the third mixed solution turns reddish again, continuously dropwise adding the benzoic acid absolute ethyl alcohol solution with the set proportion into the third mixed solution in a dropwise adding mode until the reddish color of the third mixed solution disappears, recording the total consumption of the benzoic acid absolute ethyl alcohol solution until the reddish color of the third mixed solution disappears, and calculating the mass percent of free calcium oxide in the third fly ash sample by comparing the titer of the benzoic acid absolute ethyl alcohol solution to calcium oxide.

7. The method for rapidly detecting the stability and toxicity of the heavy metals in the fly ash generated by incinerating the household garbage according to claim 1, which is characterized in that: before measuring the concentration of each water-soluble ion in the first mixed solution in the step (2), preparing a chloride ion standard solution, a calcium ion standard solution and a lead ion standard solution with a series of chloride ion concentrations, and preparing a saturated potassium nitrate solution by using potassium nitrate; then, placing the chloride ion electrode in one of the chloride ion standard solutions for activation, placing the calcium ion electrode in one of the calcium ion standard solutions for activation, placing the lead ion electrode in one of the lead ion standard solutions for activation, and placing the reference electrode in a saturated potassium nitrate solution for activation; then respectively assembling electrochemical detection devices, measuring the potential of each chloride ion standard solution by using a chloride ion electrode and a reference electrode, drawing a standard curve of the concentration and the potential of the chloride ions, measuring the potential of each calcium ion standard solution by using a calcium ion electrode and a reference electrode, drawing a standard curve of the concentration and the potential of the calcium ions, measuring the potential of each lead ion standard solution by using a lead ion electrode and a reference electrode, and drawing a standard curve of the concentration and the potential of the lead ions; when the concentration of each water-soluble ion in the first mixed solution is measured in the step (2), an electrochemical measuring device is assembled, the lead ion electrode, the chloride ion electrode and the calcium ion electrode are respectively placed into the first mixed solution test solution together with the reference electrode, displayed potentials are respectively recorded, and the potentials are converted into the concentration of each water-soluble lead ion, the concentration of each water-soluble chloride ion and the concentration of each water-soluble calcium ion in the first mixed solution test solution according to the standard curve of each ion concentration and the potential to be used as the concentration of each water-soluble ion in the first mixed solution.