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1. Analysis of arsenic in drinking water
2. Analysis of the determination method of arsenic content in atomic fluorescence spectrometer
4 Conclusion
Discussion on Determination Method of Arsenic Content in Drinking Water
Abstract: In recent years, there have been very frequent incidents of arsenic poisoning in domestic water. These poisoning incidents involve a wide population, a very serious condition, and complicated wards. In China, the arsenic hazard in domestic water has become a health problem that is urgently needed to be solved. In the article, the method of determining the arsenic content in domestic water by atomic fluorescence spectrometer is analyzed. The coagulation method and adsorption method are analyzed in detail.
Key words: drinking water; arsenic; determination method; atomic fluorescence spectrometer; coagulation method; adsorption method
Generally speaking, arsenic is a protoplasmic poison and is a carcinogen and should be given priority control. The diagnosis of arsenic poisoning patients and the determination of high arsenic areas have now become local prevention and control work in China. For early diagnosis, the determination of arsenic content in drinking water has a very important role, especially the accurate determination of high arsenic area and the correct diagnosis of patients have very significant effects.
As we all know, drinking water is an indispensable part of human survival and plays a very important role in daily life. Therefore, the health of drinking water should be effectively guaranteed. Arsenic is an element that needs to be monitored in drinking water. It is a key indicator and is an element that can accumulate other toxic elements. Due to the high toxicity of arsenic compounds, it is a heavy metal monitoring test in drinking water. In China, relevant standards have been promulgated to effectively ensure the safety of residents and the health of the body. In the relevant tests, many test methods are introduced in detail.
2.1 Analysis of the principle of atomic fluorescence photometer
In an acidic environment, after the potassium arsenic encounters potassium hydride, a certain chemical reaction occurs, and then arsine is synthesized. Hydrogen is added to the quartz to decompose the arsine into atomic arsenic. If the cathode lamp encounters hydrogen arsenide, the atomic state arsenic will become a high energy state, and when it returns to the ground state, it will emit fluorescence and be detected. The arsenic content is proportional to the fluorescence intensity, so the arsenic content can be measured using an atomic fluorescence spectrometer.
2.2 Analytical reagents and standard solutions
First, the standard stock solution of arsenic is 1000 micrograms per milliliter, and 1% sulfur- 1% ascorbic acid-5% nitric acid mixture is also required. The mixture is prepared by adding 25 ml of nitric acid to 200 ml of distilled water. At the same time, add 5 grams of sulfur and ascorbic acid, and dilute to 500 ml to ensure the current use. At the same time, 1.5% potassium borohydride-0.2% sodium hydroxide is needed. The main method is to dissolve 1 gram of sodium hydroxide in 200 ml of distilled water, then dissolve 7 gram of potassium borohydride and dilute to 500. The milliliters also need to be used now. 3% nitric acid carrier solution, which requires adding 15 ml of concentrated nitric acid to 300 ml of distilled water and diluting to 500 ml.
The standard arsenic solution is prepared by dissolving 1 ml of arsenic stock solution in a 100 ml volumetric flask, then adding 3% nitric acid, then diluting to the specified concentration and mixing uniformly.
2.3 Analysis of atomic fluorescence spectrophotometer
(1) The specific conditions for the operation of the instrument. The optimum conditions for specific atomic fluorescence operating conditions are shown in Table 1.
Table 1 The best working conditions of the atomic fluorescence photometer
Project name best condition
Atomic furnace temperature 300 degrees Celsius
Carrier gas 100-200 ml per minute
Shielding gas 400-600 ml per minute
Lamp main current 90 mA
Lamp shaft current 50 mA
Negative high voltage 300-360 volts
(2. Determination of the sample. Generally, 10 ml of water sample is taken up in the sample tube to dissolve, then 1 ml of hydrochloric acid is added, and the mixture is uniformly mixed, and 15 ml of the solution is added before the test. Tested 8 times to ensure the precision of the test.
(3) Analysis considerations. In the actual process, in order to effectively prevent the occurrence of pollution, the glassware should be rinsed with dilute nitric acid, and there are specific capacity bottles. The previous sample to be tested should be soaked with a sulfur-ascorbic acid solution, and about 15 ml of the solution should be placed before the test. If there is a relatively low temperature
When less than 15 degrees Celsius, 15 ml of solution should be placed to be tested. 2.4 Analysis results
First, the water sample is measured. Add 20 ml of water sample to be tested in a 50 ml colorimetric tube, then add 2.5 g of concentrated nitric acid, mix evenly, and wait for 20 minutes. In the autosampler, add water sample and standard solution, set the corresponding parameters and then preheat.
Then, select the condition. The choice of equal current for arsenic in drinking water is very important. In the specific experiment, the arsenic lamp current should be selected to be 60 mA, which meets the experimental needs and effectively extends the service life.
3. Analysis of methods for removing arsenic from drinking water 3.1 Analysis of coagulation
In the process of treating domestic drinking water and industrial water, coagulation is the most widely used method for removing arsenic. It can effectively ensure that drinking water meets the corresponding standards, and can also ensure that industrial wastewater meets certain requirements. The most common type of coagulant, including polysilicate iron. Related studies have shown that iron salts have a better arsenic removal effect than aluminum salts.
In the actual process of removing arsenic, the removal effect of arsenic (V) is more effective than that of arsenic (I). Therefore, arsenic should be pre-oxidized, and then coagulation treatment should be added to increase the catalyst to effectively ensure oxidation, thereby effectively increasing oxidation. Effect.
Using orthogonal test to observe the influence of various factors such as coagulant and coagulant on the effect of arsenic removal, it is obvious that the effect of removing arsenic by using only ferric sulfate is the best, and adding activated carbon in arsenic removal water will not be obtained. Very good effect, however, the adoption of filtration measures significantly improved the arsenic removal effect, indicating that the product produced by the hydrolysis of the coagulant will adsorb arsenic. When the iron ion has a relatively high pH value, it will produce a lot. The colloid has a very high adsorption capacity. After some experiments, it is shown that after the addition of the coagulant, the previously dissolved arsenic will become a state of insolubilization, thereby achieving the purpose of removing arsenic.
In general, the use of coagulation method will produce a lot of arsenic-containing waste residue, which cannot be reused at all. In addition, a lot of coagulant is needed in actual operation, and long-term accumulation will cause secondary pollution, which is very Difficult handling, which limits the practical application of coagulation to remove arsenic to some extent.
3.2 Analytical adsorption method
This method is generally suitable for a water treatment system with a relatively low concentration and a relatively large amount of treatment, and is a very simple technique. The adsorbent of the adsorption method is a solid material which is insoluble and has a very high surface area and is fixed on the surface, thereby achieving the effect of removing arsenic. There are many adsorbents for arsenic removal, including activated alumina, zeolite, metal oxides and activated carbon.
According to the results of atomic fluorescence spectrophotometry, it can be clearly seen that the method for measuring arsenic contained in drinking water is very simple, has a very simple detection process, and has very good reproducibility and is relatively low. Detection limit. Under relatively normal conditions, the arsenic content contained in tap water and raw water is relatively low. Therefore, in the determination of arsenic in water, a relatively ideal method is the atomic fluorescence spectrometer method.