Detection method of thermal spring water

Abstract

The invention belongs to the field of water quality detection, and relates to a thermal spring water detection method, which is used for determining 11 primary and secondary elements of potassium, sodium, calcium, magnesium, silicon, boron, lithium, strontium, arsenic, iron, chlorine and sulfate radicals in geothermal water, and adopts an inductively coupled plasma emission spectrometer, a cross atomizer and an axial and radial bidirectional observation mode. The invention solves the problem of determination of trace elements in geothermal water with higher salinity, and establishes a method for directly determining multiple elements in geothermal water by adopting an ICP-MS (Inductively Coupled Plasma Mass Spectrometry) method. Experimental results show that the method is efficient, reliable and easy and convenient to operate, the pretreatment process of the sample is simplified, the measurement result is matched with that of a traditional testing method, and the method has the advantages of being low in detection limit, good in precision, high in adding standard recovery rate and the like.

Description

Technical Field

[0001] The invention belongs to the field of water quality detection, in particular to a method for detecting hot spring water. Background Art

[0002] Geothermal springs are a special type of mineral resource. They are not only used for power generation, but are also widely used in health care, agriculture, breeding, heating, entertainment and tourism. From the formation and characteristics of geothermal springs, it is different from mineral springs in the general sense. It is an underground hot spring whose mineral components meet the relevant indicators. It is different from drinking water and daily drinking mineral water in terms of mineral components and water quality characteristics. Therefore, the analysis and testing of geothermal mineral spring samples cannot simply adopt some relevant exploration specifications and inspection methods of existing drinking natural mineral water (GB / T 8538-2008, GB8537-2008, GB / T 5009.167-2003, GB / T 13727-1992), relevant specifications and analysis methods for drinking water (CJ3020-1993, GB 5749-2006, GB 5749-2006GB / T 5750.1~5750.13-2006) and groundwater analysis methods (GB / T 14848-1993, SL 454-2010, HJ / T 164-2004, DZ / T 0133-1995, DZ / T 0064.1~80-1993), the temperature and high mineralization should be strictly considered in the analysis of geothermal mineral water. At present, the determination of various elements in geothermal water samples is mostly done by flame atomic absorption spectrometry, ion chromatography and spectrophotometry. The main disadvantage of these methods is that one sample solution cannot be used to determine multiple elements at the same time, and the operation is complicated and time-consuming. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for detecting hot spring water that can simultaneously detect and analyze multiple elements.

[0004] The technical solution adopted by the present invention to solve the technical problem is:

[0005] A method for detecting hot spring water is used to determine 11 major and minor elements, potassium, sodium, calcium, magnesium, silicon, boron, lithium, strontium, arsenic, iron, chlorine and sulfate, in geothermal water using an inductively coupled plasma emission spectrometer, a cross atomizer, and an axial and radial two-way observation mode.

[0006] Furthermore, the power of the inductively coupled plasma emission spectrometer was set to 1300 W, the auxiliary gas flow rate was 0.2 L / min, the nebulizer flow rate was 0.67 L / min, the plasma flow rate was 15 L / min, the nebulizer pressure was 105 KPa, the injection volume was 1.5 mL / min, and the integration time was 2 to 10 s.

[0007] Furthermore, 5% hydrochloric acid or nitric acid is used as the solution medium to make the acidity of the sample less than 2.

[0008] Furthermore, the model of the inductively coupled plasma optical emission spectrometer is Optima 5300DV.

[0009] Furthermore, the samples When using ICP-AES to determine total sulfur in geothermal water, it is possible to replace SO 4 2- .

[0010] Furthermore, if the sulfide content in the water sample is Calculate the sulfate content in water by subtraction method

[0011] ρ 硫酸盐S =ρ 全S -ρ 硫化物S .

[0012] The advantages and positive effects of the present invention are:

[0013] The present invention solves the problem of determining trace elements in geothermal water with high mineralization, and establishes a method for directly determining multiple elements in geothermal water using ICP-MS. The experimental results show that the method is efficient and reliable, easy to operate, simplifies the sample pretreatment process, and the determination results are consistent with the traditional test method, with the advantages of low detection limit, good precision, and high spike recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the relationship between the concentration of As in geothermal water and time;

[0015] Figure 2 This is the relationship between the concentration of element B in geothermal water and time;

[0016] Figure 3 This is the relationship between the concentration of Ca in geothermal water and time;

[0017] Figure 4 This is the relationship between the concentration of Fe in geothermal water and time;

[0018] Figure 5 This is the relationship between the concentration of K element in geothermal water and time;

[0019] Figure 6 This is the relationship between the concentration of Li in geothermal water and time;

[0020] Figure 7 This is the relationship between the concentration of Mg in geothermal water and time;

[0021] Figure 8 This is the relationship between the concentration of Na in geothermal water and time;

[0022] Fig. 9 SO in geothermal water 4 2- Graph showing the relationship between element concentration and time;

[0023] Fig.10 SiO in geothermal water 2 Graph showing the relationship between element concentration and time;

[0024] Fig.11 This is a graph showing the relationship between the concentration of Sr in geothermal water and time. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0026] The present invention uses ICP-AES to determine 11 major and minor elements potassium, sodium, calcium, magnesium, silicon, boron, lithium, strontium, arsenic, iron, chlorine and sulfate in geothermal water. The method has the advantages of simultaneous analysis of multiple elements, simple sample pretreatment, less interference and rapid determination.

[0027] Optima 5300DV inductively coupled plasma emission spectrometer (PerkinElmer, USA) uses a cross-nebulizer and axial and radial bidirectional observation modes. After multiple tests and optimization under high altitude and low pressure conditions (3700m above sea level), the best working conditions of the instrument were determined. The instrument working conditions are shown in Table 1.

[0028] Table 1 Optimal working conditions of the instrument

[0029]

[0030] HNO 3 (ρ=1.42g / mL): high purity;

[0031] HCl (ρ=1.19 g / mL): high purity.

[0032] Multi-element mixed standard stock solution: Select a certified mixed standard solution or single standard solution of corresponding concentration and dilute to the required concentration (see Table 2); you can also prepare a single element standard stock solution and mix it into a multi-element standard stock solution.

[0033] Experimental water: deionized water.

[0034] Table 2 Multi-element mixed standard stock solutions

[0035]

[0036] The geothermal water samples used for determination in this application were collected from Riduo Hot Spring in Mezhugongka County, Lhasa City, Tibet Autonomous Region. The temperature of the geothermal water mouth was 82°C, and the mineralization was 1200 mg / L. The sampling container was a high polyethylene plastic bottle. The samples were collected as original samples, nitric acid acidified samples (after collecting the geothermal water sample with a plastic bottle with a volume of 1L, 10mL of nitric acid was added at the sampling site to make the sample acidity <2), and hydrochloric acid acidified samples (after collecting the geothermal water sample with a plastic bottle with a volume of 1L, 10mL of hydrochloric acid was added at the sampling site to make the sample acidity <2).

[0037] The elements measured by this method are the major and minor elements in geothermal water, but the contents of each component in different types of geothermal water are different. The Optima 5300DV inductively coupled plasma emission spectrometer has a two-way observation mode. In actual sample testing, the appropriate observation mode can be selected according to the signal intensity. In order to ensure high sensitivity and as wide a linear range as possible, this method selects spectral lines with high sensitivity and less spectral interference as analytical spectral lines through experimental comparison, and adopts different observation modes. The selection of analytical spectral lines, observation methods, background subtraction points and integration methods of each element are shown in Table 3.

[0038] Table 3 Analysis spectrum and observation method of each element to be measured

[0039]

[0040]

[0041] Under the selected instrument conditions, the sample blank was continuously measured 10 times, and the detection limit of the method was calculated with 3 times the standard deviation. 3 times the detection limit was used as the lower limit of the method, and the highest point of the standard curve was used as the upper limit of the method. The detection limit and measurement range of the method are shown in Table 4.

[0042] Table 4 Method detection limit and detection range

[0043]

[0044] In actual sample testing, if the element content in the sample exceeds the upper limit of the method determination, the sample can be diluted according to the actual situation.

[0045] In order to investigate the influence of solution medium and storage time on the test results, the original sample, 1% nitric acid acidified sample and 1% hydrochloric acid acidified sample were tested and compared for 5 consecutive weeks. The acidified sample was the geothermal water sample acidified on site. The test results are shown in Table 5. The relationship between the element content in geothermal water and time is shown in Table 5. Figure 1 .

[0046] Table 5 Effect of solution medium on test results

[0047]

[0048] From the comparison of test results (Table 5) and the relationship between the concentration of each element in geothermal water and time, it can be seen that the concentration of each component in geothermal water, except for As, B, and Fe, is basically the same as that of the original sample and the acidified sample; the original sample test results of As, B, and Fe are significantly lower than the acidified sample test results ( Figure 1 , Figure 2 , Figure 4 ), which may be due to the hydrolysis and precipitation of the three elements As, B, and Fe in the original sample or adsorption on the wall surface as the environment changes after sampling. Within 5 weeks, the Fe concentration in the original sample decreased significantly. Iron red precipitation appeared in the sampling bottle on the second day and basically reached the lowest value on the 14th day ( Figure 4 ), the concentrations of all elements in the acidified samples did not change significantly. The comparison of test results shows that sample acidification can prevent the loss of elements caused by hydrolysis precipitation or wall adsorption, and the samples did not decrease significantly during the 5-week storage time. The test results of the two acidified water samples are not much different. Considering the determination of other elements, especially when using the ICP-MS method, the hydrochloric acid medium may interfere. Therefore, 1% nitric acid medium is selected for the preservation of geothermal water samples in this paper.

[0049] Since the sulfur in groundwater is mainly in the form of SO 4 2- The sulfur content of other forms is low and needs to be fixed on site. Therefore, ICP-AES can be used to determine the total sulfur in groundwater to approximately replace SO 4 2- Unlike general groundwater, geothermal water often contains sulfides. When studying some hot springs in the Tibet Autonomous Region, it was found that most geothermal water contains sulfides (see Table 6). 4 2- is the total sulfur content in the sample. By calculation, When the sulfate error is less than 5%, ICP-AES can be used to determine the total sulfur in geothermal water to approximately replace SO 4 2- If the sulfide content in the water sample is high ( ), the sulfate content in the water needs to be calculated by subtraction (Formula 1). It should be noted that sulfide sulfur needs to be fixed on-site during sampling.

[0050] ρ 硫酸盐S =ρ 全S -ρ 硫化物S (Formula 1)

[0051] Table 6 Distribution of sulfur content in some hot spring waters in Tibet Autonomous Region

[0052]

[0053] The spike recovery experiment was carried out using the original sample of Riduo Hot Spring geothermal water and the nitric acid-acidified sample, and the recovery rate was calculated. As can be seen from Table 7, the spike recovery rate of the nitric acid-acidified sample was 95.5% to 105.8%, which was better than the spike recovery rate of the original sample of 93.5% to 108.0%. The accuracy of the method can be guaranteed by using ICP-AES to measure geothermal water.

[0054] Nitric acid acidified samples of geothermal water from Riduo Hot Spring were taken, and the water samples were measured 10 times at different times using the same laboratory and the same instrument, and the relative standard deviation (RSD) of the content of each element was calculated. As can be seen from the results in Table 8, the RSD of each element is less than 6%, indicating that the precision of this method is good.

[0055] Table 7 Spiked recovery

[0056]

[0057] Table 8 Method precision

[0058]

[0059] Due to the lack of geothermal water standard materials for quality control, the accuracy of ICP-OES measurement data was verified by comparing the results of different methods. K, Na, Li, Sr, and Fe were measured by atomic absorption spectrometry (AAS), Ca and Mg were measured by EDTA titration (VOL), B was measured by mannitol-alkali titration (VOL), As was measured by atomic fluorescence spectrometry (AFS), Si was measured by silicon molybdenum blue colorimetry (COL), and SO 4 2- Ion chromatography (IC) was used. As can be seen from the data in Table 9, the data determined by ICP-AES and the traditional method are basically consistent.

[0060] Table 9 Comparison of data measured by ICP-OES and traditional methods

[0061]

[0062]

[0063] Note: B, Ca, Mg, SO 4 、SiO 2 The original sample was used for comparative determination, and the nitric acid-acidified sample was used for determination of other elements.

[0064] The Optima 5300DV plasma emission spectrometer has a two-way observation mode, which can meet the simultaneous determination of 11 major and minor elements in geothermal water, including potassium, sodium, calcium, magnesium, silicon, boron, lithium, strontium, arsenic, iron and sulfate. After the spike recovery test, precision test and comparison with the data of the traditional method, it is proved that this method is efficient, reliable and practical. When the total sulfur measured by this method is 4 2- In addition, the test results of geothermal water sample preservation conditions showed that the element content of water samples acidified with 1% nitric acid would not change significantly within 5 weeks.

[0065] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept, which all belong to the protection scope of the present invention.

Claims

1. A method for detecting hot spring water, It is characterized in that The 11 major and minor elements potassium, sodium, calcium, magnesium, silicon, boron, lithium, strontium, arsenic, iron, chlorine and sulfate in geothermal water were determined using an inductively coupled plasma emission spectrometer, a cross-nebulizer, and axial and radial bidirectional observation modes.

2. The method for detecting hot spring water according to claim 1, It is characterized in that The power of the inductively coupled plasma emission spectrometer was set to 1300 W, the auxiliary gas flow rate was 0.2 L / min, the nebulizer flow rate was 0.67 L / min, the plasma flow rate was 15 L / min, the nebulizer pressure was 105 KPa, the injection volume was 1.5 mL / min, and the integration time was 2 to 10 s.

3. The method for detecting hot spring water according to claim 2, It is characterized in that Use 5% hydrochloric acid or nitric acid as the solution medium to make the sample acidity less than 2.

4. The method for detecting hot spring water according to claim 3, It is characterized in that The model of the inductively coupled plasma optical emission spectrometer is Optima 5300DV.

5. The method for detecting hot spring water according to claim 4, It is characterized in that In the sample When using ICP-AES to determine total sulfur in geothermal water, it is possible to replace SO 4 2- .

6. The method for detecting hot spring water according to claim 5, It is characterized in that If the sulfide content in the water sample Calculate the sulfate content in water by subtraction method r 硫酸盐s =ρ 全s -r 硫化物s 。

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