Treatment method for removing fluorine from high-fluorine hot spring water and improving quality while retaining beneficial trace mineral elements

Abstract

The application discloses a treatment method for removing fluorine and improving quality of high-fluorine hot spring water while retaining beneficial trace mineral elements. After adding a proper amount of active magnesium oxide powder to high-fluorine hot spring water, the fluorine ions in the high-fluorine hot spring water are effectively removed through oscillation adsorption, the fluorine content in the high-fluorine hot spring water is reduced to below the limited value of the national standard GB8537-2008 of mineral water, the beneficial trace mineral elements in the hot spring water are effectively retained, the total hardness concentration of the hot spring water is lower than the recommended value (18.70mg / L<150mg / L) of the World Health Organization for magnesium in drinking water, namely, the drinking water treated by the method meets the national drinking water standard. The raw material is easy to obtain, the adsorption material is simple to prepare, low in cost and convenient to use, and is suitable for promotion.

Description

Technical Field

[0001] This invention relates to the field of hot spring water defluoridation technology, specifically a treatment method for high-fluoride hot spring water that removes fluoride, improves its quality, and retains beneficial trace mineral elements. Background Technology

[0002] Hot springs, as a valuable geothermal resource, contain special minerals such as fluoride and metasilicic acid, which have high physiological and therapeutic value for disease prevention and treatment. However, geothermal hot spring water, after long-term water-rock interaction, often has severely excessive fluoride levels when used as drinking water. Endemic fluorosis is a type of endemic disease caused by drinking water with excessive fluoride content. China's standard for safe drinking water is a fluoride concentration not exceeding 1 mg / L.

[0003] While hot springs with high fluoride content play an important role in bathing therapy, they pose significant risks as drinking water. The scientific use of hot spring water is an important measure to ensure the safety of drinking water for residents in areas prone to fluorosis.

[0004] As shown in Table 1, the main defluoridation technologies for high-fluoride hot spring water currently include adsorption, precipitation, ion exchange, electrochemical methods, and membrane separation. Among these, adsorption is currently the most widely used and lowest-cost method for defluoridation of hot spring water. Commonly used defluoridation adsorbents include activated metal oxides, bone char, zeolite, and activated carbon. Precipitation methods are mainly divided into chemical precipitation and coagulation precipitation. These methods primarily involve adding compounds to form water-insoluble fluoride-containing precipitates, or utilizing the complexation reaction between compounds and fluoride ions to form co-precipitates. The most commonly used precipitant in chemical precipitation is calcium salt, which mainly relies on Ca2+. 2+ With F - The formation of CaF2 precipitate achieves defluorination; however, calcium fluoride has a certain solubility in water, and this method can only reduce the fluoride concentration in water to 8-10 mg / L, and produces a large amount of sludge. Aluminum salts are commonly used coagulants in coagulation and sedimentation methods, but their defluorination efficiency is related to the solution's pH, alkalinity, the types and concentrations of coexisting anions, and is affected by operating conditions such as stirring conditions and settling time, resulting in unstable defluorination effects. Electrochemical methods mainly rely on electrodialysis. This method requires high voltage control; too low a voltage leads to low fluoride removal rates, while too high a voltage easily causes electrode scaling, reduces current efficiency, and increases maintenance costs. Membrane separation utilizes the selective permeability of membranes to separate mixtures. For example, Wang Yukun et al. used reverse osmosis to remove fluoride from high-fluoride drinking water (2.19 mg / L) in Nanpaihe Town, Cangzhou City, Hebei Province, achieving a removal efficiency of 93.2%. However, its disadvantages include poor selectivity, which removes other beneficial chemical elements in the water while reducing the fluoride content. Furthermore, membrane modules are prone to fouling and clogging, have poor durability and short lifespan, and the problem of treating the concentrated water after treatment is difficult to solve.

[0005] Table 1. Comparison of Water Defluoridation Technologies

[0006]

[0007] In summary, current defluoridation technologies for high-fluoride hot spring water are not very effective, and the beneficial trace minerals in the hot spring water are easily lost, which are common problems faced by existing defluoridation technologies for high-fluoride hot spring water. Summary of the Invention

[0008] The present invention aims to provide a method for treating high-fluoride hot spring water by removing fluoride and improving its quality while retaining beneficial trace minerals. This method effectively removes fluoride from hot spring water while retaining beneficial trace minerals, resulting in better water quality that is non-toxic and harmless.

[0009] To achieve the above objectives, this invention provides a method for treating high-fluoride hot spring water by defluoridation and quality improvement while retaining beneficial trace minerals, comprising the following steps:

[0010] Step 1: Take samples of high-fluoride hot spring water and determine the fluoride content (F) in the samples. - The concentration was measured, and the beneficial trace mineral elements K, Ca, Na, Mg, Fe, Mn, Li, Sr, characteristic component H2SiO3, and water quality indicators such as pH, EC, DO, and TDS in the high-fluoride hot spring water sample were determined.

[0011] Step 2: Using magnesium hydroxide as a precursor, active magnesium oxide powder is obtained by high-temperature calcination;

[0012] Step 3: Take a certain amount of the high-fluoride hot spring water sample from Step 1 and place it in an Erlenmeyer flask. Add the activated magnesium oxide powder from Step 2 to the Erlenmeyer flask. Place the Erlenmeyer flask in a constant-temperature shaker and shake to adsorb for a certain period of time. Then filter and separate the activated magnesium oxide, and determine the fluoride content in the filtrate. - The concentration of beneficial trace mineral elements K, Ca, Na, Mg, Fe, Mn, Li, Sr, characteristic component H2SiO3, and water chemical parameters pH, EC, DO, and TDS in the filtrate were measured, and the changes in total hardness before and after were calculated.

[0013] Preferably, in step one, the F in the high-fluoride hot spring water sample... - The concentration range is 2.0~20 mg / L.

[0014] Preferably, the magnesium hydroxide content in the magnesium hydroxide precursor in step two is 98.00~99.99%.

[0015] Preferably, in step two, the specific preparation process of activated magnesium oxide is as follows: First, a certain mass of magnesium hydroxide powder is weighed and placed in a muffle furnace for high-temperature calcination. After the high-temperature calcination is completed, the muffle furnace is cooled to room temperature, and then removed and placed in a sealed container for later use; wherein the heating rate during the high-temperature calcination process is 10... oC / min, high-temperature calcination temperature is 420 o C, the high-temperature roasting time is 2 hours; the cooling process is natural cooling.

[0016] Preferably, in step three, the mass ratio of the high-fluoride hot spring water sample to active magnesium oxide is 100:1 to 30:1, the shaking adsorption time is 1 to 24 hours, and the temperature of the constant-temperature shaker is 25 to 80 degrees Celsius. o C, the rotation speed of the constant temperature shaking incubator is 100~250 r / min.

[0017] Compared with existing technologies, this invention effectively removes fluoride ions from high-fluoride hot spring water samples by adding an appropriate amount of the active magnesium oxide powder of this invention and then adsorbing it through vibration. This reduces the fluoride content in the hot spring water to below the limit specified in the national standard GB8537-2008 for mineral water, while effectively retaining beneficial trace minerals. Furthermore, the total hardness concentration of the hot spring water is lower than the World Health Organization's recommended magnesium level for drinking water (18.70 mg / L < 150 mg / L), meaning the drinking water treated by this method meets national drinking water standards. The raw materials for this invention are readily available, and the adsorption material is simple to prepare, low in cost, and easy to use, making it suitable for widespread application. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the active magnesium oxide of the present invention.

[0019] (a) is the actual active magnesium oxide, (b) is the SEM image of active magnesium oxide, and (c) is the elemental distribution map of active magnesium oxide. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments. Example

[0021] A method for treating high-fluoride hot spring water by removing fluoride and improving its quality while retaining beneficial trace minerals includes the following steps:

[0022] Take 100g of magnesium hydroxide precursor with a mass fraction of 99.5% and place it in a porcelain crucible. Put the porcelain crucible into a muffle furnace, and heat the muffle furnace at 10°C. o Heating rate increased to 420 °C / min o After calcination at C for 2 hours, activated magnesium oxide was obtained after the muffle furnace cooled naturally to room temperature. Images of the activated magnesium oxide, its microstructure, and elemental composition are shown below. Figure 1As shown in Table 2, 30 g of high-fluoride hot spring water sample was placed in a 50 mL conical flask, and the water temperature was kept at 25℃. 0.3 g of the previously prepared active magnesium oxide powder was added to the conical flask. The conical flask was placed in a constant temperature shaker at 100 r / min for 1 h for adsorption. The insoluble matter in the water was removed by filtration, and hot spring water with pH = 8.3 and fluoride ion (F-) concentration less than 1.5 mg / L was obtained. The content of the main elements in the mineral water before and after treatment is shown in Table 2.

[0023] Table 2

[0024] Example

[0025] Take 30g of high-fluoride hot spring water and place it in a 50mL conical flask. Keep the water temperature at 50℃. Add 0.6g of the active magnesium oxide powder prepared in Example 1 to the conical flask. Place the conical flask in a constant temperature shaker at 150r / min for 12h for adsorption. Filter to remove insoluble matter in the water to obtain mineral water with pH=8.6 and fluoride ion (F-) concentration less than 1.5mg / L. The content of major elements in the mineral water before and after treatment is shown in Table 3.

[0026] Table 3

[0027] Example

[0028] Take 30g of high-fluoride hot spring water and place it in a 50mL conical flask. Keep the water temperature at 80℃. Add 1g of active magnesium oxide powder prepared in Example 1 to the conical flask. Place the conical flask in a constant temperature shaker at 250r / min for 24h for adsorption. Filter to remove insoluble matter in the water to obtain mineral water with pH=9.4 and fluoride ion (F-) concentration less than 1.5mg / L. The content of major elements in the mineral water before and after treatment is shown in Table 4.

[0029] Table 4

[0030] Example

[0031] To further illustrate the beneficial effects of the active magnesium oxide proposed in this invention on defluorination and quality improvement of high-fluoride hot spring water, 30g of high-fluoride hot spring water was placed in a 50mL conical flask, and the water temperature was maintained at 25℃. 0.2g of commercial magnesium-loaded activated natural zeolite was added to the conical flask, and the conical flask was placed in a constant temperature shaker at 125 r / min for 2h for adsorption. The insoluble matter in the water was removed by filtration, and mineral water with pH=7.3 and fluoride ion (F-) concentration less than 9.57 mg / L was obtained. The content of the main elements in the mineral water before and after treatment is shown in Table 5.

[0032] Table 5

[0033] Example

[0034] To further illustrate the beneficial effects of the active magnesium oxide proposed in this invention on defluorination and quality improvement of high-fluoride hot spring water, 30g of high-fluoride hot spring water was placed in a 50mL conical flask, and the water temperature was maintained at 25℃. 0.2g of commercially available transparent light magnesium carbonate was added to the conical flask, and the conical flask was placed in a constant temperature shaker at 125 r / min for 2h for adsorption. The insoluble matter in the water was removed by filtration, and mineral water with pH=8.0 and fluoride ion (F-) concentration less than 8.32 mg / L was obtained. The content of the main elements in the mineral water before and after treatment is shown in Table 6.

[0035] Table 6

[0036]

[0037] This invention is based on extensive indoor experiments and outdoor sampling tests. It is scientific and practical, and provides a new solution for hot spring development and utilization enterprises as well as for the defluoridation and quality improvement of drinking water in areas affected by high fluoride water. It has high economic, environmental and social benefits.

Claims

1. A method for treating high-fluoride hot spring water by defluoridation and quality improvement while retaining beneficial trace minerals, characterized in that, Includes the following steps: Step 1: Take samples of high-fluoride hot spring water and determine the fluoride content (F) in the samples. - The concentration of beneficial trace minerals K, Ca, Na, Mg, Fe, Mn, Li, Sr, characteristic component H2SiO3, and water quality indicators such as pH, EC, DO, and TDS in high-fluoride hot spring water samples were measured simultaneously. Step 2: Using magnesium hydroxide as a precursor, active magnesium oxide powder is obtained by high-temperature calcination; Step 3: Take a certain amount of the high-fluoride hot spring water sample from Step 1 and place it in an Erlenmeyer flask. Add the activated magnesium oxide powder from Step 2 to the Erlenmeyer flask. Place the Erlenmeyer flask in a constant-temperature shaker and shake to adsorb for a certain period of time. Then filter and separate the activated magnesium oxide, and determine the fluoride content in the filtrate. - The concentration was measured, and the beneficial trace mineral elements K, Ca, Na, Mg, Fe, Mn, Li, Sr, characteristic component H2SiO3, and water chemical parameters pH, EC, DO, and TDS in the filtrate were determined. The changes in total hardness before and after were calculated. In step two, the specific preparation process of activated magnesium oxide is as follows: First, a certain mass of magnesium hydroxide powder is weighed and placed in a muffle furnace for high-temperature calcination. After the high-temperature calcination is completed, the muffle furnace is cooled to room temperature, and then removed and placed in a sealed container for later use. The heating rate during the high-temperature calcination process is 10°C. o C / min, high-temperature calcination temperature is 420 o C, the high-temperature roasting time is 2 hours; the cooling process is natural cooling.

2. The method for treating high-fluoride hot spring water by defluorination and quality improvement while retaining beneficial trace minerals, as described in claim 1, is characterized in that... In step one, the F in the high-fluoride hot spring water sample - The concentration range is 2.0~20 mg / L.

3. The method for treating high-fluoride hot spring water by defluorination and quality improvement while retaining beneficial trace minerals, as described in claim 1, is characterized in that... In step two, the magnesium hydroxide precursor contains 98.00-99.99% magnesium hydroxide.

4. The method for treating high-fluoride hot spring water by defluorination and quality improvement while retaining beneficial trace minerals, as described in claim 1, is characterized in that... In step three, the mass ratio of the high-fluoride hot spring water sample to active magnesium oxide is 100:1 to 30:1, the shaking adsorption time is 1 to 24 hours, and the temperature of the constant-temperature shaker is 25 to 80 degrees Celsius. o C, the rotation speed of the constant temperature shaking incubator is 100~250 r / min.

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