CN103332807B - Degradation method for bisphenol A in water in tap water pipeline network - Google Patents

Abstract

The invention discloses a method for degrading bisphenol A in water in a tap water pipe network. The pH of the internal water is 6-9; sodium hypochlorite is then added to the tap water pipe network, so that the residual chlorine concentration in the tap water pipe network reaches 0.1-0.7mg/L, and after the degradation reaction, the degradation of bisphenol A is completed. The method for degrading bisphenol A in the water in the tap water pipe network of the present invention is through adjusting the flow rate of the water in the tap water pipe network, adjusting the pH of the water in the tap water pipe network by using phosphoric acid and sodium hydroxide, and adding sodium hypochlorite to degrade bisphenol A. Condition control completes the rapid degradation of bisphenol A, the degradation rate of bisphenol A is fast, the water quality meets the sanitary standard of drinking water, the operation is simple and easy, and it is easy to implement in industrialization, and has broad application prospects.

Description

A method for degrading bisphenol A in water in a tap water pipe network

technical field

The invention relates to the field of water treatment methods, in particular to a method for degrading bisphenol A in water in a tap water pipe network.

Background technique

Bisphenol A (bisphenol A, BPA) is a typical environmental endocrine disruptor, which is widely used in many industries. BPA may leak into the environment during production, synthesis, transportation, and use. BPA is a compound with biological toxicity and estrogenic effects. It is a low-toxic substance and has moderate irritation to the skin, respiratory tract, digestive tract, and cornea. It can cause increased incidence of leukemia and lymphoma in female and male rats, and is teratogenic. At present, it has been detected in natural water bodies, treated drinking water, sewage treatment plant effluent, river and lake sediments and animal tissues in many countries and regions around the world. With the rapid development of industry in recent years, my country's water bodies are more seriously polluted by endocrine disruptors such as BPA.

Sodium hypochlorite disinfection is a disinfection method commonly used in water plants in my country. Its advantages are low cost and obvious disinfection effect. The disadvantage is that it decays faster in water with poor water quality. At the same time, sodium hypochlorite can react with various endocrine disruptors including BPA, and degrade them by chlorination.

In recent years, the reaction degradation of BPA and sodium hypochlorite has been studied by many scholars, but most of these studies only considered the simple reaction of the two in pure water environment and beaker experiments. However, the drinking water in the actual pipe network is much more complicated due to the existence of natural organic matter, inorganic salt ions and pipe scale, and the law of BPA degradation is also different from the chlorination products. Therefore, the simple beaker experiment cannot well reflect the degradation law of BPA in the actual pipe network, let alone effectively degrade BPA in drinking water in the tap water pipe network.

Application publication number CN101968474A discloses the method for detecting bisphenol A in drinking water and beverage food by LC-MS/MS, comprising the following steps: (1) Determination of LC-MS/MS: 1, LC-MS chromatographic conditions: according to bisphenol A retains properties in the chromatographic column, select the chromatographic column, and formulate chromatographic analysis conditions; II, MS conditions: adopt conventional bisphenol A mass spectrometry analysis conditions; (2) standard curve drawing; (3) sample detection: compare the detection results with the standard Curve comparison, calculate the content of bisphenol A in the sample. However, this technical solution only discloses the detection of bisphenol A in drinking water, and does not provide a technical solution for removing bisphenol A in drinking water.

The Chinese invention patent application with the application publication number CN102198313A discloses the application of a food-grade microbial probiotic in degrading bisphenol A. Any one or more of Bacillus subsp. bulgaricus, Lactobacillus casei and Bacillus subtilis natto. The above-mentioned food-grade microbial probiotics can effectively degrade bisphenol A in yogurt, but using the food-grade microbial probiotics to degrade bisphenol A in drinking water in the tap water pipe network will introduce bacteria on the one hand, and there is a certain risk. On the one hand, the cost of using food-grade microbial probiotics to degrade bisphenol A in drinking water in the tap water network is also relatively high.

Contents of the invention

The invention provides a method for degrading bisphenol A in water in a tap water pipe network, which can effectively degrade bisphenol A in water.

A method for degrading bisphenol A in water in a tap water pipe network, comprising the following steps:

(1) Adjust the flow velocity of the water in the tap water pipe network to 0.5m/s~2m/s, add phosphoric acid and sodium hydroxide, and adjust the pH of the water in the tap water pipe network to 6~9;

(2) Then add sodium hypochlorite to the tap water pipe network, so that the concentration of residual chlorine in the water in the tap water pipe network reaches 0.1-0.7mg/L. After the degradation reaction, the degradation of bisphenol A is completed.

The residual chlorine is free residual chlorine, which refers to the oxidation state contained, that is, the oxidation state chlorine with a valence of 0, +1, +3, +4, +5, +7, and the residual chlorine in the drinking water pipe network. The chlorine concentration refers to the sum of the concentrations of Cl ₂ , HClO and ClO ⁻ .

In step (1), the flow velocity of water in the tap water pipe network is adjusted to 0.5m/s-2m/s. Under different flow velocities, the intensity of water flow turbulence is different, and the degree of difficulty of material exchange between substances such as BPA and pipe scale is different. The water flow rate has a certain influence on the degradation rate of BPA. As a preference, the water flow rate in the tap water pipe network is adjusted to 1m/s~1.8m/s, which is very suitable for the degradation of BPA. More preferably, the flow velocity of the water in the water pipe network is adjusted to 1.8m/s.

Preferably, the phosphoric acid is added in the form of phosphoric acid aqueous solution, the sodium hydroxide is added in the form of sodium hydroxide aqueous solution, and both phosphoric acid and sodium hydroxide are in the form of aqueous solution, which is beneficial to the addition of phosphoric acid and sodium hydroxide In the water pipe network, on the other hand, in the form of an aqueous solution, the addition of phosphoric acid and sodium hydroxide can be accurately controlled, which is beneficial to the degradation of bisphenol A in the water in the water pipe network.

More preferably, the concentration of the phosphoric acid aqueous solution is 60-100g/L, more preferably 80g/L, the concentration of the sodium hydroxide aqueous solution is 3-10g/L, more preferably 7g/L, the above-mentioned concentration Phosphoric acid aqueous solution and sodium hydroxide aqueous solution can well adjust the pH of the water in the tap water pipe network, which is beneficial to the degradation of bisphenol A in the water pipe network.

As a preference, when adding phosphoric acid and sodium hydroxide to the tap water pipe network, add sodium bromide to adjust the concentration of bromide ions in the water in the tap water pipe network to be 0.01-0.06 mg/L, and bromide ions at an appropriate concentration will react with residual chlorine The reaction produces hypobromous acid, which can react with BPA to degrade BPA, so the presence of bromide ions can accelerate the degradation of BPA, and the above-mentioned concentration of bromide ions is very conducive to the degradation of BPA. Further preferably, the concentration of bromide ions in the water in the tap water pipe network is adjusted to 0.06 mg/L.

Further preferably, the sodium bromide is added in the form of an aqueous sodium bromide solution, the concentration of the aqueous sodium bromide solution is 60-100 g/L, more preferably 82.4 g/L, in the form of an aqueous sodium bromide solution, It is beneficial to add sodium bromide into the tap water pipe network, and can accurately control its addition amount, and more importantly, it is beneficial to the degradation of bisphenol A in the water pipe network.

Add phosphoric acid and sodium hydroxide to adjust the pH of the water in the tap water pipe network to 6-9. BPA exists in different forms in different pH environments. The lower the pH, the greater the proportion of molecular BPA; conversely, the greater the pH, the greater the proportion of ionic BPA, and the degradation rates of different forms of BPA are different. The standard stipulates that the pH of tap water should be between 6 and 9. Adding phosphoric acid and sodium hydroxide can adjust the pH of the main water in the tap water pipe network. Preferably, the pH of the water in the tap water pipe network is adjusted to 7.2-8, which is very suitable for the degradation of BPA. More preferably, the pH of the water in the tap water pipe network is adjusted to 8.

Preferably, the temperature of the water in the tap water pipe network is 10°C to 30°C. On the one hand, the above temperature is conducive to the degradation of bisphenol A in the water in the tap water pipe network. On the other hand, 10°C to 30°C is the commonly used ambient temperature. Therefore, the degradation of BPA can be carried out at ambient temperature without additional cost for temperature control. Further preferably, the temperature of the water in the tap water pipe network is 25°C-30°C.

In step (2), sodium hypochlorite can undergo a chlorination reaction with BPA. First, the chlorination reaction on the benzene ring occurs, and then the carbon-carbon bond between the propyl group and the benzene ring is broken, and finally the benzene ring is opened, and finally BPA is degraded into small molecular.

As a preference, the sodium hypochlorite is added in the form of an aqueous sodium hypochlorite solution, and the use of the aqueous sodium hypochlorite solution is beneficial to the addition of sodium hypochlorite to the tap water pipe network, while accurately controlling the amount added. Further preferably, the sodium hypochlorite aqueous solution contains 5% to 15% free chlorine by weight, free chlorine refers to the sum of hypochlorous acid (HClO) and hypochlorite (ClO ⁻ ). Further preferably, the sodium hypochlorite aqueous solution in which the weight percentage of free chlorine in the described sodium hypochlorite aqueous solution is 10%.

Preferably, sodium hypochlorite is added to the tap water pipe network so that the concentration of residual chlorine in the water in the tap water pipe network reaches 0.3-0.5 mg/L, which can effectively and quickly degrade the BPA in the water in the tap water pipe network.

Preferably, the time for the degradation reaction is 10 minutes to 80 minutes, and the degradation of BPA is completed after 10 minutes to 80 minutes of the degradation reaction. More preferably, the time for the degradation reaction is 30 minutes to 65 minutes, more than 95% of the BPA can be degraded, and the degradation of BPA is completed.

The tap water obtained from the water source without degraded bisphenol A complies with the Hygienic Standard for Drinking Water (GB5749-2006) and can be used in daily life.

Compared with prior art, the present invention has following advantage:

The method for degrading bisphenol A in the water in the tap water pipe network of the present invention is through adjusting the flow rate of the water in the tap water pipe network, adjusting the pH of the water in the tap water pipe network by using phosphoric acid and sodium hydroxide, and adding sodium hypochlorite to degrade bisphenol A. Condition control completes the rapid degradation of bisphenol A, the degradation rate of bisphenol A is fast, the operation is simple and easy, and it is easy for industrial implementation, and has broad application prospects.

The physical and chemical parameters of the tap water treated by the degradation method of the present invention are all controlled to meet the Hygienic Standard for Drinking Water (GB5749-2006), ensuring water quality safety and meeting the requirements of daily life.

Description of drawings

Fig. 1 is the degradation curve of bisphenol A in the water pipe network of embodiment 1 and embodiment 2;

Fig. 2 is the degradation curve of bisphenol A in the water pipe network of embodiment 1 and embodiment 3;

Fig. 3 is the degradation curve of bisphenol A in the water pipe network of embodiment 1 and embodiment 4;

Fig. 4 is the degradation curve of bisphenol A in the water pipe network of embodiment 1 and embodiment 5;

Fig. 5 is the degradation curve of bisphenol A in the water pipe network of Example 1 and Example 6.

Detailed ways

Example 1

(1) Take the water source that has not degraded bisphenol A. After testing, the concentration C ₀ of bisphenol A in the water source is 100 μg/L. It will be passed into the tap water pipe network, and the flow rate of the water in the tap water pipe network will be adjusted to 1m /s, the temperature of the water in the tap water pipe network is controlled at 25°C, add a phosphoric acid aqueous solution with a concentration of 80g/L and a sodium hydroxide aqueous solution with a concentration of 7g/L, and adjust the pH of the water in the tap water pipe network to 7.2;

(2) Add sodium hypochlorite aqueous solution with a free chlorine content of 10% by weight to the tap water pipe network, so that the concentration of residual chlorine in the water in the tap water pipe network reaches 0.3mg/L. After a period of degradation reaction, the double Degradation of phenol A.

Take 200mL of water samples from the tap water pipe network at different times t into 250mL brown bottles with lids, add 2mL of ascorbic acid aqueous solution (100mg/L) to fix. The different time t (min) is calculated from the time when the water source without degraded bisphenol A is introduced into the tap water pipe network and then the sodium hypochlorite aqueous solution is added. For example, at the 60th minute, take 200 mL of water sample from the tap water pipe network into a 250 mL brown bottle with a lid, and add 2 mL of ascorbic acid aqueous solution (100 mg/L) to fix it. Then use high performance liquid chromatography to measure the concentration of bisphenol A in the water sample, and obtain the concentration of bisphenol A in the water in the tap water pipe network at the 60th minute.

Use high-performance liquid chromatography to measure the concentration of bisphenol A in water samples, C ₀ is the concentration C ₀ of bisphenol A in the water source, C is the concentration of bisphenol A in the water pipe network, and C/C ₀ is the Y axis , time is the X-axis, and the bisphenol A degradation curve is drawn, and the time-consuming curve is 60 minutes. As shown in Figure 1, the BPA degradation rate is 90% and it takes 65 minutes.

Example 2

In step (1), the pH of the water in the tap water pipe network was adjusted to 8, and the rest was the same as in Example 1. The degradation curve of bisphenol A is shown in Figure 1 .

As shown in Figure 1, pH=8.0 can not only degrade bisphenol A quickly and effectively, but also meet the stability of water quality in the water pipe network and the water consumption requirements of users, so the optimal pH value for degrading bisphenol A in the water pipe network is pH= 8.0.

Example 3

In step (2), add the sodium hypochlorite aqueous solution that the weight percent of free chlorine is 10% to tap water pipe network, make the residual chlorine concentration in the water in tap water pipe network reach 0.5mg/L, all the other are the same as embodiment 1, embodiment The bisphenol A degradation curves of 1 and Example 3 are shown in Figure 2.

As shown in Figure 2, in Example 1, at 0.3mg/L residual chlorine concentration, it takes 65 minutes for the BPA degradation rate to reach 90%; while in Example 3, at 0.5mg/L residual chlorine concentration, BPA can be degraded in a very short time. Time degradation, BPA90% degradation rate only takes 15 minutes. At the same time, considering that excessive residual chlorine in the tap water pipe network will affect the taste of drinking water and increase the cost of dosing, the optimal concentration of residual chlorine for BPA degradation is 0.5mg/L.

Example 4

In step (1), the temperature of the water in the tap water pipe network is controlled at 30° C., and the rest is the same as in Example 1. The bisphenol A degradation curves of Examples 1 and 4 are shown in FIG. 3 .

As shown in Figure 3, the temperature of the water in the tap water pipe network is controlled at 30°C, which is conducive to the degradation of BPA. In Example 4, the degradation rate of BPA exceeds 90% after 35 minutes. Since the temperature in the tap water pipe network is up to about 30°C in summer in the south, the optimum temperature for BPA degradation in the tap water pipe network is 30°C.

Example 5

In step (1), the flow velocity of water in the tap water pipe network was adjusted to 1.8m/s, and the rest was the same as in Example 1. The degradation curves of bisphenol A in Example 1 and Example 5 are shown in Figure 4.

As shown in Figure 4, the increase of the flow rate of 1.8m/s is conducive to the degradation of BPA. In Example 5, the BPA degradation rate exceeds 90% after 50 minutes, which is slightly higher than that of the flow rate of 1.0m/s. Therefore, the optimal flow rate for the degradation of bisphenol A in water pipe network is 1.8m/s.

Example 6

In step (1), while adding phosphoric acid and sodium hydroxide to the tap water pipe network, add sodium bromide aqueous solution with a concentration of 82.4g/L to adjust the bromide ion concentration in the tap water pipe network to 0.06mg/L, and the rest Same as Example 1, the bisphenol A degradation curves of Example 1 and Example 6 are shown in Figure 5.

As shown in Figure 5, the increase of bromide ion concentration is beneficial to the degradation of BPA. Experiments have proved that the bromide ion concentration exceeds 0.06mg/L, and the degradation rate of BPA does not increase. Therefore, the optimal bromide ion concentration of water in the tap water pipe network is 0.06mg/L.

Take the water source that has not degraded bisphenol A, that is, bisphenol A does not meet the "Drinking Water Hygienic Standard" (GB5749-2006), and the tap water obtained through the treatment of Examples 1 to 6 meets the "Drinking Water Hygienic Standard" (GB5749-2006). 2006), can be used in daily life.

Comparative example 1

Take the water source that has not degraded bisphenol A, put the water source in the reaction pool, control the temperature of the water at 25°C, add an aqueous sodium hypochlorite solution with a free chlorine content of 10% by weight, so that the water in the tap water pipe network The concentration of residual chlorine reached 0.5mg/L, and the degradation reaction was carried out. After 1 hour, the BPA degradation rate was 19%, after 2 hours, the BPA degradation rate was 33%, after 3 hours, the BPA degradation rate was 45%, and after 4 hours, the BPA degradation rate After 5 hours, the BPA degradation rate was 66%, after 6 hours, the BPA degradation rate was 71%, after 7 hours, the BPA degradation rate was 76%, after 8 hours, the BPA degradation rate was 80%, and after 8h to 12h, Degradation is very slow, basically the final BPA degradation rate is 80%.

Claims (1)

1. a method for degrading bisphenol A in water in a tap water pipe network, is characterized in that, comprises the following steps: (1) Adjust the flow rate of the water in the tap water pipe network to 1m/s~1.8m/s, the temperature of the water in the tap water pipe network is 10℃~30℃, add phosphoric acid and sodium hydroxide to adjust the flow rate of the water in the tap water pipe network The pH is 7.2-8; Described phosphoric acid is added in the form of phosphoric acid aqueous solution, and described sodium hydroxide is added in the form of sodium hydroxide aqueous solution, and the concentration of described phosphoric acid aqueous solution is 60～100g/L, and the concentration of described sodium hydroxide aqueous solution is 3～10g/L; While adding phosphoric acid and sodium hydroxide in the tap water pipe network, add sodium bromide, adjust the bromide ion concentration in the water in the tap water pipe network to be 0.01～0.06mg/L, described sodium bromide is the sodium bromide aqueous solution Form to add, the concentration of the sodium bromide aqueous solution is 60 ~ 100g/L; (2) Then add sodium hypochlorite to the tap water pipe network, so that the residual chlorine concentration in the tap water pipe network reaches 0.3-0.5mg/L. After the degradation reaction, the degradation reaction time is 10min-80min, and the degradation of bisphenol A is completed. ; The sodium hypochlorite is added in the form of an aqueous sodium hypochlorite solution, and the weight percentage of free chlorine in the aqueous sodium hypochlorite solution is 5% to 15% of the aqueous sodium hypochlorite solution.