A method for treating endocrine disruptors in water with catalysis of layered hydrotalcite material by peroxyacetic acid

Abstract

The application relates to a method for treating endocrine disruptors in water by using layered hydrotalcite material and peracetic acid, belonging to the field of advanced oxidation technology and relating to a method for removing endocrine disruptors in water. The application aims to solve the problems of poor degradation efficiency, short service life of catalysts and high degradation cost in the prior art of using peracetic acid oxidant alone to degrade endocrine disruptors in water. The method comprises the following steps: I, preparing a metal salt solution; II, preparing a mixed solution of sodium hydroxide and sodium carbonate; III, preparing a gel; IV, aging; and V, adding layered hydrotalcite material and peracetic acid into wastewater containing endocrine disruptors to degrade the endocrine disruptors. The degradation rate of the endocrine disruptors in water can reach 100% within 30 minutes. The application is suitable for degrading endocrine disruptors.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of advanced oxidation technology and relates to a method for removing endocrine disruptors in water. BACKGROUND

[0002] Advanced oxidation processes (AOPs) have been widely used for the treatment of refractory wastewater due to their high efficiency in degrading and mineralizing organic pollutants. Reactive species, such as hydroxyl radicals (·OH) and sulfate radicals (SO4 ·- ) are the main oxidants in these systems, which can be generated by precursors (e.g. hydrogen peroxide (H2O2), peroxymonosulfate (PMS) and peroxydisulfate (PDS)). Nowadays, peroxyacetic acid (PAA) is a peroxoacid oxidant widely used for disinfection and sterilization, and is increasingly used as an alternative precursor for AOPs. Peroxyacetic acid oxidant is widely used as a powerful disinfectant and cleaning agent, which has high oxidation efficiency, low tendency to form disinfection by-products and is easier to activate compared with traditional oxidants such as chlorine and H2O2. It has high oxidizing power, with a standard reduction potential (E0=1.06-1.96V) similar to that of chlorine (E0=1.4V) and hydrogen peroxide (E0=1.8V). In addition, PAA has an O-O bond that is easy to activate, which can generate oxidative reaction species such as ·OH, 1 O2 and CH3CO2·. The dissociation energy of the O-O bond in PAA (159kJ / mol) is lower than that in H2O2 (213kJ / mol) and persulfate (317kJ / mol), indicating that PAA is easier to activate.

[0003] The existing problem of using peroxyacetic acid oxidant alone to degrade endocrine disruptors in water is poor degradation efficiency, short catalyst use period and high degradation cost. SUMMARY

[0004] The purpose of the present application is to solve the existing problem of using peroxyacetic acid oxidant alone to degrade endocrine disruptors in water, which is poor degradation efficiency, short catalyst use period and high degradation cost, and to provide a method for treating endocrine disruptors in water using layered hydrotalcite material catalyzed by peroxyacetic acid.

[0005] A method for treating endocrine disruptors in water using layered hydrotalcite material catalyzed by peroxyacetic acid is completed by the following steps:

[0006] I. Preparation of metal salt solution:

[0007] Dissolve divalent metal salt and trivalent metal salt in water to obtain metal salt solution;

[0008] II. Preparation of mixed solution of sodium hydroxide and sodium carbonate:

[0009] Sodium hydroxide and sodium carbonate are dissolved in water to obtain a mixed solution of sodium hydroxide and sodium carbonate;

[0010] 3. Under stirring conditions, a mixed solution of sodium hydroxide and sodium carbonate is added dropwise to the metal salt solution until the pH of the metal salt solution is 10, thus obtaining a gel.

[0011] 4. The gel is aged, then washed with deionized water, dried, and finally ground to obtain layered hydrotalcite material.

[0012] 5. Add layered hydrotalcite material and peracetic acid to wastewater containing endocrine disruptors, adjust the pH of the wastewater to 3-9, and degrade the endocrine disruptors under stirring conditions to complete the method.

[0013] The principle of this invention:

[0014] Layered hydrotalcites (LDHs) consist of divalent metal ions (M... 2+ Cu 2+ Mg 2+ Ni 2+ Zn 2+ The main layer formed by trivalent metal ions (M) 3+ Fe 3+ Al 3+ ) and mainly composed of anions (e.g., NO3-) - and CO3 2- ( ) and water molecules. By selecting metal species and anionic species in the host layer, various types of LDH can be synthesized. This invention is the first to apply layered hydrotalcite to catalyze peracetic acid treatment of endocrine disruptors in water.

[0015] The beneficial effects of this invention are:

[0016] I. This invention prepares Cu-AlLDH catalyst by co-precipitation method, which involves mixing a certain proportion of copper salt and aluminum salt, adjusting the pH with an alkaline solution to produce a gel, and then drying it to obtain Cu-AlLDH.

[0017] II. This invention provides a method for the degradation of bisphenol A in water by Cu-AlLDH-catalyzed peracetic acid. This method utilizes Cu-AlLDH to efficiently activate peracetic acid to generate surface hydroxyl groups, hydrogen peroxide, CH3C(O)O· and CH3C(O)OO·, as well as hydroxyl radicals. These active oxygen species are used to degrade pollutants in water. Compared with the direct treatment of endocrine disruptors in water with peracetic acid, this invention can effectively improve the degradation efficiency of pollutants in water.

[0018] Third, the present invention can achieve a 100% degradation rate of endocrine disruptors in water within 30 minutes. Attached Figure Description

[0019] Figure 1 Degradation curve of bisphenol A catalyzed by Cu-Al LDH prepared in different examples 1-3 with peracetic acid, figure 1 is example 3, 2 is example 1, 3 is example 2;

[0020] Figure 2 Degradation curve of bisphenol A catalyzed by Cu-Al LDH prepared in examples 1, 4, 5 with peracetic acid, figure 1 is example 1, 2 is example 5, 3 is example 4;

[0021] Figure 3 Degradation curve of bisphenol A catalyzed by Cu-Al LDH prepared in examples 1 and 6 with peracetic acid, 1 is example 1, 2 is example 6;

[0022] Figure 4 Degradation curve of bisphenol A catalyzed by Cu-Al LDH prepared in examples 1, 7 and 8, figure 1 is example 1, 2 is example 7, 3 is example 8. DETAILED DESCRIPTION

[0023] The following examples further illustrate the present application but should not be construed as limiting. Modifications and adaptations of the methods, steps or conditions described may be employed as appropriate and should be understood to fall within the scope of the present application.

[0024] DETAILED DESCRIPTION

[0025] I. Preparation of metal salt solution:

[0026] Dissolve divalent metal salt and trivalent metal salt into water to obtain metal salt solution;

[0027] II. Preparation of mixed solution of sodium hydroxide and sodium carbonate:

[0028] Dissolve sodium hydroxide and sodium carbonate into water to obtain mixed solution of sodium hydroxide and sodium carbonate;

[0029] III. Under stirring, drop mixed solution of sodium hydroxide and sodium carbonate into metal salt solution until pH value of metal salt solution is 10 to obtain gel;

[0030] IV. Age the gel, then wash with deionized water, dry and finally grind to obtain layered hydrotalcite material;

[0031] V. Add layered hydrotalcite material and peracetic acid into wastewater containing endocrine disruptor, adjust pH value of wastewater to 3-9, degrade endocrine disruptor under stirring to complete the method.

[0032] Embodiment two: the difference between this embodiment and embodiment one is that the divalent metal salt in step one is copper nitrate, basic copper carbonate, zinc nitrate, cobalt nitrate or magnesium nitrate. The other steps are the same as embodiment one.

[0033] Embodiment three: the difference between this embodiment and either embodiment one or two is that the trivalent metal salt in step one is aluminum nitrate, aluminum chloride or ferric nitrate. The other steps are the same as embodiment one or two.

[0034] Embodiment four: the difference between this embodiment and any one of embodiments one to three is that the molar ratio of the divalent metal salt to the trivalent metal salt in step one is (1-3): 1; and the volume ratio of the divalent metal salt to water in step one is (50 mmol-200 mmol):(100 mL-400 mL). The other steps are the same as embodiments one to three.

[0035] Embodiment five: the difference between this embodiment and any one of embodiments one to four is that the molar ratio of sodium hydroxide to sodium carbonate in step two is 1:(1-2); and the concentration of sodium hydroxide in the mixed solution of sodium hydroxide and sodium carbonate in step two is 0.2 mol / L-1.0 mol / L. The other steps are the same as embodiments one to four.

[0036] Embodiment six: the difference between this embodiment and any one of embodiments one to five is that the temperature of aging in step four is 60°C-100°C, and the aging time is 20 h-24 h. The other steps are the same as embodiments one to five.

[0037] Embodiment seven: the difference between this embodiment and any one of embodiments one to six is that the washing in step four is performed 3-5 times with deionized water, and then drying is performed at 40°C-60°C for 10 h-14 h, and finally grinding is performed to obtain the layered hydrotalcite material. The other steps are the same as embodiments one to six.

[0038] Embodiment eight: the difference between this embodiment and any one of embodiments one to seven is that the endocrine disruptor in the wastewater containing endocrine disruptors in step five is bisphenol A, alkylphenol, alkylphenol polyoxyethylene ether, phthalate, polychlorinated biphenyl or 17α-ethinyl estradiol. The other steps are the same as embodiments one to seven.

[0039] Specific embodiment nine: the difference between this embodiment and one of the specific embodiments one to eight is that the mass of the layered hydrotalcite material to the volume of the wastewater in step five is (0.02g-0.5g):1L; the amount of substance of the peroxoacetic acid to the volume of the wastewater in step five is (0.50mmol-2mmol):1L. The other steps are the same as specific embodiments one to eight.

[0040] Specific embodiment ten: the difference between this embodiment and one of the specific embodiments one to nine is that the speed of the stirring in step five is 380r / min-550r / min; the degradation time in step five is 10min-45min; the concentration of the endocrine disruptors in the wastewater containing endocrine disruptors in step five is 10mg / L-50mg / L. The other steps are the same as specific embodiments one to nine.

[0041] The following examples are used to verify the beneficial effects of the present application:

[0042] Example 1: a method for treating endocrine disruptors in water by layered hydrotalcite material catalyzed peroxoacetic acid, which is completed according to the following steps:

[0043] I. Preparation of metal salt solution:

[0044] 100mmol of copper nitrate trihydrate and 50mmol of aluminum nitrate nonahydrate are dissolved in 400mL of water to obtain a metal salt solution;

[0045] II. Preparation of sodium hydroxide and sodium carbonate mixed solution:

[0046] Sodium hydroxide and sodium carbonate are dissolved in water to obtain a sodium hydroxide and sodium carbonate mixed solution;

[0047] The molar ratio of sodium hydroxide to sodium carbonate in step two is 1:2; the concentration of sodium hydroxide in the sodium hydroxide and sodium carbonate mixed solution in step two is 0.2mol / L;

[0048] III. Under stirring conditions, the sodium hydroxide and sodium carbonate mixed solution is added dropwise to the metal salt solution until the pH value of the metal salt solution is 10 to obtain a gel;

[0049] IV. The gel is aged at 80℃ for 24h, then washed with deionized water for 3 times, finally dried at 40℃ for 12h, and finally ground to obtain Cu-Al LDH;

[0050] V. Cu-Al LDH and peracetic acid were added into the wastewater containing bisphenol A, the pH value of the wastewater was adjusted to 7, bisphenol A was degraded under stirring condition, the degradation time was 45 min, samples were taken at certain time interval and filtered, the content of peracetic acid and bisphenol A in the samples was determined by spectrophotometer;

[0051] The mass / volume ratio of Cu-Al LDH to wastewater in step V was 0.1 g:1 L;

[0052] The amount of substance / volume ratio of peracetic acid to wastewater in step V was 2 mmol:1 L;

[0053] The stirring speed in step V was 400 r / min;

[0054] The concentration of bisphenol A in the wastewater containing bisphenol A in step V was 20 mg / L.

[0055] Example 2: The difference between this example and Example 1 is that the mass / volume ratio of Cu-Al LDH to wastewater in step V is 0.25 g:1 L. The other steps and parameters are the same as those in Example 1.

[0056] Example 3: The difference between this example and Example 1 is that the mass / volume ratio of Cu-Al LDH to wastewater in step V is 0.05 g:1 L. The other steps and parameters are the same as those in Example 1.

[0057] Figure 1 The degradation curve of Cu-Al LDH prepared in different examples 1-3 catalyzing peracetic acid to degrade bisphenol A is shown in the figure, wherein 1 is Example 3, 2 is Example 1, and 3 is Example 2;

[0058] From Figure 1 It can be seen that the concentration of Cu-Al LDH (catalyst) is low, the combination probability of peracetic acid and active sites is small in the reaction process, the generated free radicals are less, and the degradation rate is inhibited. The degradation efficiencies under the conditions of Examples 1, 2 and 3 are compared, which shows that the more Cu-Al LDH (catalyst) is added, the better the catalytic degradation effect is.

[0059] Example 4: The difference between this example and Example 1 is that the pH value of the wastewater is adjusted to 3 in step V. The other steps and parameters are the same as those in Example 1.

[0060] Example 5: The difference between this example and Example 1 is that the pH value of the wastewater is adjusted to 9 in step V. The other steps and parameters are the same as those in Example 1.

[0061] Figure 2The degradation curves of bisphenol A by Cu-AlLDH-catalyzed peracetic acid under different pH conditions are shown in the figures. In the figures, 1 represents Example 1, 2 represents Example 5, and 3 represents Example 4.

[0062] from Figure 2 It can be seen that at pH=9, the catalytic degradation rate of bisphenol A by peracetic acid is relatively low, due to the presence of OH- in the solution. - It interacts with free radicals and inhibits their oxidative activity. Figure 2 The removal efficiency of Examples 1, 4, and 5 is compared, and the catalytic degradation effect is the best at pH=7.

[0063] Example 6: The difference between this example and Example 1 is that in step one, 50 mmol of copper nitrate trihydrate and 50 mmol of aluminum nitrate nonahydrate were dissolved in 400 mL of water to obtain a metal salt solution. All other steps and parameters are the same as in Example 1.

[0064] Figure 3 The degradation curves of bisphenol A by peracetic acid catalyzed by Cu-AlLDH prepared in Examples 1 and 6 are shown in Figure 1 and Figure 2, respectively.

[0065] from Figure 3 It can be seen that when the molar ratio of copper nitrate trihydrate to aluminum nitrate nonahydrate is 1:1, the number of catalytically active sites (Cu) is less than that when the molar ratio is 2:1. Therefore, peracetic acid has fewer binding sites with the catalyst, resulting in lower catalytic efficiency.

[0066] Example 7: Peracetic acid was added to wastewater containing bisphenol A, the pH of the wastewater was adjusted to 7, and bisphenol A was degraded under stirring conditions for 45 minutes. Samples were taken at certain time intervals and filtered. The contents of peracetic acid and bisphenol A in the samples were determined by spectrophotometer.

[0067] The amount of peracetic acid mentioned in step five is in a volume ratio of 2 mmol: 1 L to wastewater.

[0068] The stirring speed described in step five is 400 r / min;

[0069] The concentration of bisphenol A in the wastewater containing bisphenol A mentioned in step five is 20 mg / L.

[0070] Example 8: Cu-AlLDH prepared in Example 1 was added to wastewater containing bisphenol A, the pH of the wastewater was adjusted to 7, and bisphenol A was degraded under stirring conditions for 45 min. Samples were taken at certain time intervals and filtered. The bisphenol A content in the samples was determined by spectrophotometer.

[0071] The mass of Cu-Al LDH described in step five to the volume ratio of wastewater is 0.1 g:1 L;

[0072] The stirring speed described in step five is 400 r / min;

[0073] The concentration of bisphenol A in the wastewater containing bisphenol A described in step five is 20 mg / L.

[0074] Figure 4 The degradation curve of bisphenol A in examples 1, 7 and 8.

[0075] Without Cu-Al LHD activation, peracetic acid generates few free radicals, and the efficiency of peracetic acid itself acting on pollutants is low, so the degradation efficiency of bisphenol A is low without Cu-Al LHD; without peracetic acid, Cu-Al LHD only acts as an adsorbent and cannot activate oxidants to generate free radicals, and the adsorption alone cannot achieve a good removal effect, so the removal efficiency of bisphenol A is low.

[0076] From Figure 4 It can be seen that the degradation efficiency is low under the conditions of Cu-Al LHD alone and peracetic acid alone, and the coupling of Cu-Al LHD and peracetic acid can greatly improve the degradation effect and removal speed of pollutants, so this method achieves the purpose of efficiently removing endocrine disruptors.

Claims

1. A method for the catalytic peroxi-acetic acid treatment of endocrine disruptors in water using a layered hydrotalcite material, characterized in that The method can degrade 100% of the endocrine disruptor bisphenol A in water within 30 minutes, and the method is completed by the following steps: I. Preparation of metal salt solution: Dissolve 100 mmol of copper nitrate trihydrate and 50 mmol of aluminum nitrate nonahydrate into 400 mL of water to obtain a metal salt solution; II. Preparation of sodium hydroxide and sodium carbonate mixed solution: Dissolve sodium hydroxide and sodium carbonate into water to obtain a sodium hydroxide and sodium carbonate mixed solution; The molar ratio of sodium hydroxide to sodium carbonate in step II is 1:2; the concentration of sodium hydroxide in the sodium hydroxide and sodium carbonate mixed solution in step II is 0.2 mol / L; III. Under stirring, add the sodium hydroxide and sodium carbonate mixed solution into the metal salt solution until the pH value of the metal salt solution is 10 to obtain a gel; IV. Age the gel at 80°C for 24 h, then wash it with deionized water for 3 times, finally dry it at 40°C for 12 h, and finally grind it to obtain Cu-Al LDH; V. Add Cu-Al LDH and peroxyacetic acid into wastewater containing bisphenol A, adjust the pH value of the wastewater to 7, degrade bisphenol A under stirring, the degradation time is 45 min, take samples at certain time intervals, filter the samples, and determine the contents of peroxyacetic acid and bisphenol A in the samples by spectrophotometry; The mass of Cu-Al LDH to the volume of wastewater in step V is 0.25 g:1 L; The amount of substance of peroxyacetic acid to the volume of wastewater in step V is 2 mmol:1 L; The stirring speed in step V is 400 r / min; The concentration of bisphenol A in the wastewater containing bisphenol A in step V is 20 mg / L.

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