A method for catalytic oxidation degradation of organic / inorganic wastewater by hypochlorite using a calcium-iron-aluminum composite catalytic material

Abstract

The present invention discloses a method for catalytic oxidation degradation of organic / inorganic wastewater by a calcium-iron-aluminum composite catalytic material and hypochlorite, belonging to the technical field of wastewater treatment. This method is to add the calcium-iron-aluminum composite catalytic material and hypochlorite into organic wastewater and / or inorganic wastewater for catalytic oxidation reaction. Among them, the calcium-iron-aluminum composite catalytic material is obtained by hydrolysis co-precipitation method from calcium salt, iron salt and aluminum salt. The calcium-iron-aluminum composite catalytic material used in this method has good stability in the hypochlorite system, can be reused repeatedly for many times and has a long service life. At the same time, it has high catalytic activity, and shows good adsorption effect, fast oxidation degradation rate, thorough oxidation degradation and high hypochlorite utilization rate for difficult-to-oxidize and degrade organic matters, ammonia nitrogen, metal complexes, etc. in organic / inorganic wastewater, and can effectively solve the technical problems existing in the application of hypochlorite oxidation to the oxidation degradation of organic / inorganic wastewater.

Description

Technical Field

[0001] The present invention relates to a method for oxidatively degrading organic / inorganic wastewater, and particularly to a method for catalytically oxidizing and degrading organic / inorganic wastewater by hypochlorite using a calcium-iron-aluminum composite catalytic material, belonging to the technical field of wastewater treatment. Background Art

[0002] In recent years, with the rapid development of industrial technologies, while bringing huge economic benefits, many environmental pollution problems have also been brought, posing a serious threat to human health and the ecosystem. Currently, for various (high-salt) refractory organic or inorganic wastewater, advanced oxidation methods are usually used for treatment. Commonly used advanced oxidation methods include photocatalytic oxidation, electrochemical oxidation, persulfate oxidation, ozone oxidation, Fe(III) displacement / UV oxidation, and Fenton oxidation. For example: The literature (He Sitong. Research on the effect and mechanism of photocatalytic degradation of Cu-EDTA by iron-based MOFs [D]. Northwest A&F University, 2021.) discloses the photocatalytic degradation of EDTA-Cu using iron-based MOFs. Under the irradiation of UV, when the pH is 2.0 and 8.0, the degradation rates of EDTA-Cu after 120 min are 99% and 57% respectively. The removal rate of the material decreases to less than 80% during the second repetition, and the dissolution of Fe in the material is 5.15 mg / L. The literature (Ye Xiaokun, Zhang Junya, Zhang Yan, et al. Treatment of Ni-EDTA containing wastewater by electrocoagulation using iron scraps packed-bed anode [J]. Chemosphere, 2016, 164: 304-313.) discloses the optimization of the removal of EDTA-Ni in wastewater by applying a new electrocoagulator with an iron scrap packed-bed anode. Under the optimal conditions, the removals of metal and TOC can reach 94.3% and 95.79% respectively, and the optimal reaction temperature is about 313K. However, the final residual content of the metal is 1.93 mg / L, and the released Fe content is 357.85 mg / L. The literature (Xu Zhe, Wu Tiancheng, Cao Yu, et al. Efficient decomplexation of heavy metal-EDTA complexes by Co 2+ / Peroxymonosulfate process: The critical role of replacement mechanism[J]. Chemical Engineering Journal, 2020, 392. It was reported that the Co(II) / peroxymonosulfate (PMS) system was used to remove EDTA metal complexes. When the concentration of Co(II) was 10 ppb, about 90% of Cu ions were released within 120 min, and the concentration of Co(II) after the reaction was lower than the wastewater discharge standard of 1.0 mg / L. However, the presence of EDTA would inhibit the catalytic effect of Co(II). The literature (Li Tong, Bian Haokun, Wang Wei, et al. Removal of low-concentration nickel in electroplating wastewater via incomplete decomplexation by ozonation and subsequent resin adsorption[J]. Chemical Engineering Journal, 2022, 435.) reported that a method of ozone oxidation for breaking the complex combined with resin adsorption was used to treat low-concentration nickel-containing wastewater. The low-concentration nickel-containing wastewater was treated with 8 mg / L ozone, resulting in the breaking of the complex of heavy metals. Then, cation exchange resin was used to adsorb and recover heavy metals in actual electroplating wastewater, and finally the relevant discharge standards were achieved. The literature (Zhu Ying, Fan Wenhong, Feng Weiying, et al. Removal of EDTA-Cu(II) from Water Using Synergistic Fenton Reaction-Assisted Adsorption by Nanomanganese Oxide-Modified Biochar: Performance and Mechanistic Analysis[J]. ACS ES&T Water, 2021, 1(5): 1302-1312.) reported that nanomanganese oxide-modified biochar was used in combination with the Fenton reaction to remove 100 mg / L of EDTA-Cu. When the concentration of H 2 O 2 was 4 mol / L, the removal rate of Cu could reach more than 95%. The influence of pH from 4 to 10 was also investigated, and it was found that the removal effect varied greatly in different pH environments. The removal effect of the prepared modified material would be less than 90% after the second repetition.

[0003] Hypochlorite oxidation is a new environmentally friendly advanced oxidation technology, which has the advantages of strong oxidizing property, wide reaction pH range, high efficiency and economy, and is thus widely used in the degradation of organic substances and the removal of heavy metals. However, the generation rate of its active substances is not high, and the instability of its properties will also lead to natural decomposition and reduce the generation of active substances. Therefore, it is necessary to add exogenous substances or energy supply to accelerate the generation rate of active substances during the reaction. For example (Guo X, Chen S, Liu Z, et al. Catalytic oxidation of methylene blue by using Ni-Fe bimetallic catalyst / NaClO system: Performance, kinetics, mechanism, and DFT calculations [J]. Separation and Purification Technology, 2023, 306: 122612.) discloses the preparation of a nickel-iron bimetallic catalyst (Ni-Fe / Al 2 O 3 ) supported on activated alumina by the impregnation pyrolysis method for catalytic oxidation degradation of methylene blue (MB) by sodium hypochlorite (NaClO). The removal rate of MB can reach 98.98% within 40 min, but this catalyst uses heavy metal nickel as the active component. Summary of the Invention

[0004] Aiming at the technical problems such as poor catalytic oxidation effect and poor stability of catalytic materials when the existing hypochlorous acid oxidation technology is applied to the removal of pollutants in organic or inorganic wastewater, the purpose of the present invention is to provide a method for catalytic oxidation degradation of organic or inorganic wastewater by a calcium-iron-aluminum composite catalytic material. The calcium-iron-aluminum composite catalytic material used in this method has good stability in the hypochlorite system, can be reused repeatedly, has a long service life, and at the same time has high catalytic activity, showing good adsorption effect, fast oxidation degradation rate, thorough oxidation degradation, and high utilization rate of hypochlorite for the degradation of refractory pollutants in organic or inorganic wastewater, etc., and can effectively solve the technical problems existing in the oxidation degradation of electroplating wastewater by hypochlorite.

[0005] To achieve the above technical purpose, the present invention provides a method for catalytic oxidation degradation of organic / inorganic wastewater by a calcium-iron-aluminum composite catalytic material, which is to add the calcium-iron-aluminum composite catalytic material and hypochlorite into organic wastewater and / or inorganic wastewater for catalytic oxidation reaction; the calcium-iron-aluminum composite catalytic material is obtained by hydrolysis co-precipitation of calcium salt, iron salt and aluminum salt.

[0006] The key of the present invention lies in the use of a special calcium-iron-aluminum composite catalytic material for catalyzing the generation of 1 O2 to promote the oxidative degradation of organic or inorganic pollutants. The calcium-iron-aluminum composite catalytic material is prepared by adopting a Ca and Al doping strategy. Through the coprecipitation method, the doping of Ca and Al is realized, which changes the agglomeration effect of ferrihydrite, provides open channels and reaction sites, replaces the bond positions of some Fe elements with Ca and Al elements, forms relatively stable chemical bonds with O, and generates abundant oxygen vacancies (OVs) on the surface of the composite catalytic material, thereby promoting the improvement of the catalytic performance of the composite catalytic material. The oxygen vacancies (OVs) induced by Ca and Al doping can enhance the electron transfer ability and provide abundant surface adsorption sites, thereby promoting the production of reactive oxygen species by hypochlorite. - In the reaction process of catalytic oxidation to remove organic or inorganic pollutants, reactive oxygen species (singlet oxygen ( 1 O 2 )) play a major role, and among them, 1 O 2 is formed from the electrons provided by the composite catalytic material and the ClO - oxidation system. The generated singlet oxygen plays a key role in the oxidative degradation of organic or pollutants. In particular, the doping of aluminum greatly improves the stability of the calcium-iron-aluminum composite catalytic material, and its chemical stability in the hypochlorite oxidation system is greatly improved, which is beneficial to improving its cycle stability.

[0007] As a preferred embodiment, the calcium-iron-aluminum composite catalytic material is prepared by the following method: Dissolve calcium salt, iron salt and aluminum salt in water according to a molar ratio of (1-5):1:(0.5-2.5), then add a strong base solution to carry out a hydrolysis coprecipitation reaction, and the obtained precipitate product is successively subjected to centrifugal separation, washing, drying and grinding to obtain the product. As the molar ratio of aluminum salt and calcium salt relative to iron salt increases, the catalytic activity of the calcium-iron-aluminum composite catalytic material increases significantly. When the molar ratio of aluminum salt and calcium salt relative to iron salt is increased to 1:4 and 1:1.5 respectively, the catalytic activity of the calcium-iron-aluminum composite catalytic material tends to be stable. Therefore, the molar ratio of calcium salt, iron salt and aluminum salt of (3-5):1:(1-2.5) is further preferred. Preferred calcium salts are one or more of calcium nitrate, calcium hypochlorite, and calcium chloride. Preferred iron salts are one or more of ferric chloride, ferric sulfate, and ferric nitrate. Preferred aluminum salts are one or more of aluminum nitrate, aluminum sulfate, and calcium aluminum chloride.

[0008] As a preferred embodiment, the total mass percentage concentration of the calcium salt, iron salt and aluminum salt in water is 1-30%.

[0009] As a preferred embodiment, the conditions for the hydrolysis co-precipitation reaction are as follows: adding a strong base solution to maintain the pH at 7-11, stirring and reacting at 5-40 °C for 0.5-3 h. Further preferably, the pH of the hydrolysis precipitation reaction is 9-11. Further preferably, the temperature of the hydrolysis co-precipitation reaction is 15-25 °C. Temperature and pH have relatively greater effects on the catalytic activity of the calcium-iron-aluminum composite catalytic material. The higher the pH and the closer the temperature is to room temperature, the more favorable it is.

[0010] As a preferred embodiment, the organic wastewater includes at least one of metal complex wastewater, printing and dyeing wastewater, antibiotic wastewater, landfill leachate, and pesticide wastewater.

[0011] As a preferred embodiment, the inorganic wastewater includes at least one of ammonia nitrogen wastewater and heavy metal wastewater.

[0012] As a preferred embodiment, the dosage of the calcium-iron-aluminum composite catalytic material in the organic wastewater or inorganic wastewater is adjusted within the range of 0.1-4 g / L according to the content of the pollutants to be oxidized and degraded in the organic wastewater or inorganic wastewater.

[0013] As a preferred embodiment, the dosage of the hypochlorite in the organic wastewater or inorganic wastewater is adjusted within the range of 0.1-20 g / L according to the content of the pollutants to be oxidized and degraded in the organic wastewater or inorganic wastewater.

[0014] It is well-known to those skilled in the art that the dosages of the calcium-iron-aluminum composite catalytic material and hypochlorite in the organic or inorganic wastewater of the present invention are determined according to the content of the pollutants to be oxidized and degraded in the organic wastewater or inorganic wastewater. The higher the content of organic pollutants, the higher the corresponding dosages of the calcium-iron-aluminum composite catalytic material and hypochlorite. The hypochlorite mainly provides hypochlorite ions. In theory, any hypochlorite that can release hypochlorite ions can be used. However, preferably, its effective chlorine mass content is greater than 8%.

[0015] As a preferred embodiment, the conditions for the oxidation reaction are as follows: the temperature is 10-40 °C, the time is more than 1 hour, and the pH is 5-11. Under alkaline conditions, it is more beneficial to improve the catalytic activity of the calcium-iron-aluminum composite catalytic material for generating 1 O 2 active substances. Further preferably, the pH is 9-11.

[0016] The calcium-iron-aluminum composite catalytic material involved in the present invention is prepared by the existing hydrolysis co-precipitation method, including the following steps:

[0017] (1) Add Ca salt, Fe salt and Al salt to distilled water according to the molar ratio of calcium salt, iron salt and aluminum salt (1-5):1:(0.5-2.5), and stir to obtain solution A with a mass concentration of 1-30%. Slowly add NaOH solution to solution A during stirring until a stable pH of 7-11 is reached, and continuously stir at a temperature of 5-40 °C for 0.5-3 hours to obtain solution B;

[0018] (2) Put the solution B obtained in step (1) into a centrifuge with a centrifugal speed of 5000-15000 r / min to obtain precipitate C;

[0019] (3) Wash the precipitate C obtained in step (2) with distilled water and anhydrous alcohol solution multiple times to obtain precipitate D; the anhydrous alcohol solution is anhydrous ethanol, anhydrous propanol, etc.;

[0020] (4) Put the precipitate D obtained in step (3) into a vacuum drying oven for constant temperature drying. The drying temperature is 50-100 °C and the drying time is 10-30 h to obtain dry solid E;

[0021] (5) Grind the solid E obtained in step (4) into powder to obtain a calcium-iron-aluminum composite catalytic material.

[0022] Compared with the prior art, the beneficial technical effects brought by the technical solution of the present invention are:

[0023] 1) The present invention uses a calcium-iron-aluminum composite catalytic material to catalyze the oxidation and degradation of organic or inorganic wastewater, especially for the difficult-to-oxidize and degrade pollutants in organic or inorganic wastewater, such as EDTA complexes of transition metals, ammonia nitrogen, tetraaminopyridine, etc. It has the characteristics of fast oxidation and degradation rate, complete oxidation and degradation, high utilization rate of hypochlorite, etc., and can effectively solve the technical problems existing in the application of hypochlorite in the oxidation and degradation of organic or inorganic wastewater.

[0024] 2) The calcium-iron-aluminum composite catalytic material adopted by the present invention has good chemical stability. Especially in the hypochlorite oxidation system, the material structure is stable and can be reused multiple times, and the reuse effect is good, reducing the use cost of the catalyst.

[0025] 3) The calcium-iron-aluminum composite catalytic material adopted by the present invention can be regulated by changing the doping amounts of calcium, aluminum and iron elements. When the calcium-iron-aluminum molar ratio is 4:1:2, the catalytic degradation effect of the calcium-iron-aluminum composite catalytic material is better. Description of the Drawings

[0026] Figure 1 It is a preparation flow chart of the calcium-iron-aluminum composite catalytic material of the present invention.

[0027] Figure 2Comparison chart of the oxidation degradation efficiency of calcium-iron-aluminum composite catalytic materials prepared under different conditions in Examples 3-6.

[0028] Figure 3 Adsorption removal rate and catalytic oxidation removal rate of pollutants by the calcium-iron-aluminum composite catalytic material prepared in Example 1 at different pH values.

[0029] Figure 4 Oxidation degradation effect of pollutants by calcium-iron-aluminum composite catalytic materials with different aluminum doping amounts prepared in Example 2.

[0030] Figure 5 Oxidation degradation effect of pollutants by the calcium-iron-aluminum composite catalytic material prepared in Example 1 at different catalyst dosages.

[0031] Figure 6 Free radical shielding result chart of the calcium-iron-aluminum composite catalytic material of the present invention.

[0032] Figure 7 SEM image of the calcium-iron-aluminum composite catalytic material prepared in Example 1 at 1 μm.

[0033] Figure 8 SEM image of the calcium-iron-aluminum composite catalytic material prepared in Example 1 at 10 μm.

[0034] Figure 9 Infrared spectrum chart comparing the calcium-iron-aluminum composite catalytic material prepared in Example 1 with calcium-iron composite catalytic material and iron catalytic material.

[0035] Figure 10 and Figure 11 Free radical EPR test spectrum of the calcium-iron-aluminum composite catalytic material prepared in Example 1.

[0036] Figure 12 XRD test spectrum of the calcium-iron-aluminum composite catalytic material of Example 1.

[0037] Figure 13 Repeatability test of different aluminum contents of the calcium-iron-aluminum composite catalytic material of Example 1. Detailed implementation mode

[0038] The present invention will be further described below. It should be noted that this embodiment is based on the present technical solution, and detailed implementation modes and specific operation processes are given, but the present invention is not limited to this embodiment.

[0039] Example 1

[0040] (1) Calcium nitrate, calcium chloride, and aluminum chloride were added to distilled water and stirred to obtain solution A. The total concentration of metal ions in the solution was 1 mol / L. Among them, the molar ratio of calcium, iron, and aluminum elements in solution A was 4:1:2. During the stirring of solution A, NaOH solution was added to stabilize the pH at 11 and continuously stirred at 20 °C for 2 hours to obtain solution B, where the solution was a homogeneous suspension;

[0041] (2) The solution B obtained in step (1) was washed with distilled water and anhydrous ethanol multiple times, and the precipitate C was collected by centrifugation at 10000 r / min;

[0042] (3) The precipitate C obtained in step (2) was placed in a vacuum drying oven and dried at a constant temperature of 60 °C for 12 hours to obtain the dried solid D. The color of the dried solid D was a reddish-brown solid;

[0043] (4) The solid D obtained in step (3) was ground into powder to obtain the calcium-iron-aluminum composite catalytic material.

[0044] (5) The calcium-iron-aluminum composite catalytic material was applied to degrade electroplating wastewater with EDTA-Cu of 20 mg / L. The concentration of complexed copper (calculated as Cu 2+ ) was 20 mg / L. The addition amount of the calcium-iron-aluminum composite catalytic material was 0.5 g / L, and the addition amount of sodium hypochlorite solution with a concentration of 1 mol / L was 2 mL / L. The conditions for oxidative degradation were: temperature at room temperature, time 1 hour, and pH 11.

[0045] Various tests were carried out on the calcium-iron-aluminum composite catalytic material prepared in Example 1.

[0046] From Figure 7 and Figure 8 of the electron microscope images, it can be seen that the prepared calcium-iron-aluminum composite catalytic material is a layered block structure, and the aluminum element doping shows a cubic morphology with a single particle diameter of about 500 nm.

[0047] From Figure 9 it can be seen that when calcium and aluminum elements were not doped, among them, the absorption peak near 620 cm -1 was generated by the stretching vibration of the Fe-O bond, and the absorption peaks near 796 and 887 cm -1 were generated by the stretching vibration of the Fe-O-H bond; the absorption peak appearing near 1638 cm -1 was the H-O-H deformation vibration peak, and the bands of 3426, 1635, and 1350 cm -1 were related to the stretching vibration of surface hydroxyl groups, the -OH vibration of adsorbed water, and the bending vibration of Fe-O-H respectively. The 3110 cm -1The absorption peaks that appear nearby are the stretching vibration peaks of -OH. When Ca is incorporated, the absorption peaks at 890 and 790 cm-1 are due to the breaking of the Fe-O-H bond position caused by the incorporation of Ca, while the absorption peak at 591.2 cm -1 The change in the absorption peak nearby can be attributed to the formation of the Ca-O bond. When Al is incorporated, an in-plane bending vibration of Al-O appears at 1023.6 cm -1 and the waveband at 535.4 cm -1 is caused by the characteristic absorption of [Al 2 O(OH) 6 2 . It shows that the functional groups on the material surface have been substituted during the reaction, thereby improving the surface stability of the material.

[0048] The calcium-iron-aluminum composite catalyst prepared in Example 1 was applied to the oxidation degradation of electroplating wastewater with EDTA-Cu of 20 mg / L. The concentration of complexed copper (calculated as Cu 2+ ) was 20 mg / L, Figure 3 shows the adsorption effect and catalytic oxidation removal effect of the calcium-iron-aluminum catalytic material on complexed copper at different pH values (other conditions in the oxidation degradation process are as described in step (5) above). It can be seen from Figure 3 that there is a good removal effect at pH = 5 - 11, and the adsorption and removal effect of the catalyst on complexed copper is enhanced in the alkaline environment. Figure 4 shows the adsorption effect and catalytic oxidation removal effect of the calcium-iron-aluminum catalytic materials prepared with different aluminum doping amounts on complexed copper (the conditions in the oxidation degradation process are as described in step (5) above). It can be seen from Figure 4 that when the molar ratio of calcium-iron-aluminum is 4:1:2, the prepared calcium-iron-aluminum composite catalytic material has a better oxidation degradation and removal effect on complexed copper, and the removal rate of complexed copper approaches 100% within two hours. Figure 5 shows the degradation effect of the calcium-iron-aluminum composite catalytic material on pollutants under different catalyst dosages. It can be seen from Figure 5 that as the amount of the calcium-iron-aluminum composite catalytic material increases, the oxidation degradation and removal effect of the calcium-iron-aluminum composite catalytic material on complexed copper is better.

[0049] Example 1 was applied to the removal experiment of complexed copper. Before the degradation experiment, the same concentration of scavengers was added to the solution. The scavengers were ascorbic acid (ROS spectrum scavenger), L-histidine ( 1 O 2 scavenger), methanol (·OH scavenger), tert-butanol (·OH and Cl· scavenger), p-benzoquinone (·O 2 - scavenger), and one of them was selected. It can be seen from Figure 6 ​It can be seen that when L-histidine, ascorbic acid, and p-benzoquinone are added during the degradation experiment, the degradation of complexed copper is significantly inhibited, while other scavengers do not have an obvious effect. Therefore, 1 O 2 is the main active substance in the experimental system. The EPR test was carried out using the calcium-iron-aluminum composite catalytic material prepared in Example 1, and the test results are shown in Figure 10 , and from Figure 10 it can be seen that when the TEMP scavenger is used without adding the calcium-iron-aluminum composite catalytic material, no 1:1:1 signal peak appears, and when the TEMP is used after adding the calcium-iron-aluminum composite catalytic material, a 1:1:1 signal peak appears, indicating that 1 O 2 is the main active substance in the experimental system, which is consistent with the results of the scavenging experiment. Through Figure 11 it can be seen that the signal near g = 2.004 is attributed to the generation of oxygen vacancies, indicating that Fe-Ca-Al contains a large number of oxygen vacancies, which promotes the generation of singlet oxygen and improves the catalytic effect.

[0050] In order to explore the influence of Ca and Al element doping on the physicochemical properties of the composite catalytic material, the crystal structure change of the composite catalytic material after the addition of Ca and Al elements was studied by X-ray diffraction (XRD). The XRD energy spectra of the composite catalytic material before and after Ca and Al element doping showed diffraction patterns similar to those of ferrihydrite, indicating that the addition of Ca and Al elements did not change the original crystal structure of the composite catalytic material. Through Figure 12 it can be seen that the peaks at 2θ of 17.8°, 21.2°, and 26.3° correspond to Fe-OH (PDF#99-0055) on its (020), (110), and (120) crystal planes, and the peaks at 2θ of 35.5° and 57.4° correspond to Fe-O (PDF#99-0060) on its (110) and (112) crystal planes. The diffraction peaks at 32.2° (PDF#99-0070) belong to the Ca-O (110) crystal plane respectively, and the peaks at 2θ of 27.8° and 45.7° correspond to Al-OH (PDF#99-0017) on its (111) and (211) crystal planes, and the peaks at 2θ of 17.8° and 37.2° correspond to Al-O (PDF#99-0036) on its (020), (110), and (120) crystal planes. The enhancement of the peak intensity indicates that the crystallinity and particle size increase due to the incorporation of Ca and Al. After the incorporation of Ca and Al elements, they replace some Fe positions and form new bond positions with O, increasing the crystallinity of this crystal plane and improving the particle size of the material. Therefore, the doping of Ca and Al elements basically does not damage the original crystal structure, and the enhancement and weakening of the diffraction peaks are only due to the stacking and impact of the incorporated Ca and Al elements on a certain crystal plane. In addition, the weakening of the diffraction peak may also be due to the formation of smaller microcrystals.

[0051] Example 2

[0052] The difference between Example 2 and Example 1 is that the molar ratios of calcium element, iron element, and aluminum element are 4:1:0.5, 4:1:0, 4:1:1, 4:1:1.5, 4:1:2.5, 4:1:3 respectively, and Example 1 is used as a comparison.

[0053] The calcium-iron-aluminum composite catalytic material was applied to degrade electroplating wastewater with 20 mg / L of EDTA-Cu, the concentration of complexed copper (calculated as Cu 2+ is) 20 mg / L, the addition amount of the calcium-iron-aluminum composite catalytic material is 0.5 g / L, the addition amount of the sodium hypochlorite solution with a concentration of 1 mol / L is 2 mL / L, and the conditions for oxidative degradation are: the temperature is room temperature, the time is 1 hour, and the pH is 11. The results are shown in Figure 4 .

[0054] In addition, by recycling the calcium-iron-aluminum composite catalytic material and referring to the above degradation process for cyclic use, the cyclic use effect is shown in Figure 13 . With the increase of the doping amount of aluminum, its chemical stability is significantly improved, and when the molar ratio of calcium element, iron element, and aluminum element is 4:1:2, the cyclic use effect reaches the best.

[0055] Example 3

[0056] The difference between Example 3 and Example 1 is that: the molar ratios of calcium element, iron element, and aluminum element are replaced by 1:1:2, 2:1:2, 3:1:2, 5:1:2 respectively, and 4:1:2 in Example 1 is used as a comparison. The calcium-iron-aluminum composite catalytic material was applied to degrade electroplating wastewater with 20 mg / L of EDTA-Cu, the concentration of complexed copper (calculated as Cu 2+ is) 20 mg / L, the addition amount of the calcium-iron-aluminum composite catalytic material is 0.5 g / L, the addition amount of the sodium hypochlorite solution with a concentration of 1 mol / L is 2 mL / L, and the conditions for oxidative degradation are: the temperature is room temperature, the time is 1 hour, and the pH is 11. The results are shown in Figure 2 .

[0057] Example 4

[0058] The difference between Example 4 and Example 1 is that: the reaction pH is replaced by 7 and 9 respectively, and 11 in Example 1 is used as a comparison. The calcium-iron-aluminum composite catalytic material was applied to degrade electroplating wastewater with 20 mg / L of EDTA-Cu, the concentration of complexed copper (calculated as Cu 2+ is) 20 mg / L, the addition amount of the calcium-iron-aluminum composite catalytic material is 0.5 g / L, the addition amount of the sodium hypochlorite solution with a concentration of 1 mol / L is 2 mL / L, and the conditions for oxidative degradation are: the temperature is room temperature, the time is 1 hour, and the pH is 11. The results are shown in Figure 2 .

[0059] Example 5

[0060] The difference between Example 5 and Example 1 is that the reaction temperatures are replaced with 40°C and 60°C respectively, and compared with 20°C in Example 1. The calcium-iron-aluminum composite catalytic material is applied to degrade electroplating wastewater with 20 mg / L of EDTA-Cu. The concentration of complexed copper (calculated as Cu 2+ is 20 mg / L. The addition amount of the calcium-iron-aluminum composite catalytic material is 0.5 g / L, and the addition amount of sodium hypochlorite solution with a concentration of 1 mol / L is 2 mL / L. The conditions for oxidative degradation are: temperature is room temperature, time is 1 hour, and pH is 11. The results are shown in Figure 2 .

[0061] Example 6

[0062] The difference between Example 6 and Example 1 is that the reaction times are replaced with 4 h and 6 h respectively, and compared with 2 h in Example 1. The calcium-iron-aluminum composite catalytic material is applied to degrade electroplating wastewater with 20 mg / L of EDTA-Cu. The concentration of complexed copper (calculated as Cu 2+ is 20 mg / L. The addition amount of the calcium-iron-aluminum composite catalytic material is 0.5 g / L, and the addition amount of sodium hypochlorite solution with a concentration of 1 mol / L is 2 mL / L. The conditions for oxidative degradation are: temperature is room temperature, time is 1 hour, and pH is 11. The results are shown in Figure 2 .

[0063] Example 7

[0064] The calcium-iron-aluminum composite catalyst of Example 1 is used to degrade tetraaminopyridine wastewater: The experiment for ammonia nitrogen removal is carried out in a gas bath constant temperature shaker. The volume of the reaction solution is 100 mL, and the concentration of tetraaminopyridine is set at 200 mg / L and reacted at room temperature (25±5°C). The reaction process is as follows: First, add 0.5 / L of the catalytic material, then add 5 ml / L of the oxidant sodium hypochlorite solution to oxidize and remove for 90 min, take samples, and measure.

[0065] Example 8

[0066] The calcium-iron-aluminum composite catalytic material of Example 1 is used to degrade ammonia nitrogen wastewater: The experiment for ammonia nitrogen removal is carried out in a gas bath constant temperature shaker. The volume of the reaction solution is 100 mL, and the concentration of ammonia nitrogen is set at 50 mg / L and reacted at room temperature (25±5°C). The reaction process is as follows: First, add 0.5 / L of the catalytic material, then add 1 g / L of the oxidant calcium hypochlorite to oxidize and remove for 90 min, take samples, and measure.

[0067] Example 9

[0068] The calcium-iron-aluminum composite catalyst of Example 1 was used to degrade landfill leachate wastewater: The COD removal experiment was carried out in a thermostatic shaking water bath. The volume of the reaction solution was 100 mL, and the COD concentration was set at 2665 mg / L. The reaction was carried out at room temperature (25 ± 5 °C). The reaction process was as follows: First, 0.5 / L of the catalytic material was added, and then 10 mL / L of the oxidant sodium hypochlorite solution was added for 90 min of oxidation and removal. Samples were taken and measured.

[0069] Table 1 Treatment results of the prepared calcium-iron-aluminum composite catalyst for sewage.

[0070] Table 1

[0071]

[0072] Therefore, the present invention relates to the preparation of a calcium-iron-aluminum composite catalyst for degrading pollutants in electroplating wastewater with the above structure. The calcium-iron-aluminum composite catalyst has low cost, simple preparation method, low requirements for equipment, good operability, stable material structure in the hypochlorous acid oxidation system, good reuse effect, and strong adsorption capacity of the material alone for pollutants.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for oxidative degradation of organic and / or inorganic wastewater by catalyzing hypochlorite with a calcium iron aluminum composite catalyst material, characterized in that: Adding calcium iron aluminum composite catalytic material and hypochlorite into organic wastewater and / or inorganic wastewater to carry out catalytic oxidation reaction; The calcium-iron-aluminum composite catalytic material is prepared by the following method: calcium salt, iron salt and aluminum salt are dissolved in water according to a molar ratio of (3-5):1:(1-2.5), and then a strong alkaline solution is added to carry out a hydrolysis co-precipitation reaction, and the obtained precipitated product is successively centrifuged, washed, dried and ground to obtain the obtained material.

2. The method for oxidative degradation of organic and / or inorganic wastewater by using a calcium iron aluminum composite catalyst material to catalyze hypochlorite according to claim 1, characterized in that: The total mass percentage concentration of the calcium salt, iron salt and aluminum salt in water is 1-30%; The conditions of the hydrolysis coprecipitation reaction are: adding a strong alkaline solution to maintain the pH at 7-11, stirring the reaction at 5-40° C. for 0.5-3 h.

3. The method for oxidative degradation of organic and / or inorganic wastewater by using a calcium iron aluminum composite catalyst material to catalyze hypochlorite according to claim 1, characterized in that: The organic wastewater includes at least one of metal complex wastewater, printing and dyeing wastewater, antibiotic wastewater, garbage leachate, and pesticide wastewater; The inorganic wastewater includes ammonia nitrogen wastewater.

4. The method for oxidative degradation of organic and / or inorganic wastewater by using a calcium iron aluminum composite catalyst material to catalyze hypochlorite according to claim 1 or 3, characterized in that: The amount of the calcium iron aluminum composite catalyst material added to the organic wastewater and / or inorganic wastewater is regulated within the range of 0.1 to 4 g / L according to the content of pollutants to be oxidized and degraded in the organic wastewater and / or inorganic wastewater; The amount of the hypochlorite added to the organic wastewater and / or inorganic wastewater is regulated in the range of 0.1 to 20 g / L according to the content of pollutants to be oxidized and degraded in the organic wastewater and / or inorganic wastewater.

5. The method for oxidative degradation of organic and / or inorganic wastewater by using a calcium iron aluminum composite catalyst material to catalyze hypochlorite according to claim 1, 2 or 3, characterized in that: The conditions of the oxidation reaction are: temperature of 5-40° C., time of more than 1 hour, and pH of 5-11.

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