Preparation method of calcium iron cobalt composite catalyst for degrading electroplating wastewater

Abstract

The present invention discloses a preparation method of a calcium-iron-cobalt composite catalyst for degrading electroplating wastewater, comprising the following steps: dissolution treatment: dissolving calcium salt, cobalt salt, and iron salt, and then adding PVP K90 to obtain solution A; dispersion treatment: adding an alkaline solution to solution A, stirring evenly, and then adding SDBS, and ultrasonically dispersing to obtain solution B; high-temperature treatment: high-temperature reaction of solution B at 200-400°C for 20-40 minutes, and after the high-temperature reaction is completed, solid-liquid separation to obtain a precipitate; washing the precipitate and drying it to obtain the calcium-iron-cobalt composite catalyst. The calcium-iron-cobalt composite catalyst prepared by the present invention has a good degradation effect on complexed heavy metals in electroplating wastewater after being applied to electroplating wastewater treatment using hypochlorous acid oxidation technology, and calcium precipitation is greatly reduced, and the repetition efficiency and stability are greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method for preparing a calcium-iron-cobalt composite catalyst for degrading electroplating wastewater. Background Art

[0002] Electroplating industry is one of the important industrial economic fields of my country. It has brought about many environmental pollution problems while bringing huge economic benefits. Complex metals in electroplating wastewater are an industry problem. The complete removal of organic ligands and the efficient recovery of heavy metals are difficult to achieve simultaneous operation. Hypochlorous acid oxidation technology is widely used in the field of ordinary wastewater treatment, but it is not ideal for the removal of complex metals. Publication number CN 114797871A Chinese patent discloses a preparation of a calcium-iron composite catalyst for degrading pollutants in electroplating wastewater. It carries out doping of calcium element to iron material to form a calcium-iron composite catalyst, and then allows it to make hypochlorous acid oxidation technology applied to the removal of complex heavy metals in electroplating wastewater. It has a good catalytic effect in hypochlorous acid oxidation system. However, it is found in later research and development that the stability of the calcium-iron composite catalyst needs to be further improved, and the repetition efficiency is poor. Calcium precipitation is serious during application, affecting the actual use effect, and needs to be further improved. Therefore, the present invention aims to further develop a preparation method of a calcium-iron-cobalt composite catalyst for degrading electroplating wastewater, so as to better meet actual needs. Summary of the Invention

[0003] The technical problem solved by the present invention is to provide a method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater, so as to prepare a calcium iron cobalt composite catalyst that can improve the catalytic degradation of complexed heavy metals in electroplating wastewater while further improving the catalytic stability and repetition efficiency and reducing calcium precipitation.

[0004] The technical problem solved by the present invention is achieved by adopting the following technical solutions:

[0005] A method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater comprises the following steps:

[0006] Dissolution treatment: Dissolve calcium salt, cobalt salt and iron salt and add PVP K90 to obtain solution A;

[0007] Dispersion treatment: add alkaline solution to solution A, stir evenly, add SDBS, and disperse by ultrasonic to obtain solution B;

[0008] High temperature treatment: Solution B is subjected to a high temperature reaction at 200-400° C. for 20-40 minutes. After the high temperature reaction is completed, solid-liquid separation is performed to obtain a precipitate; the precipitate is washed and dried to obtain a calcium iron cobalt composite catalyst.

[0009] Furthermore, in the dissolution treatment step, the calcium salt, the cobalt salt and the iron salt are dissolved in distilled water, and the molar ratio of calcium, cobalt and iron in the solution after dissolution is 4-5:0.5-1.5:1-3.

[0010] Furthermore, the molar ratio of calcium, cobalt and iron in the solution after dissolution is 4:1:2.

[0011] Furthermore, in the dissolution treatment step, the mass ratio of the total amount of calcium salt, cobalt salt and iron salt to distilled water is 1:10~100; the first polymer ion dispersant is PVP K90, the content of PVP K90 in solution A is 0.1~0.5g / L, and PVP K90 is polyvinyl pyrrolidone.

[0012] Furthermore, the calcium salt is one or more of calcium nitrate, calcium hypochlorite, and calcium carbonate; the cobalt salt is cobalt nitrate; and the iron salt is one or more of ferric chloride, ferric sulfate, and ferric nitrate.

[0013] Furthermore, in the dispersion treatment step, after adding the alkaline solution to the solution A, magnetic stirring is adopted for 60 to 120 minutes. After the stirring is stable, the pH of the solution is 7 to 11.

[0014] Furthermore, in the dispersion treatment step, the second polymer ion dispersant is SDBS, the content of SDBS in solution B is 0.05-0.5 g / L; SDBS is sodium dodecylbenzenesulfonate.

[0015] Furthermore, in the high-temperature treatment step, solid-liquid separation is carried out in a centrifuge, and after centrifugation, the precipitate is repeatedly washed with distilled water or anhydrous alcohol solution and then centrifuged; the speed of the centrifuge is 5000-15000 r / min.

[0016] Furthermore, in the high temperature treatment step, vacuum constant temperature drying is adopted for drying, the drying temperature is 50-100° C., and the drying time is 10-30 hours.

[0017] A calcium iron cobalt composite catalyst for degrading electroplating wastewater is prepared by any of the above methods.

[0018] Beneficial effects: The preparation method of the calcium iron cobalt composite catalyst for degrading electroplating wastewater described in the present invention has a simple preparation process. After the prepared calcium iron cobalt composite catalyst is applied to electroplating wastewater treatment using hypochlorous acid oxidation technology, it has a good degradation effect on the complexed heavy metals in the electroplating wastewater, and calcium precipitation is greatly reduced, and the repetition efficiency and stability are greatly improved.

[0019] The preparation method of the calcium iron cobalt composite catalyst for degrading electroplating wastewater described in the present invention has different effects on degrading complexed heavy metals during the preparation process. When the calcium iron cobalt molar ratio is 4:1:2, the catalytic degradation effect of the calcium iron cobalt composite catalyst is the best.

[0020] The preparation method of the calcium-iron-cobalt composite catalyst for degrading electroplating wastewater of the present invention is simple, has low requirements on equipment, good operability, and a stable material structure in a hypochlorous acid oxidation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a SEM image of the calcium iron cobalt composite catalyst material in Example 1 of the present invention at 1 μm;

[0022] Figure 2 This is an infrared spectrum of the calcium iron cobalt composite catalytic material in Example 1 of the present invention;

[0023] Figure 3a 、 Figure 3b 、 Figure 3c 、 Figure 3d 、 Figure 3e They are respectively the XPS test graphs of O, Ca, Fe and Co of the calcium iron cobalt composite catalytic material in Example 1 of the present invention.

[0024] Figure 4 This is an XRD test pattern of the calcium iron cobalt composite catalyst material in Example 1 of the present invention;

[0025] Figure 5 is the pollutant removal rate of the calcium iron cobalt composite catalytic material in Example 1 of the present invention at different catalyst dosages;

[0026] Figure 6 is the pollutant removal rate of the calcium iron cobalt composite catalytic material in Example 1 of the present invention at different oxidant dosages;

[0027] Figure 7 It is the pollutant removal rate of the iron-cobalt composite catalytic material in Example 1 of the present invention at different times. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below with reference to specific embodiments.

[0029] Example 1

[0030] A method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater comprises the following steps:

[0031] Dissolution treatment: Calcium carbonate, cobalt nitrate, and ferric sulfate raw materials were mixed with distilled water and ultrasonically treated until the powders were completely dissolved. The mass ratio of the total amount of calcium salt, cobalt salt, and iron salt to distilled water was 1:50. The molar ratio of calcium, cobalt, and iron in the dissolved solution was 4:1:2. PVP K90 was then added to the fully dissolved solution to obtain Solution A. The PVP K90 content in Solution A was 3 g / L. Magnetic stirring was performed for 30 minutes.

[0032] Dispersion treatment: NaOH solution was slowly added to solution A, and the solution was stirred continuously by magnetic stirring until the pH value of the solution reached 11 for about 80 minutes. SDBS was then added and the solution was dispersed by continuous ultrasonic treatment at an ultrasonic frequency of 50 kHz to obtain solution B. The content of SDBS in solution B was 0.15 g / L.

[0033] High-temperature treatment: Solution B was placed in a high-temperature reactor and subjected to a high-temperature reaction at 300°C for 30 minutes. The resulting solution was centrifuged at 10,000 rpm to obtain a precipitate. The precipitate was washed with distilled water multiple times, and after each wash, the precipitate was centrifuged and dried in a vacuum drying oven at 80°C for 20 hours. After drying, the calcium-iron-cobalt composite catalyst was obtained.

[0034] Example 2

[0035] A method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater comprises the following steps:

[0036] Dissolution treatment: Calcium nitrate, cobalt nitrate, and ferric chloride raw materials were mixed with distilled water and ultrasonicated until the powders were completely dissolved. The mass ratio of the total amount of calcium salt, cobalt salt, and iron salt to distilled water was 1:100. The molar ratio of calcium, cobalt, and iron in the dissolved solution was 4.5:1.5:2.5. PVP K90 was then added to the fully dissolved solution to obtain Solution A. The content of PVP K90 in Solution A was 2 g / L. Magnetic stirring was performed for 30 minutes.

[0037] Dispersion treatment: NaOH solution was slowly added to solution A, and the solution was stirred continuously by magnetic stirring until the pH value of the solution reached 11 for about 80 minutes. SDBS was then added and the solution was dispersed by continuous ultrasonic treatment at an ultrasonic frequency of 50 kHz to obtain solution B. The content of SDBS in solution B was 0.1 g / L.

[0038] High-temperature treatment: Solution B was placed in a high-temperature reactor and subjected to a high-temperature reaction at 280°C for 40 minutes. The resulting solution was centrifuged at 12,000 rpm to obtain a precipitate. The precipitate was washed with distilled water multiple times, centrifuged after each wash, and dried in a vacuum drying oven at 100°C for 15 hours. After drying, a calcium-iron-cobalt composite catalyst was obtained.

[0039] Example 3

[0040] A method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater comprises the following steps:

[0041] Dissolution treatment: Calcium nitrate, cobalt nitrate, and ferric chloride raw materials were mixed with distilled water and ultrasonicated until the powders were completely dissolved. The mass ratio of the total amount of calcium salt, cobalt salt, and iron salt to distilled water was 1:60. After dissolution, the molar ratio of calcium, cobalt, and iron in the solution was 4.2:0.9:2.2. PVP K90 was then added to the fully dissolved solution to obtain Solution A. The content of PVP K90 in Solution A was 4 g / L. Magnetic stirring was performed for 30 minutes.

[0042] Dispersion treatment: NaOH solution was slowly added to solution A, and the solution was stirred continuously by magnetic stirring until the pH value of the solution reached 11 for about 80 minutes. SDBS was then added and the solution was dispersed by continuous ultrasonic treatment at an ultrasonic frequency of 50 kHz to obtain solution B. The content of SDBS in solution B was 0.2 g / L.

[0043] High-temperature treatment: Solution B was placed in a high-temperature reactor and subjected to a high-temperature reaction at 360°C for 28 minutes. The resulting solution was centrifuged at 12,000 rpm to obtain a precipitate. The precipitate was washed with distilled water multiple times, and after each wash, the precipitate was centrifuged and dried in a vacuum drying oven at 50°C for 30 hours. After drying, a calcium-iron-cobalt composite catalyst was obtained.

[0044] Comparative Example 1

[0045] Compared with Example 1, this comparative example is different in that, in the dissolution step, after the calcium salt, zirconium salt and iron salt are dissolved, PVP K90 is not added and the dispersion step is entered. The rest is the same as Example 1.

[0046] Comparative Example 2

[0047] Compared with Example 1, this comparative example is different in that APAM is not added in the dispersion treatment step, and the rest is the same as Example 1.

[0048] Comparative Example 3

[0049] Compared with Example 1, this control example is different in that, in the dissolution treatment step, the calcium salt, zirconium salt and iron salt are dissolved in distilled water, and the molar ratio of calcium, zirconium and iron in the solution after dissolution is 1:2:4. The rest is the same as Example 1.

[0050] Comparative Example 4

[0051] Compared with Example 1, this comparative example is different in that, in the high-temperature treatment step, solution B is reacted at 80° C. for 30 min. The rest is the same as Example 1.

[0052] Comparative Example 5

[0053] The calcium-iron composite catalyst is prepared by adopting the technology disclosed in Chinese patent publication number CN 114797871 A.

[0054] The calcium iron cobalt composite catalyst prepared in Example 1 was tested.

[0055] like Figure 1 As shown in FIG, the calcium iron cobalt composite catalyst prepared by the present invention has a layer block structure. Figure 2 See that 495.5cm -1 The absorption peaks near the Fe-O and Ca-O bonds are 616.5 cm -1 The absorption peak near 1377cm is caused by the stretching vibration of Co-O bond. -1 The absorption peak near 1630.6cm is caused by the stretching vibration of Fe-OH bond; -1 The absorption peak that appears near is the HOH deformation vibration peak, 3445.5cm -1 The bands are related to the stretching vibration of surface hydroxyl groups, the -OH vibration of adsorbed water and the bending vibration of Fe-OH, respectively.

[0056] In the O1s spectrum in Figure 3, the three fitted peaks at 529.1eV, 530.2eV, and 531eV can be attributed to lattice oxygen bound to the metal and adsorbed oxygen on oxygen vacancies, respectively. Abundant oxygen vacancies can enhance electron transfer capacity on the material's surface, thereby improving catalytic performance. The Fe2p spectrum reveals two pairs of spin-orbit doublets, containing Fe(II) and Fe(III). The peaks at 710.8eV and 724.5eV are attributed to the core energy levels of Fe(II), while the binding energies at 714eV and 731.6eV are attributed to the presence of Fe(III). In the Ca2p spectrum, the peaks at 345.9eV and 350eV represent Ca2p3 / 2 and Ca2p1 / 2, respectively, indicating the successful incorporation of Ca into the material. In the Co 2p spectrum, the peaks at bonding energies of 780.3, 782.5, 795.4, and 797.2 eV correspond to the Co 2p3 / 2 and Co2p1 / 2 orbitals of Co2+ and Co3+, indicating that the Co element was successfully introduced into the material.

[0057] pass Figure 4 It can be seen that the peaks at 2θ of 18.1°, 34.1°, and 50.8° correspond to Ca-OH (PDF#50-0008) and its (001), (102), and (110) crystal planes, and the peak at 2θ of 29.4° is related to Ca-O (PDF#28-0775), and the diffraction peaks at 44.2°, 51.5°, and 75.9° through (PDF#48-1719) and (PDF#51-1731) belong to Co (111) plane, Co (200) plane, and Co (220) plane, respectively. The enhancement of these peaks indicates that the crystallinity and particle size increase due to the incorporation of Ca and Co.

[0058] The calcium iron cobalt composite catalyst prepared in Example 1 was applied to the removal of complexed heavy metals in electroplating wastewater. Complexed copper (Cu 2+ The concentration of calcium iron cobalt composite catalyst was 20 mg / L. The dosage of calcium iron cobalt composite catalyst was 0.25 g / L, 0.5 g / L, 0.75 g / L and 1 g / L respectively. Figure 5 It can be seen that when the dosage of calcium iron cobalt composite catalyst is 0.5g / L, the removal rate of complex copper can reach more than 80%. When the dosage of calcium iron cobalt composite catalyst is 0.5g / L, the dosage of sodium hypochlorite oxidant is adjusted to Figure 7 It can be seen that when the dosage of sodium hypochlorite oxidant is 3 ml / L, a 90% removal effect can be achieved in 90 minutes.

[0059] Table 1 shows the sewage treatment results of the calcium iron cobalt composite catalysts prepared in Examples 1 to 3, Comparative Examples 1 to 4, and the calcium iron composite catalyst prepared in Comparative Example 5. The catalyst dosage was 0.5 g / L, the sodium hypochlorite oxidant dosage was 3 ml / L, and the reaction time was 90 min.

[0060] Table 1

[0061]

[0062]

[0063] (1) The calcium iron cobalt composite catalyst described in Example 1 and the calcium iron composite catalyst described in Comparative Example 5 were subjected to stability tests.

[0064] Take 100mL water sample of 20mg / L EDTA-Cu into a conical flask, add 0.5g / L Fe-Ca-Co and Fe-Ca composite catalyst respectively, then add 2.5g / L sodium hypochlorite and react for 90min before taking sample to measure Cu by atomic absorption. 2+ After standing, the supernatant was poured out, and 100 mL of water sample containing 20 mg / L EDTA-Cu was added again, and then 2.5 g / L sodium hypochlorite was added to react for 90 minutes. Then, the sample was sampled and the Cu was measured by atomic absorption. 2+ The results are shown in Table 2.

[0065] Table 2

[0066] First time (mg / L) Second time (mg / L) The third time (mg / L) Fourth time (mg / L) raw water 20.846 19.5725 20.066 20.5725 Fe-Ca-Co 0.377 0.8825 1.8005 2.092 Fe-Ca 0.118 0.829 2.7335 3.8015

[0067] As shown in Table 2, the calcium-iron-cobalt composite catalyst of the present invention has better repetitive stability than the calcium-iron composite catalyst.

[0068] (2) The calcium iron cobalt composite catalyst described in Example 1 and the calcium iron composite catalyst described in Comparative Example 5 were subjected to calcium precipitation detection.

[0069] Take 100mL of water sample with 20mg / L EDTA-Cu into a conical flask, add 0.5g / L of Fe-Ca-Co and Fe-Ca materials respectively, then add 2.5ml / L of sodium hypochlorite to react, and take samples for atomic absorption measurement of Ca at 0min, 15min, 30min, 45min, 60min, 75min, and 90min respectively. 2+ The results are shown in Table 3.

[0070] Table 3

[0071]

[0072] As shown in Table 3, the calcium-iron composite catalyst in the prior art has serious calcium precipitation during the reaction process, while the calcium-iron-cobalt composite catalyst of the present invention has less calcium precipitation during the reaction process and has better performance.

[0073] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater, characterized in that: The steps include: Dissolution treatment: Calcium salt, cobalt salt, and iron salt are dissolved and then a first polymer ion dispersant is added to obtain solution A; after dissolution, the molar ratio of calcium, cobalt, and iron in the solution is 4-5:0.5-1.5:1-3; the first polymer ion dispersant is PVP K90, and the content of PVP K90 in solution A is 0.1-0.5 g / L; Dispersion treatment: adding an alkaline solution to solution A, stirring uniformly, adding a second polymer ion dispersant, and ultrasonically dispersing to obtain solution B; the second polymer ion dispersant is SDBS, and the content of SDBS in solution B is 0.05-0.5 g / L; High temperature treatment: Solution B is subjected to a high temperature reaction at 200-400° C. for 20-40 minutes. After the high temperature reaction is completed, solid-liquid separation is performed to obtain a precipitate; the precipitate is washed and dried to obtain a calcium iron cobalt composite catalyst.

2. The method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater according to claim 1, wherein: In the dissolution treatment step, calcium salt, cobalt salt and iron salt are dissolved in distilled water.

3. The method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater according to claim 1, wherein: After dissolution, the molar ratio of calcium, cobalt and iron in the solution is 4:1:

2.

4. The method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater according to claim 2, wherein: In the dissolution treatment step, the mass ratio of the total amount of calcium salt, cobalt salt and iron salt to distilled water is 1:10-100.

5. The method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater according to claim 1, wherein: The calcium salt is one or more of calcium nitrate and calcium hypochlorite; the cobalt salt is cobalt nitrate; and the iron salt is one or more of ferric chloride, ferric sulfate and ferric nitrate.

6. The method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater according to claim 1, wherein: In the dispersion treatment step, after adding the alkaline solution to solution A, magnetic stirring is adopted for 60 to 120 minutes. After the stirring is stable, the pH of the solution is 7 to 11.

7. The method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater according to claim 1, wherein: In the high-temperature treatment step, solid-liquid separation is carried out in a centrifuge, and after centrifugation, the precipitate is repeatedly washed with distilled water or anhydrous alcohol solution and then centrifuged; the speed of the centrifuge is 5000~15000r / min.

8. The method for preparing a calcium iron cobalt composite catalyst for degrading electroplating wastewater according to any one of claims 1 to 7, characterized in that: In the high temperature treatment step, vacuum constant temperature drying is adopted for drying, the drying temperature is 50-100° C., and the drying time is 10-30 hours.

9. A calcium iron cobalt composite catalyst for degrading electroplating wastewater, characterized in that: The method is prepared by any one of claims 1 to 8.

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