A treatment agent for efficiently removing heavy metals from industrial wastewater and a preparation method thereof

Abstract

The invention discloses a treatment agent for efficiently removing heavy metals in industrial sewage and a preparation method thereof, and belongs to the technical field of sewage treatment. The treatment agent is compounded by modified biochar and Co-Cu doped nano titanium dioxide in proportion. The modified biochar has more active sites and specific surface area, which can better adsorb various heavy metal ions in sewage, and then the Co-Cu doped nano titanium dioxide uses photocatalysis to reduce these heavy metal ions enriched on the surface of biochar into harmless substances. The Co-Cu doped nano titanium dioxide can generate more photogenerated electrons and holes, thereby inducing a more efficient redox reaction. The two work synergistically to achieve an excellent effect of removing heavy metal ions in water, and have good market application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and specifically relates to a treatment agent for efficiently removing heavy metals from industrial sewage and a preparation method thereof. Background Art

[0002] It is well known that industrial wastewater contains a large amount of heavy metal ions, such as mercury Hg (Ⅱ), Pb (Ⅱ), Cd (Ⅱ), Cu (Ⅱ) and Cr (Ⅵ). These heavy metal ions can damage soil, water and air, threatening the ecological balance. In addition, due to the non-biodegradability of heavy metal ions, their strong permeability and accumulation will eventually reach the human body through the food chain. Once reaching a certain level, it will endanger human health. The role of removing and tracking heavy metal ions in water has always been a research hotspot in the field.

[0003] The sources of heavy metal pollutants in industrial wastewater are complex, mainly from electroplating, mining, smelting, chemical and other industries. In addition, heavy metals can accumulate in the soil for a long time, thus affecting the quality and safety of agricultural products and posing a potential health risk in the food chain. With the acceleration of industrialization, the problem of heavy metal pollution has become increasingly prominent, so effective treatment measures are urgently needed to remove heavy metal pollutants in industrial wastewater.

[0004] At present, the main methods for treating heavy metals in industrial wastewater are: 1. Electrochemical treatment, such as electroflotation, which is widely used in mine wastewater treatment. However, electrochemical treatment of wastewater requires a lot of investment and expensive electricity supply, which limits its large-scale promotion and use; 2. Chemical precipitation method, which is simple and easy to operate but requires a large amount of precipitant to reduce metal ions to an acceptable discharge concentration. They will become a new source of pollution. At the same time, the cost is high and the ability to select heavy metal ions is very poor; 3. Ion exchange method, that is, the ions of the resin are exchanged with metal ions to achieve the purpose of treating wastewater. The disadvantage is that the synthetic resin may be seriously damaged when treating wastewater contaminated by heavy metals; 4. Membrane separation method, membrane separation technology is a treatment technology that uses pressure and membrane selectivity for separation, purification and concentration, including nanofiltration membrane, reverse osmosis Permeable membrane, microfiltration membrane, ultrafiltration membrane, etc. Although the membrane separation method has a good effect on wastewater treatment, the membrane material is easily affected by environmental pollution and scaling, clogging and other phenomena, resulting in a short service life, and the membrane separation equipment usually requires a large pressure and relatively high energy consumption; 5. Adsorption method, using the physical adsorption and chemical adsorption properties of the adsorbent to remove various pollutants in wastewater, is currently a widely used and efficient sewage treatment method, but the adsorbent's own performance and the screening of the adsorbent are crucial; 6. Biological methods, such as microbial adsorption, plant repair, etc., use microorganisms or plants and other organisms to adsorb, oxidize and reduce heavy metal ions, and convert them into non-toxic or low-toxic substances. It has the advantages of being environmentally friendly and easy to operate, but the disadvantages are the specific selection of strains, high cost, and low removal efficiency. Although there are many methods for treating heavy metals in industrial wastewater, the effects vary greatly. How to choose an efficient method for removing heavy metals from industrial wastewater has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] The invention discloses a treatment agent for efficiently removing heavy metals in industrial sewage, which adopts a method combining physical and chemical technologies to efficiently remove various heavy metal ions in water.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0007] A treatment agent for efficiently removing heavy metals from industrial sewage consists of a solid agent A and a solid agent B. The solid agent A is modified biochar; the solid agent B is Co-Cu doped nano titanium dioxide.

[0008] Preferably, the mass ratio of the solid dose A to the solid dose B is 3:1.

[0009] Preferably, the modified biochar is prepared by the following method:

[0010] (1) After cleaning, clean the celery stems, cut them into small pieces of 1-5 cm, place them in a drying oven and dry them to constant weight, then transfer them to a tubular furnace and introduce nitrogen gas to calcine at high temperature for 2 h, and obtain celery stem biochar after cooling;

[0011] (2) Add 100 g of celery stem biochar and 3 g of nano zinc oxide to 1 L of deionized water and stir evenly. Soak for 15-20 min and then shake for 15-20 min. Then add 1 L of 3 mg / L NaOH solution and stir magnetically at a speed of 150-180 r / min for 12 h. After standing for 12 h-18 h, centrifuge and separate. Wash the solid product with deionized water three times, dry in an oven for 24 h, and then transfer to a muffle furnace for high-temperature calcination for 2 h to obtain zinc-modified biochar.

[0012] (3) Take 5 g of FeCl3 and dissolve it in 1 L of deionized water. Then take 20 g of the zinc-modified biochar obtained in step (2) and add it to the solution. Stir it magnetically for 4-5 h, add NaOH to adjust the pH to 11, stir it for 2 h, let it stand for 24 h, and centrifuge it in a centrifuge. Wash the solid product with deionized water until it is neutral, dry it in an oven, and grind it into powder to obtain the modified biochar.

[0013] Furthermore, the specific method of high temperature calcination in step (1) is to increase the temperature to 500° C. at a rate of 8° C. / min and calcine for 2 hours.

[0014] Furthermore, the specific method of high temperature calcination in step (2) is to increase the temperature to 400° C. at a rate of 5° C. / min and calcine for 2 hours.

[0015] Preferably, the Co-Cu doped nano titanium dioxide is prepared by the following method:

[0016] a. Slowly drop tetrabutyl titanate into 4 times the amount of anhydrous ethanol and mix. After the addition is complete, stir for 30 minutes to obtain solution A;

[0017] b. Mix glacial acetic acid, anhydrous ethanol and deionized water in proportion, stir evenly, and adjust the pH to 2-3 with a small amount of hydrochloric acid to obtain solution B;

[0018] c. Add Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzene sulfonate to solution B and stir until completely dissolved to obtain solution C;

[0019] d. Solution A was dripped into solution C at a rate of 10 ml / min. After dripping, magnetic stirring was continued for 30 min to obtain a gel. The volume ratio of solution A to solution C was 1:1.

[0020] e. The gel was placed in an oven and dried at 100°C for 6 h, and then transferred to a muffle furnace and calcined at 400°C for 2 h to obtain Co-Cu doped nano-titanium dioxide.

[0021] Preferably, in step b, the volume ratio of glacial acetic acid, anhydrous ethanol and deionized water is 1:8-10:2-3.

[0022] Preferably, in step c, the dosage ratio of solution B, Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzenesulfonate is 100-120 ml: 5 mmol: 10 mmol: 0.5-1 g.

[0023] Preferably, solid agent A is first added to industrial sewage and stirred evenly, then placed in a constant temperature oscillator at 35-40°C and oscillated at a speed of 180-200 r / min for 12 hours, and then solid agent B is added. After stirring evenly, a 200W xenon lamp is used for irradiation for 2 hours, and then the solid and liquid are separated.

[0024] The present invention provides a method for preparing the above-mentioned treatment agent for efficiently removing heavy metals from industrial wastewater, comprising the following steps:

[0025] (1) Preparing solid dosage form A;

[0026] (2) Preparing solid dosage form B;

[0027] (3) The solid dosage form A and the solid dosage form B are packaged separately and then divided into subpackages to obtain the final product.

[0028] The dosage of the treatment agent for efficiently removing heavy metals from industrial sewage of the present invention is: 4 g of the treatment agent of the present invention is used per 1 L of sewage.

[0029] Biochar has a large specific surface area and rich pore structure, which can adsorb heavy metal ions in wastewater through physical adsorption. At the same time, the surface of biochar also contains a variety of functional groups, such as carboxyl, hydroxyl, phenolic hydroxyl, etc. These functional groups can react with heavy metal ions to form stable complexes, thereby fixing heavy metal ions. Therefore, biochar is an environmentally friendly and relatively low-cost material and is widely used in wastewater treatment. However, ordinary biochar has limited effect on the removal of heavy metal ions in sewage. In practical applications, the performance of biochar can be optimized by changing its preparation conditions (such as raw materials, pyrolysis temperature, etc.) to improve its removal efficiency of heavy metal ions. The present invention uses celery stems as raw materials to prepare biochar, and uses zinc oxide nanoparticles and ferric chloride to modify biochar. The specific surface area and pore volume of biochar are significantly increased, the active sites are significantly increased, and the adsorption capacity of heavy metals is significantly enhanced. At the same time, nano zinc oxide can produce hydroxyl groups during the adsorption process, and these hydroxyl groups can form complexes with heavy metal ions, thereby further promoting the removal of heavy metals; and the iron-modified biochar usually has good stability and can maintain its adsorption performance under different environmental conditions, which helps to ensure the continuous and effective removal of heavy metals during the treatment process. The two jointly modify the biochar to greatly improve the ability of biochar to adsorb and remove heavy metals in sewage.

[0030] The present invention also uses Co-Cu doped nano titanium dioxide as a heavy metal treatment agent. Usually, ordinary titanium dioxide catalytically treats heavy metal ions in sewage by absorbing light energy and generating electrons with strong reducing properties under light conditions, which can undergo reduction reactions with heavy metal ions in wastewater and convert them into their corresponding hydroxides or oxides. The nano titanium dioxide doped with Co-Cu can significantly improve the photocatalytic performance of nano titanium dioxide. The doped catalyst has higher photocatalytic activity, can more effectively utilize light energy to generate electron-hole pairs, and promote the generation of active free radicals. Co-Cu doping can also optimize the energy band structure of nano titanium dioxide, making it easier to absorb visible light, thereby broadening the spectral response range of the photocatalyst. Compared with ordinary titanium dioxide catalysts, the doped catalyst has a higher removal rate for heavy metals, a faster reaction rate, and the doped nano titanium dioxide photocatalyst has a stronger adaptability to sewage environments.

[0031] The beneficial effect of the present invention is that the present invention adopts modified biochar and modified nano-titanium dioxide in a suitable ratio as heavy metal treatment agents in sewage, and the two act synergistically, and the heavy metal ions adsorbed on the surface of the biochar can then be catalytically degraded by the Co-Cu doped nano-titanium dioxide under light conditions and converted into harmless substances. This combination of adsorption enrichment and degradation conversion effectively improves the removal efficiency of heavy metal ions. At the same time, the photocatalytic degradation process can remove the heavy metal ions adsorbed on the surface of the biochar, thereby restoring the adsorption capacity of the biochar. The biochar can be reused, which prolongs its service life and reduces the processing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The SEM images of the modified biochar used in the present invention before and after modification, wherein a is before modification and b is after modification;

[0033] Figure 2 The SEM images of the nano-titanium dioxide used in the present invention before and after doping with Co-Cu, where a is before doping modification and b is after doping modification;

[0034] Figure 3 The solid agent A and the solid agent B in different proportions in the treatment agent of the present invention are used to treat Cr in sewage. 3+ , Pb 2+ , Cu 2+ 、Zn 2+ Effect of removal rate of four heavy metal ions;

[0035] Figure 4 This is a diagram showing the effect of heavy metal treatment agents in different treatment groups being applied to wastewater treatment in the same chemical plant. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below in conjunction with specific embodiments, but is not limited thereto. The nano zinc oxide used in the present invention is purchased from Jiangsu Tianxing New Materials Co., Ltd., model: TZP-50, particle size 30 nm.

[0037] Example 1

[0038] A treatment agent for efficiently removing heavy metals from industrial sewage, which is composed of a solid agent A and a solid agent B, wherein the solid agent A is modified biochar; and the solid agent B is Co-Cu doped nano titanium dioxide. The mass ratio of the solid agent A to the solid agent B is 3:1.

[0039] The modified biochar is prepared by the following method:

[0040] (1) After cleaning, clean the celery stems, cut them into small segments of 1-5 cm, place them in a drying oven and dry them to constant weight, then transfer them to a tubular furnace, introduce nitrogen gas, and heat them to 500 °C at a rate of 8 °C / min, calcine them for 2 h, and obtain celery stem biochar after cooling;

[0041] (2) Add 100 g of celery stem biochar and 3 g of nano zinc oxide to 1 L of deionized water and stir evenly. Soak for 15 min and then shake for 15 min. Then add 1 L of 3 mg / L NaOH solution and stir magnetically at a speed of 150 r / min for 12 h. After standing for 12 h, centrifuge and separate. The solid product is washed 3 times with deionized water, dried in an oven for 24 h, and then transferred to a muffle furnace and heated to 400 °C at a rate of 5 °C / min. Calcined for 2 h to obtain zinc-modified biochar.

[0042] (3) Take 5 g of FeCl3 and dissolve it in 1 L of deionized water. Then take 20 g of the zinc-modified biochar obtained in step (2) and add it to the solution. Stir it magnetically for 4 h, add NaOH to adjust the pH to 11, stir it for 2 h, let it stand for 24 h, and centrifuge it in a centrifuge. Wash the solid product with deionized water until it is neutral, dry it in an oven, and grind it into powder to obtain the modified biochar.

[0043] The Co-Cu doped nano titanium dioxide is prepared by the following method:

[0044] a. Slowly drop tetrabutyl titanate into 4 times the amount of anhydrous ethanol and mix. After the addition is complete, stir for 30 minutes to obtain solution A;

[0045] b. Mix glacial acetic acid, anhydrous ethanol and deionized water in proportion, stir evenly, and adjust the pH to 2 with a small amount of hydrochloric acid to obtain solution B; the volume ratio of glacial acetic acid, anhydrous ethanol and deionized water is 1:8:2;

[0046] c. Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzene sulfonate were added to solution B and stirred until completely dissolved to obtain solution C; the amount ratio of solution B, Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzene sulfonate was 100ml:5mmol:10mmol:0.5g;

[0047] d. Solution A was dripped into solution C at a rate of 10 ml / min. After dripping, magnetic stirring was continued for 30 min to obtain a gel. The volume ratio of solution A to solution C was 1:1.

[0048] e. The gel was placed in an oven and dried at 100°C for 6 h, and then transferred to a muffle furnace and calcined at 400°C for 2 h to obtain Co-Cu doped nano-titanium dioxide.

[0049] When the treatment agent of the present invention is used, solid agent A is first added to industrial sewage and stirred evenly, then placed in a constant temperature oscillator at 35°C and oscillated at a speed of 150r / min for 12h, and then solid agent B is added. After stirring evenly, a 200W xenon lamp is used for irradiation treatment for 2h, and then the solid and liquid are separated.

[0050] The method for preparing the above-mentioned treatment agent for efficiently removing heavy metals from industrial wastewater comprises the following steps:

[0051] (1) Preparing solid dosage form A;

[0052] (2) Preparing solid dosage form B;

[0053] (3) The solid dosage form A and the solid dosage form B are packaged separately and then divided into subpackages to obtain the final product.

[0054] Example 2

[0055] A treatment agent for efficiently removing heavy metals from industrial sewage, which is composed of a solid agent A and a solid agent B, wherein the solid agent A is modified biochar; and the solid agent B is Co-Cu doped nano titanium dioxide. The mass ratio of the solid agent A to the solid agent B is 3:1.

[0056] The modified biochar is prepared by the following method:

[0057] (1) After cleaning, clean the celery stems, cut them into small segments of 1-5 cm, place them in a drying oven and dry them to constant weight, then transfer them to a tubular furnace, introduce nitrogen gas, and heat them to 500 °C at a rate of 8 °C / min, calcine them for 2 h, and obtain celery stem biochar after cooling;

[0058] (2) Add 100 g of celery stem biochar and 3 g of nano zinc oxide to 1 L of deionized water and stir evenly. Soak for 20 min and then shake for 20 min. Then add 1 L of 3 mg / L NaOH solution and stir magnetically at a speed of 180 r / min for 12 h. After standing for 18 h, centrifuge and separate. The solid product is washed 3 times with deionized water, dried in an oven for 24 h, and then transferred to a muffle furnace and heated to 400 °C at a rate of 5 °C / min. Calcined for 2 h to obtain zinc-modified biochar.

[0059] (3) Take 5 g of FeCl3 and dissolve it in 1 L of deionized water. Then take 20 g of the zinc-modified biochar obtained in step (2) and add it to the solution. Stir it magnetically for 5 h, add NaOH to adjust the pH to 11, stir it for 2 h, let it stand for 24 h, and centrifuge it in a centrifuge. Wash the solid product with deionized water until it is neutral, dry it in an oven, and grind it into powder to obtain the modified biochar.

[0060] The Co-Cu doped nano titanium dioxide is prepared by the following method:

[0061] a. Slowly drop tetrabutyl titanate into 4 times the amount of anhydrous ethanol and mix. After the addition is complete, stir for 30 minutes to obtain solution A;

[0062] b. Mix glacial acetic acid, anhydrous ethanol and deionized water in proportion, stir evenly, and adjust the pH to 3 with a small amount of hydrochloric acid to obtain solution B; the volume ratio of glacial acetic acid, anhydrous ethanol and deionized water is 1:10:3;

[0063] c. Add Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzene sulfonate to solution B and stir until completely dissolved to obtain solution C; the amount ratio of solution B, Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzene sulfonate is 120ml:5mmol:10mmol:1g;

[0064] d. Solution A was dripped into solution C at a rate of 10 ml / min. After dripping, magnetic stirring was continued for 30 min to obtain a gel. The volume ratio of solution A to solution C was 1:1.

[0065] e. The gel was placed in an oven and dried at 100°C for 6 h, and then transferred to a muffle furnace and calcined at 400°C for 2 h to obtain Co-Cu doped nano-titanium dioxide.

[0066] When the treatment agent of the present invention is used, solid agent A is first added to industrial sewage and stirred evenly, then placed in a constant temperature oscillator at 40°C and oscillated at a speed of 180r / min for 12h, and then solid agent B is added. After stirring evenly, a 200W xenon lamp is used for irradiation treatment for 2h, and then the solid and liquid are separated.

[0067] The method for preparing the above-mentioned treatment agent for efficiently removing heavy metals from industrial wastewater comprises the following steps:

[0068] (1) Preparing solid dosage form A;

[0069] (2) Preparing solid dosage form B;

[0070] (3) The solid dosage form A and the solid dosage form B are packaged separately and then divided into subpackages to obtain the final product.

[0071] Example 3

[0072] A treatment agent for efficiently removing heavy metals from industrial sewage, which is composed of a solid agent A and a solid agent B, wherein the solid agent A is modified biochar; and the solid agent B is Co-Cu doped nano titanium dioxide. The mass ratio of the solid agent A to the solid agent B is 3:1.

[0073] The modified biochar is prepared by the following method:

[0074] (1) After cleaning, clean the celery stems, cut them into small pieces of 1-5 cm, place them in a drying oven and dry them to constant weight, then transfer them to a tubular furnace, introduce nitrogen gas, and heat them to 500 °C at a rate of 8 °C / min, calcine them for 2 h, and obtain celery stem biochar after cooling;

[0075] (2) Add 100 g of celery stem biochar and 3 g of nano zinc oxide to 1 L of deionized water and stir evenly. Soak for 15 min and then shake for 15 min. Then add 1 L of 3 mg / L NaOH solution and stir magnetically at a speed of 180 r / min for 12 h. After standing for 16 h, centrifuge and separate. The solid product is washed 3 times with deionized water, dried in an oven for 24 h, and then transferred to a muffle furnace and heated to 400 °C at a rate of 5 °C / min. Calcined for 2 h to obtain zinc-modified biochar.

[0076] (3) Take 5 g of FeCl3 and dissolve it in 1 L of deionized water. Then take 20 g of the zinc-modified biochar obtained in step (2) and add it to the solution. Stir it magnetically for 5 h, add NaOH to adjust the pH to 11, stir it for 2 h, let it stand for 24 h, and centrifuge it in a centrifuge. Wash the solid product with deionized water until it is neutral, dry it in an oven, and grind it into powder to obtain the modified biochar.

[0077] The Co-Cu doped nano titanium dioxide is prepared by the following method:

[0078] a. Slowly drop tetrabutyl titanate into 4 times the amount of anhydrous ethanol and mix. After the addition is complete, stir for 30 minutes to obtain solution A;

[0079] b. Mix glacial acetic acid, anhydrous ethanol and deionized water in proportion, stir evenly, and adjust the pH to 2-3 with a small amount of hydrochloric acid to obtain solution B; the volume ratio of glacial acetic acid, anhydrous ethanol and deionized water is 1:9:2;

[0080] c. Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzenesulfonate were added to solution B and stirred until completely dissolved to obtain solution C; the amount ratio of solution B, Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzenesulfonate was 100ml:5mmol:10mmol:0.8g;

[0081] d. Solution A was dripped into solution C at a rate of 10 ml / min. After dripping, magnetic stirring was continued for 30 min to obtain a gel. The volume ratio of solution A to solution C was 1:1.

[0082] e. The gel was placed in an oven and dried at 100°C for 6 h, and then transferred to a muffle furnace and calcined at 400°C for 2 h to obtain Co-Cu doped nano-titanium dioxide.

[0083] When the treatment agent of the present invention is used, solid agent A is first added to industrial sewage and stirred evenly, then placed in a constant temperature oscillator at 38°C and oscillated at a speed of 160r / min for 12h, and then solid agent B is added. After stirring evenly, a 200W xenon lamp is used for irradiation treatment for 2h, and then the solid and liquid are separated.

[0084] The method for preparing the above-mentioned treatment agent for efficiently removing heavy metals from industrial wastewater comprises the following steps:

[0085] (1) Preparing solid dosage form A;

[0086] (2) Preparing solid dosage form B;

[0087] (3) The solid dosage form A and the solid dosage form B are packaged separately and then divided into subpackages to obtain the final product.

[0088] Comparative Example 1

[0089] A treatment agent for efficiently removing heavy metals from industrial wastewater, which is composed of a solid agent A and a solid agent B, wherein the solid agent A is biochar; the solid agent B is nano titanium dioxide; the mass ratio of the solid agent A to the solid agent B is 3:1. The nano titanium dioxide is purchased from Jiangsu Tianxing New Materials Co., Ltd., model TTP-A12.

[0090] The preparation method of biochar is as follows: take celery stems, clean them, cut them into small segments of 1-5 cm, place them in a drying oven to dry to constant weight, then transfer them to a tubular furnace, introduce nitrogen gas, raise the temperature to 500°C at a rate of 8°C / min, calcine for 2 hours, and obtain biochar after cooling.

[0091] When the treatment agent of this comparative example is used, solid agent A is first added to industrial sewage and stirred evenly, then placed in a constant temperature oscillator at 38°C and 160r / min for 12h, and then solid agent B is added. After stirring evenly, a 200W xenon lamp is used for irradiation treatment for 2h, and then the solid and liquid are separated.

[0092] Comparative Example 2

[0093] A treatment agent for efficiently removing heavy metals from industrial wastewater, which is composed of a solid agent A and a solid agent B, wherein the solid agent A is modified biochar; and the solid agent B is nano titanium dioxide. The mass ratio of the solid agent A to the solid agent B is 3:1. The nano titanium dioxide is purchased from Jiangsu Tianxing New Materials Co., Ltd., model TTP-A12.

[0094] The modified biochar is prepared by the following method:

[0095] (1) After cleaning, clean the celery stems, cut them into small pieces of 1-5 cm, place them in a drying oven and dry them to constant weight, then transfer them to a tubular furnace, introduce nitrogen gas, and heat them to 500 °C at a rate of 8 °C / min, calcine them for 2 h, and obtain celery stem biochar after cooling;

[0096] (2) Add 100 g of celery stem biochar and 3 g of nano zinc oxide to 1 L of deionized water and stir evenly. Soak for 15 min and then shake for 15 min. Then add 1 L of 3 mg / L NaOH solution and stir magnetically at a speed of 180 r / min for 12 h. After standing for 16 h, centrifuge and separate. The solid product is washed 3 times with deionized water, dried in an oven for 24 h, and then transferred to a muffle furnace and heated to 400 °C at a rate of 5 °C / min. Calcined for 2 h to obtain zinc-modified biochar.

[0097] (3) Take 5 g of FeCl3 and dissolve it in 1 L of deionized water. Then take 20 g of the zinc-modified biochar obtained in step (2) and add it to the solution. Stir it magnetically for 5 h, add NaOH to adjust the pH to 11, stir it for 2 h, let it stand for 24 h, and centrifuge it in a centrifuge. Wash the solid product with deionized water until it is neutral, dry it in an oven, and grind it into powder to obtain the modified biochar.

[0098] When the treatment agent of this comparative example is used, solid agent A is first added to industrial sewage and stirred evenly, then placed in a constant temperature oscillator at 38°C and 160r / min for 12h, and then solid agent B is added. After stirring evenly, a 200W xenon lamp is used for irradiation treatment for 2h, and then the solid and liquid are separated.

[0099] The method for preparing the above-mentioned treatment agent for efficiently removing heavy metals from industrial wastewater comprises the following steps:

[0100] (1) Preparing solid dosage form A;

[0101] (2) The solid dosage form A and the solid dosage form B (nano titanium dioxide) are packaged separately and then divided into subpackages to obtain the final product.

[0102] Comparative Example 3

[0103] A treatment agent for efficiently removing heavy metals from industrial sewage, which is composed of a solid agent A and a solid agent B, wherein the solid agent A is biochar; and the solid agent B is Co-Cu doped nano titanium dioxide. The mass ratio of the solid agent A to the solid agent B is 3:1.

[0104] The biochar is prepared by the following method: clean the celery stems, cut them into small segments of 1-5 cm, place them in a drying oven and dry them to constant weight, then transfer them to a tubular furnace, introduce nitrogen gas, raise the temperature to 500° C. at a rate of 8° C. / min, calcine for 2 hours, and obtain biochar after cooling.

[0105] The Co-Cu doped nano titanium dioxide is prepared by the following method:

[0106] a. Slowly drop tetrabutyl titanate into 4 times the amount of anhydrous ethanol and mix. After the addition is complete, stir for 30 minutes to obtain solution A;

[0107] b. Mix glacial acetic acid, anhydrous ethanol and deionized water in proportion, stir evenly, and adjust the pH to 2-3 with a small amount of hydrochloric acid to obtain solution B; the volume ratio of glacial acetic acid, anhydrous ethanol and deionized water is 1:9:2;

[0108] c. Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzenesulfonate were added to solution B and stirred until completely dissolved to obtain solution C; the amount ratio of solution B, Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzenesulfonate was 100ml:5mmol:10mmol:0.8g;

[0109] d. Solution A was dripped into solution C at a rate of 10 ml / min. After dripping, magnetic stirring was continued for 30 min to obtain a gel. The volume ratio of solution A to solution C was 1:1.

[0110] e. The gel was placed in an oven and dried at 100°C for 6 h, and then transferred to a muffle furnace and calcined at 400°C for 2 h to obtain Co-Cu doped nano-titanium dioxide.

[0111] When the treatment agent of the present invention is used, solid agent A is first added to industrial sewage and stirred evenly, then placed in a constant temperature oscillator at 38°C and oscillated at a speed of 160r / min for 12h, and then solid agent B is added. After stirring evenly, a 200W xenon lamp is used for irradiation treatment for 2h, and then the solid and liquid are separated.

[0112] The method for preparing the above-mentioned treatment agent for efficiently removing heavy metals from industrial wastewater comprises the following steps:

[0113] (1) Preparing solid dosage form A;

[0114] (2) Preparing solid dosage form B;

[0115] (3) The solid dosage form A and the solid dosage form B are packaged separately and then divided into subpackages to obtain the final product.

[0116] Comparative Example 4

[0117] The invention discloses a treatment agent for efficiently removing heavy metals from industrial wastewater, which is made of modified biochar.

[0118] The modified biochar is prepared by the following method:

[0119] (1) After cleaning, clean the celery stems, cut them into small pieces of 1-5 cm, place them in a drying oven and dry them to constant weight, then transfer them to a tubular furnace, introduce nitrogen gas, and heat them to 500 °C at a rate of 8 °C / min, calcine them for 2 h, and obtain celery stem biochar after cooling;

[0120] (2) Add 100 g of celery stem biochar and 3 g of nano zinc oxide to 1 L of deionized water and stir evenly. Soak for 15 min and then shake for 15 min. Then add 1 L of 3 mg / L NaOH solution and stir magnetically at a speed of 180 r / min for 12 h. After standing for 16 h, centrifuge and separate. The solid product is washed 3 times with deionized water, dried in an oven for 24 h, and then transferred to a muffle furnace and heated to 400 °C at a rate of 5 °C / min. Calcined for 2 h to obtain zinc-modified biochar.

[0121] (3) Take 5 g of FeCl3 and dissolve it in 1 L of deionized water. Then take 20 g of the zinc-modified biochar obtained in step (2) and add it to the solution. Stir it magnetically for 5 h, add NaOH to adjust the pH to 11, stir it for 2 h, let it stand for 24 h, and centrifuge it in a centrifuge. Wash the solid product with deionized water until it is neutral, dry it in an oven, and grind it into powder to obtain the modified biochar.

[0122] When the treatment agent of this comparative example is used, the treatment agent is added to the industrial sewage and stirred evenly, then placed in a constant temperature oscillator at 38°C and 160r / min for 12h, then irradiated with a 200W xenon lamp for 2h, and then the solid-liquid separation is performed.

[0123] Comparative Example 5

[0124] The invention discloses a treatment agent for efficiently removing heavy metals from industrial sewage, which is made of Co-Cu doped nano titanium dioxide.

[0125] The Co-Cu doped nano titanium dioxide is prepared by the following method:

[0126] a. Slowly drop tetrabutyl titanate into 4 times the amount of anhydrous ethanol and mix. After the addition is complete, stir for 30 minutes to obtain solution A;

[0127] b. Mix glacial acetic acid, anhydrous ethanol and deionized water in proportion, stir evenly, and adjust the pH to 2-3 with a small amount of hydrochloric acid to obtain solution B; the volume ratio of glacial acetic acid, anhydrous ethanol and deionized water is 1:9:2;

[0128] c. Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzenesulfonate were added to solution B and stirred until completely dissolved to obtain solution C; the amount ratio of solution B, Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzenesulfonate was 100ml:5mmol:10mmol:0.8g;

[0129] d. Solution A was dripped into solution C at a rate of 10 ml / min. After dripping, magnetic stirring was continued for 30 min to obtain a gel. The volume ratio of solution A to solution C was 1:1.

[0130] e. The gel was placed in an oven and dried at 100°C for 6 h, and then transferred to a muffle furnace and calcined at 400°C for 2 h to obtain Co-Cu doped nano-titanium dioxide.

[0131] When the treatment agent of this comparative example is used, the treatment agent is added to the industrial sewage and stirred evenly, then placed in a constant temperature oscillator at 38°C and 160r / min for 12h, then irradiated with a 200W xenon lamp for 2h, and then the solid-liquid separation is performed.

[0132] Test Example 1

[0133] The specific surface area and surface morphology of the celery stem biochar and modified biochar prepared by the present invention were tested and analyzed. Figure 1 and Table 1.

[0134] Table 1 BET characterization results of celery stem biochar before and after modification

[0135]

[0136] from Figure 1 It can be seen that there are many particles dispersed on the surface and pores of the modified biochar, and the surface is rough and uneven. This should be due to the dispersion of nano zinc oxide and ferric chloride particles on the surface of the biochar. After the modification treatment of the present invention, the specific surface area, pore volume and pore size of the biochar are increased, thereby improving its ability to adsorb heavy metal ions in sewage.

[0137] At the same time, the surface morphology of the nano-titanium dioxide used in the present invention before and after doping with Co-Cu (gel solution B in the preparation process of Co-Cu doped nano-titanium dioxide) was tested, and its SEM image is shown in Figure 2 .Depend on Figure 2 It can be seen that the shape of pure nano-TiO2 is similar to that of a sphere and its distribution is relatively concentrated. After the sample is doped with ions, the structure of nano-TiO2 is still similar to that of a sphere, indicating that the crystal shape of nano-TiO2 has not changed due to ion doping.

[0138] Test Example 2

[0139] Accurately weigh 7.6958 g Cr(NO3)3·9H2O, 1.5986 g Pb(NO3)2, 3.8013 g Cu(NO3)2·3H2O, and 4.5482 g Zn(NO3)2·6H2O, and add them to a 500 mL beaker. Add nitric acid to dissolve them, then transfer the solution to a 1000 mL volumetric flask and dilute to volume with deionized water to prepare a Cr(NO3)3·9H2O solution with a concentration of 1000 µg / mL. 3+ , Pb 2+ , Cu 2+ 、Zn 2+ Simulated sewage stock solution. Take the above simulated sewage stock solution and prepare 50 µg / mL, 100 µg / mL, and 200 µg / mL of Cr 3+ , Pb 2+ , Cu 2+ 、Zn 2+ Simulated sewage 1, simulated sewage 2, and simulated sewage 3. Then, the treatment agents for efficiently removing heavy metals from industrial sewage prepared in Examples 1-3 of the present invention and Comparative Examples 1-6 were used to treat the wastewater, and the effects of different treatment groups on Cr at different concentrations were measured. 3+ , Pb 2+ , Cu 2+ 、Zn 2+ The removal rate is shown in Table 2-Table 4. Removal rate = (concentration before adding treatment agent - concentration after adding treatment agent) / concentration before adding treatment agent * 100%.

[0140] Table 2 Removal rates of different heavy metal ions in simulated sewage 1 after treatment with different treatment agents

[0141]

[0142] Table 3 Removal rates of different heavy metal ions after simulated sewage 2 was treated with different treatment agents

[0143]

[0144] Table 4 Removal rates of different heavy metal ions after simulated sewage 3 was treated with different treatment agents

[0145]

[0146] From the results in Tables 2-4 above, it can be seen that for wastewater contaminated with heavy metal ions of different concentrations, the use of the industrial wastewater treatment agent of the present invention has a significant effect on the Cr 3+ , Pb 2+ , Cu 2+ 、Zn 2+The removal rates are all high, which are significantly better than the removal effects of Comparative Examples 1-5. From the data of Comparative Examples 4 and 5, it can be seen that the combined use of the modified biochar of the present invention and Co-Cu doped nano-titanium dioxide has an obvious synergistic effect on the removal of heavy metal ions in sewage. The removal effects of unmodified biochar or nano-titanium dioxide alone for heavy metals in industrial wastewater are relatively poor.

[0147] Test Example 3

[0148] Taking the treatment agent for efficient removal of heavy metals in industrial wastewater prepared in Example 3 as an example, the effects of different proportions of solid agent A and solid agent B on Cr in wastewater were studied. 3+ , Pb 2+ , Cu 2+ 、Zn 2+ The removal rate of four heavy metal ions, where M1 is solid agent A: solid agent B = 1:1, M2 is solid agent A: solid agent B = 2:1, M3 is solid agent A: solid agent B = 3:1, M4 is solid agent A: solid agent B = 4:1, M5 is solid agent A: solid agent B = 5:1, the concentration of the four heavy metal ions in the simulated sewage in the test room is 100µg / mL, the concentration of the four metal ions is measured again after treatment, and the removal rate is calculated. The results are shown in Figure 3 .from Figure 3 It can be seen from the results that the dosage ratio of solid agent A and solid agent B in the sewage treatment agent of the present invention has a more obvious effect on the removal of heavy metals, and the M3 treatment group has the best effect. Therefore, the present invention selects the optimal ratio to prepare the heavy metal treatment agent in industrial sewage.

[0149] Application Examples

[0150] Wastewater from a chemical plant in Linshu County, Linyi City was selected as a test sample. The wastewater treatment agents prepared in Example 3 and Comparative Examples 1-5 were used to treat the wastewater according to the corresponding usage. The Cr content in the wastewater was determined before using the wastewater treatment agents. 3+ , Pb 2+ , Cu 2+ 、Zn 2+ The concentrations of the four heavy metal ions were measured again after treatment, and the removal rates were calculated. The results are shown in Table 5 below.

[0151] Table 5 Chemical plant wastewater treatment results

[0152]

[0153] It can be seen from Table 5 that the treatment agent for removing heavy metals from sewage of the present invention has excellent removal effect on heavy metal ions in chemical plant sewage, and the water quality is significantly improved after treatment. Figure 4The effects of comparative examples 1 to 5 are relatively poor. It can be seen that the heavy metal treatment agent of the present invention has a good application effect.

[0154] It should be noted that the above embodiments are only partial embodiments of the preferred methods of implementing the present invention, rather than all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A treatment agent for removing heavy metals from industrial wastewater, characterized in that: It is composed of a solid agent A and a solid agent B, wherein the solid agent A is modified biochar; the solid agent B is Co-Cu doped nano titanium dioxide; the mass ratio of the solid agent A to the solid agent B is 3:1; The modified biochar is prepared by the following method: (1) After cleaning, clean the celery stems, cut them into small pieces of 1-5 cm, place them in a drying oven and dry them to constant weight, then transfer them to a tubular furnace and introduce nitrogen gas to calcine at high temperature for 2 h, and obtain celery stem biochar after cooling; (2) Add 100 g of celery stem biochar and 3 g of nano zinc oxide to 1 L of deionized water and stir evenly. Soak for 15-20 min and then shake for 15-20 min. Then add 1 L of 3 mg / L NaOH solution and stir magnetically at a speed of 150-180 r / min for 12 h. After standing for 12 h-18 h, centrifuge and separate. Wash the solid product with deionized water three times, dry in an oven for 24 h, and then transfer to a muffle furnace for high-temperature calcination for 2 h to obtain zinc-modified biochar. (3) Take 5g of FeCl3 and dissolve it in 1L of deionized water, then take 20g of the zinc-modified biochar obtained in step (2) and add it to the solution, stir it under magnetic force for 4-5h, add NaOH to adjust the pH to 11, stir it for 2h, let it stand for 24h, centrifuge it in a centrifuge, wash the solid product with deionized water until it is neutral, dry it in an oven and grind it into powder to obtain modified biochar; The Co-Cu doped nano titanium dioxide is prepared by the following method: a. Slowly drop tetrabutyl titanate into 4 times the amount of anhydrous ethanol and mix. After the addition is complete, stir for 30 minutes to obtain solution A; b. Mix glacial acetic acid, anhydrous ethanol and deionized water in proportion, stir evenly, and adjust the pH to 2-3 with a small amount of hydrochloric acid to obtain solution B; c. Add Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzene sulfonate to solution B and stir until completely dissolved to obtain solution C; d. Solution A was dripped into solution C at a rate of 10 ml / min. After dripping, magnetic stirring was continued for 30 min to obtain a gel. The volume ratio of solution A to solution C was 1:

1. e. The gel was placed in an oven and dried at 100°C for 6 h, and then transferred to a muffle furnace and calcined at 400°C for 2 h to obtain Co-Cu doped nano-titanium dioxide.

2. The treatment agent for removing heavy metals from industrial wastewater according to claim 1, characterized in that: The specific method of high temperature calcination in step (1) is to increase the temperature to 500° C. at a rate of 8° C. / min and calcine for 2 hours.

3. The treatment agent for removing heavy metals from industrial wastewater according to claim 1, characterized in that: The specific method of high temperature calcination in step (2) is to increase the temperature to 400° C. at a rate of 5° C. / min and calcine for 2 hours.

4. The treatment agent for removing heavy metals from industrial wastewater according to claim 1, characterized in that: In the step b, the volume ratio of glacial acetic acid, anhydrous ethanol and deionized water is 1:8-10:2-3.

5. The treatment agent for removing heavy metals from industrial wastewater according to claim 1, characterized in that: In the step c, the dosage ratio of solution B, Co(NO3)2·6H2O, CuCl2 and sodium dodecylbenzenesulfonate is 100-120ml:5mmol:10mmol:0.5-1g.

6. The treatment agent for removing heavy metals from industrial wastewater according to claim 1, characterized in that: First add solid agent A to the industrial sewage and stir evenly, then place it in a constant temperature oscillator at 35-40℃ and 180-200r / min for 12h, then add solid agent B, stir evenly, irradiate with a 200W xenon lamp for 2h, and then separate the solid and liquid.

7. A method for preparing a treatment agent for removing heavy metals from industrial wastewater according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Preparing solid dosage form A; (2) Preparing solid dosage form B; (3) The solid dosage form A and the solid dosage form B are packaged separately and then divided into subpackages to obtain the final product.

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