Composite solid decolorizing powder and its preparation method

Abstract

The application discloses a composite solid decoloring powder and a preparation method thereof, and belongs to the technical field of water treatment agent preparation. The modified nano titanium dioxide is obtained by coating titanium dioxide with 3-methyl acrylic acid sulfopropyl potassium salt grafted polydopamine. The titanium dioxide has photocatalytic effect and antibacterial property, can catalytically decompose pollutants in sewage, inhibit the breeding of bacteria in water, and can catalytically decompose free formaldehyde in dicyandiamide formaldehyde polycondensate. The modified nano titanium dioxide is loaded on phenolic resin foam, and after calcination, the nano titanium dioxide / foam carbon powder is formed. The large specific surface area and porous property of the foam carbon can increase the capture and fixation of free formaldehyde, and can synergistically accelerate the catalytic degradation of formaldehyde with the titanium dioxide. The dicyandiamide formaldehyde polycondensate grafted with castor oil is in-situ polymerized on the surface of the matrix. The castor oil grafting can significantly improve the dicyandiamide formaldehyde polycondensate, significantly increase the molecular weight, and increase the capture capacity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water treatment agent preparation, and particularly relates to a composite solid decolorizing powder and a preparation method thereof. BACKGROUND

[0002] Water is the source of life, and water treatment is of great significance to the development of industrial production, the improvement of product quality, and the maintenance of ecological balance. There are many types of water treatment agents, including flocculants, settling agents, corrosion inhibitors, bactericides, deodorants, decolorizing agents, cleaning agents, and the like. In practical applications, composite formula water treatment agents are often required for different industrial wastewater, so it is necessary to pay attention to the adverse effects of improper compounding of components and to fully utilize the synergistic effect to increase efficiency.

[0003] The decolorization process of wastewater has always been one of the research hotspots in the field of water treatment. The commonly used decolorizing agent in the industry is activated carbon, but the absorption speed of activated carbon is slow and the consumption is large. Organic decolorizing agents such as dicyandiamide-formaldehyde condensates have high decolorization rates, but the use of pure dicyandiamide increases the cost of decolorization due to its high price, and dicyandiamide-formaldehyde condensates usually have low molecular weights and are not easy to store. Research has found that dicyandiamide-formaldehyde condensates have special functions in removing high-color wastewater. They are polyammonium salt cationic organic compounds that can neutralize the negative charges of dye and chromophore groups in wastewater, making them unstable and forming flocculation bodies that separate from the water, thus completing part of the decolorization function.

[0004] A wastewater decolorizing agent and a preparation method thereof are disclosed in Chinese Patent No. CN117101622B. Attapulgite is selected as the base material, and the specific surface area is low. The loading of silicon dioxide and aluminum oxide on the surface of attapulgite helps to capture free formaldehyde, and the adsorption capacity of attapulgite can be improved by increasing the specific surface area. However, the randomly grown silicon dioxide and aluminum oxide will partially occupy the pores of attapulgite, hindering the diffusion of pollutants and affecting the decolorization adsorption efficiency. SUMMARY

[0005] The purpose of the present application is to provide a composite solid decolorizing powder and a preparation method thereof. The titanium dioxide is coated with 3-methylacrylic acid sulfopropyl potassium salt grafted polydopamine, and then the modified nano-titanium dioxide is loaded on a phenolic resin foam. After calcination, a nano-titanium dioxide / foam carbon powder is formed, and the dicyandiamide-formaldehyde condensate grafted with castor oil is polymerized in situ on the surface of the powder to obtain a composite solid decolorizing powder with large specific surface area and pores. This reduces the diffusion time of pollutants and ensures the decolorization adsorption efficiency in wastewater treatment.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A preparation method of a composite solid decolorizing powder, comprising the following steps:

[0008] Step one: covalently grafting modified nano-titanium dioxide powder and phenolic resin formed by condensation reaction of phenol and formaldehyde to obtain modified nano-titanium dioxide / phenolic resin foam and carbonize the foam to obtain nano-titanium dioxide / foam carbon powder.

[0009] Step two: adding castor oil polyester polyol, N,N-dimethylformamide, nano-titanium dioxide / foam carbon powder, ammonium persulfate and sodium bisulfite into a reaction kettle, then dissolving dicyandiamide formaldehyde prepolymer concentrated solution in tetrahydrofuran and adding the solution into the reaction kettle, stirring under nitrogen atmosphere at 80-90 DEG C and 400-500 r / min for 8-10 h, filtering, washing the filter cake with deionized water and anhydrous ethanol for 2-3 times respectively, vacuum drying at 60-80 DEG C for 1-2 h, and grinding to obtain a composite solid decolorizing powder.

[0010] Further, the amount ratio of castor oil polyester polyol, N,N-dimethylformamide, nano-titanium dioxide / foam carbon powder, ammonium persulfate, sodium bisulfite, dicyandiamide formaldehyde prepolymer concentrated solution and tetrahydrofuran in step two is 40-50 mL: 200-300 mL: 50-60 g: 1-2 g: 1-2 g: 20-30 mL: 200-250 mL.

[0011] Further, the modified nano-titanium dioxide / phenolic resin foam in step one is prepared by the following steps:

[0012] adding formaldehyde solution with a mass fraction of 20-30%, ammonium dihydrogen phosphate, phenol, modified nano-titanium dioxide powder and deionized water into a reaction kettle, stirring at 55-60 DEG C and 500-600 r / min for 1-2 h, then adding sodium hydroxide solution with a mass fraction of 1%, continuing to react for 1-2 h, heating at 95-100 DEG C for 1-2 h, cooling the product to 60-80 DEG C, adjusting the pH value to neutral with hydrochloric acid solution with a concentration of 1 mol / L, and dehydrating by vacuum distillation under a vacuum degree of 0.092-0.095 MPa, mixing the product with Tween 80, n-pentane, concentrated sulfuric acid and deionized water, stirring at 2000-3000 r / min for 15-20 min, transferring the mixture into a mold, foaming and solidifying at 60-80 DEG C for 20-24 h to obtain modified nano-titanium dioxide / phenolic resin foam.

[0013] Further, the amount ratio of formaldehyde solution, ammonium dihydrogen phosphate, phenol, modified nano-titanium dioxide powder, deionized water, sodium hydroxide solution, Tween 80, n-pentane, concentrated sulfuric acid and deionized water is 80-90 mL: 12-14 g: 80-100 g: 15-20 g: 200-220 mL: 10-12 mL: 1-2 mL: 40-50 mL: 4-6 mL: 5-7 mL.

[0014] Further, the modified nano-titanium dioxide powder is prepared by the following steps:

[0015] The nano-titanium dioxide dispersion liquid with a mass fraction of 5-10% and Tris-HCl buffer solution are added into a reaction kettle, stirred at 20-25°C and 400-500 r / min for 30-40 min, then dopamine hydrochloride and 3-methylacrylic acid sulfopropyl potassium salt are added, stirred at 20-25°C and 400-500 r / min for 10-12 h, to obtain the modified nano-titanium dioxide powder.

[0016] Further, the amount ratio of nano-titanium dioxide dispersion liquid, Tris-HCl buffer solution, dopamine hydrochloride and 3-methylacrylic acid sulfopropyl potassium salt is 50-60 mL: 1-2 mL: 0.2-0.5 g: 1-2 g.

[0017] Further, the specific steps of carbonization in step one are as follows:

[0018] The modified nano-titanium dioxide / phenolic resin foam is placed in a tube furnace, heated to 300-350°C at 5-7°C / min under nitrogen protection, kept for 1-2 h, heated to 800-850°C at 6-8°C / min, kept for 1-2 h, converted from nitrogen to carbon dioxide, activated for 2-3 h, then converted from carbon dioxide to nitrogen, naturally cooled to room temperature, ground and crushed, sieved through a 200-300 mesh sieve, to obtain nano-titanium dioxide / foam carbon powder.

[0019] Further, the dicyandiamide formaldehyde prepolymer concentrated solution in step two is prepared by the following steps:

[0020] Acrylamide, dicyandiamide and formaldehyde solution are added into a reaction kettle, stirred at 20-25°C and 400-500 r / min for 30-40 min, then 30-40 wt% hydrochloric acid solution is added, heated to 70-80°C, and the reaction is continued for 40-60 min, then rotary evaporation is performed to concentrate, to obtain the dicyandiamide formaldehyde prepolymer concentrated solution.

[0021] Further, the amount ratio of acrylamide, dicyandiamide, formaldehyde solution and hydrochloric acid solution is 50-60 mL: 60-70 g: 200-220 mL: 1-2 mL.

[0022] The beneficial effects of the present application are:

[0023] 1. The composite solid decolorizing powder prepared by the present application is obtained by coating titanium dioxide with 3-methyl acrylic acid sulfopropyl potassium salt grafted polydopamine, obtaining modified nano titanium dioxide, loading the modified nano titanium dioxide on phenolic resin foam, and forming nano titanium dioxide / foam carbon powder after calcination, and in-situ polymerizing castor oil grafted modified dicyandiamide formaldehyde polycondensate on the surface of the above-mentioned base to obtain the composite solid decolorizing powder, which reduces the diffusion time of pollutants, thereby ensuring its decolorization and adsorption efficiency in wastewater treatment, has high removal rate of COD and ammonia nitrogen, and has certain antibacterial effect.

[0024] 2. The nano titanium dioxide / foam carbon powder of the present application is obtained by calcining modified nano titanium dioxide / phenolic resin foam, and hydrogen ions are released by ammonium dihydrogen phosphate to form a weak acidic environment, promote the polycondensation reaction of phenol and formaldehyde, and n-pentane is used as a physical foaming agent to produce gas and expand to form a foam structure with large specific surface area and porous surface. The surface of the modified nano titanium dioxide contains a large number of polar groups, which can promote the loading of the modified nano titanium dioxide on the phenolic resin foam. Titanium dioxide has photocatalytic effect and antibacterial property, can catalyze the decomposition of pollutants in wastewater, inhibit the growth of bacteria in water, and can catalyze the decomposition of free formaldehyde in dicyandiamide formaldehyde polycondensate. The large specific surface area and porous nature of the foam carbon can increase the capture and fixation of free formaldehyde, and can synergistically accelerate the catalytic degradation of formaldehyde with titanium dioxide, avoiding harm to the water body.

[0025] 3. The titanium dioxide loaded on the surface of the modified nano titanium dioxide / phenolic resin foam exists in the form of polydopamine / 3-methyl acrylic acid sulfopropyl potassium salt coating, which will decompose during calcination. The polydopamine serves as a nitrogen source, and the sulfonic acid group in 3-methyl acrylic acid sulfopropyl potassium salt provides a sulfur source, obtaining sulfur and nitrogen doped nano titanium dioxide / foam carbon powder. After sulfur and nitrogen doping, the band gap of titanium dioxide is reduced, the absorption of visible light is enhanced, and the photocatalytic performance of titanium dioxide is enhanced. Nitrogen doping can significantly increase the antibacterial effect of titanium dioxide, so that the composite solid decolorizing powder has certain antibacterial property when used for water treatment and decolorization.

[0026] 4. Dicyandiamide formaldehyde polycondensate is a traditional cationic polymer, but it has low molecular weight, resulting in short polymer chains, weak adsorption bridging ability, and inability to effectively capture suspended particles or colloids, and contains free formaldehyde in the polymer, and many other shortcomings. Castor oil grafting can significantly improve the dicyandiamide formaldehyde polycondensate by significantly increasing the molecular weight and increasing the capture ability, and the long-chain fatty acids in castor oil polyester polyol can adsorb oil, fat-soluble dyes and organic pollutants in wastewater through hydrophobic interaction. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0028] Embodiment 1: A preparation method of a composite type solid decolorizing powder, comprising the following steps:

[0029] S1: 50 mL of a 5% mass fraction of a nano-titanium dioxide dispersion liquid and 1 mL of a Tris-HCl buffer are added into a reaction kettle, the particle size of the nano-titanium dioxide in the nano-titanium dioxide dispersion liquid is 50-60 nm, stirring is carried out at 20°C and 400 r / min for 30 min, then 0.2 g of dopamine hydrochloride and 1 g of 3-methyl methacrylate sulfopropyl potassium salt are added, stirring is carried out at 20°C and 400 r / min for 18 h, centrifugal washing is carried out, and vacuum drying is carried out until a constant weight is obtained, to obtain a modified nano-titanium dioxide powder.

[0030] Under alkaline conditions, dopamine is first oxidized into dopaminequinone, and is converted into a semiquinone free radical through a single electron exchange reaction. The converted semiquinone free radical can not only carry out a coupling reaction, but also can initiate a free radical polymerization of 3-methyl methacrylate sulfopropyl potassium salt monomers to form a polymer. In the graft polymerization reaction process, a part of dopamine is first polymerized and non-covalently aggregated under alkaline conditions to form water-insoluble polydopamine. Since the polydopamine has strong viscosity, it can be firmly adhered to the surface of the titanium dioxide. Another part of dopamine is converted into a semiquinone free radical, which is used as an initiator to initiate the free radical polymerization of 3-methyl methacrylate sulfopropyl potassium salt monomers to form a polydopamine / 3-methyl methacrylate sulfopropyl potassium salt polymer, which is then adhered to the surface of the titanium dioxide by the polydopamine on the titanium dioxide to form a modified nano-titanium dioxide powder.

[0031] The generated polydopamine / 3-methyl methacrylate sulfopropyl potassium salt polymer can increase steric hindrance and improve the dispersibility of the titanium dioxide. The surface of the coating layer contains a large number of polar groups, which can make the titanium dioxide uniformly loaded on the phenolic resin foam.

[0032] S2: 80 mL of 20% mass fraction formaldehyde solution, 12 g of ammonium dihydrogen phosphate, 80 g of phenol, 15 g of modified nano-titanium dioxide powder and 500 mL of deionized water were added into a reaction kettle, stirred at 55°C and 500 r / min for 1 h, then 10 mL of 1% mass fraction sodium hydroxide solution was added, and the reaction was continued for 1 h, heated at 95°C for 1 h, the product was cooled to 60°C, the pH value was adjusted to neutral with 1 mol / L hydrochloric acid solution, and dehydrated by vacuum distillation under vacuum degree of 0.092 MPa, the product was mixed with 1 mL of Tween 80, 40 mL of n-pentane, 4 mL of concentrated sulfuric acid and 5 mL of deionized water, stirred at 2000 r / min for 15 min, the mixture was transferred into a mold, foamed and solidified at 60°C for 20 h to obtain modified nano-titanium dioxide / phenolic resin foam.

[0033] Ammonium dihydrogen phosphate releases hydrogen ions to form a weak acidic environment, promoting the polycondensation reaction of phenol and formaldehyde, the hydroxyl group ortho and para active sites of phenol undergo nucleophilic addition with the carbonyl group of formaldehyde to generate hydroxymethyl phenol intermediates, n-pentane acts as a physical foaming agent to produce gas and expand to form a foam structure.

[0034] The polydopamine layer in the modified nano-titanium dioxide powder contains active amino groups, which can covalently graft with the hydroxymethyl groups of phenolic resin, allowing titanium dioxide to be uniformly loaded on the phenolic resin foam.

[0035] S3: The modified nano-titanium dioxide / phenolic resin foam was placed in a tube furnace, heated to 300°C at 5°C / min under nitrogen protection, kept for 1 h, heated to 800°C at 6°C / min, kept for 1 h, converted nitrogen to carbon dioxide, activated for 2 h, then converted carbon dioxide to nitrogen, naturally cooled to room temperature, ground and crushed, and sieved through a 200 mesh sieve to obtain nano-titanium dioxide / foam carbon powder.

[0036] The polydopamine and 3-methyl acrylate sulfopropyl potassium salt in the modified nano-titanium dioxide / phenolic resin foam will decompose during calcination, with polydopamine as the nitrogen source and the sulfonic acid group in 3-methyl acrylate sulfopropyl potassium salt providing a sulfur source to obtain nano-titanium dioxide / foam carbon powder.

[0037] S4: 50 mL of acrylamide, 60 g of dicyandiamide and 200 mL of formaldehyde solution were added into a reaction kettle, stirred at 20℃ and 400 r / min for 30 min, then 1 mL of 30 wt% hydrochloric acid solution was added, heated to 70℃, and the reaction was continued for 40 min. After rotary evaporation and concentration, a dicyandiamide formaldehyde prepolymer concentrate was obtained; 40 mL of castor oil polyester polyol, 200 mL of N,N-dimethylformamide, 50 g of nano-titanium dioxide / foamed carbon powder, 1 g of ammonium persulfate and 1 g of sodium bisulfite were added into a reaction kettle, then 20 mL of dicyandiamide formaldehyde prepolymer concentrate dissolved in 200 mL of tetrahydrofuran was added into the reaction kettle, stirred at 80℃ and 400 r / min for 8 h under nitrogen atmosphere, filtered, and the filter cake was washed with deionized water and anhydrous ethanol for 2 times respectively, vacuum dried at 60℃ for 1 h, ground and crushed to obtain a composite solid decolorizing powder.

[0038] The hydroxyl radical ionized oxygen free radicals in the castor oil polyester polyol and the C=C double bonds of the dicyandiamide formaldehyde prepolymer were polymerized under the action of the initiator to form an interpenetrating polymer network.

[0039] Example 2: A preparation method of a composite solid decolorizing powder, comprising the following steps:

[0040] S1: 55 mL of 8% mass fraction nano-titanium dioxide dispersion liquid and 1.2 mL of Tris-HCl buffer were added into a reaction kettle, the particle size of nano-titanium dioxide in the nano-titanium dioxide dispersion liquid was 50-60 nm, stirred at 22.5℃ and 450 r / min for 35 min, then 0.35 g of dopamine hydrochloride and 1.5 g of 3-methyl methacrylic acid sulfopropyl potassium salt were added, stirred at 22.5℃ and 450 r / min for 19 h, centrifuged and washed, vacuum dried to constant weight to obtain a modified nano-titanium dioxide powder.

[0041] S2: 85 mL of 25% mass fraction formaldehyde solution, 13 g of ammonium dihydrogen phosphate, 90 g of phenol, 17.5 g of modified nano-titanium dioxide powder and 525 mL of deionized water were added into a reaction kettle, stirred at 57.5℃ and 550 r / min for 1.5 h, then 11 mL of 1% mass fraction sodium hydroxide solution was added, and the reaction was continued for 1.5 h, heated at 97.5℃ for 1.5 h, the product was cooled to 70℃, the pH value was adjusted to neutral with 1 mol / L hydrochloric acid solution, and dehydrated by reduced pressure distillation under a vacuum degree of 0.0935 MPa, the product was mixed with 1.5 mL of Tween 80, 45 mL of n-pentane, 5 mL of concentrated sulfuric acid and 6 mL of deionized water, stirred at 2500 r / min for 17.5 min, the mixture was transferred into a mold, foamed and solidified at 70℃ for 22 h to obtain a modified nano-titanium dioxide / phenolic resin foam.

[0042] S3: The modified nano-titanium dioxide / phenolic resin foam was placed in a tube furnace, heated to 325℃ at 6℃ / min under nitrogen protection, kept for 1.5h, heated to 825℃ at 7℃ / min, kept for 1.5h, activated for 2.5h by converting nitrogen to carbon dioxide, and then converting carbon dioxide to nitrogen, naturally cooled to room temperature, ground and crushed, and sieved through a 250 mesh sieve to obtain a nano-titanium dioxide / foamed carbon powder.

[0043] S4: 55mL of acrylamide, 65g of dicyandiamide and 210mL of formaldehyde solution were added to a reaction kettle, stirred at 22.5℃ and 450r / min for 35min, then 1.5mL of 35wt% hydrochloric acid solution was added, heated to 75℃, and the reaction was continued for 50min. The dicyandiamide formaldehyde prepolymer concentrate was obtained by rotary evaporation and concentration. 45mL of castor oil polyester polyol, 250mL of N,N-dimethylformamide, 55g of nano-titanium dioxide / foamed carbon powder, 1.5g of ammonium persulfate and 1.5g of sodium bisulfite were added to the reaction kettle, then 25mL of dicyandiamide formaldehyde prepolymer concentrate was dissolved in 225mL of tetrahydrofuran and added to the reaction kettle. The reaction was stirred at 85℃ and 450r / min for 9h under nitrogen atmosphere. The filter cake was washed with deionized water and anhydrous ethanol for 2.5 times respectively, vacuum dried at 70℃ for 1.5h, and ground to obtain a composite solid decolorizing powder.

[0044] Example 3: A preparation method of a composite solid decolorizing powder, comprising the following steps:

[0045] S1: 60mL of 10wt% nano-titanium dioxide dispersion liquid and 2mL of Tris-HCl buffer were added to a reaction kettle, the particle size of nano-titanium dioxide in the nano-titanium dioxide dispersion liquid was 50-60nm, and the mixture was stirred at 25℃ and 500r / min for 40min. Then 0.5g of dopamine hydrochloride and 2g of 3-methylacrylic acid sulfopropyl potassium salt were added, and the mixture was stirred at 25℃ and 500r / min for 20h. The mixture was centrifuged and washed, and vacuum dried to constant weight to obtain a modified nano-titanium dioxide powder.

[0046] S2: 90 mL of 30% mass fraction formaldehyde solution, 14 g of ammonium dihydrogen phosphate, 100 g of phenol, 20 g of modified nano-titanium dioxide powder and 550 mL of deionized water were added into a reaction kettle, stirred at 60°C and 600 r / min for 2 h, then 12 mL of 1% mass fraction sodium hydroxide solution was added, and the reaction was continued for 2 h, heated at 100°C for 2 h, the product was cooled to 80°C, the pH value was adjusted to neutral with 1 mol / L hydrochloric acid solution, and vacuum distillation was carried out at a vacuum degree of 0.095 MPa, dehydrated, mixed with 2 mL of Tween 80, 50 mL of n-pentane, 6 mL of concentrated sulfuric acid and 7 mL of deionized water, stirred at 3000 r / min for 20 min, transferred to a mold, foamed and solidified at 80°C for 24 h, and a modified nano-titanium dioxide / phenolic resin foam was obtained.

[0047] S3: The modified nano-titanium dioxide / phenolic resin foam was placed in a tube furnace, heated to 350°C at 7°C / min under nitrogen protection, kept for 2 h, heated to 850°C at 8°C / min, kept for 2 h, converted nitrogen to carbon dioxide, activated for 3 h, then converted carbon dioxide to nitrogen, naturally cooled to room temperature, ground and crushed, and sieved through a 300 mesh sieve to obtain a nano-titanium dioxide / foam carbon powder.

[0048] S4: 60 mL of acrylamide, 70 g of dicyandiamide and 220 mL of formaldehyde solution were added into a reaction kettle, stirred at 25°C and 500 r / min for 40 min, then 2 mL of 40 wt% hydrochloric acid solution was added, heated to 80°C, and the reaction was continued for 60 min, rotary evaporation was carried out, and concentrated to obtain a dicyandiamide formaldehyde prepolymer concentrate; 50 mL of castor oil polyester polyol, 300 mL of N,N-dimethylformamide, 60 g of nano-titanium dioxide / foam carbon powder, 2 g of ammonium persulfate and 2 g of sodium bisulfite were added into a reaction kettle, then 30 mL of dicyandiamide formaldehyde prepolymer concentrate dissolved in 250 mL of tetrahydrofuran was added into the reaction kettle, stirred at 90°C and 500 r / min for 10 h under nitrogen atmosphere, filtered, the filter cake was washed with deionized water and anhydrous ethanol for 3 times respectively, vacuum dried at 80°C for 2 h, and ground and crushed to obtain a composite solid decolorizing powder.

[0049] Comparative Example 1: On the basis of Example 3, the nano-titanium dioxide / foam carbon powder in step S4 was replaced by attapulgite, and the remaining steps were unchanged to obtain a composite solid decolorizing powder.

[0050] Comparative Example 2: On the basis of Example 3, the modified nano-titanium dioxide powder in step S2 was replaced by the titanium dioxide powder in step S1 without treatment, and the remaining steps were unchanged to obtain a composite solid decolorizing powder.

[0051] Comparative Example 3: On the basis of Example 3, the castor oil polyester polyol in step S4 was removed, and the remaining steps were unchanged to obtain a composite solid decolorizing powder.

[0052] In the examples and comparative examples:

[0053] The castor oil polyester polyol was purchased from Hubei Langbowan Biomedicine Co., Ltd.

[0054] 3-methacrylate sulfopropyl potassium salt was purchased from Shanghai Maikelin Biochemical Technology Co., Ltd.

[0055] The composite solid decolorizing powder obtained in Examples 1-3 and Comparative Examples 1-3 was tested for performance.

[0056] 1. Decolorization rate: In wastewater with a K-type reactive dye concentration of 1000 mg / L, the composite solid decolorizing powder in the examples and comparative examples was added in an amount of 200 mg / L, and then the dilution factor method was used to determine the colority, and the calculation formula for the decolorization rate was: F / % = [(U0-U1) / U0]x100%; wherein F is the decolorization rate, U0 is the colority before wastewater treatment, and U1 is the colority after wastewater treatment.

[0057] 2. COD removal rate: In wastewater with a COD concentration of 900 mg / L, the composite solid decolorizing powder in the examples and comparative examples was added in an amount of 200 mg / L, and the potassium dichromate method was used to test the COD content before and after wastewater treatment, and the calculation formula for the COD removal rate was: c / % = [(C0-C1) / C0]x100%; wherein c is the COD removal rate, C0 is the colority before wastewater treatment, and C1 is the colority after wastewater treatment.

[0058] 3. Ammonia nitrogen removal rate: In wastewater with an ammonia nitrogen content of 550 mg / L, the composite solid decolorizing powder in the examples and comparative examples was added in an amount of 200 mg / L, and the spectrophotometric method was used to test the ammonia nitrogen content before and after wastewater treatment, and the calculation formula for the ammonia nitrogen removal rate was: n / % = [(N0-N1) / N0]x100%.

[0059] 4. Bacteriostatic circle test: A certain amount of Staphylococcus aureus and Escherichia coli were suspended in 2 mL of sterile DPBS, 10 mL of LB was added, and incubated at 37°C for 12 h, then mixed with 50 mL of LB, and incubated in a shaking bed at a vibration rate of 120 r / min for 8 h. Nutrient agar was dissolved in deionized water, and the pH value was adjusted to neutral, and sterilization was carried out in a sterilization pot. When the temperature dropped to 50°C, the agar was poured into a culture dish without bacteria, and the agar plate was formed. 0.2 mL of the test sample was added to the agar plate, and the plate was incubated at 37°C for 24 h. The diameter of the inhibition zone was measured, and the inhibition zone was calculated according to the formula: inhibition zone / % = (diameter of inhibition zone / diameter of control group) x 100%. 6Staphylococcus aureus or Escherichia coli suspension of CFU / mL, mixed with 10 mL agar solution at 50°C, evenly spread on a solidified agar plate, after mixing evenly, pour into the plate, place horizontally, after standing, use. Use a sterilized punch to punch holes on the plate, accurately add 30 mg of the sample to be tested in the hole, after 24 h of culture, measure the diameter of the inhibition zone with a ruler, which is used as a measure to determine the strength of the antibacterial property of the sample. The diameter of the inhibition zone represents the antibacterial ability of the preparation, and the results are shown in Table 1:

[0060] Table 1 Performance test results of composite solid decolorizing powder

[0061]

[0062]

[0063] As can be seen from Table 1, the decolorization rate, COD removal rate, ammonia nitrogen removal rate, and inhibition zone of the composite solid decolorizing powder obtained in Examples 1-3 are significantly better than those of the comparative examples, indicating that the composite solid decolorizing powder prepared in the present application has high decolorization efficiency, high COD and ammonia nitrogen removal rate, and certain antibacterial effect.

[0064] In Comparative Example 1, the nano-titanium dioxide / foam carbon powder is replaced with attapulgite. As can be seen from Table 1, after being replaced with attapulgite, the performance tests are significantly decreased, indicating that the surface active sites provided by attapulgite as the matrix cannot effectively load dicyandiamide formaldehyde polycondensate, and after loading aluminum oxide and silicon dioxide, the remaining pores and active sites are insufficient to assist dicyandiamide formaldehyde polycondensate in treating wastewater.

[0065] In Comparative Example 2, the modified nano-titanium dioxide powder is replaced with titanium dioxide powder. The modified nano-titanium dioxide exists in the form of polydopamine / 3-methyl acrylic acid sulfopropyl potassium salt coating, which will decompose during calcination. The polydopamine is used as a nitrogen source, and the sulfonic acid group in 3-methyl acrylic acid sulfopropyl potassium salt provides a sulfur source, obtaining sulfur and nitrogen doped nano-titanium dioxide / foam carbon powder. After sulfur and nitrogen doping, the band gap of titanium dioxide is reduced, the absorption of visible light is enhanced, and the photocatalytic performance of titanium dioxide is enhanced. Nitrogen doping can significantly increase the antibacterial effect of titanium dioxide, so that the composite solid decolorizing powder has certain antibacterial property during water treatment and decolorization.

[0066] In Comparative Example 3, the castor oil polyester polyol is removed. Castor oil grafting can significantly improve the dicyandiamide formaldehyde polycondensate, significantly increase the molecular weight, and increase the capture ability. The long-chain fatty acids in the castor oil polyester polyol can adsorb oil, fat-soluble dyes, and organic pollutants in wastewater through hydrophobic interaction.

[0067] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application.

Claims

1. A method for preparing a composite solid decolorizing powder, characterized in that, Includes the following steps: Step 1: Covalently graft modified nano-titanium dioxide powder and phenolic resin formed by the polycondensation reaction of phenol and formaldehyde to obtain modified nano-titanium dioxide / phenolic resin foam, and then carbonize it to obtain nano-titanium dioxide / foam carbon powder. Step 2: Castor oil polyester polyol, dimethylformamide, nano titanium dioxide / foamed carbon powder, ammonium persulfate and sodium bisulfite are added to the reaction vessel. Then, the dicyandiamide formaldehyde prepolymer concentrate is dissolved in tetrahydrofuran and added to the reaction vessel. Under a nitrogen atmosphere, the mixture is stirred at 80-90℃ and 400-500r / min for 8-10h. After filtration, washing, vacuum drying, and grinding, a composite solid decolorizing powder is obtained. The modified nano-titanium dioxide / phenolic resin foam described in step one is prepared through the following steps: Add 20-30 wt% formaldehyde solution, ammonium dihydrogen phosphate, phenol, modified nano titanium dioxide powder, and deionized water to a reaction vessel. Stir at 55-60℃ and 500-600 r / min for 1-2 h. Then add 1 wt% sodium hydroxide solution and continue the reaction for 1-2 h. Heat at 95-100℃ for 1-2 h. Cool the product to 60-80℃ and adjust the pH to neutral with 1 mol / L hydrochloric acid solution. Dehydrate by vacuum distillation at 0.092-0.095 MPa. Mix the product with Tween 80, n-pentane, concentrated sulfuric acid, and deionized water. Stir at 2000-3000 r / min for 15-20 min. Transfer the mixture to a mold and foam and cure at 60-80℃ for 20-24 h to obtain modified nano titanium dioxide / phenolic resin foam. The modified nano-titanium dioxide powder is prepared through the following steps: Add 5-10 wt% of nano-titanium dioxide dispersion and Tris-HCl buffer to a reaction vessel, stir at 20-25℃ and 400-500 r / min for 30-40 min, then add dopamine hydrochloride and potassium sulfonyl methacrylate, stir at 20-25℃ and 400-500 r / min for 10-12 h to obtain modified nano-titanium dioxide powder; The dicyandiamide-formaldehyde prepolymer concentrate described in step two is prepared through the following steps: Acrylamide, dicyandiamide, and formaldehyde solution are added to a reaction vessel and stirred for 30-40 minutes at 20-25℃ and 400-500 r / min. Then, 30-40 wt% hydrochloric acid solution is added, heated to 70-80℃, and the reaction is continued for 40-60 minutes. The mixture is then evaporated by rotary evaporation and concentrated to obtain a concentrated dicyandiamide-formaldehyde prepolymer solution.

2. The method for preparing a composite solid decolorizing powder according to claim 1, characterized in that, In step two, the ratio of castor oil polyester polyol, dimethylformamide, nano titanium dioxide / foamed carbon powder, ammonium persulfate, sodium bisulfite, dicyandiamide formaldehyde prepolymer concentrate, and tetrahydrofuran is 40-50 mL: 200-300 mL: 50-60 g: 1-2 g: 1-2 g: 20-30 mL: 200-250 mL.

3. The method for preparing a composite solid decolorizing powder according to claim 1, characterized in that, The ratio of formaldehyde solution, ammonium dihydrogen phosphate, phenol, modified nano titanium dioxide powder, deionized water, sodium hydroxide solution, Tween 80, n-pentane, concentrated sulfuric acid, and deionized water is 80-90mL: 12-14g: 80-100g: 15-20g: 200-220mL: 10-12mL: 1-2mL: 40-50mL: 4-6mL: 5-7mL.

4. The method for preparing a composite solid decolorizing powder according to claim 1, characterized in that, The ratio of the nano-titanium dioxide dispersion, Tris-HCl buffer, dopamine hydrochloride, and potassium sulfopropyl 3-methacrylate is 50-60 mL: 1-2 mL: 0.2-0.5 g: 1-2 g.

5. The method for preparing a composite solid decolorizing powder according to claim 1, characterized in that, The specific steps of carbonization described in step one are as follows: The modified nano-titanium dioxide / phenolic resin foam is placed in a tube furnace and heated to 300-350℃ at 5-7℃ / min under nitrogen protection, and held for 1-2 hours. Then it is heated to 800-850℃ at 6-8℃ / min and held for 1-2 hours to convert nitrogen into carbon dioxide. After activation for 2-3 hours, the carbon dioxide is converted back into nitrogen. The mixture is then allowed to cool naturally, ground, and pulverized, and passed through a 200-300 mesh sieve to obtain nano-titanium dioxide / foamed carbon powder.

6. The method for preparing a composite solid decolorizing powder according to claim 1, characterized in that, The ratio of acrylamide, dicyandiamide, formaldehyde solution, and hydrochloric acid solution used is 50-60 mL: 60-70 g: 200-220 mL: 1-2 mL.

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