A sulfur-iron composite polyurethane foam filler, its preparation method and application

Abstract

The present invention belongs to the technical field of polyurethane foam fillers, and more particularly to a sulfur-iron composite polyurethane foam filler and its preparation method and application. The preparation method includes: respectively mixing sulfur powder, iron powder and activated carbon powder with an alcohol solution of a silane coupling agent for the first time, performing heating modification, and obtaining modified sulfur powder, modified iron powder and modified activated carbon powder respectively; after the modified sulfur powder, modified iron powder and modified activated carbon powder are preliminarily mixed with ethylene glycol, the obtained preliminarily mixed material is mixed with 4,4'-diphenylmethane diisocyanate and a retarder for the second time, and a first prepolymerization reaction is performed to obtain the sulfur-iron composite polyurethane prepolymer; the sulfur-iron composite polyurethane prepolymer, 1,4-butanediol, 4,4'-diphenylmethane diisocyanate and an amine tin catalyst are mixed for the third time, and foaming reaction and curing are performed in sequence to obtain a sulfur-iron composite polyurethane foam filler. The modified component in the sulfur-iron composite polyurethane foam filler prepared by the present invention can be evenly dispersed inside the filler.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane foam fillers, and in particular relates to a sulfide-iron composite polyurethane foam filler and a preparation method and application thereof. Background Art

[0002] The pollution of water resources by urban sewage is receiving increasing attention, especially the pollution of water resources by plant nutrients such as nitrogen and phosphorus. Nitrogen and phosphorus are important nutrients for organisms. When they enter water bodies with sewage, they can cause eutrophication of the water bodies. This causes algae to multiply in large numbers in the water, leading to the deterioration of the water ecological environment, fish deaths, and the generation of foul odors. Currently, the mainstream method for treating nitrogen and phosphorus pollutants is still biological methods, but with the improvement of national and local emission standards, traditional biological methods are often unsatisfactory. Therefore, adding biological fillers during the wastewater treatment process to enhance the metabolic activity and shock resistance of microorganisms and improve the efficiency of biological denitrification is one of the effective means to strengthen the biological treatment of wastewater.

[0003] Polyurethane foam carriers are ideal microbial growth media, featuring high porosity and high specific surface area for microbial immobilization. They also possess excellent mechanical strength and are relatively low cost. Polyurethane-immobilized microorganisms overcome the shortcomings of traditional activated sludge wastewater treatment methods, improving the concentration and purity of microorganisms within bioreactors while maintaining the efficiency and stability of bacterial strains. They are easy to control and facilitate the removal of nitrogen, high-concentration organic matter, and certain difficult-to-degrade substances.

[0004] Anaerobic ammonium oxidation (ANAMMOX) and sulfur autotrophic denitrification (SOD) are both currently researched within the field of water treatment and denitrification. In principle, the two processes complement each other and share similar habitats, so coupling them can yield ideal denitrification results. However, the key to their symbiosis lies in SOD, but sulfur particles, due to their physical properties, are generally not easily utilized by microorganisms. Therefore, to promote better coupling between ANAMMOX and SOD, ferrous sulfur is often incorporated into polyurethane foam to create a modified polyurethane foam filler.

[0005] However, the current preparation of modified polyurethane foam fillers usually adopts a one-step method, that is, mixing the components and raw materials for preparation. For example, Chinese patent application number CN201710957354.9 directly mixes inorganic particles with raw materials and then foams them to prepare polyurethane foam. The above method cannot evenly distribute the modified components inside the filler. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a sulfur-iron composite polyurethane foam filler and its preparation method and application. The modified components (sulfur, iron and activated carbon) in the sulfur-iron composite polyurethane foam filler prepared by the preparation method provided by the present invention can be uniformly dispersed inside the filler.

[0007] In order to achieve the above objectives, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a sulfur-iron composite polyurethane foam filler, comprising the following steps:

[0009] The sulfur powder, iron powder and activated carbon are first mixed with an alcohol solution of a silane coupling agent, and then heated for modification to obtain modified sulfur powder, modified iron powder and modified activated carbon respectively;

[0010] After the modified sulfur powder, modified iron powder, modified activated carbon and ethylene glycol are preliminarily mixed, the obtained preliminarily mixed material is mixed with 4,4'-diphenylmethane diisocyanate and a retarder for a second time, and a first prepolymerization reaction is carried out to obtain the sulfur-iron composite polyurethane prepolymer;

[0011] The sulfide-iron composite polyurethane prepolymer, 1,4-butanediol, 4,4'-diphenylmethane diisocyanate and amine tin catalyst are mixed for a third time, and foaming reaction and curing are carried out in sequence to obtain the sulfide-iron composite polyurethane foam filler.

[0012] Preferably, the mass ratio of the modified sulfur powder to the modified iron powder is 10-15:5-10; the mass ratio of the modified sulfur powder to the modified activated carbon powder is 10-15:1-3.

[0013] Preferably, the mass concentration of the silane coupling agent in the alcohol solution of the silane coupling agent is 1.8-2.2%, the mass ratio of the sulfur powder to the alcohol solution of the silane coupling agent is 3-7:100; the mass ratio of the iron powder to the alcohol solution of the silane coupling agent is 3-7:100; and the mass ratio of the activated carbon to the alcohol solution of the silane coupling agent is 3-7:100.

[0014] Preferably, during the second mixing, the mass ratio of the modified sulfur powder to the 4,4'-diphenylmethane diisocyanate is 1:3-6; the mass ratio of the ethylene glycol to the 4,4'-diphenylmethane diisocyanate is 1:0.2-0.8.

[0015] Preferably, the temperature of the first prepolymerization reaction is 80-85° C., and the holding time is 1.5-2 hours.

[0016] Preferably, during the third mixing, the mass ratio of the sulfide-iron composite polyurethane prepolymer to the 1,4-butanediol is 1:45-55; the mass ratio of the sulfide-iron composite polyurethane prepolymer to the 4,4'-diphenylmethane diisocyanate is 1:25-45.

[0017] Preferably, the temperature of the foaming reaction is 90-110° C., and the insulation time is 10-20 minutes.

[0018] Preferably, the curing temperature is 75-85° C., and the holding time is 10-12 hours.

[0019] The present invention also provides the ferrous sulfide composite polyurethane foam filler prepared by the above-mentioned preparation method.

[0020] The present invention also provides the ferrous sulfide composite polyurethane foam filler prepared by the above-mentioned preparation method or the use of the ferrous sulfide composite polyurethane foam filler in sewage treatment.

[0021] The invention provides a method for preparing a sulfur-iron composite polyurethane foam filler. The method comprises the following steps: firstly mixing sulfur powder, iron powder, activated carbon powder and an alcohol solution of a silane coupling agent, and performing heating modification to obtain modified sulfur powder, modified iron powder and modified activated carbon powder respectively; firstly mixing the modified sulfur powder, modified iron powder, modified activated carbon powder and ethylene glycol, and then secondly mixing the obtained primary mixture with 4,4'-diphenylmethane diisocyanate and a retarder to perform a first prepolymerization reaction to obtain the sulfur-iron composite polyurethane prepolymer; and thirdly mixing the sulfur-iron composite polyurethane prepolymer, 1,4-butanediol, 4,4'-diphenylmethane diisocyanate and an amine tin catalyst, and sequentially performing foaming reaction and curing to obtain the sulfur-iron composite polyurethane foam filler. The present invention first performs surface modification treatment on inorganic particles (sulfur powder, iron powder and activated carbon powder) to enable them to have better affinity with ethylene glycol. Then, the inorganic particles are sequentially mixed with ethylene glycol and 4,4'-diphenylmethane diisocyanate. Since the inorganic particles are relatively evenly distributed in the ethylene glycol, after the 4,4'-diphenylmethane diisocyanate is added, the prepolymerization reaction of the 4,4'-diphenylmethane diisocyanate with the ethylene glycol is directly carried out on the surface of the inorganic particles. Therefore, the uniform distribution of the inorganic particles in the prepolymer can be ensured. At the same time, a retarder is added to provide sufficient time for the obtained prepolymer to be deposited and tightly adhered to the surface of the inorganic particles. Then, the present invention uses the generated organic sulfide-iron composite polyurethane prepolymer as a raw material, mixes it with 1,4-butanediol and 4,4'-diphenylmethane diisocyanate, and foams it to obtain a sulfide-iron composite polyurethane foam filler. The organic sulfide-iron composite polyurethane prepolymer, 4,4'-diphenylmethane diisocyanate, and 1,4-butanediol have good compatibility. During the foaming reaction, it can ensure that the inorganic components in the filler are not easily lost, thereby ensuring the content of the inorganic components in the filler. In addition, inorganic particles are first foamed to obtain a sulfide-iron composite polyurethane prepolymer, and the sulfide-iron composite polyurethane prepolymer is used as a raw material for in-situ polymerization to obtain the final product, which can effectively improve the uniformity of the inorganic particles in the finished product. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the effect diagram of reactor R1 treating nitrogen-containing wastewater;

[0023] Figure 2This is the effect diagram of reactor R2 treating nitrogen-containing wastewater;

[0024] Figure 3 This is the effect diagram of reactor R3 treating nitrogen-containing wastewater;

[0025] Figure 4 is the sulfur element concentration-radius relationship curve;

[0026] Figure 5 This is the iron concentration-radius relationship curve. DETAILED DESCRIPTION

[0027] The present invention provides a method for preparing a sulfide-iron composite polyurethane foam filler, comprising the following steps:

[0028] The sulfur powder, iron powder and activated carbon are first mixed with an alcohol solution of a silane coupling agent, and then heated for modification to obtain modified sulfur powder, modified iron powder and modified activated carbon respectively;

[0029] After the modified sulfur powder, modified iron powder, modified activated carbon and ethylene glycol are preliminarily mixed, the obtained preliminarily mixed material is mixed with 4,4'-diphenylmethane diisocyanate and a retarder for a second time, and a first prepolymerization reaction is carried out to obtain the sulfur-iron composite polyurethane prepolymer;

[0030] The sulfide-iron composite polyurethane prepolymer, 1,4-butanediol, 4,4'-diphenylmethane diisocyanate and amine tin catalyst are mixed for a third time, and foaming reaction and curing are carried out in sequence to obtain the sulfide-iron composite polyurethane foam filler.

[0031] In the present invention, unless otherwise specified, the components are commercially available products well known to those skilled in the art.

[0032] The invention first mixes sulfur powder, iron powder, activated carbon powder and an alcohol solution of a silane coupling agent, and then heats and modifies them to obtain modified sulfur powder, modified iron powder and modified activated carbon powder respectively.

[0033] In the present invention, prior to the first mixing, the sulfur powder, iron powder, and activated carbon powder are preferably dried. The drying temperature is preferably 100°C and the drying time is preferably 2 hours. The particle size of the sulfur powder, iron powder, and activated carbon powder is preferably independently 5 to 100 μm, more preferably 10 μm.

[0034] In the present invention, the alcohol solution of the silane coupling agent comprises a silane coupling agent and an alcohol solvent. In the present invention, the silane coupling agent preferably comprises one or more of 3-(2,3-epoxypropyloxy)propyltrimethoxysilane, 3-(2,3-epoxypropyloxy)propyltriethoxysilane, 3-(2,3-epoxypropyloxy)propylmethyldiethoxysilane, 3-(2,3-epoxypropyloxy)propylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane and 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, more preferably 3-(2,3-epoxypropyloxy)propyltrimethoxysilane. In the present invention, the alcohol solvent preferably includes one or more of anhydrous ethanol, isoamyl alcohol, and n-hexanol, more preferably anhydrous ethanol. In the present invention, the mass concentration of the silane coupling agent in the alcohol solution of the silane coupling agent is preferably 1.8-2.2%, more preferably 2%. In the present invention, the mass ratio of the sulfur powder to the alcohol solution of the silane coupling agent is preferably 3-7:100, more preferably 5:100. In the present invention, the mass ratio of the iron powder to the alcohol solution of the silane coupling agent is preferably 3-7:100, more preferably 5:100. In the present invention, the mass ratio of the activated carbon to the alcohol solution of the silane coupling agent is preferably 3-7:100, more preferably 5:100.

[0035] In the present invention, the first mixing is preferably ultrasonic stirring, and the first mixing conditions include: the temperature is preferably room temperature; the time is preferably 1.5 to 2 hours, more preferably 1.7 to 1.8 hours; and the rotation speed is preferably 1000 rpm.

[0036] In the present invention, the temperature of the heating modification is preferably 75 to 85° C., more preferably 80° C., and the time is preferably 1.5 to 2 hours, more preferably 1.55 to 1.95 hours.

[0037] In the present invention, after the heating modification, the product after the heating modification is preferably cooled and filtered in sequence, and the obtained solid phase is washed, dried and crushed in sequence.

[0038] In the present invention, the cooling is not specifically limited, and cooling to room temperature can be performed using operations well known in the art. In the present invention, the filtration is preferably vacuum filtration. In the present invention, the washing is preferably washing with anhydrous ethanol. In the present invention, the drying is not specifically limited, and the ethanol can be removed using operations well known to those skilled in the art. In the present invention, the crushing is not specifically limited, and the dried solid phase can be crushed to a particle size of less than 150 mesh using operations well known to those skilled in the art.

[0039] After obtaining modified sulfur powder, modified iron powder and modified activated carbon powder, the present invention performs a primary mixing of the modified sulfur powder, modified iron powder, modified activated carbon powder and ethylene glycol, and then performs a second mixing of the primary mixture with 4,4'-diphenylmethane diisocyanate and a retarder to perform a first prepolymerization reaction to obtain the sulfur-iron composite polyurethane prepolymer.

[0040] In the present invention, the retarder is preferably a ketone compound; the ketone compound is preferably acetone. In the present invention, the mass ratio of the 4,4'-diphenylmethane diisocyanate to the retarder is preferably 1:1-2, more preferably 1:1.5. In the present invention, the mass ratio of the modified sulfur powder to the modified iron powder is preferably 10-15:5-10, more preferably 14:5; the mass ratio of the modified sulfur powder to the modified activated carbon powder is preferably 5-10:1-3, more preferably 5:1. In the present invention, the mass ratio of the modified sulfur powder to 4,4'-diphenylmethane diisocyanate is preferably 1:3-6, more preferably 1:5; the mass ratio of the ethylene glycol to the 4,4'-diphenylmethane diisocyanate is preferably 1:0.2-0.8, more preferably 1:0.67.

[0041] In the present invention, the initial mixing method is preferably ultrasonic stirring, and the initial mixing conditions preferably include: temperature is preferably 80-85° C., more preferably 81-84° C.; time is preferably 0.4-0.6 h, more preferably 0.5 h.

[0042] In the present invention, the temperature of the first prepolymerization reaction is preferably 80-85°C, more preferably 82°C, and the time is preferably 1.5-2 hours, more preferably 1.55-1.95 hours. In the present invention, the heating rate to the temperature of the first prepolymerization reaction is preferably 2-5°C / min, more preferably 3°C / min.

[0043] After the first prepolymerization reaction, the present invention preferably further comprises drying the system obtained from the first prepolymerization reaction. In the present invention, the drying is not specifically limited, and the organic solvent doped in the product can be removed by an operation well known to those skilled in the art.

[0044] After obtaining the ferrous sulfate composite polyurethane prepolymer, the present invention thirdly mixes the ferrous sulfate composite polyurethane prepolymer, 1,4-butanediol, 4,4'-diphenylmethane diisocyanate and an amine tin catalyst, and sequentially performs foaming reaction and curing to obtain a modified polyurethane foam filler.

[0045] In the present invention, the amine tin catalyst preferably includes a tertiary amine and dibutyltin dilaurate; the mass ratio of the tertiary amine to dibutyltin dilaurate is preferably 1:1.

[0046] In the present invention, the mass ratio of the sulfide-iron composite polyurethane prepolymer and 1,4-butanediol is preferably 1:45-55, more preferably 1:50; the mass ratio of the sulfide-iron composite polyurethane prepolymer and 4,4'-diphenylmethane diisocyanate is preferably 1:25-45, more preferably 1:30; the mass ratio of the sulfide-iron composite polyurethane prepolymer and the amine tin catalyst is preferably 1:0.1-0.3, more preferably 1:0.2.

[0047] In the present invention, the third mixing is not specifically limited, and the materials can be mixed uniformly using operations well known to those skilled in the art.

[0048] In the present invention, the foaming reaction is preferably carried out at a temperature of 90 to 110°C, more preferably 100°C, and for a time of 10 to 20 minutes, more preferably 15 minutes. In the present invention, the foaming reaction is preferably carried out under stirring, and the stirring speed is preferably 1000 to 2000 rpm, more preferably 1500 rpm.

[0049] In the present invention, the curing temperature is preferably 75-85°C, more preferably 80°C, and the curing time is preferably 10-12 hours, more preferably 11 hours. In the present invention, the curing agent is preferably toluene-2,4-diisocyanate. In the present invention, the curing is preferably carried out in an oven.

[0050] The present invention also provides a sulfur-iron composite polyurethane foam filler prepared by the above-mentioned preparation method. In the present invention, the total mass of sulfur, iron and activated carbon in the sulfur-iron composite polyurethane foam filler is preferably 0.5-5% of the mass of the sulfur-iron composite polyurethane foam filler, more preferably 2-4%. In the present invention, the specific surface area of the sulfur-iron composite polyurethane foam filler is preferably 7-9 m 2 / g, more preferably 8m 2 / g.

[0051] The present invention also provides application of the above-mentioned ferrous sulfur composite polyurethane foam filler in sewage treatment.

[0052] The polyurethane foam provided by the present invention has a large specific surface area and good bioburden performance, providing a suitable environment for the growth of microorganisms. The addition of iron can promote the metabolic activity of microorganisms, improve the strength of the polyurethane foam skeleton, and enhance the impact resistance of the filler. The addition of sulfur can provide an electron donor for sulfur autotrophic denitrifying bacteria, and the filler also has a certain slow-release performance, which has a certain guarantee on the service life. The addition of activated carbon can form a chemical battery with iron, so that countless micro batteries are formed inside the filler. 2+At the same time, the pollutants caused by insufficient front-end reaction in the actual process can be degraded by micro-batteries, avoiding the impact on the coupling of anaerobic ammonia oxidation and sulfur autotrophic denitrification.

[0053] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1

[0055] Iron powder with a particle size of 10 μm, sulfur powder with a particle size of 10 μm, and activated carbon powder with a particle size of 10 μm were dried at 100° C. to obtain dry iron powder, dry sulfur powder, and dry activated carbon powder;

[0056] In parts by mass, 5 parts of dry sulfur powder, 5 parts of dry iron powder and 5 parts of dry activated carbon powder and 100 parts of 2wt% 3-(2,3-epoxypropoxy)propyltrimethoxysilane ethanol solution were ultrasonically stirred in a three-necked flask for 2 hours, heated to 80°C, heated for modification for 2 hours, and then cooled to room temperature, vacuum filtered, washed with anhydrous ethanol and dried, and passed through a 150-mesh sieve to obtain modified sulfur powder, modified iron powder and modified activated carbon.

[0057] 2.8 parts of modified sulfur powder, 1 part of modified iron powder and 0.2 parts of modified activated carbon were mixed with 15 parts of ethylene glycol at 80° C. and ultrasonically stirred for 0.5 h. Then, 10 parts of 4,4'-diphenylmethane diisocyanate and 15 parts of acetone were added for a second mixing, and then a first prepolymerization reaction was carried out at 80° C. for 2 h. After the reaction, the product was dried to obtain a sulfur-iron composite polyurethane prepolymer.

[0058] In parts by mass, 1 part of a sulfur-iron composite polyurethane prepolymer, 30 parts of 4,4'-diphenylmethane diisocyanate, 50 parts of 1,4-butanediol and 0.2 parts of a tertiary amine and a mixture of dibutyltin dilaurate (mass ratio 1:1) are mixed for the third time and then foamed at a foaming temperature of 100°C, a rotation speed of 1500rpm, and a time of 15min. The mixture is then placed at 80°C for curing for 12h to obtain a sulfur-iron composite polyurethane foam filler.

[0059] The total mass of sulfur, iron and activated carbon in the sulfur-iron composite polyurethane foam filler in Example 1 is 3.67% of the sulfur-iron composite polyurethane foam filler.

[0060] Example 2

[0061] Iron powder with a particle size of 10 μm, sulfur powder with a particle size of 10 μm, and activated carbon powder with a particle size of 10 μm were dried at 100° C. to obtain dry iron powder, dry sulfur powder, and dry activated carbon powder;

[0062] In parts by mass, 5 parts of dry sulfur powder, 5 parts of dry iron powder and 5 parts of dry activated carbon powder and 100 parts of 2wt% 3-(2,3-epoxypropoxy)propyltrimethoxysilane ethanol solution were ultrasonically stirred in a three-necked flask for 2 hours, heated to 80°C, heated for modification for 2 hours, and then cooled to room temperature, vacuum filtered, washed with anhydrous ethanol and dried, and passed through a 150-mesh sieve to obtain modified sulfur powder, modified iron powder and modified activated carbon.

[0063] 2 parts of modified sulfur powder, 1 part of modified iron powder and 0.2 parts of modified activated carbon were mixed with 18 parts of ethylene glycol at 80°C, and ultrasonically stirred for 0.5 hours. Then, 10 parts of 4,4'-diphenylmethane diisocyanate and 15 parts of acetone were added for a second mixing, and then a first prepolymerization reaction was carried out at 80°C for 2 hours. After the reaction, the product was dried to obtain a sulfur-iron composite polyurethane prepolymer.

[0064] In parts by mass, 1 part of a sulfur-iron composite polyurethane prepolymer, 30 parts of 4,4'-diphenylmethane diisocyanate, 50 parts of 1,4-butanediol and 0.2 parts of a tertiary amine and a mixture of dibutyltin dilaurate (mass ratio 1:1) are mixed for the third time and then foamed at a foaming temperature of 100°C, a rotation speed of 1500rpm, and a time of 15min. The mixture is then placed at 80°C for curing for 12h to obtain a sulfur-iron composite polyurethane foam filler.

[0065] The total mass of sulfur, iron and activated carbon in the sulfur-iron composite polyurethane foam filler in Example 2 is 2.88% of the sulfur-iron composite polyurethane foam filler.

[0066] Example 3

[0067] Iron powder with a particle size of 10 μm, sulfur powder with a particle size of 10 μm, and activated carbon powder with a particle size of 10 μm were dried at 100° C. to obtain dry iron powder, dry sulfur powder, and dry activated carbon powder;

[0068] In parts by mass, 5 parts of dry sulfur powder, 5 parts of dry iron powder, 5 parts of dry activated carbon powder and 100 parts of an ethanol solution of 3-(2,3-epoxypropoxy)propyltrimethoxysilane with a concentration of 2wt% were ultrasonically stirred in a three-necked flask for 2 hours, then heated to 80°C and heated for modification for 2 hours, then cooled to room temperature, vacuum filtered, washed with anhydrous ethanol and dried, and passed through a 150-mesh sieve to obtain modified sulfur powder, modified iron powder and modified activated carbon.

[0069] In parts by mass, 3 parts of modified sulfur powder, 1 part of modified iron powder and 0.2 parts of modified activated carbon were mixed with 13 parts of ethylene glycol at 80°C, and after ultrasonic stirring for 0.5 h, 10 parts of 4,4'-diphenylmethane diisocyanate and 15 parts of acetone were added for a second mixing, and then a first prepolymerization reaction was carried out at 80°C for 2 h; after the reaction, the product was dried to obtain a sulfur-iron composite polyurethane prepolymer.

[0070] In parts by mass, 1 part of a sulfur-iron composite polyurethane prepolymer, 30 parts of 4,4'-diphenylmethane diisocyanate, 50 parts of 1,4-butanediol and 0.2 parts of a tertiary amine and a mixture of dibutyltin dilaurate (mass ratio 1:1) are mixed for the third time and then foamed at a foaming temperature of 100°C, a rotation speed of 1500rpm, and a time of 15min. The mixture is then placed at 80°C for curing for 12h to obtain a sulfur-iron composite polyurethane foam filler.

[0071] The total mass of sulfur, iron and activated carbon in the sulfur-iron composite polyurethane foam filler in Example 3 is 3.92% of the sulfur-iron composite polyurethane foam filler.

[0072] Comparative Example 1

[0073] In parts by mass, 3 parts of sulfur powder with a particle size of 10 μm, 1 part of 10 μm iron powder, 0.2 parts of 10 μm activated carbon powder, 30 parts of 4,4'-diphenylmethane diisocyanate, 50 parts of 1,4-butanediol and 0.2 parts of a mixture of tertiary amine and dibutyltin dilaurate (mass ratio 1:1) are mixed and foamed at a foaming temperature of 100°C, a rotation speed of 1500 rpm, and a time of 15 minutes. The mixture is then placed at 80°C for curing for 12 hours to obtain a sulfur-iron composite polyurethane foam filler.

[0074] Comparative Example 2

[0075] The only difference from Example 1 is that no retarder is added.

[0076] Application Example 1

[0077] The iron-sulfur composite polyurethane foam fillers prepared in Examples 1 to 3 were cut into 30mm*30mm*30mm block fillers, which were then placed into spherical shells. The density of the spherical shells was controlled at 1g / cm 3 The spherical shell is divided into three parts: the upper part, the lower part and the buckle. The shell has several small holes for wastewater to flow through. The upper and lower parts are fixed and closed by buckles. The fillers are placed inside the spherical shell and arranged and stacked in a certain direction.

[0078] The sulphur iron composite polyurethane foam filler with a spherical shell is respectively filled into a fixed-bed biocolumn reactor, and inoculated to enrich and culture sulphur autotrophic denitrifying bacteria and anaerobic ammonia oxidizing bacteria to form a biofilm. After forming a biofilm, a peristaltic pump is used to pass simulated nitrogenous wastewater into the reactor. The simulated nitrogenous wastewater is prepared by sodium nitrate, ammonium sulfate and tap water, and the nitrate nitrogen concentration in the simulated nitrogenous wastewater is 50mg / L and the ammonia nitrogen concentration is 40mg / L. The reactor has an effective volume of 6L, and the entire reaction process is divided into three stages, designated as stages I, II and III. Each stage is run for a period of time, and its hydraulic retention time is 8h, 8h and 4h respectively. The load of the reactor is increased by increasing the concentration of the simulated wastewater and reducing the hydraulic retention time, and stable operation is finally achieved in stages II and III. The reactor corresponding to the sulphur iron composite polyurethane foam filler prepared in Example 1 is designated as reactor R1, the reactor corresponding to the sulphur iron composite polyurethane foam filler prepared in Example 2 is designated as reactor R2, and the reactor corresponding to the sulphur iron composite polyurethane foam filler prepared in Example 3 is designated as reactor R3.

[0079] The results are as follows Figures 1 to 3 As shown. Figures 1 to 3 It can be seen that the effluent effects in the three reactors are all optimal in stage III. Among them, the best effect is reactor R3, with a total nitrogen removal rate of 94.12%. Due to its higher content of electron donors, it creates a better environment for the metabolism of microorganisms; and although the treatment effects of reactors R1 and R2 are not as good as reactor R3 under higher load conditions, the total nitrogen removal rates have reached more than 90%, and the effect is better than reactor R3 under relatively low loads (stage II). The examples prove that the sulfur-iron composite polyurethane foam filler provided by the present invention can achieve relatively excellent denitrification effects in the deep denitrification of sewage, especially for the secondary effluent of urban sewage, and has high practical utilization value.

[0080] test:

[0081] The present invention conducted mapping element analysis on the sulfur-iron composite polyurethane foam filler prepared in Example 1. Surface scanning was performed on several different areas of the same filler (image resolution 256×200 pixels, frame number 256) to obtain element surface distribution images. With the filler center as the center of the circle, the element distribution at different radii was mapped to obtain the element concentration-radius relationship curve. Figures 4-5 ,from Figures 4-5 It can be seen that the sulfur and iron in the sulfur-iron composite polyurethane foam filler prepared in Example 1 are evenly distributed.

[0082] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a sulfide-iron composite polyurethane foam filler, characterized in that: The following steps are involved: The sulfur powder, iron powder and activated carbon are first mixed with an alcohol solution of a silane coupling agent, and then heated for modification to obtain modified sulfur powder, modified iron powder and modified activated carbon respectively; After the modified sulfur powder, modified iron powder, modified activated carbon and ethylene glycol are initially mixed, the resulting primary mixture is secondarily mixed with 4,4'-diphenylmethane diisocyanate and a retarder to carry out a first prepolymerization reaction to obtain the sulfur-iron composite polyurethane prepolymer; the mass ratio of the modified sulfur powder to the modified iron powder is 10-15:5-10; the mass ratio of the modified sulfur powder to the modified activated carbon powder is 10-15:1-3; during the second mixing, the mass ratio of the modified sulfur powder to the 4,4'-diphenylmethane diisocyanate is 1:3-6; the mass ratio of the ethylene glycol to the 4,4'-diphenylmethane diisocyanate is 1:0.2-0.8; The sulfide-iron composite polyurethane prepolymer, 1,4-butanediol, 4,4'-diphenylmethane diisocyanate and amine tin catalyst are mixed for the third time, and foaming reaction and curing are carried out in sequence to obtain a sulfide-iron composite polyurethane foam filler; during the third mixing, the mass ratio of the sulfide-iron composite polyurethane prepolymer to the 1,4-butanediol is 1:45-55; the mass ratio of the sulfide-iron composite polyurethane prepolymer to the 4,4'-diphenylmethane diisocyanate is 1:25-45.

2. The preparation method according to claim 1, characterized in that The mass concentration of the silane coupling agent in the alcohol solution of the silane coupling agent is 1.8-2.2%, the mass ratio of the sulfur powder to the alcohol solution of the silane coupling agent is 3-7:100; the mass ratio of the iron powder to the alcohol solution of the silane coupling agent is 3-7:100; and the mass ratio of the activated carbon to the alcohol solution of the silane coupling agent is 3-7:

100.

3. The preparation method according to claim 1, characterized in that The temperature of the first prepolymerization reaction is 80-85° C., and the insulation time is 1.5-2 hours.

4. The preparation method according to claim 1, characterized in that The temperature of the foaming reaction is 90-110° C., and the insulation time is 10-20 minutes.

5. The preparation method according to claim 1, characterized in that The curing temperature is 75-85° C., and the heat preservation time is 10-12 hours.

6. Sulfur-iron composite polyurethane foam filler prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the ferrous sulfide composite polyurethane foam filler prepared by the preparation method according to any one of claims 1 to 5 or the ferrous sulfide composite polyurethane foam filler according to claim 6 in sewage treatment.

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