Safe scavenger for inflammable and virulent hydrogen sulfide and preparation method of safe scavenger

Abstract

The invention relates to a safe scavenger for inflammable and virulent hydrogen sulfide and a preparation method thereof, and belongs to the technical field of hydrogen sulfide adsorption materials. The preparation method comprises the following steps: by taking a carbon nanotube as a matrix, growing iron oxide nanoparticles on the carbon nanotube in situ, so that the dispersion and distribution uniformity of the iron oxide nanoparticles can be improved, and then carrying out Michael addition reaction on a vinyl group on the vinyl modified iron oxide loaded carbon nanotube and a secondary amino group in a hexahydro-s-triazine grafted compound, so as to obtain the composite material. Amine groups containing a large number of hexahydrotriazine groups, piperazine groups and the like can be further cross-linked and coated on the surface of the scavenger, and a hexahydrotriazine-piperazine cross-linked network polymer is formed on the surface of the scavenger; the tubular carbon nanotubes, the ferric oxide particles loaded on the surfaces of the tubular carbon nanotubes and the piperazine-hexahydro-s-triazine cross-linked network-shaped polymer coated on the surface of the hydrogen sulfide scavenger work together, so that the removal effect of hydrogen sulfide in a gas phase and a water phase is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a flammable and toxic hydrogen sulfide safe scavenger and a preparation method thereof, belonging to the technical field of hydrogen sulfide adsorption materials. BACKGROUND

[0002] Under standard conditions, hydrogen sulfide is a colorless, highly irritating gas with a strong odor, and is also corrosive and flammable. It poses a significant threat to human health, the ecological environment, and industrial production, and can cause serious harm even at low concentrations. Numerous studies have shown that sulfides are one of the main causes of air pollution phenomena such as haze and acid rain. Once in the atmospheric environment, hydrogen sulfide is oxidized to generate sulfur oxides such as sulfur dioxide, which in turn corrodes buildings and industrial facilities and poses a threat to human health. The main source of hydrogen sulfide is human industrial activity, particularly in the energy and chemical industries. During the processing of oil and coal, large amounts of sulfides, including hydrogen sulfide, are released. As energy demand increases, the amount of these pollutants being emitted is also rapidly rising. The transport and transformation of sulfides in the atmosphere has led to a number of serious environmental problems, prompting the establishment of more stringent standards for sulfide emissions worldwide. Therefore, controlling hydrogen sulfide emissions in the energy and chemical industries has become a key measure to mitigate these environmental impacts.

[0003] There are many methods for treating hydrogen sulfide, including oxidation, absorption, adsorption, biological methods, electrochemical methods, and electron beam irradiation and microwave decomposition methods. For the removal of hydrogen sulfide on site, there are two main cases: one is the removal of hydrogen sulfide gas that has overflowed or been released into the air from wastewater during mining process, and the other is the removal of hydrogen sulfide from water bodies that release hydrogen sulfide due to changes in the surrounding physical and chemical conditions. The former is referred to as gas hydrogen sulfide removal, and the latter is referred to as water hydrogen sulfide removal.

[0004] Currently, the main hydrogen sulfide scavengers used for gas and water hydrogen sulfide removal are metal oxides such as iron oxide or amine-modified materials. However, iron oxide has poor water solubility and poor solubility, which leads to easy agglomeration in water, resulting in poor removal efficiency. Amine-modified materials often use straight-chain or branched polyamine compounds grafted onto the surface of solid materials. Although modified by amines, when removing hydrogen sulfide in the gas phase, the straight-chain or branched polyamine compounds on the surface of the material are not in an extended state but in a severe agglomeration state, resulting in poor removal efficiency of the material for hydrogen sulfide. For example, in the document "Preparation of Polyethyleneimine Functionalized Multi-walled Carbon Nanotubes and Their Adsorption Performance for Hydrogen Sulfide Gas", polyethyleneimine is grafted onto the surface of carbon nanotubes, and the modified carbon nanotubes have a large number of primary, secondary, and tertiary amine groups on their surface. The absorption efficiency of hydrogen sulfide in water is 0.16 mmol / g, but the removal efficiency of hydrogen sulfide in the gas phase is poor.

[0005] Therefore, it is urgent to develop a hydrogen sulfide safety scavenger which has good scavenging effect on hydrogen sulfide in both gas phase and aqueous phase. SUMMARY

[0006] The present application aims to provide a flammable and toxic hydrogen sulfide safety scavenger and a preparation method thereof, so as to solve the problem that the current polyamine compound modified carbon nanotube has poor hydrogen sulfide scavenging effect.

[0007] The present application provides a preparation method of a flammable and toxic hydrogen sulfide safety scavenger, comprising the following steps:

[0008] (1) acidizing treatment of carbon nanotubes with mixed acid composed of concentrated nitric acid and concentrated sulfuric acid to obtain acid-treated carbon nanotubes;

[0009] (2) mixing the acid-treated carbon nanotubes and polyethylene glycol solution to obtain a dispersion liquid, then heating the dispersion liquid to 80-85℃, adding iron chloride solution under stirring to obtain a precursor liquid, adjusting the pH of the precursor liquid to 9-9.5 with ammonia water, filtering, washing the obtained solid, and drying and heat treating to obtain iron oxide loaded carbon nanotubes;

[0010] (3) modifying the iron oxide loaded carbon nanotubes with divinylsilane coupling agent to obtain vinyl-modified iron oxide loaded carbon nanotubes; the chemical structure of the divinylsilane coupling agent is as follows:

[0011] ;

[0012] (4) Michael addition reaction of the vinyl group in the vinyl-modified iron oxide loaded carbon nanotubes and the secondary amine group in the hexahydro-s-triazine grafting compound to obtain a hydrogen sulfide safety scavenger; the chemical structure of the hexahydro-s-triazine grafting compound is as follows:

[0013] .

[0014] Preferably, the method for acidizing treatment of carbon nanotubes with mixed acid composed of concentrated nitric acid and concentrated sulfuric acid is as follows: adding carbon nanotubes into the mixed acid, heating to 110-120℃, and boiling and refluxing for 4-5h to obtain acid-treated carbon nanotubes.

[0015] Preferably, the volume ratio of the concentrated nitric acid and the concentrated sulfuric acid is 1:3, the mass ratio of the carbon nanotubes and the mixed acid is 1:25-30, the average outer diameter of the carbon nanotubes is 30-50nm, the average inner diameter is 5-10nm, and the average length is 8-12μm.

[0016] Preferably, the mass ratio of the acid-treated carbon nanotubes, the polyethylene glycol solution and the ferric chloride solution is 1:40-50:40-50; the mass fraction of the polyethylene glycol solution is 2-3%, the concentration of the ferric chloride solution is 0.1-0.15 mol / L, and the mass fraction of the ammonia water is 5-8%.

[0017] Preferably, the polyethylene glycol solution is prepared by mixing polyethylene glycol 1000 and water; the temperature of the heat treatment is 450-500℃, and the time of the heat treatment is 2-3 h; and the heat treatment is performed under vacuum.

[0018] Preferably, the divinylsilane coupling agent is prepared by reacting trimethylolpropane diallyl ether and 3-isocyanate propyl trimethoxysilane at a molar ratio of 1:1.

[0019] Preferably, the method for modifying the iron oxide loaded carbon nanotubes by the divinylsilane coupling agent is as follows: the iron oxide loaded carbon nanotubes, the divinylsilane coupling agent and toluene at a mass ratio of 1:0.8-1.2:40-50 are heated to 100-105℃, and mixed and reacted for 18-22 h to obtain the vinyl-modified iron oxide loaded carbon nanotubes.

[0020] Preferably, the method for performing the Michael addition reaction between the vinyl groups in the vinyl-modified iron oxide loaded carbon nanotubes and the secondary amine groups in the hexahydro-s-triazine grafting compound is as follows: the vinyl-modified iron oxide loaded carbon nanotubes, the hexahydro-s-triazine grafting compound, sodium hydroxide and ethanol are heated to 40-45℃, and stirred and reacted for 35-40 h to obtain the hydrogen sulfide safety scavenger.

[0021] Preferably, the mass ratio of the vinyl-modified iron oxide loaded carbon nanotubes, the hexahydro-s-triazine grafting compound, sodium hydroxide and ethanol is 1:1.3-1.5:0.25-0.3:25-28.

[0022] A flammable and toxic hydrogen sulfide safety scavenger prepared by the method for preparing the flammable and toxic hydrogen sulfide safety scavenger as described above.

[0023] Compared with the prior art, the present application has the following advantages: the present application uses carbon nanotubes as a substrate, in-situ grows iron oxide nanoparticles thereon, can improve the dispersion and uniformity of the iron oxide particles, then through the Michael addition reaction of the vinyl groups on the carbon nanotubes and the secondary amine groups in the piperazine-hexahydro-s-triazine grafting compound after the vinyl modification of the iron oxide, can further cross-link and coat the amine-containing groups such as the hexahydro-s-triazine groups and the piperazine groups on the surface of the scavenger, and form a hexahydro-s-triazine-piperazine cross-linked polymer on the surface of the scavenger; the tubular carbon nanotubes, the iron oxide particles loaded on the surface thereof, and the piperazine-hexahydro-s-triazine cross-linked polymer coated on the surface of the hydrogen sulfide scavenger jointly play a role, effectively improving the hydrogen sulfide scavenging effect in the gas phase and the aqueous phase. The tertiary amine nitrogen atom can effectively improve the hydrophilicity of the scavenger, promote the diffusion and migration of hydrogen sulfide in the aqueous phase to the surface of the scavenger, the in-situ grown iron oxide particles are trapped on the surface of the carbon nanotubes and have good dispersion uniformity, can avoid agglomeration in water, and the piperazine-hexahydro-s-triazine cross-linked polymer has a large contact area with hydrogen sulfide in the aqueous phase, so that the hydrogen sulfide scavenger can effectively remove hydrogen sulfide in the aqueous phase. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The nuclear magnetic resonance spectrum of the hexahydro-s-triazine grafting compound prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0025] The following examples are intended to further illustrate the present application, but not to limit the scope of protection of the present application.

[0026] Example 1

[0027] The preparation method of the flammable and toxic hydrogen sulfide safety scavenger of the present embodiment comprises the following steps:

[0028] (1) Put hydroxyethyl hexahydro-s-triazine and dichloromethane with a mass ratio of 1:12 into a reaction kettle, stir uniformly, then cool to 0°C, then add triethylamine, stir uniformly, then add p-toluenesulfonyl chloride, continue to stir for 6 h, filter, remove dichloromethane and excess triethylamine by distillation under reduced pressure, and dry to obtain hexahydro-s-triazine p-toluenesulfonate; wherein the molar ratio of hydroxyethyl hexahydro-s-triazine, triethylamine and p-toluenesulfonyl chloride is 1:3.2:3, and the chemical structure of the hexahydro-s-triazine p-toluenesulfonate is as follows:

[0029] .

[0030] (2) Put hexahydro-s-triazine p-toluenesulfonate, piperazine, sodium bicarbonate, methyl isobutyl ketone, tetrabutyl ammonium bromide and deionized water into a reaction kettle, stir and heat to 80℃, stir for 7h, cool to room temperature, separate, distill the organic phase under reduced pressure, remove the solvent, dry at 60℃ under vacuum for 12h to obtain a hexahydro-s-triazine grafted compound; wherein the molar ratio of hexahydro-s-triazine p-toluenesulfonate, piperazine and sodium bicarbonate is 1:3:3.3, the mass of methyl isobutyl ketone is 2 times the sum of the mass of hexahydro-s-triazine p-toluenesulfonate and piperazine, the mass of tetrabutyl ammonium bromide is 2% of the sum of the mass of hexahydro-s-triazine p-toluenesulfonate and piperazine, the mass of deionized water is 70% of the sum of the mass of hexahydro-s-triazine p-toluenesulfonate and piperazine, and the nuclear magnetic resonance hydrogen spectrum of the hexahydro-s-triazine grafted compound is as shown in Figure 1 , and the chemical structure is as follows:

[0031]

[0032] (3) Put carbon nanotubes into a mixed acid composed of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3, heat to 120℃, reflux for 4h, cool to room temperature, filter, wash the filter cake with deionized water until the washing liquid is neutral, then dry the washed filter cake in an oven at 100℃ to obtain acid-treated carbon nanotubes; wherein the mass ratio of carbon nanotubes to mixed acid is 1:25, the average outer diameter of the carbon nanotubes is 30nm, the average inner diameter is 5nm, and the average length is 8μm.

[0033] (4) Put the acid-treated carbon nanotubes into a polyethylene glycol solution with a mass fraction of 2%, ultrasonically disperse uniformly to obtain a dispersion liquid; then heat the dispersion liquid to 80℃, add a 0.1mol / L ferric chloride solution dropwise into the dispersion liquid under stirring to obtain a precursor liquid, add 5% ammonia water to the precursor liquid to adjust the pH of the precursor liquid to 9, filter, wash the filter cake with deionized water, then dry the filter cake at 120℃ and then heat treat it at 450℃ under vacuum for 2h to obtain iron oxide loaded carbon nanotubes; wherein the mass ratio of acid-treated carbon nanotubes, polyethylene glycol solution and ferric chloride solution is 1:40:40; the polyethylene glycol solution is prepared by stirring and mixing polyethylene glycol 1000 and deionized water.

[0034] (5) Put trimethylolpropane diallyl ether, 3-isocyanate propyl trimethoxysilane and butyl acetate into a reaction kettle, then introduce nitrogen into the reaction kettle, heat to 80℃, stir for 4h, distill under reduced pressure to remove the solvent to obtain a divinyl silane coupling agent; wherein the molar ratio of trimethylolpropane diallyl ether and 3-isocyanate propyl trimethoxysilane is 1:1, the mass of butyl acetate is 2 times the sum of the mass of trimethylolpropane diallyl ether and 3-isocyanate propyl trimethoxysilane, and the chemical structure of the divinyl silane coupling agent is as follows:

[0035] .

[0036] (6) Put the iron oxide loaded carbon nanotubes, divinylsilane coupling agent and toluene with a mass ratio of 1:0.8:40 into a reaction kettle, then introduce nitrogen into the reaction kettle, heat to 100°C, stir for 18 h, cool to room temperature, filter, wash the filter cake with toluene and ethanol in sequence, and dry to obtain the vinyl-modified iron oxide loaded carbon nanotubes.

[0037] (7) Put the vinyl-modified iron oxide loaded carbon nanotubes, hexahydro-piperazine, sodium hydroxide and ethanol with a mass ratio of 1:1.3:0.25:25 into a reaction kettle, then introduce nitrogen into the reaction kettle, heat to 40°C, stir for 35 h, cool to room temperature, filter, wash the filter cake with chloroform, ethanol and deionized water in sequence, and dry to obtain the hydrogen sulfide safety scavenger.

[0038] Example 2

[0039] The preparation method of the flammable and toxic hydrogen sulfide safety scavenger of the present embodiment comprises the following steps:

[0040] (1) Put hydroxyethyl hexahydro-piperazine and dichloromethane with a mass ratio of 1:13 into a reaction kettle, stir uniformly, then cool to 0°C, then add triethylamine, stir uniformly, then add p-toluenesulfonyl chloride, continue to stir for 7 h, filter, remove dichloromethane and excess triethylamine by distillation under reduced pressure, and dry to obtain hexahydro-piperazine p-toluenesulfonate; wherein the molar ratio of hydroxyethyl hexahydro-piperazine, triethylamine and p-toluenesulfonyl chloride is 1:3.4:3, and the chemical structure of hexahydro-piperazine p-toluenesulfonate is as follows:

[0041] .

[0042] (2) Put hexahydro-piperazine p-toluenesulfonate, piperazine, sodium bicarbonate, methyl isobutyl ketone, tetrabutylammonium bromide and deionized water into a reaction kettle, stir and heat to 82°C, stir for 8 h, cool to room temperature, separate the liquid, remove the solvent by distillation under reduced pressure, and dry at 60°C and under vacuum for 12 h to obtain the hexahydro-piperazine grafting compound; wherein the molar ratio of hexahydro-piperazine p-toluenesulfonate, piperazine and sodium bicarbonate is 1:3:3.4, the mass of methyl isobutyl ketone is 3 times the sum of the masses of hexahydro-piperazine p-toluenesulfonate and piperazine, the mass of tetrabutylammonium bromide is 2.5% of the sum of the masses of hexahydro-piperazine p-toluenesulfonate and piperazine, and the mass of deionized water is 75% of the sum of the masses of hexahydro-piperazine p-toluenesulfonate and piperazine, and the chemical structure of the hexahydro-piperazine grafting compound is as follows:

[0043]

[0044] (3) adding carbon nanotubes into mixed acid composed of concentrated nitric acid and concentrated sulfuric acid with a volume ratio of 1:3, heating to 120°C, boiling refluxing for 4h, cooling to room temperature, filtering, washing the filter cake with deionized water until the washing liquid is neutral, and then drying the washed filter cake in an oven at 100°C to obtain acid-treated carbon nanotubes; wherein the mass ratio of carbon nanotubes to mixed acid is 1:28, the average outer diameter of carbon nanotubes is 40 nm, the average inner diameter is 7 nm, and the average length is 9 μm.

[0045] (4) adding acid-treated carbon nanotubes into a polyethylene glycol solution with a mass fraction of 2%, uniformly ultrasonic dispersing to obtain a dispersion liquid; then heating the dispersion liquid to 82°C, adding a ferric chloride solution with a concentration of 0.12 mol / L into the dispersion liquid under stirring to obtain a precursor liquid, adding ammonia water with a mass fraction of 7% into the precursor liquid to adjust the pH of the precursor liquid to 9.5, filtering, washing the filter cake with deionized water, and then drying the filter cake at 120°C and then heat-treating at 480°C under vacuum for 3h to obtain iron oxide loaded carbon nanotubes; wherein the mass ratio of acid-treated carbon nanotubes, polyethylene glycol solution and ferric chloride solution is 1:45:50; the polyethylene glycol solution is prepared by stirring and mixing polyethylene glycol 1000 and deionized water.

[0046] (5) adding trimethylolpropane diallyl ether, 3-isocyanate propyl trimethoxysilane and butyl acetate into a reaction kettle, then introducing nitrogen into the reaction kettle, heating to 82°C, stirring for 5h, and removing the solvent by reduced pressure distillation to obtain a divinyl silane coupling agent; wherein the molar ratio of trimethylolpropane diallyl ether to 3-isocyanate propyl trimethoxysilane is 1:1, the mass of butyl acetate is 2 times the sum of the masses of trimethylolpropane diallyl ether and 3-isocyanate propyl trimethoxysilane, and the chemical structure of the divinyl silane coupling agent is as follows:

[0047] .

[0048] (6) adding iron oxide loaded carbon nanotubes, divinyl silane coupling agent and toluene with a mass ratio of 1:1:45 into a reaction kettle, then introducing nitrogen into the reaction kettle, heating to 102°C, stirring for 20h, cooling to room temperature, filtering, washing the filter cake with toluene and ethanol in sequence respectively, and drying to obtain vinyl-modified iron oxide loaded carbon nanotubes.

[0049] (7) Add vinyl-modified iron oxide supported carbon nanotubes, hexahydrotriazine grafted compound, sodium hydroxide and ethanol in a mass ratio of 1:1.4:0.28:27 to a reaction vessel, then introduce nitrogen gas into the reaction vessel, heat to 42°C, stir and react for 38 h, cool to room temperature, filter, wash the filter cake with chloroform, ethanol and deionized water in sequence, and dry to obtain hydrogen sulfide safe remover.

[0050] Example 3

[0051] The preparation method of the flammable and highly toxic hydrogen sulfide safety scavenger in this embodiment includes the following steps:

[0052] (1) Hydroxyethyl hexahydrotriazine and dichloromethane in a mass ratio of 1:15 were added to a reaction vessel, stirred until homogeneous, and then cooled to 0°C. Triethylamine was then added, stirred until homogeneous, and then p-toluenesulfonyl chloride was added. The reaction was continued for 8 hours. The mixture was filtered, and the filtrate was distilled under reduced pressure to remove dichloromethane and excess triethylamine. After drying, hexahydrotriazine p-toluenesulfonate was obtained. The molar ratio of hydroxyethyl hexahydrotriazine, triethylamine, and p-toluenesulfonyl chloride was 1:3.5:3. The chemical structure of hexahydrotriazine p-toluenesulfonate is as follows:

[0053] .

[0054] (2) Hexahydrotriazine p-toluenesulfonate, piperazine, sodium bicarbonate, methyl isobutyl ketone, tetrabutylammonium bromide and deionized water were added to a reaction vessel, stirred and heated to 85°C, stirred for 9 h, cooled to room temperature, separated, and the organic phase was distilled under reduced pressure to remove the solvent. It was then dried at 60°C under vacuum for 12 h to obtain the hexahydrotriazine graft compound. The molar ratio of hexahydrotriazine p-toluenesulfonate, piperazine and sodium bicarbonate was 1:3:3.5, the mass of methyl isobutyl ketone was 3 times the sum of the masses of hexahydrotriazine p-toluenesulfonate and piperazine, the mass of tetrabutylammonium bromide was 3% of the sum of the masses of hexahydrotriazine p-toluenesulfonate and piperazine, and the mass of deionized water was 80% of the sum of the masses of hexahydrotriazine p-toluenesulfonate and piperazine. The chemical structure of the hexahydrotriazine graft compound is as follows:

[0055]

[0056] (3) Carbon nanotubes were added to a mixed acid consisting of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3, heated to 120°C, boiled and refluxed for 4 hours, cooled to room temperature, filtered, and the filter cake was washed with deionized water until the washing liquid was neutral. The washed filter cake was then dried in an oven at 100°C to obtain acid-treated carbon nanotubes. The mass ratio of carbon nanotubes to the mixed acid was 1:30, the average outer diameter of the carbon nanotubes was 50 nm, the average inner diameter was 10 nm, and the average length was 12 μm. The mixed acid consisting of concentrated nitric acid and concentrated sulfuric acid has stronger oxidizing properties. When carbon nanotubes are oxidized, the ports of the carbon nanotubes can be opened. The carbon atoms at the ports of the carbon nanotubes have high activity and are easily oxidized. After oxidation treatment, more oxygen-containing functional groups can be introduced onto the carbon nanotubes, improving the dispersion uniformity of carbon nanotubes in water, and thus improving the loading uniformity of iron oxide particles on the carbon nanotubes.

[0057] (4) Add acid-treated carbon nanotubes to a 3% polyethylene glycol solution and ultrasonically disperse them to obtain a dispersion. Then heat the dispersion to 85°C and add a 0.15 mol / L ferric chloride solution dropwise to the dispersion under stirring to obtain a precursor solution. Add 8% ammonia water to the precursor solution to adjust the pH of the precursor solution to 9.5. Filter the solution and wash the filter cake with deionized water. Then dry the filter cake at 120°C and heat-treat it at 500°C and under vacuum for 3 hours to obtain iron oxide-loaded carbon nanotubes. The mass ratio of acid-treated carbon nanotubes, polyethylene glycol solution and ferric chloride solution is 1:50:50. The polyethylene glycol solution is prepared by stirring and mixing polyethylene glycol 1000 and deionized water.

[0058] (5) Trimethylolpropane diallyl ether, 3-isocyanate-propyltrimethoxysilane and butyl acetate were added to a reaction vessel, and nitrogen gas was introduced into the reaction vessel. The mixture was heated to 85°C and stirred for 5 hours. The solvent was removed by vacuum distillation to obtain a divinylsilane coupling agent. The molar ratio of trimethylolpropane diallyl ether and 3-isocyanate-propyltrimethoxysilane was 1:1, and the mass of butyl acetate was 3 times the sum of the masses of trimethylolpropane diallyl ether and 3-isocyanate-propyltrimethoxysilane. The chemical structure of the divinylsilane coupling agent is as follows:

[0059] .

[0060] (6) Add iron oxide-supported carbon nanotubes, divinylsilane coupling agent and toluene in a mass ratio of 1:1.2:50 to the reaction vessel, then introduce nitrogen into the reaction vessel, heat to 105°C, stir and react for 22 h, cool to room temperature, filter, wash the filter cake with toluene and ethanol respectively, and dry to obtain vinyl-modified iron oxide-supported carbon nanotubes.

[0061] (7) Add vinyl-modified iron oxide supported carbon nanotubes, hexahydrotriazine grafted compound, sodium hydroxide and ethanol in a mass ratio of 1:1.5:0.3:28 to a reaction vessel, then introduce nitrogen into the reaction vessel, heat to 45°C, stir and react for 40 h, cool to room temperature, filter, wash the filter cake with chloroform, ethanol and deionized water in sequence, and dry to obtain hydrogen sulfide safe remover.

[0062] Comparative Example 1

[0063] The difference between the preparation method of the flammable and highly toxic hydrogen sulfide safe remover in this comparative example and the preparation method of the flammable and highly toxic hydrogen sulfide safe remover in Example 1 is that in step (2) of the preparation method of the flammable and highly toxic hydrogen sulfide safe remover in this comparative example, piperazine is replaced with N1,N4-dimethyl-1,4-cyclohexanediamine. The chemical structure of the hexahydrotriazine grafted compound prepared is as follows:

[0064] .

[0065] Comparative Example 2

[0066] The difference between the preparation method of the flammable and highly toxic hydrogen sulfide safe remover in this comparative example and the preparation method of the flammable and highly toxic hydrogen sulfide safe remover in Example 1 is that in step (2) of the preparation method of the flammable and highly toxic hydrogen sulfide safe remover in this comparative example, piperazine is replaced with N,N'-dimethyl-1,6-hexanediamine. The chemical structure of the hexahydrotriazine grafted compound prepared is as follows:

[0067] .

[0068] Comparative Example 3

[0069] The difference between the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in this comparative example and the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in Example 1 is that step (4) is omitted in the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in this comparative example, and the iron oxide-loaded carbon nanotubes in step (6) are replaced with the acid-treated carbon nanotubes obtained in step (3).

[0070] Comparative Example 4

[0071] The difference between the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in this comparative example and the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in Example 1 is that steps (1) to (2) and steps (5) to (7) are omitted in the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in this comparative example. That is, the flammable and highly toxic hydrogen sulfide safety remover prepared in this comparative example is the iron oxide supported carbon nanotube prepared in step (4) of Example 1.

[0072] Comparative Example 5

[0073] The difference between the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in this comparative example and the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in Example 1 is that steps (1) to (2) and step (7) are omitted in the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in this comparative example. That is, the flammable and highly toxic hydrogen sulfide safety remover prepared in this comparative example is the vinyl-modified iron oxide supported carbon nanotube prepared in step (6) of Example 1.

[0074] Comparative Example 6

[0075] The difference between the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in this comparative example and the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in Example 1 is that in step (4) of the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in this comparative example, the polyethylene glycol solution is replaced with a polyvinyl alcohol solution. The polyvinyl alcohol solution is prepared by stirring and mixing polyvinyl alcohol and deionized water. The weight average molecular weight of polyvinyl alcohol is 80,000 and the degree of alcoholysis is 85%.

[0076] Comparative Example 7

[0077] The difference between the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in this comparative example and the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in Example 1 is that in step (6) of the preparation method of the flammable and highly toxic hydrogen sulfide safety remover in this comparative example, the divinylsilane coupling agent is replaced with allyltrimethoxysilane.

[0078] Experimental Example 1

[0079] To evaluate the removal efficiency of the hydrogen sulfide safe scavengers prepared in each embodiment and comparative example for hydrogen sulfide removal from the gas phase, a fixed-bed reactor was used to evaluate the desulfurization performance of the hydrogen sulfide safe scavengers. Air and hydrogen sulfide were mixed to prepare a solution with a hydrogen sulfide concentration of 2500 mg / m³. 3 The test gas was then introduced into the inlet of a transparent glass tube containing a hydrogen sulfide safety scavenger at a space velocity of 2000 h / h under ambient temperature and pressure. Simultaneously, the concentration of hydrogen sulfide in the exhaust gas was measured at the outlet of the transparent glass tube. The exhaust gas was then treated with alkaline solution recovery. The test gas was considered complete when the hydrogen sulfide concentration at the outlet of the transparent glass tube reached 25 mg / m³. 3 When the threshold is reached, it is considered to have penetrated. The penetration time is recorded and the penetration sulfur capacity is calculated. The results are shown in Table 1. The conditions for testing the desulfurization performance of different hydrogen sulfide safe scavengers are the same.

[0080] Table 1. Breakthrough time and breakthrough sulfur capacity of hydrogen sulfide safe scavengers for hydrogen sulfide removal in the gas phase.

[0081] Hydrogen sulfide safe scavenger Penetration time (min) Penetration sulfur capacity (mg / g) Example 1 1650 429 Example 2 1638 421 Example 3 1654 433 Comparative Example 1 550 141 Comparative Example 2 541 139 Comparative Example 3 485 124 Comparative Example 4 469 107 Comparative Example 5 476 116 Comparative Example 6 611 159 Comparative Example 7 563 143

[0082] As shown in Table 1, the hydrogen sulfide safe remover prepared in this invention uses carbon nanotubes as a matrix, on which iron oxide nanoparticles are grown in situ, which can improve the uniformity of the dispersion of iron oxide particles. Furthermore, through the Michael addition reaction between the vinyl groups on the carbon nanotubes loaded with vinyl-modified iron oxide and the secondary amine groups in the hexahydrotriazine grafted compound, a large number of amine groups such as hexahydrotriazine groups and piperazine groups can be cross-linked and coated on the surface of the remover, thereby effectively improving the removal effect of hydrogen sulfide.

[0083] As shown in Example 1 and Comparative Examples 1-2, when the piperazine group in the hexahydrotriazine graft compound is replaced with cyclohexanediamine or hexanediamine, the hydrogen sulfide removal effect of the hydrogen sulfide safe scavenger on hydrogen sulfide deteriorates. This indicates that the structure of the hexahydrotriazine graft compound has a significant impact on the removal effect of hydrogen sulfide. The possible reasons are as follows: Compared with cyclohexanediamine or hexanediamine, the piperazine group in the hexahydrotriazine graft compound has greater rigidity. When it undergoes a crosslinking reaction with the vinyl groups on vinyl-modified iron oxide-supported carbon nanotubes, the resulting crosslinked network polymer has better rigidity and stability. A structurally stable crosslinked network polymer is more conducive to improving the removal effect of hydrogen sulfide.

[0084] As can be seen from Example 1 and Comparative Examples 3-5, when steps (4) and (7) are omitted, that is, when the in-situ growth and loading of iron oxide and the chemical grafting of hexahydrotriazine grafted compound on the surface of iron oxide are omitted, the adsorption and removal effect of the prepared scavenger on hydrogen sulfide becomes worse, which proves that the iron oxide loaded in the scavenger and the hexahydrotriazine grafted compound on the surface of iron oxide both help to improve the removal of hydrogen sulfide.

[0085] As shown in Example 1 and Comparative Example 6, when iron oxide is grown in situ on the surface of acid-treated carbon nanotubes, the scavenger prepared using polyethylene glycol as a dispersant has a better adsorption and removal effect on hydrogen sulfide. The possible reasons are as follows: Since both carbon nanotubes and iron oxide particles are inorganic particles, they are bonded together through electrostatic interactions and weak intermolecular forces. When polyethylene glycol 1000 is used as a dispersant, its smaller molecular weight and better solubility can better promote the uniform loading of iron oxide particles on carbon nanotubes, improve the loading uniformity of iron oxide particles and their binding force with carbon nanotubes, and thus improve the chemical crosslinking uniformity and density of hexahydrotriazine grafted compounds on vinyl-modified iron oxide-loaded carbon nanotubes, forming a more uniform crosslinked network polymer of hexahydrotriazine grafted compounds, thereby improving the removal effect of hydrogen sulfide.

[0086] As can be seen from Example 1 and Comparative Example 7, when the divinylsilane coupling agent is replaced with allyltrimethoxysilane, the adsorption and removal effect of the scavenger on hydrogen sulfide deteriorates. The possible reasons are as follows: When allyltrimethoxysilane is used, the density of vinyl groups grafted onto the vinyl-modified iron oxide-supported carbon nanotubes decreases. When the vinyl-modified iron oxide-supported carbon nanotubes and the hexahydrotriazine grafted compound undergo a chemical crosslinking reaction, the density, uniformity, and binding strength of the crosslinked network polymer formed by the hexahydrotriazine grafted compound are all reduced, resulting in a deterioration in the removal effect of the scavenger on hydrogen sulfide.

[0087] Experimental Example 2

[0088] To evaluate the removal effect of the hydrogen sulfide safe scavengers prepared in each embodiment and comparative example on hydrogen sulfide in the aqueous phase, a certain concentration of hydrogen sulfide aqueous solution was prepared in a closed glove box. Then, the hydrogen sulfide safe scavenger was added to the hydrogen sulfide aqueous solution, dispersed evenly, and allowed to stand. The hydrogen sulfide content in the aqueous solution was tested at regular intervals. When the hydrogen sulfide content in the aqueous solution no longer decreased, it indicated that the hydrogen sulfide safe scavenger had reached saturation in removing hydrogen sulfide. Based on the initial concentration of hydrogen sulfide in the hydrogen sulfide aqueous solution and the concentration when saturation was achieved, the mass of hydrogen sulfide removed by each unit mass of hydrogen sulfide safe scavenger was calculated, and the sulfur capacity of the hydrogen sulfide safe scavenger was obtained. At the same time, based on the concentration of hydrogen sulfide in the hydrogen sulfide aqueous solution at the 15th minute of the experiment, the average removal rate of hydrogen sulfide in the aqueous solution by the hydrogen sulfide safe scavenger in the first 15 minutes was calculated. The results are shown in Table 2.

[0089] Table 2. Sulfur capacity and average removal rate of hydrogen sulfide from aqueous phase by safe hydrogen sulfide scavengers.

[0090] Hydrogen sulfide safe scavenger Sulfur capacity (mg / g) Average scavenging rate (mg / g min) Example 1 11.9 0.0923 Example 2 12.1 0.0947 Example 3 11.6 0.0914 Comparative Example 1 3.7 0.0161 Comparative Example 2 3.9 0.0165 Comparative Example 3 3.1 0.0144 Comparative Example 4 2.9 0.0139 Comparative Example 5 2.6 0.0125 Comparative Example 6 4.1 0.0171 Comparative Example 7 3.8 0.0163

[0091] As shown in Table 2, the hydrogen sulfide safe remover prepared in this invention also has a good removal effect on hydrogen sulfide in the aqueous phase. Its principle may be similar to that of hydrogen sulfide removal in the gas phase, as follows: the tubular carbon nanotubes and the iron oxide particles loaded on their surface, as well as the piperazine-hexahydrotriazine cross-linked network polymer coated on the surface of the hydrogen sulfide remover, work together. The tertiary amine nitrogen atoms can effectively improve the hydrophilicity of the remover and promote the diffusion and migration of hydrogen sulfide in the aqueous phase to the surface of the remover. The in-situ grown iron oxide particles are trapped on the surface of the carbon nanotubes and have good dispersion uniformity, which can avoid agglomeration in water. The piperazine-hexahydrotriazine cross-linked network polymer has a large contact area with hydrogen sulfide in the aqueous phase, so that the hydrogen sulfide safe remover can effectively remove hydrogen sulfide in the aqueous phase.

[0092] In Comparative Examples 1-2, the use of cyclohexanediamine or hexamethylenediamine may have resulted in decreased compatibility between the scavenger and the aqueous system due to the enhanced hydrophobicity of the cross-linked network polymer, leading to a poorer removal effect of hydrogen sulfide. Comparative Examples 3-5 lacked the in-situ growth and loading steps of iron oxide and the chemical grafting step of the hexahydrotriazine graft compound onto the iron oxide surface, resulting in a poorer adsorption and removal effect of the scavenger on hydrogen sulfide. In Comparative Example 6, the poor uniformity of the loading of iron oxide particles on the carbon nanotubes may have led to a poor removal effect of hydrogen sulfide from the water. In Comparative Example 7, the low density and uniformity of the piperazine-hexahydrotriazine cross-linked network polymer may have resulted in a poor removal effect of hydrogen sulfide from the water.

Claims

1. A method for preparing a flammable and highly toxic hydrogen sulfide safe scavenger, characterized in that, Includes the following steps: (1) Carbon nanotubes are acidified by a mixed acid consisting of concentrated nitric acid and concentrated sulfuric acid to obtain acid-treated carbon nanotubes; (2) Mix the acid-treated carbon nanotubes and polyethylene glycol solution to obtain a dispersion. Heat the dispersion to 80-85°C and add ferric chloride solution under stirring to obtain a precursor solution. Adjust the pH of the precursor solution to 9-9.5 with ammonia water, filter, wash the filtered solid, dry and heat treat it to obtain iron oxide-loaded carbon nanotubes. (3) Iron oxide-supported carbon nanotubes were modified with a divinylsilane coupling agent to obtain vinyl-modified iron oxide-supported carbon nanotubes; the chemical structure of the divinylsilane coupling agent is as follows: ； (4) A Michael addition reaction was carried out on the vinyl groups in the vinyl-modified iron oxide-supported carbon nanotubes and the secondary amine groups in the hexahydrotriazine graft compound to obtain a hydrogen sulfide safe scavenger; the chemical structure of the hexahydrotriazine graft compound is as follows: 。 2. The preparation method of the flammable and highly toxic hydrogen sulfide safe scavenger as described in claim 1, characterized in that, The method for acidifying carbon nanotubes using a mixed acid composed of concentrated nitric acid and concentrated sulfuric acid is as follows: add carbon nanotubes to the mixed acid, heat to 110~120℃, and boil under reflux for 4~5 hours to obtain acid-treated carbon nanotubes.

3. The preparation method of the flammable and highly toxic hydrogen sulfide safety scavenger as described in claim 2, characterized in that, The volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:3, the mass ratio of carbon nanotubes to mixed acid is 1:25~30, the average outer diameter of the carbon nanotubes is 30~50nm, the average inner diameter is 5~10nm, and the average length is 8~12μm.

4. The preparation method of the flammable and highly toxic hydrogen sulfide safety scavenger as described in claim 1, characterized in that, The mass ratio of the acid-treated carbon nanotubes, polyethylene glycol solution, and ferric chloride solution is 1:40~50:40~50; the mass fraction of the polyethylene glycol solution is 2~3%, the concentration of the ferric chloride solution is 0.1~0.15mol / L, and the mass fraction of the ammonia solution is 5~8%.

5. The preparation method of the flammable and highly toxic hydrogen sulfide safety scavenger as described in claim 4, characterized in that, The polyethylene glycol solution is prepared by mixing polyethylene glycol 1000 and water; the heat treatment temperature is 450~500℃, the time is 2~3h, and the heat treatment is carried out under vacuum conditions.

6. The preparation method of the flammable and highly toxic hydrogen sulfide safety scavenger as described in claim 1, characterized in that, The divinylsilane coupling agent is prepared by reacting trimethylolpropane diallyl ether and 3-isocyanate propyltrimethoxysilane in a molar ratio of 1:

1.

7. The method for preparing the flammable and highly toxic hydrogen sulfide safety scavenger as described in claim 1 or 6, characterized in that, The method for modifying iron oxide-supported carbon nanotubes with a divinylsilane coupling agent is as follows: iron oxide-supported carbon nanotubes, divinylsilane coupling agent and toluene in a mass ratio of 1:0.8~1.2:40~50 are heated to 100~105℃ and mixed and reacted for 18~22h to obtain vinyl-modified iron oxide-supported carbon nanotubes.

8. The preparation method of the flammable and highly toxic hydrogen sulfide safety scavenger as described in claim 1, characterized in that, The method for Michael addition reaction of vinyl groups in vinyl-modified iron oxide supported carbon nanotubes and secondary amine groups in hexahydrotriazine grafted compounds is as follows: vinyl-modified iron oxide supported carbon nanotubes, hexahydrotriazine grafted compounds, sodium hydroxide and ethanol are heated to 40~45℃ and stirred for 35~40h to obtain a hydrogen sulfide safe scavenger.

9. The preparation method of the flammable and highly toxic hydrogen sulfide safety scavenger as described in claim 8, characterized in that, The mass ratio of the vinyl-modified iron oxide-supported carbon nanotubes, hexahydrotriazine grafted compound, sodium hydroxide, and ethanol is 1:1.3~1.5:0.25~0.3:25~28.

10. A flammable and highly toxic hydrogen sulfide safe remover prepared by the method described in any one of claims 1-9.

Images