A composite micro-electrolytic iron-carbon slow-release material and its preparation method and application

Abstract

The present invention discloses a composite micro-electrolytic iron-carbon slow-release material and its preparation method and application. The composite micro-electrolytic iron-carbon slow-release material comprises a first metal, a second metal, silicon dioxide, and a carrier precursor; the first metal is coated with silicon dioxide on its outer surface, and the first metal coated with silicon dioxide is distributed in the pores of the carrier precursor and / or on its surface. The preparation method comprises (1) preparing a carrier precursor; (2) preparing a first silicon-containing material stream; (3) preparing a second iron-containing material stream; (4) preparing a third material stream by combining the second material stream with an organic polymer; (5) treating the third material stream with the carrier precursor, and then drying and calcining to obtain the iron-carbon slow-release material. The iron-carbon slow-release material provided by the present invention can achieve a slow reaction between iron and carbon to avoid rapid oxidation of iron, and combined with the in-situ catalytic oxidation method, it can achieve long-term remediation of petroleum hydrocarbon pollutants.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic materials, and in particular relates to a catalytic material for catalytic oxidation and a preparation method thereof. Background Art

[0002] In recent years, with the increasing emission of refractory organic pollutants and their difficult biodegradation characteristics, advanced oxidation technologies (AOPs) have attracted the attention of researchers. Advanced oxidation technologies can use strong oxidizing free radical species produced by oxidants such as ozone, hydrogen peroxide, persulfate and percarbonate under the activation of catalysts to efficiently oxidize and degrade organic pollutants. They have the advantages of high oxidation potential, fast reaction rate and almost no selectivity for organic matter.

[0003] Conventional iron-carbon reaction is an effective means of degrading organic pollutants. It can produce micro-electrolysis reactions inside the system and has been applied in many sewage treatment fields. However, conventional iron-carbon reaction has violent reactions, produces a large amount of iron sludge, is easily passivated and loses activity, and blocks the reaction channel. In addition, the reaction generally needs to be carried out under acidic conditions, which greatly limits its application.

[0004] Combining the iron-carbon system with persulfate oxidant has broadened the pH application range, but there are still problems such as violent reaction and large amount of iron sludge. Researchers have tried to use slow-release technology to solve this problem.

[0005] After the slow-release technology has received widespread attention, it has gradually been applied in the field of soil and groundwater pollution treatment, and has achieved good remediation effects. However, most of the current research is on the slow-release of oxidants, and there are fewer studies on the slow-release of iron. Some researchers use iron carriers such as nano zero-valent iron and porous Fe2O3 particles to activate persulfate, control the activation rate of persulfate, and ensure that the system continuously and efficiently degrades pollutants. However, the problem of iron consumption caused by electrolysis in the iron-carbon system and the generation of a large amount of iron sludge has not been solved. The generation of iron sludge will block the water flow channel, and it is difficult to replace the catalyst, so iron slow-release materials are needed to make the catalytic material have long-lasting activity.

[0006] CN103550252A discloses a method for preparing an iron sustained-release agent and the prepared iron sustained-release agent, wherein a method for preparing an iron sustained-release agent comprises: adding a quaternary ammonium salt cationic surfactant to a mixed system of ethanol and water, adding an auxiliary template, ammonia water and tetraethyl orthosilicate to the system to obtain a colloidal mixed system; sealing the colloidal mixed system at room temperature for 2 to 5 days, filtering to obtain a silicon-based mesoporous molecular sieve precursor, washing, drying and calcining the silicon-based mesoporous molecular sieve precursor to obtain a silicon-based mesoporous molecular sieve; adding the silicon-based mesoporous molecular sieve to a supersaturated solution containing divalent iron ions, ultrasonically treating to obtain an iron sustained-release agent. The invention improves the efficiency and effect of the diffusion of iron ions from the liquid phase to the solid phase by adopting ultrasonic-assisted dispersion technology, and reduces the iron release rate. However, the invention does not involve the existence and influence of the iron-carbon micro-electrolysis reaction.

[0007] CN108675431A discloses a method for preparing a porous carbon-coated magnetic nano-iron water treatment composite material by low-temperature pyrolysis of a metal organic framework (MOF) and its application method in water treatment. The present invention first uses urea to prepare graphite phase carbon nitride (g-C3N4), then couples it with an iron-containing MOF in situ, and finally pyrolyzes it at low temperature in an inert atmosphere to obtain a porous carbon-coated magnetic nano-iron water treatment composite material. The iron element in the composite material obtained by the present invention is mainly present in the porous carbon in the form of zero-valent iron and γ-Fe2O3, has excellent magnetic properties, and is easy to be magnetically separated. However, the product prepared by this method has close contact between iron and carbon, which is easy to cause the loss of iron ions and is not suitable for iron-carbon advanced oxidation reactions.

[0008] CN109647874A discloses the preparation and application of functional slow-release microcapsules for heavy metal treatment in soil, which discloses that under certain conditions, microcrystalline cellulose is used as raw material, sodium alginate is used as adhesive, CaCl2 is used as curing liquid, and nano zero-valent iron (nZVI) is used as core material to prepare slow-release microcapsules for heavy metal pollution treatment in soil. The invention uses slow-release agents to encapsulate nano zero-valent iron, and the reaction rate is difficult to control.

[0009] CN112374596A discloses a moldable nano zero-valent iron slow-release agent, a preparation method thereof, and its application in in-situ remediation of groundwater and soil heavy metal pollution. The nano zero-valent iron slow-release agent is composed of raw materials in percentage by mass: 20% to 40% paraffin, 10% to 40% quartz sand, 15% to 50% polyethylene glycol, 5% to 15% activated carbon, and 1% to 5% nano zero-valent iron. The preparation method comprises: heating the paraffin and maintaining it in a molten state, then adding quartz sand, polyethylene glycol, activated carbon and nano zero-valent iron, stirring and mixing evenly, pouring the paste mixture into a mold and cooling and molding, and obtaining the nano zero-valent iron slow-release agent. The invention uses the unique effect of paraffin to form a slow-release effect, which will have a certain impact on the reaction treatment effect. Summary of the invention

[0010] The main purpose of the present invention is to provide a composite micro-electrolytic iron-carbon slow-release material and its preparation method and application. The provided iron-carbon slow-release material can achieve a slow reaction between iron and carbon to avoid rapid oxidation of iron, and combined with an in-situ catalytic oxidation method, can achieve long-term remediation of petroleum hydrocarbon pollutants.

[0011] The first aspect of the present invention provides a composite micro-electrolytic iron-carbon slow-release material, which includes a first metal, a second metal, silicon dioxide, and a carrier precursor; the first metal is dispersed particles of elemental iron and ferric oxide, and the second metal is at least one of copper, silver, tin, and lead; the first metal is coated with silicon dioxide on the surface, and the first metal coated with silicon dioxide is distributed in the pores of the carrier precursor and / or on its surface; the carrier precursor includes a composite carrier composed of a second metal, carbon, and an inorganic refractory oxide.

[0012] Furthermore, in the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, based on the total weight of the composite micro-electrolytic iron-carbon sustained-release material, the first metal content is 5wt%~35wt%, preferably 10wt%~25wt%; the second metal content is 0.5wt%~6.0wt%, preferably 2.0wt%~5.0wt%; the silicon dioxide content is 0.5wt%~4.0wt%, preferably 1.0wt%~3.0wt%; the carbon content is 10wt%~55wt%, preferably 15wt%~40wt%; the inorganic refractory oxide content is 20wt%~60wt%, preferably 25wt%~50wt%.

[0013] Furthermore, in the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, the pore size distribution of the composite micro-electrolytic iron-carbon sustained-release material is as follows, wherein the pore diameter of the first-level channel is less than 4nm, and the most probable pore diameter is 2.5nm; the pore diameter of the second-level channel is 4-9nm, and the most probable pore diameter is 7.4nm; the pore diameter of the third-level channel is greater than 9nm, preferably 9-20nm, and the most probable pore diameter is 13.6nm; further, the ratio of the peak intensity (peak height) represented by the Y-axis coordinates of the most probable pore diameters of the first-level channel, the second-level channel and the third-level channel is 1.0:0.5-2.0:0.5-3.0.

[0014] Furthermore, in the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, the specific surface area of ​​the composite micro-electrolytic iron-carbon sustained-release material is 120 to 1000 m 2 / g.

[0015] The second aspect of the present invention provides a method for preparing a composite micro-electrolytic iron-carbon sustained-release material, comprising the following steps:

[0016] (1) mixing an inorganic refractory oxide, a carbon precursor, a second metal and a binder, and further forming, drying and calcining to obtain a carrier precursor;

[0017] (2) in the presence of an organic solvent, uniformly mixing a first silicon precursor and a second silicon precursor to obtain a first material flow;

[0018] (3) mixing the iron-containing compound with the stabilizer under contact conditions, and then introducing an alkaline substance to react to obtain a second stream;

[0019] (4) mixing the first material flow, the second material flow, and the organic polymer to obtain a third material flow after mixing them uniformly;

[0020] (5) The third material stream obtained in step (4) is mixed with the carrier precursor obtained in step (1) for treatment, and then dried and calcined to obtain an iron-carbon slow-release material.

[0021] Furthermore, in the preparation method of the composite micro-electrolytic iron-carbon slow-release material, the inorganic refractory oxide in step (1) can be one or more of alumina, molecular sieve, and clay; further, the molecular sieve can be one or more of ZSM-5 molecular sieve, A-type molecular sieve, Y-type molecular sieve, and β molecular sieve; the clay can be silica-alumina clay with a particle size of 300 to 2000 mesh, the sum of the mass of SiO2 and Al2O3 in the component accounts for more than 80% of the total mass of the silica-alumina clay, and the specific surface area is 5 to 500 m 2 / g.

[0022] Furthermore, in the preparation method of the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, the carbon precursor in step (1) can be one or more selected from biomass charcoal, petroleum-based charcoal, coal-based charcoal, etc., and the carbon element content of the carbon source is not less than 60wt%; further, the carbon precursor can specifically be one or more of activated carbon, fruit shell powder, wood powder, coconut shell powder, coal powder, coal tar, asphalt, organic polymer (the organic polymer can be at least one of polyethylene, polystyrene, polyvinyl chloride, polyacrylic acid, polyacrylonitrile, polymethyl methacrylate, polylactic acid, polycarbonate, phenolic resin, urea-formaldehyde resin), cellulose.

[0023] Furthermore, in the method for preparing the composite micro-electrolytic iron-carbon sustained-release material, the second metal in step (1) is at least one of copper, silver, tin and lead.

[0024] Furthermore, in the preparation method of the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, the binder in step (1) is one or more of water, an inorganic binder and an organic binder, the inorganic binder can be selected from one or more of silica sol, aluminum sol, aluminum dihydrogen phosphate, and water glass, and the organic binder can be selected from one or more of hydroxymethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, hydroxypropyl methyl cellulose, polyvinyl alcohol, and polyethylene glycol.

[0025] Furthermore, in the method for preparing the composite micro-electrolytic iron-carbon sustained-release material, the drying temperature in step (1) is 50 to 120°C, preferably 60 to 110°C.

[0026] Furthermore, in the preparation method of the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, the calcination in step (1) is carried out under anaerobic conditions, such as in an inert atmosphere such as nitrogen, helium, neon, argon, etc., and the calcination temperature is 500-900°C, preferably 600-700°C; the calcination time is 1-8h, preferably 2-4h.

[0027] Furthermore, in the preparation method of the above-mentioned composite micro-electrolytic iron-carbon slow-release material, the first silicon source in step (2) is at least one of silica sol, sodium silicate, and silicic acid, preferably silica sol; the silica sol is further preferably alkaline silica sol, the pH value of the alkaline silica sol is 9-12, and the concentration of the silica sol is 10wt% to 40wt%.

[0028] Furthermore, in the preparation method of the composite micro-electrolytic iron-carbon sustained-release material, the second silicon source in step (2) is an organic silicon ester and / or an organic siloxane, and the second silicon source can be selected from one or more of tetraethyl silicate, methyl orthosilicate, methyl trimethoxysilane, methyl triethoxysilane, trimethyl chlorosilane, and octyl trimethoxysilane; preferably tetraethyl silicate. The mass ratio of the second silicon source to the first silicon source is 1:2 to 6 based on the silicon dioxide contained.

[0029] Furthermore, in the preparation method of the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, the organic solvent in step (2) is an alcohol compound and / or an ether compound, and the alcohol compound can be selected from one or more of methanol, ethanol, n-propanol, n-butanol, n-pentanol, isopropanol, isobutanol and isopentanol, preferably ethanol; the ether compound can be specifically selected from one or more of diethyl ether, petroleum ether, tetrahydrofuran, 1,4-dioxane, preferably tetrahydrofuran.

[0030] Furthermore, in the preparation method of the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, the iron-containing compound in step (3) is an iron salt, and the iron salt includes a trivalent iron salt and an optional divalent iron salt, preferably a trivalent iron salt; the trivalent iron salt is at least one of ferric nitrate, ferric chloride, ferric citrate, ferric acetate, and ferric sulfate, preferably ferric sulfate; the divalent iron salt is at least one of ferrous chloride, ferrous acetate, and ferrous sulfate, preferably ferrous sulfate.

[0031] Furthermore, in the preparation method of the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, the stabilizer in step (3) is one or more of hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, polyamide, polyethyleneimine, and dimercaptosuccinic acid.

[0032] Furthermore, in the preparation method of the composite micro-electrolytic iron-carbon sustained-release material, the alkaline substance in step (1) is at least one of sodium hydroxide, potassium hydroxide, ammonia water, urea, and sodium bicarbonate. The molar amount of the alkaline substance added is 0.8 to 1.5 times that of the iron element.

[0033] Furthermore, in the preparation method of the above-mentioned catalytic oxidation catalytic material, the organic polymer in step (4) is a soluble organic polymer, which can be specifically selected from one or more of polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyethylene oxide, polymethacrylic acid, polystyrene sulfonic acid, and polydimethoxystyrene; the amount of organic polymer added is 0.5% to 10% of the total mass of the third stream. The polyvinyl pyrrolidone can be any one of PVP-K12, PVP-K15, PVP-K30, PVP-K60, and PVP-K90; the polyvinyl alcohol can be any one of PVA-1788, PVA-1792, and PVA-1799; the polyethylene glycol can be any one of PEG2000, PEG4000, PEG6000, PEG8000, PEG10000, and PEG20000.

[0034] Furthermore, in the method for preparing the composite micro-electrolytic iron-carbon sustained-release material, the treatment temperature in step (5) is generally controlled to be between 20 and 90°C, preferably between 40 and 80°C.

[0035] Furthermore, in the preparation method of the composite micro-electrolytic iron-carbon sustained-release material, the drying in step (5) is carried out under anaerobic conditions, such as in an inert atmosphere such as nitrogen, helium, neon, argon, etc., and the drying temperature is 80 to 120° C., preferably 90 to 110° C.; the drying time is 2 to 8 hours, preferably 3 to 4 hours. The drying can be achieved by any of the existing drying equipment.

[0036] Furthermore, in the preparation method of the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, the calcination in step (5) is carried out under anaerobic conditions, such as in an inert atmosphere such as nitrogen, helium, neon, argon, etc., and the calcination temperature is 300-700°C, preferably 500-600°C; the calcination time is 2-8h, preferably 3-4h.

[0037] The third aspect of the present invention provides a composite micro-electrolytic iron-carbon slow-release material obtained by the above-mentioned preparation method, the iron-carbon slow-release material comprising a first metal, a second metal, silica, and a carrier precursor; the first metal is dispersed particles of elemental iron and ferric oxide, and the second metal is at least one of copper, silver, tin, and lead; the first metal is coated with silica on the surface, and the first metal coated with silica is distributed in the pores of the carrier precursor and / or on its surface; the carrier precursor comprises a composite carrier composed of a second metal, carbon, and an inorganic refractory oxide.

[0038] Furthermore, in the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, based on the total weight of the composite micro-electrolytic iron-carbon sustained-release material, the first metal content is 5wt%~35wt%, preferably 10wt%~25wt%; the second metal content is 0.5wt%~6.0wt%, preferably 2.0wt%~5.0wt%; the silicon dioxide content is 0.5wt%~4.0wt%, preferably 1.0wt%~3.0wt%; the carbon content is 10wt%~55wt%, preferably 15wt%~40wt%; the inorganic refractory oxide content is 20wt%~60wt%, preferably 25wt%~50wt%.

[0039] Furthermore, in the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, the pore size distribution of the composite micro-electrolytic iron-carbon sustained-release material is as follows, wherein the pore diameter of the first-level channel is less than 4nm, and the most probable pore diameter is 2.5nm; the pore diameter of the second-level channel is 4-9nm, and the most probable pore diameter is 7.4nm; the pore diameter of the third-level channel is greater than 9nm, preferably 9-20nm, and the most probable pore diameter is 13.6nm; further, the peak intensity ratio represented by the most probable pore diameters of the first-level channel, the second-level channel and the third-level channel corresponding to the Y-axis coordinate is 1.0:0.5-2.0:0.5-3.0.

[0040] Furthermore, in the above-mentioned composite micro-electrolytic iron-carbon sustained-release material, the specific surface area of ​​the composite micro-electrolytic iron-carbon sustained-release material is 120 to 1000 m 2 / g.

[0041] A fourth aspect of the present invention provides an application of the above-mentioned composite micro-electrolysis iron-carbon slow-release material in the treatment of wastewater containing petroleum hydrocarbons.

[0042] Furthermore, in the above application, the specific application process is that the petroleum hydrocarbon-containing wastewater is contacted with an oxidant and reacts in the presence of the above iron-carbon slow-release material to obtain purified water after the reaction.

[0043] Furthermore, in the above application, the oxidant is one or more of ozone, hydrogen peroxide, sodium persulfate, and sodium percarbonate, preferably sodium persulfate.

[0044] Furthermore, in the above application, the petroleum hydrocarbons contained in the petroleum hydrocarbon-containing wastewater are mainly C4-C40 hydrocarbons, and the hydrocarbons generally include but are not limited to one or more of alkanes, olefins, benzene series, halogenated hydrocarbons, etc.

[0045] Compared with the prior art, the composite micro-electrolytic iron-carbon sustained-release material and its preparation method and application described in the present invention have the following advantages:

[0046] The present invention provides a composite catalyst formed by silica-coated iron particles and carrier materials such as activated carbon. Among them, iron and silica are pre-mixed and cross-linked together to prepare a hydrophobic silica porous structure to constrain the iron particles, so that the reaction of the iron particles is controllable and iron mud is not easy to be generated. During use, the reaction core iron is constantly consumed, but its highly dispersed distribution in the carrier can enable the carrier to continue to maintain structural integrity, the material is not easy to collapse, and continues to play an adsorption role on pollutant components in subsequent treatments. Furthermore, copper, silver and other metals with higher potentials are introduced into the catalytic material, which can form a micro-electrolysis reaction with iron. A multi-dimensional micro-electrolysis reaction network is constructed by different potential differences, which can more efficiently convert and degrade pollutants and is applicable to a wider range of treatments. The catalyst can be used in combination with an oxidant in an advanced oxidation manner, has a wider range of pH applications, and has a wider range of application value.

[0047] At the same time, the carbon-containing composite material used as a carrier has a strong adsorption capacity for organic pollutant components, and can adsorb pollutant molecules to the catalyst surface, thereby increasing the probability of contact between active components and pollutant molecules, improving local concentration, and promoting the initial reaction rate, which is beneficial to the catalytic oxidation reaction. The content of activated carbon in the carbon-containing composite carrier is controlled at a reasonable ratio, and the unique contact mode with iron particles also significantly reduces the ineffective reaction of iron-carbon micro-electrolysis. The carbon-containing composite carrier has a porous structure and can also adsorb iron ions produced by the iron-carbon reaction, forming catalytic active centers in situ, and continuously maintaining good catalytic oxidation activity. DETAILED DESCRIPTION

[0048] The preparation method of the present invention is further described below in conjunction with specific examples, but the scope of the present invention is not limited to the scope of these examples.

[0049] The specific surface area and average pore size described in the embodiment are measured by a nitrogen physical adsorption instrument. The ratio of the most probable pore size corresponding to the Y-axis value on the pore size distribution curve is recorded as the peak intensity ratio. The iron ion analysis method is microwave digestion / inductively coupled plasma mass spectrometry. The silica content involved in the present invention is the mass of silica combined with iron when added, excluding the mass of silica introduced in the inorganic refractory oxide and the binder.

[0050] Example 1

[0051] 135g activated carbon, 70g silica-alumina clay, 8g copper powder and 13g water glass were mixed evenly, extruded into strips according to the conventional method, dried at 110℃ for 8h, and calcined at 680℃ for 5h in the absence of oxygen to obtain a carrier precursor. Weigh 200g of ferric sulfate to make 100ml of iron salt solution, add 1.5g of octadecyltrimethylammonium bromide, stir evenly, and then add 30.5g of ammonia water to form colloidal solution A. Weigh 6.7g of 30wt% silica sol, 2.8g of tetraethyl silicate and 20g of ethanol, mix evenly, add 6g of polyvinyl pyrrolidone (K90) while stirring to form solution B. Mix solutions A and B, stir for 30min, add the carrier precursor, let stand at room temperature (25℃) for 6h, dry at 100℃, and then calcine the dried material at 550℃ for 3h in the absence of oxygen to obtain catalyst A1. The specific surface area of ​​the catalytic material is 612m 2 / g, the ratio of the most probable pore peak intensity of the first-order pore, the second-order pore and the third-order pore is 1:0.7:1.4.

[0052] Example 2

[0053] 28g activated carbon, 52g silica-alumina clay, 24g ZSM-5 molecular sieve, 5g nano silver powder and 10g aluminum dihydrogen phosphate colloid were mixed evenly, extruded into strips according to the conventional method, dried at 100℃ for 12h, and calcined at 800℃ for 2h in an oxygen-free state to obtain a carrier precursor. Weigh 76g ferrous sulfate to make 50ml iron salt solution, add 0.7g polyamide and stir evenly. Then add 20g sodium hydroxide to form colloidal solution A. Weigh 2.6g sodium silicate, 2.0g methyltriethoxysilane and 20g ether, mix evenly, and add 1.8g polyethylene glycol with an average molecular weight of about 8000 while stirring to form solution B. Mix solutions A and B, stir for 30min, add the carrier, heat to 50℃ in a water bath, react for 6h, take out the carrier and dry at 90℃, and calcine the dried material at 500℃ for 2h in an oxygen-free state to obtain catalyst A2. The specific surface area of ​​the catalytic material is 352m 2 / g, the ratio of the most probable pore peak intensity of the first-order pore, the second-order pore and the third-order pore is 1:1.2:1.6.

[0054] Example 3

[0055] 30.0g activated carbon, 23.8g alumina, 4.9g lead powder and 3.0g carboxymethyl cellulose were mixed evenly, extruded into strips according to the conventional method, dried at 90℃ for 7h, and calcined at 620℃ under argon protection for 6h to obtain a carrier precursor. Weigh 96g of ferric acetate to make 70ml of iron salt solution, add 1.2g of hexadecyltrimethylammonium bromide, and stir evenly. Then add 42g of sodium bicarbonate to form colloidal solution A. Weigh 2.5g of 40% alkaline silica sol, 1.4g of tetraethyl silicate and 20g of methanol, mix evenly, and add 6g of polyvinyl alcohol with an average degree of polymerization of 1750 while stirring to form solution B. Mix solutions A and B, stir for 5min, add the carrier precursor, add a water bath to 60℃ and let stand for 5h, dry at 110℃, and calcine the dried material at 600℃ in an oxygen-free environment for 5h to obtain catalyst A3. The specific surface area of ​​the catalytic material is 461m 2 / g, the ratio of the most probable pore peak intensity of the first-order pore, the second-order pore and the third-order pore is 1:1.3:2.2.

[0056] Example 4

[0057] Weigh 63g of ferrous chloride and 82g of ferric chloride to make 150ml of iron salt solution, add 1.0g of polyacetimide and stir evenly. Add 30g of urea to form colloidal solution A. Weigh 2.2g of silicic acid, 0.7g of trimethylchlorosilane and 14g of tetrahydrofuran, mix evenly, and add 2.8g of polyacrylic acid with a molecular weight of about 8500 while stirring to form solution B. Mix 100g of activated carbon, 105g of white carbon black, 12g of lead powder and 18.2g of water glass evenly, extrude into strips according to the conventional method, dry at 80℃ for 12h, and calcine at 650℃ under helium protection for 6h to obtain a carrier precursor. Mix solutions A and B, stir for 15min, add the carrier precursor, let stand at room temperature for 12h, dry at 100℃, and calcine the dried material at 620℃ under nitrogen protection for 6h to obtain catalyst A4. The specific surface area of ​​the catalytic material is 579m 2 / g, the ratio of the most probable pore peak intensity of the first-order pore, the second-order pore and the third-order pore is 1:1.1:2.4.

[0058] Example 5

[0059] Weigh 123g of ferric citrate to make 85ml of iron salt solution, add 1.3g of hexadecyltrimethylammonium chloride, and stir evenly. Then add 21g of ammonia water to form colloidal solution A. Weigh 9.7g of 20% alkaline silica sol, 1.2g of tetraethyl silicate and 20g of ethanol, mix evenly, and add 1.9g of 100K polyoxyethylene while stirring to form solution B. Mix 28.0g of activated carbon, 38.8g of silica-alumina clay, 4.0g of tin powder and 6.6g of hydroxypropyl methylcellulose evenly, extrude into strips according to conventional methods, dry at 90℃ for 12h, and calcine at 600℃ for 5h under nitrogen protection to obtain a carrier precursor. Mix solutions A and B, stir for 20min, add the carrier precursor, add a water bath to 45℃ and let stand for 7h, take out the carrier and dry at 105℃, and calcine the dried material at 560℃ for 5h under nitrogen protection to obtain catalyst A5. The specific surface area of ​​the catalytic material is 311m 2 / g, the ratio of the most probable pore peak intensity of the first-order pore, the second-order pore and the third-order pore is 1:1.8:2.8.

[0060] Example 6

[0061] 200 mL of catalyst A1 was loaded into a cylindrical reaction tube. The gasoline simulated petroleum hydrocarbon wastewater with a COD of 150 mg / L was continuously treated with a sodium persulfate dosage of 250 mg / L. The iron ion concentration in the effluent was 66 mg / L, and the COD removal rate was 93.1%.

[0062] Example 7

[0063] 1g of catalyst A2 was measured and filled into a sealed bottle. 100g of gasoline-simulated petroleum hydrocarbon wastewater with an initial COD of 150 mg / L was poured into it. Then 0.2g of sodium persulfate was added. The mixture was continuously oscillated at 25°C in a constant temperature oscillator for 180min. The iron ion concentration in the water sample after the reaction was detected to be 55mg / L, and the COD removal rate was 95.3%.

[0064] Example 8

[0065] 200 mL of catalyst A3 was loaded into a cylindrical reaction tube and continuously reacted to treat diesel simulated petroleum hydrocarbon wastewater with a COD of 120 mg / L under the action of 125 mg / L of sodium persulfate. The iron ion concentration in the effluent was 41 mg / L and the COD removal rate was 92.5%.

[0066] Example 9

[0067] 0.5g of catalyst A4 was measured and filled into a sealed bottle, and 100g of gasoline-simulated petroleum hydrocarbon wastewater with an initial COD of 100 mg / L was poured into it. Then 0.2g of sodium persulfate was added and the mixture was continuously oscillated at 35°C in a constant temperature oscillator for 120min. The iron ion concentration in the water sample after the reaction was detected to be 38mg / L, and the COD removal rate was 94.2%.

[0068] Example 10

[0069] 500mL of catalyst A5 was loaded into a cylindrical reaction tube. The gasoline simulated petroleum hydrocarbon wastewater with a COD of 120 mg / L was continuously treated with a sodium persulfate dosage of 300 mg / L. The iron ion concentration in the effluent was 59 mg / L, and the COD removal rate was 96.1%.

[0070] Comparative Example 1

[0071] 193g activated carbon, 70g silica-alumina clay and 15g water glass were mixed evenly, extruded into strips according to conventional methods, dried at 110°C for 8h, and calcined at 600°C in an oxygen-free state for 6h to obtain a carrier precursor. 44g ferric acetate was weighed to prepare an iron salt solution, and the carrier precursor was added to the solution for impregnation, and then rotary evaporated to dryness. The dried material was calcined at 550°C in an oxygen-free state for 3h to obtain catalyst B1.

[0072] Comparative Example 2

[0073] Weigh 45g of iron filings and activated carbon respectively, mix and load them in a cylindrical reaction tube, and use conventional iron-carbon reaction to treat gasoline simulated petroleum hydrocarbon wastewater with a COD of 200 mg / L. There is obvious yellow precipitation in the effluent, and the contact between iron filings and activated carbon quickly hardens. The iron ion concentration is 7526 mg / L, and the COD removal rate after iron ion precipitation is 86.8%.

[0074] Comparative Example 3

[0075] Example 8 was repeated, except that catalyst A3 was replaced by catalyst B1. The iron ion concentration in the effluent was 1297 mg / L, and the COD removal rate was 81.2%.

[0076] Comparative Example 4

[0077] Using conventional iron-carbon reaction, 30g, 50g and 45g of activated carbon, inert porcelain balls and iron filings were weighed respectively, mixed evenly and filled into a cylindrical reaction tube. Toluene with a COD of 160 mg / L was introduced to simulate petroleum hydrocarbon wastewater. There was obvious yellow precipitation in the effluent, and the contact between the iron filings and the activated carbon quickly hardened. The iron ion concentration was 6621 mg / L, and the COD removal rate was 81.5% after the iron ions were precipitated.

[0078] Comparative Example 5

[0079] Weigh 60g of iron filings and 40g of activated carbon, mix and load them in a cylindrical reaction tube, use gasoline with a COD average of 200mg / L to simulate petroleum hydrocarbon wastewater, add 100 mg / L of sodium persulfate for continuous reaction, and there is obvious yellow precipitation in the effluent water. The contact between the iron filings and the activated carbon quickly hardens. The iron ion concentration is 7983 mg / L, and the COD removal rate after the iron ions are precipitated is 91.2%.

Claims

1. A composite micro-electrolysis iron-carbon slow-release material, the iron-carbon slow-release material comprising a first metal, a second metal, silicon dioxide, and a carrier precursor; the first metal is dispersed particles of elemental iron and ferric oxide, and the second metal is at least one of copper, silver, tin, and lead; the first metal is coated with silicon dioxide on the surface, and the first metal coated with silicon dioxide is distributed in the pores of the carrier precursor and / or on its surface; the carrier precursor comprises a composite carrier composed of the second metal, carbon, and an inorganic refractory oxide; in, The preparation method of the composite micro-electrolytic iron-carbon sustained-release material comprises the following steps: (1) An inorganic refractory oxide, a carbon precursor, a second metal and a binder are mixed, and further formed, dried and calcined to obtain a carrier precursor; the inorganic refractory oxide is one or more of alumina, molecular sieve and clay; (2) In the presence of an organic solvent, a first silicon precursor and a second silicon precursor are uniformly mixed to obtain a first material flow; the first silicon precursor is at least one of silica sol, sodium silicate, and silicic acid, and the second silicon precursor is an organic silicon ester and / or an organic siloxane; (3) mixing the iron-containing compound with the stabilizer under contact conditions, and then introducing an alkaline substance to react to obtain a second stream; (4) mixing the first material flow, the second material flow and the organic polymer, and mixing them evenly to obtain a third material flow; the organic polymer is a soluble organic polymer, selected from one or more of polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyethylene oxide, polymethacrylic acid, polystyrene sulfonic acid and polydimethoxystyrene; (5) The third material stream obtained in step (4) is mixed with the carrier precursor obtained in step (1) for treatment, and then dried and calcined to obtain an iron-carbon slow-release material.

2. The composite micro-electrolytic iron-carbon sustained-release material according to claim 1, characterized in that: Based on the total weight of the composite micro-electrolytic iron-carbon sustained-release material, the first metal content is 5wt% to 35wt%, the second metal content is 0.5wt% to 6.0wt%, the silicon dioxide content is 0.5wt% to 4.0wt%, the carbon content is 10wt% to 55wt%, and the inorganic refractory oxide content is 20wt% to 60wt%.

3. The composite micro-electrolytic iron-carbon sustained-release material according to claim 1, characterized in that: Based on the total weight of the composite micro-electrolytic iron-carbon sustained-release material, the first metal content is 10wt% to 25wt%, the second metal content is 2.0wt% to 5.0wt%, the silicon dioxide content is 1.0wt% to 3.0wt%, the carbon content is 15wt% to 40wt%, and the inorganic refractory oxide content is 25wt% to 50wt%.

4. The composite micro-electrolytic iron-carbon sustained-release material according to claim 1, characterized in that: The pore size distribution of the composite micro-electrolytic iron-carbon sustained-release material is as follows: the pore diameter of the first-order channel is less than 4nm, and the most probable pore diameter is 2.5nm; the pore diameter of the second-order channel is 4-9nm, and the most probable pore diameter is 7.4nm; the pore diameter of the third-order channel is 9-20nm, and the most probable pore diameter is 13.6nm, and the peak intensity ratio represented by the Y-axis coordinates of the most probable pore diameters of the first-order channel, the second-order channel and the third-order channel is 1.0: 0.5-2.0: 0.5-3.

0.

5. The composite micro-electrolytic iron-carbon sustained-release material according to claim 1, characterized in that: The specific surface area of ​​the composite micro-electrolytic iron-carbon sustained-release material is 120-1000m 2 / g.

6. A method for preparing a composite micro-electrolytic iron-carbon sustained-release material, comprising the following steps: (1) An inorganic refractory oxide, a carbon precursor, a second metal and a binder are mixed, and further formed, dried and calcined to obtain a carrier precursor, wherein the second metal is at least one of copper, silver, tin and lead; and the inorganic refractory oxide is one or more of alumina, molecular sieve and clay; (2) In the presence of an organic solvent, a first silicon precursor and a second silicon precursor are uniformly mixed to obtain a first material flow; the first silicon precursor is at least one of silica sol, sodium silicate, and silicic acid, and the second silicon precursor is an organic silicon ester and / or an organic siloxane; (3) mixing the iron-containing compound with the stabilizer under contact conditions, and then introducing an alkaline substance to react to obtain a second stream; (4) mixing the first material flow, the second material flow and the organic polymer, and mixing them evenly to obtain a third material flow; the organic polymer is a soluble organic polymer, selected from one or more of polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyethylene oxide, polymethacrylic acid, polystyrene sulfonic acid and polydimethoxystyrene; (5) The third material stream obtained in step (4) is mixed with the carrier precursor obtained in step (1) for treatment, and then dried and calcined to obtain an iron-carbon slow-release material.

7. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: In step (1), the carbon precursor is selected from one or more of biomass carbon, petroleum-based carbon, and coal-based carbon, and the carbon content of the carbon source is not less than 60wt%.

8. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: In step (1), the carbon precursor is one or more of activated carbon, fruit shell powder, wood powder, coconut shell powder, coal powder, coal tar, asphalt, organic polymer, and cellulose.

9. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: The binder in step (1) is one or more of water, an inorganic binder and an organic binder, the inorganic binder is selected from one or more of silica sol, alumina sol, aluminum dihydrogen phosphate and water glass, and the organic binder is selected from one or more of hydroxymethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, hydroxypropyl methyl cellulose, polyvinyl alcohol and polyethylene glycol.

10. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: The drying temperature in step (1) is 50-120°C.

11. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: The drying temperature in step (1) is 60-110°C.

12. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: The calcination in step (1) is carried out under oxygen-free conditions at a calcination temperature of 500 to 900°C.

13. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: The calcination in step (1) is carried out in an inert atmosphere of nitrogen, helium, neon or argon at a temperature of 600 to 700°C.

14. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: The silica sol in step (2) is alkaline silica sol, the pH value of the alkaline silica sol is 9-12, and the concentration of the silica sol is 10wt%-40wt%.

15. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: In step (2), the second silicon precursor is selected from one or more of tetraethyl silicate, methyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, trimethylchlorosilane, and octyltrimethoxysilane.

16. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: The second silicon precursor in step (2) is tetraethyl silicate.

17. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: In step (2), the organic solvent is an alcohol compound and / or an ether compound.

18. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: The iron-containing compound in step (3) is an iron salt, which includes a ferric salt and an optional ferrous salt; the ferric salt is at least one of ferric nitrate, ferric chloride, ferric citrate, ferric acetate, and ferrous sulfate, and the ferrous salt is at least one of ferrous chloride, ferrous acetate, and ferrous sulfate.

19. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 18, characterized in that: The ferric salt is ferrous sulfate; the ferrous salt is ferrous sulfate.

20. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: In step (3), the stabilizer is one or more of hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, polyamide, polyethyleneimine, and dimercaptosuccinic acid.

21. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: In step (1), the alkaline substance is at least one of sodium hydroxide, potassium hydroxide, ammonia water, urea, and sodium bicarbonate, and the molar amount of the alkaline substance added is 0.8 to 1.5 times that of the iron element.

22. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: In step (4), the amount of organic polymer added is 0.5% to 10% of the total mass of the third material stream.

23. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: The treatment temperature in step (5) is 20 to 90°C.

24. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: The treatment temperature in step (5) is 40 to 80°C.

25. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: In step (5), the drying is carried out under anaerobic conditions, the drying temperature is 80 to 120° C., and the drying time is 2 to 8 hours.

26. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: In step (5), the drying is carried out under anaerobic conditions, the drying temperature is 90 to 110° C., and the drying time is 3 to 4 hours.

27. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: In step (5), the calcination is carried out under oxygen-free conditions, the calcination temperature is 300 to 700° C., and the calcination time is 2 to 8 hours.

28. The method for preparing the composite micro-electrolytic iron-carbon sustained-release material according to claim 6, characterized in that: In step (5), the calcination is carried out under nitrogen, helium, neon or argon at a temperature of 500 to 600° C. and for a time of 3 to 4 hours.

29. Use of a composite micro-electrolytic iron-carbon slow-release material obtained by the preparation method described in any one of claims 1 to 5 and claims 6 to 28 in the treatment of wastewater containing petroleum hydrocarbons.

30. The use according to claim 29, characterized in that: The application process is that wastewater containing petroleum hydrocarbons is contacted with an oxidant and reacts in the presence of an iron-carbon slow-release material, and purified water is obtained after the reaction.

31. The use according to claim 30, characterized in that: The oxidant is one or more of ozone, hydrogen peroxide, sodium persulfate and sodium percarbonate.

32. The use according to claim 29, characterized in that: The petroleum hydrocarbons contained in the petroleum hydrocarbon-containing wastewater are C4-C40 hydrocarbons, and the hydrocarbons are one or more of alkanes, olefins, benzene series, and halogenated hydrocarbons.