A titanium dioxide-based photocatalytic foam ceramic for targeted degradation of emerging pollutants, its preparation method and application

Abstract

This application discloses a TiO2-based photocatalytic foam ceramic for targeted degradation of emerging pollutants, its preparation method, and its application. The method includes: uniformly dispersing organic additives and pH adjusters in deionized water to form a homogeneous solution; then adding titanium dioxide powder, sintering aids, defect control agents, and photocatalytically active components in batches, uniformly dispersing them to form a suspension slurry; adding fiber and / or whisker reinforcing phases to form a composite slurry; impregnating organic foam in the composite slurry, followed by desizing and drying to form a composite; subjecting the composite to gradient-heating heat treatment to remove organic matter, forming a green body; and finally sintering to obtain the finished product. This method, based on the electronic characteristics and molecular structure of the target pollutants, matches and constructs a specific heterojunction system to achieve highly efficient targeted degradation of emerging pollutants such as antibiotics, perfluorinated compounds, and phenols. The resulting ceramic product possesses high structural strength, high photocatalytic activity, and excellent environmental stability.

Claims

1. A method for preparing TiO2-based photocatalytic foam ceramics for targeted degradation of emerging pollutants, characterized in that, Includes the following steps: Step S1: Preparation of titanium dioxide-based composite slurry Organic additives and pH adjusters are added to deionized water and dispersed evenly to form a homogeneous solution; TiO2 powder, photocatalytic active components, sintering aids, and defect control agents are added to the homogeneous solution in batches and uniformly dispersed to form a titanium dioxide-based suspension slurry; fiber and / or whisker reinforcing phases are added to the suspension slurry and uniformly dispersed to form a titanium dioxide-based composite slurry; Step S2: Preparation of titanium dioxide-based foam ceramic wet blank The organic foam is completely immersed in the titanium dioxide-based composite slurry obtained in step S1 for impregnation treatment; after impregnation, the organic foam is removed and excess slurry on the surface is removed by squeezing or centrifugation; then drying is performed; the above impregnation-deslurry-drying cycle is repeated several times to allow the titanium dioxide-based composite slurry to accumulate layer by layer on the surface of the organic foam skeleton to obtain a titanium dioxide-based foam ceramic wet blank. Step S3: Preparation of titanium dioxide-based foam ceramic preform The titanium dioxide-based foam ceramic green body obtained in step S2 is first air-dried to remove surface free moisture; then it is dried by programmed temperature rise to further remove internal moisture; then the dried green body is subjected to debinding heat treatment by gradient temperature rise to fully remove organic foam and organic additives by thermal debonding, while titanium dioxide particles, photocatalytic active components, sintering aids, defect control agents and reinforcing phases are initially sintered together to form a titanium dioxide-based foam ceramic green body with a three-dimensional interconnected pore structure. Step S4: Sintering and Heterogeneous Structure Construction The green body obtained in step S3 is subjected to controlled sintering heat treatment, wherein sintering aids promote the fusion of titanium dioxide and photocatalytic active components to form a ceramic framework network, and defect control agents inhibit grain growth through solid solution doping; during sintering, the reinforcing phase and the ceramic framework form an interface bond through solid-phase diffusion, and construct a heterojunction interface or generate a new photocatalytic active phase through band matching, ultimately obtaining a TiO2-based photocatalytic foam ceramic with a three-dimensional framework composed of continuous photocatalytic functional phases, possessing both mechanical strength and targeted degradation of emerging pollutants.

2. The preparation method according to claim 1, characterized in that, In step S1, the TiO2 powder is selected from any one or a combination of anatase TiO2, rutile TiO2, commercial P25 TiO2 or modified powder thereof, and its average particle size is 10nm-50μm. The TiO2 modified powder is TiO2 powder obtained by any of the following modification methods: (1) Cation doping, wherein the cation is selected from Li + Na + K + 、Rb + Cs + Mg² + Ca² + Sr² + Ba² + Al³ + Ga³ + In³ + Sn 4+ Sb³ + Sb 5+ Bi³ + ,Sc³ + Ti 4+ V³ + V 4+ V 5+ Cr³ + Cr 4+ Mn² + Mn³ + Mn 4+ Fe² + Fe³ + Co² + Co³ + Ni² + Ni³ + Cu² + Zn² + Y³ + Zr 4+ 、Nb 5+ Mo 6+ Ru 4+ 、Rh³ + Pd² + Ag + La³ + Ce³ + Ce 4+ Pr³ + Pr 4+ 、Nd³ + Sm³ + Eu³ + Gd³ + Tb³ + 、Tb 4+ Dy³ + Ho³ + Er³ + Tm³ + Yb³ + Lu³ + Hf 4+ Ta 5+ W 6+ Re 4 + Re 6+ Os 4+ Ir 4+ Pt² + Pt 4+ and Au³ + Any one or more of the following, with a doping concentration of 0.1-15 at% (2) Anion doping, wherein the anion is selected from any one or more of B, C, N, F, P, S, Cl, Br and I, and the doping concentration is 0.5-10 at% (3) Oxygen vacancy regulation, with an oxygen vacancy concentration of 10 18 -10 21 cm -3 ; (4) Defect engineering modification, dislocation / grain boundary density 10 14 -10 16 cm -2 ; The modified powder still possesses semiconductor properties, with a band gap ranging from 1.5 to 5.5 eV; The photocatalytic active component is an inorganic oxide powder with semiconductor properties, having a band gap range of 1.5-5.5 eV, and is selected from at least one component from the following I)- V); I) Single metal oxides The general chemical formula is M m O n M is a single metallic element, m = 1-3, n = 1-5; including one or more of ZnO, WO3, Bi2O3, Fe2O3, Cu2O, V2O5, MoO3, SnO2, MnO2, ZrO2, Ga2O3, Nb2O5, Ta2O5, In2O3, GeO2, RuO2, IrO2, Co3O4, NiO, Mn3O4, CuO, Ag2O, CoO, MnO, SnO, Sb2O3, Fe3O4, and Au2O and their modified derivatives; II) Composite metal oxides Composed of two or more metal cations, and further subdivided according to crystal structure as: a) Perovskites and their derived phases: general formula ABO3 or A (n+1) B n O (3n+1) , where n is an integer from 1 to 3, A is selected from at least one of La, Bi, Ba, Sr, Ca, Pb, Na and K, and B is selected from at least one of Ti, Zr, Hf, Nb, Ta, W, Mo, V, Cr, Mn, Fe, Co, Ni, Al, Ga and Sn; b) Spinel-type oxides: with the general formula AB₂O₄, wherein A is selected from at least one of Mg, Zn, Ni, Co, Cu, Fe, Mn and Li, and B is selected from at least one of Al, Ga, Cr, Fe, Mn, Co and Ti; c) Layered oxyacid salts having a layered crystal structure with an interlayer spacing of 0.5 nm to 1.5 nm, selected from at least one of the following: c1) Layered titanates, with the general formula A2Ti3O7 or ATi2O5, wherein A is selected from H, Li, Na, K, Rb or Cs; C2) Protonated layered niobates or tantalates, with the general formula HNb3O8 or HTa2O6; C3) Aurivillius phase bismuth-based oxides, selected from Bi2WO6, Bi2MoO6, and Bi4Ti3O 12 At least one of them; c4) Layered nickelates, with the general formula ANiO2, wherein A is selected from Li or Na; d) Other functional oxoacid salts, selected from at least one of the following groups: d1) Scheelite-type oxides, with the general formula AWO4, AMoO4 or AVO4, wherein A is selected from Bi, Ca, Sr, Zn or Pb; d2) Perovskite-type rare earth ferrates, with the general formula LnFeO3, wherein Ln is selected from La, Pr, Nd or Sm; d3) Pyrochlore-type oxides, with the general formula Ln2B2O7, wherein Ln is selected from La, Gd, Sm or Nd, and B is selected from Ti, Zr or Sn; d4) Tungsten bronze type oxide, with the general formula M x TO3, where T is selected from W, Nb, or Ta, M is selected from Na or K, and 0.1 ≤ x ≤ 1.0; d5) Olivine-type oxides, with the general formula M2SiO4 or M2GeO4, wherein M is selected from Mg, Zn, Fe or Mn; d6) Inverse spinel-type stannate Zn2SnO4; d7) Copper-iron ore type oxides, with the general formula CuMO2, wherein M is selected from Fe, Al, Ga or Cr; III) Rare earth-based oxides a) Single rare earth oxide Ln a O x , where Ln is La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Sc, a = 1–2, x = 1.5–3; b) Rare earth composite oxides: including perovskite-type LaMO3, NdMO3, ScMO3, YMO3, PrMO3, SmMO3, EuMO3, GdMO3, TbMO3, DyMO3, HoMO3, ErMO3, TmMO3, YbMO3, and LuMO3, where M is selected from transition metals Fe, Co, Sc, Ti, V, Cr, Mn, Ni, Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, and W. Re, Os, Ir, Pt, Au, or Hg; pyrochlore-type Gd₂Ti₂O₇, Y₂Zr₂O₇, Sc₂Ti₂O₇, La₂Ti₂O₇, Ce₂Ti₂O₇, Pr₂Ti₂O₇, Nd₂Ti₂O₇, Sm₂Ti₂O₇, Eu₂Ti₂O₇, Tb₂Ti₂O₇, Dy₂Ti₂O₇, Ho₂Ti₂O₇, Er₂Ti₂O₇, Tm₂Ti₂O₇, Yb₂Ti₂O₇, Lu₂Ti₂O₇; bismuth rare earth co-doped oxides Bi. 1-x Ln x VO4, wherein Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc, Y, x = 0.1-0.5, and at least one of the layered rare earth oxides La2O2CO3, Pr4O7, Ce2O2CO3, Nd2O2CO3, Sm2O2CO3, Eu2O2CO3, Gd2O2CO3, Tb2O2CO3, Dy2O2CO3, Ho2O2CO3, Er2O2CO3, Tm2O2CO3, Yb2O2CO3, Lu2O2CO3, Sc2O2CO3, Y2O2CO3; the interlayer spacing of the layered rare earth oxide structure is 0.8-1.2 nm; IV) Frontier structural metal oxides a) High-entropy oxides: general formula is (M1, M2, ... M n ) a O M1, M2, ..., Mn are at least five different metallic elements, each independently selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mg, Al, Li, Zr, Nb, Mo, Sn, Hf, Ta, W, or Ce, with each metallic element accounting for 5% to 35% of the total metallic elements, and the configuration entropy ΔS of the high-entropy oxide is... mix ≥ 1.5R, where R is the ideal gas constant 8.314 J·mol - ¹·K - ¹; (b) A two-dimensional nano-metal oxide, wherein the matrix material of the two-dimensional nano-metal oxide is selected from at least one of MnO2, MoO3, V2O5, Co3O4, Fe2O3, SnO2, ZnO and Nb2O5, has a plate-like or layered morphology, has a thickness of 0.5 nm to 10 nm, has a lateral dimension to thickness ratio ≥ 50, and the two-dimensional nano-metal oxide has preferentially exposed crystal planes, wherein the crystal planes are selected from at least one of the {001}, {010}, {100} and {110} plane families; c) MOF-derived porous oxides, wherein the MOF-derived porous oxides are obtained by heat treatment conversion of metal-organic framework precursors, wherein the metal center of the precursor is selected from at least one of Zn, Co, Fe, Cu, Zr, Ti, Ni and Al, and the resulting oxides retain the morphological characteristics and pore structure of the precursors, with a specific surface area ≥ 50 m² / g, pore volume ≥ 0.1 cm³ / g, and pore size distribution spanning from micropores to mesopores, ranging from 0.5 nm to 50 nm; V) Precursor compound: is the water-insoluble oxalate and / or carbonate corresponding to the metal oxides in I)-II), wherein the precursor compound decomposes in situ during sintering heat treatment to generate the corresponding photocatalytically active oxide; Wherein, "insoluble in water" means: solubility in deionized water at 25°C ≤ 0.1 g / 100 mL; the precursor compound must meet the following requirements: decomposition temperature between 200-1200°C, residual carbon content after decomposition < 0.1 wt.%, and no introduction of impurity anions harmful to photocatalytic activity; VI) The photocatalytic active component described in any of I) to IV) above is modified using one or more of the following methods, and the resulting powder satisfies a band gap of 1.5-5.5 eV: a) Cation doping, wherein the cation is selected from Li + Na + K + 、Rb + Cs + Mg² + Ca² + Sr² + Ba² + Al³ + Ga³ + In³ + Sn 4+ Sb³ + Sb 5+ Bi³ + ,Sc³ + Ti 4+ V³ + V 4+ V 5+ Cr³ + Cr 4+ Mn² + Mn³ + Mn 4+ Fe² + Fe³ + Co² + Co³ + Ni² + Ni³ + Cu² + Zn² + Y³ + Zr 4+ 、Nb 5+ Mo 6+ Ru 4+ 、Rh³ + Pd² + Ag + La³ + Ce³ + Ce 4+ Pr³ + Pr 4+ 、Nd³ + Sm³ + Eu³ + Gd³ + Tb³ + 、Tb 4+ Dy³ + Ho³ + Er³ + Tm³ + Yb³ + Lu³ + Hf 4+ Ta 5+ Re 4+ Re 6+ Os 4+ Ir 4+ Pt² + Pt 4+ and Au³ + At least one of them, with a doping ratio of 0.1-15 at%; b) Anion doping, wherein the anion is selected from one or more of B, C, N, F, P, S, Cl, Br and I, and the doping ratio is 0.5-10 at% c) Oxygen vacancy regulation, with an oxygen vacancy concentration of 10. 18 -10 21 cm -3 ; d) Defect engineering modification, dislocation / grain boundary density 10 14 -10 16 cm -2 ; The amount of photocatalytic active component added is 5-80 wt.% of the titanium dioxide powder mass; the amount of precursor compound added is based on the theoretical mass of the corresponding photocatalytic active oxide generated by its complete thermal decomposition, i.e., oxide equivalent.

3. The preparation method according to claim 1, characterized in that, The sintering aid is selected from at least one of the following components: a) Single oxide: Divalent metal oxides: magnesium oxide, calcium oxide, zinc oxide, copper oxide, nickel oxide, cobalt oxide (CoO), barium oxide, strontium oxide; Trivalent metal oxides: aluminum oxide, ferric oxide, cobalt oxide, bismuth oxide, chromium oxide, gallium oxide, antimony oxide; Oxides with a valence of three or higher: silicon dioxide, tin dioxide, manganese dioxide, zirconium dioxide, vanadium pentoxide, tungsten trioxide, niobium pentoxide, tantalum pentoxide, and phosphorus pentoxide; Low-melting-point networks / modified oxides: boron trioxide, lithium oxide, sodium oxide, potassium oxide; b) Rare earth oxides: Scandium oxide, yttrium oxide, lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, lutetium oxide; c) Titanates: Magnesium titanate (MgTiO3), Calcium titanate (CaTiO3), Barium titanate (BaTiO3), Strontium titanate (SrTiO3), Aluminum titanate (Al2TiO5); d) Natural minerals: talc, kaolin, bentonite, feldspar, wollastonite. e) Precursor compounds: The oxides in a) and b) are oxalates and / or carbonates that are insoluble in water, and the precursor compounds decompose in situ during the sintering heat treatment to generate the corresponding oxides; wherein, insoluble in water means: solubility in deionized water at 25℃ ≤ 0.1g / 100mL; The amount of sintering aid added is 0.2-30 wt.% of the titanium dioxide powder mass: for the sintering aids mentioned in a) to d), it is based on the actual added mass; for the sintering aids mentioned in d), it is based on the theoretical mass of the corresponding oxide generated by complete thermal decomposition, i.e., the oxide equivalent. The defect control agent is selected from at least one of the following components: a) High-valence metal oxides: niobium pentoxide, tantalum pentoxide, zirconium dioxide, hafnium dioxide, tin dioxide, germanium dioxide, tungsten trioxide, molybdenum trioxide, antimony pentoxide; b) Rare earth oxides: yttrium oxide, lanthanum oxide, gadolinium oxide, samarium oxide, cerium dioxide; c) Precursor compounds: the water-insoluble oxalates and / or carbonates corresponding to the oxides in components (a) and (b) above, wherein the precursor compounds decompose in situ during the sintering heat treatment to generate the corresponding oxides; wherein, "insoluble in water" means: solubility in deionized water at 25°C ≤0.1 g / 100 mL. The total amount of the defect control agent added is 0.1-15 wt.% of the titanium dioxide powder mass: for the defect control agents described in a) and b), it is based on their actual added mass; for the precursor compound described in c), it is based on the theoretical mass of the corresponding oxide generated by its complete thermal decomposition, i.e., the oxide equivalent.

4. The preparation method according to claim 1, characterized in that, In step S1, the organic additive includes at least one of binders, plasticizers, dispersants, surfactants, rheology modifiers, and defoamers; The organic additives are used alone or in combination, with a total addition amount of 0.1-30 wt.% of the total mass of titanium dioxide powder, defect control agent, sintering aid, and photocatalytic active component. The adhesive is selected from any one or more of polyethylene oxide, sodium alginate, chitosan, polyurethane emulsion, polyacrylamide, polyvinyl alcohol, methylcellulose, hydroxypropyl methylcellulose, ethylcellulose, polyethylene glycol, polyacrylic acid, polyvinyl acetate, starch and its derivatives; The plasticizer is selected from any one or more of the following: triethyl acetylglucosamine citrate, epoxidized soybean oil, polycaprolactone, glycerin, dibutyl phthalate, triethyl citrate, polyethylene glycol, sorbitol, and dioctyl sebacate. The dispersant is selected from any one or more of the following: polycarboxylate superdispersant, polymaleic anhydride, polyaspartic acid, ammonium polyacrylate, sodium polyacrylate, tetramethylammonium hydroxide, ammonium citrate, gum arabic, and polyvinylpyrrolidone. The surfactant is selected from any one or more of the following: sorbitan monooleate, cocamidopropyl betaine, perfluoropolyethers, sodium lauryl sulfate, hexadecyltrimethylammonium bromide, polysorbate 80, octylphenyl polyoxyethylene ether, lecithin, and fluorocarbon surfactants. The rheology modifier is selected from any one or more of guar gum, gellan gum, polyacrylic acid thickeners, organic modified montmorillonite, xanthan gum, sodium carboxymethyl cellulose, bentonite, fumed silica and polyacrylamide; The defoamer is selected from one or more of polydimethylsiloxane, polyether defoamer, isooctanol, n-octanol, silicone oil, polyether-modified siloxane, and mineral oil; The pH adjuster is at least one of ammonia and hydrochloric acid; The reinforcing phase is fibers and / or whiskers, selected from any one or more of the following: 1) Inorganic fibers: glass fiber, basalt fiber, silicon carbide fiber, alumina fiber, mullite fiber, quartz fiber, potassium titanate fiber; 2) Ceramic whiskers: silicon carbide whiskers, zinc oxide whiskers, calcium sulfate whiskers, silicon nitride whiskers, barium titanate whiskers, aluminum borate whiskers, magnesium borate whiskers, sodium titanate whiskers, potassium titanate whiskers, titanium dioxide whiskers, aluminum oxide whiskers, calcium carbonate whiskers. 3) Natural mineral fibers: sepiolite fiber, attapulgite fiber, wollastonite fiber, palygorskite fiber, tremolite fiber, actinolite fiber, vermiculite fiber, pyrophyllite fiber, sillimanite fiber, glauconite fiber, tourmaline fiber, palygorskite fiber; 4) Synthetic organic fibers: polyacrylonitrile fiber, polyvinyl alcohol fiber, aramid fiber, polyimide fiber; The reinforcing phase has an aspect ratio ≥ 10, a length of 1-500 μm, and a diameter of 0.1-50 μm. The titanium dioxide-based composite slurry has a solid content of 20-70 vol.% and a pH of 2-14. The amounts of organic additives and reinforcing phases added are based on the total mass of titanium dioxide powder, defect control agent, sintering aid, and photocatalytic active components, and are as follows: Adhesive 1-20 wt.%; Dispersant 0.1-5 wt.%; Plasticizer 0.1-10 wt.%; Surfactant 0.01-5 wt.%; Rheology modifier 0.1-10 wt.%; Defoamer 0.05-10 wt.%; pH adjuster 0.01-10 wt.%; Reinforcing phase: 0.01-30 wt.% of fibers or 0.01-50 wt.% of whiskers.

5. The preparation method according to claim 1, characterized in that, In step S1, the homogeneous solution is uniformly dispersed by mechanical stirring; the titanium dioxide-based composite slurry is uniformly dispersed by mechanical stirring and / or ball milling. The uniform dispersion of the homogeneous solution is achieved by mechanical stirring at a rate of 10-1800 rpm for 0.1-60 min, using an inert stirring paddle, and maintaining a distance of 0.01-2 cm between the paddle blades and the bottom of the slurry container. When mechanical stirring is used to uniformly disperse the titanium dioxide-based suspension slurry and the titanium dioxide-based composite slurry, the stirring speed is 20-3000 rpm; the stirring time is 15-1500 min; the stirring paddle is made of inert material; and the distance between the stirring paddle blade and the bottom of the slurry container is 0.1-20 cm. When uniformly dispersing the titanium dioxide-based suspension slurry and the titanium dioxide-based composite slurry using ball milling, the ball milling jar used for ball milling is made of an inert material; the ball-to-material weight ratio is 0.2-12; the ball milling time is 30-1500 min; the diameter of a single grinding ball is 0.2-12 mm, and the average diameter is 3-8 mm.

6. The preparation method according to claim 1, characterized in that, In step S2, the organic foam is made of polyurethane, melamine formaldehyde, or polystyrene; the pore density of the organic foam ranges from 6 to 70 PPI, and its macroscopic shape is any one of the following: cylinder, cube, cuboid, sphere, ellipsoid, torus, prism, pyramid, polyhedron, honeycomb block, sheet, arc, arch, tubular, hollow spherical shell, or any combination or deformation thereof. The impregnation is carried out using normal pressure, negative pressure assisted, or alternating negative and normal pressure methods; the impregnation process is carried out at 25±20℃, the normal pressure impregnation time is 30-1800 seconds, and the number of negative and normal pressure alternating impregnations is 1-5 times per impregnation cycle; The negative pressure assistance involves completely immersing the organic foam in the titanium dioxide-based composite slurry described in step S1, then evacuating the composite slurry to boiling point within 3 minutes, maintaining boiling for 0.5-10 minutes to ensure that all air in the system is expelled, and then restoring it to ambient pressure. The pressure of the extrusion desizing is controlled at 0.05-5.0 MPa, and the thickness of the organic foam after extrusion is compressed to 30-95% of the original thickness; the centrifugal desizing speed is 500-2000 rpm, and the centrifugation time is 10-600 seconds; The drying process employs a programmed temperature increase method, with a temperature range of 20~95℃ and a relative humidity decreasing from ≥70% to <10%, drying until the mass change rate is <20% / h. After each impregnation-desizing-drying cycle, the mass gain rate of the composite slurry loaded in the organic foam is 50-500%. After 2-5 cycles, the cumulative loading of the composite slurry reaches 150-1000% of the original mass of the organic foam, forming a coating thickness of 0.1-3.0 mm, a coating thickness variation coefficient of <30%, and a pore blockage rate of <40%.

7. The preparation method according to claim 1, characterized in that, In step S3, the natural air drying is carried out in a ventilated environment with a temperature of 5-45℃, a relative humidity of 30-90%, a ventilation rate of 0.1-10.0 m / s, and a natural air drying time of 2-24 hours. The heating program for the drying process is as follows: the temperature is increased from room temperature to 50-95℃ at a rate of 0.01-10.00℃ / min, and the temperature is maintained for 4-8 hours. The airflow rate inside the oven is 0.01-10.00 m / s, and the drying endpoint is a mass change rate of <0.1% / h. The degumming heat treatment includes: The first stage involves raising the temperature at a rate of 1-10℃ / min to 150-250℃ and holding it for 1-360 min. In the second stage, the temperature is increased to 350-450℃ at a rate of 0.5-10℃ / min, and then held for 1-360 min. The third stage involves raising the temperature at a rate of 0.5-10℃ / min to 550-600℃ and holding it for 1-360 min. The degumming heat treatment process is carried out under vacuum or atmospheric conditions. The vacuum conditions are: no gas is introduced and the absolute pressure inside the furnace is maintained below 100 Pa. The atmospheric conditions are: at least one of helium, argon, nitrogen, ammonia, air and oxygen is introduced, the gas flow rate is 0-9000 mL / min, and the pressure inside the furnace is maintained at gauge pressure +50 to +9000 Pa.

8. The preparation method according to claim 1, characterized in that, In step S4, the controlled sintering heat treatment temperature is 900-1700℃, the heating rate is 2-20℃ / min, and the holding time is 0.01-24 hours; The controlled sintering heat treatment is carried out under vacuum or atmospheric conditions. The vacuum conditions are: no gas is introduced and the absolute pressure inside the furnace is maintained below 10 Pa. The atmospheric conditions are: at least one of hydrogen, helium, argon, nitrogen, ammonia, air and oxygen is introduced, the gas flow rate is 0-9000 mL / min, and the pressure inside the furnace is maintained at gauge pressure +50 to +9000 Pa.

9. TiO2-based photocatalytic foam ceramic obtained by the preparation method according to any one of claims 1 to 8.

10. The application of the TiO2-based photocatalytic foam ceramic prepared by the preparation method according to any one of claims 1 to 8 in i) the degradation of organic pollutants or water treatment; ii) the application in the preparation of an apparatus for degrading organic pollutants or a water treatment apparatus.

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