Titanium-dioxide-based double-layer hollow material, preparation method thereof, and application thereof in photocatalytic treatment of hydrogen sulfide

Abstract

A preparation method of a titanium-dioxide-based double-layer hollow material includes the following steps: (1) using polystyrene nanospheres with particle size of 180 nm as a template, tetrabutyl titanate as a precursor, to prepare hollow titanium dioxide by calcining; (2) subjecting said hollow titanium dioxide to carboxylation modification to prepare carboxylated titanium dioxide; and (3) dispersing said carboxylated titanium dioxide in ethanol, using chromic nitrate nonahydrate as an assembly agent and trimesic acid as a crosslinking agent to carry out layer-by-layer self-assembly so as to prepare the titanium-dioxide-based double-layer hollow material.

Claims

1. A preparation method of a titanium-dioxide-based double-layer hollow material, which comprises following steps: (1) using polystyrene nanospheres with particle size of 180 nm as a template, tetrabutyl titanate as a precursor, to prepare hollow titanium dioxide by calcining; (2) subjecting said hollow titanium dioxide to carboxylation modification to prepare carboxylated titanium dioxide; (3) dispersing said carboxylated titanium dioxide in ethanol, using chromic nitrate nonahydrate as an assembly agent and trimesic acid as a crosslinking agent to carry out layer-by-layer self-assembly so as to prepare the titanium-dioxide-based double-layer hollow material.

2. The preparation method of a titanium-dioxide-based double-layer hollow material according to claim 1, wherein in step (1), heating styrene aqueous solution to 80 to 90 C. in the presence of a surfactant in nitrogen atmosphere; and adding an aqueous solution of initiator in drops, polymerizing for 10 to 20 hours; and after the polymerization, adding sodium chloride to obtain a precipitate, and then washing the precipitate with deionized water and then drying at 60 C. to prepare a polystyrene nanosphere.

3. The preparation method of a titanium-dioxide-based double-layer hollow material according to claim 1, wherein in step (1), calcining is carried out at 500 to 700 C. for 2 to 3 hours, and the rate of heating is 1 to 5 C./min.

4. The preparation method of a titanium-dioxide-based double-layer hollow material according to claim 1, wherein in step (1), adding tetrabutyl titanate into acetonitrile to prepare the tetrabutyl titanate solution by stirring; adding polystyrene nanospheres into a solvent to prepare a polystyrene suspension with ultrasonic dispersion; and then dripping ammonia, deionized water and tetrabutyl titanate solution into the polystyrene suspension, stirring for 1 hour to prepare a mixed liquid; and then washing the mixed liquid and centrifuging to obtain solid, drying and calcining the solid to prepare hollow titanium dioxide particles; the mass ratio of tetrabutyl titanate, polystyrene nanospheres and ammonia is 30:1:20.

5. The preparation method of a titanium-dioxide-based double-layer hollow material according to claim 1, wherein in step (2), the carboxylation modification is adding the hollow titanium dioxide to an ethanol solution of a silane coupling agent and stirring for 8 to 10 hours to give a solid; and then taking the solid into an the N, N-dimethylformamide solution of succinic anhydride and stirring for 8 to 10 hours to obtain carboxylated titanium dioxide; the mass ratio of titanium dioxide, silane coupling agent and succinic anhydride is 50:1:1.

6. The preparation method of a titanium-dioxide-based double-layer hollow material according to claim 1, wherein in step (3), each self-assembly step is adding an ethanol solution of chromium nitrate nonahydrate to the carboxylated titanium dioxide ethanol dispersion, stirring and then centrifuging with ethanol and then adding a trimesic acid ethanol solution to continue stirring; then washing and centrifuging to remove the liquid.

7. The preparation method of a titanium-dioxide-based double-layer hollow material according to claim 1, wherein in step (3), the mass ratio of carboxylated titanium dioxide, chromic nitrate nonahydrate and trimesic acid is 20:1:1, and the number of times of layer-by-layer self-assembly is 10 to 20.

8. Titanium-dioxide-based double-layer hollow material prepared by the preparation method according to claim 1.

9. A method of photocatalytically treating hydrogen sulfide comprising: providing the titanium-dioxide-based double-layer hollow material according to claim 8; and treating hydrogen sulfide with the titanium-dioxide-based double-layer hollow material.

10. A method of treating polluted gas comprising: providing the titanium-dioxide-based double-layer hollow material according to claim 8; and treating polluted gas with the titanium-dioxide-based double-layer hollow material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1. TEM images of polystyrene.

(2) FIG. 2. SEM images of polystyrene.

(3) FIG. 3. TEM images of hollow TiO.sub.2.

(4) FIG. 4. SEM images of hollow TiO.sub.2.

(5) FIG. 5. TEM images of TiO.sub.2@MIL-100.

(6) FIG. 6. SEM images of TiO.sub.2@MIL-100.

(7) FIG. 7. Photocatalytic effect of TiO.sub.2@MIL-100 on H.sub.2S.

DETAILED DESCRIPTIONS

Embodiment 1

(8) Synthesis of Polystyrene Nanospheres.

(9) 0.05 g of sodium dodecyl sulfate and 15 g of styrene monomer were added to 80 mL of water under stirring, and the temperature was raised to 80 C. under nitrogen atmosphere. Thereafter, 20 mL of an aqueous solution containing 0.15 g of potassium persulfate was gradually added dropwise. The mixture was stirred for an additional 10 hours and the polystyrene nanospheres were precipitated by the addition of sodium chloride. The final product was washed several times with ion-exchanged water and dried in an oven. The TEM and SEM images of polystyrene were shown in FIG. 1 and FIG. 2, and the structure was uniform and the particle size was 180 nm.

(10) Synthesis of Hollow TiO.sub.2.

(11) 0.5 mL of tetrabutyl titanate was added to 20 mL of acetonitrile and the stirring was continued for 10 minutes. Then, 0.017 g of polystyrene nanospheres were added to 90 ml of acetonitrile and dispersed by sonication. And 0.3 mL of aqueous ammonia, 0.06 ml of deionized water and 20 mL of a tetrabutyl titanate solution were added dropwise to the prepared polystyrene suspension. The mixture was stirred at room temperature for 1 hour to complete the chemical reaction. The product was washed in ethanol and centrifuged three times and dried. And then calcined at 500 C. at a heating rate of 1 C. per minute for 2 hours. FIG. 3 and FIG. 4 show the TEM and SEM images of the hollow TiO.sub.2. Through the figures it can be seen that the structure of the hollow TiO.sub.2 is even.

(12) Synthesis of Carboxylated TiO.sub.2.

(13) The hollow TiO.sub.2 was added to the ethanol solution of the silane coupling agent for 8 hours. After centrifugation, it was transferred to a solution of succinic anhydride in N, N-dimethylformamide to continue stirring for 8 hours. The mass ratio of titanium dioxide, silane coupling agent and succinic anhydride is 50:1:1.

(14) Synthesis of TiO.sub.2@MIL-100 Double Hollow Material.

(15) The carboxylated TiO.sub.2 was dispersed in 10 ml of ethanol, and then 10 mL of a solution of chromium nitrate nonahydrate was added and stirred at room temperature for 15 minutes. After centrifugation with ethanol and then 10 ml of a solution of purified terephthalic acid in ethanol was added and stirred for 30 minutes. After centrifugation, the above procedure was repeated 20 times to obtain TiO.sub.2@MIL-100 double-layer hollow material.

(16) FIG. 5 and FIG. 6 shows the TEM and SEM images of TiO.sub.2@MIL-100 double-layer hollow material.

Embodiment 2

(17) Photocatalysis of H.sub.2S.

(18) A batch reactor (1.5 L volume) containing a quartz glass was used for photocatalytic oxidation of hydrogen sulfide. 0.5 g of the above-prepared catalyst TiO.sub.2@MIL-100 double-layer hollow material was deposited on quartz glass and then the reactor was evacuated. Next, 1 L of high purity air and 0.5 L of mixed gas containing H.sub.2S (100 ppm concentration) were introduced into the batch reactor and the concentration of H.sub.2S was analyzed using GC.

(19) FIG. 7 shows photocatalytic effect of TiO.sub.2@MIL-100 on H.sub.2S.

(20) Through the above embodiment, it shows that the TiO.sub.2@MIL-100 hollow material synthesized by the present invention has good effect on the photocatalytic hydrogen sulfide gas; and its preparation process is simple, raw materials is easy to get, has the application prospect in the treatment of the toxic hydrogen sulfide gas.

Embodiment 3

(21) Synthesis of Polystyrene Nanospheres.

(22) 0.05 g of sodium dodecyl sulfate and 15 g of styrene monomer were added to 80 mL of water under stirring, and the temperature was raised to 90 C. under nitrogen atmosphere. Thereafter, 20 mL of an aqueous solution containing 0.15 g of potassium persulfate was gradually added dropwise. The mixture was stirred for an additional 8 hours and the polystyrene nanospheres were precipitated by the addition of sodium chloride. The final product was washed several times with ion-exchanged water and dried in an oven. The structure was uniform and the particle size was 180 nm.

(23) Synthesis of Hollow TiO.sub.2.

(24) 0.5 mL of tetrabutyl titanate was added to 20 mL of acetonitrile and the stirring was continued for 20 minutes. Then, 0.017 g of polystyrene nanospheres were added to 90 ml of acetonitrile and dispersed by sonication. And 0.3 mL of aqueous ammonia, 0.06 ml of deionized water and 20 mL of a tetrabutyl titanate solution were added dropwise to the prepared polystyrene suspension. The mixture was stirred at room temperature for 2 hour to complete the chemical reaction. The product was washed in ethanol and centrifuged three times and dried. And then calcined at 700 C. at a heating rate of 5 C. per minute for 2 hours. The structure of the hollow TiO.sub.2 is even.

(25) Synthesis of Carboxylated TiO.sub.2.

(26) The hollow TiO.sub.2 was added to the ethanol solution of the silane coupling agent for 10 hours. After centrifugation, it was transferred to a solution of succinic anhydride in N, N-dimethylformamide to continue stirring for 10 hours. The mass ratio of titanium dioxide, silane coupling agent and succinic anhydride is 50:1:1.

(27) Synthesis of TiO.sub.2@MIL-100 Double Hollow Material.

(28) The carboxylated TiO.sub.2 was dispersed in 10 ml of ethanol, and then 10 mL of a solution of chromium nitrate nonahydrate was added and stirred at room temperature for 30 minutes. After centrifugation with ethanol and then 10 ml of a solution of purified terephthalic acid in ethanol was added and stirred for 60 minutes at 25 C. After centrifugation, the above procedure was repeated 10 times to obtain TiO.sub.2@MIL-100 double-layer hollow material. It has a good photocatalytic effect on hydrogen sulfide gas, reaching more than 90% in 1 hour.