CN101890370B - Nano-titanium dioxide and polyphosphazene based composite optical catalyst and preparation method thereof - Google Patents

Abstract

A composite photocatalyst based on nano-titanium dioxide and polyphosphazene in the technical field of catalyst preparation and a preparation method thereof. In 2500 parts by weight of an organic solvent, the dispersion liquid was obtained by ultrasonic dispersion; further adding 73 parts by weight of an acid-binding agent, the dispersion liquid of the target product was obtained by heating a water bath, and after filtration, washing and drying, a composite compound based on nano-titanium dioxide and polyphosphazene was obtained. catalyst of light. The present invention is a composite photocatalyst based on nano-titanium dioxide and polyphosphazene with a core-shell structure obtained by coating modified Degussa P25 nano-titanium dioxide with polyphosphazene. Compared with P25, the photocatalyst has excellent adsorption performance for target organic pollutants and shows higher photocatalytic activity under ultraviolet light irradiation.

Description

Composite photocatalyst based on nano-titanium dioxide and polyphosphazene and its preparation method

technical field

The invention relates to a method in the technical field of catalysts, in particular to a composite photocatalyst based on nano titanium dioxide and polyphosphazene and a preparation method thereof.

Background technique

With the acceleration of industrialization, a large amount of industrial waste containing various organic compounds is discharged into nature, causing serious pollution to the ecology. To solve this pressing problem, photocatalytic degradation technology has attracted much attention in the past two decades due to its higher efficiency compared with traditional biodegradation pathways. Anatase nano-titanium dioxide has the characteristics of high catalytic activity, non-toxicity and good chemical stability, and is one of the most commonly used photocatalysts. However, the adsorption of titanium dioxide to target organic pollutants is poor, the catalytic activity is not high in the environment of low pollutant concentration, and it is difficult to recover after use, which greatly limits its practical application. Therefore, enhancing the adsorption capacity of nano-TiO to organic matter by surface modification is an effective way to further improve its photocatalytic activity and efficiency.

Found through literature search to prior art, Holland " applied catalysis, B series: environment " periodical in 2008 the 79th volume 2 phase 171～178 pages (T.Guo, ZPBai, C.Wu, T.Zhu, Influence of relative humidity on the photocatalytic oxidation (PCO) of toluene by TiO ₂ loaded on activated carbon fibers: PCO rate and intermediates accumulation, Applied Catalysis B: Environmental, 2008, 79(2): 171～178) reported a nano titanium dioxide A surface-loaded composite photocatalyst formed by loading particles on the surface of porous activated carbon fibers. The photocatalyst has excellent adsorption capacity and photocatalytic activity for toluene, but the firmness of this method is relatively weak, and nano-titanium dioxide particles are easily removed from the porous activated carbon fibers. The surface falls off, limiting the recycling of the catalyst. British "Journal of Materials Chemistry" in 2002, Volume 12, No. 5, Page 1391-1396 (T.Tsumura, N.Kojitani, I.Izumi, N.Iwashita, M.Toyoda, M.Inagaki, Carbon coating of anatase -type TiO ₂ and photoactivity, Journal of Material Chemistry, 2002, 12 (5): 1391-1396) has reported a kind of method that obtains core-shell type composite photocatalyst with porous carbon material coating nano titanium dioxide particle, although this method can Effectively enhance the adsorption capacity of titanium dioxide, but usually requires high-temperature carbonization of the precursor, and the steps are cumbersome and harsh.

Contents of the invention

Aiming at the above-mentioned deficiencies in the prior art, the present invention provides a composite photocatalyst based on nano-titanium dioxide and polyphosphazene and a preparation method thereof, which is obtained by coating and modifying Degussa P25 nano-titanium dioxide with polyphosphazene. Structure of Nanosized TiO2 and Polyphosphazene Based Composite Photocatalysts. Compared with P25, the photocatalyst has excellent adsorption performance for target organic pollutants and shows higher photocatalytic activity under ultraviolet light irradiation.

The present invention is realized through the following technical solutions, and the present invention specifically comprises the following steps:

Step 1, placing 1 part by weight of hexachlorocyclotriphosphazene, 2.16 parts by weight of bisphenol S and 1 to 5 parts by weight of nano-titanium dioxide in 2500 parts by weight of an organic solvent, and obtaining a dispersion liquid through ultrasonic dispersion;

The nano titanium dioxide is Degussa P25 nano titanium dioxide.

The organic solvent is a mixed solvent of tetrahydrofuran and absolute ethanol, and the volume ratio is 1:1.

In step 2, 73 parts by weight of an acid-binding agent were further added, and a dispersion liquid of the target product was obtained by heating in a water bath, and a composite photocatalyst based on nano-titanium dioxide and polyphosphazene was obtained after filtering, washing and drying.

The acid-binding agent is triethylamine.

The warming water bath refers to: reacting in a 40°C ultrasonic water bath for 5 hours,

The power of the ultrasonic wave is 100 watts.

The present invention relates to the catalyst prepared by the above method having a core-shell structure, with Degussa P25 nano-titanium dioxide as the core and polyphosphazene as the shell, wherein the structural formula of polyphosphazene is as follows:

Compared with the prior art, the present invention has the following beneficial effects: (1) the preparation method of the present invention is simple and effective, and the conditions are mild; (2) the polyphosphazene of the present invention has a unique pore structure and adsorption performance, which is The composite photocatalyst based on nano-titanium dioxide and polyphosphazene provides high specific surface area and adsorption capacity, so that the target organic pollutants can be effectively enriched on the surface of titanium dioxide particles, forming a local high reactant concentration in the photocatalytic center, At the same time, the polyphosphazene coating layer has good permeability to ultraviolet light, thereby greatly improving the photocatalytic activity and efficiency; (3) the polyphosphazene of the present invention is an organic-inorganic heterogeneous compound with a highly cross-linked structure. It is a polymer with good chemical and thermal stability, and the reactive monomer can be easily polymerized and cross-linked in situ on the surface of the target substrate to form a polyphosphazene coating with uniform thickness and controllable thickness. Therefore, polyphosphazene is a kind of An ideal packaging material. Coating nano-titanium dioxide with it can form a firm "protective layer" on the surface of nano-titanium dioxide particles, effectively preventing the deactivation and loss of the photocatalyst center during use. In addition, the highly cross-linked organic-inorganic hybrid structure can also make the polyphosphazene coating itself effectively resist the photocatalytic reaction, so that the composite photocatalyst based on nano-titanium dioxide and polyphosphazene can be recycled efficiently and stably.

Description of drawings

Fig. 1 is the synthetic route and chemical structure schematic diagram of preparing polyphosphazene cladding layer;

Fig. 2 is the mechanism of preparing the composite photocatalyst based on nano titanium dioxide and polyphosphazene;

Fig. 3 is the Fourier transform infrared spectrogram of the composite photocatalyst based on nano titanium dioxide and polyphosphazene that embodiment 1 makes;

Fig. 4 is the X-ray diffraction spectrogram of the composite photocatalyst based on nano titanium dioxide and polyphosphazene that embodiment 1 makes;

Fig. 5 is the scanning electron micrograph and the transmission electron micrograph of the composite photocatalyst based on nano titanium dioxide and polyphosphazene that embodiment 1 makes;

Fig. 6 is the scanning electron micrograph and the transmission electron micrograph of the composite photocatalyst based on nano titanium dioxide and polyphosphazene that embodiment 2 makes;

7 is a scanning electron micrograph and a transmission electron micrograph of the composite photocatalyst based on nano-titanium dioxide and polyphosphazene prepared in Example 3.

Detailed ways

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

As shown in Figure 1, it is the synthetic route and the chemical structure of the polyphosphazene coating layer prepared by the following examples, in the figure: hexachlorocyclotriphosphazene and bisphenol S are under the condition that triethylamine is used as an acid-binding agent , polycondensation reaction occurs in situ on the surface of nano-titanium dioxide particles, and the generated hydrogen chloride is absorbed by triethylamine to form triethylamine hydrochloride.

As shown in Figure 2, it is the mechanism illustration based on the composite photocatalyst of nano-titanium dioxide and polyphosphazene prepared by the following examples, wherein: in the initial stage of polycondensation reaction, polyphosphazene is in the form of primary nanoparticles under the action of ultrasonic waves exist. Because primary nanoparticles have high surface energy, they easily adhere to the surface of nano-TiO2 particles. Then, as the polycondensation reaction proceeds, the polyphosphazene adhered to the surface of the nano-titanium dioxide particles is cross-linked, thereby forming a coating layer with a highly cross-linked structure. In other words, in the process of forming nano-TiO2/polyphosphazene core-shell structure, nano-TiO2 played the role of "in situ template".

Example 1

In a 100mL round bottom flask, disperse 0.02g of hexachlorocyclotriphosphazene, 0.0432g of bisphenol S and 0.05g of Degussa P25 nano-titanium dioxide in a mixed solvent of 60mL of tetrahydrofuran and absolute ethanol (volume ratio of 1:1 ), ultrasonic treatment for 30 minutes to make the dispersion uniform. Then, 2 mL of triethylamine was added to the above dispersion liquid, and reacted in a 40° C., 100 W ultrasonic water bath for 5 hours. After the reaction, the target product was centrifuged at a speed of 3500 rpm, and the solvent was removed after 15 minutes of separation. The product was washed three times with acetone and deionized water respectively, and then dried in an oven at 80°C for 10 hours to obtain a white powder composite photocatalyst based on nano-titanium dioxide and polyphosphazene.

Implementation effect of this embodiment: FIG. 3 is a Fourier transform infrared spectrogram of the prepared composite photocatalyst based on nano-titanium dioxide and polyphosphazene. It can be seen from the figure that the absorption peaks at 3200～3600cm ^-1 (a) and 1630cm ^-1 (b) are respectively attributed to the stretching vibration and bending vibration of the hydroxyl groups on the surface of nano-TiO2. The broad peak at 400 to 800 cm ^-1 (c) is attributed to the bending vibration of the Ti-O bond. Obviously, the spectrogram of the composite photocatalyst based on nano-titanium dioxide and polyphosphazene not only contains all the characteristic peaks of polyphosphazene (C=C(Ph): 1591cm ^-1 (e) and 1490cm ^-1 (f) ; O=S=O: 1294cm ^-1 (g) and 1154cm ^-1 (i); P=N: 1187cm ^-1 (h); PN: 880cm ^-1 (k); PO-(Ph): 941cm ^-1 (j)), and also contains the characteristic peak of nano-titanium dioxide (Ti-O: 400-800cm ^-1 (l)), indicating that the product is a composite of nano-titanium dioxide and polyphosphazene.

As shown in Figure 4, it is the X-ray diffraction spectrum of the prepared composite photocatalyst based on nano-titanium dioxide and polyphosphazene, wherein: P25 nano-titanium dioxide contains two crystal forms: anatase and rutile. The spectrogram of the prepared composite photocatalyst based on nano-titanium dioxide and polyphosphazene not only contains all the diffraction peaks of nano-titanium dioxide, but also contains the characteristic peaks of polyphosphazene (14.5 °, broad amorphous peak, as indicated by the asterisk ), indicating that the product is a composite of nano-titanium dioxide and polyphosphazene, and there is no change in the crystal form of nano-titanium dioxide after the composite.

As shown in Figure 5, it is a scanning electron micrograph and a transmission electron micrograph of the composite photocatalyst based on nano-titanium dioxide and polyphosphazene prepared. The product has a core-shell structure, with nano-titanium dioxide as the core, polyphosphazene as the shell, and polyphosphine The thickness of the nitrile coating layer is uniform, about 3-5 nm. It shows that this example successfully prepared the composite photocatalyst based on nano titanium dioxide and polyphosphazene.

The BET specific surface area of the composite photocatalyst based on nano-titanium dioxide and polyphosphazene prepared in this example is 65.6m ² g ^-1 , which is higher than that of P25 nano-titanium dioxide (46.5m ² g ^-1 ) before coating modification, indicating that It has a porous structure. Using methylene blue as a template organic pollutant, the photocatalytic degradation experiment was carried out under ultraviolet light conditions. The results showed that the prepared composite photocatalyst based on nano-titanium dioxide and polyphosphazene had excellent adsorption capacity for target organic compounds, and the adsorption capacity was unchanged. 19 times that of P25 nano-titanium dioxide, and the photocatalytic activity is 20.1% higher than that of unmodified P25 nano-titanium dioxide. At the same time, the prepared composite photocatalyst based on nano titanium dioxide and polyphosphazene also has good stability and can be recycled.

Example 2

In a 100mL round bottom flask, disperse 0.02g of hexachlorocyclotriphosphazene, 0.0432g of bisphenol S and 0.03g of Degussa P25 nano-titanium dioxide in a mixed solvent of 60mL of tetrahydrofuran and absolute ethanol (volume ratio of 1:1 ), ultrasonic treatment for 30 minutes to make the dispersion uniform. Then, 2 mL of triethylamine was added to the above dispersion liquid, and reacted in a 40° C., 100 W ultrasonic water bath for 5 hours. After the reaction, the target product was centrifuged at a speed of 3500 rpm, and the solvent was removed after 15 minutes of separation. The product was washed three times with acetone and deionized water respectively, and then dried in an oven at 80°C for 10 hours to obtain a white powder composite photocatalyst based on nano-titanium dioxide and polyphosphazene.

As shown in FIG. 6 , it is a scanning electron micrograph and a transmission electron micrograph of the prepared composite photocatalyst based on nano-titanium dioxide and polyphosphazene.

Example 3

In a 100mL round bottom flask, disperse 0.02g of hexachlorocyclotriphosphazene, 0.0432g of bisphenol S and 0.09g of Degussa P25 nano-titanium dioxide in a mixed solvent of 60mL of tetrahydrofuran and absolute ethanol (volume ratio of 1:1 ), ultrasonic treatment for 30 minutes to make the dispersion uniform. Then, 2 mL of triethylamine was added to the above dispersion, and reacted in a 40°C, 100W ultrasonic water bath for 5 hours. After the reaction, the target product was centrifuged at a speed of 3500 rpm, and the solvent was removed after separation for 15 minutes. The product was washed three times with acetone and deionized water respectively, and then dried in an oven at 80°C for 10 hours to obtain a white powder composite photocatalyst based on nano-titanium dioxide and polyphosphazene.

As shown in FIG. 7 , it is a scanning electron micrograph and a transmission electron micrograph of the prepared composite photocatalyst based on nano-titanium dioxide and polyphosphazene.

Claims (7)

1. the preparation method based on the composite photo-catalyst of nano titanium oxide and poly phosphazene is characterized in that, may further comprise the steps:

Step 1 places 2500 weight portion organic solvents with 1 weight portion hexachlorocyclotriphosphazene, 2.16 weight portion bisphenol Ss and 1～5 weight portion nano titanium oxide, obtains dispersion liquid through ultrasonic dispersion;

Step 2 further adds 73 weight portion acid binding agents, through adding the dispersion liquid that tepidarium obtains target product, and must be after the filtration washing drying based on the composite photo-catalyst of nano titanium oxide and poly phosphazene.

2. the preparation method of the composite photo-catalyst based on nano titanium oxide and poly phosphazene according to claim 1 is characterized in that said nano titanium oxide is a Degussa P25 nano titanium oxide.

3. the preparation method of the composite photo-catalyst based on nano titanium oxide and poly phosphazene according to claim 1 it is characterized in that said organic solvent is the mixed solvent of oxolane and absolute ethyl alcohol, and volume ratio is 1: 1.

4. the preparation method of the composite photo-catalyst based on nano titanium oxide and poly phosphazene according to claim 1 is characterized in that said acid binding agent is a triethylamine.

5. the preparation method of the composite photo-catalyst based on nano titanium oxide and poly phosphazene according to claim 1 is characterized in that, describedly adds tepidarium and is meant: reaction is 5 hours in 40 ℃ of ultrasound baths.

6. the preparation method of the composite photo-catalyst based on nano titanium oxide and poly phosphazene according to claim 5 is characterized in that said hyperacoustic power is 100 watts.

7. a composite photo-catalyst for preparing according to arbitrary described method among the claim 1-6 is characterized in that having nucleocapsid structure, is nuclear with Degussa P25 nano titanium oxide, and poly phosphazene is a shell, and wherein: the structural formula of poly phosphazene is following:

Images