Kit for wastewater treatment, and manufacturing method for and use of photocatalyst

Abstract

The present invention relates to a kit for water treatment, comprising: a photocatalyst including at least one of SnFe.sub.2O.sub.4, ZnFe.sub.2O.sub.4, CuFe.sub.2O.sub.4, Fe.sub.3O.sub.4, MnFe.sub.2O.sub.4 and NiFe.sub.2O.sub.4; and an active oxide. The present invention also relates to a method for manufacturing a photocatalyst and a use of the prepared photocatalyst.

Claims

1. A method for manufacturing a photocatalyst, comprising the following steps: (A) dissolving a divalent metal precursor and an iron precursor in a first solvent to form a first precursor solution; (B) mixing a second solvent with the first precursor solution to form a first mixed solution, wherein the second solvent is miscible with the first solvent; (C) adding a third solvent into the first mixed solution to obtain a layered solution, wherein third solvent is located at an upper layer of the layered solution, and the first mixed solution is located at a lower layer of the layered solution; (D) stirring the layered solution for carrying the precursor solution from the first mixed solution into the third solvent to obtain a second mixed solution comprising a photocatalyst, wherein the photocatalyst includes at least one of SnFe.sub.2O.sub.4, ZnFe.sub.2O.sub.4, CuFe.sub.2O.sub.4, Fe.sub.3O.sub.4, MnFe.sub.2O.sub.4 and NiFe.sub.2O.sub.4; and (E) separating the photocatalyst from the second mixed solution through a centrifugation.

2. The method as claimed in claim 1, wherein the third solvent is immiscible with the second solvent, and the first solvent has a higher affinity toward the third solvent than that toward the second solvent.

3. The method as claimed in claim 1, wherein the iron precursor is a trivalent iron compound.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1A shows XRD spectra of the photocatalysts A to E prepared in Preparative examples 1 to 5.

(2) FIG. 1B is a TEM image of the photocatalyst F prepared in Preparative example 6.

(3) FIG. 2 is an IR spectrum of the photocatalyst A prepared in Preparative example 1.

(4) FIG. 3 is a magnetic analysis result of the photocatalyst D prepared in Preparative example 4.

(5) FIGS. 4A to 4D show the results of the photodegradation analysis of the examples of the present invention.

(6) FIGS. 5A and 5B show the results of the photodegradation analysis of the examples of the present invention.

(7) FIG. 6 shows the result of the photoderadation analysis of the example of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Manufacture of the Photocatalyst

Preparative Examples 1 to 5

(8) With reference to the following Table 1, appropriate amounts of the divalent metal precursor (SnCl.sub.2) and the iron precursor (Fe(NO.sub.3).sub.3) are dissolved in 22.5 ml of the first solvent (ethanol), wherein the content ratio (molar ratio) of the stannous ion and the ferric ion is 1:2. 3.75 ml of the ethanol solution dissolving with the divalent metal precursor and the iron precursor is added into 3.75 ml of the second solvent (chloroform), followed by adding 7.5 ml of the third solvent (sodium hydroxide (NaOH) aqueous solution, 1M) therein. The mixture is stirred at a speed of 400 rpm for 30 minutes. The upper-layer solution is separated and an appropriate amount of ethanol is added into the separated upper-layer solution, and then the precipitate is separated from the mixture solution of the upper-layer solution and ethanol and collected by the centrifugation. Then, the obtained precipitate is rinsed with ethanol and collected by the centrifugation several times, followed by performing the drying process to afford the photocatalyst A to E (SnFe.sub.2O.sub.4) prepared in the preparative examples 1 to 5.

(9) TABLE-US-00001 TABLE 1 Precursor Photo- Particle Energy SnCl.sub.2 (g) Fe(NO.sub.3).sub.3 (g) catalyst Size (nm) Gap (eV) Preparative 0.03 0.11 A 3.0 2.53 example 1 Preparative 0.05 0.21 B 4.3 2.53 example 2 Preparative 0.10 0.43 C 6.3 2.53 example 3 Preparative 0.20 0.85 D 12.6 2.53 example 4 Preparative 0.30 1.28 E 2.53 example 5 Preparative 0.03 0.11 F example 6

Preparative Example 6

(10) Referring to Table 1, appropriate amounts of divalent metal precursor (SnCl.sub.2) and the iron precursor (Fe(NO.sub.3).sub.3) are dissolved in the 22.5 ml of the first solvent (ethanol), wherein the content ratio (molar ratio) of the stannous ion and the ferric ion is 1:2. 3.75 ml of the ethanol solution dissolving with the divalent metal precursor and the iron precursor is added into 3.75 ml of the second solvent (chloroform), followed by adding 7.5 ml of the third solvent (sodium hydroxide (NaOH) aqueous solution, 1M) therein. The mixture is stirred at a speed of 400 rpm for 30 minutes. The upper-layer solution is separated and an appropriate amount of ethanol is added into the separated upper-layer solution, and then the supernatant is obtained from the mixture of the upper-layered solution and ethanol by the centrifugation. The obtained supernatant comprises the photocatalyst F of Preparative example 6. The particle size and the crystal characteristics of the photocatalyst F prepared by Preparative example 6 is analyzed by Transmission Electron Microscopy (TEM), and the analytical results are shown in FIG. 1B.

(11) Characterizations

(12) For detailed description, the properties of the prepared photocatalyst are optionally analyzed.

(13) Please refer to FIG. 1A, which shows results of the X-ray diffraction spectrum analysis (XRD) of the photocatalysts A to E prepared by Preparative examples 1 to 5. As shown in FIG. 1A, all the photocatalysts A to E have the diffraction peaks of SnFe.sub.2O.sub.4 (at the position marked by *). In addition, the photocatalyst E prepared by Preparative example 5 has the diffraction peak of -Fe.sub.2O.sub.3 because of the higher concentration of the precursor (at the position marked by #). Please refer to FIG. 1B, which shows the TEM result of the photocatlayst prepared by Preparative example 6. As shown in FIG. 1B, the particle size of the photocatalyst F prepared by Preparative example 6 is approximately 3 nm or less, and the d-spacing of the crystalline surface (311) of SnFe.sub.2O.sub.4 is approximately 0.258 nm. Please refer to FIG. 2, which shows the Infrared (IR) spectrum of the photocatalyst A prepared by Preparative example 1, wherein the reference is a commercialized iron oxide (CAS: 1317-61-9). As shown in FIG. 2, a peak of SnO at 630 cm.sup.1, and peaks of FeO at 580 cm.sup.1 and 445 cm.sup.1 are observed in the photocatalyst A. Hence, the results shown in FIG. 1A, FIG. 1B and FIG. 2 indicate that the photocatalysts A to F prepared by Preparative examples 1 to 6 comprise SnFe.sub.2O.sub.4.

(14) In addition, particle size of the photocatalysts A to E can be calculated according to the analytical results of the XRD spectra, and the energy gaps thereof can be calculated according to the UV-visible absorption spectra. The results are also shown in Table 1.

(15) Please refer to the following Table 2, which shows the Energy-Dispersive X-ray Spectroscopy (EDX) of the photocatalyst A prepared by Preparative example 1, wherein the comparative example is a commercialized iron oxide (CAS: 1317-61-9). Table 2 shows that the atomic ratio (atomic %) of Sn and Fe atom in the photocatalyst A is approximately 1:2, indicating that the photocatalyst A indeed comprises SnFe.sub.2O.sub.4.

(16) TABLE-US-00002 TABLE 2 Si Sn Fe O Pt Comparative 80.72 0 7.10 11.41 0.77 example Photocatalyst A 82.24 2.15 4.33 10.61 0.67

(17) With reference to FIG. 3, showing the magnetic analytical result of the photocatalyst D, the suspended photocatalyst D are attached to the side closed to the magnet after 30 seconds of magnetic attraction. It is proved that the prepared phototcatalyst has excellent magnetic property.

(18) Accordingly, as according to the results shown in FIGS. 1 to 3, Tables 1 and 2, the photocatalysts A to E prepared by the present invention do comprise SnFe.sub.2O.sub.4 and have excellent magnetic property, which are beneficial for recycling process.

(19) Photodegradation Analysis

(20) [Effect of the Light Sources]

(21) First, please refer to the following Table 3, the samples are prepared by different photocatalysts, active oxides, and simulated pollutants, wherein the concentration of the photocatalysts is 1.2710.sup.4M, the concentration of the active oxides is 2.5M, and the concentration of the stimulated pollutants is 1.2 mg/L.

(22) TABLE-US-00003 TABLE 3 Stimulated Sample Photocatalyst Active oxide pollutant 1 A H.sub.2O.sub.2 RhB 2 B 3 C 4 D 5 E 6 P25 7 P25 8 H.sub.2O.sub.2 9 P25: TiO.sub.2 photocatalyst from Degussa (Product name: AEROXIDE TIO.sub.2 P25) RhB: Rhodamine B

(23) Please refer to FIG. 4A, which shows the results of the photodegradation analysis of the samples 1 to 9, wherein the RhB concentration in each samples is examined while the samples are irradiated with simulated sun light (AM1.5G solar simulator, YAMASGITA DENSO, YSS-E40). In FIG. 4A, the Y-axis represents the apparent reaction rate constant (K.sub.app) to show the photodegradation effect of each sample and comparative samples. As shown in FIG. 4A, the effects of photodegradation of the samples 1 to 5 are better than those of the samples 6 to 9, indicating that the photocatalysts and the active oxide prepared by the present invention perform excellent photodegradation effect toward RhB.

(24) Next, please refer to FIG. 4B, which shows the results of the photodegradation analysis of the samples 1, and 6 to 9, wherein the RhB concentration in each sample is examined while the samples are irradiated with a UV light with wavelength of 352 nm. As shown in FIG. 4B, the effect of photodegradation of sample 1 is better than that of samples 6 to 9.

(25) Please refer to FIG. 4C, which shows the result of the photodegradation analysis of the samples 1 to 5, wherein the RhB concentration in each samples is examined while the samples are irradiated with simulated sun light, which is filtered with a filter to remove the light having wavelength of 422 nm or less. As shown in FIG. 4C, the samples 1 to 5 still perform excellent photodegradation effect toward the light without short wavelength less than 422 nm (including UV light).

(26) Please refer to FIG. 4D, which shows the result of the photodegradation analysis of the sample 1, wherein the RhB concentration therein is examined while this sample is irradiated with different environmental light. As shown in FIG. 4D, the sample 1 still have a certain level of photodegradation effect in the dark room and at light with different wavelengths.

(27) Hence, according to the results shown in FIGS. 4A to 4D, it is proved that the kit for water treatment including the photocatalysts of the present invention performs excellent photodegradation effect in the presence of visible light.

(28) [Effect of the Concentration]

(29) Please refer to FIG. 5A, which shows the result of the photodegradation effect of different ratio of the photocatalyst A and the active oxide to degrade a fixed concentration of pollutants, wherein the RhB concentration in each samples is examined while the samples are irradiated with a simulated sun light. As shown in FIG. 5A, under such concentration of the pollutant, the concentration of the photocatalyst and the active oxide showing the best photodegradation effect is respectively 1.2710.sup.4 M and 2.5 M.

(30) The result shown in FIG. 5B is similar to that shown in FIG. 5A, except that the RhB concentration shown in FIG. 5B is increased to 10 mg/L. As shown in FIG. 5B, under such concentration of the pollutant, the concentration of the photocatalyst and the active oxide showing the best photodegradation effect is respectively 1.2710.sup.4 M and 3.75 M.

(31) [Reusability]

(32) Please refer to FIG. 6, which shows the photodegradation effect of the photocatalyst A to repeatedly degrade RhB. As shown in FIG. 6, there is no significant change in the reaction rate constant using 1.2710.sup.4M of photocatalyst A and 2.5 M of hydrogen peroxide to degrade 1.2 mg/L of RhB after repeatedly performing the photodegradation for 5 times. The reaction rate constant decreases slightly only because the loss of the photocatalyst A due to recovery. Therefore, it is proved that the photocatalyst of the present invention is reusable according to the result shown in FIG. 6.

(33) Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.