CN107597142B - novel Z-shaped acoustic catalyst for degrading antibiotic wastewater and preparation method and application thereof - Google Patents

Abstract

The invention relates to a novel Z-shaped acoustic catalyst for degrading antibiotic wastewater and a preparation method and application thereof. In the invention, a novel Z-shaped nano composite acoustic catalyst Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 is prepared by a simple sol-gel method, hydrothermal method and high-temperature calcination method. The result shows that Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 of Er3+ can form a circulating redox circulating system after the Ni (Fe0.05Ga0.95)2O4 and BiVO4 are compounded, so that the separation of e + and h + is promoted, and the acoustic catalytic degradation capability of the system is remarkably improved. The novel efficient acoustic catalyst can be widely applied to the environmental protection fields of water body purification, wastewater treatment and the like, and has a wide prospect.

Description

Novel Z-shaped acoustic catalyst for degrading antibiotic wastewater and preparation method and application thereof

Technical Field

The invention belongs to the field of acoustic catalysis, and particularly relates to synthesis of an acoustic catalyst Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 with a Z-shaped structure and application thereof in acoustic catalytic degradation of antibiotic wastewater.

background

In recent years, the abuse of antibiotics by human beings generates a large amount of wastewater containing antibiotics, and the antibiotics remained in the wastewater are accumulated in the ecological environment for a long time, so that the wastewater not only has teratogenicity and carcinogenicity, but also can cause the drug resistance of pathogenic microorganisms in the wastewater to be enhanced, and cause serious harm to the ecological balance and human health. Therefore, the treatment of the antibiotic wastewater is urgently needed. The residual antibiotics in the wastewater have the disadvantages of high biotoxicity, large pH fluctuation, deep chromaticity and heavy smell, and bring great difficulty to wastewater treatment. In the face of antibiotics which are difficult to be fully degraded, how to completely treat the antibiotics without harm is a problem which is always puzzled to scientists. The traditional treatment of antibiotic wastewater adopts biological treatment method, physical treatment method, chemical treatment method and the like. However, because the concentration of the common antibiotic wastewater is high, the removal efficiency of the methods is not high, the treatment is not thorough, and secondary pollution is easily caused. And the antibiotic has bacteriostatic effect, and the ideal effect is difficult to obtain by adopting the conventional biological treatment and other technologies. Therefore, it is necessary to find a new processing method. The acoustic catalysis is widely applied to the fields of pollutant treatment and the like due to the advantages of simple and thorough operation and the like.

As a high-level oxidation process, sonocatalysis utilizes the cavitation effect of ultrasound in a solution to generate sonoluminescence and "hot spots". On one hand, at the moment of generating a 'hot spot' by the ultrasonic cavitation effect, the temperature can reach 5000K and the high pressure of 1000 standard atmospheric pressure, so that the water in the solution can be decomposed to generate hydroxyl radicals with strong oxidizing capability. Sonoluminescence, on the other hand, can produce a wide range of light that can excite acoustic catalysts to produce photo-generated electron and hole pairs to degrade antibiotics. The catalyst required by the ideal acoustic catalytic degradation reaction has the characteristics of stability, corrosion resistance, wide light response range, proper bandwidth and the like. Among the numerous acoustic catalysts, NiGa2O4 is one of the most attractive acoustic catalysts due to its corrosion resistance, non-toxicity, and low cost. However, NiGa2O4 has insurmountable disadvantages and shortcomings as an acoustic catalyst. Because of its wide forbidden band width (Eg ═ 3.54eV), it can only be excited by absorbing ultraviolet light (λ <387 nm). Unfortunately, in sonoluminescence, the composition of ultraviolet light is rather low. BiVO4 is another excellent semiconductor catalyst following NiGa2O4, and is used for catalyzing and degrading organic pollutants due to the advantages of no toxicity, stability, small forbidden band width and the like. However, the pure NiGa2O4 and BiVO4 have low efficiency of the acoustic catalytic degradation because of easy recombination of their photo-generated electron and hole pairs. Therefore, it becomes important to invent a catalyst that can completely suppress the photo-generated electron and hole pairs.

Disclosure of Invention

In order to solve the problem that the broadband semiconductor NiGa2O4 cannot effectively utilize ultraviolet light in sonoluminescence, the invention provides a mode of combining an up-conversion luminescent material Er3+: Y3Al5O12 with a semiconductor catalyst. In order to solve the problem of electron and hole recombination, the invention designs and synthesizes a high-efficiency redox cycle recombination center (Fe3+ -NiGa2O4| | | BiVO4) formed by doping Fe3+ into NiGa2O4 and BiVO4, and simultaneously loads noble metal Au. The novel acoustic catalyst with the Z-shaped structure can greatly improve the efficiency of acoustic catalytic degradation.

The technical scheme adopted by the invention is as follows: a novel Z-shaped acoustic catalyst for degrading antibiotic wastewater is characterized in that: er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO 4. Preferably, the molar ratio of Ni (Fe0.05Ga0.95)2O4 to BiVO4 is 1: 1.

A preparation method of a novel Z-shaped acoustic catalyst for degrading antibiotic wastewater comprises the following steps:

1) Dissolving appropriate amounts of Er2O3 and Y2O3 powder in concentrated nitric acid, and magnetically heating and stirring until the solution is colorless and transparent to obtain a rare earth ion solution; weighing Al (NO3) 3.9H 2O according to a certain proportion, dissolving the Al in distilled water, stirring the mixture by using a glass rod at room temperature, slowly adding the mixture into a rare earth ion solution, adding citric acid serving as a chelating agent and a cosolvent according to a molar ratio, heating and stirring the mixture at 50-60 ℃ until the solution is sticky, obtaining a foamed viscose solution, putting the foamed viscose solution into an oven, heating the foamed viscose solution at a constant temperature of 80 ℃ for 36 hours to obtain a foamed sol, heating the foamed sol at 500 ℃ for 50 minutes, then calcining the foamed sol at 1100 ℃ for 2 hours, and cooling the foamed sol to room temperature to obtain Er3+ Y3Al5O12 powder.

2) adding Ga2O3 solid into a nickel nitrate solution, adding a proper amount of Fe (NO3) 3.9H 2O, adjusting the pH of the generated mixed solution to 12 by using sodium hydroxide, then adding Er3+: Y3Al5O12, continuously stirring, transferring the obtained suspension solution into a reaction kettle, reacting for 48 hours at 180 ℃, cooling to room temperature, washing the obtained reactant by using deionized water, then drying for 8 hours at 80 ℃, grinding, roasting for 2 hours in a muffle furnace at 500 ℃, taking out, and grinding again to obtain Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4 nano powder.

3) dissolving nanometer Er3+ Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4 and HAuCl4 solution in ethanol, ultrasonically dispersing for 30 minutes to obtain a suspension, heating the suspension to 60-65 ℃, keeping the temperature constant for 30 minutes, filtering, washing, calcining the separated powder at 350 ℃ for 2 hours, and grinding to obtain Er3+ Y3Al5O12@ Ni (Fe0.05Ga0.95)2O 4/Au.

4) Completely dissolving Bi (NO3) 3.5H 2O in nitric acid to form a solution A, dissolving NH4VO3 in sodium hydroxide to form a solution B, dropwise adding the solution B into the solution A to form a suspension solution, fully stirring, adjusting the pH to 7, continuously stirring for 30min, then transferring into a reaction kettle, reacting at 180 ℃ for 24H to obtain a product, washing with water, drying, and grinding to obtain the BiVO4 nanoparticles.

5) Adding Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4/Au and BiVO4 nano powder into absolute ethyl alcohol, ultrasonically dispersing for 30min to obtain a suspension, heating the suspension to 60-65 ℃, keeping the temperature constant for 30min, filtering, washing, calcining the separated powder at 500 ℃ for 2h, and grinding to obtain Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 nano powder.

the novel Z-shaped acoustic catalyst for degrading the antibiotic wastewater is applied to the acoustic catalytic degradation of the antibiotic wastewater. The method comprises the following steps: adding a novel Z-shaped acoustic catalyst for degrading antibiotic wastewater into the wastewater containing the antibiotic, and irradiating the wastewater at room temperature under 103650Pa, 50W and 40kHz ultrasonic waves for 300 min. Preferably, the antibiotic is a sulfonamide.

The invention relates to a process analysis of a novel Z-type acoustic catalyst Er3+ for degrading antibiotic wastewater, which is characterized in that Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 is used for acoustically catalyzing and degrading sulfanilamide under ultrasonic irradiation: it is known that the bandwidth of NiGa2O4 is 3.5eV, and when visible light generated by sonoluminescence directly irradiates the surface, it cannot excite the NiGa2O4 particles to generate electron-hole pairs, and when visible light irradiates Er3+: Y3Al5O12, since Er3+: Y3Al5O12 can be excited to higher energy level step by step under visible light (low energy light) irradiation, and then these photons jump back to ground state to emit ultraviolet light (high energy light), these ultraviolet lights can effectively excite the NiGa2O4 particles around Er3+: Y3Al5O12 to generate photo-generated electron-hole pairs. In order to provide ultraviolet light to NiGa2O4 to the maximum extent and greatly improve the acoustic catalytic efficiency, the invention utilizes broadband spectrum to absorb the up-conversion ultraviolet luminescent material Er3+: Y3Al5O12, and converts infrared light and visible light generated in the sonoluminescence to the ultraviolet light to the maximum extent. Because the electron-hole pairs generated after the NiGa2O4 and the BiVO4 are excited by light are easy to recombine and lose catalytic activity, in order to thoroughly separate photogenerated e-and h +, the catalytic activity is further improved, and Fe3+ doped into the NiGa2O4 and V5+ in the BiVO4 form a supposed recombination cycle center. In this cycling system V5+ was reduced to V4+ by e-on the conduction band of BiVO4 and Fe3+ was oxidized to Fe4+ by h + on the valence band of NiGa2O 4. In addition, Fe4+ was sufficient to oxidize V4+ at the center of the putative recombination cycle formed by BiVO4 conduction band and NiGa2O4 valence band, thereby regenerating Fe3+ and V5+ repeating the previous redox reaction. Notably, e-on the conduction band of NiGa2O4 and h + on the valence band of BiVO4 are completely separated. On the one hand, the cavity generated by the valence band of BiVO4 can directly decompose sulfanilamide on the surface. On the other hand, the e-generated on the conduction band of NiGa2O4 reacts with oxygen dissolved in aqueous solution to generate superoxide radical, and the superoxide radical generates hydroxyl radical through a series of chemical reactions, and the hydroxyl radical has strong oxidizability and can oxidize sulfanilamide. The invention effectively avoids the recombination of photo-generated electrons and holes by utilizing a designed supposed compound circulating redox system, thereby improving the degradation efficiency of the catalyst.

The invention has the beneficial effects that:

The Er3+ Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 nano-scale acoustic catalyst prepared by the invention has stable property, high temperature resistance and acid and alkali corrosion resistance, and compared with the pure NiGa2O4 and BiVO4, the efficiency of degrading antibiotics under ultrasonic irradiation of the catalyst is greatly improved. Compared with the traditional Ta2O5-TiO2 photocatalyst, the Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 nano-scale acoustic catalyst not only has the advantages of traditional acoustic catalytic degradation, but also has the most remarkable attention due to the addition of the up-conversion luminescent material Er3+: Y3Al5O12, the doping of Fe3+ ions and the use of Au as a conductive channel and a promoter. The addition of the up-conversion luminescent material Er3+: Y3Al5O12 enables the Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 nano-scale acoustic catalyst to absorb ultraviolet light and convert the absorbed infrared light and visible light into ultraviolet light. The doping of Fe3+ ions can ensure that photo-generated electron and hole pairs of the photo-excited catalyst can be separated more thoroughly, and the efficiency of degrading antibiotic wastewater by the acoustic catalysis of the acoustic catalyst is greatly improved.

Drawings

FIG. 1a is an X-ray powder diffraction (XRD) pattern of Er3+: Y3Al5O 12.

FIG. 1b is an X-ray powder diffraction (XRD) pattern of NiGa2O 4.

FIG. 1b-1 is an X-ray powder diffraction (XRD) pattern of Ni (Fe0.05Ga0.95)2O 4.

Figure 1c is an X-ray powder diffraction (XRD) pattern of BiVO 4.

FIG. 1d is the X-ray powder diffraction (XRD) pattern of Er3+: Y3Al5O12@ NiGa2O 4.

FIG. 1d-1 is an X-ray powder diffraction (XRD) pattern of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O 4.

FIG. 1e is the X-ray powder diffraction (XRD) pattern of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-BiVO 4.

FIG. 1f is an X-ray powder diffraction (XRD) pattern of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO 4.

FIG. 2a is a Transmission Electron Microscope (TEM) image (100nm) of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO 4.

FIG. 2b is a Transmission Electron Microscope (TEM) image (20nm) of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO 4.

FIG. 2c is a Transmission Electron Microscope (TEM) image (10nm) of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO 4.

FIG. 3a is a graph of the Infrared (IR) spectrum of Er3+: Y3Al5O 12.

FIG. 3b is an Infrared (IR) spectrum of NiGa2O 4.

Figure 3c is an Infrared (IR) spectrum of BiVO 4.

FIG. 3d is an Infrared (IR) spectrum of Ni (Fe0.05Ga0.95)2O 4.

FIG. 3e is an Infrared (IR) spectrum of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O 4. .

FIG. 3f is a graph of the Infrared (IR) spectrum of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO 4.

FIG. 4a is a graph of the UV absorption spectra of a sulfonamide solution in the presence of an acoustic catalyst Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 for different periods of time.

Figure 4b is a graph comparing the degradation effect on sulfonamide solution in the presence and absence of catalyst.

Figure 5a is a graph of the effect of different capture agents on the sonocatalytic degradation of sulfonamide solutions.

FIG. 5b is a graph showing the effect of the number of times of use on the activity of an acoustic catalyst Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 for the acoustic catalytic degradation of a sulfonamide solution.

FIG. 6 is a mechanism diagram of pollutant degradation of Er3+ Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO 4.

Detailed Description

EXAMPLE 1 novel Z-type Acoustic catalyst Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4

(I) preparation method

1. Preparation of Er3+: Y3Al5O12 nanopowder

2.7281g of Er2O3(99.99 percent) and 0.0464g Y2O3(99.99 percent) powder are dissolved in concentrated nitric acid (65.00 percent) and stirred by magnetic heating until the solution is colorless and transparent, thus obtaining the rare earth ion solution. 12.6208g of Al (NO3) 3.9H 2O (99.99%) were weighed out and dissolved in distilled water, stirred with a glass rod at room temperature and slowly added to the rare earth ion solution. Using citric acid as a chelating agent and a cosolvent, wherein the molar ratio of the citric acid: weighing citric acid, dissolving in distilled water, adding into the above mixed solution, heating at 50-60 deg.C, stirring, and stopping when the solution is viscous. No precipitate was formed during this process, and a foamed viscose solution was finally obtained. And (3) putting the foaming viscose solution into an oven, keeping the temperature of the foaming viscose solution constant at 80 ℃, and heating the foaming viscose solution for 36 hours. No precipitate is formed during the drying process until the solvent is evaporated to dryness, and finally a foamed sol is obtained. The sol obtained was heated at 500 ℃ for 50min and then calcined at 1100 ℃ for 2 h. Finally, the sintered mass was removed from the high temperature furnace and cooled to room temperature in air to give a powder of Er3+: Y3Al5O 12.

2. Preparation of Ni (Fe0.05Ga0.95)2O4 nanopowder

Adding 10mmol of Ga2O3 solid into 10mmol of nickel nitrate solution, adding 0.0007mmol of Fe (NO3) 3.9H 2O into the mixed solution, adjusting the pH of the generated mixed solution to 12 with 1mol/L of sodium hydroxide (stirring for 30min while adjusting), transferring the obtained suspension solution into a reaction kettle at 180 ℃ for 48H, cooling to room temperature to obtain light blue precipitate, washing with deionized water for several times, drying the obtained precipitate at 80 ℃ for 8H to obtain Ni (Fe0.05Ga0.95)2O4 powder, grinding the powder, roasting for 2H in a muffle furnace at 500 ℃, taking out, and grinding to obtain Ni (Fe0.05Ga0.95)2O4 nano particles.

3. Preparation of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4 nanopowder

10mmol Ga2O3 solid is added to 10mmol nickel nitrate solution, 0.0007mmol Fe (NO3) 3.9H 2O is added, the pH of the resulting mixture is adjusted to 12 with 1mol/L sodium hydroxide (stirring for 30min while adjusting), then 4.30mmol Er3+: Y3Al5O12 is added and stirring is continued for 20 min. Transferring the obtained suspension solution into a reaction kettle, reacting at 180 ℃ for 48h, cooling to room temperature to obtain light blue precipitate, and washing with deionized water for several times. Drying the obtained precipitate at 80 ℃ for 8h, grinding, roasting in a muffle furnace at 500 ℃ for 2h, taking out, and grinding to obtain Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4 nanoparticles.

4. Preparation of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4/Au nanopowder

Dissolving 10mmol of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4 nano powder and 7.8mL of HAuCl4 solution in 200mL of ethanol, fully dispersing for 30 minutes by using ultrasound (40kHz, and the output power of the ultrasound is 50W) to obtain suspension, heating the suspension to 60-65 ℃, keeping the temperature constant for 30 minutes, filtering, washing, calcining the separated powder at 350 ℃ for 2 hours, and grinding to obtain Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O 4/Au.

5. Preparation of BiVO4 nanopowder

5mmol of Bi (NO3) 3.5H 2O was completely dissolved in nitric acid to form a solution A, and 5mmol of NH4VO3 was dissolved in sodium hydroxide to form a solution B. And dropwise adding the solution B into the solution A to form a yellow suspension solution, fully stirring, adjusting the pH value to 7 by using sodium hydroxide, continuously stirring for 30min, then transferring into a reaction kettle, washing for several times by using clear water after 24h at 180 ℃ to obtain a product, finally drying, taking out, and grinding to obtain the BiVO4 nano particles.

6. Preparation of Er3+ (Y3 Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO 4) nanopowder

Adding 10mmol of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4/Au and 10mmol of BiVO4 nano powder into absolute ethyl alcohol, performing ultrasonic dispersion for 30min to obtain a suspension, heating the suspension to 65 ℃, keeping the temperature constant for 30min, filtering, washing, calcining the separated powder at 500 ℃ for 2h, and grinding to obtain Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 nano powder.

(II) detection

1) The compositions and structures of the prepared samples were characterized by XRD, with FIGS. 1 a-1 f being X-ray powder diffraction (XRD) patterns of Er3+: Y3Al5O12, NiGa2O4, Ni (Fe0.05Ga0.95)2O4, BiVO4, Er3+: Y3Al5O12@ NiGa2O4, Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4, Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-BiVO4 and Er3+: Y3Al5O12@ Ni (Fe0.050.95) 2O4-Au-BiVO 4.

As shown in fig. 1a, Er3+: Y3Al5O12 shows some sharp absorption peaks at 2 θ -18.10 ° (211), 27.76 ° (321), 29.78 ° (400), 33.38 ° (420), 35.07 ° (332), 36.68 ° (422), 41.14 ° (521), 46.53 ° (532), 52.74 ° (444), 55.06 ° (640), 57.32 ° (642) and 61.83 ° (800), which are in perfect agreement with the standard card JCPDS card 33-0040 of Y3Al5O 12. It demonstrated that Er3+ Y3Al5O12 had been successfully prepared and that Er3+ had entered the lattice of Y3Al5O12 in place of Y3 +.

As shown in fig. 1b, the prepared sample shows sharp absorption peaks at 2 θ of 18.6 °, 30.6 °, 36.0 °, 37.7 °, 43.8 °, 54.4 °, 58.0 ° and 63.7 ° and corresponds one-to-one to crystal planes (110), (220), (311), (222), (400), (422), (511) and (440) of the cubic spinel structure NiGa2O4 standard card JCPDS card 14-0117. This indicates that NiGa2O4 of a cubic spinel structure was prepared.

It can be observed from fig. 1b-1 that the characteristic peak at 36.0 ° to 37.7 ° of 2 θ is slightly shifted, probably due to Fe3+ substituting a part of Ga3+ into the lattice of NiGa2O 4.

As shown in FIG. 1c, BiVO4 powder was prepared in good agreement with the standard card JCPDS card 14-0688. The main absorption peaks occur at 15.14 °, 18.67 °, 28.58 °, 30.55 °, 34.49 °, 35.22 °, 40.04 °, 46.71 °, 47.31 ° and 54.58 °, corresponding to the crystal planes (110), (011), (121), (040), (200), (002), (112), (240), (042) and (161).

In FIG. 1d and FIG. d-1, it was found that in addition to the standard peak of NiGa2O4, a characteristic peak of Er3+: Y3Al5O12 also appeared, indicating that Er3+: Y3Al5O12@ NiGa2O4 has been successfully prepared. Furthermore, from fig. 1d-1, it can be noted that there is a slight shift in the absorption peaks from 2 θ ═ 36.0 ° to 2 θ ═ 37.7 °, which can prove that Er3+: Y3Al5O12@ Ni (fe0.05ga0.95)2O4 was also successfully prepared.

In FIGS. 1e and 1f, it can be found that the characteristic peak of BiVO4 can be clearly found in addition to the characteristic peak of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O 4. Further in fig. 1f, two absorption peaks at 38.2 ° and 44.4 ° were observed, which correspond to the standard card JCPDS65-2870 for Au particles, with (111) and (200) crystal planes, respectively. The presence of Au particles can be further confirmed by EDX.

2) A Transmission Electron Microscope (TEM) was used to observe the detailed structural morphology of the samples, and FIG. 2 a-FIG. 2c are the Transmission Electron Microscope (TEM) picture analyses of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO 4.

FIGS. 2 a-2 c show TEM images of the coated complex Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 at different magnification ratios, where the corresponding unit ratio lengths are 100nm, 20nm and 10nm, respectively. From FIG. 2a it can be seen that some of the platelet-shaped particles are small-sized BiVO4, and the other large-sized particles are Ni (Fe0.05Ga0.95)2O4 coated with a light conversion agent (Er3+: Y3Al5O 12). Some tiny black particles can be observed to be dispersed around the large particles, and it can be proved that Au particles have been deposited on the surface of Ni (Fe0.05Ga0.95)2O 4. As shown in fig. 2b, the cladding structure was found to be clearer at a scale of 20nm, from which it was observed that Er3+: Y3Al5O12 had been cladded inside Ni (fe0.05ga0.95)2O4, except that some Au nanoparticles were embedded between Ni (fe0.05ga0.95)2O4 and BiVO4, and others were randomly dispersed to the surface of Ni (fe0.05ga0.95)2O 4. When the unit scale is further enlarged to 10nm, as shown in fig. 2c, many clear lattice fringes are exhibited. By calculating the lattice fringe spacing and comparing with XRD data, the crystal planes of the prepared acoustic catalyst can be determined. They are clearly marked in fig. 2c, as shown in fig. 2c, Er3+: Y3Al5O12(d 0.293nm (221)), Au (d 0.230nm (111)), Ni (fe0.05ga0.95)2O4(d 0.286nm (202)), and BiVO4(d 0.315nm (121)). In addition, TEM results showed that Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 formed a core-shell coated structure centered on Er3+: Y3Al5O 12.

3) FIGS. 3 a-3 f are Infrared (IR) spectrum photographic analyses of Er3+: Y3Al5O12, NiGa2O4, BiVO4, Ni (Fe0.05Ga0.95)2O4, Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4 and Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO 4.

FIG. 3a presents the infrared spectrum of Er3+: Y3Al5O 12. According to the early reports at 799.3cm-1 and 461.6cm-1 are the vibrations between metal and oxygen (Y-O and Al-O). Looking at the infrared spectra of fig. 3b and 3d, two strong absorption peaks can be found. It was concluded that these absorption peaks are formed by two sublattices, a single-phase spinel structure with tetrahedral and octahedral sites, respectively. The absorption band at 452.5nm is mainly due to tensile vibration of the metal oxygen at the tetrahedral sites; while the absorption band at 636.2nm is largely due to the octahedral complex, which is in good agreement with the characteristic absorption of NiGa2O 4. It can also be noted from FIG. 3d that the absorption peak appearing at 959.44cm may be Fe-O stretching vibration, again demonstrating that Fe was successfully doped into NiGa2O 4. From the infrared spectrum of BiVO4 in fig. 3c, it can be observed that the absorption peak at 3439.4nm may belong to the stretching vibration of the adsorbed water molecules; meanwhile, the absorption peak at 1636.5nm is likely to be caused by deformation vibration of-OH groups of adsorbed water molecules. In addition, the absorption peak at 742nm is likely due to VO 43-asymmetric stretching vibration. As can be seen from FIGS. 3e and 3f, characteristic absorption peaks of Er3+: Y3Al5O12 and Ni (Fe0.05Ga0.95)2O4 appear at 799.3cm-1, 461.6cm-1, 452.5cm-1 and 632.2 cm-1. As further seen in FIG. 3f, in addition to the characteristic absorption peaks for Er3+: Y3Al5O12 and Ni (Fe0.05Ga0.95)2O4, the characteristic absorption for BiVO4 occurred at 745.23cm-1, indicating that the coated hybrid catalyst Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 was successfully prepared.

Example 2 application of novel Z-type Acoustic catalyst Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 in the Acoustic catalytic degradation of sulfonamides

(I) ultraviolet absorption spectrogram of sulfanilamide solution in the presence of acoustic catalyst Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 for different time periods.

The experimental conditions are as follows: 200mg Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 and 200mL10.0mg/L of aqueous Sulfanilamide (SA). Irradiating with 50W, 40KHz ultrasonic wave at 25 deg.C and 101325Pa for 300min at 50min interval.

The results are shown in FIG. 4 a. Generally, when a compound has a double bond or a conjugated double bond, pi → pi electron transfer may occur under excitation of matched ultraviolet light. At the same time, n → pi electron transfer may occur when some heteroatoms with lone electron pairs are present. From the UV absorption spectrum of FIG. 4a, it can be seen that an absorption band occurs at 257nm in the UV region, which coincides with the pi → pi and n → pi electron transfer of the benzene ring and nitrogen-containing bonds. These absorption bands occurring in the ultraviolet region can be used to evaluate the remaining sulfonamide molecules in solution and to calculate their degradation rate. When the ultrasonic irradiation time reaches 300 minutes, the maximum degradation rate reaches 95.64% at 257 nm. The results show that the absorption peak at 257nm almost completely disappeared when the ultrasound was irradiated for 300 minutes, indicating that the sulfonamide molecule was completely degraded.

(II) influence of the presence or absence of a catalyst on degradation of the sulfonamide solution.

The experimental conditions are as follows: eight conical flasks were labeled (a) US, (b) US/BiVO4, (c) US/NiGa2O4, (d) US/Ni (Fe0.05Ga0.95)2O4, (e) US/Er3+: Y3Al5O12@ NiGa2O4, (f) US/Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4, (g) US/Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-BiVO4 and (h) US/Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4, each flask having 200mg of the corresponding US catalyst and 200mL10.0mg of sulfanilamide aqueous Solution (SA), without any ultrasonic irradiation, (a) added. And (3) irradiating the mixture for 300min by using 50W and 40KHz ultrasonic waves at the temperature of 25 ℃ and the pressure of 101325Pa, and recording the degradation effect.

As shown in fig. 4b, (a): US corresponds to a pure ultrasound irradiation without any catalyst added, and the degradation rate after 300min is only 38.63%. However, when the catalyst was added, their degradation rate was increased. The improvement is particularly remarkable when BiVO4 is added, which is probably because BiVO4 can broaden the photoresponse range as a narrow-band semiconductor. The gradual increase in degradation rate is seen in FIG. 4b (c-f), indicating that the presence of the upconverting light-emitting agent (Er3+: Y3Al5O12) and Fe3+ plays an important role. For (g), its degradation rate is the highest probably because Ni (Fe0.05Ga0.95)2O4 and BiVO4 form a Z-type system, and the conduction rate of electrons is greatly improved due to the presence of Au as a conductive channel. For (h), the degradation rate was maximal, reaching 95.64%.

(III) influence of different capture agents on acoustocatalytic degradation of sulfanilamide solution

To further demonstrate the reaction mechanism of the sonocatalytic degradation of Sulfonamide (SA), it was necessary to identify whether the reaction was dominated by hydroxyl radical (. OH) degradation or by hole (h +) degradation.

The experimental conditions are as follows: into five Erlenmeyer flasks, 200mg of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 and 200mL of 10.0mg/L aqueous Sulfanilamide (SA) solution were added, respectively. Four capture agents, DMSO, t-butanol (t-BuOH), EDTA and oxalic acid, were added to four flasks, respectively, and a blank experiment was also performed by ultrasonic irradiation at 25 deg.C and 101325Pa at 50W and 40KHz for 300 min. In the past, DMSO and t-BuOH have been reported by many researchers to be effective in trapping OH in solution. And it is well known that EDTA and oxalic acid have the property of trapping holes.

In fig. 5a, the experimental results show that the degradation rate of Sulfonamide (SA) is close to 96% at 300min without addition of any capture agent. After the addition of these trapping agents, the rates of the acoustic catalytic degradation of Sulfonamide (SA) were all significantly reduced compared to the blank, which decreased to 54.60%, 48.21%, 24.88% and 30.98%, respectively. Of particular note is the most pronounced decrease in the rate of sonocatalytic degradation of Sulfanilamide (SA) in systems incorporating a hole trap, probably because most of the sonocatalytically degraded Sulfanilamide (SA) is predominantly oxidized by the hole (h +) in the valence band of BiVO4, since BiVO4 has a higher positive potential. DMSO and t-butanol (t-BuOH) as a hole (h +) trapping agent react with the hole (h +) to generate a substance with low reactivity, thereby preventing the acoustic catalytic degradation reaction from proceeding. In addition, hydroxyl radical (. OH) oxidation also makes some contribution to the sonocatalytic degradation of Sulfonamide (SA) as a secondary effect. It can therefore be concluded that the sonocatalytic degradation of Sulphonamides (SA) is carried out by a combination of a hole (h +) reaction and a hydroxyl radical (. OH) reaction, but with hole oxidation predominating.

(IV) the influence of the use times on the degrading sulfanilamide performance of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4

The experimental conditions are as follows: 1.60g of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 powder was added into eight erlenmeyer flasks, and 200mg of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 and 200mL of 10.0mg/L aqueous Sulfanilamide (SA) solution were put into each erlenmeyer flask. And (3) irradiating the mixture for 300min by using 50W and 40KHz ultrasonic waves at the temperature of 25 ℃ and the pressure of 101325Pa, and recording the degradation effect. And recovering the solution, filtering and collecting the catalyst for later use. The catalyst extracted for the first time is dried and calcined, 1.20g of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 powder is taken out and added into six conical flasks respectively, and 200mg of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 and 200mL of 10.0mg/L Sulfanilamide (SA) aqueous solution are put into each conical flask respectively. And (3) irradiating the mixture for 300min by using 50W and 40KHz ultrasonic waves at the temperature of 25 ℃ and the pressure of 101325Pa, and recording the degradation effect. And recovering the solution, filtering and collecting the catalyst for later use. Repeat the above steps 4 times. The results are shown in FIG. 5 b.

As can be seen from fig. 5b, the degradation rate of Sulfonamide (SA) decreased slightly with increasing number of repetitions, and was generally smooth, indicating that the catalyst was stable and reusable.

The principle of degrading sulfanilamide by Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 is as follows: the NiGa2O4 has a bandwidth of 3.54eV, wherein the valence band is 1.23eV and the conduction band is-2.31 eV. BiVO4 has a bandwidth of 2.412eV, a valence band of +2.741eV, and a conduction band of 0.329 eV. Because the valence band potential of NiGa2O4 is close to the conduction band potential of BiVO4, an ideal Z-type photocatalytic system can be formed, and photo-generated electron and hole pairs can be efficiently transferred. In order to more thoroughly transfer photogenerated electron and hole pairs, Fe3+ is doped into NiGa2O4 to form a supposed redox recombination center with BiVO 4. In the sonocatalytic degradation reaction, V5+ is reduced to V4+ by BiVO4 conduction band electrons, and Fe3+ is oxidized to Fe4+ by h + itself on the NiGa2O4 valence band. In addition, Fe4+ was sufficient to oxidize V4+ at the putative recombination center formed at the conduction band of BiVO4 and the valence band of NiGa2O4, thereby regenerating Fe3+ and V5+ to repeat the previous redox reaction. That is, the sonocatalytic degradation reaction forms a redox cycling system of Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO 4. It is worth noting that the e-on the conduction band of NiGa2O4 and the hole on the valence band of BiVO4 are completely separated, and the e-is rapidly transferred from the conduction band of NiGa2O4 to the surface of the catalyst Au, reacts with oxygen molecules (O2) dissolved in aqueous solution and generates superoxide radical negative ions (. O2-) which become hydroxyl radical (. OH) through a series of chemical reactions. These hydroxyl radicals (. OH) have a strong oxidizing power and are capable of degrading the surrounding organic pollutants, producing volatile by-products or carbon dioxide, water and mineral acids by mineralization. On the one hand, the holes generated in the Valence Band (VB) of BiVO4 can directly decompose organic pollutants on the surface of its crystal particles until they are completely decomposed. On the other hand, the generated water (H2O) molecules absorbed by the oxidation of holes generate hydroxyl radicals (& OH) on the surfaces of BiVO4 crystal particles, and indirectly degrade or destroy the structure of organic contaminants in an aqueous solution.

Claims (5)

1. A Z-shaped acoustic catalyst for degrading antibiotic wastewater is characterized in that: the Z-shaped acoustic catalyst for degrading the antibiotic wastewater is as follows: er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO 4; the molar ratio of Ni (Fe0.05Ga0.95)2O4 to BiVO4 is 1:1, and the preparation method comprises the following steps:

1) Adding Ga2O3 solid into a nickel nitrate solution, adding a proper amount of Fe (NO3) 3.9H 2O, adjusting the pH of the generated mixed solution to 12, adding Er3+: Y3Al5O12, continuously stirring, transferring the obtained suspension solution into a reaction kettle, reacting for 48 hours at 180 ℃, cooling to room temperature, cleaning the obtained reactant with deionized water, drying for 8 hours at 80 ℃, grinding, roasting for 2 hours in a muffle furnace at 500 ℃, taking out, and grinding again to obtain Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4 nano powder;

2) Dissolving nanometer Er3+ Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4 and HAuCl4 solution in ethanol, ultrasonically dispersing for 30 minutes to obtain a suspension, heating the suspension to 60-65 ℃, keeping the temperature constant for 30 minutes, filtering, washing, calcining the separated powder at 350 ℃ for 2 hours, and grinding to obtain Er3+ Y3Al5O12@ Ni (Fe0.05Ga0.95)2O 4/Au;

3) Completely dissolving Bi (NO3) 3.5H 2O in nitric acid to form a solution A, dissolving NH4VO3 in sodium hydroxide to form a solution B, dropwise adding the solution B into the solution A to form a suspension solution, fully stirring, adjusting the pH =7, continuously stirring for 30min, then transferring into a reaction kettle, reacting at 180 ℃, reacting for 24H to obtain a product, washing with water, drying, and grinding to obtain BiVO4 nanoparticles;

4) adding Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4/Au and BiVO4 nano powder into absolute ethyl alcohol, ultrasonically dispersing for 30min to obtain a suspension, heating the suspension to 60-65 ℃, keeping the temperature constant for 30min, filtering, washing, calcining the separated powder at 500 ℃ for 2h, and grinding to obtain Er3+: Y3Al5O12@ Ni (Fe0.05Ga0.95)2O4-Au-BiVO4 nano powder.

2. The Z-shaped acoustic catalyst for degrading antibiotic wastewater as claimed in claim 1, wherein the preparation method of Er3+ Y3Al5O12 comprises the following steps: dissolving appropriate amounts of Er2O3 and Y2O3 powder in concentrated nitric acid, and magnetically heating and stirring until the solution is colorless and transparent to obtain a rare earth ion solution; weighing Al (NO3) 3.9H 2O according to a proportion, dissolving the Al (NO3) 3.9H 2O in distilled water, stirring the mixture by using a glass rod at room temperature, slowly adding the mixture into a rare earth ion solution, adding citric acid serving as a chelating agent and a cosolvent according to a mol ratio, heating and stirring the mixture at 50-60 ℃, stopping heating the mixture when the solution is sticky to obtain a foamed viscose solution, putting the foamed viscose solution into an oven to heat for 36 hours at 80 ℃ to obtain foamed sol, heating the foamed sol for 50 minutes at 500 ℃, then calcining the foamed sol for 2 hours at 1100 ℃, and cooling the calcined sol to room temperature to obtain Er3+ Y3Al5O12 powder.

3. Use of a Z-shaped acoustic catalyst for degrading antibiotic wastewater according to claim 1 or 2 in the acoustic catalytic degradation of antibiotic wastewater.

4. The use according to claim 3, characterized in that the method is: adding a Z-shaped acoustic catalyst for degrading antibiotic wastewater into the wastewater containing the antibiotic, and irradiating the wastewater at room temperature under 103650Pa, 50W and 40kHz ultrasonic waves for 300 min.

5. Use according to claim 3 or 4, characterized in that: the antibiotic is sulfanilamide.