UV/TiO2 photodegradation of metronidazole,ciprofloxacin and sulfamethoxazole in aqueous solution: An optimization and kinetic study

Emerging pharmaceutical ingredients (APIs) like sulfamethoxazole (SMX), metronidazole (MNZ) and ciprofloxacin (CIP) are biopersistent and toxic to the environment and public health. In this study, UV/TiO₂ photodegradation was applied in the degradation of SMX, MNZ and CIP individually and in a mixture. For a 5 mg/L SMX solution, about 97% of SMX was degraded within 360 min, which was reduced to 80% for 80 mg/L of SMX solution at the same TiO₂ dosage and photodegradation time. The maximum removals of MNZ and CIP as individual components were 100% and 89%, respectively at 600 min of photodegradation reaction time. For binary mixtures, the highest removal (100%) was achieved for MNZ and CIP ([MNZ] = [CIP] = 40 mg/L) mixture at 120 min whereas the degradations were 97% and 96% for SMX and MNZ, and SMX and CIP binary mixtures, respectively, even after 600 min of experimental time at the same concentrations. For tertiary mixture, the maximum degradation 99% was observed for (SMX = CIP] = 20 mg/L and [MNZ] = [40 mg/L) at 600 min. The observed reaction rate was 0.01085 min^?1 when SMX concentration was 5 mg/L, which decreased to 0.00501 min^?1 for SMX concentration of 80 mg/L, indicating decreasing of reaction rate at higher concentration. The results indicate that the UV/TiO₂ process is promising to apply for the treatment of pharmaceutical wastewaters.     

Insights into the electrochemical degradation of sulfamethoxazole and its metabolite by Ti/SnO2-Sb/Er-PbO2 anode

Electrochemical degradation of sulfamethoxazole (SMX) and its metabolite acetyl-sulfamethoxazole (Ac-SMX) by Ti/SnO₂-Sb/Er-PbO₂ were investigated. Results indicated that the electrochemical degradation of SMX and Ac-SMX followed pseudo-first-order kinetics. The rate constants of SMX and Ac-SMX were 0.268 and 0.072 min^-1 at optimal current density of 10 and 14 mA/cm², respectively. Transformation products of SMX and Ac-SMX were identified and the possible degradation pathways, including the cleavage of S-N bond, opening ring of isoxazole and nitration of amino group, were proposed. Total organic carbon removal of SMX was nearly 63.2% after 3 h electrochemical degradation. 22.4% nitrogen of SMX was transformed to NO₃^-, and 98.8% sulfur of SMX was released as SO₄^2-. According to quantitative structure-activity relationship model, toxicities of SMX and Ac-SMX to aquatic organisms significantly decreased after electrochemical degradation. Electric energy consumption for 90% SMX and Ac-SMX degradation was determined to be 0.58-8.97 and 6.88-44.19 Wh/L at different experimental conditions, respectively. Compared with parent compound SMX, the metabolite Ac-SMX is more refractory and toxic, which emphasizes the importance of taking its metabolites into account when investigating the disposal of pharmaceuticals from wastewater.     

Photocatalytic degradation of organic dyes by Er<Superscript>3+</Superscript>: YAlO<Subscript>3</Subscript>/Co- and Fe-doped ZnO coated composites under solar irradiation

In this work, the Er³⁺: YAlO₃/Co- and Fe-doped ZnO coated composites were prepared by the sol-gel method. Then, they were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX). Photo-degradation of azo fuchsine (AF) as a model dye under solar light irradiation was studied to evaluate the photocatalytic activity of the Er³⁺: YAlO₃/Co- and Fe-doped ZnO coated composites. It was found that the photocatalytic activity of Co- and Fe-doped ZnO composites can be obviously enhanced by upconversion luminescence agent (Er³⁺: YAlO₃). Besides, the photocatalytic activity of Er³⁺: YAlO₃/Fe-doped ZnO is better than that of Er³⁺: YAlO₃/Co-doped ZnO. The influence of experiment conditions, such as the concentration of Er³⁺: YAlO₃, heat-treatment temperature and time on the photocatalytic activity of the Er³⁺: YAlO₃/Co- and Fe-doped ZnO coated composites was studied. In addition, the effects of solar light irradiation time, dye initial concentration, Er³⁺: YAlO₃/Co- and Fe-doped ZnO amount on the photocatalytic degradation of azo fuchsine in aqueous solution were investigated in detail. Simultaneously, some other organic dyes, such as Methyl Orange (MO), Rhodamine B (RM-B), Acid Red B (AR-B), Congo Red (CR), and Methyl Blue (MB) were also studied. The possible excitation principle of Er³⁺: YAlO₃/Co- and Fe-doped ZnO coated composites under solar light irradiation and the photocatalytic degradation mechanism of organic dyes were discussed.     

Statistical modeling of <Emphasis Type="Italic">p</Emphasis>-nitrophenol degradation using a response surface methodology (RSM) over nano zero-valent iron-modified Degussa P25-TiO<Subscript>2</Subscript>/ZnO photocatalyst with persulfate

Zero-valent iron-modified Degussa P25-TiO₂/ZnO nanocomposites (denoted as P25/Fe⁰/ZnO) were designed and prepared via Fe⁰ impregnation of P25-TiO₂/ZnO and then were employed in the visible-light photocatalytic degradation of p-nitrophenol (PNP) in the presence of [K₂S₂O₈]. Central composite design was applied for response surface modeling (RSM) to understand the influence of selected factors (pH, [Fe⁰] wt% and [K₂S₂O₈] concentration) on the degradation of PNP and to determine the interaction between the factors. The maximal PNP degradation efficiency (86.9%) was obtained with P25/1.5 wt% Fe⁰/ZnO at 3 mg/L of [K₂S₂O₈] concentration and pH 7.5. In addition, the RSM showed a satisfactory correlation between the experimental and predicted values of PNP degradation. The P25/Fe⁰/ZnO photocatalyst performance was also examined degrading methyl orange and phenol and high degradation efficiency, 82 and 99%, was achieved, respectively. The structure, morphology, light absorption and photocatalytic properties of as-prepared P25/Fe⁰/ZnO were studied using TEM, BET, XRD, FTIR and DRS.     

Unraveling pharmaceuticals removal in a sulfur-driven autotrophic denitrification process: Performance,kinetics and mechanisms

The removal of eight typical pharmaceuticals (PhACs) (i.e., ibuprofen (IBU), ketoprofen (KET), diclofenac (DIC), sulfadiazine (SD), sulfamethoxazole (SMX), trimethoprim (TMP), ciprofloxacin (CIP) and enoxacin (ENO)) in sulfur-driven autotrophic denitrification (SdAD) process were firstly investigated via long-term operation of bioreactor coupled with batch tests. The results indicated that IBU and KET can be effectively removed (removal efficiency > 50%) compared to other six PhACs in SdAD bioreactor. Biodegradation was the primary removal route for IBU and KET with the specific biodegradation rates of 5.3±0.7～18.1±1.8 µg g^?1-VSS d^?1 at initial concentrations of 25-200 µg/L. The biotransformation intermediates of IBU and KET were examined, and the results indicated that IBU was biotransformed to three intermediates via hydroxylation and carboxylation. KET biotransformation could be initiated from the reduction of the keto group following with a series of oxidation/reduction reactions, and five intermediates of KET were observed in this study. The microbial community composition in the system was markedly shifted when long-term exposure to PhACs. However, the functional microbes (e.g., genus Thiobacillus) showed high tolerance to PhACs, resulting in the high efficiency for PhACs, N and S removal during long-term SdAD reactor operation. The findings provide better insight into PhACs removal in SdAD process, especially IBU and KET, and open up an innovative opportunity for the treatment of PhACs-laden wastewater using sulfur-mediated biological process.     

MOF-808/BiOCl复合材料的制备及其光催化性能

将高稳定性的MOF-808与BiOCl结合,采用简便的水热法制备出新型MOF-808/BiOCl复合异质结材料。以环丙沙星(CIP)为污染物,探究复合材料MOF-808/BiOCl对CIP的光催化性能。发现含有10% MOF-808的复合材料(MOF-808/BiOCl-10%)表现出最佳的光催化活性。在紫外光照射20 min内,MOF-808/BiOCl-10%对CIP的光催化降解效率高达94.7%。通过X射线粉末衍射、扫描电镜、红外光谱、荧光光谱、紫外可见漫反射光谱、光电流、电化学阻抗等表征技术来考察材料的物相组成、形貌以及光电化学性质。紫外可见漫反射光谱的结果表明,MOF-808/BiOCl-10%材料光吸收范围得到提高。同时进行了自由基捕获实验。基于以上实验数据,提出了MOF-808/BiOCl复合材料可能的光催化机理。     

Preparation of Er3+:YAlO3/Fe-doped ZnO composite and investigation on solar light photocatalytic degradation of organic dyes

The Er³⁺:YAlO₃/Fe-doped ZnO composite, a new photocatalyst which could effectively utilize visible light, was prepared. In succession, the Er³⁺:YAlO₃/Fe-doped ZnO was characterized by XRD and SEM, respectively. Acid Red B dyes, was degraded under solar light irradiation to evaluate the photocatalytic activity of the Er³⁺:YAlO₃/Fe-doped ZnO. In addition, the effects of Er³⁺:YAlO₃ content, heat-treatment temperature and time on the photocatalytic activity of Er³⁺:YAlO₃/Fe-doped ZnO were reviewed. Otherwise, the effect of initial dye concentration, Er³⁺:YAlO₃/Fe-doped ZnO amount and solar light irradiation time on the photocatalytic degradation of Acid Red B were also investigated. It was found that the photocatalytic activity of Er³⁺:YAlO₃/Fe-doped ZnO is much higher than that of Fe-doped ZnO and pure ZnO for the similar system. Perhaps, the use of the Er³⁺:YAlO₃/Fe-doped ZnO may provide a new way to take advantage of ZnO in sewage treatment aspects using solar energy.     

Improved photocatalytic degradation of reactive blue 81 using NiO-doped ZnO–ZrO2 nanoparticles

In this study, the photocatalytic degradation of Reactive Blue 81 (RB81) using synthesized NiO-doped ZnO–ZrO₂ nanoparticles under UV irradiation was investigated. Then, the products were characterized by Scanning electron microscope (SEM), X-ray diffraction (XRD), and diffuse reflectance spectroscopy (DRS). The removal rate of RB81 using ZnO–ZrO₂ after 180?min of irradiation was 96.7%. Nickel oxide (NiO) was used as an additive to ZnO–ZrO₂ for improvement of RB81 degradation via photocatalysis process. Photodegradation of RB81 was achieved to 100% using ZnO–ZrO₂–NiO nanoparticles with ratio of 1:2:0.3 after 180?min of irradiation. There was a red shift in absorption bands (from 410?nm to 435?nm) observed in increasing of NiO to ZnO–ZrO₂ nanoparticle, that it might lead to a higher photocatalytic activity under visible light. Response surface methodology (RSM) was used for optimization of experimental and these results were obtained: solution pH = 3, ZnO–ZrO₂–NiO dosage = 15?mg/L, and the initial RB81 concentration = 5?mg/L. The photodegredation of RB81 followed pseudo-first order kinetic according to the Langmuir–Hinshelwood model.     

Determination of bifonazole and identification of its photocatalytic degradation products using UPLC‐MS/MS

The main goal of the presented work was to investigate the effect of ZnO or/and TiO₂ on the stability of bifonazole in solutions under UVA irradiation. To this end, a simple and reproducible UPLC method for the determination of bifonazole in the presence of its photocatalytic degradation products was developed. Linearity was studied in the range of 0.0046–0.15 mg mL⁻¹ with a determination coefficient of 0.9996. Bifonazole underwent a photocatalytic degradation process under the experimental conditions used. Comparative studies showed that combination of TiO₂/ZnO (1:1 w /w) was a more effective catalyst than TiO₂ or ZnO with a degradation rate of up to 67.57% after 24 h of irradiation. Further, kinetic analyses indicated that the photocatalytic degradation of bifonazole in the mixture of TiO₂/ZnO can be described by a pseudo‐first order reaction. Statistical comparison clearly indicated that the presence of TiO₂/ZnO also affected the stability of bifonazole from a cream preparation after 15 h of UVA exposure (p < 0.05). Ten photodegradation products of bifonazole were identified for the first time and their plausible fragmentation pathways, derived from MS/MS data, were proposed. The main pathway in the photocatalytic transformation of bifonazole in the presence of ZnO or/and TiO₂ involves hydroxylation of the methanetriyl group and/or adjacent phenyl rings and cleavage of the imidazole moiety.     

Fabrication of urchin‐like Ag/ZnO hierarchical nano/microstructures based on galvanic replacement mechanism and their enhanced photocatalytic properties

Urchin‐like Ag/ZnO hierarchical nano/microstructures have been synthesized through a facile low‐temperature hydrothermal growth method based on galvanic replacement mechanism. The experimental results show that the urchin‐like Ag/ZnO heterostructures are formed through the epitaxial growth of ZnO nanorods on the {111} facets of Ag nanoparticles along their own c‐axis. The photocatalytic properties of the products were evaluated by the degradation of RhB dye solution under ultraviolet irradiation, and the results show that the products exhibit significantly enhanced photocatalytic properties comparing with pure ZnO nanorods. The products with a Ag content of 35.64 atom % prepared with a Ag⁺ concentration in solution of 5 mM exhibit surprisingly high degradation rate (99.5%) for RhB dye solution (4 mg/L) after photocatalytic reaction for only 14 min under ultraviolet irradiation. The Schottky barrier formed at the metal‐semiconductor interfaces improves the segregation of charges and prevents the charge recombination, and thus significantly enhances the photocatalytic activities of the products. On the other hand, the high stability of the urchin‐like Ag/ZnO hierarchical nano/microstructures can effectively prevent the aggregation of nanostructures with simultaneously preserving high photocatalytic properties due to the existence of nanosized unites. Copyright © 2016 John Wiley & Sons, Ltd.     

Heterostructured MgO/ZnO photocatalysts: Synthesis,Characterization and UV Light-Induced Photocatalytic Activity Using Model Pollutant 2,6-dichlorophenol

ZnO and MgO/ZnO (mass ratio 2: 5, 5: 5 and 8: 5) heterostructure photocatalysts (Mg₂Zn₅, Mg₅Zn₅ and Mg₈Zn₅, respectively) were successfully synthesized via co-precipitation method. MgO/ZnO composites were characterized by scanning electron microscopy (SEM), X-Ray diffraction and low temperature nitrogen adsorption–desorption isotherm. According to SEM images all composites consisted of spherical granules with particle sizes of 30–50 nm. The band gap value of ZnO was found to be lower than that of MgO/ZnO composites as observed during the optical studies. Pure ZnO showed lower photocatalytic activity (38%) in the degradation of 2,6-dichlorophenol (2,6-DCP) than MgO/ZnO composites. Mg₅Zn₅ composite with a higher concentration of defects in crystallites was more active in the photocatalytic degradation (79.5%) than Mg₈Zn₅ (61.2%) and Mg₂Zn₅ (63.5%). High-resolution mass spectrometry-and UV-Vis spectroscopic analysis of the by-products, derived from model pollutant 2,6-DCP, proved the successful photocatalytic performance of Mg₅Zn₅ under the UV light. The synthesized composites are future candidates against other potential environmental pollutants.     

ZnO修饰提升花状BiOBr的可见光催化降解罗丹明B性能

以Bi(NO₃)₃·5H₂O、Zn(CH₃COO)₂·2H₂O和NaBr为前驱体,采用简单溶剂热法制备BiOBr/ZnO三维花状微纳米复合材料。采用X射线衍射、扫描电子显微镜、X射线光子能谱、N₂吸附-脱附、光致发光和电子顺磁共振等分析技术对其理化性质进行了表征。通过可见光催化降解罗丹明B(RhB)的实验测试了复合材料的光催化性能。结果表明ZnO含量为5%的BiOBr/ZnO光催化活性最优,RhB降解率在50 min后达到98.3%,其降解速率常数是纯ZnO和BiOBr的6.3倍和3.4倍,并且具有较高的稳定性。复合材料光催化性能增强的可能原因为ZnO的引入增强了可见光的吸收和光生载流子的电荷分离效率。     

Degradation of toluene gas at the surface of ZnO/SnO2 photocatalysts in a baffled bed reactor

To eliminate volatile organic compounds (VOCs) from contaminated air, a novel medium-scale baffled photocatalytic reactor was designed and fabricated, using immobilized ZnO/SnO₂ coupled oxide photocatalysts. Toluene was chosen as a representative pollutant of VOCs to investigate the degradation mechanism and the parameters affecting photocatalytic degradation efficiency. The preliminary experimental results indicate that the degradation efficiency of toluene increased with the increase of the light irradiation dosage, while it decreased with the increase of concentrations of toluene. The degradation efficiency increased rapidly with the increase of the relative humidity in a low humidity range from 0 to 35%, but decreased gradually in a high relative humidity (i.e., >35%). The optimum experimental conditions for toluene degradation is a toluene concentration of 106 mg m^?3, a relative humidity of 35%, and an illumination intensity of ca. 6 mW cm^?2 at the surface of ZnO/SnO₂ photocatalysts. The intermediates produced during the gaseous photocatalytic degradation process were identified using the GC–MS technique. Based on these identified intermediates, the photocatalytic mechanism of toluene into ZnO/SnO₂ coupled oxide catalyst was also deduced.     

Enhancement of 2-chlorophenol photocatalytic degradation in the presence Co<Superscript>2+</Superscript>-doped ZnO nanoparticles under direct solar radiation

The performance of Co²⁺-doped ZnO nanoparticles, prepared using the sol–gel method, for 2-chlorophenol degradation under direct solar radiation was investigated. Various parameters were investigated during the degradation process, namely solar intensity, Co²⁺ ion concentration, loading concentrations of Co²⁺-doped ZnO, and pH. The photocatalytic degradation efficiency increased when the initial concentration of 2-chlorophenol decreased; the optimum concentration was 50 mg/L under similar experimental conditions. Moreover, optimum values, established on a sunny day, were 0.75 wt% of Co²⁺, a 1 g/L loading concentration, and a pH of 6.0, respectively. The highest degradation efficiency observed was 95 %, after only 90 min of solar light irradiation. The mechanism of visible photocatalytic degradation using Co²⁺-doped ZnO was explained as a strong electronic interaction between Co²⁺, Co³⁺ and ZnO, and a promotion in the charge separation, which enhanced the degradation performance. The fragmentation of 2-chlorophenol under the optimal conditions was investigated using HPLC, comparing standards of all intermediate compounds. The pathway of the fragmentation was proposed as involving hydroxyhydroquinone, catechol, and phenol formation, which were then converted to non-toxic compounds such as oxalic acid and acetic acid with further decomposition to CO₂ and H₂O.     

The improvement of solar photocatalytic activity of ZnO by doping with Er3+:Y3Al5O12 during dye degradation

The Er³⁺:Y₃Al₅O₁₂, an upconversion luminescence agent, which is able to transform the visible light to ultraviolet light, was synthesized by nitrate-citric acid method. And then, a novel photocatalyst, Er³⁺:Y₃Al₅O₁₂/ZnO composites, was prepared by ultrasonic dispersing and liquid boil method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the structural morphology and surface properties of the Er³⁺:Y₃Al₅O₁₂/ZnO. Azo Fuchsine dye was selected as target organic pollutant to inspect the photocatalytic activity of Er³⁺:Y₃Al₅O₁₂/ZnO. The key parameters affecting the photocatalytic activity of Er³⁺:Y₃Al₅O₁₂/ZnO, such as Er³⁺:Y₃Al₅O₁₂ content, heat-treatment temperature and heat-treatment time, were studied. In addition, the effects of dye initial concentration, Er³⁺:Y₃Al₅O₁₂/ZnO amount and solar light irradiation time were also reviewed, as well as the photocatalytic activity in degradation of other organic dyes were compared. It was found that the photocatalytic activity of Er³⁺:Y₃Al₅O₁₂/ZnO was much superior to pure ZnO under the same conditions. Thus, the Er³⁺:Y₃Al₅O₁₂/ZnO is a useful photocatalyst for the wastewater treatment because it can efficiently utilize solar light by converting visible light into ultraviolet light.     

Synthesis of nano-sized Ag3PW12O40/ZnO heterojunction as a photocatalyst for degradation of organic pollutants under simulated sunlight

With the rapid development of the world economy, water pollution has become increasingly serious. The photocatalytic degradation of pollutants is one of the most promising environmental treatment techniques. In this study, novel Ag₃PW₁₂O₄₀/ZnO nanoheterojunction was successfully constructed via a chemical process and was then characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, diffuse reflectance spectroscopy, Brunauer-Emmett-Teller analysis, and photoluminescence measurements. The synthesized nanoheterojunction exhibited good crystallinity and dispersity. The particle diameter of the composite was approximately 800 nm, the bandgap was 2.92 eV, and the specific surface area was approximately 10.5 m².g^?1. Under optimum conditions, the photocatalyst degraded 82.1% RhB in 60 min. Moreover, the novel Ag₃PW₁₂O₄₀/ZnO heterojunction also exhibited an excellent recycling stability. Hydroxyl radicals, superoxide radicals, and holes played important roles in the photocatalytic degradation process. A possible mechanism for the enhanced photocatalytic performance of the nanoheterojunction was proposed. This work provides a strong foundation for the application of Ag₃PW₁₂O₄₀/ZnO nanoheterojunction for treating environmental organic pollutants.     

Heterojunction α-Fe2O3/ZnO Films with Enhanced Photocatalytic Properties Grown by Aerosol-Assisted Chemical Vapour Deposition

Type I heterojunction films of α-Fe₂O₃/ZnO are reported here as a non-titania based photocatalyst, which shows remarkable enhancement in the photocatalytic properties towards stearic acid degradation under UVA-light exposure (λ=365 nm), with a quantum efficiency of ξ=4.42±1.54×10⁻⁴ molecules degraded/photon, which was about 16 times greater than that of α-Fe₂O₃, and 2.5 times greater than that of ZnO. Considering that the degradation of stearic acid requires 104 electron transfers for each molecule, this represents an overall quantum efficiency of 4.60 % for the α-Fe₂O₃/ZnO heterojunction. Time-resolved transient absorption spectroscopy (TAS) revealed the charge-carrier behaviour responsible for this increase in activity. Photogenerated electrons, formed in the ZnO layer, were transferred into the α-Fe₂O₃ layer on the pre-μs timescale, which reduced electron–hole recombination. This increased the lifetime of photogenerated holes formed in ZnO, which oxidise stearic acid. The heterojunction α-Fe₂O₃/ZnO films grown herein show potential environmental applications as coatings for self-cleaning windows and surfaces.     

Fe2O3/ZnO/ZnFe2O4 composites for the efficient photocatalytic degradation of organic dyes under visible light

In this study, novel ternary Fe₂O₃/ZnO/ZnFe₂O₄ (ZFO) composites were successfully prepared through a simple hydrothermal reaction with subsequent thermal treatment. The as-prepared products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH) measurement, and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic degradation of rhodamine B (Rh B) under visible light irradiation indicated that the ZFO composites calcined at 500 °C has the best photocatalytic activity (the photocatalytic degradation efficiency can reach up to 95.7% within 60 min) and can maintain a stable photocatalytic degradation efficiency for at least three cycles. In addition, the photocatalytic activity of ZFO composites toward dye decomposition follows the order cationic Rh B > anionic methyl orange. Finally, using different scavengers, superoxide and hydroxyl radicals were identified as the primary active species during the degradation reaction of Rh B.     

The photocatalytic degradation of cationic surfactant from wastewater in the presence of nano-zinc oxide using Taguchi method

The photocatalytic degradation of cetyl pyridinium chloride (CPC) has been investigated in aqueous phase using ultraviolet (UV) and ZnO nanopowder. Kinetic analysis showed that the extent of surfactant photocatalytic degradation can be fitted with pseudo-first-order model and photochemical elimination of CPC could be studied by Taguchi method. Our experimental design was based on testing five factors, i.e., dosage of K₂S₂O₈, concentration of CPC, amount of ZnO, irradiation time and initial pH. Each factor was tested at four levels. The optimum parameters were found to be pH 5.0; amount of ZnO 11 mg; K₂S₂O₈ 3 mM; CPC 10 mg/L; irradiation time, 8 h.     

Synthesis of ZnTiO3/tourmaline/Ni foam catalyst and enhanced photocatalytic performance

ZnTiO₃/tourmaline loaded on the nickel foam (ZnTiO₃/tourmaline/Ni-foam) is prepared by a facile coating method. Morphology and structure of the photocatalyst were characterized by X-ray diffraction (XRD), scanning electrons microscopy (SEM), raman spectroscopy, UV–vis diffuse reflectance spectrum (UV–vis DRS) and photoluminescence spectroscopy (PL). The photocatalytic properties of the materials were tested by using the Rhodamine B (RhB) solution as the target pollutant. The results indicates that the ZnTiO₃/tourmaline/Ni foam exhibited higher photocatalytic activity than that of ZnTiO₃ and ZnTiO₃/Ni foam under ultraviolet (UV) light irradiation, and its degradation rate was up to 99.2%. Moreover, the degradation rate remained at 91.3% after eight consecutive photocatalytic reaction cycles. The outstanding photocatalytic performances of ZnTiO₃/tourmaline/Ni foam was mainly attributed to the existence of tourmaline, which can help to inhibit the recombination of electron-hole paris, and the proper pore structure of the carrier. Meanwhile, the trapping experiments indicated that ·O₂^– was the main active species in the photocatalytic degradation of RhB.