Degradation Ratio Of Methyl Orange Research Articles

Preparation of muscovite/tungsten-doped TiO2 composites for the efficient photocatalytic degradation of methyl orange under simulated solar light irradiation

TiO 2 particles were supported on the surface of muscovite by van der waals force and Ti O Si bond, which improved the adsorbability and recyclability of TiO 2 . Meanwhile, W-doped could introduce new energy levels below the TiO 2 conduction band to reduce the band gap, enhance the absorption of sunlight, and promote the separation of electron-hole pairs, so as to improve the photocatalytic activity of the M/W-TiO 2 composite. • The M/W-TiO 2 composite photocatalyst was fabricated by one-step hydrothermal method. • Endow muscovite with the ability of photocatalysis. • The existence of W-doped energy level improves the separation efficiency of photogenerated carriers. • M/W-TiO 2 composites exhibit excellent photocatalytic activity and stability under simulated solar light irradiation. Metal oxide semiconductors have a widespread application in the photocatalytic treatment of dye wastewater but there is a need to improve the current ‘champion’ titanium dioxide (TiO 2 ) due to its difficult recovery, low utilization rate of sunlight, and fast recombination of electron-hole pairs. To solve the problems, muscovite-supported TiO 2 with tungsten dopant (M/W-TiO 2 ) photocatalyst was synthesized using a facile hydrothermal method in this study. The obtained samples were characterized by XRD, Raman, SEM, BET, XPS, DRS, PL, and EIS. The results revealed that Ti O Si bond formed between TiO 2 and the surface of muscovite, and the hexavalent W 6+ entered the TiO 2 crystal lattice to substitute the tetravalent Ti 4+ . Compared with the undoped M/TiO 2 , the absorption edge of W-doped samples exhibited a redshift, and the separation efficiency of the photo-induced carriers was improved. The highest photocatalytic activity was achieved when the doping amount of W was 0.5%, and the degradation ratio of methyl orange (MO) reached 98.4% after simulated solar light irradiation for 120 min. This research can provide a novel strategy to prepare highly efficient and stable TiO 2 -based photocatalytic materials.

Three Isomeric Zn(II)-Sn(IV)-Zn(II) Porphyrin-Triad-Based Supramolecular Nanoarchitectures for the Morphology-Dependent Photocatalytic Degradation of Methyl Orange.

Three isomeric Zn(II)–Sn(IV)–Zn(II) porphyrin-based triads (T2, T3, and T4) were synthesized by the reaction of common Zn(II) porphyrins (ZnL) with different Sn(IV) porphyrins (SnPn). The Sn(IV) porphyrin precursors differ with respect to the position of the pyridyl-N atoms. All compounds were characterized by 1H NMR, UV–vis, fluorescence spectroscopy, electrospray ionization–mass spectrometry, and field-emission scanning electron microscopy measurements. In these structures, the intramolecular cooperative metal–ligand coordination of the 3-pyridyl nitrogen in SnP3 with axial ZnL and the π–π interactions between the adjacent porphyrin triad are the determining factors affecting the nanostructures of T3. Owing to the geometrical constraints of the SnP2 center, this type of interaction is not possible for T2. Therefore, only the π–π interactions affect the self-assembly process. In the case of SnP4, intermolecular coordinative interactions and then π–π interactions are responsible for the nanostructure of T4. The morphology-dependent photocatalytic degradation of methyl orange (MO) dye in aqueous solution under visible light irradiation was observed for these photocatalysts, and the degradation ratio of MO varied from 76 to 94% within 100 min. Nanorod-shaped T3 exhibited higher performance compared to nanosphere T2 and nanoflake T4.

Fe3O4-NPs/orange peel composite as magnetic heterogeneous Fenton-like catalyst towards high-efficiency degradation of methyl orange.

Magnetite nanoparticles (Fe3O4-NPs)/orange peel (MOP) composite was prepared via one-step in-situ co-precipitation method as magnetic heterogeneous Fenton-like catalyst. The properties of MOP were characterized by scanning electron microscopy, transmission electron microscopes, Brunauer-Emmett-Teller, X-ray diffraction, Fourier-transform infrared, thermogravimetric analysis and X-ray photoelectron spectroscopy technologies. Its Fenton-like catalytic responses towards removal of methyl orange (MO) were investigated, in which the effects of initial dye concentration, pH, temperature and hydrogen peroxide dosage were studied. The MO degradation ratio up to 98.0% was obtained within 20 min in optimized conditions. The catalyst showed excellent catalytic stability exhibiting nearly 90% degradation ratio in the 10th cycle within 20 min, whereas pure Fe3O4-NPs showed only 62.5% in this stage. Due to the stabilization of complexing orange peel hydroxyl to iron oxide in the composite and its magnetic separation property, MOP composite exhibits excellent Fenton-like catalytic performance, which offers great prospects for low-cost and high-efficiency organic dye wastewater treatment.

Effects of surfactants on the morphology and properties of TiO2

TiO2 nanoparticles with controllable morphology perform well in both physical and chemical properties, which have great significance in photocatalytic degradation of wastewater and photodegradation of water. In this study, TiO2 was prepared by solvothermal method with tetrabutyl titanate as titanium source, acetic acid as solvent and surfactant as additive. The effects of single and mixed surfactants, such as cetyltrimethylammonium bromide (CTAB), polyethylene glycol (PEG) and carboxamide, on the microstructure of TiO2 were systematically studied. The results showed that the prepared TiO2 was anatase phase. It clearly demonstrated the procedure how the morphology and size of TiO2 were influenced by surfactant. In the reaction system, when carboxamide was added to TiO2, CTAB or PEG, TiO2 nanocrystals gathered to form rod, cluster or similar ellipse, respectively. When two or more different surfactants were added to the system simultaneously, the morphology of TiO2 could be cauliflower-like, spherical and three-dimensional flower-like structures formed by the directional aggregation of nanocrystals due to the coordination between the surfactants. The photocatalytic properties of methyl orange were investigated under UV irradiation. The results showed that the photocatalytic properties of cauliflower-like structures, spherical structures and three-dimensional flower-like structures formed by the directional aggregation of nanocrystals were better than those of commercial Degussa P25. TiO2 nanoparticles with three-dimensional flower-like structures exhibited good photocatalytic performance, with the degradation ratio of methyl orange 94% under simulated irradiation for 60 min.

Degradation of methyl orange by a new catalyst glyphosate ferrous

A new metalorganic compound glyphosate ferrous with particle diameter about 150 nm was synthesized in this paper. Research results indicate that the compound has good catalytic properties on degradation of methyl orange (MO). There is about 99.48% of MO was degraded in 10 min when content of glyphosate ferrous in the reactive system was 0.2 g L−1, the reaction temperature was at 70 °C, pH value of MO solution was about 3.0 and 11.75 mmol of H2O2 was consumed in 1 L solution. Also good structural stability and high recyclability of the catalyst was found, and degradation ratio of MO was still about 99.45% after the ferrous complex was recycled 6 times under the same reaction conditions. All the results indicate good application prospects of the catalyst in dye wastewater treatment for its cheap raw materials and simple synthesis method.

Synthesis of flower-like CuS/graphene aerogels for dye wastewater treatment

A novel visible-light flower-like CuS/graphene aerogels (CuS/GAs) photocatalyst has been synthesized via two-step solvothermal method. The CuS/GAs show outstanding synergies of adsorption and photocatalysis for anionic–cationic dyes degradation, which is attributed to unique network structure and excellent photoelectric properties of GAs. The high degradation ratio of Methyl orange and Methylene blue by synergy are 92% and 99.36%, which are about 4.1 and 3.2 times of that for pure CuS. The flower-like CuS/graphene aerogels resolve the low adsorption saturation problem of GAs and improve the photocatalytic performance of CuS, indicating CuS/GAs could be a promising photocatalyst for wastewater treatment.

Preparation and Photochemical Properties of Layered MoS2/Cu2o Heterojunction Nanocomposites

In recent years, environmental problems induced by organic pollutants have become an important problem for our society. Semiconductor photochemical treatment is a potential technology for solving the environmental issues. Therefore, lots of efforts have been devoted to develop high-efficiency visible light assisted semiconductor photocatalysts. Cu2O nanoparticle is a well-known p-type semiconductor with a direct band gap of 2.17eV, which endows it a reasonable alternative for photocatalytic applications [1-3]. However, high recombination rate of the electron-hole pairs excited from Cu2O nanoparticles seriously hinders its practical application. Coupling p-type Cu2O nanoparticles with n-type semiconductor to form a P-N heterojunction for carrier separation and produce appropriate energy level difference for charge transfer from one semiconductor to another is a potential approach to decrease recombination rate for high-efficiency degradation. Graphene-like n-type semiconductor MoS2 multilayered nanoplates are the reasonable alternative due to its tunable bandgap with different layers and large amounts of unsaturated active sites [4-5]. In this work, two-dimensional (2D) MoS2 nanoplates with different multilayer thickness were prepared by liquid exfoliation and gradient centrifugation. Then, the MoS2 nanoplates were utilized to match the energy level of Cu2O nanoparticles to form MoS2/Cu2O nanocomposites, which have been achieved by the method of hydrothermal synthesis. Scanning Electrom Microscope images and X-ray diffraction (XRD) pattern of nanoparticles Cu2O and MoS2/Cu2O nanocomposites are shown in Fig.1. It can be seen that the morphology of Cu2O nanoparticles are truncated octahedron structure and closely attached on MoS2 nanosheets with different thickness, which was obtained at the centrifugation speed of 2000 rpm, 4000 rpm, 6000 rpm and 8000 rpm. The photochemical behaviors of Cu2O nanoparticles and different MoS2/Cu2O nanocomposites are characterized through the degradation behaviors of methyl orange (MO) under visible light irradiation (Fig.2). The experimental results show that the degradation efficiency of MoS2/Cu2O nanocomposites can be improved by optimizing the thickness of MoS2 nanoplates from few layers to bulk. The degradation ratios of MO after 3 h are 57.9%, 61.1%, 92.2%, 95.3%, 93.1%, and correspond respectively to the MoS2/Cu2O nanocomposites in which the MoS2 nanosheets were obtained at the centrifugation speed of 0 rpm, 2000 rpm, 4000 rpm, 6000 rpm and 8000 rpm. The possible reason is that the increasing surface area and bandgap of MoS2 may provide large reaction area and produce appropriate energy level difference, which is beneficial for accelerating the degradation process of methyl orange. In summary, the different MoS2/Cu2O heterojunction nanocomposites were prepared through adjusting the thickness of multilayered MoS2 nanoplates. The results show that the optimized degradation ratio of MO can be greatly improved from 57.9% up to 95.3% after 3h using MoS2/Cu2O nanocomposites in comparison with Cu2O nanoparticles.

Preparation and photo Fenton-like activities of high crystalline CuO fibers

CuO fibers were successfully fabricated by a simple electrospinning method, followed by calcination. Some experimental parameters such as the content of Cu(NO3)2∙3H2O, the content of PVP, the stirring time, the applied voltage, as well the calcination temperature were investigated, respectively, and their influences on the morphologies of fibers and the spinnability of precursor solution were analyzed. The CuO fibers calcined at 550°C consisted of numerous CuO grains exhibited a well-crystalline structure. Furthermore, the CuO fibers demonstrated effective photo-Fenton degradation to methyl orange with the assist of H2O2 and the adding volume of H2O2 affects the degradation activities greatly. The degradation rate of methyl orange by the CuO fibers in the presence of 238.8mmol/L H2O2 is 3.8 times as much as one by P25 alone under the irradiation of Xe lamp. The degradation ratio of methyl orange could achieve 83% in 180min. The enhanced photocatalytic activities of the CuO fibers were attributed to two aspects: one is the well-crystalline of CuO fibers; the other is that H2O2 accepted the photogenerated electrons and holes effectively, which not only prevented the recombination of charge carriers but also produced additional OH. In this work, the formation and photocatalysis mechanisms of CuO fibers were also investigated.

Mesoporous black Ti3+/N-TiO2 spheres for efficient visible-light-driven photocatalytic performance

Mesoporous black Ti3+/N-TiO2 spheres with high crystallinity are fabricated by a facile evaporation-induced self-assembly (EISA) method, using urea as nitrogen resource, combined with a mild calcinations (350°C) after an in-situ hydrogenation under an argon atmosphere. The prepared materials are characterized by X-ray diffraction, Raman, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results indicate the prepared sample is uniform mesoporous black Ti3+/N-TiO2 spheres with high crystallinity of anatase, high surface area of ∼100m2g−1, large pore size of 6.5nm and narrow band gap of 2.11eV, could be easily controlled with the diameter from 200 to 800nm. Meanwhile, the photoresponse extends to near-infrared region owing to Ti3+ and N codoping. The visible-light-driven photocatalytic degradation ratio of methyl orange is up to 96% and photocatalytic hydrogen production rate is ∼150μmolh−1, which are several times higher than that of pristine TiO2. Besides, the possible photocatalytic mechanism is proposed. The excellent photocatalytic activity can be ascribed to N and Ti3+ doping resulting in high visible light utilization and enhanced separation of photogenerated charge carriers, and the mesoporous networks offering more surface active sites.

The synthesis and characterization of ytterbium-doped TiO2 hollow spheres with enhanced visible-light photocatalytic activity

SEM images of Melamine-formaldehyde polymer microspheres (MF) (a) and Yb-doped TiO2 hollow spheres (Yb-TiO2HS) (b).

Enhanced ultrasound-assisted degradation of methyl orange and metronidazole by rectorite-supported nanoscale zero-valent iron

In this study, the rectorite-supported nanoscale zero-valent iron (nZVI/R) was synthesized through a reduction method. X-ray diffraction analysis showed the existence of the nZVI in the nZVI/R composite and X-ray photoelectron spectroscopy analysis indicated that the nZVI particles were partly oxidized into iron oxide. Scanning electron microscopy analysis revealed that the nZVI particles were highly dispersed on the surface of the rectorite. The specific surface area of the nZVI/R composite is 21.43m2/g, which was higher than that of rectorite (4.30m2/g) and nZVI (17.97m2/g). In the presence of ultrasound (US), the degradation of methyl orange and metronidazole by the nZVI/R composite was over 93% and 97% within 20min, respectively, which is much higher than that by the rectorite and the nZVI. The degradation ratio of methyl orange and metronidazole by the nZVI/R composite under US was 1.7 and 1.8 times as high as that by the nZVI/R composite without US, respectively. The mechanism of the enhanced degradation of methyl orange and metronidazole under US irradiation was studied. These results indicate that the US/nZVI/R process has great potential application value for treatment of dye wastewater and medicine wastewater.

Highly Active S-Doping MnFe<sub>2</sub>O<sub>4</sub> by Synthesis and Photo-Fenton Catalytic Property Research

Composite oxide MnFe2O4 have been synthesized via the hydrothermal process and then modified by S=O. These compounds were characterized by X-ray diffusions, and ultraviolet-visible diffusion reflectance spectroscopy. MnFe2O4 exhibits stronger photocatalytic activity, with 95.5% degradation ratio of methyl orange and 91% degradation ratio of basic fuchsin, after 120 minutes visible-light irradiation in the presence of H2O2. In addition, the effect of pH values on photocatalytic activity were also investigated.

The synthesis of NdFeB magnetic activated carbon and its application in degradation of azo dye methyl orange by Fenton-like process

In this paper, the magnetic NdFeB-activated carbon Fenton catalyst (NdFeB-AC-FC) was synthesized by negative pressure impregnation method. The results of magnetite susceptibility measurement show that the NdFeB-AC-FC had hard magnetic properties. Its saturated magnetization, remanent magnetism and coercive force were 18.11emu/g, 5.7emu/g, and 905Oe, respectively. The surface morphology and elementary composition test results show that the specific area and Fe content of NdFeB-AC-FC have been significantly improved by negative pressure impregnation treatment. The feasibility of the NdFeB-AC-FC as catalyst in heterogeneous Fenton-like process has been studied by degrading the simulated dye wastewater. The results show that the NdFeB-AC-FC not only had splendid catalytic activity, but also had reused feasibility in heterogeneous Fenton-like process. Under the optimum conditions ([methyl orange (MO)]0=20mg/L, temperature=20°C, [NdFeB-AC-FC]0=10g/L, [H2O2]0=0.6mmol/L and pH=3.0), MO degradation ratio also could reach 97.1% after 5 cycles. In addition, the results of kinetics study show that the catalytic degradation process follows the pseudo-first order kinetics model. In a word, the catalyst has a good application prospect and it could provide a new technique to solve organic industrial wastewater pollution.

Preparation of nanocrystalline Cu2O by a modified solid-state reaction method and its photocatalytic activity

The nanocrystalline Cu2O was successfully prepared by calcining the precursor synthesized by a ball-milling step using Cu2(OH)2CO3 and H2C2O4·2H2O as initial reactants without any other additives. The as-synthesized precursor and the resulting calcined product are characterized by XRD and TG/DTA. The result shows that the reaction between Cu2(OH)2CO3 and H2C2O4·2H2O is complete after 15min of milling and the precursors are of the crystalline sizes between 17 and 37nm. The Cu2O is obtained with crystallite sizes of 15–21nm after the ball-milled precursors is calcined at 310°C for a certain time. The XRD also shows that the ball-milling time and the calcining time influence the crystallite sizes of the products to a certain extent. The average crystallite sizes of Cu2O decreases gradually with the increase of ball milling time, while they increase gradually with the increase of calcining time. In addition, the prepared Cu2O exhibits a high catalytic activity for the photodegradation of methyl orange under visible light irradiation, and the photocatalytic degradation ratio of methyl orange reaches to 88.7% after 2h of irradiation.

Photocatalytic activity of sulfated Mo-doped TiO2@fumed SiO2 composite: A mesoporous structure for methyl orange degradation

In this paper, a novel ultraviolet and visible light responsive photocatalyst, sulfated Mo-doped TiO2@fumed SiO2 composite, was synthesized by a feasible sol–gel method. A mesoporous structure and anatase crystallites were comfirmed by TEM, XRD and BET. The prepared catalysts exhibited good photocatalytic activity under both ultraviolet and visible light irradiation for methyl orange (MO) degradation. The XPS, UV–vis and FT-IR spectra indicated the high active sites on the surface were caused by doping Mo and performing the sulfation. The composite catalyst with 0.5% Mo dosage showed the highest photocatalytic activity. And the composite catalyst can be recycled for 6times, remaining 90.0% MO degradation ratio under UV irradiation. The high surface area and high active sites on the composite surface are considered as the key factors.

The Photocatalytic Activity of Nano-TiO2 (anatase) Gradient Coating on Tourmaline Beads

Gradient nano-TiO2(anatase) /tourmaline beads were prepared by sol impregnated method, and the phase composition and microstructure of gradient coating were characterized by XRD and SEM, and the photocatalytic activity were evaluated by degradation of methyl orange (MO), compared with that of pure nano-TiO2 (anatase), tourmaline beads. The result indicated that the MO degradation ratio by tourmaline beads is 5.8%; that by pure nano-TiO2 (anatase) is 38.2%; while the MO degradation ratio approached 70.4% by gradient nano-TiO2 (anatase) /tourmaline beads, much better than the other two types of catalysts. When the gradient nano-TiO2 (anatase) /tourmaline beads are illuminated by UV irradiation, the electron-hole pairs are generated and the photogenerated carrier will be adsorbed tightly on the anode of tourmaline, owing to its strong electrostatic field, which suppresses the recombination of the electron-hole pairs, and enhances photocatalytic efficiency.

Surfactants Effect on the Photoactivity of Fe-Doped TiO<sub>2</sub>

Ti (OC4H9)4 was used as the Ti precursor and titanium dioxide (TiO2) was prepared by sol-gel method. During the preparation process, Fe3+ was doped and different surfactants, such as SDS, PEG, CTAB, were added to improve the photocatalytic activity of TiO2. The effect of the different type of surfactants on the structure of Fe-doped TiO2 was discussed. The photocatalysts were characterized by thermogravimetric thermal analysis, X-ray diffraction, scanning electron microscopy and UV-Vis spectrophotometer. The red shift of the absorption edge of the Fe-doped TiO2 prepared by using different surfactants was observed. Methyl orange (MO) solution was degraded under sunlight irradiation to evaluate the photocatalytic performance. The results indicated that the photocatalyst prepared with PEG addition had the highest activity and MO degradation ratio could reach 90% after 4 hours irradiation with the best photocatalyst.

SrBi<sub> 4</sub>Ti<sub> 4</sub>O<sub> 15</sub>的Pechini法制备及其光催化性能*

以硝酸锶、硝酸铋和钛酸丁酯为原料，柠檬酸为配位剂，乙二醇为溶剂，用Pechini溶胶–凝胶法制备了SrBi4Ti4O15粉体。研究了柠檬酸量、溶液pH值、乙二醇用量、煅烧温度对产物物相的影响。对所合成粉体进行形貌分析和光催化性能测试。经多组对比试验表明，在pH = 7.0、金属离子：柠檬酸 = 1:3、柠檬酸：乙二醇 = 1:2、干凝胶在650℃煅烧3 h可以得到单相SrBi4Ti4O15粉体。产物SrBi4Ti4O15的结构较疏松，带宽为3.01 eV，在金卤灯下照射3.5 h对甲基橙的降解率可达96.6%。 SrBi4Ti4O15 was prepared by a Pechini sol-gel method, using strontium nitrate, bismuth nitrate penthydrate and tetrabutyl titanate as raw materials, citric acid as ligand, and ethylene glycol as solvent. The influences of the amount of citric acid, pH, ethylene glycol and calcining temperature on the phases of the product were researched. The morphology and photocatalytic properties of the as-synthesized powders were measured. The multiple comparison tests showed single phase of SrBi4Ti4O15 was obtained under the conditions of pH = 7, metals:citric acid = 1:3, citric acid:glycol = 1:2, calcining the dry gel at 650C for 3 h. The as-synthesized SrBi4Ti4O15 had a loose structure with a bandwidth of 3.01 eV. The degradation ratio of methyl orange reached up to 96.6% under the metal halide lamp irradiation for 3.5 h.

Degradation of Methyl Orangle by Magnetic Metal Doped TiO<sub>2</sub> Films in a Magnetic Field

In order to find an effective way to degrade the effluent, the Cu/TiO2, La/TiO2, Cr/TiO2 films with unique 3-D network structures were prepared using Ti(OBu)4 by sol-gel method loaded on the gauzes. These films structures were characterized by means of XRD and SEM. The effects of doped TiO2 films and combination of magnetic field and doped TiO2 films on the degradation of methyl orange (MO) were studied. The results indicated that after combinating the magnetic field, the photocatalysis efficiency of doped TiO2 films have been improved,especially the influence on Cu/TiO2 film was more obvious than other films.When magnetic intensity was around 30mT ,the MO degradation ratio went up to 60% by using Cu/TiO2 films.But the influences of magnetic intensity on photocatalytic activities of doped TiO2 films had a maximum value which was 30mT.

A novel BiOCl thin film prepared by electrochemical method and its application in photocatalysis

In this study, a novel BiOCl thin film with flakelike structures has been successfully prepared through electrochemical method composed of a cathodic electrodeposition and an anodic oxidation at room temperature. The samples obtained at the different oxidation voltages were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), electronic energy spectrum (EDS), and UV–vis diffuse reflectance spectra (UV–vis DRS). The analysis results show that the morphological, structural, and optical characteristics of BiOCl thin films depend markedly on the anode oxidation voltage and the lattice orientation of BiOCl thin film is transformed mainly into (110) surface with the increasing oxidation voltages. The observed results of high-resolution transmission electron microscopy (HRTEM) confirm that pure tetragonal BiOCl thin film with the highly exposed (110) surface is obtained at 2.0V and consists of interlaced nanosheets. First-principles calculations reveal that the existence of BiOCl (110) surface states enhances the electron transition and efficient separation of photo-induced electron–hole pairs. The optimized BiOCl thin film can not only guarantee the intrinsic photochemical properties of BiOCl bulk but also exhibit additional electronic characteristics of BiOCl (110) surface, and consequently the wonderful synergistic effect between BiOCl bulk and BiOCl (110) surface accelerates the efficient separation of electron–hole pairs and produces the high reducing superoxide radicals O2− and strong oxidizing hydroxyl radicals OH required for the degradation of organic compounds. For as-prepared BiOCl thin film, the degradation ratio of methyl orange (MO) reaches 98% under 2.5h UV irradiation at the first cycle and still remains 90% at the fifth cycle, and the COD removal efficiency of 50mg/L MO solution over BiOCl thin film achieves 73.47% after 8h reaction time. The BiOCl thin film with highly exposed {110} facets exhibits the excellent photocatalytic performance and potential application in photocatalysis field.