Methyl Orange Solution Research Articles

Enhanced visible-light photocatalytic activity and recyclability of magnetic core-shell Fe3O4@SiO2@BiFeO3–sepiolite microspheres for organic pollutants degradation

Novel magnetic core-shell structured Fe3O4@SiO2@BiFeO3–sepiolite microspheres were fabricated via a facile hydrothermal method. The as-prepared microspheres comprised a Fe3O4@SiO2 magnetic core with a strong response to external fields and a porous BiFeO3/sepiolite composite functional layer. The specific surface area, magnetization saturation value (Ms), and band gap energy (Eg) of Fe3O4@SiO2@BiFeO3–sepiolite (x = 0.4 g) were 126.68 m2/g, 18.2 emu/g, and 2.09 eV, respectively. A suitable amount of sepiolite in Fe3O4@SiO2@BiFeO3–sepiolite could improve the microstructure of the photocatalyst through the interface effect between the sepiolite and the formed BiFeO3, which can enlarge the specific surface area and thus increase the absorption of light and the adsorption of pollutants, decrease the Eg of the as-prepared photocatalyst, and improve the separation and inhibit the recombination of photogenic electron and hole (e−/h+) pairs, thereby expediting the photocatalytic degradation of pollutants. The as-obtained Fe3O4@SiO2@BiFeO3–sepiolite (x = 0.4 g) exhibited a remarkable photocatalytic degradation performance for ciprofloxacin (CIP), tetracycline hydrochloride (TC-H), and methylene blue (MB) and an excellent decolorization for the mixed solution of methyl orange (MO), rhodamine B (Rh B), and MB under visible-light irradiation. In addition, the as-obtained photocatalyst demonstrated excellent magnetic separation performance, recyclability, and stability. The active species produced during the photocatalysis included OH, O2−, and h+, with OH being the dominant active species. Such a well-structured core-shell photocatalyst has remarkable potential for numerous applications in treating organic wastewater.

Study on the adsorption properties of methyl orange by natural one-dimensional nano-mineral materials with different structures

Methyl orange (MO) is a common anionic azo dye that is harmful to the environment and biology, so it must be treated innocuously before it can be discharged. Adsorption is an effective method to remove anionic dyes. Nanotube mineral is a natural one-dimensional adsorption material, and its unique morphology and structure endow it with good adsorption capacity. Although there are many related studies, there is a lack of in-depth discussions on the influence of nanotube’s composition and structure on the adsorption of dyes and other pollutants. In this paper, two kinds of natural one-dimensional silicate minerals [halloysite nanotubes (HNTs) and chrysotile nanotubes (ChNTs)] with similar morphology but slightly different compositions and crystal structures were used as adsorbents, and MO solution was used as simulate pollutants. It is the first time to discuss in depth the influence of the composition and structure of nanotube minerals on their charge properties and the adsorption performance of methyl orange dyes. It is found that HNTs and ChNTs have different adsorption capacity due to the difference of electronegativity between Al3+ and Mg2+ in the crystal, so they possess negative and positive charges respectively in near-neutral solution, which leads to the adsorption capacity of MO by ChNTs with positive charges which is greater than that of HNTs.

Pullulan/poly(N‐vinylimidazole) cryogel: An efficient adsorbent for methyl orange

AbstractPullulan/poly(N‐vinylimidazole) (PNVI) hybrid cryogels were synthesized under free radical polymerization and chemical crosslinking conditions in an alkaline, aqueous solution of pullulan (PUL), N‐vinylimidazole (NVI), ammonium persulfate and epicholorohydrin (ECH) at −18°C. PUL and PNVI cryogels alone were also synthesized under similar conditions. Optimum cryogel formation conditions were determined by considering product yields and gel fractions of the samples. The products were characterized by elemental analysis, FTIR‐ATR spectrometry, Thermal gravimetric analysis, and scanning electron microscopy (SEM) analyses. It has been found that PUL/PNVI hybrid samples bear improved physicochemical properties compared to ECH crosslinked PUL and PNVI samples alone. They act as hydrogels in aqueous medium reaching equilibrium swelling capacity values of the order of 600%. Dried PUL/PNVI cryogels show higher thermal stability than the dried cryogels of the parent polymers and maintain their physical integrity over a prolonged time period. Macroporous morphology was revealed by SEM analysis. Having 54.2 mg/g maximum equilibrium adsorption capacity in 200 ppm methyl orange solution and maintaining 95% of its adsorption capacity at the end of seven consecutive adsorption/desorption cycles, PUL/PNVI cryogel proved to be an efficient and durable dye adsorbent using methyl orange as the model compound in aqueous solution.

Environmentally benign hybrid nanocomposite beads for azo dye remediation via synchronized dual degradation mechanisms.

Practically, 12% of used dyes are excluded as waste in the mobile aqueous environment. Methyl orange (MO), an industrial azo dye, is known to be carcinogenic. Accordingly, this work was engaged to fabrication of a high-efficiency visible light photocatalysts based on Ag-Alginate/Chitosan-coated MgO nanocomposite beads. MgO and Ag were prepared via precipitation and γ-radiation reduction technique as a green physical one, respectively. The degradation mechanisms depended on catalytic reduction by means of sodium borohydride/Ag and photooxidative degradation. XRD proved the periclase crystalline form of MgO of size 20 nm and the formation of face-centered cubic silver crystals of size 15 nm. The degradation yield varied directly with time, MgO, and dye concentration until certain limit. Five and twenty minutes were enough to get clear solution of MO (30 and 15 ppm, respectively) while 60 min was required to achieve the same target for 60 ppm MO solution. The catalysts showed high efficiency for MO of high concentration. The incorporation of Ag into catalytic beads could support both mechanisms as it could elevate the degradation efficiency up to 50% and save the time to a great extent. Thus, this carrier fruitfully converted wastewater into an effluent that can be repaid to the water cycle with minimal strike on the ecosystem.

Synthesis and characterization of Zn-doped α-Fe2O3 nanoparticles with enhanced photocatalytic activities

In present work, the optical, magnetic and photocatalytic properties of undoped and Zn doped α-Fe2O3 nanoparticles was investigated intensively. The Zn doped hematite nanoparticles were synthesized by simple co-precipitation method, changing the molar ratio of zinc precursors. The obtained photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infra-red (FTIR), Raman spectroscopy, diffuse reflectance UV–visible spectroscopy (DRS) and vibrating sample magnetometer (VSM). The structural properties showed that the obtained nanoparticles are single phase rhombohedral (hexagonal) structure with the space group R-3c in all compounds. TEM and SEM results show that the size of the nanocrystals decreases with Zn-doping down to 21 nm. Raman spectroscopy was also used for confirming zinc atoms replacing iron position in Zn doped α-Fe2O3 crystal. The energy gap decreased gradually by increasing the doping concentration of zinc. The specific saturation magnetization (Ms) of the nanoparticles was measured at room temperature. The magnetic parameter of Ms, was found to decrease with the increase in Zn concentration. Zinc doped α-Fe2O3 showed the enhanced photocatalytic properties within photodegradation of methyl orange (MO). The 6% Zn-doped α-Fe2O3 nanoparticles showed the highest photocatalytic activity and led to an almost complete discoloration of MO solutions, i.e. 87.4% at pH = 4 after UV–visible irradiation of 140 min.

Investigation of methyl orange photocatalytic degradation using La0.7Sr1.3CoO4 Ruddlesden-Popper nanoparticles

In this research, photocatalytic properties of La0.7Sr1.3CoO4 Ruddlesden-Popper oxide have been investigated on methyl orange (MO) dye degradation under UV irradiation for the first time. Nanopowders of La0.7Sr1.3CoO4 were synthesized by a modified sol-gel method. The synthesized powders were characterized using XRD analysis, FE-SEM and TEM imaging techniques, Raman and UV–Vis spectroscopy. The XRD pattern revealed that the synthesized powders crystalize in tetragonal structure with I4/mmm space group and the optical band gap was evaluated about 2.5 eV, using tauc equation. Photo-degradation of 20 mL of MO solution was studied for different amounts of La0.7Sr1.3CoO4 (0.025, 0.050 and 0.1 g), as the photocatalysts. Moreover, the effect of different amounts of hydrogen peroxide (H2O2), as an electron acceptor, on the catalytic reaction was also investigated. Our results showed that MO degradation efficiency over the optimal amount of La0.7Sr1.3CoO4 was about 94% under UV irradiation after 75 min. This efficiency and the rate of MO degradation was found to increase with the presence of H2O2, as an oxidant. These results suggest that La0.7Sr1.3CoO4 nanopowder can be considered as a good and promising photocatalyst for dye degradation.

Optimization of UV light source conditions for photocatalytic activity of methyl orange using TiO2

Methyl orange is one of the azo compounds which carcinogenic and damages the water system if untreatead properly. This compound is used in the textile industry as a coloring agent. Dyestuff waste produced from the textile industry is generally a non-biodegradable organic compound, which cause environmental pollution, especially at the aquatic environment. As organic waste, it is necessary to treat this compound to be harmless and safe for the environment. One of the method to remove dye waste is by using photocatalytic reaction using TiO2 as semiconductor. In this study, optimization of UV light source conditions of the photocatalytic reaction was carried out inside a photoreactor system using TiO2 synthesized by hydrothermal method. Optimization of the distance of UV lamps from the surface of methyl orange solution and UV lamps power has been done under the artificial UV light sources with 254 nm wavelength. The percentage of degradation was determined by measuring the absorbance of methyl orange solution before and after degradation using UV-Vis spectrophotometer. It shows that the optimum photocatalytic activity for the distance of UV lamps and UV lamps power is 20 cm and 20 Watt respectively. Physically, there was color changing during the reaction from orange to colorless.

Alkali Lignin from Rice (Oryza sativa L.) Husk as Adsorbent for Aqueous Methyl Orange and Bromothymol Blue: Analysis of the Adsorption Kinetics and Mechanism

In this study, lignin was isolated from rice (Oryza sativa L.) husk using alkaline extraction method and was used as an adsorbent for aqueous solutions of methyl orange (MO) and bromothymol blue (BTB). The equilibrium removal rate of MO was found to be at 61.4%, with experimental equilibrium adsorbate uptake, qe, of 1.23 mg·g-1, achieved at 150 minutes contact time. For BTB, the equilibrium removal rate was found to be at 78.3%, with an experimental qe of 1.57 mg·g-1, achieved at 150 minutes contact time. Pseudo-first order (PFO) and pseudo-second order (PSO) kinetic models were then used to investigate the kinetics of the adsorption process. Both MO and BTB on lignin were found to follow a PSO kinetic model, with rates of 6.84 x 10-3 g·mg-1·min-1 and 0.69 g·mg-1·min-1, respectively. Langmuir, Freundlich, Dubinin-Radushkevich (DR), Brunauer-Emmett-Teller (BET), Flory Huggins (FH), and Temkin adsorption isotherm models were then used to determine the appropriate equilibrium adsorption model for both substrates. Based on the calculations performed, the Temkin model best described the adsorptive removal of both MO and BTB. Based on the Temkin model, the adsorption processes of both MO and BTB were found to occur spontaneously, with equilibrium rate constants of 0.083 L·mg-1 and 0.012 L·mg-1, respectively.

Bismuth vanadate/MXene (BiVO4/Ti3C2) heterojunction composite: enhanced interfacial control charge transfer for highly efficient visible light photocatalytic activity.

We have synthesized BiVO4/Ti3C2 nanocomposite via a low-cost hydrothermal method and investigate its photocatalytic degradation activity against monoazo (methyl orange) and diazo dye (Congo red) in an aqueous solution under visible light. The physiochemical characterization exhibited that the addition of MXene in pristine BiVO4 nanocomposite led to an increase in specific surface area and reduction in optical band gap energy. MXene also helps in enhancing visible light response via a higher electron-hole pair generation rate and long lifetime. The synthesized BiVO4/Ti3C2 heterojunction composite exhibited 99.5 % degradation efficiency within 60 min for Congo red and 99.1 % for methyl orange solution in 130 min owed to a large specific surface area (1.79 m2/g), reduced band gap (1.99 eV), and low recombination rate of charge carriers. The chemical mechanism for BiVO4/Ti3C2 nanocomposite proposes that Ti3C2 role-plays as electron capture because of the higher potential of MXenes, tuning band gap energy which paves the way to excellent photocatalytic action. This work opens a new basis for developing Ti3C2 based promising and inexpensive co-catalyst for efficient solar utilization in photocatalytic-related applications in the future.

β-Ni(OH)2/NiS/TiO2 3D flower-like p-n-p heterostructural photocatalysts for high-efficiency removal of soluble anionic dyes and hydrogen releasing

An ideal way to have the best of both worlds for environmental protection and energy conservation should be to juggle photocatalytic degrading pollutants and producing hydrogen from the pollutant solution synchronously. Herein, we have designed and synthesized a new 3D flower-like p-n-p heterostructure β-Ni(OH)2/NiS/TiO2 as a photocatalytic device, which is ideally suited for both removal of anionic dye methyl orange (MO), and release of hydrogen from the MO solution driven by photoelectric conversion without the need for using noble metals. The formation structure with optimal molar ratio 0.01-β-Ni(OH)2/0.001-NiS/TiO2 shows superior photocatalytic activity for removal of anionic dye MO and releasing hydrogen, its removal efficiency can reach as high as 98% in 15 min and the production of hydrogen is about 7.2 μmolh−1 from the MO solution. Results and analyses show that the outstanding performances of the sample should be attributed to the synergistic effects on two aspects. One is the high efficient charge separation and transfer driven by the internal electric field at the interfaces of NiS/TiO2 and the exposed high energy {001} facets of TiO2. The other is the modifier β-Ni(OH)2 as an assistant sacrificial agent can play an important role of the holes transfer for charge carriers transport balance in the oxidation-reduction process, and the generated active species NiOOH also has a beneficial effect on degrading MO and releasing hydrogen.

Photocatalytic degradation of methyl orange dye by Ti3C2–TiO2 heterojunction under solar light

Photocatalytic activity is a feasible solution to tackle environmental pollution caused by industrial pollutants. In this research, Ti3C2–TiO2 composite with a unique structure was fabricated successfully via a hydrothermal method. Especially, the in-situ transformation of TiO2 from Ti3C2 MXene creates an intimate heterostructure, which leads to prolonging separation and migration of charged carriers. Thus, this Ti3C2–TiO2 composite enhances effectively methyl orange (MO) degradation efficiency (around 99%) after 40 light-exposed minutes. Besides, the optimal concentration of MO solution was estimated at 40 mg/L and Ti3C2–TiO2 photocatalyst also exhibited good stability after five runs. Moreover, the radical trapping test and the MO photodegradation mechanism over Ti3C2–TiO2 system were also demonstrated. This research illustrates the potential of MXenes as effective co-catalysts for photocatalysis and extends the applications of two-dimensional materials.

Network structure-based decorated CPA@CuO hybrid nanocomposite for methyl orange environmental remediation

A unique network core–shell hybrid design-based cross-linked polyaniline (CPA), which was coated with CuO nanoparticles (NPs) and decorated with nitrogen-doped SWCNT/GO/cellulose N-SWCNTS-GO-CE, has been fabricated using the oxidative polymerization technique. This hybrid nanocomposite shows excellent photocatalytic degradation and an acceptable adsorption capability for Methyl Orange (MO) dye in aqueous solutions with a very slight effect for the N-SWCNTS-GO-CE CuO component. The prepared nanocomposites were used for the removal of a carcinogenic and noxious dye, Methyl Orange, from aqueous samples under various adsorption conditions. Approximately 100% degradation of 10 mg/L of Methylene orange dye was observed within 100 min at pH 6.0 using 50 mg/L CPA/N-SWCNTS-GO-CE/CuO nanocomposite under UV radiation. Additionally, significant factors were investigated on the degradation process including the contact time, MO initial concentration (Ci), solution pH, and dosage of the CuO nanocomposite. All investigated experiments were performed under UV radiation, which provided significant data for the MO degradation process. Furthermore, the recovery of the nanocomposite was studied based on the photocatalytic process efficiency. The obtained data provide the high opportunity of reusing CPA/N-SWCNTS-GO-CE/CuO nanocomposite for numerous photocatalytic processes. The CPA/N-SWCNTS-GO-CE/CuO nanocomposite was prepared via chemical oxidative copolymerization of polyaniline (PANI) with p-phenylenediamine (PPDA) and triphenylamine (TPA) in the presence of N-SWCNTS-GO-CE and CuO NPs. The morphology, structure and thermal properties of the CPA/N-SWCNTS-GO-CE/CuO nanocomposite were investigated using various techniques, including FTIR, XRD, RAMAN, SEM, MAP, EDX, TEM, TGA and DTG. Therefore, CPA/N-SWCNTS-GO-CE/CuO nanocomposite can be effectively used as a convenient and reusable adsorbent to remove hazardous dye from wastewater.

Enhanced Water Purification Performance of Ionic Liquid Impregnated Metal-Organic Framework: Dye Removal by [BMIM][PF6]/MIL-53(Al) Composite.

We incorporated a water-stable ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF6], into a water-stable metal–organic framework (MOF), MIL-53(Al), to generate the [BMIM][PF6]/MIL-53(Al) composite. This composite was examined for water purification by studying its capacity for methylene blue (MB) and methyl orange (MO) removal from aqueous solutions having either single dye or a mixture of both. Data illustrated that the removal efficiency and the maximum adsorption capacity of MIL-53(Al) were increased several times upon [BMIM][PF6] incorporation. For instance, within 1 min, 10 mg of pristine MIL-53(Al) adsorbed 23.3% MB from 10 mg/L of MB solution, while [BMIM][PF6]/MIL-53(Al) composite was adsorbed 82.3% MB in an identical solution. In the case of MO, 10 mg of pristine MIL-53(Al) achieved 27.8 and 53.6% MO removal from 10 mg/L of MO solution, while [BMIM][PF6]/MIL-53(Al) composite removed 61.4 and 99.2% within 5 min and 3 h, respectively. Moreover, upon [BMIM][PF6] incorporation, the maximum MB and MO adsorption capacities of the pristine MOF were increased from 84.5 to 44 mg/g to 204.9 to 60 mg/g, respectively. The adsorption of dyes in pristine MIL-53(Al) and [BMIM][PF6]/MIL-53(Al) followed a pseudo-second-order kinetic model and a Langmuir isotherm model. In a mixture of both dyes, the IL/MOF composite showed a doubled MB selectivity after the IL incorporation. The composite was successfully regenerated at least two times after its use in water purification to remove MB, MO, and their mixtures. Infrared (IR) spectra indicated that the MB/MO adsorption occurs on [BMIM][PF6]/MIL-53(Al) by electrostatic interactions, hydrogen bonding, and π-π interactions. These results showed that [BMIM][PF6]/MIL-53(Al) composite is a highly promising material for efficient water purification.

Photocatalytic Activity of TiO2 Coatings Fabricated on Al2O3 by Mechanical Coating Technique

The titanium coatings were prepared on Al2O3 balls by mechanical coating technique (MCT), and then the coatings were oxidized to titanium oxides(TiO2) films at 300–600 °C. The effects of different milling time and oxidation temperature on thickness of films were studied. The composition and microstructure of the films were analyzed by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The results show that the thickest coatings with an average thickness of 20 µm were obtained at the milling time of 15 h. In addition, with the increase of the oxidation temperature, the oxidation of the film is increased. When the milling time is 15 h, the oxidation temperature is 500 °C, and the addition of photocatalyst is 1 g/mL. The films have the best photocatalytic performance when the degradation rate of methyl orange solution reaches the maximum value of 74.9 %, and the films have a good reusability.

N-doped magnetic three-dimensional carbon microspheres@TiO2 with a porous architecture for enhanced degradation of tetracycline and methyl orange via adsorption/photocatalysis synergy

Organic contaminants in aquatic ecosystems have raised serious environmental concerns and pose severe risks to human health, and the catalytic efficiency of traditional TiO2 catalysts has been greatly limited by photogenerated electron/hole recombination. Therefore, a novel catalyst of N-doped magnetic three-dimensional (3D) carbon microspheres@TiO2 with a nanofibrous porous architecture (N-doped MCMs@TiO2) was developed from the low-cost biomass of chitin. The N-doped MCMs@TiO2 consist of N-doped carbon nanofibers, a 3D porous architecture, and a high surface area. TiO2 nanoparticles were uniformly immobilized on the N-doped carbon nanofibers, resulting in many catalytic sites. The current density of N-doped MCMs@TiO2 was approximately 0.247 uAcm−2 with 1.65 times than that of pure TiO2, and the bandgap of N-doped MCMs@TiO2 was only 1.91 eV. Additionally, N-doped MCMs@TiO2 had excellent adsorption capability for tetracycline (TC) (60.38%) and methyl orange (MO) (40.15%) in the dark after 40 min. Under the optimized conditions, N-doped MCMs@TiO2 exhibited remarkable photodegradation performance for MO and TC mixture solutions, the degradation efficiencies of MO and TC were approximately 83.80% and 74.37% under UV irradiation, and that of was maintained at 68.07% and 76.55% even in cloudy weather, respectively. Meanwhile, N-doped MCMs@TiO2 possess good potential for practical applications with long-term stability and can be easily recycled from solutions under an external magnet. Therefore, this work provides new insight into the fabrication of low-cost biomass-based 3D hierarchical porous carbon materials and that can be used as high-performance photocatalysts for the degradation of organic contaminants.

Improved Adsorption Capacity of Nannochloropsis sp. through Modification with Cetyltrimethylammonium Bromide on the Removal of Methyl Orange in Solution

In this research, biomass modification of Nannochloropsis sp. with surfactant cetyltrimethylammonium bromide (CTAB) through a cation exchange reaction to produce adsorbent Nannochloropsis sp.-cetyltrimethylammonium bromide (AlgN-CTAB) has been carried out. Biomass modification of Nannochloropsis sp. by CTAB has been successfully carried out through confirmation from the analysis data produced by Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDX). AlgN-CTAB adsorbent has been tested for its adsorption ability against anionic dye of methyl orange (MO) in solution by way of a sequence of experiments by the batch method. The optimum conditions for MO removal from the solution occurred at an adsorbent quantity of 0.1 g, pH of 5, and an interaction time of 60 min. MO adsorption kinetic data by AlgN and AlgN-CTAB tended to take the kinetic model of pseudo-second-order (PSO) with PSO rate constant ([Formula: see text]) values of 0.56 and 2.17 g mg-1 min-1, serially. The MO adsorption isotherm pattern by AlgN tends to take the Freundlich adsorption isotherm, whereas in AlgN-CTAB it follows the Langmuir and Dubinin-Radushkevich adsorption isotherms. The results of the adsorption-desorption of MO by AlgN-CTAB with 4 repetition cycles resulted in % removal of [Formula: see text]. The AlgN-CTAB adsorbent can be used repeatedly and is very effective in absorbing MO in water.

Preparation of Magnetic Composite Polyaniline/Fe3O4−Hydrotalcite and Performance in Removal of Methyl Orange

Magnetic composite fabricated from polyaniline and Fe3O4-hydrotalcite (Pan/MHT) was successfully applicated for removal of methyl orange (MO) from wastewater. The structure and properties of Pan/MHT were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, vibrating sample magnetometer, and Brunauer-Emmett-Teller adsorption isotherm. Adsorption kinetic results indicated that the adsorption process followed pseudosecond-order kinetic model ([Formula: see text]), MO adsorption onto Pan/MHT was well described by Freundlich isotherm ([Formula: see text]), and the MO adsorption capacity of 2 Pan/MHT obtained the highest with [Formula: see text]. Batch adsorption experiments were carried out using magnetic composite with the effects of initial MO concentration, solution pH, and adsorbent dosage. The results revealed that the magnetic Pan/MHT exhibited efficient adsorption of MO in the aqueous solution as a result of the affinity for organic dyes, microporous structure, and suitable surface area for adsorption (15,460 m2/g). The superparamagnetic behavior of Pan/MHT (with[Formula: see text], [Formula: see text], and[Formula: see text]) helps that it could be separated from the solution and performs as an economical and alternative adsorbent to removal and degrade azo dye from wastewater. Pan/MHT was also investigated to reuse after desorption of MO in 0.1 M HCl, and the results show that 2 Pan/MHT can be reused for 4 cycles with [Formula: see text]

Preparation and photocatalytic performance of TiO2-RGO-CuO/Fe2O3 ternary composite photocatalyst by solvothermal method

In this work, an one-step solvothermal synthesis method is used to prepare TiO2-reduced graphene oxide (RGO)-CuO/Fe2O3 ternary composite photocatalysts with TiO2 and CuO/Fe2O3 nanoparticles coated RGO, while the structures and photocatalytic performance of these synthesized ternary composite photocatalysts are studied. It is found that Cu2+ and Fe3+ are substituted for Ti4+ into the crystal lattice of anatase TiO2 in these prepared ternary composite photocatalysts. TiO2 and CuO/Fe2O3 nanoparticles are uniformly coated on the surface of RGO and closely contact with each other. The Cu/Fe doping has obviously improved the absorption ability on the visible light, and the bandgap of the ternary composite can be reduced. Under visible light irradiation, by increasing the Cu/Fe doping amount, the photocatalytic performance can be improved until the Cu and Fe contents reached 0.075 wt.% and 0.1 wt.%, respectively. The prepared products can be reused for eight cycles to degrade the methyl orange solution, and it retains over 93% photocatalytic efficiency.

Role of Nanocrystallites of Al-Based Glasses and H2O2 in Degradation Azo Dyes.

Al-based metallic glasses have a special atomic structure and should have a unique degradation ability in azo dye solutions. The Al88Ni9Y3 (Y3), Al85Ni9Y6 (Y6) and Al82Ni9Y9 (Y9) glassy ribbons are melt spun and used in degrading methyl orange (MO) azo dye solution with adding H2O2. With increasing cY, the as-spun ribbons have an increasing GFA (glass formability) and gradually decreased the degradation rate of MO solution. TEM (transmission electron microscopy) results show that the Y3 ribbon has nano-scale crystallites, which may form the channels to transport elements to the surface for degrading the MO solution. After adding H2O2, the degradation efficiency of Al-based glasses is improved and the Y6 ribbon has formed nano-scale crystallites embedded in the amorphous matrix and it has the largest improvement in MO solution degradation. These results indicate that forming nano-scale crystallites and adding H2O2 are effective methods to improve the degradation ability of Al-based glasses in azo dye solutions.

In-air proton beam irradiation induced radiolysis of methyl orange in aqueous solution

Proton irradiation induced radiolysis of methyl orange was investigated in aqueous solution with an in-air ion beam setup. 566–3024 keV energy protons were used for the irradiations of 1.6 mM aqueous methyl orange solutions, in the presence and absence of tert-butanol radical scavenger. The decoloration of methyl orange was followed by UV/vis spectrophotometry. It was found that the methyl orange can be efficiently decolorized in the applied energy range, caused by degradation processes. Furthermore, the efficiency of methyl orange radiolysis was found to be dependent on the applied proton energy. The irradiations were also carried out in the presence of 0.16 and 0.73 mol dm−3 tert-butanol using 3024 keV protons. It was found, that at lower concentration of radical scavenger the degradation was less efficient, while at higher concentration of the radical scavenger, interestingly, the degradation was more efficient when compared to the scavenger-less irradiation experiments. Initial G-values were determined for all ion energies and for different scavenger concentrations.