Degradation Rate Of Methyl Orange Research Articles

Synthesis and Visible Light Catalytic Performance of BiOI/Carbon Nanofibers Heterojunction

Semiconductor materials as photocatalysts hold great prospects for renewable energy substitutes and environmental protection. Nanostructured BiOX (X=Cl, Br, I) with favorable features of a unique layered crystal structure and suitable band gaps has been demonstrated to be a promising photocatalytic material. In this paper, a two-step synthesis route combining an electrospinning technique and SILAR reaction has been accepted as a straightforward protocol for the exploitation of BiOI/carbon nanofibers’ (CNFs) hierarchical heterostructures. As expected, the BiOI/CNFs presented a much higher degradation rate of methyl orange than that of the pure BiOI under visible light. The degradation rate of methyl orange reaches 85% within 210 min. The enhanced photocatalytic activity could be attributed to the fact that conductive CNFs as substrate could effectively improve the separation and transformation of photogenerated charges. Moreover, the fabricated BiOI/CNFs after five cycles could be easily recycled without a decrease in photocatalytic activity due to their ultra-long one-dimensional nano-structural property.

Preparation and photocatalytic properties of Bi2MO6 (M =W, Mo) semiconductor composite TiO2 nanowires

Photocatalytic degradation of pollutants using nano-TiO2 is one of the most promising strategies to solve environmental pollution problems. In this paper, we systematically studied Bi2WO6 composited TiO2 nanowires to obtain the optimum composite proportion. Moreover, the TiO2 nanowires were composited with Bi2MoO6 and Bi2WO6/ Bi2MoO6 in the optimum proportion, respectively. The results showed that the Bi2WO6/ Bi2MoO6 composited TiO2 nanowires had the best catalytic performance, and the degradation rate of methyl orange reached 78.4%, which was 3.41 times higher than that of pure TiO2 nanowires. The current work is expected to provide new ideas for the research and development of high-efficiency photocatalytic materials.

Nanoflower-like BiOBr/TiO2 p-n heterojunction composites for enhanced photodegradation of formaldehyde and dyes

A nanoflower-like BiOBr/TiO 2 p-n heterojunction photocatalyst was constructed and the possible photocatalytic mechanism was proposed. The construction of BiOBr/TiO 2 p-n heterojunction can significantly enhance the degradation of methyl orange (MO) and gaseous formaldehyde (HCHO) by photocatalysts. • A efficient nanoflower-like p-n heterojunction photocatalyst BiOBr/TiO 2 was prepared by simple solution coprecipitation. • This catalyst has enhanced photocatalytic degradation of dyes and formaldehyde. • P-n heterojunction effectively separates photogenerated carriers of BiOBr, hindering recombination of electrons and holes. The fabrication of p-n heterojunction is a smart strategy to improve the photocatalytic activity, because p-n junction can effectively promote the separation of photogenerated charges and improve the photocatalytic performance. Herein, a low cost nanoflower-like p-n heterojunction photocatalyst BiOBr/TiO 2 (abbreviated as BT-x) was prepared by simple solution coprecipitation method. Under visible light, BiOBr/TiO 2 p-n heterojunction photocatalyst showed enhanced photocatalytic activity in the degradation of Methyl Orange (MO) and gaseous formaldehyde (HCHO). The degradation rates of MO and HCHO by optimized composite BT-0.6 were 97% and 60% respectively. The p-type BiOBr with narrow band gap can effectively improve the visible light absorption, and its p-n heterojunction with TiO 2 can significantly improve the separation efficiency and transfer rate of photogenerated electron hole pairs. Meanwhile, multi-dimensional nanoflower structure is not only conducive to light reflection and improve light utilization, but also can expose more catalytic active sites. This p-n heterojunction composite material can be used as a new and promising catalyst for environmental applications.

Preparation of Pie-Shaped CoMoO4 with High Capacitive and Photocatalytic Properties by a Solvothermal Method

This paper reports a method for fabricating pie-shaped CoMoO4 nanomaterials. The morphologic characterization and phase analysis showed that the prepared material was CoMoO4 and presented a pie-shape. Pie-shaped CoMoO4 electrode materials possess high specific capacitance in three-electrode electrochemical measurement systems. When the current density is 1 A/g, the specific capacitance reaches 1902 F/g. In addition, it has good cycle stability. With 10,000 charge–discharge cycle experiments at a current density of 15 A/g, pie-shaped CoMoO4 has a specific capacity retention ratio of 99.5%. In addition, the CoMoO4//CNTs device can provide a maximum energy density of 55.6 Wh/kg (1 A/g) and a maximum power density of 10,900 W/kg (15 A/g), showing good electrochemical performance. The photocatalytic properties of pie-shaped CoMoO4 were also studied. The results show that the degradation rates of MO (methyl orange), MB (methyl blue), and CR (Congo red) can reach 97.8%, 98.8%, and 99.6% at 100 min, 40 min, and 65 min, respectively. The material has good photocatalytic performance. The excellent performance of pie-shaped CoMoO4 indicates that the electrode material has potential application scenarios in electrode materials and photocatalysis.

Copper nanoparticles-modified Na0.5Bi4.5Ti4O15 micron-sheets as a highly efficient and low cost piezo-photocatalyst

The coupling of piezoelectric effect and metal surface modification is an effective way to improve photocatalytic performance. Herein, we prepared a new piezoelectric heterojunction catalyst by depositing Cu nanoparticles on the surface of lead-free Na0.5Bi4.5Ti4O15 (NBT) piezoelectric micron-sheets. Under the simultaneous excitation of light and stirring, NBT@6.4 wt%Cu photocatalyst exhibits excellent piezo-photocatalytic activity, in which the degradation rate of methyl orange (MO) solution can reach 96% within 120 min, and the rate constant kobs value is as high as 24.67 × 10−3 min−1, which is ∼ 13 times larger than that of pure NBT photocatalyst under the excitation of light. The improved piezo-photocatalytic performance is attributed to that the deposition of Cu nanoparticles and the high piezoelectric properties of NBT facilitates the transfer and separation of photogenerated carriers. This work provides a new option for designing high-performance piezo-photocatalysts for pollutant treatment.

Titanium Dioxide–Reduced Graphene Oxide Composites for Photocatalytic Degradation of Dyes in Water

Dye wastewater due to industrialization, urbanization and academic activities has become one of the most important environmental issues today. Photocatalytic degradation technology is considered as a promising technology for treating dye wastewater due to its advantages of environmental protection and low energy consumption. Herein, titanium dioxide–reduced graphene oxide composites (TiO2-RGO) were prepared by a one-step hydrothermal method to degrade different dyes (methyl orange, methylene blue and rhodamine B) in water. The structure and morphology of TiO2-RGO were characterized using various technical approaches. The degradation effect of TiO2-RGO on the dye was in accordance with a first-order kinetic reaction. The degradation rate of TiO2-6%RGO for methyl orange at 15 min was 1.67 times higher than that of TiO2, due to the strong electron transport ability and excellent adsorption properties of graphene. TiO2-6%RGO has better degradation performance for fluorescent dyes and anionic azo dyes. Notably, the degradation rate of methyl orange by TiO2-6%RGO photocatalysis for 90 min could reach 96.9%. Meanwhile, the TiO2-6%RGO showed excellent reusability, as the initial degradation rate of 93.2% was maintained after five degradation cycles of methyl orange solution. The present work provides a universal strategy for designing efficient photocatalytic materials.

Green and reusable Ag/AgCl-TiO2 nanocomposites for visible light-triggered dye degradation

• Ag/AgCl-TiO 2 nanocomposites are synthesized in a green, single-step process. • Satureja khuzistanica extract acts as a reducing agent and nanocomposite stabilizer. • More than 99% methyl orange is degraded under visible light irradiation. • High-efficiency TiO 2 -based photocatalysts developed for engineering and environmental applications. Ag/AgCl-TiO 2 plasmonic nanocomposites (NCs) are endowed with excellent visible-light photocatalytic activity. However, only a few studies investigated environmentally friendly approaches to their synthesis. In this work, Ag/AgCl-TiO 2 NCs at five different compositions were prepared in a single-step process by a green and cost-effective route, using Satureja khuzistanica Jamzad aqueous extract. The role of the aqueous plant extract as a reducing and stabilizing agent, and the formation of the NCs were evidenced by several techniques, including FT-IR, EDS, SEM, HRTEM, elemental mapping, and XRD. The morphological analysis demonstrated that the NCs formed nanoaggregates with an average size of 30 nm. The synthesized Ag/AgCl-TiO 2 NCs displayed a remarkable photoactivity in the visible light region, as confirmed by the significantly higher degradation rates of methyl orange (MO) compared to TiO 2 . In particular, the 15% Ag/TiO 2 molar ratio sample revealed a MO degradation efficiency higher than 99% under visible light, and retained high photocatalytic activity even after several degradations runs. Overall, the green, cost-effective, and scalable synthesis of Ag/AgCl-TiO 2 NCs herein reported provides a novel, more sustainable strategy for the high-efficiency modification of TiO 2 photocatalyst in engineering and other environmental applications.

Study on photocatalytic and mechanical properties of TiO2 modified pervious concrete

Photocatalytic pervious concrete pavement is a potential and sustainable new method for treating urban air and water pollution, and there is now an increasing amount of research on TiO2 pervious concrete due to its excellent photocatalytic properties. In this study, pervious concrete with varying nano-TiO2 contents (0 %, 1 %, 2 %, 5 %, 8 %) was prepared and evaluated for its performance in purifying methyl orange (MO). The results show that as the TiO2 content increased from 0 % to 8 %, the photocatalytic degradation efficiency increased and then decreased, with the highest MO degradation rate of pervious concrete with 5 % TiO2 content was 42.8 % at 120 min. However, as the TiO2 content increases, the compressive strength and TiO2 utilization rate of pervious concrete gradually decrease, and the 28-day compressive strength decreases from 26.0 MPa to 13.5 MPa. Therefore, 2 % TiO2 content was determined to be optimal for pervious concrete.

Preparing Cu2O/Al2O3 Coating via an Electrochemical Method for the Degradation of Methyl Orange in the Process of Catalytic Wet Hydrogen Peroxide Oxidation

To improve the catalytic efficiency and decrease the reaction temperature of wet air oxidation technology, a Cu2O/Al2O3 coating was prepared on the surface of aluminium alloys by anodizing technology, and subsequent heating treatment. Then, the Cu2O/Al2O3 coating and 3 wt.% H2O2 was used to degrade methyl orange. The influence of the coating’s microstructure, crystalline component on the degradation rate of the methyl orange was studied. The microstructure of the coating was observed by scanning electron microscope. Results proved that the coating was composed of micropores, and Cu2O was evenly dispersed on the surface and pores in the Al2O3 coating. X-ray diffraction pattern analysis demonstrated Cu2O and Al2O3 characteristic peaks were found after the coating was treated at 300 °C, showing that amorphous Cu2O and Al2O3 were transformed into crystalline oxide. A UV-vis spectrophotometer was used to measure the absorbance of methyl orange, and it was found that the maximum absorption wavelength of methyl orange is 460 nm. At that wavelength, the suitable degradation condition of methyl orange was studied, and results showed that when electrochemical deposition time was 30 min and catalyst dosage was 8 g, the degradation rate of methyl orange could reach 92% at 25 °C for 120 min. Furthermore, when the catalyst was reused 9 times, the degradation rate still reached 75%. Based on the above results, a kinetic equation between the degradation rate of methyl orange and catalyst dosage was derived. The microstructure and crystalline component of the catalyst after different reuse times were characterized, and results showed that the catalytic efficiency of the Cu2O/Al2O3 coating decreased with a decrease in the coating’s specific surface area and the ratio of Cu2O in the coating.

Facet-dependent Cu2O@Zn(OH)2 composites with enhanced visible-light photocatalysis

Facet-dependent Cu2O@Zn(OH)2 composites were synthesized by wrapping morphology-controllable Cu2O crystals (cubic, cuboctahedral and octahedral) with the adsorbent Zn(OH)2 nanosheets. The cuboctahedral Cu2O@Zn(OH)2 composite exhibits the highest photocatalytic performance than cubic and octahedral ones with the degradation rate of methyl orange up to 96.6% under visible-light irradiation due to the best crystal facet-dependent photocatalytic performance of cuboctahedral Cu2O. Moreover, the presence of Zn(OH)2 nanosheets can enhance the rapid adsorption of dye molecules, and thus accelerate the photocatalytic process. The combination of Zn(OH)2 nanosheets with physical adsorption capacity and facet-dependent Cu2O crystals with catalytic performance effectively enhances the photocatalytic performance of composite catalyst.

Enhanced degradation of organic pollutants by MnCo2O4.5/formic acid process: Active species and mechanism

• The MnCo 2 O 4.5 /formic acid system led to high oxidation of Methyl Orange. • Mn(III) was found to be the active species for organic pollutant degradation. • The degradation rate of MO was 92.7% in 30 min. • This study might lead to a novel advanced oxidation technology. A system of MnCo 2 O 4.5 catalyst/formic acid is proposed for the degradation of methyl orange (MO). The degradation rate of MO reached 92.7% in MnCo 2 O 4.5 /formic acid process. The efficient degradation of MnCo 2 O 4.5 /formic acid system was based on oxidation by Mn(III).

Ce2(MoO4)3 synthesized with oleylamine and oleic acid as additives for photocatalysis: effect of preparation method.

Ce2(MoO4)3 was prepared using dielectric barrier discharge (DBD) plasma method, co-precipitation method and hydrothermal method, respectively, with water/ethanol (W/O) as solvent, oleylamine (OAm) and oleic acid (OAc) as additives. Preparation method showed significant influence on the morphological and structural properties, as well as photocatalytic performance. Ce2(MoO4)3 synthesized with DBD plasma (MO-P) was mainly flowerlike nanosheets, which were beneficial to promoting electron transfer and providing more space for catalytic activity. Also, MO-P samples exhibited more oxygen vacancies, which were conducive to the photocatalytic performance. What's more, MO-P showed lower PL intensity and narrow energy gap, which implied a slow photoelectron-hole pair recombination rate and an increased electron transfer rate. The degradation rate of methyl orange (50mg/L) could achieve 98% within 12min with 0.5g/L MO-P. Hydroxyl radicals (·OH) and superoxide radicals (·O2-) played a major effect. Plasma synthesis method exhibited potential application prospect in photocatalysts preparation.

Role of conductive channels via CQDs on NiO/g-C3N4 Z-scheme composite as a bi-functional photocatalyst

Herein, an innovative graphitic carbon nitride (g-C3N4) based nanocomposite with nickel oxide (NiO) is modified with carbon quantum dots (CQDs) to fabricate CQD/NiO/g-C3N4 ternary composites. The effect of various concentrations of CQDs is investigated for photo electrochemical (PEC) water splitting and photocatalytic degradation of methyl orange (MO). XRD pattern of CQDs/NiO/g-C3N4 composite showed the distinctive peaks of g-C3N4 and NiO. The reduction of band-gap values from 2.62 to 1.8 eV in UV–Visible spectra of nanocomposites confirmed an improvement toward red shift. The existence of required functional groups and successful fabrication of nanosheets of g-C3N4 and its nanocomposites are confirmed by FTIR. PL confirms the decrease in electron-hole recombination in binary and ternary composites. CQDs/NiO/g-C3N4 (4.0 mL) showed enhanced PEC activity and photocatalytic performance in visible light exposure. CQDs/NiO/g-C3N4 (4.0 mL) showed an obvious enhancement in current density of ∼-19 mAcm−2 at potential 0.39 V during hydrogen evolution reaction (HER) and high current density of ∼ 15 mAcm−2 at 1.42 V in oxygen evolution reaction (OER) than all others. The highest degradation rate of MO by CQDs/NiO/g-C3N4 (4.0 mL) was noted due to availability of plenty of active sites and conductive channels provided by CQDs. Incorporated CQDs in samples affect the overall water splitting response and photocatalytic activity by acting as electron conduction bridge for the quick electron transfer from the composite materials to reaction sites on its surface. This combination is active for efficient PEC water splitting and photo degradation purposes.

Facile synthesis of Z-scheme ZnMoO4/Bi2O4 heterojunction photocatalyst for effective removal of levofloxacin

• A possible mechanism of ZnMoO 4 /Bi 2 O 4 Z-scheme heterojunction is proposed. • Levofloxacin and methyl orange were used to evaluate the photocatalytic activities. • The separation of photoinduced carriers was testified by photocurrent, PL and SPV. • HAADF-STEM, ESR and Mott-Schottky analysis were used to analyze the mechanism. A new Z-scheme ZnMoO 4 /Bi 2 O 4 heterojunction was successfully prepared by a hydrothermal method, and the optimal ratio was determined by regulating the concentration of ZnMoO 4 . The experimental results indicated that the ZMB-15 heterojunction (the molar ratio of Zn/Bi is 0.15:1) exhibited the best photocatalytic activity for the degradation of methyl orange and levofloxacin under visible-light irradiation due to the effective separation of electron-hole pairs at the interface. The degradation rates of methyl orange (15 mg/L) and levofloxacin (15 mg/L) reached 93.80% and 85.24%, respectively. The five-cycle experiments proved that the ZMB-15 catalyst was stable and highly reusable. In addition, three active species, h + , OH, and O 2 – , played dominant roles in the photodegradation of organic pollutants. Based on the above analysis, a mechanism for the Z-scheme ZMB-15 heterojunction was proposed.

Novel alginate immobilized TiO2 reusable functional hydrogel beads with high photocatalytic removal of dye pollutions

Abstract TiO2 semiconductor photocatalysis is an effective technology for the treatment of wastewater containing organic dye pollutants, which has been received extensive focus. However, the problems in the recovery and reutilization process impede the large-scale applications of particulate photocatalytic materials. Herein, a macro sized hydrogel bead loaded with nano TiO2 powder was successfully prepared by taking advantage of the cross-linking and gel property of alginate salt, which could form egg-box structure naturally when Na+ ions in sodium alginate (SA) were replaced by divalent ions such as Cu2+, Co2+, and Sr2+ ions. The photocatalytic degradation rate of methyl orange (MO) solution in the presence of the hydrogel beads reaches 99% within 60 min under the ultraviolet light irradiation, which is competitive with that of TiO2 nano powder. Furthermore, the hydrogel beads prepared by this strategy maintain over 95% photocatalytic degradation rate after 10 cycles of degradation process. The results indicate that the network structure of alginate could immobilize and disperse TiO2 particle effectively, and it is readily for the spherical beads to contact and harvest the light, making the alginate beads have excellent photocatalytic functions. Also, the alginate based beads integrate good performance with high stability and excellent recyclability perfectly.

An Ultrasound Application for TiO2 Photocatalytic Degradation of Methyl Orange

Nanometer TiO2 photocatalysts were prepared by the sol–gel method. The catalysts were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and other techniques. Methyl orange solution was used for the degradation of the organic material and ultrasonic technology was used to determine the photocatalytic performance of the catalysts. The results show that the photocatalytic performance of the Ni-N-TiO2 is clearly improved under ultrasonic conditions. The TiO2 photocatalytic degradation effect is optimal at a catalyst concentration of 0.3 g/L, an initial concentration of the organic matter of 0.03 mmol/L, a nickel-doping amount of 2 mol %, and a nitrogen-doping amount of 15 mol %. The use of ultrasound technology in combination with photocatalysis has a positive effect and results in a TiO2 degradation rate of methyl orange of 95 % after 3 h.

Composite Nanoarchitectonics of LaNi0.95Fe0.05O3/Muscovite for Enhanced Photocatalytic Activity

AbstractPowder-type semiconductor photocatalysts are widely applicable but their defects (e.g. easy agglomeration during preparation and recyclability in the suspension system) limit their practical application. In the current study, perovskite oxide photocatalytic material was loaded onto a muscovite substrate to overcome the problems of low stability, easy agglomeration, and difficult recovery. A photocatalytically active LaNi0.95Fe0.05O3/muscovite composite material was synthesized by a sol-gel impregnation method. Phase composition, morphology, and interfacial interaction of the composites, denoted as LNFBY-x (x: mass ratio of LNF to muscovite), were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and other analytical methods. According to the results, the particle size of LNF nanoparticles was regulated effectively by compounding with muscovite, and the agglomeration of LNF decreased. LNF nanoparticles were distributed evenly and attached in dense fashion to the surface of muscovite, thereby increasing the contact area with the reaction medium. The nanoparticles were connected to the silicon-oxygen tetrahedral sheet of the muscovite via Si–O–La, Si–O–Ni, and Si–O–Fe bonds, which increased the bonding strength between the composite components and expedited the transfer of photogenerated charge. More highly active oxygen species were produced, and a growing number of chemically active moieties (٠O2- and ٠OH) was generated in the photocatalytic reaction. LNFBY-1.00 demonstrated the best photocatalytic activity. A degradation rate of methyl orange of 99.03% was achieved after visible-light irradiation for 120 min, which decreased to 75.75% after five repeated uses, thereby indicating high stability and recycling ability. The photocatalytic LaNi0.95Fe0.05O3/muscovite composite material exhibited potential for application in environmental remediation practices.

Facile synthesis of Ag/AgCl/3D-rGO with rapid catalytic degradation toward Methyl Orange and Rhodamine B

Ag/AgCl/3D-rGO is facilely synthesized by a mild method, and the resulting composite catalyst is systematically characterized by means of Scanning Electron Microscope, Energy Dispersive Spectrometer, Raman Spectra, X-Ray Photoelectron Spectroscopy and X-Ray Diffraction. The characterization result shows that Ag/AgCl nanoparticles are homogeneously dispersed throughout the sheet surface of the block graphene oxide. The catalytic activity of the resulting composite is assessed by the degradation of Methyl Orange (MO) and Rhodamine B (RhB) in the presence of sodium borohydride. The pseudo-first order kinetic study shows that Ag/AgCl/3D-rGO possesses outstanding catalytic degradation activity toward both MO and RhB. The degradation rates of MO and RhB can reach 92 % and 98 % in 15 min, respectively, indicating the rapid catalytic performance of the resulting Ag/AgCl/3D-rGO in the presence of sodium borohydride. In addition, the possible formation and dyes degradation mechanism of Ag/AgCl/3D-rGO are also proposed. The excellent catalytic activity reveals that Ag/AgCl/3D-rGO may have a promising potential application in organic dye wastewater treatment.

Synergetic piezo-photocatalytic effect in SbSI for highly efficient degradation of methyl orange

SbSI nanowires (SbSI NWs) and SbSI microrods (SbSI MRs) were synthesized by simple sonochemical and hydrothermal methods, respectively. The SbSI NWs possess better catalytic performance due to the smaller size and larger specific surface area. Meanwhile, the piezoelectric effect and photocatalytic performance of SbSI were combined for the first time. The degradation rate of methyl orange (MO) solution (30 mg/L) by SbSI NWs reaches 97.1% within 2 min under the synergistic effect of visible light and ultrasonic vibration, which is 4.83 times of photocatalysis and 14.22 times of piezocatalysis. The reactive oxide species (ROS) such as hydroxyl radicals (•OH) and superoxide radicals (•O2−) were examined by radical trapping experiments to demonstrate their critical role in degrading MO molecule. Furthermore, a possible mechanism of the piezo-photocatalytic process was proposed and degradation pathway of MO dyes by SbSI NWs was suggested based on the HPLC-MS results. It shows that the degradation process of MO includes the breakage of azo double bond, the removal of sulfonic group, the breakage of carbon nitrogen bond, and finally the formation of NO3−, SO42−, CO2 and H2O. This work provides a promising case for the practical application in dye wastewater treatment of piezoelectric semiconductors.

Photocatalytic degradation of methyl orange on ZnO–TiO2/SO42− heterojunction composites

ZnO–TiO2/SO42− (ZTOS) heterojunction composites were prepared by an inorganic precipitation-peptization method. It is found that the molar ratios of Zn : Ti have obvious influence on the ultraviolet (UV) light absorption and morphology of ZTOS. The results of photocatalytic characterizations indicate that the degradation rate of methyl orange on ZTOS (90.34%) is significantly higher than that of on the pure TiO2 (43.58%). In addition, the ZTOS can holds 97% photocatalytic activity after cyclic stability measurements. The remarkable improved performance obtained on ZTOS is attributed to the stronger UV light absorption, large specific surface area and effective charges separation caused by the heterojunction structure of ZnO–TiO2. Furthermore, the active species for the decomposition of methyl orange on ZTOS are proposed to be the photo-generated holes and radicals of ·O2−, ·OH and SO4−· formed during photo-induced reactions.