Activity For Methylene Blue Degradation Research Articles

Synthesis of flower-like CuS/reduced graphene oxide (RGO) composites with significantly enhanced photocatalytic performance

The flower-like CuS/RGO composites were fabricated via a facile one-step solvothermal method, which displayed outstanding photocatalytic activity for MB degradation. The composition and structure of the prepared composites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra, photoluminescence (PL) spectra, scanning electron microscopy (SEM) and UV–vis optical absorption spectroscopy. The results showed that RGO had significantly influence on the photocatalytic performance. Compared with pristine CuS, flower-like CuS/RGO composites exhibited enhanced photocatalytic activity and excellent recyclability for the photodegradation of Methylene blue (MB) with degradation efficiency of nearly 100% in 140min under Xenon lamp irradiation, which was 4 times greater than that of CuS, indicating that CuS/RGO could be acknowledged as a promising photocatalyst for the removal of organic contaminants.

Photocatalytic activities of sulfur doped SrTiO3 under simulated solar irradiation

S-doped SrTiO3 was synthesized by the solid state reaction method between S and SrTiO3 power under the N2 flow. The effect of temperature, calcination time and S-content on the formation and photocatalytic activity of SrTiO3 were investigated. The morphology and properties of obtained powders were characterized by XRD, UV-DRS, UV-VIS, SEM, BET. The photocatalytic activities of S-doped SrTiO3 was also investigated through the decomposition of methylene blue. As a result, the 10 %S-doped SrTiO3 contributed to the decrease of band gap energy to 2.73 eV and enhanced the photocatalytic activity for methylene blue degradation of 74.5 % after 180 min irradiation.

ZnO<sub></sub>/VNC Material for UV-Photodegradation of Methylene Blue

ZnO materials act as a Photocatalytic reaction and it leads to partial or complete mineralization or decolorization of organic pollutants. Upon irradiation with UV/visible light, semiconductors catalyze undergoes redox reactions in presence of air/O2 and water. In the present study Zinc oxide (ZnO) was doped with activated carbon prepared from the stem of the plant material by chemical activation namely, Vitexnegundo stem carbon (VNC). The decolourisation and degradation study of a dye namely, methylene blue (MB) was carried out to find out the efficiency of catalytic property of ZnO/VNC. The reaction was performed at 20, 40, 60 ppm of dye solution with ZnO/VNC material at 10 min interval of time. It found that the prepared ZnO / VNC composite exhibits an enhanced Photocatalytic activity for MB degradation under visible light irradiation and its photo catalysis efficiency was analyzed in specific 663 nm λ max using a UV–vis-spectrophotometer. The surface morphology and functional group present in the ZnO / VNC material was characterized by using FT-IR, SEM and XRD. The result reveals that the ZnO/VNC structure consists of irregular aggregates with rough surfaces and high photodegradation activities of ZnO/VNC on MB solutions are found to be at 20ppm. The ZnO/VNC may be used as an alternative adsorbent to remove MB from aqueous solutions.Keywords: Methylene blue (MB), ZnO / VNC, FT-IR, SEM, XRD

Remarkably enhanced photocatalytic activity by sulfur-doped titanium dioxide in nanohybrids with carbon nanotubes

TiO2 doped S nanohybrids with carbon nanotubes (CNTs) were synthesized with CNTs, thiourea and TiO2 nanoparticles. The result indicated that the TiO2 nanoparticles with about 8nm in size are attached on the sidewall of CNTs. The nanohybrids material can absorb at longer wavelength and the absorption even covers the whole range of visible region than that only TiO2 nanoparticles. Application of the catalysts to photocatalytic degradation of methylene blue (MB) was tested under visible light irradiation. The result suggests that a high MB degradation activity of S-TiO2/CNTs due to a reduce band gap of TiO2 when S is doped, and the decrease in the possibility of electron–hole recombination by CNTs. In addition, the density functional-theory (DFT) calculations of the electronic band structures and density of states (DOS) to understand the bonding states between TiO2 and CNTs, proved that the TiO2/CNTs system is stable.

ZnO<sub></sub>/VNC Material for UV-Photodegradation of Methylene Blue

ZnO materials act as a Photocatalytic reaction and it leads to partial or complete mineralization or decolorization of organic pollutants. Upon irradiation with UV/visible light, semiconductors catalyze undergoes redox reactions in presence of air/O2and water. In the present study Zinc oxide (ZnO) was doped with activated carbon prepared from the stem of the plant material by chemical activation namely,Vitexnegundostemcarbon (VNC). The decolourisation and degradation study of a dye namely, methylene blue (MB) was carried out to find out the efficiency of catalytic property of ZnO/VNC. The reaction was performed at 20, 40, 60 ppm of dye solution with ZnO/VNC material at 10 min interval of time. It found that the prepared ZnO / VNC composite exhibits an enhanced Photocatalytic activity for MB degradation under visible light irradiation and its photo catalysis efficiency was analyzed in specific 663 nm λ max using a UV–vis-spectrophotometer. The surface morphology and functional group present in the ZnO / VNC material was characterized by using FT-IR, SEM and XRD. The result reveals that the ZnO/VNC structure consists of irregular aggregates with rough surfaces and high photodegradation activities of ZnO/VNC on MB solutions are found to be at 20ppm. The ZnO/VNC may be used as an alternative adsorbent to remove MB from aqueous solutions.Keywords: Methylene blue (MB), ZnO / VNC, FT-IR, SEM, XRD

Role of ZnO on nylon 6 surface and the photocatalytic efficiency of methylene blue for wastewater treatment

Nylon 6 and its modification as a compound have been employed in several applications such as in the textile industry. To gain effectiveness in textile applications, nylon 6’s self-cleaning and antibacterial properties were modified. ZnO was successfully synthesized using a wet chemical synthetic procedure. The thermal decomposition of the ZnO precursor was investigated using thermogravimetric analysis. The calcination temperature was set to be 500–1000 °C for 2 h. Decomposition products of the organic phase were removed at temperatures ranging from 300 to 500 °C. X-ray diffraction and scanning electron microscopy showed the single phase of ZnO and the variable-sized hexagonal-shaped cross-section, respectively. With incremental increases in the calcination temperature, there was no residue from char, and agglomeration of the ZnO increased. The ZnO was dispersed in methanol and subsequently spin-coated onto a nylon 6 surface. The efficiency of ZnO coating on the nylon 6 surface was investigated by the photocatalytic activity of methylene blue degradation. The apparent rate constant was estimated to be 0.5 by the Langmuir-Hinshelwood equation. The photocatalytic activity of ZnO coated on nylon 6 exhibited excellent performance for wastewater treatment in the textile industry.

Integrated oxygen-doping and dye sensitization of graphitic carbon nitride for enhanced visible light photodegradation

Graphitic carbon nitride (GCN) is a promising metal-free photocatalyst while suffering from low charge mobility induced inefficient photocatalysis. In this work, oxygen doping was employed to enhance the photodegradation of organic pollutants in water on graphitic carbon nitride (GCNO) under visible light. For further absorption extension, four organic dyes (Eosin-Y, Perylene, Nile-red and Coumarin) were adopted to dye-sensitize the GCNO photocatalyst. It was found that O-doping can promote dye sensitization, which was dependent on the type of dyes and influenced the photodegradation efficiencies of methylene blue (MB) and phenol. Nile-red sensitized GCNO presented the best activity in MB degradation under λ>480nm irradiations while Eosin-Y showed the best sensitization performance for phenol degradation under λ>420nm light source. However, dye sensitization was not effective for enhanced pollutant degradation on GCN without O-doping. UV–vis diffuse reflectance spectra (UV–vis DRS), photoluminescence (PL) spectra, and photocurrent analyses were applied to investigate the mechanism of carriers’ transfer, which indicated that dye molecules could inject extra electrons into GCNO energy band and the energy dislocation could suppress electron/hole recombination, enhancing photocatalytic performances.

Study on Green Synthesis of Gold Nanoparticles and Their Potential Applications as Catalysts

Gold being the most biocompatible metal nanoparticle has become an important biosynthesized drug to be studied in recent field of bioscience. The fungus Aspergillus fischeri has been isolated from fruit crop and thus exploited for the synthesis process. Synthesized GNPs were characterized by UV–visible spectroscopy showed absorption spectra in the range of 530–550 nm at different concentrations of HAuCl4. At the optimum reaction concentration of 1 mM HAuCl4, absorption peak was obtained at 543 nm. The GNPs have been further characterized by X-ray diffraction, FTIR, DLS and TEM analysis. The DLS graph showed that the particles were monodispersed. The TEM image showed the formation of spherical shaped GNPs in the range of 50 nm which was in accordance of the particle size analysis by DLS. The potential applications of the gold nanoparticles are yet to be explored and thus, we have conducted a time dependent comparative catalytic activity for methylene blue degradation of chemically synthesized and biosynthesized GNPs which showed biosynthesized ones are better catalysts than chemical ones.

Facile synthesis of carbon-Bi2WO6 with enhanced visible-light photocatalytic activities

Bi2WO6 doped with different amounts of carbon were synthesized using hydrothermal method, and their photocatalytic activities for methylene blue degradation under visible-light irradiation were investigated. The prepared samples were characterized by SEM, EDX, DRS, PL, Raman, and EPR measurements. The results suggest that carbon doping has great influences on the visible-light-driven photocatalytic activity of Bi2WO6 as well as its microstructure. The 1.5C-Bi2WO6 hybrid material shows the highest activity, resulting in a 98 % degradation ratio of MB within 3 h under visible-light irradiation. It is further confirmed by photocurrent generation and electrochemical impedance spectral measurements. The present research provides a simple and valid method for improving the visible-light-responding photocatalytic activity and fabricating different morphologies of Bi2WO6. Combined Bi2WO6 with carbon could change the flower structure and size of the Bi2WO6 catalyst. The resulting 1.5C-Bi2WO6 flake has strong absorption in the visible-light region and have obviously enhanced photocatalytic activities for the degradation of MB. The photocurrent catalytic activity of the Bi2WO6 flake was almost 15 times higher than that of Bi2WO6.

In situ loading of CuS nanoflowers on rutile TiO2 surface and their improved photocatalytic performance

CuS nanoflowers, fabricated by an element-direct-reaction route using copper and sulfur powder, were loaded on rutile TiO2 (CuS/TiO2) at low temperature. CuS/TiO2 composites were utilized as the photocatalysts for the degradation of Methylene Blue (MB) and 4-chlorophenol (4-CP). X-ray diffraction (XRD), UV Raman spectroscopy, transmission electron microscopy (TEM), XPS, and UV-visible diffuse reflectance spectra were used to characterize the crystalline phase, morphology, particle size, and the optical properties of CuS/TiO2 samples. It is found that CuS/TiO2 photocatalyst, which CuS are loaded on the surface of rutile TiO2, exhibited enhanced photocatalytic degradation of MB (or 4-CP) than TiO2 or CuS. This indicates that CuS can enhance effectively the photocatalytic activity of rutile TiO2 by forming heterojunction between CuS and rutile TiO2, which is confirmed by photoluminescence (PL) spectra and TEM. Moreover, CuS content has a significant influence on photocatalytic activity and 2wt% CuS/TiO2 showed the maximum photocatalytic activity for degradation of MB.

A series of novel double perovskite oxides NaMTi2O6 (M = Eu, Sm, and Gd): preparation, characterization and photocatalytic studies under visible and solarlight irradiation

The photocatalytic activity of sol–gel synthesized double perovskite type oxides NaEuTi2O6(NETO), NaSmTi2O6 (NSTO), and NaGdTi2O6 (NGTO) powders on degradation of methylene blue (MB) dye was demonstrated for the first time under visible light as well as sunlight irradiation. The obtained samples were characterized by X-ray diffraction, UV–Visible diffuse reflectance spectroscopy and scanning electron microscopy equipped with X-ray energy-dispersion spectrometry. All the three samples have shown photocatalytic activity for degradation of MB under sunlight and visible light irradiation and their photocatalytic activity followed the order of NGTO > NETO > NSTO. The superior activity of NGTO is ascribed to the higher amount of hydroxyl radicals generated in the photocatalytic reaction.

나노 TiO<sub>2</sub>를 적용한 식품 포장 필름 개발 및 콩나물의 이취 제거

For testing the ultraviolet (UV)-blocking property of functional films coated with Nano-TiO₂ particles, UV-Vis spectra of oriented polypropylene (OPP) films uncoated and coated with TiO₂ of 3% and 5% in Polyurethane (PU) and polyvinyl butyral (PVB)-Cellulose binders were measured. The result of UV-Vis analyses showed that the film coated with 5% TiO₂ in PVB binders had a significant effect on UV protection of 90% compared with the film uncoated. Also The result of The photodegradation of methylene blue (MB), OPP films coated with 5% in both PU and PVB binders had a high photocatalytic activity for MB degradation. To evaluate the effect of the developed functional film coated with Nano-TiO₂ particles, fresh soybean sprouts were used. Nano-TiO₂ coated film was observed to decompose the off-flavor produced by soybean sprouts within packages during distribution, but uncoated film did not. Therefore, Nano-TiO₂ coated film package could give the greatest effect in extending the shelf life of soybean sprouts.

Application of TiO2 photocatalyst to the stone conservation

In this paper, we report our studies on the application of TiO2 catalyst to the stone conservation for the purpose of exploring new protective materials and methods which are compatible with the work of stone art. The sol solution of anatase TiO2 was prepared at a low temperature. The structure and microtopography of materials were investigated using X-ray diffractometer and scanning electron microscope. Acid resistance, soiling resistance, super-hydrophilicity, UV-light absorption and visible light transmittance of treated stones were carried out in order to evaluate efficiency of TiO2 catalyst as a protective agent. The TiO2 catalyst's photocatalytic activity for methylene blue degradation was also investigated in aqueous heterogeneous suspensions. The experimental results show that the TiO2 can function well as a new protective agent for stone conservation. This study indicates that the TiO2 photocatalyst has great potential as the protective material for stone conservation.

Catalytic activity of the barium hexaferrite with H2O2/visible light irradiation for degradation of Methylene Blue

Barium hexaferrite (BaFe12O19) is a novel and effective catalyst in the photo-Fenton like system for the rapid degradation of Methylene Blue (MB). The BaFe12O19 catalyst was synthesized by the chemical co-precipitation method and characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), Brunauer–Emmet–Teller (SBET) surface area and optical adsorption analysis. The BaFe12O19 catalyst generated a good catalytic activity for MB degradation for a photo-Fenton like system under visible light irradiation, this is possible due to the catalyst can be activated using photons of visible light region as a consequence of its narrow band gap estimated of ∼1.77eV, corresponding to absorption edge in the visible region from a wavelength of ∼700nm. In such conditions the BaFe12O19 was able to decolorize and to mineralize up to 70.8% and 63.7% of the dye, respectively, after 360min using a 3W Light Emitting Diode (LED) lamp (λ=420–700nm). In addition, the energy consumption of the Vis/BaFe12O19/H2O2 system was estimated at 11.1Wh/L/order.

Facile synthesis of spinel CuCr2O4 nanoparticles and studies of their photocatalytic activity in degradation of some selected organic dyes

Copper chromite (CuCr2O4) spinel nanoparticle catalysts have been successfully synthesized employing urea assisted co-precipitation followed by calcination. The synthesized nanoparticles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and N2 adsorption-desorption isotherm (BET). The XRD pattern revealed formation of tetragonal body-centered CuCr2O4 and TEM image showed quasi-spherical particles of size 5–35 nm. The photocatalytic activity of CuCr2O4 was evaluated in degradation of some organic dyes such as methylene blue (MB), methyl orange (MO), and rhodamine B (RhB), without and with the assistance of H2O2 under solar irradiation. The CuCr2O4 photocatalysts showed high activity in degradation of RhB (93.6%) and MO (92.3%), but low activity in degradation of MB (80.6%). The catalyst reusability was tested by conducting the degradation of RhB dye with the spent catalyst and it was observed that the catalyst did not show any significant loss in its activity even after five cycles.

Synthesis and assessment of a graphene-based composite photocatalyst

A novel composite photocatalyst prepared from graphene and commercial TiO2 (P25 from Evonik) was synthesized, exhibiting enhanced photocatalytic activity for methylene blue degradation, when compared with pristine P25. Additionally, the new catalyst showed 20% more NO conversion under UV light than P25. The band gap of the catalyst, obtained from diffuse reflectance, was 2.95eV indicating an extended light absorption up to 420nm. The novel photocatalyst was further tested for inactivating microorganisms showing better results than the reference photocatalyst. Under visible light, the viability loss of the reference bacterial strain Escherichia coli DSM 1103 was two times higher than with the bare P25; it was observed 29% of inactivation with the P25/graphene composite and 14% with the P25 sample, following standard ISO 27447:2009.

Impact of calcination atmospheres on the physiochemical and photocatalytic properties of nanocrystalline TiO2 and Si-doped TiO2

Nanocrystalline TiO2 and Si-doped TiO2 samples were prepared by solvothermal and sol–gel methods. Before the characterization and photocatalytic test, the thus-obtained powder and gel were calcined under different atmospheric gas flows (O2, air, and N2). The physiochemical properties of the samples were determined using X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–vis), electron spin resonance (ESR), transmission electron microscope (TEM), energy dispersive X-ray spectrometer (EDX) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was evaluated by the degradation of methylene blue (MB) dye under UV and visible light irradiation. The solvothermal-made N2-treated TiO2 nanocatalyst showed the highest photocatalytic activity under both UV and visible light irradiation. The addition of Si resulted in the formation of partial monolayer of Si on TiO2 nanocatalyst and an increase of the anatase phase stability. The ESR and XPS results reveal that the calcining atmosphere affected the distribution concentration of surface and interface species in TiO2 and Si-doped TiO2, such as surface oxygen and Ti3+ sites, thus improving photocatalytic activity. The increasing of anatase phase stability and the formation of Ti3+ sites due to N2-treated and Si-doped TiO2 nanocatalyst promoted the photocatalytic activity of MB degradation.

One-step synthesis of Zn doped titania nanotubes and investigation of their visible photocatalytic activity

Highly oriented undoped and Zn-doped titania (TiO2) nanotubes were electrochemically fabricated by one-step anodization of titanium foil in a freshly prepared aqueous solution of zinc fluoride (ZnF2) and ethylene glycol (EG). XRD and Raman spectroscopy unveiled the typical characteristic of anatase phase of TiO2 nanotube without any distinct dopant related peaks. SEM and AFM observation confirmed the formation of nanotubes and revealed that the Zn doping did not distort the tube morphology of TiO2. The doping of Zn was confirmed by energy dispersive X-ray as well as X-ray photospectroscopy. Due to one-step anodization process, instead of surface doping, the Zn2+ ions were incorporated into the bulk of TiO2 nanotubes. With increasing Zn doping in nanotubes, a gradual decrease in the band gap of TiO2 (2.84 eV) was observed. Photoluminescence measurements revealed that the doping of Zn enhanced the number of charge carriers, which eventually boosted the photocatalytic activity of TiO2 nanotubes. Compared to undoped nanotubes, the as prepared Zn-doped TiO2-nanotubes showed excellent photocatalytic activity for methylene blue degradation (reaction rate constant k = 0.19 min−1) under visible light irradiation.

Hydrothermal Synthesis and Enhanced Photocatalytic Activity of TiO\(_{2}\)-Fe@CNTs Nanocomposite for Methylene Blue Degradation under Visible Light Irradiation

TiO2 is one of the most attractive metal oxides because of the excellent chemical and photocatalytic properties. However, a problem in the application of TiO2 is the large band gap energy of 3.2 eV, corresponding to its photocatalytic activity under UV-light irradiation of wavelengths <387 nm. In this work, TiO2 nanoparticles doped with iron were grown on the surface of functionalized carbon nanotubes (TiO2-Fe@CNTs) to expand the photoabsorbance of the nanocomposite materials in the visible light region and improve their photocatalytic activity. TiO2-Fe@CNTs nanocomposite materials were synthesized by hydrothermal route in Teflon-sealed autoclave at 180oC for 10h. The FE-SEM and X-Ray diffraction measurements were taken for morphology and structural analysis of TiO2 nanoparticles doped with Fe coating on CNTs. The effects of the iron and CNTs on the enhanced photocatalytic activity for methylene blue degradation under AM 1.5 illumination of 100 mW.cm−2 were investigated.

Fabrication of hierarchical BiOI/Bi2MoO6 heterojunction for degradation of bisphenol A and dye under visible light irradiation

A novel hierarchical BiOI/Bi2MoO6 composites are prepared by a facile precipitation–deposition method. The prepared photocatalyst was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectrometer (XPS). The resulting BiOI/Bi2MoO6 composites exhibit excellent photocatalytic activity and stability towards the degradation of methylene blue (MB) and bisphenol A (BPA) in aqueous solution under visible light irradiation. The optimal composite with 25% BiOI content shows the highest photocatalytic activity for MB degradation. The enhanced photocatalytic activity is mainly attributed to the formation of BiOI/Bi2MoO6 heterojunction that can facilitate the separation and transfer of the photo-generated charge carriers. The roles of active species in the photocatalytic process are discussed by using different types of active species scavengers. Meanwhile, combined with the photoluminescence (PL) and electrochemical impedance spectroscopy (EIS), the degradation mechanism of the photocatalysts is proposed. It is hoped that the work could provide valuable information on the design of specific structure materials with more excellent properties and set the foundation for the further industrial application.