Photodegradation Of Methylene Blue Dye Research Articles

Enhanced photocatalytic activity of $$\hbox {SnO}_{2}$$ NPs by chromium (Cr) concentration

This study reports the synthesis of un- and chromium (Cr)-doped tin dioxide \((\hbox {SnO}_{2})\) nanoparticles (NPs) through chemical precipitation and their application for photodegradation of methylene blue dye. The obtained NPs were characterized by X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, elemental mapping and ultraviolet–visible (UV–Vis) spectroscopy. The TEM and XRD results demonstrated that the \(\hbox {SnO}_{2}\) NPs are spherical and contain polycrystalline tetragonal crystals. UV–Vis spectra showed that increasing the concentration of the Cr dopant enhances the light absorption potential of the \( \hbox {SnO}_{2} \) NPs. Finally, the findings of the photocatalytic experiments performed for 120 min in ultraviolet irradiation under ambient conditions revealed an improvement in the degradation efficiency of the \( \hbox {SnO}_{2} \) NPs by Cr doping.

Easy Synthesis Method of MoS2/TiO2 Nanostructure with Great Performance of Catalytic Activity Under Visible Light

In this study, TiO2 nanoparticles modified with MoS2 were synthesized using the low temperature hydrolysis method. Samples of pure TiO2 and samples of MoS2 /TiO2 were prepared using different amounts of MoS2 (1.0% and 10.0% by weight). The samples were annealed at 500°C and 700°C and characterised by ICP-AES, XRD, Raman, FT-IR, TG, XPS and DR-UV-Vis spectroscopy. The results suggest that the MoS2 added during synthesis is a satisfactory source of Mo to produce doping of the TiO2 structure. In addition, the transformation of anatase phase to rutile is delayed when the concentration of Mo incorporated into the structure increases. Finally, the effectiveness of the synthesized MoS2 /TiO2 samplesused as photocatalyst for the photodegradation of methylene blue dye under visible light irradiation was investigated. TiO2 doped with MoS2 was shown to improve the degradation of methylene blue under visible light. There was found to be an optimal temperature and level of doping to achieve improved photocatalytic activity, in our case 10.0% MoS2 /TiO2 at 700°C.

Effect of Zr doping and aging on optical and photocatalytic properties of ZnS nanopowder

Abstract A facile single step chemical method is reported for the synthesis of Zr doped ZnS nanopowder and its photocatalytic performance has been studied. The average crystallite size of the synthesized powder estimated from X-ray diffraction (XRD) is nearly 1.1 nm. Transmission electron microscopy (TEM) study shows that nanoparticles are agglomerated having a particle size of nearly 10 nm. The optical band gap of ZnS and Zr-doped ZnS, estimated with the help of UV–visible spectroscopy, is 3.7 and 2.9 eV, respectively. Photoluminescence (PL) spectroscopy indicated the role of lattice defects (vacancy, interstitial defects) on optical emission characteristics of doped ZnS samples. The photocatalytic activity of synthesized samples has also been investigated by degrading methylene blue (MB) dye under UV–visible illumination. The degradation quenching has been observed beyond 0.4 mol% doping of Zr in ZnS with maximum efficiency i.e. 80% in 4 h. Thereafter, the effect of aging is monitored for 1.5 months in which the modified emission properties of defect sites modulated the photocatalytic performance of Zr-doped ZnS sample. Further, with the help of various spectroscopic techniques (absorbance, PL and XPS), a mechanism for the photodegradation of MB dye by using Zr-doped ZnS nanopowder has been proposed.

Synthesis and Characterization of Nanocomposite Acrylamide TIN(IV) Silicomolybdate: Photocatalytic Activity and Chromatographic Column Separations

A nanocomposite acrylamide tin(IV) silicomolybdate (AC/TSMNC) was chemically synthesized by the sol–gel technique in surfactant medium at room temperature. The synthesis conditions, such as reactant concentrations, pH and temperature were varied to optimize the ion exchange properties of the nanocomposite ion exchange material. The ion exchange capacity was found to be 1.92 meq/g for Na+. The nanocomposite was characterized on the basis of chemical composition, Fourier-transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies. The interpretation of the XRD pattern indicated its semi-crystalline nature. The diamond shape morphology was observed in SEM studies. The particle size of the material was in the range of 50‒100 nm as indicated by TEM. Sorption studies were performed in a number of solvent systems showing high selectivity for Pb(II) and Ni(II) in synthetic mixtures. On the basis of distribution coefficient studies several binary separations of metal ions, viz. Mg2+–Pb2+, Mg2+–Ni2+, Sr2+–Pb2+, Sr2+–Ni2+, Zn2+–Pb2+, Zn2+–Ni2+ were achieved quantitatively on acrylamide tin(IV) silicomolybdate columns. The quantitative separation of Ni2+ and Zn2+ was also achieved on a commercially available pharmaceutical formulation (Rxplus). Photocatalytic degradation of methylene blue dye onto AC/TSMNC was investigated for 3.5 h under solar light at a wavelength of 664 nm. The rate of methylene blue dye photodegradation onto AC/TSMNC was found to follow the pseudo-first-order kinetic model.

Structural, optical properties of ZnO doped SnO2 nanocomposites with enhanced photocatalytic performance under UV illumination

ZnO doped SnO2 nanocrystallites are fabricated by the sol-gel technique in the existence of polyethylene glycol as a template and characterized by various techniques for structural, morphological and optical properties. The photocatalytic efficiency of the synthesized photocatalysts is assessed by photodegradation of methylene blue dye under ultraviolet light illumination. The ZnO/SnO2 molar ratios are changed in order to study their effect on the photocatalytic efficiency. The ZnO/SnO2 nanocrystallites are a most efficient photocatalyst with the efficiency of 1.0:1.0 in molar ratio and it is attributed to the existence of heterojunctions between the ZnO and SnO2. This allows increased charge parting of the photogenerated electron/hole pairs due to the energy difference amongst the two oxides.

Intrinsic self-healing and biocompatibility of carbon nitride coatings via inhibiting or degrading ethylene for fruit preservation

Intrinsic self-healing of C3N4 coatings based on host–guest interaction was achieved on fruit substrates via layer-by-layer assembly technique. The coatings were made of alternating layers of poly(ethylenimine)-β-cyclodextrin (PEI-βCD), poly(acrylic acid)-adamantanamine (PAA-AD), and carbon nitride (C3N4). The ultrasonic treatment was used to inhibit C3N4 agglomeration and to form a homogeneous suspension of PEI-βCD-C3N4. Then, PAA-AD and PEI-βCD-C3N4 were self-assembled to obtain the (PAA-AD/PEI-βCD-C3N4)*15 coatings. The photoactivity of the coatings was monitored using photodegradation of methylene blue dye under visible light. We hypothesized that the coatings could be applied to banana fresh-keeping packaging materials by inhibiting or degrading ethylene. The results verified that the coatings possessed excellent degradablility and fresh-keeping performances. Moreover, cell viability tests showed that the coatings exhibited good biocompatibility. In particular, the coatings exhibited excellent self-healing property due to the reversible nature of the host–guest interaction. The coatings show great potential for applications in multifunctional commercial supplies, such as packaging materials.

Facile and low-cost fabrication of ZnO/biochar nanocomposites from jute fibers for efficient and stable photodegradation of methylene blue dye

The present work demonstrates the fabrication of ZnO loaded on biomass porous carbon through pyrolysis of jute fibers pretreated by Zn(OAc)2. XRD, Raman SEM, TEM, XPS and physical adsorption of nitrogen were used to characterize the products. Dark adsorption and photocatalytic degradation of methylene blue (MB) was run to evaluate their activities for removal of organic pollutants. It was demonstrated that the composition and structure of ZnO/JFC composites depended on the ratios of jute fibers to zinc salt. Through adjusting the mass ratio between raw materials, a fine composite of ZnO monocrystalline nanorods embedded on the porous carbon walls was obtained, which exhibited a much better efficiency for MB decolorization. The removal of MB was found to be pH dependent, and the optimized removal efficiency reached to 99% and the mineralization level was over 93% at pH 7.0 following 30 min under UV illumination. The kinetic studies showed the decolorization of MB followed pseudo first-order kinetics, and the rate constants were determined using the Langmuir–Hinshelwood model, indicating KLH = 0.024 L∙mg−1and kc = 4.01 mg∙L−1 min−1. Moreover, the ZnO nanorods/JFC composite was stable and showed a high efficiency of over 80% during seven cycles of utilization and regeneration. Examination for the real sample contaminated by MB proved that the presence of metal ions and other organic pollutants hardly affected its photocatalytic ability. It was demonstrated that ZnO/JFC composites could be fabricated through simultaneous pyrolysis of jute fibers and zinc acetate. These composites were provided with the advantages of high photocatalytic efficiency, convenient recycling and long-term stability, and were expected to be applied in environmental engineering and manufacturing for organic dyes removal.

NbC/C heterojunction for efficient photodegradation of methylene blue under visible irradiation

Photocatalysis has emerged as a vital tool for purification of waste water and also to obtain alternate fuels (H2) through water splitting. TiO2, ZnO and other non-carbide systems (ZnS, metallic nanoparticles (NPs), etc.) have been studied thoroughly to enhance their photocatalytic performances through doping and the formation of heterojunctions. But, niobium carbide (NbC) is gaining interest of researchers due to its ability to catalyze electrochemical reactions (hydrogen evolution reaction and oxygen reduction reaction) along with excellent thermal and chemical stability. In the present work, NbC has been synthesized using conventional oxide precursor (Nb2O5), Mg metal powder and parthenium hysterophorous (PH; carrot grass, an agricultural hazardous weed) as carbon source at relatively low temperature (800 °C) as compared to conventional synthesis temperature (1200 °C). For the phase confirmation and morphological studies, X-ray diffraction and transmission electron microscopy have been done. It has been observed that the presence of NbCxOy/NbOz inside NbC nanoparticles induced the optical active sites resulting photocatalytic degradation of methylene blue (MB) dye under visible irradiation. With the help of various techniques (UV–visible, PL, XPS, RAMAN spectroscopies and scavenger tests), degradation mechanism has been established for the observed photocatalytic performance of synthesized NbCxOy/NbOz/NbCx/g-C heterostructure under optimized conditions. Further, for the confirmation of photodegradation of MB dye, mass spectrometry and TOC have also been carried out.

Synthesis, Characterization, Photocatalytic Activities and Reusability of Eu-ZnO-Ag Nanoparticles using Sunlight/LEDs Illuminations

Photocatalyst (Eu–ZnO–Ag) was synthesized by precipitation-decomposition process. The characterization catalyst by phase and size of catalyst by powder-XRD, morphology of catalyst by FE-SEM and optical properties by UV-visible and emission spectroscopy. The photocatalytic action of Eu–ZnO–Ag was investigated in the photodegradation of methylene blue dye in water under LEDs/ solar light. Eu–ZnO–Ag catalyst is indicating the excellent activity than Ag–ZnO, Eu–ZnO commercial ZnO/TiO2 nanoparticles. Co-dopants (Eu/Ag) shift the light absorbance of ZnO toward visible region. Factor affecting of photodegrdation study by dose, dye, solution pH on of methylene blue dye present solar/LEDs. The Eu–ZnO–Ag is established to be reusable photocatalyst. A potential photodegradation of methylene blue mechanism was discussed under illuminations LEDs/solar light.

Synthesis of Metal/Silica/Titania Composites for the Photocatalytic Removal of Methylene Blue Dye

The present work deals with the synthesis of the metal-doped titanium dioxide/silica composite by using the sol-gel method. The structure, morphology, and composition of the prepared samples were characterized by using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The prepared composites were used for the photodegradation of methylene blue dye in sunlight. Different parameters like pH, time, and catalytic concentration were varied to optimize the reaction conditions. Maximum 99.8% degradation was observed with the Ni-doped composite. The results indicate extraordinary efficiency of all metal-doped composites for the removal of the harmful organic pollutant like methylene blue.

Self-Assembly of Nanostructured Hydroxyapatite Spheres for Photodegradation of Methylene Blue Dye

Abstract Calcium phosphate compounds in the form of apatites represent the basic building blocks of bones and teeth. Among them, Hydroxyapatite has drawn great attention towards biomedical and environmental applications owing to their exceptional biocompatibility, osteoconductivity and adsorption/desorption properties. However, development of self-assembled hydroxyapatite nanostructures is a challenging issue amidst the materialists. Hence, an attempt has been made to synthesis nanostructured hydroxyapatite spheres by a facile hydro/solvothermal method to explore its photocatalytic activity. The crystallinity and purity of the nanostructures were confirmed by X-Ray Diffraction and Fourier Transform Infrared Spectroscopy respectively. The Field Emission Scanning Electron Microscopic images depicted the surface morphology and the detailed growth mechanism was discussed. Furthermore, the as-prepared hydroxyapatite spheres were analyzed for the degradation of methylene blue dye under UV irradiation.

Influence of doping with Sm3+ on photocatalytic reuse of ZnO thin films obtained by spin coating

ABSTRACT The difficulty in the powder reuse favors the study of materials in the form of thin films. ZnO based films have high photocatalytic potential. In this work, ZnO:xSm3+ (x = 0, 1, 2 and 4 %mol) thin films were prepared by spin coating method. The resins obtained to manufacture the thin films were prepared by complex polymerization method. The samples were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM) and spectroscopy UV-Vis. XRD patterns indicate that doping with 4%Sm forms Sm2O3 as the secondary phase. FE-SEM images of the cross section of thin films indicated a uniform thickness ranging from 354 to 367 nm between samples. The incorporation of Sm3+ ions in the ZnO lattice increases the Egap of the films. The photocatalytic performance of the films was tested with the photodegradation of methylene blue dye. Pure ZnO and ZnO:1%Sm3+ exhibited the best activity in the photodegradation. Thin films of pure ZnO exhibit the best photocatalytic results for the first cycle, but considerably reduce their efficiency with reuse. Sm3+ incorporation, without secondary phase formation, was efficient for the maintenance of the photocatalytic property after 3 cycles.

Construction of a novel ternary composite of Co-doped CdSe loaded on biomass carbon spheres as visible light photocatalysts for efficient photocatalytic applications.

The cobalt doped cadmium selenide/biomass carbon spheres (Co-CdSe/BCS) photocatalyst is easily prepared using a transitory hydrothermal reaction lasting 40 min. The Co-CdSe/BCS photocatalyst is constructed using the in situ growth of Co-CdSe nanodots on the surfaces of the BCS. Doped Co2+ generates an electron trap, which can capture the photoinduced electrons, resulting in the efficient separation of the photoinduced electron-hole pairs. Furthermore, the introduction of carbon spheres enhances the optical absorption property and the ability for electron transport. Results of electrochemical characterization and photoluminescence spectra demonstrate that the Co-CdSe/BCS is able to efficiently separate electron-hole pairs and inhibit their recombination. The as-synthesized samples display high efficiency for the photodegradation of methylene blue dye under visible light. This study offers a new strategy to promote photocatalytic performance of the CdSe photocatalyst.

Synthesis of Nitrogen-doped RGO/BaWO<sub>4</sub> Nanocomposites with Highly Enhanced Photocatalytic Activity

A serious of nitrogen-doped reduced graphene oxide/barium tungstate (NRGO/BaWO4) nanocomposites has been synthesized by microwave method and it was examined by the photocatalytic studies for the degradation of methylene blue (MB) dye under visible light irradiation. The as-synthesized catalysts were confirmed by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Photoluminescence Spectroscopy (PL) and Diffuse Reflectance Spectroscopy (DRS) techniques. The prepared nanocomposites are tested for its performance to the photodegradation of MB dye via illumination of 120 minutes under visible light source. Significantly, the 2.5%-NRGO-BaWO4 nanocomposite indicated that the highest photocatalytic activity under visible light source. The observed photocatalytic performances were ascribed to the synergetic effects of NRGO and BaWO4 and improved photogenerated electron-hole pairs charge separation efficiency. On the basis of the experimental results, we concluded that the new strategy of these types of photocatalytic property of NRGO/BaWO4 based binary nanocomposites materials can be a suitable candidate for the various environmental applications.

Effect of temperature on structural and optical properties of solvothermal assisted CdS nanowires with enhanced photocatalytic degradation under natural sunlight irradiation

Photocatalytic degradation of toxic dyes is an important topic across the globe. This paper reports the photocatalytic degradation of methylene blue (MB) dye using cadmium sulfide (CdS) nanowires as a photocatalyst under natural sunlight irradiation. The CdS nanowires were successfully synthesized by a solvothermal route using ethylenediamine as a solvent with a series of different reaction temperature from 160 to 200 °C for a fixed time of 24 h. Multiple characterization techniques were used to investigate the structural, morphology, optical and photocatalytic study of as-synthesized CdS samples. The XRD patterns reveal highly crystalline CdS nanomaterials with a hexagonal crystal structure. The FESEM and HRTEM observations clearly confirmed a large number of uniform nanowires grown in different directions and interconnected with each other. The stoichiometric ratio of Cd:S is almost 1:1, confirmed by EDS analysis. Room temperature PL spectra of CdS nanowires exhibit a narrow emission at a wavelength of 512 nm. The CdS nanowires synthesized at 200 °C shows the excellent photocatalytic performance with highest photodegradation efficiency has reached up to 98.75% within 20 min, under sunlight irradiation. The 93.06% and 89.10% photodegradation efficiency were observed in CdS nanowires synthesized at 180 °C and 160 °C, respectively. From these result, it is observed that the crystallite size and morphology of CdS nanowires are the influence factors for the photodegradation efficiency of MB dye. Furthermore, the mechanism of MB dye photodegradation using CdS nanowires was discussed. These CdS nanowires with high photocatalytic activity can be used for future in water pollutant degradation.

LDH-VB9-TiO2 and LDH-VB9-TiO2/crosslinked PVA nanocomposite prepared via facile and green technique and their photo-degradation application for methylene blue dye under ultraviolet illumination

Abstract Vitamin B9 (VB9) as a biological molecule was used for the intercalation of MgAl-layered double hydroxide (LDH) which can increase the active sites and organic nature of LDH samples. Then, the LDH-VB9-TiO2 composite was synthesized with mass ratio of LDH-VB9:TiO2 equal to 1:1 through ultrasonic technique as a green and environmentally approach, and then the LDH-VB9-TiO2 was applied with three different mass ratios as organic-inorganic fillers in order to prepare in-situ crosslinked poly(vinyl alcohol) (CSPVA) nanocomposites (NC)s. The physio-chemical structure of CSPVA NCs was studied with variety of analyses such as FT-IR, XRD, FE-SEM, TEM and TGA. Finally, the prepared compounds were used for the photo-degradation of methylene blue (MB) dye from aqueous solution under ultraviolet lights. The photo-degradation performance of samples showed that the rate constant of Kapp was in the order of LDH-VB9-TiO2 > TiO2 > LDH-VB9/TiO2-CSPVA NC. Moreover, the value of half-life for degradation of MB dye was very remarkable for LDH-VB9-TiO2 sample (t1/2 = 81.53 min) in compared to the MB degradation without any photocatalyst sample (t1/2 = 6930 min). So, it can be concluded that the LDH-VB9 with nano-sheet structure has significant effect on the photo-degradation of MB dye in the presence TiO2. These kinds of NCs can be used as economy and environmentally friendly compounds in the industrial applications such as water purification.

Efficient photodegradation of methylene blue (MB) under solar radiation by ZrC nanoparticles

Due to increase in water pollution, there is a need to dwindle this problem for a clean and green future. Photocatalysts like ZnO, CaO and TiO2 have proved to be triumphant in removal of environmental contaminants. In this present work, ZrC nanopowder has been synthesized using a single-step reduction technique by heating zirconium oxide (ZrO2) and hexane (C6H14) in metallic Mg powder and is used as a photocatalyst for the degradation of methylene blue (MB) dye under solar radiation. Optimization of synthesis parameters (temperature, holding time and carbon content) has been done to obtain single phase ZrC. Various characterization techniques like X-ray diffraction (XRD), transmission electron microscope (TEM), differential scanning calorimetry/thermal gravimetric analysis (DSC/TGA) and X-ray photoelectron spectroscopy (XPS) were studied for various structural, thermal and surface characteristics of as-synthesized samples. The effect of synthesis parameters on crystal distortion of ZrC particles was studied with the help of Double Voigt analysis. Further, the comparative catalytic activity as photodegradation of MB dye with the help of optimized sample was studied under UV and solar radiations. As an effect of illumination source with the same concentration of catalyst and dye, 80% degradation was observed under solar radiations which is quite higher than that observed under UV in 5 h.

Photocatalytic, biodiesel, electrochemical sensing properties and formylation reactions of ZnO nanoparticles synthesized via eco-friendly green synthesis method

ZnO nanoparticles (NPs) were synthesised through green synthesis method with different concentrations of non-germinated razma (NG) seeds and germinated razma (G) seeds powder as a fuel through. The obtained ZnO NPs were characterised by XRD, FTIR, SEM, TEM analytical techniques. The non-germinated and razma germinated seeds powder ratios are the effect on the structure, morphology, UV concentration, PL emission and photodegradation of dye were analysed. The different structure and shape of NPs were explored for the photodegradation of methylene blue dye. The improved photodegradation of zinc oxide NPs was characteristics of slight crystal dimension, new superficial deficiencies, more band hole and ability to make smaller the electron–hole pair rearrangement. The electrochemical property of the synthesized ZnO NPs has been shown by quantifying dopamine at micro molar concentration levels. In the present study, preparation of biodiesel using ZnO nanocatalyst, Pongamiapinnata oil was used. The chemical process of amines with formic acid in the presence of a ZnO nanocatalyst under solvent-free conditions gives a high yielded protocol for the N-formylation to form the corresponding formamide derivatives.

Ag activated SnO2 films for enhanced photocatalytic dye degradation against toxic organic dyes

In the present work, tin oxide and Ag doped tin oxide thin films were fabricated using jet nebulizer spray pyrolysis technique and the photocatalytic properties of the prepared samples were analyzed by studying the photodegradation of methylene blue dye under visible light. The rate constant value is 0.0254 and 0.0193 min−1 for SnO2 and SnO2:Ag films, respectively. The results confirm that SnO2:Ag film exhibits better photocatalytic activity compared to SnO2 film. The XRD study shows that the film has tetragonal rutile structure of SnO2. The mechanism involved in the enhancement of the photocatalytic efficacy of the SnO2 film due to the addition of Ag is explained on the basis of photoluminescence, FESEM, AFM and optical studies.

Effects of oxygen vacancy and sintering temperature on the photoluminescence properties and photocatalytic activity of CeO2 nanoparticles with high uniformity

Gamma-ray irradiation assisted polyacrylamide gel route was applied to synthesize the homogeneous CeO2 nanoparticles. XRD results and optical properties indicates that the vacancy concentration and the energy gap (Eg) value of CeO2 nanoparticles increases with the increasing crystallite size. Photoluminescence experiment indicates that a small number of –CH and –CH2, and C–O functional groups in presence of the CeO2 nanoparticles can help improve the photoluminescence properties of CeO2 nanoparticles. Photocatalytic experiment results indicate that the pure CeO2 nanoparticles exhibits an obviously enhanced photocatalytic activity due to its have higher vacancy concentration. The dye concentration of 5 mg L−1 and the catalyst concentration of 1 g L−1 were fixed for photocatalytic degradation of methylene blue (MB) dye. In addition, the CeO2 nanoparticles containing –CH and –CH2, and C–O functional groups exhibits an outstanding adsorption capacity, however, it is not advantageous to the photo-degradation of MB dye. Based on the experimental results, a possible photocatalytic mechanism for organic decorated the CeO2 nanoparticles are discussed.