Preparation of ZnS-Fluoropolymer nanocomposites and its photocatalytic degradation of methylene blue

The ZnS particles were immobilized on the surface of poly(vinylidene difluoride) (PVDF) mixing methacrylic acid (MAA)-trifluoroethyl acrylate (TFA) copolymer electrospun nanofibers. The PVDF and MAATFA copolymer nanofibers were prepared by electrospinning. Zinc ions were introduced onto the surface of nanofibers by coordinating with the carboxyls of MAA, and then sulfide ions were added to react with zinc ions to form ZnS particles under hydrothermal condition. The size and the amount of ZnS particles increased with the reaction time prolonging. The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results reveal that a chemical interaction exists between ZnS and fluoropolymer fibers. The degradation rate of methylene blue in ZnS-fluoropolymer nanocomposite system was considerably higher than in that of ZnS powders system under UV irradiation. There may be an adsorption-migration-photodegradation process during the degradation of methylene blue by using ZnS-fluoropolymer nanocomposites as photocatalyst. The photocatalytic activity of ZnS-fluoropolymer nanocomposites changes indistinctively after 10 times repeating tests.     

纳米氧化锌光催化降解有机染料性能的研究

用自制的纳米ZnO在室外阴天、太阳光照射、室内紫外灯照射等条件下对不同有机染料的降解性能作了系统的研究。结果表明纳米ZnO在太阳光照射条件下对弱碱性有机染料溶液的降解效果较好。本文还比较了自制纳米ZnO与纳米TiO2对有机染料的降解性能，结果表明ZnO的降解效果优于TiO2。     

Biosynthesis of zinc oxide nanoparticles using Euphorbia milii leaf constituents: Characterization and improved photocatalytic degradation of methylene blue dye under natural sunlight

A facile biosynthesis route was followed to prepare zinc oxide nanoparticles (ZnO NPs) using Euphorbia milii (E. milii) leaf constituents. The SEM images exhibited presence of spherical ZnO NPs and the corresponding TEM images disclosed monodisperse nature of the ZnO NPs with diameter ranges between 12 and 20 nm. The Brunauer–Emmett–Teller (BET) analysis revealed that the ZnO NPs have specific surface area of 20.46 m²/g with pore diameter of 2 nm–10 nm and pore volume of 0.908 cm³/g. The EDAX spectrum exemplified the existence of Zn and O elements and non-appearance of impurities that confirmed pristine nature of the ZnO NPs. The XRD pattern indicated crystalline peaks corresponding to hexagonal wurtzite structured ZnO with an average crystallite size of 16.11 nm. The FTIR spectrum displayed strong absorption bands at 512 and 534 cm^?1 related to ZnO. The photocatalytic action of ZnO NPs exhibited noteworthy degradation of methylene blue dye under natural sunlight illumination. The maximum degradation efficiency achieved was 98.17% at an illumination period of 50 min. The reusability study proved considerable photostability of the ZnO NPs during photocatalytic experiments. These findings suggest that the E. milii leaf constituents can be utilized as suitable biological source to synthesis ZnO NPs for photocatalytic applications.     

Facile synthesis and characterization of Fe2O3 nanoparticles using L-lysine and L-serine for efficient photocatalytic degradation of methylene blue dye

In this work, Fe₂O₃ nanoparticles, abbreviated as OL and OS, were facilely synthesized by the combustion procedure using L-lysine and L-serine as organic fuels, respectively. Also, the OL and OS samples were identified using different instruments such as Raman spectrometer, FT-IR spectrophotometer, UV–Vis spectrophotometer, XRD, HR-TEM, BET surface area, and FE-SEM. The XRD confirmed that the mean grain size of OL and OS samples is 42.23 and 33.16 nm, respectively. The HR-TEM images confirmed that irregular, hexagonal, and spherical shapes, have an average diameter of 39.13 and 34.28 nm, were observed in the OL and OS samples, respectively. The BET surface area of the OL and OS samples is 16.20 and 28.34 m²/g, respectively. Additionally, the OL and OS samples were accomplished for the photocatalytic degradation of methylene blue dye in the absence and presence of hydrogen peroxide. The % degradation of 45 mL of 25 mg/L of methylene blue dye in the case of using OL and OS samples in the absence of hydrogen peroxide is 55.23 and 63.64 % after 120 min, respectively. Also, in the presence of hydrogen peroxide, the % degradation in the case of using OL and OS samples is 100 % after 35 and 25 min, respectively.     

Comparative study for the removal of methylene blue via adsorption and photocatalytic degradation

Physically and chemically activated carbons were prepared from date pits and olive stones. Titania and WO(x)-TiO(2)/MCM-41 were prepared as photoactive catalysts. Surface characterizations were investigated from ash content, pH, base neutralization capacities and FT-IR techniques. The textural characteristics, namely specific surface area (S(BET)) and pore texture, were determined from low temperature adsorption of N(2) at 77 K. The decolorization of aqueous solution of methylene blue was performed by means of two alternative methods. Steam-activated carbons own higher surface area compared with ZnCl(2)-activated carbons, and the micropore surface area represents the major contribution of the total area. Steam-activated carbons were the most efficient decolorizing adsorbents owing to its higher surface area, total pore volume and the basic nature of the surface. The calculated values of DeltaG(0), DeltaH(0) and DeltaS(0) indicate the spontaneous behavior of adsorption. The photocatalytic degradation is more convenient method in decolorizing of methylene blue compared with the adsorption process onto activated carbons.     

A novel study on synthesis of egg shell based activated carbon for degradation of methylene blue via photocatalysis

Egg shell-based activated carbon was successfully synthesized by the simple chemical activation process. Orthophosphoric acid and sodium hydroxide used as an activation agent. XRD pattern reveals the hexagonal structure of activated carbon. The functional group presents in activated carbon was identified using FT-IR spectroscopy. SEM images show irregular shapes of carbon. The photocatalytic performance of investigated activated carbon by illuminating methylene blue dye under UV–Visible irradiations. Photocatalytic activity of activated carbon results maximum degradation efficiency of 83%. Adsorption efficiency have been increased with respect of time for degradation of dye. Free radicals and superoxide’s play a significant role is decolourization of methylene blue. Photocatalytic activity of activated carbon synthesized by Orthophosphoric acid results shows the high degradation efficiency when compared to NaOH.     

Structural,optical and photocatalytic activity of cerium doped zinc aluminate

Zinc aluminate and cerium-doped zinc aluminate nanoparticles are synthesised by co-precipitation method. Ammonium hydroxide is used as a precipitating agent. The synthesised compounds are characterised by powder X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FT-IR), Ultraviolet diffuse reflectance spectroscopy (UV-DRS), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Surface area measurements. The photocatalytic activity of zinc aluminate and cerium doped zinc aluminate nanoparticles are studied under the UV light and visible light taking methylene blue as a model pollutant. The amount of catalyst, concentration of dye solution and time are optimised under UV-light. Degradation of methylene blue under the UV-light is found to be 99% in 20 min with 10 mg of cerium doped catalyst. Compared to visible light degradation, the degradation of dye under UV-light is higher. Cerium doping in zinc aluminate (ZnAl₂O₄:Ce³⁺) increased the photocatalytic activity of zinc aluminate.     

A new technique for the synthesis of lanthanum substituted nickel cobaltite nanocomposites for the photo catalytic degradation of organic dyes in wastewater

Developing cost-effective and more efficient nanocatalysts for the treatment of organic pollutants from process industry is always challenging for the researchers working in the field of chemistry, chemical, energy and environment engineering. In this work, a cost-effective and more efficient nanocatalysts, i.e., Nickel Cobaltite nanocomposites and its Lanthanum (La) doped derivatives with controlled surface morphology has been synthesized at 393.15 K through single step sol–gel method. The surface morphology, chemical composition, and crystal structure of the synthesized nanocomposites were analysed by scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR), and X-rays diffraction (XRD), respectively. The rough surface and well-crystallized metallic nanocomposites confirm the successful synthesis of nanocatalysts. The molar ratio of Lanthanum to Cobalt (La_x:Co_y) showed a significant influence on the surface morphology and catalytic activity (K_app = 0.15–0.47 min⁻¹) of the products. Synthesized nanocomposites showed high catalytic activity for the reduction of methylene blue under solar irradiation. Photocatalytic results for the reduction of methylene blue show that the catalytic activity of synthesized nanocatalysts increases with the increase in the doping concentration of Lanthanum.     

Enhanced photocatalytic activity of ZnO nanoparticles by surface modification with KF using thermal shock method

ZnO nanoparticles were modified with KF using thermal shock method at various temperatures in order to improve the photocatalytic activity of ZnO under both UVA and visible light irradiation. The influences of KF-modification on the crystal structure, morphology, UV–visible absorption, specific surface area as well as surface structure of ZnO were respectively characterized by XRD, FE-SEM, UV–Visible diffuse reflectance, N₂ adsorption and XPS spectroscopy. The photocatalytic activity was evaluated via the degradation of methylene blue under UVA irradiation. According to the results, the thermal shock process with KF did not modify the structure, the particle size and the optical properties of ZnO nanoparticles but successfully increase their UVA and visible light induced photocatalytic activity. This enhancement of activity may be attributed to the increase of surface hydroxyl groups and zinc vacancies of modified ZnO samples.     

Spherical NiWO4-reduced graphene oxide nanocomposite for effective visible light driven photocatalytic activity for the decolourisation of organic pollutants

A hybrid nanocomposite of nickel tungstate – reduced graphene oxide (NiWO₄-RGO) was prepared using a surfactant free hydrothermal approach. Resulting hybrid nanocomposite powder was grounded for forty minutes to ensure homogeneity and avoid agglomerations of particles. Resulting nanocomposite was characterised by XRD, FTIR, FESEM and EDX analysis. Photocatalytic activities of the characterised catalyst were examined by the decolourisation of Methylene blue (MB) and ortho-nitrophenol (ONP) under visible light irradiation were conducted at room temperature. The results confirmed that 15 wt% NiWO₄-RGO composite was degraded almost completely MB (95%) and ONP (82%) within 150 and 240 min respectively under visible light sources. The catalyst was reused and stable for successive six runs with loss of 10% of degradation rate.     

The influence of cobalt doping on photocatalytic nano-titania: Crystal chemistry and amorphicity

Photocatalysts of nominal composition (Ti_1−xCo_x)O_2−δ with 0.001?x?0.05 were prepared via a sol-gel technique followed by air firing (200-1000 °C). The incorporation of cobalt inhibited crystal growth and slightly raised the anatase to rutile transformation temperature (∼700 °C). An amorphous component was invariably significant with the maximum content (41-53 wt%) appearing simultaneously with the removal of anatase, suggesting that rutile crystallizes via an aperiodic structure. While the introduction of cobalt shifted the apparent band gap to visible light energies this did not enhance performance as there was limited miscibility of cobalt in titania, non-catalytic secondary phases were present, and active Ti³⁺ sites were displaced by cobalt.     

In-situ oxidative polymerization of aniline on hydrothermally synthesized MoSe2 for enhanced photocatalytic degradation of organic dyes

In this paper, we report synthesis of MoSe₂-polyaniline by in-situ polymerization method. Simple and eco-friendly hydrothermal technique is used for the synthesis of MoSe₂. Sample characterizations were done using Field Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), UV–vis Spectroscopy, Fourier Transform Infra-Red Spectroscopy (FTIR) and Raman Spectroscopy. Photocatalytic dye degradation was performed using nanocomposite on Methylene blue (MB) and Methyl orange (MO). Photocatalytic degradation efficiency (?) was found to be ～65% and ～94% for MB and MO, respectively. Reaction kinetics were studied and fitted well with pseudo first order model because of the mesoporous structure of polyaniline (PANI). Material reusability and regenerability was also checked for number of cycles.     

Microwave-assisted preparation and enhanced photocatalytic activity of Bi2WO6/BiOI heterojunction for organic pollutants degradation under visible-light irradiation

In this research, we adopted morphology control and constructing p-n heterojunction to boost the photocatalytic performance of BiOI. BiOI with three morphologies (nanoplate, micro-flower, microsphere) was fabricated via a wet-chemical method at room temperature using different solvents. And Bi₂WO₆/BiOI microspheres were successfully prepared by a microwave-assisted synthetic method. The as-synthesized samples were characterized by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive Spectroscopy (EDS) and High-resolution Transmission Electron Microscopy (HRTEM). The results of photo-degradation experiment demonstrated that BiOI-3 and BWOI-3 show high photocatalytic performance towards methyl orange (MO) and bisphenol A (BPA) degradation due to the high specific surface area, synergistic effect between p-type BiOI and n-type Bi₂WO₆ and high separation efficiency of electron-hole pairs, which is verified by Brunauer-Emmett-Teller (BET), Photocurrent (PC) and Electrochemical Impedance Spectroscopy (EIS) analysis. Moreover, the repeated photocatalytic experiment was carried out by using MO as the representative organic pollutant, manifesting the good durability of the sample.     

梯型BiVO4/Ag3VO4光催化剂的构建及其可见光光催化性能

近年来,有机污染物的问题变得越来越严重.为了解决该问题,人们研究和开发了许多有效的光催化剂.本工作采用水热法和化学沉积法合成了BiVO4/Ag3VO4梯型半导体材料,该复合材料在可见光下具有很强的氧化还原能力.其中40%BiVO4/Ag3VO4具有最佳的光催化降解性能,其降解速率为0.05588 min^-1,分别是BiVO4和Ag3VO4的22.76和1.76倍.并且其性能稳定,经过四次循环后其降解率仍可保持90%以上.BiVO4和Ag3VO4复合后,其催化性能得到增强,归因于形成了新型的梯型光催化机制,该方法促进了光生电荷的分离并延长了电荷的寿命,且通过PL测试和瞬态光电流响应证明了电荷的有效转移.X射线衍射(XRD)可以观察到Ag3VO4和BiVO4物相,没有其他成分.用扫描电子显微镜(SEM)和透射电子显微镜(TEM)进一步观察了该催化剂的结构和形貌,从SEM可以看出,Ag3VO4生长在BiVO4的上面,能谱分析也证明该催化剂仅包含Ag3VO4和BiVO4的各种元素,而不含其他杂质,TEM进一步证明了两种物质复合在一起,而不是机械混合.通过紫外-可见光漫反射光谱(UV-vis)测试可以得到BiVO4和Ag3VO4的吸收带边,进一步计算BiVO4的带隙和导带分别为2.41和0.455 eV,Ag3VO4的带隙和导带分别为2.20和0.04 eV,二者组成的异质结的带隙满足降解的条件.用荧光光谱(PL)和光电流研究了样品的光电特征,结果表明BiVO4/Ag3VO4光催化剂具有很高的载流子分离效率和很低的光电流电阻,这有助于光生载流子的运输.光催化降解甲基蓝实验表明,BiVO4/Ag3VO4具有很强的光催化降解速率(0.05588 min^-1),是BiVO4的22.6倍,Ag3VO4的1.76倍,而且经过四次循环后仍能保持很高的活性.通过XRD发现使用后的催化剂并没有发生变化,说明该催化剂具有良好的稳定性.高分辨X射线光电子能谱(XPS)不仅进一步说明了该催化剂成功复合后没有其他杂质元素,而且从各元素的结合能变化可以看出构成异质结后电子的流向,证实了光催化机制为梯型机制.光照射后,BiVO4和Ag3VO4产生电子空穴对,当催化剂受光激发后,电子从价带被激发到导带,并在价带留下空穴.当BiVO4和Ag3VO4复合后,在接触界面形成内电场,由于库仑相互作用,能带边缘弯曲等作用加速了Ag3VO4价带上某些空穴和BiVO4导带上电子的复合,从而阻止了Ag3VO4和BiVO4内部电子空穴对的复合,这有助于Ag3VO4导带上的电子和BiVO4价带上的空穴参与氧化还原反应.从捕获实验可以看出,本实验中空穴在光催化降解中起着最重要的作用,这与上述结论一致.     

Selective fabrication of porous iron oxides hollow spheres and nanofibers by electrospinning for photocatalytic water purification

Porous hematite (α-Fe₂O₃) hollow spheres and nanofibers could be obtained via electrospinning and subsequent thermal decomposition in air. The precursor could be fabricated by electrospinning using Fe(NO₃)₃ as the iron source and Polyvinylpyrrolidone (PVP) as a complexing reagent. Upon calcination, pure porous α-Fe₂O₃ hollow spheres and nanofibers could be obtained at 650 °C for 3 h. The novel hollow spheres have an abundantly porous structure as well as large surface areas. Benefitting from the special porous structure, narrow bandgap, and higher surface area, porous α-Fe₂O₃ hollow materials are used as visible-light-responsive photocatalysts. So we have investigated the visible light photodegradation behavior of porous hematite (α-Fe₂O₃) hollow spheres and nanofibers towards organic dyes, as Rhodamine B (RhB). The synergetic effects of higher surface area, pore structures promoted the photocatalytic efficiency for RhB degradation under visible light and contributed to achieving the enhanced and stable photocatalytic activity.     

Visible-light photocatalytic activation of N-chlorosuccinimide by organic dyes for the chlorination of arenes and heteroarenes

A variety of arenes and heteroarenes are chlorinated in moderate to excellent yields using N-chlorosuccinimide (NCS) under visible-light activated conditions. A screening of known organic dye photocatalysts resulted in the identification of methylene green as the most efficient catalyst to use with NCS. According to mechanistic studies described within, the reaction is speculated to proceed via a single electron oxidation of NCS utilizing methylene green under visible-light photoredox pathway. The photo-oxidation of NCS amplifies the electrophilicity of the chlorine atom of the NCS, thus leading to enhanced reactivity as a chlorinating reagent with aromatic substrates.     

Effective photocatalytic degradation of organic pollutant by ZnS nanocrystals synthesized via thermal decomposition of single-source precursor

2-Aminocyclopentene-1-dithiocarboxylate complex of zinc(II) has been synthesized and found to be an effective single-source precursor for the preparation of ZnS NCs (rod and sphere) by the use of ethylenediamine and hexadecylamine as structure directing solvents. Structural characterizations were carried out using XRD, TEM and BET measurements and the optical properties by UV-Vis and PL spectroscopic techniques. The prepared ZnS NCs show effective photocatalytic activity towards the degradation of Rose Bengal dye (RB) under light irradiation for their probable application in waste water treatment. The degradation mechanism of RB dye under light irradiation is established by terephthalic acid photoluminescence probing technique.     

Characterization of Titanium Dioxide Doped with Nitrogen and Sulfur and its Photocatalytic Appraisal for Degradation of Phenol and Methylene Blue

The degradation of organic dyes in the presence of modified TiO₂ is still under intensive investigation. We report here an evaluation of the photocatalytic activity of nitrogen‐ (N‐) and sulfur‐ (S‐) doped TiO₂ for the degradation of phenol and methylene blue (MB). N‐doped TiO₂ (N–TiO₂), S‐doped TiO₂ (S–TiO₂), and N–S‐doped TiO₂ (N–S–TiO₂) were prepared using the sol–gel method. The photocatalytic activity was evaluated in a batch reactor using phenol and MB as models of pollutants. In addition, this investigation was performed using a household lamp as the visible light source. Properties of the synthesized materials in terms of Brunauer–Emmett–Teller (BET) surface analysis, field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and photocatalytic ability were examined. Our study shows that N–S–TiO₂ exhibits better photocatalytic degradation ability for all the considered dyes compared to the other doped TiO₂ materials. In conclusion, we have successfully prepared and evaluated the photocatalytic activity of N‐ and S‐doped TiO₂ for the degradation of phenol and MB using an ordinary household lamp.     

Antibacterial,antioxidant and photocatalytic activity of novel Rubus ellipticus leaf mediated silver nanoparticles

Nanotechnology is an emerging field of science that has significant applications in applied sciences. In this study, silver nanoparticles (SNPs) were synthesized utilizing the leaf filtrate of Rubus ellipticus. SNPs were characterized using UV–visible spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction patterns to determine their morphology and chemical composition. The surface plasmon resonance of SNPs revealed a peak at 415 nm. The synthesized SNPs were mainly spherical crystals with an average size of 21.43 nm. When compared to plant extract and positive controls (AgNO₃ and penicillin), SNPs demonstrated significant bactericidal activity against all the tested bacteria (gram-positive and gram-negative). The most effective bactericidal activity was found against Pseudomonas aeruginosa, with a minimum inhibitory concentration of 1.25 µg/mL. In addition, a dose-dependent antioxidant activity of SNPs was found against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical with an average IC50 value of 72.84 µg/mL. The photocatalytic activity of Methylene blue (MB) dye decomposition under sunlight was studied. The results showed that MB degraded by 98 % after 150 min in the sun. Overall, the findings of this study indicate that R. ellipticus biosynthesized SNPs may have bactericidal and photocatalytic effects.     

Preparation of Ce‐doped TiO2 Hollow Fibers and Their Photocatalytic Degradation Properties for Dye Compound

Cerium‐doped titanium dioxide (TiO₂) with a hollow fiber structure was successfully prepared using ammonium ceric nitrate and tetrabutyltitanate as precursors and cotton fiber as the template. The effects of cerium (Ce)‐doping on the crystallite sizes, crystal pattern, and optical property of the prepared catalysts were investigated by means of techniques such as scanning electron microscopy (SEM), X‐ray diffraction (XRD), BET surface area, and UV‐vis diffuse absorption spectroscopy. SEM observation showed that the prepared TiO₂ fibers possessed fibrous shape inherited from the cotton fiber and had a hollow structure. As confirmed by XRD and UV‐vis diffuse absorption spectroscopy examinations, Ce‐doping restrained the growth of grain size and extended the photoabsorption edge of TiO₂ hollow fiber into the visible light region. The present photocatalyst showed higher photocatalytic reactivity in photodegradation of highly concentrated methylene blue (MB) solutions than pure TiO₂ under UV and visible light, and the amount of Ce‐doped significantly affected the catalytic property. In the experiment condition, the photocatalytic activity of 0.5 mol% Ce‐doped TiO₂ fiber was optimal of all the prepared samples. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed. The material was easily removed by centrifugal separation. Therefore, using the template method and by doping with cerium, TiO₂ may hopefully become a low‐energy consuming, high activity and green environmentally friendly catalytic material.