Dye Degradation

The azo class of synthetic dyes represents one of the most industrially used dyes as well as a major class of environmental contaminants, which possess one or more azo bonds (ÀN¼NÀ) along with aromatic rings and sulfonic groups. Due to its recalcitrant nature and toxicity for animals and human beings, the elimination of these dyes from the environment is essential. The present study focuses on the biodegradation of such azo dye, malachite green (MG), through a potent ligninolytic fungus, Aspergillus flavus (F10). A. flavus (F10) completely decolorized MG (150 mg L À1) within 6-8 days in optimized Kirk's basal medium under static aerobic conditions at pH 5.8. Sucrose and sodium nitrate were efficient carbon and nitrogen sources, respectively. The products obtained after degradation were examined using UV-vis spectrophotometry, Fourier transform IR spectroscopy, and liquid chromatography-mass spectroscopy. The metabolic intermediate products were identified as N-demethylated and N-oxidized metabolites, including primary and secondary arylamines, which confirms the involvement of laccase and manganese peroxidase in decolorization and degradation of MG. The end products of MG degradation were nontoxic. A. flavus (F10), immobilized by entrapment on natural and synthetic polymeric matrices was found to be a more efficient degrader of MG as compared to free cells.

Annually, large volumes of synthetic textile dyes are released in effluent into natural streams causing damage to human health and environment. Conventional methods have been proven inefficient due to the stability of these dyes. An alternative emerging approach is the use of nanocatalysts in photocatalytic dye degradation. In this study, the ability of citrate-stabilized silver nanoparticles (cit-AgNP) to degrade methylene blue (MB) dye was investigated. Cit-AgNP was successfully synthesized using chemical reduction method and stabilized by sodium citrate. The resulting solution was yellow in color with absorbance peak at 393 nm. The particles were spherical in shape with average diameter of 9.19 ± 4.91 nm. In the degradation study, the photocatalytic degradation of MB is visually manifested by its reduction in color when exposed to light and the eventual reduction in absorbance at peak 663 nm. The percent degradation was quantified by calculating the amount of MB that remained in the solution and showed 94.45% after 10 minutes of exposure to light. Four different setups were also compared and analyzed based on color changes, absorbance curve profiles, and percent degradation to prove the catalytic activity of cit-AgNP and it was found out that the highest and fastest degradation was the setup with MB, NaBH4, and cit-AgNP. River water samples were also utilized to evaluate the effectivity of degradation in real water applications. It has showed no significant difference compared to the setup prepared with distilled water after statistical tests. Hence, this study showed the potential of cit-AgNP for dye degradation.

The festival of 'Holi' is proving to be an environmental risk due to the toxic colors used during the celebrations. Unlimited and uncontrolled use of such dyes can lead to grave consequences in terms of human health and ecological balance. These colors are highly structured polymers and are very difficult to decompose biologically. This study was taken up with an initiative to determine the extent of effects that the 'Holi' colors have on water and soil, respectively. The bacteria inhabiting these contaminated water and soil samples were isolated for biochemical analyses. Their ability to degrade these dyes was determined after optimization studies. Toxic trials were conducted on certain bacterial cultures and Triticum vulgare to check their impact on the other living flora and fauna in their surrounding environment. After carefully monitoring the dye degradation capacity of these bacteria, they were used for bioremediation purposes, giving promising results. The impact assessment and damage control led to safer methods of getting rid of the 'Holi' dyes, in order to save our environment.

In materials science, "green" synthesis has gained extensive attention as a reliable, sustainable, and eco-friendly protocol for synthesizing a wide range of materials/nanomaterials including metal/metal oxides nanomaterials, hybrid materials, and bioinspired materials. As such, green synthesis is regarded as an important tool to reduce the destructive effects associated with the traditional methods of synthesis for nanoparticles commonly utilized in laboratory and industry. In this review, we summarized the fundamental processes and mechanisms of "green" synthesis approaches, especially for metal and metal oxide [e.g., gold (Au), silver (Ag), copper oxide (CuO), and zinc oxide (ZnO)] nanoparti-cles using natural extracts. Importantly, we explored the role of biological components, essential phytochemicals (e.g., flavonoids, alkaloids, terpenoids, amides, and aldehydes) as reducing agents and solvent systems. The stability/toxicity of nanoparticles and the associated surface engineering techniques for achieving biocompatibility are also discussed. Finally, we covered applications of such synthesized products to environmental remediation in terms of antimicrobial activity, catalytic activity, removal of pollutants dyes, and heavy metal ion sensing.

A magnetically separable Fe 3 O 4 /porous Titanosilicate/g-C 3 N 4 hybrid nanocomposite (FTSCN) has been synthesized by a facile in-situ method. The synthesized nanocomposites are characterized by PXRD, FE-SEM, TEM, BET-Surface area, FT-IR, UV-vis., photoluminescence, magnetic susceptibility and photocatalytic activity. XRD, FE-SEM, TEM, FT-IR, results of FTSCN show that the formation of finely distributed Fe 3 O 4 nanoparticles in the titanosilicate matrix and g-C 3 N 4. BET-surface area shows that the enhancement of surface area on heterojunc-tion. The bandwidth is calculated from diffuse reflectance ultraviolet-visible spectroscopy. The enhancement of electron-hole pair formation is observed fluorescence spectroscopy. The magnetic behaviour is also observed by magnetic susceptibility test of the nanocomposite. FTSCN nanocomposite exhibit improved photodegradation of Rhodamine B sunlight light irradiation. The ideal photocatalytic activity of FTSCN3.5 in presence of sunlight is nearly 4 to 5-fold greater than pure Fe 3 O 4 (FO), pure titanosilicate (TS) and g-C 3 N 4 respectively. We confirmed that the prepared FTSCN3.5 hybrid photocatalyst is very stable even after five consecutive trial runs are observed by XRD spectral data. The enhanced photocatalytic behaviour of the FTSCN3.5 hybrid nanocomposite in the presence of sunlight is because of the synergistic effect of the Fe 3 O 4 , pure titanosilicate and g-C 3 N 4. A plausible, structure of heterojunction, physical and chemical catalytic mechanisms are also proposed.

The quick recombination of charge carriers and the low oxidizing ability of VB holes of g-C 3 N 4 limits its practical application. Herein, we have synthesized a visible-light sensitive Fe(III)-grafted K-doped g-C 3 N 4 /rGO heterostructure photocatalyst to tackle the above problem so as to achieve enhanced photocatalytic activity. The prepared samples were characterized by standard analytical techniques such as XRD, FT-IR, EPR, SEM, TEM, DRS and PL spectroscopy. EPR analysis reveals that the grafted iron exists in +3 oxidation state in the composite material. As compared to pristine g-C 3 N 4 , surface grafted nanocomposite photocatalyst exhibits excellent photocatalytic performance for the degradation of Rhodamine B (RhB), Methylene Blue (MB) and Methyl Orange (MO) under visible light irradiation. The enhanced activity could be attributed to the creation of defect levels in the band gap, shift of absorption band towards the visible region and intimate interfacial interactions between graphene and g-C 3 N 4 , effectively promoting separation of photoinduced charge carriers. The idea to tune the bandgap of graphitic carbon nitride by introducing alkali metal along with its composite formation with graphene could present a new concept to effectively steer the photocatalytic activity.

BACKGROUND: Nano-sized titanium dioxide has potential as a photocatalyst, and doped variants may have different photocatalytic properties. Nano-titanias with a wide range of dopants and compositions can be prepared using continuous hydrothermal flow synthesis (CHFS), but when many samples are made, a large-scale screening test is required to investigate their properties. A range of doped nano-titanias were prepared using a CHFS route, and investigated as powders using a range of photocatalytic test methods. These tests included decolourization of methylene blue (in the presence of oxygen), partial oxidation of a simple alcohol (propan-2-ol) and the degradation of aqueous solutions of dichloroacetic acid. The practicality of the tests for large-scale screening was considered, and the test results were cross-correlated to see if any of them gave similar ranking for activity of the photocatalysts.RESULTS: Two of the tests, namely DCA degradation and propan-2-ol, gave similar rank ordering for the nanopowders, while the MB decolourization results did not suggest a strong correlation with any other test. The addition of metal dopants was observed to produce varying results between different dopants and tests.CONCLUSIONS: Two of the tests, DCA degradation and MB decolourization in visible light, were recommended for further use as screening tests. Copyright © 2009 Society of Chemical Industry

Well crystalline, near-stoichiometric zinc oxide nanostructures of different morphologies are fabricated in large scale, utilizing a simple, cost effective mechanochemical synthesis in absence of solvent. Effects of ionic and nonionic surfactants along with the concentration of hydrolyzing agent on the evolution of nanostructure morphology have been studied. It has been observed that while a cationic surfactant such as Cetyltrimethylammonium Bromide (CTAB) favors the nanostructures to growth along their polar c-axis, a nonionic surfactant such as Polyvinylpyrrolidone (PVP) reduces their preferred c-axis growth. Increase of hydrolyzing agent in the reaction mixture enhances the growth rate of the nanostructures. The nanostructures have been tested for photodegradation of anionic dye molecules such as Methylene Blue (MB). All the nanostructures manifest high photocatalytic performance. Apart from morphology, the specific surface area, crystal plane orientation and the concentration of basic sites at surface are seen to contribute significantly to the photocatalytic performance of the zinc oxide nanostructures.

Photocatalytic materials and additional components, especially promoters, play a pivotal role in the success of photocatalysed environmental remediation processes. To understand the influence of acid promoters in the absence and presence of surfactants, photocatalytic degradation of a model dye rhodamine B (RhB) was studied by UV-photocatalysis (254 nm UV source) with the subsequent addition of each of 0.01 mol dm− 3 of nitric acid (HNO3), sulphuric acid (H2SO4), hydrochloric (HCl), citric acid and acetic acid. Furthermore, the effect of 0.01 mol dm− 3 of sodium hydroxide (NaOH) and sodium carbonate (Na2CO3), as well as surfactants, including the cationic cetrimonium bromide (CTAB), anionic sodium dodecylsulphate (SDS) and non-ionic surfactant tween 80, were analyzed using a UV–Visible spectrophotometer. The kobs. values for photodegradation of RhB under UV-irradiation was heavily dependent on type of acid and base. Pre-micellar, micellar and post-micellar concentrations of surfactants were also analyzed for their effects on the photodegradation of RhB. Concentrations at and above the critical micelle concentration (CMC) were found to suppress the photocatalytic degradation of RhB in the presence of a promoter (HNO3). Micellar solubilization is responsible for the changes in the photocatalytic activity. Nonionic micelles are unable to protect the dye over longer times due to autooxidation process. The resulting degradation products of RhB by radical dotOH were identified by LC-MS and GC–MS analysis and accordingly a schematic degradation pathway was proposed.

Metal oxides (MOs) nanostructures, as visible light active photocatalysts, are widely used in applications such as solar energy conversion, biocidal coating, and environmental remediation. This dissertation investigates the morphological, structural, optical, and photocatalytic properties of some visible light active MO photocatalysts, WO3, CuxO (x = 1, 2), and α-Fe2O3 nanostructures fabricated by the dynamic shadowing growth for above mentioned applications.
Dye adsorption and photodegradation property of WO3 nanorods (NRs) has first been studied. The porous and amorphous WO3 NRs are observed to exhibit superior methylene blue (MB) adsorption capability in aqueous solution due to its large specific surface area and active surface functionality. The adsorption of MB on the surface of WO3 NRs are well described by Langmuir isotherm behavior. Photocatalytic MB degradation with WO3 NRs under UV irradiation is observed to be relatively higher than that under visible light.
The solar water splitting reaction in a photoelectrochemical (PEC) cell and photocatalytic dye degradation behavior of CuxO (x=1,2) NR arrays have been studied under visible light irradiation. Both single phase Cu2O and CuO, and mixed phase Cu2O/CuO polycrystalline NRs are observed to exhibit excellent visible light induced photocatalytic activity for both cationic (MB) and anionic (methyl orange) dye degradation. When used as a photocathode, they also show good PEC performance, especially for the mixed phase Cu2O/CuO NRs. The maximum stable photocurrent density is observed to be -0.24 mA/cm2 under a simulated solar light (AM 1.5G) at an applied bias potential of -0.5 V (versus Ag/AgCl reference electrode). About 20% and 44% incident photon-to-current conversion efficiency are obtained at incident light wavelengths λ = 500 nm and 400 nm respectively.
Finally, both MB degradation and bactericidal activities are studied for the α-Fe2O3 NR arrays and films under the ambient light conditions. The α-Fe2O3 NR arrays annealed at 350 °C exhibit an enhanced bactericidal performance in inactivating E. coli O157:H7, when compared to α-Fe2O3 film. Mathematical models are used to correlate the observed photocatalytic activities.

Surat is the city where maximum textile industries have been found and it represents flourishing textile industries in State of Gujarat. It occupies a very important place in Indian economy in terms of its share and value added and export earnings. Wastewater discharged from these industries contains a variety of polluting substances and the most common and undesirable is dye. Presence of even < 1 ppm dye is harmful to aquatic and terrestrial life so their removal is the alarming point. Usually the removal of dye can be carried out using physical, chemical, and biological methods. But biological methods are quite impactful. Many studies have reported that the microorganisms are powerful biocatalyst for removal of dye containing wastewater. Present study is based on the biodegradation of Azo dye i.e. Methyl red by the isolate Enterobacter cloacae which was isolated from the textile effluent of Sachin GIDC Surat. These strains was identified by molecular and biochemical methods. Degradation was studied with respect to various factors such as pH, temperature, static and shaking conditions, and different carbohydrate and nitrogen source. Results from this research study showed that dye was significantly degraded around 90 to 95% at the optimal factors i.e. pH 7, Temperature 30̊C in static condition and with the carbohydrate source glucose and nitrogen source as urea. These data indicates a unique characteristic of the strain useful for the degradation.

It is highly desired to develop an efficient large surface area CoCrFeO4-based beads sun-light driven photocatalysts with excellent recycling features for degrading high-concentration dyes. Herein, a novel CoCrFeO4 oxide nanoparticles have customarily been synthesized by the
combination of three metals (Co, Cr and Fe) via co-precipitation method in aqueous solution and then millimeter-scale CoCrFeO4 oxide chitosan-composite beads (CoCrFeO4-CB) were prepared by incorporating the CoCrFeO4 in chitosan polymer in basic medium, which makes the
adsorbent easier to separate. The number of optimized nanocomposite beads used for the removal of high-concentration dyes displays 5-time photoactivity enhancement under sun-light irradiation compared to pristine CoCrFeO4. Based on the fluorescence spectra related to theformed •OH amounts, temperature-programmed desorption and electrochemical results, it is deduced that the unprecedented photocatalytic activities are mainly attributed to the large surface
area, and enhanced charge separation from the chitosan as well as its promotion effects on O2 activation. Influencing factors that effect the photocatalytic efficiency of dyes, such as catalyst dose, dyes concentration, time, and the light source was also studied. More importantly, after five catalytic cycles, no evident deactivation was observed, suggesting the satisfactory stability of the investigated photocatalyst. Also, large numbers of superoxides radicals form which is the main active species participate in the degradation of acid black were analyzed using a radical trapping experiment. It is expected that our work could render navigated information for steering toward the design and applications of the CoCrFeO4-based photocatalyst with sun-light
utilization for environmental remediation.

In the current survey, the removal of dye from contaminated water was studied by photocatalytic degradation using TiO2 nanoparticles with respect to pH, TiO 2 dosage, reaction time, temperature and initial dye concentration. TiO 2 nanoparticles were investigated by XRD, FESEM and FT-IR. The RSM was chosen to study the composition effects of input independent factors and one dependent output response (removal efficiency). The P-value (2.2 × 10 −16), F-value (1832), R 2 (multiple R-squared: 0.9985, adjusted R-squared: 0.9972), and lack of fit (0.432) indicate that the reduced full second order model is highly significant for dye removal by TiO 2 nanoparticles. The maximum percentage removal of dye, 90.2%, was achieved at optimum operating conditions including pH=6.5, TiO2 dose (1.2 g L-1), contact time (67.5 min), temperature (40 °C), and dye concentrations (55 mg L-1)), respectively. The maximum removal efficiency was calculated to be 100%, using regression coefficients derived from the model and the Solver "Add-ins". The results indicated that the TiO 2 photocatalyst was very proper for the removal dye from contaminated water, and it had good efficiency in eliminating textile dyes.

Iron and silver nanoparticles were synthesized using a rapid, single step, and completely green biosynthetic method employing aqueous sorghum extracts as both the reducing and capping agent. Silver ions were rapidly reduced by the aqueous sorghum bran extracts, leading to the formation of highly crystalline silver nanoparticles with an average diameter of 10 nm. The diffraction peaks were indexed to the face-centered cubic (fcc) phase of silver. The absorption spectra of colloidal silver nanoparticles showed a surface plasmon resonance (SPR) peak centered at a wavelength of 390 nm. Amorphous iron nanoparticles with an average diameter of 50 nm were formed instantaneously under ambient conditions. The reactivity of iron nanoparticles was tested by the H2O2-catalyzed degradation of bromothymol blue as a model organic contaminant.

In this study, trimetallic catalysts were prepared via the co-precipitation and impregnation methods. In order to investigate the effect of impregnation on the catalytic activity and crystallite size, a trimetallic catalyst, Fe-Ni-Ce, was prepared through the co-precipitation method in one set of experiments, and cerium was impregnated with the Ni-Fe mixture in the final stage of the preparation in another set. Fourier transform infrared spectroscopy was employed to confirm the formation of trimetallic catalysts and the success of the impregnation method. The Brunauer-Emmett-Teller nitrogen adsorption isotherm exhibits a high specific surface area (approximately 39 m2 g−1) for the nanoparticles obtained by the impregnation method. The crystallography and morphology of the trimetallic catalysts thus prepared were characterised by X-ray diffraction and scanning electron microscopy. UV-VIS spectroscopy and methylene blue dye degradation tests were also performed to investigate the catalytic activity of the synthesised catalysts. The crystalline size was found to be smaller for the catalysts prepared by the impregnation method. In addition, the samples synthesised using the cerium impregnation method showed superior activity in the methylene blue dye degradation test. The effect of the catalyst dosage on dye degradation, as well as the effect of the initial dye concentration on the catalyst activity, was also studied for both methods.

Single step hydrothermal synthesis of CdS/Oxide (Oxide = ZnO, Al2O3) was demonstrated and examines their photocatalytic activity in presence of graphene oxide (GO). CdS/Al2O3/GO and CdS/ZnO/GO both exhibits enhanced photocatalytic activity for hydrogen generation with apparent quantum yields (AQY) of 14% and 30% respectively. Moreover, CdS/Oxide/GO displayed efficient photodegradation of organic dye; ~90% for CdS/Al2O3/GO and ~99% for CdS/ZnO/GO within 60 min of time interval. Superior photocatalytic properties are attributed to the enhanced surface area and effective separation of photoinduced charge carriers due to the presence of graphene oxide. The present study highlights the potential application of graphene based materials in the field of energy conversion and environment remediation.

The development of effective photocatalyst through green and eco-friendly approach has become a great concern for the light-induced degradation of organic pollutant dyes. This article reports a simple, cost-effective, and a benign environmental biosynthesis of Ag nanoparticles (NPs) using Cyperus pangorei, a plant extract with three different concentrations of AgNO3 in aqueous media. The synthesized silver nanoparticles were performed ultraviolet–visible spectroscopy (UV–Vis), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), photoluminescence (PL), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The surface plasmon resonance (SPR) peak at 437 nm in UV–Vis spectroscopy confirmed the reduction of Ag+ ions into Ag nanoparticles. FTIR spectra revealed that plant extract could reduce/stabilize/capping to form Ag nanoparticles, and strong PL emission spectra tend to exhibit higher photocatalytic activity. The structural information is derived from XRD and TEM, which can exhibit the FCC structure and polydisperse with the spherical shape. EDX addresses the presence of Ag constitute. XPS confirmed the Ag nanoparticles in characteristic silver peaks, plant extract derivatives, and their oxidative states’ binding energy. The photocatalytic activity of Ag nanoparticles against dye Rhodamine B (Rh-B) under ultraviolet irradiation with periodic interval and pseudo-first-order kinetics were also studied. The obtained results show that the synthesized Ag nanoparticles can degrade dye (Rh-B) up to 86% within 2 h of irradiation time. Furthermore, the present study suggests that the biosynthesized Ag nanoparticles could be potential photocatalysts against various industrial dyes as well as C. pangorei; plant extract can be used to modify and develop more efficient nano-photocatalyst for other application.

The photodegradation of Congo Red (CR) by using nickel calciate nanoparticles (NiCaO2) was investigated. The Nickel calciate nanoparticles (NiCaO2) were prepared by solution combustion method using urea and acetamide as fuels and they were characterized by Scanning Electron Micrograph (SEM), X-Ray Diffraction (XRD), Energy Dispersive X-ray (EDX), Brunauer Emmett-Teller surface area determination and band gap was determined by using UV-absorption spectroscopy. Point zero charge determined by pH drift method. All experiments were carried out under natural sun light. Examined the percentage of degradation of these nanoparticles on Congo Red by varying the dye concentration, pH and catalyst loading. The percentage of degradation was highly efficient in 20ppm dye concentration with pH 4 and constant catalyst concentration 0.4g/100ml for both nanoparticles. This proves that, synthesized nickel calciate nanoparticles are efficient in removing the Congo Red from the waste water.

ZnS loaded TiO 2 (ZnS-TiO 2 ) has been successfully synthesized by precipitation-cum-sol gel method. The photocatalytic activity of (ZnS-TiO 2 ) has been investigated for the degradation of phenol red sodium salt in aqueous solution using UV-A light. In presence of ZnS, there is a shift in the absorbance of TiO 2 in both UV and visible region. ZnS-TiO 2 is found to be more efficient than bare TiO 2 , TiO 2 -P25 and ZnS at pH 6.5 for mineralization of the dye under UV-A light. The effects of operational parameters such as the amount of photocatalyst and dye concentration on photomineralization of the dye have been analyzed. The mineralization has been confirmed by COD measurements. Mechanism of degradation by ZnS-TiO 2 is proposed. The catalyst is found to be reusable.

Abstract The development of effective photocatalyst through green and eco-friendly approach has become a great concern for the light-induced degradation of organic pollutant dyes. This article reports a simple, cost-effective, and a benign environmental biosynthesis of Ag nanoparticles (NPs) using Cyperus pangorei , a plant extract with three different concentrations of AgNO 3 in aqueous media. The synthesized silver nanoparticles were performed ultraviolet–visible spectroscopy (UV–Vis), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), photoluminescence (PL), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The surface plasmon resonance (SPR) peak at 437 nm in UV–Vis spectroscopy confirmed the reduction of Ag + ions into Ag nanoparticles. FTIR spectra revealed that plant extract could reduce/stabilize/capping to form Ag nanoparticles, and strong PL emission spectra tend to exhibit higher photocatalytic activity. The structural information is derived from XRD and TEM, which can exhibit the FCC structure and polydisperse with the spherical shape. EDX addresses the presence of Ag constitute. XPS confirmed the Ag nanoparticles in characteristic silver peaks, plant extract derivatives, and their oxidative states’ binding energy. The photocatalytic activity of Ag nanoparticles against dye Rhodamine B (Rh-B) under ultraviolet irradiation with periodic interval and pseudo-first-order kinetics were also studied. The obtained results show that the synthesized Ag nanoparticles can degrade dye (Rh-B) up to 86% within 2 h of irradiation time. Furthermore, the present study suggests that the biosynthesized Ag nanoparticles could be potential photocatalysts against various industrial dyes as well as C. pangorei ; plant extract can be usto modify and develop more efficient nano-photocatalyst for other application.

A magnetically separable Fe 3 O 4 /porous Titanosilicate/g-C 3 N 4 hybrid nanocomposite (FTSCN) has been synthesized by a facile in-situ method. The synthesized nanocomposites are characterized by PXRD, FE-SEM, TEM, BET-Surface area, FT-IR, UV-vis., photoluminescence, magnetic susceptibility and photocatalytic activity. XRD, FE-SEM, TEM, FT-IR, results of FTSCN show that the formation of finely distributed Fe 3 O 4 nanoparticles in the titanosilicate matrix and g-C 3 N 4. BET-surface area shows that the enhancement of surface area on heterojunc-tion. The bandwidth is calculated from diffuse reflectance ultraviolet-visible spectroscopy. The enhancement of electron-hole pair formation is observed fluorescence spectroscopy. The magnetic behaviour is also observed by magnetic susceptibility test of the nanocomposite. FTSCN nanocomposite exhibit improved photodegradation of Rhodamine B sunlight light irradiation. The ideal photocatalytic activity of FTSCN3.5 in presence of sunlight is ne...

A facile, low cost, and convenient method to fabricate CuxO (x = 1, 2) nanorod (NR) arrays is demonstrated by thermally oxidizing Cu NRs fabricated by oblique angle deposition. The single phase Cu2O and CuO, and mixed phase Cu2O/CuO polycrystalline NRs can be tuned simply by varying the thermal oxidation temperature. These CuxO NRs exhibit excellent visible light photocatalytic activity for both cationic (methylene blue) and anionic (methyl orange) dye degradation. When used as a photocathode, they also show good photoelectrochemical performance, especially the mixed phase Cu2O/CuO NRs. The maximum stable photocurrent density is observed to be 0.24 mA/cm2 under a simulated solar light. Incident photon-to-current efficiencies are found to be 20% and 44% at incident light wavelengths λ = 500 nm and 400 nm, respectively. These results show that the CuxO NRs fabricated through the oxidation method can be a suitable candidate for efficient visible light active photocatalysts for energy applications as well as for wastewater treatment.

The degradation of Acid Blue 111 anthraquinone dye has been studied by the simple electro-assisted Fenton
process and the obtained results were compared to the Fenton process. Ferrous sulphate and hydrogen peroxide
were used and in the electro-assisted Fenton process IrOx electrode was used as the anode. The influence of
hydrogen peroxide and ferrous ion concentration, as well as pH on the processes was investigated. A second-order
kinetic was established and rate constants were determined. The degradation was followed by ultraviolet-visible
spectroscopy, gas and liquid chromatography-mass spectrometry analysis. Mineralization of Acid Blue
111 was confirmed by total organic carbon analysis and ion chromatography analysis. The efficiency and energy
consumption of the processes were calculated. Also, phytotoxicity was studied using the Mung bean seeds.
According to the obtained results, the simple electro-assisted Fenton process was much efficient in the degradation
of Acid Blue 111 dye than the Fenton process.

ZnO nanoparticles with different morphologies were prepared via the biotemplate method. The microstructure of synthesized nanoparticles was found to depend strongly on the type of biotemplate used. Nanoparticles and platelet-like structures with high crystallinity were obtained. The prepared nanostructures were characterized using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), and Brunauer-Emmett-Teller (BET) techniques. Photocatalytic activity of the produced ZnO was examined for methyl orange (MO). High catalytic activity was depicted for ZnO nanoparticles prepared with turmeric powder for the removal of MO dye.

Iron and silver nanoparticles were synthesized using a rapid, single step, and completely green biosynthetic method employing aqueous sorghum extracts as both the reducing and capping agent. Silver ions were rapidly reduced by the aqueous sorghum bran extracts, leading to the formation of highly crystalline silver nanoparticles with an average diameter of 10 nm. The diffraction peaks were indexed to the face-centered cubic (fcc) phase of silver. The absorption spectra of colloidal silver nanoparticles showed a surface plasmon resonance (SPR) peak centered at a wavelength of 390 nm. Amorphous iron nanoparticles with an average diameter of 50 nm were formed instantaneously under ambient conditions. The reactivity of iron nanoparticles was tested by the H(2)O(2)-catalyzed degradation of bromothymol blue as a model organic contaminant.

The anthraquinone dye, C.I. Acid Blue 111, was subjected to electrochemical oxidation using an IrOx electrode and sodium sulphate or sodium chloride as electrolytes. The effects of different operating parameters on the rate of dye decolorization, such as applied current, electrolyte concentration, and initial pH were studied. The dye concentration during the study was followed via ultraviolet-visible spectroscopy. The changes in the dye molecule during electrochemical oxidation were analyzed by Fourier Transformation-infrared spectroscopy. The level of mineralization after electrochemical oxidation was established by total organic carbon analysis.

The azo class of synthetic dyes represents one of the most industrially used dyes as well as a major class of environmental contaminants, which possess one or more azo bonds (-N=N-) along with aromatic rings and sulfonic groups. Due to its recalcitrant nature and toxicity for animals and human beings, the elimination of these dyes from the environment is essential. The present study focuses on the biodegradation of such azo dye, malachite green (MG), through a potent ligninolytic fungus, Aspergillus flavus (F10). Aspergillus flavus (F10) completely decolorized MG (150 mg L−1) within six to eight days in optimized Kirk&#39;s basal medium under static aerobic conditions at pH 5.8. Sucrose and sodium nitrate were efficient carbon and nitrogen sources, respectively. The products obtained after degradation were examined using UV-vis spectrophotometry, Fourier transform infrared spectroscopy, and liquid chromatography-mass spectroscopy. The metabolic intermediate products were identified as N-demethylated and N-oxidized metabolites, including primary and secondary arylamines, which confirms the involvement of laccase and manganese peroxidase in decolorization and degradation of MG. The end products of MG degradation were nontoxic. Aspergillus flavus (F10), immobilized by entrapment on natural and synthetic polymeric matrices was found to be a more efficient degrader of MG as compared to free cells.

The anthraquinone dye, C.I. Acid Blue 111, was subjected to electrochemical oxidation using an IrOx electrode and sodium sulphate or sodium chloride as electrolytes. The effects of different operating parameters on the rate of dye decolorization, such as applied current, electrolyte concentration, and initial pH were studied. The dye concentration during the study was followed via ultraviolet-visible spectroscopy. The changes in the dye molecule during electrochemical oxidation were analyzed by Fourier Transformation-infrared spectroscopy. The level of mineralization after electrochemical oxidation was established by total organic carbon analysis.

Objectives: The objective of this study is to investigate oxidation of three dyes: indigo carmine, methyl violet and 2, 4-dinitrophenol by two-component system Co 2+-H 2 O 2 further analyzing behavior of cobalt in Fenton-like processes. Method: Oxidative degradation was effected in aqueous solutions of dyes under static conditions. Altering concentrations of substrates were analyzed spectrophotometrically. Dynamic light scattering was used to evaluate the condition of cobalt in the solution. The products of oxidative degradation were studied applying the method of nuclear magnetic resonance. Findings: The study shows that hydrogen peroxide in presence of ions Co 2+ is capable of oxidizing indigo carmine. The sulfate ions in the system do not affect the kinetics of the oxidation process. It has been found that oxidation supposedly occurs following the radical mechanism similar to the processes observed in the Fenton system (Fe 2+-H 2 O 2). However, the range of pH values that makes oxidation possible differs considerably from the operating range of the Fenton system: With cobalt ions, the process runs at pH>6. It has been established that intensive oxidation of methyl violet and 2, 4-dinitrophenol also starts when рН value increases up to 6.6-6.8. The formation of cobalt-containing aggregates of cobalt hydroxides in the process of oxidative degradation of indigo carmine has been observed for the first time, i.e. the process occurs in ultra micro heterogeneous system. It has been shown that in presence of cobalt, the substrates are not oxidized in full; the products of oxidation are represented by a complicated set of organic compounds. Applications/Improvements: In practice, functioning at higher рН values is an important advantage of the cobalt-containing system as compared to the iron-containing one.

Nanoparticle (NP) catalysts are widely used for removal of dyes for single use, but there is an acute need for developing catalysts with high efficiency and reusability for mixed dyes. Here we first optimized the process (reactant proportion, temperature, time, and pH) for biosynthesis of monometallic Ag, Au and bimetallic Au–Ag alloy NP catalysts using Polyalthia longifolia leaf extract. The biosynthesized NP catalysts were characterized by UV-vis, DLS, Zeta potential, TEM and EDX study while the probable biomolecules responsible for biosynthesis were identified by FTIR and GC-MS/MS analysis. The NPs are found to be mostly spherical in shape (size 5–20 nm) with prolonged stability. We evaluated their chemo-catalytic performance through degradation of dyes (methyl orange, methyl violet, methylene blue) in individual and ternary mixture in presence of NaBH4. The degradation percentage (80.06–96.59% within 5 min), degradation kinetics (k = 0.361–1.518 min–1), half-life (T50 = 0.457–1....

Photocatalytic activity of low band gap hydrogenated HfO 2 doped TiO 2 (H-HfO 2 /TiO 2), HfO 2 doped TiO 2 (HfO 2 /TiO 2) and TiO 2 (pristine) were investigated by photocatalytic degradation of five different industrial dyes. The current study envisages the effect of doping hydrogen and HfO 2 up on TiO 2 for photocat-alytic degradation of different chemically structured dyes. Methylene Blue attains fast degradation efficiency of 90%, within 10 min of the reaction due to high photocatalytic adsorption and degradation over the rough TiO 2 surface. Effect of pH on dye degradation is observed, leading to disintegration and mineralization.

Increasing textile industries in the last few decade has resulted in the discharge of very large quantities of complex chemical dye to the water system. This has affected the ecological and biological balance causing immense destruction to the nature. In this work, azo dye (Orange G 16) degradation studies by Pseudoalteramonas sp. were investigated. From the experiments, Pseudoalteromonas species degraded the Orange G 16 azo dye at a short time span within 3 h. The assay time for azoreductase activity was standardized, and maximum activity was observed at 24th. The protein concentration was estimated at three different stages of dye degradation. First stage is before addition of dye, second stage is 3 h after addition of the dye during which the dye had completely decolourized, and the third stage is 18 h after the addition of dye. From the study, it was observed that protein concentration was higher in the 24-h sample which has been induced with Orange G 16 azo dye having a concentration of 0.92 mg/ml. While comparing the total activity and specific activity of the enzyme for three samples, it was observed that the activity was higher at the 24th s and then subsided gradually. Thus, Pseudoalteromonas sp. is found to be efficient in degrading azo dyes because of its potential to degrade the dyes rapidly which also has a higher azoreductase activity.

The anthraquinone dye, C.I. Acid Blue 111, was subjected to electrochemical oxidation using an IrOx electrode and sodium sulphate or sodium chloride as electrolytes. The effects of different operating parameters on the rate of dye decolorization, such as applied current, electrolyte concentration, and initial pH were studied. The dye concentration during the study was followed via ultraviolet-visible spectroscopy. The changes in the dye molecule during electrochemical oxidation were analyzed by Fourier Transformation-infrared spectroscopy. The level of mineralization after electrochemical oxidation was established by total organic carbon analysis.

In this study, we report the synthesis of a 3-dimensional (3D) hierarchical Bi3O4Cl/Bi5O7I (BOC/BOI) heterostructure for the photocatalytic degradation of Rhodamine-B (RhB) dye and colorless Bisphenol-A (BPA) pollutant under visible light. The heterostructure was prepared using in situ solvothermal and calcination methods. BOC/BOI exhibits a 3D hierarchical structure constructed with thin nano-platelets. The photocatalytic performance of the BOC/BOI photocatalyst demonstrated that the degradation efficiencies of RhB and BPA were 97% and 92% after light illumination within 90 and 30 min, respectively. In comparison, bare BOC and BOI efficiencies were only 20% and 10% for RhB dye, respectively, and 2.3% and 37% for BPA aqueous pollutants, respectively. Moreover, radical trapping measurements indicated that • O2 − and • OH radicals played prominent roles in RhB and BPA degradation into mineralization. Analysis of band structures and photochemical redox reactions of BOC/BOI revealed a Z-scheme charge transfer between BOC and BOI by an internal electric field formed at the interface. Therefore, the highly improved photocatalytic performance of the BOC/BOI heterostructure is attributed to the synergetic effects of large surface area, high visible-light absorption, and the enhanced separation and transport of photo-excited electron-hole pairs induced by the hierarchical and Z-scheme heterojunction of the BOC/BOI.

In this paper, we report the preparation of visible-light active direct Z-scheme Cu2O/WO3 nanocomposite photocatalyst by a solid-state reaction avoiding the otherwise inevitable formation of CuWO4 phase in wet syntheses. Structure, morphology, and thermal and optical properties of prepared WO3 nanoplatelets decorated by Cu2O were investigated by XRD, Raman spectroscopy, SEM/TEM, combined thermogravimetric (TG)/differential scanning calorimetry (DSC) analysis, and UV–VIS spectroscopy. The photocatalytic performance of the prepared samples under UV and visible light was studied through monitoring discoloration of methylene blue under illumination by selected wavelengths, allowing for the distinguishing between the contributions of the two semiconductive components. Experimental results showed that the decoration of WO3 nanoplates by Cu2O nanoparticles led to an improvement in photocatalytic performance, regardless of used LED (Light-Emitting Diode) wavelength, even at low concentratio...

By using the glancing angle deposition technique and post-deposition annealing, Fe2O3–TiO2 core–shell nanorod arrays with specific crystalline states can be designed and fabricated. The Fe2O3–TiO2 core–shell samples annealed at temperatures greater than 450 °C formed α-Fe2O3 and anatase TiO2, and showed higher catalytic efficiency for the degradation of methylene blue (MB) under visible light illumination when compared with pure anatase TiO2 or α-Fe2O3 nanorod arrays. Solar conversion of carbon dioxide and water vapor in the presence of Fe2O3–TiO2 core–shell nanorod arrays was also investigated. Carbon monoxide, hydrogen, methane, and methanol along with other hydrocarbons were produced after only several hours’ exposure under ambient sunlight. It was determined that the core–shell structure showed greater efficiency for solar CO2 conversion than the pure TiO2 nanorod arrays.

In this study, we report the synthesis of a 3-dimensional (3D) hierarchical Bi3O4Cl/Bi5O7I (BOC/BOI) heterostructure for the photocatalytic degradation of Rhodamine-B (RhB) dye and colorless Bisphenol-A (BPA) pollutant under visible light. The heterostructure was prepared using in situ solvothermal and calcination methods. BOC/BOI exhibits a 3D hierarchical structure constructed with thin nano-platelets. The photocatalytic performance of the BOC/BOI photocatalyst demonstrated that the degradation efficiencies of RhB and BPA were 97% and 92% after light illumination within 90 and 30 min, respectively. In comparison, bare BOC and BOI efficiencies were only 20% and 10% for RhB dye, respectively, and 2.3% and 37% for BPA aqueous pollutants, respectively. Moreover, radical trapping measurements indicated that •O2− and •OH radicals played prominent roles in RhB and BPA degradation into mineralization. Analysis of band structures and photochemical redox reactions of BOC/BOI revealed a Z-sc...

The azo class of synthetic dyes represents one of the most industrially used dyes as well as a major class of environmental contaminants, which possess one or more azo bonds (-N=N-) along with aromatic rings and sulfonic groups. Due to its recalcitrant nature and toxicity for animals and human beings, the elimination of these dyes from the environment is essential. The present study focuses on the biodegradation of such azo dye, malachite green (MG), through a potent ligninolytic fungus, Aspergillus flavus (F10). Aspergillus flavus (F10) completely decolorized MG (150 mg L−1) within six to eight days in optimized Kirk&#39;s basal medium under static aerobic conditions at pH 5.8. Sucrose and sodium nitrate were efficient carbon and nitrogen sources, respectively. The products obtained after degradation were examined using UV-vis spectrophotometry, Fourier transform infrared spectroscopy, and liquid chromatography-mass spectroscopy. The metabolic intermediate products were identified as N-demethylated and N-oxidized metabolites, including primary and secondary arylamines, which confirms the involvement of laccase and manganese peroxidase in decolorization and degradation of MG. The end products of MG degradation were nontoxic. Aspergillus flavus (F10), immobilized by entrapment on natural and synthetic polymeric matrices was found to be a more efficient degrader of MG as compared to free cells.