Degradation Of Orange Research Articles

An environmentally-friendly approach to monovalent Cu-doped ZnS: Physicochemical characterization and photocatalytic activity

Certain semiconducting species suffer from the lack of optical activity in the visible region of electromagnetic spectrum, due to large band gap. The integration of various dopants has been widely used in order to generate additional electron transitions and subsequently lead to red-shifted absorption spectrum and enhanced photon harvesting in the visible-NIR region. Herein, a facile two-step environmentally-friendly approach was employed to integrate monovalent Cu species onto ZnS lattice. The study was set to assess the effect of Cu doping in Zinc Sulfide lattice on optical and photocatalytic properties. The theoretical weight fraction of the dopant ranged between 0% and 50%. The physicochemical characterization of either neat semiconductors (ZnS and Cu2O) or Cu-doped ZnS hybrids was performed by using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Raman, X-ray photoelectron spectroscopy (XPS), X-ray induced Auger electron spectroscopy (XAES) and Diffuse reflectance spectroscopy (DRS). XPS provided some enhanced understanding about the chemical speciation of the hybrid materials. This information was strongly supported by Raman analysis. The optimized Cu-doped ZnS hybrid demonstrated enhanced photocatalytic activity towards the degradation of Orange G dye, under UV irradiation.

Degradation of Orange G Using PMS Triggered by NH2-MIL-101(Fe): An Amino-Functionalized Metal-Organic Framework.

As an azo dye, OG has toxic and harmful effects on ecosystems. Therefore, there is an urgent need to develop a green, environmentally friendly, and efficient catalyst to activate peroxymonosulfate (PMS) for the degradation of OG. In this study, the catalysts MIL-101(Fe) and NH2-MIL-101(Fe) were prepared using a solvothermal method to carry out degradation experiments. They were characterized by means of XRD, SEM, XPS, and FT-IR, and the results showed that the catalysts were successfully prepared. Then, a catalyst/PMS system was constructed, and the effects of different reaction systems, initial pH, temperature, catalyst dosing, PMS concentration, and the anion effect on the degradation of OG were investigated. Under specific conditions (100 mL OG solution with a concentration of 50 mg/L, pH = 7.3, temperature = 25 °C, 1 mL PMS solution with a concentration of 100 mmol/L, and a catalyst dosage of 0.02 g), the degradation of OG with MIL-101(Fe) was only 36.6% within 60 min; as a comparison, NH2-MIL-101(Fe) could reach up to 97.9%, with a reaction constant k value of 0.07245 min-1. The NH2-MIL-101 (Fe)/PMS reaction system was able to achieve efficient degradation of OG at different pH values (pH = 3~9). The degradation mechanism was analyzed using free-radical quenching tests. The free-radical quenching tests showed that SO4•-, •OH, and 1O2 were the main active species during the degradation of OG.

In situ growth of CuO on porous geopolymer spheres as green catalysts for enhanced peroxymonosulfate‐activated degradation of Orange I

AbstractIn this study, in situ growth of CuO on the surface of porous geopolymer catalyst spheres (GC) was prepared through a simple method for the activation of peroxymonosulfate (PMS) to degrade Orange I (OI) in water. GC‐0.01 exhibited an excellent performance with more than 95% degradation of OI within 30 min. The effects of PMS concentrations, catalyst dosage, Cl−, HCO3−, and humic acid (HA) on OI degradation in the GC‐0.01/PMS system were systematically investigated. The study of the mechanism showed that PMS combined with the catalyst to generate complexes on the surface of the spheres, which could degrade OI through an electron transfer pathway. In addition, a variety of reactive oxygen species, mainly 1O2, were also present in the GC‐0.01/PMS system, which could also degrade OI. This work provides new insight into the application of oxide‐modified geopolymers in the activation of PMS for water purification applications.

Thin film coating of hydrothermally grown ternary nanocomposites for photocatalytic degradation of environmental pollutants

Environment and pollution have become almost inseparable due to the contamination of each and every sector as a consequence of industrialization. Wastewater treatment using radicals are the best source of oxidizing agents. Since, semiconductor nanomaterials are excellent photocatalysts which produce radicals upon light irradiation. The photocatalyst prepared as nanopowders were investigated by coating them as thin films on glass slide by a spin coating technique as they are better candidates for photocatalytic degradation of persistent organic pollutants (POP). Hydrothermally grown ternary nanocomposite containing ZnO/CeO2/rGO was named as binary metal oxide/rGO (BMON) was found to be in a particle size of less than 100 nm. The XRD and FT-IR analysis proved the crystallinity and M-O stretching in the prepared nanocomposite. The glass slides coated with the BMON (BMON-GS) were studied for their photocatalytic efficiency on the degradation of Orange G dye under solar light irradiation. The prepared was also studied for its reusability and was found to maintain its activity even up to 5 cycles. Hence, it would be a better candidate and highly economical alternative for treatment of industrial wastewater

Heterogeneous vs homogenous photocatalysis: what dominates in the degradation of methyl orange and methylene blue mixtures?

Photocatalysis has been oft proposed as a green solution for pollution remediation, however, majority of the existing literature only studies the degradation of solitary analytes. The degradation of mixtures of organic contaminants is inherently more complicated due to a variety of photochemical processes that occur in parallel. Here, we describe a model system comprised of methylene blue and methyl orange dyes whose degradation carried out by two common photocatalysts, P25 TiO2 and g-C3N4. With P25 TiO2 as the catalyst, the degradation rate of methyl orange slowed by 50% when degraded in a mixture compared to when alone. Control experiments with radical scavengers showed this to occur due to competition between the dyes for oxidative photogenerated species. In the presence of g-C3N4, methyl orange's degradation rate in the mixture increased by 2300% due to two homogeneous photocatalysis processes sensitized by methylene blue. Homogenous photocatalysis was found to be fast relative to heterogeneous photocatalysis by g-C3N4 but slow relative to photocatalysis by P25 TiO2 and explains the change observed between the two catalysts. Changes in dye adsorption to the catalyst when in a mixture were also explored but not found to coincide with changes in degradation rate.

Degradation of Orange G by UV/TiO2/IO4 ‾process: Effect of operational parameters and estimation of electrical energy consumption

In the present study, the degradation of an azo dye Orange G (OG) by the UV/TiO2/periodate (IO4‾) process has been investigated. OG was totally disappears within 10 min by the UV/TiO2/IO4‾compared to UV alone, UV/TiO2 or UV/IO4‾. A synergistic effect has been obtained when combining the UV/TiO2 and the UV/IO4‾systems, resulting in positive interactions between both processes. Experiments conducted with specific hydroxyl radical scavengers, show that despite the inhibition effect observed, complete degradation has been achieved beyond 10 min, demonstrating that the degradation is not only initiated by hydroxyl radical, but also by other reactive entities; the involvement of iodate radical is confirmed with the use of chromium species as a competitor with periodate ions for the photogenerated electron at the conduction band. The operating parameters influencing the degradation process such as initial dye concentration, initial periodate concentration, light intensity/wavelength and initial pH solution have been explored. The presence of inorganic ions such as chloride, bromide, sulphate, carbonate and bicarbonate ions in the irradiated solution show reverse effects depending on the concentration used. The OG degradation in different water matrices is found to be sensitive to the presence of different species and their nature. Chemical oxygen demand (COD) has been partially removed after 10 min of treatment, and then this COD abatement stabilized, indicating the strength of the by-products from dye degradation by the UV/TiO2/IO4‾ system during the treatment time. The electrical energy consumption is estimated at 2.21kWhm‾3/Order. The results obtained indicate that the UV/TiO2/IO4‾ process could be used as a hybrid process to the treatment of dye contaminated water.

One-pot fabrication of magnetic biochar by FeCl3-activation of lotus seedpod and its catalytic activity towards degradation of Orange G

An advanced magnetic biochar (MBC) was facilely prepared via one-pot FeCl3-activation of lotus seedpod. Simultaneous carbonization, activation, and magnetization formed magnetic Fe3O4 nanoparticles and nanowires over the biochar base. The specific surface area (SBET) and the total pore volume (Vtotal) of MBC were 349 m2 g−1 and 0.31 cm3 g−1, which were 2.0-fold and 3.9-fold higher than those of biochar, respectively. In addition, the saturation magnetization of MBC reached 6.94 emu g−1, facilitating its magnetic separation and recovery. In heterogeneous Fenton-like catalytic oxidation, 0.40 g l−1 MBC decolorized 100% Orange G and reduced 58% COD by 350 ppm H2O2 within 120 min. The degradation kinetics were calculated with different MBC samples and reactions followed pseudo-first-order kinetics with the highest rate constant of 0.034 min−1. Moreover, the catalytic activity dropped by only 6.4% after four reuse cycles, with negligible iron leaching of 1.31–1.44 mg l−1. Based on these results, MBC could be a low-cost, highly effective, and relatively stable catalyst for treating Orange G in wastewater.

Nanoarchitectonics of AgBr/4A Zeolite Composites with Enhanced Photocatalytic Properties Under Visible Light

AgBr/zeolite photocatalysts with different mass ratios were synthesized by depositing AgBr on the surface of 4A zeolite via the one-step precipitation method. AgBr/zeolite with mass ratios of 1:1 exhibited the highest photocatalytic activity, resulting in the complete degradation of the methyl orange (MO) dye under visible-light irradiation for 30[Formula: see text]min. The photocatalysts were characterized by N2 adsorption–desorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–Vis diffused reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The AgBr particles around 4A zeolite were smaller than pure AgBr. The specific surface area of 1:1 AgBr/zeolite was much larger than that of pure AgBr, which indicates that 1:1 AgBr/zeolite possessed more active sites. The photocatalytic stability of 1:1 AgBr/zeolite was investigated, and MO degradation rate of 90.4% was achieved after five cycling runs. The trapping experiments showed that hydroxyl radical ([Formula: see text]OH), superoxide radical ([Formula: see text]O[Formula: see text]), and hole (h[Formula: see text]) were the reactive species responsible for removing MO, and h[Formula: see text] played a key role in MO removal. A possible reaction mechanism in AgBr/zeolite photocatalytic system for MO degradation was proposed.

Enhanced peroxymonosulfate activation for Orange I degradation by g-C3N4/AgFeO2 composite in water

The construction of heterogeneous catalysts with high efficiency is significant for the degradation of persistent contaminants. Herein, the g-C3N4/AgFeO2 composite was fabricated and its composition, morphology and structure were systematically characterized. g-C3N4/AgFeO2 exhibited boosting peroxymonosulfate (PMS) catalytic performance on the degradation of Orange I (OI) than pure AgFeO2. It was optimized that the elimination of OI could be enhanced to 91%, with a kinetic rate of 0.076 min−1. Such enhancement was attributed to the increment of low-valent metal species (Ag0/Ag+, Fe2+/Fe3+) on AgFeO2 surface after coupling with g-C3N4, additionally, the synergy of g-C3N4 and AgFeO2 endowed the g-C3N4/AgFeO2 composite with higher conductivity and more electron transfer, thereby promoting effective PMS decomposition. The leaching of metal ions in the g-C3N4/AgFeO2/PMS system was suppressed, which brought superior reusability and stability. It was verified that 1O2、O2•-、SO4•- and •OH acting as the key reactive oxygen species contributed to the OI removal. Our findings provided valuable insights into the design of efficient and stable g-C3N4-based organometallic composites for advanced oxidation processes.

A new melamine-based Cu(I) coordination polymer with an excellent photocatalytic activity, therapeutic and nursing effects on the blood glucose regulation

A novel Cu(I) coordination polymer [Cu2(MA)2Cl2]n (1, MA is melamine) is reported here. It is synthesized by hydrothermal reactions of CuCl and MA. Moreover, this compound shows an excellent photocatalytic effect for methyl orange and methyl blue degradation. The biological activity of the compound on the blood glucose regulation is evaluated. First of all, real time RT-PCR is exploited to measure the aldose reductase activity. Then, the blood glucose concentration released into the plasma is determined. The CCK-8 is used to measure the toxicity of the new compound on normal liver cells.

Mycoremediation and toxicity assessment of textile effluent pertaining to its\xa0possible correlation with COD

Globally, textile industries are one of the major sectors releasing dye pollutants. This is the first report on the positive correlation between toxicity and chemical oxygen demand (COD) of textile effluent along with the proposed pathway for enzymatic degradation of acid orange 10 using Geotrichum candidum within a very short stretch of time (18 h). Removal efficiency of this mycoremedial approach after 18 h in terms of chemical oxygen demand, biological oxygen demand, total suspended solids, salinity, color and dye concentration in the treated effluent reached to 98.5%, 56.3%,73.2%, 64%, 89% and 87% respectively. Also there was a decrease in pH of the treated effluent. FTIR analysis of the treated effluent confirmed biodegradation. The LCMS analysis showed the degradation of acid orange 10, which was confirmed by the formation of two biodegradation products, 7-oxo-8-iminonapthalene-1,3-disulfonate and nitrosobenzene, which subsequently undergoes stepwise hydrogenation and dehydration to form aniline via phenyl hydroxyl amine as intermediate. The X-ray diffraction studies showed that heavy metal content in the treated effluent has reduced along with decrease in % crystallinity, indicating biodegradation. The connection between toxicity and COD was also inveterated using Pearson’s correlation coefficient. Further the toxicological studies indicated the toxicity of raw textile effluent and relatively lower toxic nature of metabolites generated after biodegradation by G. candidum.

Construction of ZnxCd1−xS/CeO2 composites for enhanced photocatalytic activity and stability by chemical precipitation method

Development photoinduced photocatalysts is a significant approach to improve photocatalytic activity and stability. Herein, we successfully prepared [Formula: see text] composites by a facile method. It is found that the [Formula: see text] composites show significant enhancement in photocatalytic activity for methyl orange (MO) degradation under visible and UV light irradiation. The degradation efficiency reaches up to 3.7 times higher than that of pure [Formula: see text] under visible light irradiation. Moreover, the [Formula: see text] samples have almost no loss of photocatalytic activity after five recycles, indicating good photocatalytic stability of the samples. The attractive photocatalytic activity of the [Formula: see text] samples could b e attributed to the robust charge carriers transfer and separation.

Bi-Template Assisted Sol-Gel Synthesis of Photocatalytically-Active Mesoporous Anatase TiO2 Nanoparticles

Sol-gel mesoporous titanium dioxide powders have been synthesized from chitosan and/or hexadecyltrimethylammonium bromide (HDTMA) and characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA) and N2 adsorption-desorption measurements. The photocatalytic performance of the synthesized meso-TiO2 powders was optimized based on the central composite design (CCD) of methyl orange (MO) degradation under UV light irradiation. The maximum MO degradation was 62.3% over a period of 60 min. Oxides produced using the binary chitosan and HDTMA template (C,H-TiO2) exhibited the relatively higher surface area (99.5 m2/g), smaller crystal size (12.78 nm), narrower band-gap energy (2.92 eV) and higher photocatalytic rate constant (0.0112 min–1) than as those from chitosan (C/TiO2) or HDTMA (H/TiO2) as the template.

The Role of PEG 6000 and PVP as Stabilizing and Surfactant Agents in the Photoelectrochemical Properties of BiVO4 Monoclinic Structure

Nanocrystalline BiVO4 on monoclinic phase was obtained by a modified-solution combustion synthesis (SCS) using poly(ethylene glycol) (PEG 6000) and polyvinylpyrrolidone (PVP) as stabilizing and surfactant agents, respectively. An active photoanode was built using a simple procedure by dip-coating deposition process on fluorine-doped tin dioxide (FTO). The structure, morphology and optical properties of FTO/BiVO4 photoanode were evaluated by means of X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and diffuse reflectance UV-Vis spectroscopy. The photoelectrochemical performance measurements were carried out by linear sweep voltammetry (LSV), chronoamperometry and electrochemical impedance spectroscopy (EIS) under InGaN blue light emitting diode (LED) illumination condition (about 450 nm). In Na2SO4 electrolyte solution, the electrode has presented better photoelectroactivity than in NaNO3 solution, as evidenced by photoelectrochemical parameters such as: the highest photocurrent density (js) value, cathodic shifts of the onset potential (OP) and lower charge-transfer resistence (Rct). In the methyl orange (MO) degradation reaction the FTO/BiVO4 electrode has presented high photoelectroactivity, where the estimated kinetic constant rate (kobs) is 4.74 × 10−3 and 7.54 × 10−3 min−1 in NaNO3 and Na2SO4 solutions, respectively. This remarkable performance of the as-prepared electrode is due to the morphological BiVO4 structure,with elongated-shape nano-sized domain particles, besides the considerable porosity and roughness levels on electrode surface.

Efficient activation of peroxymonosulfate and degradation of Orange G in iron phosphide prepared by pickling waste liquor

In this study, the low-cost preparation of iron phosphide by using pickling waste liquor as the initial material was performed through a two-step reaction. The degradation of Orange G was evaluated using iron phosphide coupled with peroxymonosulfate to construct a catalytic system. The removal efficiencies of Orange G and total organic carbon reached 97.4 and 58.4% at 60 min, respectively. Iron phosphide has dual-catalysis centers for the activation of PMS. Multiple free radicals (e.g., SO4•−, HO•, SO5•−, and O2•−) and singlet oxygen were involved in the pollutant degradation, of which sulfate radicals played the main role. The iron phosphide catalyst exhibited excellent recycling stability, and its catalytic efficiency reached 95% after five cycles. In summary, the Fe2P/PMS system—as a Fenton-like catalytic system—has certain advantages, including low cost, high efficiency, sufficient reusability, and good stability, all of which are favorable for its practical application.

Photocatalytic activity enhancement for removal of dye molecules based on plasmonic Ag grafted TiO2 nanocubes under visible light driven

Introduction: Finding a novel photocatalyst for photocatalytic degradation operating in the wavelength range from UV to visible light has been considered a great potential for environmental remediation. Herein, TiO2 nanocubics (NCs) decorated Ag nanoparticles (NPs) with various concentrations were developed.
 Methods: The crystal structure, morphological and chemical characteristics of prepared photocatalysts were thoroughly analyzed by a series of main analyses (X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), and UVVis spectra).
 Results: The results revealed that a significantly promoting visible-light photocatalytic behavior of TiO2NCs@Ag photocatalyst was observed. The photocatalytic methyl orange (MO) degradation of the as-synthesized Ag anchored TiO2NCs photocatalyst (85% and 62% under UV light and visible light, respectively) exhibited outstanding photocatalytic efficacy compared with pristine TiO2 NCs. The achieved results could be assigned to the synergistic effects between TiO2NCs and Ag- NPs, leading to enhanced charge carrier separation and improved absorption ability in visible-light response.
 Conclusion: This work facilitates designing and developing high-efficiency heterostructure photocatalysts for practical works related to environmental deterioration.

Degradation of Orange G and Malachite green dyes under visible light irradiation: Double layered core-shell nanoparticle as an efficient photocatalyst

Core-shell nanomaterials have emerged as a frontier area of focus in materials chemistry and catalysis. Here, we have explored the photocatalyst potential of a double layered core-shell material comprising a rare earth material as core and silica, zinc oxide as the subsequent shell materials. The prepared core-shell has average particle size of 40-60 nm, and the material has been characterized by FTIR, XRD, UV-DRS and FESEM techniques. The band gap energy of prepared material is 2.82 eV. The photocatalytic activity has been tested against Orange-G and Malachite green dye under visible light irradiation. A comparison for degradation of azo and non-azo dye has been elucidated. Preliminary studies with varying pH, catalyst dosage and initial dye concentration have been done to determine the optimum parameters for photocatalytic activity. The kinetic studies follow pseudo-first-order pathway. The prepared core-shell nanomaterial is found efficient for degradation of non-azo dye compared to azo dye. Both the materials show better activity than pristine ZnO. The photocatalyst is found to be environmentally benign with reusability even up to the third cycle of reuse.

Constructing an efficient p–n heterojunction photocatalyst CaFe2O4/Fe2O3 nanocomposite for degradation of methyl orange

As the global environment continues to deteriorate, a technology is urgently needed to eliminate the pollution caused by organic dyestuffs in the environment. Although nano-Fe2O3 photocatalyst has developed greatly in the field of organic degradation, until now, the degradation efficiency cannot satisfy the demands. This work addresses imperative need by constructing an efficient p–n heterojunction photocatalyst CaFe2O4/Fe2O3 nanocomposite for improving the methyl orange (MO) degradation efficiency of nano-Fe2O3. Here, the p-CaFe2O4/n-Fe2O3 nanocomposite was prepared by using the two-step process of hydrothermal method and co-precipitation. The degradation performance of as-developed nanocomposite was tested by altering the experimental parameters including different mass ratio of p-CaFe2O4 and n-Fe2O3, photocatalyst dosage, H2O2 volume, initial concentration of MO and pH, and degradation intermediates were analyzed by HPLC and MS. Experimental results indicated the degradation efficiency of prepared sample was up to 99% at 60 min under the optimized conditions, meanwhile, it showed high removal ability after five repeated utilizations. Furthermore, the photocatalytic mechanism was systematically explored based on degradation intermediates. Overall, the nanocomposite photocatalyst was not only designed with using cheap and abundant materials via a simple route, but also exhibited outstanding photocatalytic activity, which will supply a new possibility to effectively deal with the large volume organic pollutants from the textile industry.

Insight into the degradation of Orange G by persulfate activated with biochar modified by iron and manganese oxides: Synergism between Fe and Mn

In this study, sludge-derived biochar (SDBC) loaded with metal oxides was successfully synthesized via a simple impregnation method, including monometallic-based SDBC (Fe, F-SDBC; Mn, M-SDBC) and bimetallic-based SDBC (Fe and Mn, FM-SDBC). Results demonstrated that FM-SDBC possessed higher activation capacity than F/M-SDBC. The degradation of Orange G (OG) under different pH were explored. Leaching of metal ions and cycling test showed that FM-SDBC possess extraordinary stability and reusability during repeated activation of persulfate (PS). It was evidenced by quenching studies that both SO4·－ and ·OH were generated in FM-SDBC/PS. The XPS spectra of Fe 2p and Mn 2p before and after reactions indicated that the activation of PS on FM-SDBC was in company with the redox cycling of Fe and Mn species. Through the kinetics study, the contribution of Mn occupied the dominant position at the beginning, and Fe did in subsequent activation process in FM-SDBC/PS system. Synergistic mechanism between Fe and Mn in FM-SDBC could be attributed to (1) mutual electron transfer between Fe and Mn; (2) the formation of Fe-Mn bonds, which facilitated electron transfer between Fe and Mn to some extent. Based on the synergistic mechanism aforementioned, bimetallic-based biochar, especially FM-SDBC prepared in this study, had the benefits of high efficiency, stability, reusability and waste control by waste, which provided new insights into sulfate radical (SO4·－)-based advanced oxidation processes in practical application.

Degradation of Orange I by the zero-valent iron/hydrogen peroxide system

The zero-valent iron/hydrogen peroxide system was very effective for the oxidative degradation of high concentration Orange I solution. The effects of Orange I initial concentration, hydrogen peroxide concentration, zero-valent iron dosage and pH value of solution on the degradation of Orange I were studied in this article. The concentration of iron ion, pH value and the content of Orange I in the reaction solution were determined by UV-VIS spectrophotometer and pH meter, respectively. The intermediate degradation products were determined by LC-MS. The experimental results showed that the Orange I solution with high concentration could be effectively degraded with low hydrogen peroxide concentration and iron powder dosage under acid condition. In addition, it can be speculated that in the process of degradation, Orange I was first dissociated into 4-(4-hydroxy-1-naphthylazo) benzenesulfonate, and then its chromophore was oxidized and broken, decoloring the reaction solution, followed by the generation to benzene sulfonate, nitrogen and 1, 4-naphthoquinone. After that, 1, 4-naphthoquinone was further oxidized to phthalate.