Oxidation Of Dye Research Articles

Atmospheric Plasma Supported by TiO2 Catalyst for Decolourisation of Reactive Orange 16 Dye in Water.

PurposeEvery advanced oxidation process (AOP) has its limitations in water purification. Novel designs with simultaneous application of different AOPs can offer better solutions for cleaner water.MethodsWe have comparatively studied two advanced oxidation processes (AOPs) on decolourisation of Reactive Orange 16 (RO 16) azo dye pollutant from water: gas plasma treatment by low power atmospheric pressure plasma using novel plasma needle configuration, and semiconductor heterogeneous photocatalysis using titanium dioxide (TiO2) nanopowders. Additionally, simultaneous application of two advanced oxidation processes on azo dye decolourisation was studied.ResultsIt was found that plasma treatment is very efficient system for the dye removal even for low flow rates (1 slm) of the Ar as feed gas. The presence of 10% of O2 in Ar flow intensified dye oxidation process and shortened required time for total decolourisation. When plasma and catalyst were simultaneously applied, TiO2 was activated with a few Watts plasma source as well as 300 W UV lamp source. The synergic effect of two AOPs was more pronounced for higher feed gas flow rates, resulting in improved decolourisation efficiency.ConclusionPlasma needle can efficiently remove Reactive Orange 16 azo dye from water with a power consumption of only few Watts. With the addition of TiO2 the removal efficiency is significantly improved.Graphic

Ultrasound Accelerated Oxidation of Organic Dyes by a Micron‐Sized Copper/Peroxomonosulfate System

AbstractExperiments on the degradation of acid orange 7 (AO7) using micron‐sized zero‐valent copper (ZVC) are conducted in acidic aqueous solution under ultrasonic (US) irradiation. The US/ZVC/peroxymonosulfate (PMS) process for AO7 degradation is significantly better than that of an independent system. Based on the characterization of ZVC, it is observed that the corrosion speed of ZVC increases after ultrasound, owing to which a greater amount of Cu+ (0–3.03 mg L−1) and Cu2+ are produced. Exposure to US irradiation increases the available surface area of the catalysts to generate many new reactive sites for the degradation process. The AO7 degradation rate after the addition of a new copper reagent—neocuproine hemihydrate—from 6.33% to 100% proved that Cu+ is the main activator of PMS. Results indicated that free radicals (OH• and SO4−•) act as activators of PMS in the process. And higher ultrasound power, lower solution pH, and a larger ZVC dose are favorable for AO7 removal.

Hourglass-type polyoxometalate-based crystalline materials as efficient cooperating photocatalysts for the reduction of Cr(vi) and oxidation of dyes

Hourglass-type polyoxometalate-based crystalline materials exhibit efficient photocatalytic activities towards simultaneous photocatalytic Cr(vi) reduction and organic MB oxidation.

Preparation of a novel and highly stable Al-Fe loaded sepiolite catalyst for the CWPO of methyl orange: Optimization of physicochemical parameters, kinetics and thermodynamics studies

Al-Fe loaded sepiolite catalysts with different active metal ratio have been synthesized using a Turkish sepiolite sample from Eskişehir region. Liquid phase catalytic oxidation of methyl orange azo dye has been carried out over Al-Fe/sepiolite catalysts using hydrogen peroxide as oxidant. The catalytic studies are performed in a glass reactor under atmospheric pressure by semi-batch operation. The effects of several parameters such as catalyst amount, metal loading, calcination temperature, pH, H2O2 concentration, reaction temperature and time on the methyl orange elimination have been examined. The elimination rate of 90.68% was achieved when studied with the catalyst with 8% active metal ratio (SepAlFe8) at pH 3.7 and 25°C. Kinetics studies show the degradation of methyl orange over the SepAlFe8 catalyst could be expressed by the pseudo-first-order reaction kinetics (k1 = 0.0049 min-1 at 25°C). The activation energy (Ea) of the reaction over this catalyst is foundas 29.48 kJ mol-1. It was also found that the catalytic oxidation process is endothermic (ΔH = 26.99 kJ mol-1) and nonspontaneous (ΔG = 96.72 kJ mol-1 at 25°C). The catalyst is chemically stable and reusable with low release of iron.

Synthesis, antioxidant, anticoagulant, and fibrinolytic activities of new isatin derivative

Background Isatin as a product was first obtained from the oxidation of indigo dye by nitric acid and chromic acids by Otto Linne Erdman and Auguste Laurent in 1841. Objective This study presents the synthesis of some new isatin derivatives and examines their biological activities. Materials and methods 2-Cyano-N’-(5-nitro-2-oxoindolin-3-ylidene)acetohydrazide (2) reacted with some reagents, namely, salicylaldehyde, phenyl isothiocyanate, ethyl chloroacetate, ethyl iodide, ethyl cyanoacetate, thioglycolic acid, phenyl isothiocyanate, malononitrile, and hydrazine hydrate to produce compounds 3, 4, 5, 6, 8, 9, 10, 11, and 12, respectively. Moreover, compound 6 reacted with hydrazine hydrate to produce compound 7. Antimicrobial activities of some newly synthesized compounds were studied. Results Antioxidant, anticoagulant, and fibrinolytic activities of the new synthesized compounds (1–12) were studied. Compound 10 exhibited highest fibrinolytic activity. On the contrary, compound 12 exhibited highest anticoagulant activities. Moreover, it was noticed that compound 9 exhibited highest antioxidant activity. Conclusion In summary, 14 novel isatin derivatives were synthesized and screened for their antioxidant, anticoagulant, and fibrinolytic activities. Some compounds displayed moderate-to-excellent activities such as antioxidant, anticoagulant, and fibrinolytic agents.

Antioxidant activity of polymeric biocide polyhexamethylene guanidine hydrochloride

Cationic polymer polyhexamethylene guanidine hydrochloride (PHMG-Cl) is promising biocide that combines a broad spectrum of antimicrobial activity, mod-erate toxicity, as well as reasonable cost. It is widely used as an effective disinfect-ant in cooling systems, swimming pools, and hospitals, personal hygiene products, etc. Recently PHMG-Cl was found to have pronounced anti-inflammatory and wound healing properties and therefore may be used for the treatment of chronic wounds and thermal burns. This may indicate the antioxidant activity of polymeric biocide. In this study, PHMG-Cl has been synthesized by melt polycondensation of guanidine hydrochloride and 1,6-hexamethylenediamine. The structure of the cati-onic polymer was confirmed by 1H NMR and IR spectroscopy. The viscosity-average molecular weight of PHMG-Cl was found to be 10700. The antioxidant activity of PHMG-Cl has been studied by using different methods. In the methylene blue (MB) dye test, the oxidation of MB by hydroxyl radicals generating in Fenton’s system was found to decrease in the presence of PHMG-Cl in a molar ratio to MB of 5:1 and 10:1 (by 26 % and 38 %, respectively). At the same time, complete dye oxidation was observed when guanidine hydrochloride was used instead of PHMG-Cl. The antioxidant activity of PHMG-Cl has also been studied in the model system of radical chain oxidation of benzyl alcohol (BA). In this system, alkyl and peroxyl radicals are formed. The antioxidant activity was determined by a decrease of the initial rate of oxygen absorption during the initiated oxidation of BA. The introduc-tion of PHMG-Cl into the oxidized system in the concentrations ranged from 1.3·10-3 - 1.6·10-2 mol/l decreased the oxidation rate of BA by 4.5–88 %. This result demonstrates that PHMG-Cl effectively inhibits radical chain oxidation of BA. However, further research is needed to elucidate the mechanism of free radical de-activation by a polymer biocide.

Green synthesized α-Fe2O3 mesoporous network for heterogeneous Fenton oxidation of thiazine dye

Green-synthesized mesoporous-structures have widespread attention due to its environmentally-benign nature and numerous applications. Herein, we report the green synthesis of mesoporous iron oxide network using green tea extract. The morphological and phase analyses were evaluated and elucidated the formation of mesoporous-structure showing predominantly hematite-phase. Catalytic role of α-Fe2O3 was investigated in Fenton reaction for the removal of methylene blue dye to understand its significance in wastewater treatment.

Application of central composite design for electrochemical oxidation of reactive dye on Ti/MWCNT electrode

In the present study, degradation of Reactive Orange 7 dye was investigated using a new designed titanium electrode, in which a plate of Ti was coated with multi-walled carbon nanotubes (Ti/MWCNT) via electrophoretic deposition technique. A series of characterizations including field scanning electron microscopy, X-ray diffraction, cyclic voltammetry, scanning electrochemical impedance spectroscopy and chronoamperometric analysis were performed to investigate MWCNT impact on the microstructure and electrochemical properties of Ti electrode. Furthermore, the effect of main operating parameters as independent variables (current density, electrolyte concentration, initial pH, and electrolysis time) on color removal efficiency as response variable were investigated and optimized by central composite design under response surface methodology. The maximum color removal efficiency of 89.1% and chemical oxygen demand removal efficiency of 55% were obtained, under the optimum condition. These results indicate that the presence of MWCNT on the Ti substrate noticeably promoted the electrochemical activity and the electrodes’ property for treatment of dye in aqueous solution.

Optimized synthesis of CA/EDTA modified cotton fiber Fe complex as a sustainable hybrid photocatalyst for accelerating simultaneous removal of Cr(VI) and azo dye

Tartaric acid (TA), citric acid (CA), or butanetetracarboxylic acid ((BTCA)) was mixed with Na2EDTA to modify cotton fiber. Fe3+ ions were then used to coordinate with the resulting modified cotton fiber to produce a novel hybrid photocatalyst for enhancing simultaneous removal of Cr(VI) and azo dye from water. High concentration of TA or CA improved the activity of photocatalyst for Cr(VI) reduction and dye oxidation. CA/EDTA modified cotton Fe complex showed a better Cr removal efficiency than the other two complexes. Cr removal efficiency was further improved when the same molar ratio of CA and Na2EDTA was used. Increasing Fe content of the photocatalyst significantly improved its catalytic performance, especially at the acidic condition. The highest Cr removal efficiency was obtained at Fe content of 0.049 mmol g−1. Moreover, Cr species and dye molecules could almost entirely be removed using 50.0 g L−1 of CA/EDTA modified cotton Fe complex.

New laser-based method for the synthesis of stable and active Ti/SnO2–Sb anodes

The main drawback impairing the application of highly electrocatalytic SnO2–Sb anodes in the removal of recalcitrant pollutants from wastewater is their short service life. Here, we report the synthesis of Ti/SnO2–Sb anodes with improved stability through a CO2 laser as the primary heating source. The influence of different calcination temperatures (400, 500, 600 °C), and varied composition of the solvent in the precursor solution, on the stability and activity of the anodes, were investigated. Notably, the use of the CO2 laser heating method at 600 °C improves the service life up to 5-fold as compared to the conventionally prepared anodes. The laser-made Ti/SnO2–Sb anode calcined at 600 °C exhibits the best electrocatalytic performance with the fastest color removal rates in the oxidation of methylene blue dye. Therefore, for the first time, Ti/SnO2–Sb anodes with superior properties were produced by a fast method employing CO2 laser, envisaging its future applications in wastewater treatment.

A nanobiosensor based on graphene oxide and DNA binding dye for multi-microRNAs detection.

Multiplex assays for detection of biomarkers, provide advantageous analyses of different factors related to diagnoses of diseases. The Alzheimer’s disease (AD) is one of the most common disease in old people in societies which is increasing, significantly. A group of microRNAs (miRNAs) play an important role in developing the disease which can be considered as early stage biomarkers. Since, selective, sensitive, simple and rapid method for detection of these miRNAs in a single test is critical for early diagnosis and efficient therapy of the disease, herein, we report a sensitive fluorescence assay based on enzyme-free and isothermal hybridization chain reaction with SYBR Green and graphene oxide (GOX) for early detection of miR-137 and miR-142, as two Alzheimer’s biomarkers. Fluorescence spectrophotometry based on SYBR Green signal and GOX as the fluorescence quencher was used for detection and quantification of targets’ miRNAs and change in fluorescence intensity due to absence and presence of the targets was measured. The limit of detection in the newly designed nanobiosensor was achieved as 82 pM with a sensitive detection of the miRNAs from 0.05 to 5 nM, that is critical for detecting the biomarkers. Given the real range of concentrations of miRNAs in blood (from nanomolar to femtomolar values), the method holds great promise in dual and multiple targets detection due to its sensitivity, rapidness, inexpensive and specificity which provides a convenient detection method of Alzheimer’s in early stage.

Photoelectrocatalytic performance improvement of BiVO4 thin film fabrication via effecting of calcination temperature strategy

The fabrication of bismuth vanadate (BiVO4) thin films on fluorine-doped tin oxide (FTO) were developed by cyclic voltammetry deposition. The effect of calcination temperature on BiVO4 thin film characteristics was studied to improve the photoelectrocatalytic water oxidation and organic dye degradation performance. A UV–visible spectrophotometer, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy were used to characterize the fabricated BiVO4 thin film on the FTO substrate. The photoelectrocatalytic properties of the FTO/BiVO4 electrode were investigated by studying the efficiency of water oxidation and rhodamine B degradation. The BiVO4 thin film shows high visible light absorption and high crystallinity monoclinic BiVO4 at a calcination temperature ranging from 400 to 500 °C. The calcination temperature at 500 °C exhibits the highest photoelectrocatalytic oxidation properties related to high porosity and lowest charge transfer resistance properties. The BiVO4 thin films annealed at 500 °C, which also shows the highest rhodamine B degradation performance up to 93% for 1 h. The research confirms that calcination temperature is a significant parameter to control BiVO4 thin film characteristics and photoelectrocatalytic properties. The fabricated BiVO4 thin film at the optimum condition can apply as a photoanode for other photoelectrocatalytic applications.

A simplistic approach for the synthesis of CuS-CdS heterostructure: A novel photo catalyst for oxidative dye degradation

Direct synthesis of CuS-CdS based mesoporous composite materials and their photocatalytic activity are delineated. In this study, a series of CuS micro flowers (mf) decorated with varying amounts of CdS nanoparticles (NP) have been synthesized successfully in a controlled manner. Relatively easy synthesis of material along with its surfactant-free clean surfaced heterojunction accentuates the reliability of the protocol described here. Full characterization of these semiconducting materials was accomplished with a series of analytical techniques, which include powder x-ray diffraction (PXRD), scanning electron microscopy (SEM), tunnelling electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), UV–vis, IR, BET and lifetime studies. Upon varying the concentration of precursor of Cd in the reactions, the resulting materials exhibited a well-demarcated change in morphologies ranging from undifferentiated mass to well-differentiated flower-like architectures. The thoroughly characterized composite was accessed finally for its potential photocatalytic activity for the degradation of organic dyes. The results showed 96.0% degradation of rhodamine B (RhB) over 10 min and 94.7% degradation of methylene blue (MB) over 9 min. This observed rate of degradation was much higher compared to that observed in the case of pure CuS (62.0% of RhB and 50.2% of MB).

Synergistic advance Fenton oxidation and hydrodynamic cavitation treatment of persistent organic dyes in textile wastewater

This is an investigation into the treatment of simulated Orange II sodium salt (OR2) contaminant in wastewater using jet-loop hydrodynamic cavitation in hybrid combination with hydrogen peroxide (H2O2) and nano zero valent iron (nZVI). A 69.8 % degradation of OR2 (10 mg/L) was achieved per hour in the jet-loop hydrodynamic cavitation system by itself (inlet pressure = 400 kPa, pH = 2, volume = 10 L). The combination of H2O2 and iron (II) sulfate in the jet loop hydrodynamic cavitation was not very effective. This is due to the possible scavenging effect of the iron (II) sulfate and H2O2 on the hydroxyl radical. However, the combinational treatment using an optimum amount of H2O2 and nZVI in the jet loop hydrodynamic cavitation resulted in 99 % decolouration of the OR2 solution within an hour treatment. 74 % mineralisation was also achieved as a function of % TOC reduction (400 kPa, pH 2, 1 mg/L H2O2, 1 mg/L nZVI, 1 h). The enhancement of the degradation with hydrogen peroxide, iron sulfate or nano zero valent iron led to the generation of nitrate ions and sulfate ion as evident by the UV spectrometer, TOC, FT-IR and GC–MS analysis. This result shows the synergistic enhancement in the mineralization of azo dye containing industrial wastewater during the combinational treatment with advanced Fenton oxidation (H2O2 and nZVI) in the jet loop hydrodynamic cavitation system.

Impact of housing nursery pigs according to body weight on the onset of feed intake, aggressive behavior, and growth performance.

Housing nursery pigs according to body weight is an observed common practice in production systems and, supposedly, improves growth performance and reduces body weight (BW) variation. This 42-day study evaluated the effects of housing nursery pigs according to BW on performance, onset of feed intake, and aggressive behavior. A total of 504 pigs were ranked by BW at weaning and categorized into three groups of 168 pigs each: light, medium, and heavy. Pigs were randomly distributed to unsorted pens (Unsorted) containing 6 pigs of each weight group and sorted pens with 18 pigs from just one group per pen (Sorted). From weaning to day 3, pigs were fed a diet containing 1% iron oxide dye and rectal swabs presenting red coloration were evaluated to assess feed intake onset. Eight pens were video recorded to evaluate aggressive behavior. Sorted-Heavy pigs delayed the onset of feed intake (P ≤ 0.011) and presented more aggressive behaviors than Sorted-Light and Sorted-Medium pigs (P ≤ 0.036). In Unsorted, onset of feed intake showed no differences between weight categories. Also, no differences were observed for aggressive behavior between Sorted and Unsorted. Final BW showed no differences between Sorted and Unsorted pigs. The within-pen weight coefficient variation (CV) was slightly different (P = 0.042) between Sorted and Unsorted pigs (13.3 and 15.6%, respectively), at the end of the study. Thus, sorting nursery pigs by BW did not improve growth performance and also, induce a lag of post-weaning feed intake onset and increased fights in Heavy pigs.

Synthesis of an environmental nano-polyoxometalate (α2P2W17CoO61)8− as catalyst for dyes degradation: A comparative study oxidation of indigoid and azo dyes

A nanopolyoxometalate (nano-POM) compound consisting of saturated Dawson anions (α2P2W17CoO61)8− has been synthesized and characterized by various analytical methods, UV–vis spectroscopy, FT-IR spectroscopy, single crystal X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray analysis (EDX).The separately oxidative degradation of indigo carmine and methyl orange dyes in aqueous solution by KMnO4 using (α2P2W17CoO61)8− as catalyst was investigated. The full Decolorization was attained during the first minutes of oxidation process by this new homogeneous system (dye/KMnO4/α2P2W17O61Co). The experimental results showed that the catalyst greatly affected the discoloration efficiency; it was up to 75.4 % and 66.1 % respectively for IC and MO under these optimum conditions: an initial potassium permanganate concentration of 0.02 mM, a catalyst concentration of 0.2 mM and initial concentration dyes of 5 mg/L at pH 3 and room temperature (25 °C).The effect of other Dawson type polyoxometalates on the dyes oxidation under the same conditions was evaluated. After four consecutive reaction cycles, the catalyst (α2P2W17CoO61)8− exhibited a good recyclability and reusability without significant loss of activity. The precedents analytical methods indicated that this recovered catalyst has effectively a good stability. This nano-POM function as a recyclable efficient catalyst for the rapid removal of various anionic textile dyes from aqueous solutions.

Morphology-controlled electrochemical sensing of erbium- benzenetricarboxylic acid frameworks for azo dyes and flavonoids

Generally, materials with different morphologies are expected to have different electrochemical properties. Here, three kinds of erbium-based metal-organic frameworks with different morphologies were prepared using erbium nitrate and 1,3,5-benzenetricarboxylic acid (H3BTC) as the source in N, N-dimethylformamide (DMF) by adding various amounts of ammonium acetate (CH3COONH4). The characterization of X-ray diffraction, infrared spectroscopy and X-ray photoelectron spectroscopy proved that the obtained materials were Er-BTC. Scanning electron microscope measurements indicated that the amount of CH3COONH4 had obvious effects on the morphology. More importantly, the active sensing area and interface electron transfer ability of Er-BTC were controlled by the morphology, which revealed by rotating ring disk electrode and electrochemical impedance spectroscopy. Moreover, the prepared Er-BTC with different morphologies exhibited different signal enhancement ability toward the oxidation of azo dyes (allura red and rhodamine B) and flavonoids (quercetin and luteolin). Based on the morphology-controlled sensing of Er-BTC, a highly sensitive detection platform were developed for allura red/rhodamine B and quercetin/luteolin, with detection limits of 0.30/0.56 nM and 0.22/0.14 nM. Besides, this new method was successfully used in drink and tea samples, and the results were in good agreement with those obtained from high-performance liquid chromatography.

Activated carbon as carrier in fluidized bed reactor for Fenton oxidation of recalcitrant dye: Oxidation-adsorption synergy and surface interaction

In this work, we investigated the synergy of oxidation-adsorption and surface interaction in fluidized bed Fenton process with granular activated carbon (GAC) as carriers. Experiments were conducted to evaluate the synergy of oxidation and adsorption in the removal of a model pollutant, Reactive Black 5. The effects of carrier loading and solution pH on the process performance were investigated. To determine the nature of interaction between the carriers, Fenton’s reagent and pollutant, the surface of the GAC was analyzed using FTIR, SEM/EDX, XPS and BET analyses. The highest COD and color removal obtained were 83% and 99% respectively, at 20 g carrier loading and pH 3. More than 28% of the initial COD was removed through adsorption by the carrier. The process performance increased with increase in carrier loading but decreased when the loading exceeded a certain threshold. Although the highest COD removal was obtained at pH 3, effective removal was still achieved at pH 7. The surface analysis of the carrier reveals that both Fenton’s reagent and organic pollutant are adsorbed on the surface of the carrier, indicating that the removal of the pollutant is through both adsorption and oxidation. The performance of GAC in this study is superior to the commonly employed carrier, SiO2. This study shows that GAC can be used as an effective carrier in fluidized bed for Fenton process.

Degradation of simulated Direct Orange-S (DO-S) textile effluent using nonthermal atmospheric pressure plasma jet.

One of the major environmental issues of textile industries is the discharge of large quantities of textile effluents, which are source of contamination of water bodies on surface of earth and quality of groundwater. The effluents are toxic, non-biodegradable, carcinogenic and prodigious threats to human and aquatic creatures. Since textile effluents can be treated efficiently and effectively by various advanced oxidation processes (AOPs). Among the various AOPs, cold atmospheric pressure plasma is a promising method among many prominent techniques available to treat the effluents. In this paper, we report about the degradation of simulated effluent, namely Direct Orange-S (DO-S) aqueous solution, using nonthermal atmospheric pressure plasma jet. The plasma treatment of DO-S aqueous solution was carried out as a function of various operating parameters such as potential and treatment time. The change in properties of treated DO-S dye was investigated by means of various analytical techniques such as high-performance liquid chromatography, UV-visible(UV-Vis) spectroscopy and determination of total organic content (TOC). The reactive species present in the samples were identified using optical emission spectrometry (OES). OES results confirmed that the formation of reactive oxygen and nitrogen species during the plasma treatment in the liquid surface was responsible for dye oxidation and degradation. Degradation efficiency, as monitored by color removal efficiency, of 96% could be achieved after 1h of treatment. Concurrently, the TOC values were found to decrease with plasma treatment, implying that the plasma treatment process enhanced the non-toxicity nature of DO-S aqueous solution. Toxicity of the untreated and plasma-treated dye solution samples was studied using Escherichia coli (E. coli) and Staphylococcus (S. aureus) organisms, which demonstrated that the plasma-treated dye solution was non-toxic in nature compared with untreated one.

Homogeneous and heterogeneous catalytic oxidation of some azo dyes using copper(II) ions.

The kinetics of the homogeneous and heterogeneous catalytic oxidation processes of three azo dyes in presence of copper (II) - ions, copper (II) - ions - supported on alumina and on zinc oxide as well as copper ammonia complex supported on alumina were investigated in aqueous solutions. The dyes are Chromotrope 2B (C2B), Chromotrope 2R (C2R) and Chrysophenen (CRY). The reaction progress was followed by monitoring the decrease in absorbance at ℷmax 512, 511 and 401 nm, respectively. The rate of reaction increased with increasing either the concentration of the dye or the catalyst, giving a plateau at high concentrations of the catalyst. On the other hand, the rate of reaction increased gradually with increasing hydrogen peroxide concentration attaining a maximum then decreased thereafter. The reaction rate was also increased with increasing pH and temperature and was found to be entropy controlled. This work could be applied for dye baths water reuse to reduce costs in textile and dyeing factories as will as for environmental purposes.