Decolourization Of Methyl Orange Research Articles

Effect of pH, Salinity, Dye, and Biomass Concentration on Decolourization of Azo Dye Methyl Orange in Denitrifying Conditions

A recent study by the current authors found simultaneous decolourization and mineralization of high concentrations of methyl orange (500 mg/L) in an anoxic up-flow reactor in denitrifying conditions. To supplement this work, various batch reactor studies were carried out to study the effect of (i) pH (4 to 9), (ii) salinity (1 g/L NaCl to 10 g/L NaCl), (iii) dye concentration (100 mg/L to 1000 mg/L), (iv) biomass concentration (0.3 g/L to 0.21 g/L); on the process, and (iv) kinetics of decolourization in denitrifying conditions. The adapted mixed microbial consortium, originally sourced from the activated sludge process, was capable to simultaneously remove colour, COD, and NO3−-N under denitrifying conditions, even at high methyl orange (MO) concentrations of 1000 mg/L at 84 h. Although the decolourization was possible for wide ranges of pH, better performance was obtained at alkaline pH levels. The decolourization performance increased when biomass concentration increased and was not affected by salinity up to 10 g/L NaCl. This may have been due to enhanced lyses of biomass at high salt concentrations. Batch kinetic studies showed that the MO decolourization followed first-order kinetics, with a rate constant of 0.0612 h−1. Results of this study may help in the future application of textile effluent treatments, using a high biomass retention reactor in denitrifying conditions with minimum sludge disposal costs.

Methyl orange decolourization through hydrodynamic cavitation in high salinity solutions

This paper presents the experimental results obtained on the decolourization of methyl orange (MO) in saline solutions, carried out through hydrodynamic cavitation (HC), used as a stand-alone technique, and in a hybrid configuration coupling with hydrogen peroxide. Experiments were carried out by adding NaCl in a solution in the range of 1.5 to 5 g/L to study the effect of salt on dye degradation by simulating the composition of a real tannery liquid waste. The results showed that the maximum efficiency was about 30% using a Venturi tube at an operating pressure of 0.55 MPa. The presence of hydrogen peroxide allowed the degradation process to be slightly below 70%; the presence of sodium chloride (5.0 mg/L) increased the decolourization efficiency up to about 70% as well, while the combined presence of NaCl and H2O2 had a negative outcome. The experiments on synthetic waste allowed to gain a MO degradation slightly below 90%. Process analysis was carried out to evaluate the possible integration of the HC within a real wastewater treatment plant by comparing the traditional treatment train with a new plant configuration, in which HC takes the place of a conventional coagulation tank.

Efficient and synergistic decolourization and nitrate removal using a single-chamber with a coupled biocathode-photoanode system

With the continuous development of the chemical industries, synergistic removal of carbon and nitrogen contaminants has drawn much attention. In this work, a novel strategy for the synergistic removal of methyl orange (MO) and nitrate was developed in a single reactor by combining a TiO2/g-C3N4 nanosheet/graphene photoanode and denitrifying biofilm cathode. Under xenon light illumination, the photocatalytic MO decolorization rate exceeded 90% (the initial concentration of MO was as high as 100 mg·L−1) with a biocathode potential bias of −0.5 V vs Ag/AgCl; additionally, the decolourization rate apparently followed first-order kinetics with a constant of 0.11 ± 0.02 h−1. The improved MO decolourization rate was mainly because the biocathode effectively enhanced the charge separation of the photogenerated charge at the TiO2/g-C3N4 nanosheet/graphene photoanode interface. In the meantime, the effluent nitrate was lower than 1 mg·N·L−1 at a biocathode potential of −0.5 V vs Ag/AgCl. The results indicated that the coupled biocathode-photoanode system could serve the purpose of simultaneously degrading MO and accomplishing nitrate reduction. Considering the sustainability of sunlight and the use of a biocathode, the coupled biocathode-photoanode system is a promising alternative for the simultaneous removal of biorefractory organics and nitrate.

The decolourisation of Methyl Orange and textile effluent under UV using commercial and synthesized nano-TiO2

The efficiency of the nanophotocatalysts was determined in a laboratory prepared solutions of model dye compound methyl orange (MO), which is a dyestuff typically applied on textiles. The reduction in the concentration of the dye over time was measured by using UV-VIS spectrophotometry. The decolourisation of MO solutions was characterized at the onset and after exposure to 9W germicidal UV lamps at various time intervals, viz. 30, 60, 120, 180, 300 and 420 minutes. The color transformation from dark-orange, (MO) to a transparent clear solution or a slightly colored solution is an indication of the decomposition of the organic dye contaminants into lower molecular weight organics and innocuous CO2 and water. The results show that the commercial nano-TiO2 is more efficient in decolourising the model dye and the textile effluents.

Decolourization of Methyl Orange (MO) by electrocoagulation (EC) using iron electrodes under a magnetic field (MF)

Decolourization of Methyl Orange (MO) by electrocoagulation (EC) using iron electrodes under a magnetic field (MF)

Process and kinetics of azo dye decolourization in bioelectrochemical systems: effect of several key factors.

This study explored the influence of several key factors on the process and kinetics of azo dye decolourization in bioelectrochemical systems (BESs), including cathode potential, dissolved oxygen (DO) concentration of catholyte and biofilm formed on the cathode. The results show that azo dye methyl orange (MO) decolourization in the BES could be well described with the pseudo first-order kinetics. The MO decolourization efficiency increased from 0 to 94.90 ± 0.01% and correspondingly the reaction rate constant increased from 0 to 0.503 ± 0.001 h−1 with the decrease in cathodic electrode potential from −0.2 to −0.8 V vs Ag/AgCl. On the contrary, DO concentration of the catholyte had a negative impact on MO decolourization in the BES. When DO concentration increased from zero to 5.80 mg L−1, the MO decolourization efficiency decreased from 87.19 ± 4.73% to 27.77 ± 0.06% and correspondingly the reaction rate constant reduced from 0.207 ± 0.042 to 0.033 ± 0.007 h−1. Additionally, the results suggest that the biofilm formed on the cathode could led to an adverse rather than a positive effect on azo dye decolourization in the BES in terms of efficiency and kinetics.

Study of the preparation of CdS on the surface of geopolymer spheres and photocatalyst performance

Geopolymer spheres (GS) made of chemosynthetic geopolymers are prepared through a suspension solidification method. Cd2+ ions can easily absorb on the surface of the GS via van der Waals forces and ion exchange interactions. A photochemical growth method is used to grow CdS crystal particles homogeneously on the GS surface. The CdS-GS exhibited good adsorption and photocatalytic degradation performance in the decolourisation of methyl orange (MO) with a degradation efficiency of approximately 92.57%. The analysis of the CdS-GS degradation kinetics of MO indicated that it is corresponding to the pseudo-second-order rate equation. The repeating degradation experimental results indicated the CdS-GS photocatalyst had relatively stable photocatalytic performance.

수중 유기물처리를 위한 광펜톤반응의 최적조건 도출

Fenton is the reaction using the OH· radicals generating by interaction between hydrogen peroxide and Fe 2+ which can oxidize the contaminants. Fe 2+ ions are oxidized to Fe 3+ ions by reaction with H2O2 and formed OH· radicals. UV-Fenton process includes the additional reaction that generates the OH· radicals by photodegradation of H2O2. In methylorange (MO) decolourization experiment with UV-Fenton, optimal Fe 2+ :H 2O2 ratio was obtained at 1 : 10. Based on the obtained condition (H2O2 =1 0 mM, Fe 2+ = 1 mM) with/without UV-fenton experiment was carried out. Removal efficiency and sludge production were measured at 30 min. The case of w/o UV irradiation and only H2O2 was hardly treated and only Fe 2+ showed 65% removal owing to coagulation. When UV-Fenton process in optimal ratio (Fe 2+ :H 2O2 = 1 : 10), UV irradiation showed better removal efficiency than of w/o UV irradiation. Also, MO decolourization was a function of the hydrogen peroxide concentration (x1), Fe 2+ :H2O2 ratio (x2), and numbers of UV lamp (x3) from the application of the response surface methodology. Statistical results showed the order of significance of the independent variables to be hydrogen peroxide concentration > numbers of UV l amp > Fe 2+ :H 2O2 ratio.

Synthesis, Characterization and Visible Light Induced Photocatalytic Activity of Metal Doped TiO2

The photo catalytic decolourization of Methyl orange (MO) widely used as a textile dye, can be photocatalysed by TiO2 based photo catalysts using Advanced Oxidation Process (AOPs). Doped TiO2 photo catalysts were synthesized by liquid impregnation method and sol-gel method and characterized by UV-Visible spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). TiO2 appears to be a suitable catalyst for water treatment. In this study the experiments were carried out by irradiating the aqueous solution of dyes containing photo catalyst under solar light. The rate of decolourizaion was estimated from residual concentrations using photocolourimeter. Photodecolourization efficiency was zero when the photo catalysis was carried out in the absence of sunlight and it was small in presence of sunlight without catalyst. It was found that about 86% decolourization occurs with photo catalyst in the presence of sunlight within 6hr. After 8hr sunlight irradiation, complete decolourization was observed for metal doped photo catalysts. The effect of parameters such as amount of photo catalyst, irradiation time and dye concentration were also examined.

The effect of surfactant on dye removal by polyelectrolyte enhanced ultrafiltration

AbstractPolyelectrolyte-based separation of toxic dyes is studied to estimate the potential of polyelectrolyte enhanced ultrafiltration (PEUF) using polyethylene glycol (PEG). Removal of methyl orange (MO) an azo dye from aqueous solutions, by continuous polymer enhanced ultrafiltration (PEUF) was investigated. The permeate flux profile and obtained retention of MO were studied as a function of polyelectrolyte concentrations, transmembrane pressure, ionic strength and pH in the absence and in the presence of surfactant (CTAB). The experiments showed that retention of MO in the presence of PEG of different concentrations was 65%. This may be due to that the PEG polyelectrolyte cannot bind MO to form aggregates to enhance UF process. However, when the CTAB was applied at a fixed concentration below CMC, MO decolourization increased and reached a limiting value of 99%. The high rejection for MO dye is due to the formation of H aggregates in the aqueous solution. This result was confirmed by the change of the...

Solar, visible and UV light photocatalytic activity of CoWO4for the decolourization of methyl orange

AbstractThe photocatalyst CoWO4 was synthesized by co-precipitation method with slight modification and well characterized by FT-IR, UV–vis diffuse reflectance spectra, X-ray diffraction, AFM and field emission scanning electron microscope techniques. The elemental composition present in the photocatalyst was confirmed by recording EDX spectrum. The photocatalytic activity of CoWO4 for the decolourization of methyl orange (MO) was investigated under solar, visible and Ultra-Violet (UV) light irradiation. The remarkable photocatalytic decolourization of MO was achieved under solar and visible light irradiation than that of TiO2. The high surface area of 55.0527 m²/g enhances the adsorption of anionic dye MO on the surface of the positively charged catalyst at pH 3 thus increases the photocatalytic activity. Under UV light irradiation, photocatalytic activity increases which may be due to high energy of photons. The essential parameters such as amount of catalyst, dye concentration and initial pH influence ...

Enzymatic decolourisation of Methyl Orange and Bismarck Brown using crude peroxidase from Armoracia rusticana

The decolourisation of Methyl Orange (MO) and Bismarck Brown (BB) by crude peroxidase from Armoracia rusticana (Horseradish) was studied by varying different reaction parameters. The pH of the reaction mixture, initial dye concentration, amount of enzyme and hydrogen peroxide concentration were optimised for ambient temperatures (30 ± 2 °C). The optimum pH for decolourisation was 4.0 (72.95 %) and 3.0 (79.24 %) for MO and BB, respectively. Also it was found that the Chemical Oxygen Demand of the enzyme-treated sample was significantly lower than that of the untreated controls for both dyes. The addition of a complex iron salt like Ferric EDTA was found to enhance the decolourisation of both dyes at pH 6.0, showing an increase of 8.69 % and 14.17 % in the decolourisation of MO and of BB, respectively. The present study explores the potential of crude peroxidase from horseradish to decolourise representative monoazo and diazo dyes, MO and BB, respectively. An attempt has been made to utilise a crude enzyme with appreciable activity obtained after minimal processing for the decolourisation of the aforesaid dyes. The findings of this study would find application in the enzymatic treatment of wastewater containing azo dyes.

Immobilisation of CdS nanoparticles on chitosan microspheres via a photochemical method with enhanced photocatalytic activity in the decolourisation of methyl orange

In this study, CdS nanoparticles were directly grown on the surfaces of chitosan microspheres (CM) via photochemical method with irradiation from an 8W ultraviolet (UV) lamp. The nanoparticles exhibited an almost spherical shape, were closely arranged, and were immobilised on the microspheres because of the induction of the amino and hydroxyl groups of the chitosan. The CM-immobilised CdS nanoparticles showed higher activity and easier recyclability than pure CdS particles obtained in the same conditions when used in the decolourisation of methyl orange (MO) under UV–vis light. The experiments proved that the photodegradation of MO was mainly caused by the oxidisation of superoxide radicals (O2−) generated by the reaction between the electrons and the adsorbed O2. The functional groups of CM may prevent the recombination of electron/holes and effectively promote photocatalytic reactions. This photochemical method is new, general, and promising for the immobilisation of catalyst particles on polymer microspheres, which results in enhanced activity.

Heterologous expression and characterization of laccase 2 from Coprinopsis cinerea capable of decolourizing different recalcitrant dyes

The gene (CcLcc2) encoding laccase from the basidiomycete Coprinopsis cinerea Okayama-7 #130 was synthesized by polymerase chain reaction-based two-step DNA synthesis, and heterologously expressed in Pichia pastoris. The recombinant protein was purified by ammonium sulphate precipitation and nickel nitrilotriacetic acid chromatography. The molecular mass of CcLcc2 was estimated to be 54 kDa by denaturing polyacrylamide gel electrophoresis. The optimum pH and temperature for laccase catalysis for the oxidation of 2,2ʹ-azino-bis(3-ethylbenzothiazoline-6-sulphonate) (ABTS) were 2.6 and 45 °C, respectively. The Km values of the enzyme towards the substrates ABTS, 2,6-dimethoxyphenol (2,6-DMP) and guaiacol were 0.93, 1.02 and 28.07 mmol·L−1, respectively. The decolourization of methyl orange, crystal violet and malachite green, commonly used in the textile industry, was assessed. The decolourization percentage of crystal violet and malachite green was 80% after 4 h of reaction, and that of methyl orange was 50% at 4 h. These results show that the CcLcc2 has enormous potential for the decolourization of highly stable triphenylmethane dyes.

Plasma-chemical and photo-catalytic degradation of methyl orange

Non-thermal atmospheric humid air plasma is used to investigate chemical reactions mechanisms of predominantly produced neutral hydroxyl radicals by gliding arc discharges with Methyl Orange (MO). UV/Visible spectroscopy and electrochemical measurements were performed. Treated solutions show that highly reactive HOradicals interaction favours the creation of intermediate species followed by their degradation leading to one aromatic ring end product. Photocatalytic (UV/TiO2 and UV/H2O2) treatments lead to the complete decolourisation of MO within few minutes. The results obtained may confirm that the final product of air plasma MO interaction contains NO2 and NH2 groups, the consequence ofNO presence in plasma.

Preparation of Pd-containing TiO2 film and its photocatalytic properties

The palladium-containing titanium dioxide films on glass substrate were prepared in a dip-coating process using a palladium-containing TiO2 sol. Following calcinations at 300°C, the authors rated the resulting film as having a hardness of 5 H as determined by a pencil scratch hardness tester. The photocatalytic activities were evaluated by decolourisation of methyl orange and degradation of NOx, respectively. Simple analysis was carried out using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence spectroscopy (PL) to observe changes in the film following palladium modification. Modification of TiO2 films with palladium enhanced the photocatalytic activity for decolourisation of dye and oxidation of NO.

Decolourisation of dye solution using an electrical discharge with TiO<SUB align=right>2 suspension

An electrical discharge in water with TiO2 suspension has been applied for the decolourisation of methyl orange as a model of dye. The results showed the decolourisation was successful in the reactor. The increase in the flow rate of gas injection enhanced the decolourisation rate. Oxygen injection had a stronger influence when compared with Ar injection. The suspension of TiO2 improved the decolourisation. The results suggested the plasma-assisted three-phase reactor had a promising possibility to treat various kinds of wastewater.

Kinetic–spectrophotometric determination of ascorbic acid by inhibition of the hydrochloric acid–bromate reaction

A new analytical method was developed for the determination of ascorbic acid in fruit juice and pharmaceuticals. The method is based on its inhibition effect on the reaction between hydrochloric acid and bromate. The decolourisation of Methyl Orange by the reaction products was used to monitor the reaction spectrophotometrically at 510 nm. The linearity range of the calibration graph depends on bromate concentration. The variable affecting the rate of the reaction was investigated. The method is simple, rapid, relatively sensitive and precise. The limit of detection is 7.6×10 −6 M and calibration rang is 8×10 −6–1.2×10 −3 M ascorbic acid. The relative standard deviation of seven replication determinations of 8×10 −6 and 2×10 −5 M ascorbic acid was 2.8 and 1.7%, respectively. The influence of potential interfering substance was studied. The method was successfully applied for the determination of ascorbic acid in pharmaceuticals.

Kinetic–spectophotometric determination of hydrazine by the inhibition of the bromate–hydrochloric acid reaction

A simple, sensitive, accurate and selective method for rapid determination of hydrazine is described which is based on its inhibition effect on the reaction between bromate and hydrochloric acid. The decolourisation of methyl orange by the reaction products was used to monitor the reaction spectrophotometrically at 525 nm. The method allows the determination of hydrazine in the range 3.0×10 −7–3.2×10 −5 M. The relative standard deviation for 10 determinations of 6.25×10 −6 M hydrazine is 1.2% and the detection limit of the method is 8.5×10 −8 M. The method is applied to the determination of hydrazine present in water.

Spectrophotometric determination of trace amounts of selenium with catalytic reduction of bromate by hydrazine in hydrochloric acid media

A method is presented for the determination of selenium, based on the catalytic effect of selenium(IV) on the reduction reaction of BrO − 3 by N 2H 4·2HCl. The decolourization of Methyl Orange by the reaction products was used to monitor the reaction spectrophotometrically at 525 nm. This method is precise, highly sensitive, simple, rapid, widely applicable and selective for the determination of selenium(IV) and total selenium. The variables which affected the reaction rate were fully investigated and the optimum conditions were established. Selenium, as low as 1 ng/ml, can be determined by this method. The relative standard deviation of 20 ng of selenium was 0.94% ( N = 10). The method was applied to the determination of Se(IV) in a health-care product.