Decolorization Rate Of Methyl Orange Research Articles

Treatment of Methyl Orange by Photocatalysis Floating Bed

A novel photocatalysis floating bed reactor was prepared to study for the degradation of textile wastewater. The reactor was assembled by short quartz tube loaded TiO 2 film, showing a good catalytic activity. The decolorization rate of methyl orange can reach 98.7% by the photocatalysis floating bed reactor under UV light irradiation for 8 hours. Scanning electron microscopy and EDS were used to characterize the structure of the photocatalyst. The results indicate that the TiO 2 films of 1 μm were loaded on short quartz tube in the photocatalysis floating bed reactor.

Evaluation of manganese peroxidase (MnP) for its ability to resist the ozonization and thereafter decolorize methyl orange

The goal of this study was to determine whether ozone can be used to suppress bacterial growth in operating a white rot fungi reactor system. The effects of ozone dose on the activity of manganese peroxidase (MnP) and on the death rate of Escherichia coli were investigated. The results showed that at ozone dose of 0.98 mg/L the MnP activity was not affected after 40 min continuous treatment while the Escherichia coli inactivation rate can reach 99.9% after 30 min; In addition, the MnP that exposed to ozone dose of 1.56 mg/L for 40 min maintained their activity for decolorization of Methyl Orange. After 16 h, the decolorization rate of Methyl Orange was about 41%. These results showed that MnP have the ability to resist to some extent the attack of ozonization, which suggest that ozone might have its potential in suppressing the bacteria contamination in operating the white rot fungi reactor.

Enhanced reductive degradation of methyl orange in a microbial fuel cell through cathode modification with redox mediators

A model azo dye, methyl orange (MO), was reduced through in situ utilization of the electrons derived from the anaerobic conversion of organics in a microbial fuel cell (MFC). The MO reduction process could be described by a pseudo first-order kinetic model with a rate constant of 1.29 day(-1). Electrochemical impedance spectroscopic analysis shows that the cathode had a high polarization resistance, which could decrease the reaction rate and limit the electron transfer. To improve the MO reduction efficiency, the cathode was modified with redox mediators to enhance the electron transfer. After modification with thionine, the polarization resistance significantly decreased by over 50%. As a consequence, the MO decolorization rate increased by over 20%, and the power density was enhanced by over three times. Compared with thionine, anthraquinone-2, 6-disulfonate modified cathode has less positive effect on the MFC performance. These results indicate that the electrode modification with thionine is a useful approach to accelerate the electrochemical reactions. This work provides useful information about the key factors limiting the azo dye reduction in the MFC and how to improve such a process.

Photocatalytic activity of nanocrystalline mesoporous-assembled TiO 2 photocatalyst for degradation of methyl orange monoazo dye in aqueous wastewater

In this work, nanocrystalline mesoporous-assembled TiO 2 photocatalyst was synthesized by a sol–gel process with the aid of a structure-directing surfactant and employed for the photocatalytic degradation of methyl orange azo dye (monoazo dye), as compared to various commercially available non-mesoporous-assembled TiO 2 powders. The experimental results showed that the synthesized mesoporous-assembled TiO 2 nanocrystal calcined at 500 °C provided superior decolorization and degradation performance to the non-mesoporous-assembled commercial TiO 2 powders. In addition, several operational parameters affecting the decolorization and degradation of methyl orange, namely photocatalyst dosage, initial dye concentration, H 2O 2 concentration, and initial solution pH, were systematically investigated, using the mesoporous-assembled TiO 2 nanocrystal. The optimum conditions were a photocatalyst dosage of 7 g/l, an initial dye concentration of 5 mg/l, a H 2O 2 concentration of 0.5 M, and an initial solution pH of 4.7, exhibiting the highest decolorization rate of methyl orange.

Degradation of methyl orange using short-wavelength UV irradiation with oxygen microbubbles

A novel wastewater treatment technique using 8 W low-pressure mercury lamps in the presence of uniform-sized microbubbles (diameter = 5.79 μm) was investigated for the decomposition of methyl orange as a model compound in aqueous solution. Photodegradation experiments were conducted with a BLB black light blue lamp (365 nm), a UV-C germicidal lamp (254 nm) and an ozone lamp (185 nm + 254 nm) both with and without oxygen microbubbles. The results show that the oxygen microbubbles accelerated the decolorization rate of methyl orange under 185 + 254 nm irradiation. In contrast, the microbubbles under 365 and 254 nm irradiation were unaffected on the decolorization of methyl orange. It was found that the pseudo-zero order decolorization reaction constant in microbubble system is 2.1 times higher than that in conventional large bubble system. Total organic carbon (TOC) reduction rate of methyl orange was greatly enhanced by oxygen microbubble under 185 + 254 nm irradiation, however, TOC reduction rate by nitrogen microbubble was much slower than that with 185 + 254 nm irradiation only. Possible reaction mechanisms for the decolorization and mineralization of methyl orange both with oxygen and nitrogen mirobubbles were proposed in this study.

A sensitive spectrophotometric method for determination of carbon tetrachloride with the aid of ultrasonic decolorization of methyl orange

A sensitive method for carbon tetrachloride (CCl 4) determination has been developed with the aid of ultrasonic oxidation decolorization of methyl orange (MO). It is found that the ultrasonic oxidation decolorization rate of MO can be significantly promoted by adding a little amount of CCl 4. The increased ultrasonic decolorization rate of MO is strongly dependent on the concentration of CCl 4 added, and a linear correlation is observed between the amount of CCl 4 and the decolorization rate of MO in the ultrasonic oxidation process. Thus, the CCl 4 determination is transformed to a simple and direct determination of the decoloration extent of MO solution at a given concentration. As an indirect spectrophotometric determination of CCl 4, the new method is sensitive and easy of operation with a maximum wavelength of 508 nm, molar absorptivity of 3.83 × 10 4 L mol −1 cm −1, and a Sandell sensitivity of 7.96 × 10 −3 μg cm −2. Under optimized conditions, Beer's law is obeyed in the range of 0.4–20 mg L −1 of CCl 4 (DL = 0.19 mg L −1, r = 0.9996). The concentrations of CCl 4 in several practical samples have been determined satisfactorily by using this method.

Effects of surface modification of TiO 2 with ascorbic acid on photocatalytic decolorization of an azo dye reactions and mechanisms

The formation of surface modification on TiO 2, which can be easily attained by a simple addition of ascorbic acid to aqueous TiO 2 suspensions, uniquely affects both photocatalytic reactions and mechanisms. Surface modification results in the formation of a colored surface complex that causes red shift of the absorption threshold of TiO 2, enhancing utilization of the solar spectrum. The decolorization rate of methyl orange, taken as a model for recalcitrant azo-dye, was observed to be the function of surface modified TiO 2 used during the process. It was found that surface modified TiO 2 was more effective for oxidation of azo bond than pure TiO 2 irradiated by both UV light and solar light. Through investigating the effects of dissolved oxygen, CCl 4 and tert-butyl alcohol on the decolorization of methyl orange, the mechanisms are proposed that the superoxides ( O 2 −) mediated oxidation pathways are dominant for cleavage of azo bond of methyl orange on surface modified TiO 2 with ascorbic acid, whereas the OH radical mediated oxidation pathways are largely inhibited due to the hindered complexation of ascorbic acid on the surface of TiO 2. Finally, elementary charge transfer process on surface modified TiO 2 and the implication to photocatalytic reaction pathway are discussed.

Effects of factors and interacted factors on the optimal decolorization process of methyl orange by ozone

The decolorization of methyl orange by ozone is effectively carried out in this study. Factors affecting the decolorization rate of methyl orange are investigated by a 2 5−1 fractional factorial design method. The influences of the main factor and two-factor interaction effects of the operating variables of pH, reaction temperature, agitation rate and concentrations of methyl orange and ozone stream on decolorization are established. The results show that the effect of concentration of ozone stream is the most important among the five main factor effects. Interaction between temperature and ozone stream concentration is the most significant effect among the ten two-factor interaction effects. A quadratic form fit using a modified central composite experimental design is obtained, and it is proved to be adequate for this system according to the multiple correlation coefficient and variance analysis.

Flow system based on sequential delivery of air-sandwiched solutions into a micro cell for spectrophotometric catalytic analysis

An air-sandwiched sample, reagent solutions and water with a total volume of 317 υ 1 are sequentially delivered by air carrier through PTFE tubing of 1 mm i.d. into a micro cell, where the solutions are mixed to start reaction, and the absorbance is measured against reaction time. This flow system was compared with the stopped-flow/flow-injection and manual batch techniques with regard to the determination of 20–500 ng of sulphide by measuring the decolorization rate of Methyl Orange with bromate. In the proposed flow system, a micro sample is diluted only with limited small volumes of reagent solutions and free from the additional dilution due to dispersion of the reacting solution. Therefore, the absolute sensitivity was ten times that of the manual batch technique using a millilitre-level sample and three times that of the stopped-flow/flow-injection technique.