Rate Of Decolourization Research Articles

Effect of pH and nutrient starvation on biodegradation of azo dyes by Pseudomonas sp

The effect of pH and some nutrients starvation on biodegradation of azo dyes (Orange II and Direct Blue 71) by Pseudomonas sp. was investigated. Highest percentage decolourization values of 56.50% and 45.20% were obtained at pH 7.0 and 6.5 for Orange II and Direct Blue 71 respectively. Rate of decolourization decreased with increasing concentration of nitrate (sodium nitrate) or sulphate (magnesium sulphate heptahydrate). Highest percentage decolourization (79.29% for Orange II and 72.38% for Direct Blue 71) was obtained in positive controls (no nitrate added). Corresponding values for sulphate-limited conditions were 76.50% for Orange II and 78.24% for Direct Blue 71 in positive controls (no sulphate added). The nitrogen of the generated aromatic amines provided the sole source of nitrogen in positive controls. Desulphonation of the aromatic moiety provided the sole source of sulphur in the positive control medium. The study shows that detoxification of ecosystems contaminated with azo dyes are enhanced under nitrate and sulphate-limited conditions. Journal of Applied Sciences and Environmental Management Vol. 9(1) 2005: 39-43

Simple and easy method for the determination of fungal growth and decolourative capacity in solid media

A technique was developed for studying the biodegradative ability of white rot fungi in different solid media. This technique enables the gravimetric determination of fungal growth (increase of biomass) and the spectrometric measurement of fungal decolourization ability (both by the determination of the production of the extracellular enzyme manganese-dependent peroxidase (MnP) and by the rate of decolourization of dyes). Bjerkandera sp., strain BOS55, was grown in different solid media. Its growth rate, decolourization of solophenil blue 2BL (azoic dye), neutral red (eurhodin dye), methyl green and crystal violet (triphenylmethane dyes) and the production of MnP were determined. Application of this technique enabled a spectrometric quantification of enzymatic activity. Assays indicate that greater amounts of MnP were present in agar plate cultures of Bjerkandera sp. than in liquid cultures.

UV-Induced Decolourization of an Azo Dye by Homogeneous Advanced Oxidation Processes

The decolourization of the azo dye Acid Black 24 was investigated using a homogeneous advanced oxidation process which comprised irradiating aqueous solutions of the dye with UV light at a wavelength of 254nm in the presence of either hydrogen peroxide, sodium persulphate or sodium periodate at a pH of 6.3. In all three cases, increasing the concentration of oxidant resulted in an enhancement in the rate of dye decolourization. Firstorder kinetics adequately described the disappearance of the dye. Reaction rate orders with respect to the oxidant species were 0.23, 1.17 and 0.90 for, respectively, peroxide, persulphate and periodate. The extent of dye mineralization was monitored by TOC measurements which showed that the use of periodate resulted in a lower final TOC than was obtained with either peroxide or persulphate.

Untersuchungen zur Reaktion von Pyrazolonazomethin‐Farbstoffen mit 2‐Pyrazolin‐5‐on

Investigation of Reactions of Pyrazolin‐Azomethin Dyes with 2‐Pyrazolin‐5‐oneThe pyrazolin‐azomethin dyes (3a–d) from 1‐phenyl‐3‐methyl‐2‐pyrazolin‐5‐one and various photographic developers have been obtained. The reactions of decolourization of dyes during the 3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one action was investigated. We ascertained that the substituent changes in the developer had not only the influence on decolourization rate but they also had influence on the order change of the reaction. The various solvents had the same influence on the reaction rate of decolourization.

Effect of Ultrasonic Waves on Eriochrome Black T

Abstract Ultrasonic waves of high frequency (1 Mc/sec) have been employed to study the effects on the dilute aqueous solution of Eriochrome Black T. The deaeration of the solution by nitrogen does not greatly affect the rate of decolourization. The process is irreversible and the kinetic study shows it to be unimolecular. Oxidation and subsequent destruction of the dye molecule has been found to be the cause of the fading of the dye solution.