Synergistic Decolouration of Azo Dye by Pulsed Streamer Discharge Immobilized TiO_2 Photocatalysis

Photocatalyst was prepared by immobilizing TiO2 on glass beads using the traditional sol-gel method. Ultraviolet light （UV） produced by pulsed streamer discharge was then used to induce photocatalytic activity of TiO2 photocatalyst. Decolouration efficiency of the representative azo dye （acid orange 7, AOT） was investigated using the synergistic system of pulsed streamer discharge plasma and TiO2 photocatalysis. The obtained results showed that the decolouration rate of AO7 could be increased by 16.7% under the condition of adding supported TiO2 in the pulsed streamer discharge system, compared to that in the sole pulsed streamer discharge plasma system, due to the synergistic effect of pulsed streamer discharge and TiO2 photocatalysis induced by pulsed streamer discharge. The synergistic system of pulsed streamer discharge and TiO2 photocatalyst was found to have more reactive radicals for degradation of organic compounds in water.

Treatment of Practical Dye Wastewater Using a Double Dielectric Barrier Discharge System Combined with a Sequencing Batch Reactor System

Synthetic dyes are substances that are relatively stable and difficult to degrade in wastewater treatment plants using normal physical,chemical or / and biological treatment. The present work explored the synergistic effect of non-thermal plasma( NTP) and biological wastewater treatment technologies on practical dye wastewater degradation by establishing a double dielectric barrier discharge( DDBD) system combined with a sequencing batch reactor( SBR) system. The biodegradation and degradation efficiency of the DDBD-SBR system was investigated. The investigation results indicated that the DDBD technology was effective in treating the practical dye wastewater as a pre-treatment process. After a 10-min treatment,although the total organic carbon( TOC) removal efficiency was not so significant, the decolouration and the biodegradation were improved greatly. The microbial toxicity test revealed that the sample after degradation became less toxic than the original dye,which demonstrated the treatment had a significant effect on the reduction of toxicity. In addition,the SBR technology remedied the defects of DDBD treatment and improved TOC removal efficiency noticeably. The hybrid DDBD-SBR system made full use of the advantages of the individual technologies and exhibited an efficient capability for practical dye wastewater treatment.

浅议某静电植绒厂废水处理

本文通过小试与工程实践指出:对某静电植绒厂含酸性染料废水处理采用混凝与活性炭吸附工艺的物化处理方法是可行的。这种方法尤其适合于小型印染厂;如有必要时还可解决废水的回用问题。

Experiments on decolourization with 122-resin for extraction of gib-berellins from solid medium under different conditions

The extracting liquid of gibberellins (Gibberella fujikuroi) from solid medium for was decolorized separately with 75%, 95% alcohol, and distilled water in static adsorption and vibrating way for different durations. The results showed that the content of GA3 in efflux extracted with alcohol is 10% higher than that with distilled water. With the increase of the durations of extraction, the content of GA3 increases and the dissolution of pigments also increase. For extraction of GA3 cultured in solid medium, the best decolorizing result was obtained when it was extracted with 75%-95% alcohol in static way for 1-3 h, or in a vibrating way for 30-60 min, and then to decolor in a static way for 30-60 min in 122 resin column.

Degradation Mechanism of Cationic Red X-GRL by Ozonation

The degradation mechanism of Cationic Red X-GRL was investigated when the intermediates, the nitrate ion and the pH were analyzed in the ozonation. The degradation of the Cationic Red X-GRL includes the de-auxochrome stage, the decolour stage, and the decomposition of fragment stage. During the degradation process, among the six nitrogen atoms of Cationic Red X-GRL, one is transferred into a nitrate ion, one becomes the form of an amine compound, and the rest four are transformed into two molecules of nitrogen. In the course of the ozonation of Cationic Red X-GRL, the direct attack of ozone is the main decolour effect.

Decolourization of Reactive Brilliant Blue KN-R by immobilized cells of Aspergillus ficuum

Aspergillus ficuum was immobilized with sodium alginate, and decolourization of Reactive Brilliant Blue KN-R was studied on immobilized and free Aspergillus ficuum. The optimal preparation condition of the strain immobilization was obtained by the orthogonal test, it is sodium alginate 3%, CaCl_2 5%, wet mycelia 30 g/L, calcific time 8 h. It was found that the immobilized cells could effectively decolourize Reactive Brilliant Blue KN-R, the optimum temperature and pH were 33℃ and 5.0, respectively. The kinetics study of decolourization of immobilized cells showed that the decolourization of Aspergillus ficuum immobilized conformed to zero-order reaction model. The decolourization efficiency of immobilized cell compared with that of free cell in different physical conditions. Results showed that the decolourization of immobilized cells with mycelia had the best efficiency. The immobilized cells could be reused after the first decolourization.

Washing-off of Unfixed Reactive Dyes on Cotton Fabrics Using Fe-TAML/H_2O_2 Catalyzed Oxidation System

Unfixed reactive dyes stained on cotton fabric could be removed using Fe-tetra-amido macro-cyclic ligands( TAML) / H_2O_2 catalyzed oxidation system( COS). The colored washing-off wastewater also could be decolorized simultaneously in the same system. The decolourization kinetics showed that the decolourization ratio of reactive dyes in water could reach at least 80% at room temperature in 10 min,which followed the law of pseudo-first order reaction kinetics. The effects of the COS washing-off process parameters on the decolourization ratio,chemical oxygen demand( COD) of wastewater,K/S value,color fastness,color difference,and bursting strength were investigated in detail. The results showed that color fastness properties and final shade of fabric treated by COS were very similar to conventional soaping. The reactive dye molecules in wash-off bath were destroyed using the COS,potentially reduced COD which generated during conventional washing-off procedure.

Photo-Degradation of Reactive Yellow 14 Dye (A Textile Dye) Employing ZnO as Photocatalyst

In this paper, the reactive yellow 14 dye solution was removed from aqueous solution in the presence of commercial ZnO (mean crystallite size is 44.116 nm) under the UV A light. The decolourization of dye process was obeyed to pseudo-first orderkinetics. The optimum conditions of decolourization for this dye such as: initial dye concentration 50 mg/L, best dose of ZnO 350 mg/100mL and initial pH of aqueous solution of dye 6.75 were studied. Activation energies for dye were found to be 27.244 kJmol-1. The photoreaction process was observed to be endothermic reaction and less randomness.

A Highly Sensitive Kinetic Spectrophotometric System and Its Analytical Potential for Chromatographic Detection of Metal Ions

Based on the inhibitory effect of metal ions on the decolourization reaction of a dye taking place in a mixed micellar medium, a differential rate method was developed for the detection of metal ions. The present kinetic spectrophotometric system has several advantages due to introduction of the mixed micelles.

A NEW COMPOUNDING COAGULANT FOR DECOLOURIZATION

This paper explores a new compounding coagulant for decolourization, which can decolour wastewater containing soluble dyestuffs (especially reactive and acidic dyestuffs). The best prescription and condition of this decolourizing process are discussed and the mechanism is studied. Experimental results show that the treatment efficiency of decolourization is very high by using the new coagulant. Both the colour and pH of the effluent meet the required standards. The synergism of chemical and physico-chemical actions among the coagulant components has also been found. This effect determines the superiority of the new coagulant to other single component ones.

Biotransformation of Carmoisine and Reactive Black 5 Dyes Using <i>Saccharomyces cerevisiae</i>

Saccharomyces cerevisiae (baker’s yeast) is the most important industrial microorganisms. This yeast is commonly used as a leavening agent in baking bread and bakery products, where it produces carbon dioxide from converting of the fermentable sugars present in the dough. Nowadays, industrial and chemical activities led to produce new compounds with new kinds of contamination in the environment. Discharge of untreated or partially treated industrial sewage has created the contamination problems of rivers and lakes such as drugs, oil, heavy metals, paints, pesticides and various chemical compounds in them. Hence, it is necessary to control and reduce the levels of these compounds in wastewater and bring them to permissible values. This study aims to study the bioconversion potential of commonly available Saccharomyces cerevisiae for the two textile dyes of Carmoisine and Reactive Black 5. Reaction mixtures for biotransformation of dyes included 50 mg/l Carmoisine or 25 mg/l Reactive Black 5 and 1% dried harvested cells of S. cerevisiae (bread’s yeast) were tested. Harvested dry and wet yeast were studied for this purpose. The results show that harvested cells of Saccharomyces cerevisiae are able to bioconvert Carmoisine and Reactive Black 5. Reactive Black 5, Carmoisine are degraded by biotransformation 85% and 53% within 24 hours in water at the room temperature.

Biodegradation of Congo Red Azo Dye by Aspergillus spp, Isolated from Dye Contaminated Soils

In the present study, it has been aimed to determine the non target effects of Congo red on soil enzyme activities namely amylase, protease, catalase, glucose oxidase and laccases, following the standard procedures. Further, it is also aimed to decolourize the dye effluents by using immobilized fimgal cultures namely Aspergillus spp. isolated from textile effluents and estimate the percentage of decolourization by dye decolourization assay method. The selected fungi were found efficient and dominant type in dye decolourization with the production of laccase and other enzymes. Except laccase, all the enzymes showed maximum activity at 14 days followed by declining trend at 21 days. Maximum enzyme activity was noticed with Aspergillus niger. 95% of decolourization was found within 4-24 h in sodium alginate immobilized fungal cultures compared to controls. The above results clearly indicate the efficiency of these fungi in selective bioremediation of dye contaminated sites.

Modelling the Biomass Growth and Enzyme Secretion by the White Rot Fungus <i>Phanerochaete Chrysosporium</i>in Presence of A Toxic Pollutant

The white rot fungus Phanerochaete chrysosporium is well known for its ability to degrade toxic pollutants owing to its efficient extracellular ligninase system. However, biomass growth and enzyme secretion in presence of toxic pollutant is not well understood. In the present study, using the model azo dye Direct Red-80, biomass growth and lignin peroxidase secretion by the fungus was studied during its degradation and a stochastic based model was applied to simulate the behavior of the fungus. Also, glucose concentration in the medium was varied in order to observe its effect on the dye degradation. Results revealed that glucose at an optimum concentration of 10 gL-1 is essential for biomass growth, LiP secretion, as well as the dye decolourization. Modeling the behavior of the fungus with the presence of both glucose and dye has shown significant similarity.

Colour Reflectance Investigation of Decolourized Sulfur Dyed Cotton Knitted Fabric via Ozone Plasma Treatment

Ozone plasma treatment is accessible to be applied on shading adjustment and colour fading because of the capacity of ozone production. It is a green process that treats dyed cotton fabric under dry condition so as to avoid chemical pollutants. This study means to explore colour reflectance of decolourized sulfur dyed cotton texture using ozone plasma treatment. Sulfur dyed cotton textures with various colour depths (0.5%, 1.5%, 2.5%) were set up to be treated different plasma parameters, including ozone air concentrations (10%, 30%, 50%, 70%), water contents in terms of weight percentage (35%, 45%) of fabric and ozone air plasma treatment periods (10 mins, 20 mins, 30 mins). The colour fading result is assessed by the colour reflectance in percentage (R%) utilizing spectrophotometer under CIE standard illuminant D65. The valid colour fading based on high percentage of reflectance was demonstrated from plasma treatment under higher ozone air concentration (50% and 70% ozone in air) and longer time length of plasma treatment (20 mins and 30 mins). The level of water content contained in the cotton fabrics is appeared to have noteworthy relationship with the degree of decolourization.

Degradation of direct azo dye by Cucurbita pepo free and immobilized peroxidase

Enzymatic decolourization of the azo dye, Direct Yellow （DY 106） by Cucurbita pepo （courgette） peroxidase （CP） is a complex process, which is greatly affected by pH, temperature, enzyme activity and the concentrations of H202 and dye. Courgette peroxidase was extracted and its performance was evaluated by using the free-CP （FCP） and immobilized-CP （ICP） forms in the decolourization of DY106. Immobilization of peroxidase in calcium alginate beads was performed according to a strategy aiming to minimize enzyme leakage and keep its activity at a maximum value by optimizing sodium alginate content, enzyme loading and calcium chloride concentration. The initial conditions ~it which the highest DY106 decolourization yield was obtained were found at pH 2, temperature 20~C, H202 dose 1 mmol/L （FCP） and 100 mmol/L （ICP）. The highest decolourization rates were obtained for dye concentrations 50 mg/L （FCP） and 80 mg/L （ICP）. Under optimal conditions, the FCP was able to decolorize more than 87% of the dye within 2 min. While with ICP, the decolourization yield was 75% within 15 rain. The decolourization and removal of DY106 was proved by UV-Vis analysis. Fourier transform infrared （FF-IR） spectroscopy analysis was also performed on DY106 and enzymatic treatment precipitated byproduct.

Kinetics and products of ozonation of C.I.Reactive Red 195 in a semi-batch reactor

Textile wastewater shows great threats to the environment if not well pretreated before discharge. A promising technique, ozonation, was applied to remove the color in dye solutions containing C.I. Reactive Red 195 （RR195） in a semi-batch reactor. The decolorization of RRI95 by the ozone process followed pseudo-first-order kinetics. Several factors which influenced the efficiency of decolorization were studied and the reaction rate constant （k） obtained with different operational parameters was compared. Our results showed that RRI95 was more easily degraded in acidic than in alkaline conditions. The dyeing auxiliaries （sodium carbonate and sodium chloride） that acted as radical scavengers could enhance the decolorization process, and the ozonation time for total color removal lengthened if the initial dye concentration was higher. The analysis of the ozonation products was performed by liquid chromatography-tandem mass spectrometer and a possible degradation pathway was predicted according to the ozonation products and structure of RR195. Our results indicated that ozonation was effective in the color removal of dyes, but further treatment might be necessary since the ozonation products are high toxic.