1. Decolorization and mineralization of reactive dyes, by the $H_2O_2$/UV process with electrochemically produced $H_2O_2$Tina Jerič, Roel J. M. Bisselink, Willy Van Tongeren, Alenka Majcen Le Marechal, 2013, original scientific article Abstract: Decolorization of Reactive Red 238, Reactive Orange 16, Reactive Black 5 and Reactive Blue 4 was studied in the UV/$H_2O_2$ process with $H_2O_2$ being produced electrochemically. The experimental results show that decolorization increased considerably when switching on the electrochemical production of $H_2O_2$. Complete decolorization (>99%) was achieved for all dyes under the applied experimental conditions, partial mineralization (49-85%) was obtained, which depends on the type of dye. Reactive Red 238 was used to investigate operational parameters and it was found that decolorization was influenced by the applied electrical current of the electrochemical cell and flow rate. Decolorization and mineralization of Reactive Red 238 can be described by pseudo-first order kinetics. It was found that the initial concentration of Reactive Red 238 has a negative influence on the pseudo-firstorder reaction constant.
Keywords: decolorization, hydrogen peroxide, reactive dyes, in-situ $H_2O_2$, AOP, Reactive Red 238
Published in DKUM: 10.07.2015; Views: 1564; Downloads: 81
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2. Reactive dye decolorization using combined ultrasound/H2O2Darinka Brodnjak-Vončina, Alenka Majcen Le Marechal, 2003, original scientific article Abstract: The decolorization of six vinylsulphone reactive dyes (C.I. Reactive Yellow 15, C.I. Reactive Red 22, C.I. Reactive Blue 28, Remazol Dark Black N 150%, C.I. Reactive Blue 220 and C.I. Reactive Black 5) in aqueous solution was investigated using ultrasound and ultrasoundž hydrogen peroxide degradation. Two different concentration levels of hydrogen peroxide were used. The efficiency of the decolorization was evaluated by measuring the absorbance of the dye solutions. The results show that ultrasound treatment was significantly enhanced in the presence of H2O2.
Keywords: ultrasonic irradiation, decolorization, oxidation processes, hydrogen peroxide, reactive dyes, vinylsulphone reactive dyes
Published in DKUM: 01.06.2012; Views: 2377; Downloads: 102
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3. Comparison of H2O2/UV, H2O2/O3 and H2O2/Fe2+ processes for the decolorisation of vinylsulphone reactive dyesTanja Kurbus, Alenka Majcen Le Marechal, Darinka Brodnjak-Vončina, 2003, original scientific article Abstract: Six vinylsulphone reactive dyes were decolorised using three oxidation processes (H2O2/UV, H2O2/O3 and H2O2/Fe2+). The efficiency of decolorisation was measured by decolorisation time, absorbance, COD and TOC and the three methods of decolorisation are compared.
Keywords: textile reactive dyes, vinylsulphone dyes, decolorisation, hydrogen peroxide, UV irradiation, ozone, Fenton's reagent, pollution parameters, experimental design
Published in DKUM: 01.06.2012; Views: 2182; Downloads: 106
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4. Residual dyebath purification using a system of constructed wetlandAlenka Ojstršek, Darinka Fakin, Danijel Vrhovšek, 2007, original scientific article Abstract: A constructed wetland model, comprising two different substrate mixtures, was used to purify textile dyebath wastewater. Three laboratory prepared wastewaters containing three commercial dyes of different classes and chemicalconstitution (one vat and two reactive dyes), different chemicals (NaOH, NaCl) and auxiliaries (migration inhibitor, sequestering, defoaming andwetting agents) were employed. Purifying efficiency was verified by measuring pollution parameters, such as absorbance, pH, total organic carbon (TOC), chemical oxygen demand (COD) and electrical conductivity (EC). It was found that the constructed wetland model reduced dye concentration by up to 70%, lowered the TOC and COD values up to 88%, electrical conductivity up to 60% and pH from 12 to 7.6.
Keywords: textile dyeing, reactive dyes, vat dyes, wastewater treatment, constructed wetland model, biological treatment, purification
Published in DKUM: 01.06.2012; Views: 2315; Downloads: 100
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5. Case study of the sonochemical decolouration of textile azo dye Reactive Black 5Simona Vajnhandl, Alenka Majcen Le Marechal, 2007, original scientific article Abstract: The decolouration and mineralization of reactive dye C.I. Reactive Black 5, a well-known representative of non-biodegradable azo dyes, by means of ultrasonic irradiation at 20, 279 and 817 kHz has been investigated with emphasis on the effect of various parameters on decolouration and degradation efficiency. Characterization of the used ultrasound systems was performed using calorimetric measurements and oxidative species monitoring using Fricke and iodine dosimeter. Experiments were carried out with low frequency probe type, and a high-frequency plate type transducer at 50, 100 and 150 W of acoustic power and within the 5-300 mgžL initial dye concentration range. Decolouration, as well as radical production, increased with increasing frequency, acoustic power, and irradiation time. Any increase in initial dye concentration results in decreased decolouration rates. Sonochemical decolouration was substantially depressed by the addition of 2-methyl-2-propanol as a radical scavenger, which suggests radical-induced reactions in the solution. Acute toxicity to marine bacteria Vibrio fischeri was tested before and after ultrasound irradiation. Under the conditions employed in this study, no toxic compounds were detected after 6 h of irradiation. Mineralization of the dye was followed by TOC measurements. Relatively low degradation efficiency (50% after 6 h of treatment) indicates that ultrasound is rather inefficient in overall degradation, when used alone.
Keywords: textile industry, wastewater treatment, textile dyeing, reactive dyes, azo dyes, decoloration, ultrasound, degradation, decoloration kinetics, oxidizing species
Published in DKUM: 01.06.2012; Views: 2250; Downloads: 98
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6. Efficiency of the coagulation/flocculation method for the treatment of dyebath effluentsVera Golob, Aleksandra Vinder, Marjana Simonič, 2005, original scientific article Abstract: Textile dyeing processes are among the most environment-unfriendly industrial processes, because they produce coloured wastewaters that are heavily polluted with dyes, textile auxiliaries and chemicals. The coagulation/flocculation method was studied as a wastewater treatment technique for the decolourization of residual dyebath effluents after dyeing cotton/polyamide blends using reactive and acid dyes. It was discovered that acombination of aluminium sulphate and a cationic organic flocculant yields an effective treatment for residual dyebath wastewaters since almost complete decolourization was achieved, TOC, COD, AOX, BOD and the anionic surfactants were reduced and the biodegradability was increased.
Keywords: textile industry, reactive dyes, acid dyes, wastewater, čiščenje odpadnih vodwastewater treatment, flocculation, coagulation, ecological analyses, wastewater decoloration, Jar-tests
Published in DKUM: 01.06.2012; Views: 2444; Downloads: 103
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7. Wastewater treatment after reactive printingSonja Šostar-Turk, Marjana Simonič, Irena Petrinić, 2005, original scientific article Abstract: Membrane filtration of wastewater after textile printing with reactive dyes isdescribed. The wastewater from a Slovenian factory, whose output is approx. 80% reactive dyes printed and dyed on cotton, was studied. In particular, the presence of urea, sodium alginate, oxidation agent and reactive dyes, used forthe printing paste preparation, in the wastewater was studied. Chemical analyses of actual, non-purified, wastewater showed that many Slovenian regulations were exceeded. The study of membrane filtration is based on a pilot wastewater treatment plantČ ultrafiltration (UF) and reverse osmosis (RO) units. The quality of the wastewater was improved by ultrafiltration, butits effluent still does not conform to the specification of concentration limits for emission into water. Permeate coming from RO meets the required specification and, therefore, could be re-used in the washing process of printed textiles.
Keywords: textile printing, reactive dyes, wastewater treatment, membrane filtration, pilot plant
Published in DKUM: 01.06.2012; Views: 3369; Downloads: 93
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