Decolorization Treatment Research Articles

Design and Application of Electrochemical Processes for Decolorization Treatment of Nylanthrene Red dye Bearing Wastewaters

Design and Application of Electrochemical Processes for Decolorization Treatment of Nylanthrene Red dye Bearing Wastewaters

Development of a cloud point extraction and spectrophotometry-based microplate method for the determination of nitrite in human urine and blood

A novel and simple method for the sensitive determination of trace amounts of nitrite in human urine and blood has been developed by combination of cloud point extraction (CPE) and microplate assay. The method is based on the Griess reaction and the reaction product is extracted into nonionic surfactant Triton-X114 using CPE technique. In this study, decolorization treatment of urine and blood was applied to overcome the interference of matrix and enhance the sensitivity of nitrite detection. Multi-sample can be simultaneously detected thanks to a 96-well microplate technique. The effects of different operating parameters such as type of decolorizing agent, concentration of surfactant (Triton X-114), addition of (NH4)2SO4, extraction temperature and time, interfering elements were studied and optimum conditions were obtained. Under the optimum conditions, a linear calibration graph was obtained in the range of 10–400ngmL−1 of nitrite with limit of detection (LOD) of 2.5ngmL−1. The relative standard deviation (RSD) for determination of 100ngmL−1 of nitrite was 2.80%. The proposed method was successfully applied for the determination of nitrite in the urine and blood samples with recoveries of 92.6–101.2%.

Electrochemical treatment of actual dye house effluents using electrocoagulation process directly powered by photovoltaic energy

In the present work, the decolorization treatment of colored wastewaters produced from polyamide textile dyeing is studied using the electrocoagulation process with sacrificial aluminum electrodes. The electrical energy is obtained from a solar photovoltaic array by directly connecting it to the electrocoagulator without batteries. The photovoltaic electrocoagulation (PV-EC) system is made versatile according to the instantaneous solar irradiation by adjusting the wastewater flow rate to the current intensity supplied by the photovoltaic array. All the PV-EC experiments were performed in Kavala Institute of Technology (latitude 40°55′, longitude 24°22′, and altitude 138 m above the sea level). The purpose of this paper is to investigate all parameters affecting the efficiency of the process, such as initial wastewater pH, conductivity, operating time, flow rate, and solar irradiation. The efficiency of the EC process was followed by measurements of turbidity and chemical oxygen demand (COD). According to the obtained experimental results, fast and effective decolorization of the treated wastewater occurred in a few minutes of electroprocessing. Turbidity was quantitatively reduced from 103 to 0.2 NTU, amounting to a removal percentage of over 99%, whereas COD was reduced by 65%. The proposed process is appropriate for decolorizing colored textile dye wastewaters and especially for small applications in remote and isolated locations without connection to public electric grid.

Comparison of the potential of Ficus sycomorus latex and horseradish peroxidases in the decolorization of synthetic and natural dyes

The aim of this study was to compare the potential of Ficus sycomorus latex peroxidase (POL) and horseradish peroxidase (HRP) in the decolorization of a wide spectrum of eight synthetic dyes and two natural dyes, hibiscus flower color and pomegranate juice. We study for the first time the decolorization of natural dyes enzymatically. The highest decolorization percent was reported at 20 mg/l for all dyes treated with POL and HRP. Both the enzymes had lower decolorization % for azo-carmin (30–33%). During decolorization treatment, both natural dyes and titan yellow formed precipitates which settled down and were removed by centrifugation. The enhancement of the decolorization % of the most tested dyes by treatment with POL and HRP was reported in the presence of some redox mediators. The rate of decolorization was enhanced by increasing the time and the most significant changes were observed during the first 6 h of incubation. One hundred percent enhancement in decolorization was reported for azo-carmine in the presence of histidine and α-naphthol as redox mediators. A few of redox mediators caused no significant effect or decreases the decolorization % for a little number of tested dyes. The decolorization of dyes by POL and HRP in the presence of redox mediators appeared without the formation of precipitate. A similar decolorization % for all the tested dyes by POL and HRP was detected. The data suggested that the peroxidase/mediator system was an effective biocatalyst for the decolorization of synthetic and natural dyes, and POL could be used as a potential option for the application of dye decolorization.

CdS nanocrystals/TiO2/crosslinked chitosan composite: Facile preparation, characterization and adsorption-photocatalytic properties

CdS nanocrystals deposited on TiO2/crosslinked chitosan composite (CdS/TiO2/CSC) were prepared in an attempt to photocatalyze decolorization of water soluble azo dye in aqueous solution under simulated solar light irradiation. CdS/TiO2/CSC was characterized by X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and scanning electron microscopy (SEM). The characterization results proved that CdS nanocrystals has successfully been deposited on/in TiO2/crosslinked chitosan composite. The adsorption ability of CdS/TiO2/CSC was approximately 2.66mg methyl orange (a typical water soluble azo dye) per gram. The photocatalytic decolorization of methyl orange solution reached 99.1% by CdS/TiO2/CSC after simulated solar light irradiation for 210min. Kinetics analysis indicated that photocatalytic decolorization of methyl orange solution by CdS/TiO2/CSC obeyed first-order kinetic Langmuir-Hinshelwood mechanism (R2>0.997). CdS/TiO2/CSC exhibited enhanced photocatalytic activity under simulated solar light irradiation compared with photocatalysts reported before and the photocatalytic activity of CdS/TiO2/CSC maintained at 89.0% of initial decolorization rate after five batch reactions. The presence of NO3− accelerated the decolorization of methyl orange solution by CdS/TiO2/CSC, while SO42− and Cl− had an inhibitory effect on the decolorization of methyl orange. Therefore, present experimental results indicated to assess the applicability of CdS/TiO2/CSC as a suitable and promising photocatalyst for effective decolorization treatment of dye-containing effluents.

Decolorization of textile wastewater using the white rot fungi anamorph R1 of Bjerkandera sp.

Decolorization of synthetic and industrial wastewaters from textile industry by the anamorph R1 of white rot fungiBjerkandera sp. was evaluated. The presence of NaCl and Na2CO3 wastewater concentration and treatment with non-sterile wastewater on decolorization were analyzed. In addition, the decolorization effect on wastewater toxicity was analyzed with Vibrio fischerias target microorganism. The presence of salts in the treatment increased the lignin peroxidase activity from 5 to 20 U/L, without detriment of manganese peroxidase activity which remained at 70 U/L, also. The presence of salts also enhances dye adsorption degree over fungi biomass, improving the decolorization by the two mechanisms, degradation and adsorption. In hipersaline synthetic wastewater, the percentage of decolorization was 75%. The decolorization treatment of sterile textile effluents reached 65% in 8 days and the toxicity reduction was 58% with respect to untreated textile effluents. In non-sterile textile effluents, only 40% of decolorization was obtained. The presence of contaminant microorganisms which compete by substrate and increase pH by fungus metabolism, were likely the main causes of low decolorization.

Decolorization Treatment of Copper Phthalocyanine Textile Dye Wastewater by Electrochemical Methods

Electrochemical decolorization and degradation treatment of aqueous copper phthalocyanine reactive dye solutions was comparatively studied by electrocoagulation, electrooxidation and electro-Fenton processes. In the electrocoagulation process with aluminum electrodes the colored aqueous solutions of initial pH 6.4 containing 50 mg L-1 copper phthalocyanine and 6 g L-1 NaCl were treated at applied current densities of 2.5 and 5 mA cm-2. Fast and 100% decolorization was achieved in 4 and 2 minutes of electroprocessing respectively. The indirect electrooxidation process was conducted in acidic electrolyte solutions containing 50 mg L-1 copper phthalocyanine and 6 g L-1 NaCl with Ti/Pt and graphite plate electrodes at the applied current density of 10 mA cm-2. Even after 90 minutes of electrolysis time the dye remained by 23 and 18.8 % respectively undegradable. By the direct and indirect electrooxidation with the same amount of Na2SO4 electrolyte and added H2O2 respectively and using the same electrodes, the copper phthalocyanine dye was not or was only barely degraded respectively. In the electro-Fenton process with Fe electrodes and added amounts of H2O2 at pH 3 and an applied current density of 5 mA/cm2 complete degradation of copper phthalocyanine occurred in 15 minutes.

Microbial deterioration of archaeological marble: Identification and treatment

Microbial deterioration of archeological marble was studied on samples taken from three locations in Cairo, Egypt; Mohamed Ali palace, El-Ghory Mosque and Mosque of El-Kady Abdel-Baset. Sampling resulted in 110 microbial isolates, identified as eight fungal genera, three bacterial genera, one actinomycetes genus and six algae. Isolated strains were all identified up to species. The inhibitory effect of five antimicrobial agents at various concentrations was investigated against the growth and development of these microbial isolates. Sodium azide at 100ppm was found to be the best treatment for both fungal and bacterial isolates. Colored spots, caused by microbial growth, were treated by different synthetic and natural chemical substances. Results showed also that microbial enzymes produced by Aspergillus flavus isolate was the best decolorization treatment.

Decolorization and Detoxication of Reactive Industrial Dyes by Immobilized Laccases

Laccase immobilized on polyurethane foam cubes in bioreactors, were used to decolorize three industrial and model dyes at concentrations of 200, 1000 and 2000 ppm. Five sequential cycles were run for each dye and fungus. The activity of laccase, Mn-dependent and independent peroxidases, lignin peroxidase, and aryl-alcohol oxidase were daily monitored during the cycles and the toxicity ofmedia containing 1000 and 2000 ppm of each dye was assessed by the Lemna minor (duckweed) ecotoxicity test. Laccase was able to efficiently decolorize all dyes even at the highest concentration, and the duckweed test showed a significant reduction (p≤ 0.05) of the toxicity after the decolorization treatment. Laccase activities varied greatly and no clear correlation between decolorization and enzyme activity was obselved a high laccase activity during decolorization cycles. Laccase showed better decolorization and detoxication capability.

Electrocoagulation treatment of simulated floor-wash containing Reactive Black 5 using iron sacrificial anode

Floor-wash from dye finishing plant is a major source of color and wastewater volume for dyes industries. Batch electrocoagulation (EC) of simulated floor-wash containing Reactive Black 5 (RB5) was studied as a possible pretreatment option. More than 90% of initial 25mg/L of RB5 was removed at current densities of 4.5, 6, and 7.5mA/cm2 in the presence of Na2SO4 and NaCl as supporting electrolytes; in less than one hour. Identical kobs (pseudo first-order reaction rate constant) values were obtained at initial pH of 3.74 for both electrolytes. However, at initial pH of 6.6, kobs values decreased in the presence of Na2SO4 and remained same for NaCl as compared to that at pH 3.74. Highest extent of decolorization and kobs values were obtained at initial pH 9.0 for both electrolytes. Under identical conditions, specific energy consumption (SEC) was almost half in the presence of NaCl (∼29kWh/kgRB5) than that of Na2SO4. Vinyl sulfone (VS) was detected as one of the products of EC indicating reduction of azo bonds as a preliminary step of decolorization. Mechanism of decolorization with respect to various experimental conditions was delineated. Generation and accumulation of VS was dependent on initial pH and type of electrolyte. Results of this study revealed that EC in the presence of sodium chloride can be efficiently used as a primary treatment for decolorization of floor-wash containing RB5.

Decolorization and degradation of azo dye Methyl Red by an isolated Sphingomonas paucimobilis: Biotoxicity and metabolites characterization

Azo dyes are recalcitrant and refractory pollutants that constitute a significant burden on the environment. The report here is focused on the decolorization treatment of water soluble azo dye Methyl Red (MR). Sphingomonas paucimobilis, was isolated from the effluent treatment plant of a textile and dyeing industry (SITEX) located in KsarHellal, Tunisia. At shaking condition this strain showed 99.63% decolorization of a toxic azo dye MR (750 ppm) within 10 h in a Mineral Salt Medium (MSM) at 30 °C and pH 9. The degradation of MR was possible through a broad pH (3–11) and temperature (5–40 °C) range. Untreated dye at 750 mg/1 concentration showed 30% germination inhibition in Sorghum bicolor, whereas it was 55% in Triticum aestivum. There was no germination inhibition for both the plants by MR metabolites at 750 ppm concentration. The degradation products were characterized by UV–visible and Fourier Transform Infrared Spectroscopy (FTIR), their toxicity with respect to Artemia salina was evaluated. The scientific relevance of the paper: the azo dye MR (750 ppm) was decolorized by S. paucimobilis within 10 h at shaking condition in MSM. This organism could decolorize MR at wide pH and temperature ranges.

Optimization of biological treatment of a dye solution by macroalgae Cladophora sp. using response surface methodology

In this paper biological treatment of Malachite Green (MG) solution using macroalgae Cladophora sp. has been reported. Response surface methodology (RSM) was employed to investigate the effect of key factors on the biological treatment. The variables investigated were the initial pH, initial dye concentration, algae amount and reaction time. Central composite design (CCD) was used for the optimization of biological decolorization process. Predicted values were found to be in good agreement with experimental values ( R 2 = 0.9740 and Adj- R 2 = 0.9512), which indicated suitability of the model employed and the success of CCD in optimizing the conditions of biological decolorization process. The results of optimization predicted by the model showed that maximum decolorization efficiency was achieved at the optimum condition of the initial pH 8, initial dye concentration 10 mg/l, algae amount 4 g and reaction time 75 min. Biological degradation of MG was revealed on the basis of live and dead biomass comparison, repeated-batch operations and UV–Vis, FT-IR spectra of MG solution during biological decolorization treatment.

The effect of combination enzymatic and advanced oxidation process treatments on the colour of pulp and paper mill effluent

The efficiency of advanced oxidation processes (AOPs), enzymatic treatment and combined enzymatic/AOP sequences for the colour remediation of soda and chemimechanical pulp and paper mill effluent was investigated. The results indicated that under all circumstances, the AOP using ultraviolet irradiation (photo‐Fenton) was more efficient in the degradation of effluent components in comparison with the dark reaction. It was found that both versatile peroxidase (VP) from Bjerkandera adusta and laccase from Trametes versicolor, as pure enzymes, decolorize the deep brown effluent to a clear light‐yellow solution. In addition, it was found that in the laccase treatment, the decolorization rates of both effluents were enhanced in the presence of 2, 2’‐azinobis (3‐ethylbenzthiazoline‐6‐sulfonate), while in the case of by VP, Mn+2 decreased the efficiency of the decolorization treatment. The concomitant use of enzymes and AOPs imposes a considerable effect on the colour remediation of effluent samples.

Rapid decolorization of azo dye methyl orange in aqueous solution by nanoscale zerovalent iron particles

Azo dyes are recalcitrant and refractory pollutants that constitute a significant burden on the environment. The report here is focused on the decolorization treatment of water soluble azo dye methyl orange (MO) by chemically synthesized nanoscale zerovalent iron (NZVI) particles. Experimental variables such as initial dye concentration, iron dosage, solution pH and temperature were studied systematically. Batch experiments suggest that the decolorization efficiency was enhanced with the increase of NZVI dosage and reaction temperature, but decreased with increasing initial dye concentration and initial solution pH. Further studies indicated that existence of inorganic salt (Na 2SO 4) could inhibit the decolorization of MO. Kinetic analyses based on the experimental data elucidated that the decolorization process followed a first order exponential decay kinetics model. The activation energy was determined to be 35.9 kJ/mol.

Decolorization and detoxication of reactive industrial dyes by immobilized fungi Trametes pubescens and Pleurotus ostreatus

Trametes pubescens and Pleurotus ostreatus, immobilized on polyurethane foam cubes in bioreactors, were used to decolorize three industrial and model dyes at concentrations of 200, 1000 and 2000 ppm. Five sequential cycles were run for each dye and fungus. The activity of laccase, Mn-dependent and independent peroxidases, lignin peroxidase, and aryl-alcohol oxidase were daily monitored during the cycles and the toxicity of media containing 1000 and 2000 ppm of each dye was assessed by the Lemna minor (duckweed) ecotoxicity test. Both fungi were able to efficiently decolorize all dyes even at the highest concentration, and the duckweed test showed a significant reduction (p < or = 0.05) of the toxicity after the decolorization treatment. T. pubescens enzyme activities varied greatly and no clear correlation between decolorization and enzyme activity was observed, while P. ostreatus showed constantly a high laccase activity during decolorization cycles. T. pubescens showed better decolorization and detoxication capability (compared to the better known P. ostreatus). As wide differences in enzyme activity of the individual strains were observed, the strong decolorization obtained with the two fungi suggested that different dye decolorization mechanisms might be involved.

Revealing threshold criteria of biostimulation for dye-laden wastewater treatment using immobilized cell systems

This study provides a first attempt from a process dynamic perspective to put forward, in general terms and explanations, threshold criteria of dye-laden wastewater treatment using immobilized cell systems (ICSs). Porites corals were selected as packing matrices of ICSs in demonstration of immobilized cell treatment for dye decolorization. With a staircase ramp input of dye in the inlet stream, significant losses of biodecolorization activity were gradually emerged when dye concentrations went over critical loadings for treatment. Design equations also disclosed that the decay rate constant decreased from infinity to a finite value directly caused an operation failure in ICS. According to mean value theorem, the proposed threshold criteria (e.g., maximal allowable treatment capacity) in ICSs could be determined by the method of a constant-slope isocline family, directly indicating treatment limits at various nutrient media in biostimulation.

Natural polysaccharides and their interactions with dye molecules: applications in effluent treatment.

Dyeing effluent is one of the largest contributors to textile effluent and such colored wastewater has a seriously destructive impact on the environment. Adsorption can be a very effective treatment for decolorization of textile dyeing effluent, but current techniques employ adsorption chemistry that is not particularly environmentally friendly, such as the use of alum. In this study, natural polysaccharides were used as adsorbents for removal of dye molecules from effluent. The results showed that naturally cationic polysaccharides such as chitin and chitosan gave excellent levels of color removal, and this was attributed to a combination of electrostatic attraction, van der Waals forces, and hydrogen bonding. Nonionic galactomannans (locust bean gum, guar gum, cassia gum) were also highly effective in removing dye from effluent, whereas other nonionic polysaccharides, such as starch, were not effective. This was attributed to the structure of the polysaccharides and the relative degree of inter- and intramolecular interactions between separate polymer chains. The pendant galactose residues of galactomannans prevented strong interaction, allowing greater hydrogen bonding with dye; comparatively, starch has extensive chain interactions, and as such had limited potential for hydrogen bonding with the dye molecules at the temperature of application. In addition, hydrophobic interactions between the hydrophobic parts of the dye and the alpha-face of the pendant galactose residues may have contributed to the superior performance. Repulsion between anionic polysaccharides and the dye anions prevented any hydrogen bonding and as such pectin, carrageenans, and alginic acid were not effective in dye removal from effluent. The use of galactomannans derived from plants in this system presents a sustainable method of effluent treatment. The raw materials are derived from renewable plant sources and are available in tonnage quantities, the adsorption system itself is highly effective and does not involve any additional chemical input or treatment other than the use of the adsorbent, and the adsorption agents themselves are nontoxic and biodegradable.

電気分解を利用した糖蜜廃液の脱色処理 電極材料の影響と実用化の検討

In the decolorization treatment of molasses wastewater by electrolysis, the effect of anode material on the decolorization efficiency (η) was studied. Five soats of anode material, which are PdO, PbO2, IrO2, Pt and graphite, were certified under the electrolysis condition of wastewater from an alcohol distillery with 5% NaCl. PdO was the most effective anode. η with PdO was 750U·l·kC-1 three times larger than η with Pt, and η with graphite was 470U·l·kC-1. In order to study for practical use, the pilot scale electrolysis reactor was made with a graphite anode and a stainless steel cathode. When methane fermentation was used for pre-treatment and the treated water diluted with sea water, η was obtained the highest value. The energy balance of the glutamate wastewater treatment system which was conbined a methane fermentation, electrolysis decolorization and co-generation was estimated. The recovery electric energy from co-generation was calculated as 75% of the required electric energy for electrolysis decolorization.

Advanced treatment of dyeing wastewater for reuse

As one of the main pollution sources in Hong Kong, the textile dyeing and finishing industry creates a significant proportion of water pollution in nearby harbour zones. Generally speaking, conventional biological treatment processes have difficulties in degrading many dye chemicals causing high COD and colour in dyeing wastwaters. Studies using physical and chemical processes to further reduce COD and colour from dyeing wastewater have been intensively reported. The use of a photocatalytic process in the presence of TiO2 to degrade many different types of dye chemicals has been confirmed. However, how to efficiently separate and reuse TiO2 from treated wastewater became a notable problem in the application of a TiO2 photo-oxidation process. This study aims to develop an advanced treatment process for dyeing wastewater treatment. In which dyeing wastewater was initially treated by an Intermittently Decanted Extended Aeration (IDEA) reactor to initially remove those biodegradable matters and further treated by a TiO2 photocatalytic reactor as advanced treatment for complete decolorization and high COD removal. Suspended TiO2 powder used in photooxidation was separated from slurry by a membrane filter and recycled to the photoreactor continuously. The results demonstrated that photocatalytic-oxidation process could degrade those non-biodegradable organic substances in the effluent treated by the biological treatment process and also remove the colour from the effluent completely. TiO2, as catalyst, was successfully recovered by a membrane filter and continuously reused in the photoreactor. The quality of dyeing wastewater treated by the advanced treatment process can be good enough for reuse in the textile dyeing processes.

電気分解を利用した糖蜜廃液の脱色処理 脱色効率に及ぼす電解条件の影響

Molasses wastewater has been disposed by ocean dumping because of the dark brown color. However, ocean dumping will banned near future according to London dumping treaty. Many fermentation and sugar industries using molasses require the suitable decolorization treatment. Electrolysis for decolorization was applied for molasses wastewater, mainly wastewater from alcohol distillery, and high decolorization efficiency more than 99% was obtained. The optimal initial condition of color by dilution was 200,000U without NaCl addition. NaCl addition was effective to raise decolorization efficiency which shows the decolorization by unit electron quantity The voltage and initial pH did not effect the efficiency. The experiments using wastewater from glutamate processing industry, sugar processing industry and sugar refinery industry also showed the effectiveness of electrolysis for decolorization.