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1.
The decolorization of some of azo‐metal complex dyes used in textile industry was investigated in this study. The halophilic prokaryotes isolated from a solar sea‐saltern (Çamalt?) in Turkey were screened for resistance to five commercial azo and mixture of azo‐metal complex dyes. Only one bacterium was found to be resistant against two of dyes, namely Lanaset Navy R and Lanaset Brown B. The bacterium was identified as Halobacillus sp. C‐22 according to 16S rRNA gene sequence analyses. Decolorization experiments were carried out at 120 mg/L concentration of both dyes, at room temperature, and with an acidic pH of 4.5. Lanaset Brown B was decolorized at a high adsorbance ratio (96.12%) at the 78th hour. However, Lanaset Navy R was rapidly decolorized in 10 min (46.67%) and showed the highest adsorbance ratio (60.66%) at the third hour. Freundlich and Langmuir equilibrium isotherm models were used to evaluate the adsorption of dyes and Freundlich isoterm was more suitable for biosorpsiyon of both azo dyes. The functional groups on Halobacillus sp. C‐22 for decolorization were characterized by FT‐IR. This is the first study to reveal potential of Halobacillus sp. for decolorization of textile azo‐metal complex dyes.  相似文献   

2.
By‐products of various industrial fermentations can be good adsorbents for removing hazardous dyes from wastewater. However, after biosorption, regeneration of biomass is essential to minimize the solid waste generation or else the dye laden biomass should be suitably disposed off. In the present work, experiments were conducted on the Acid Navy Blue and Methylene Blue dyes which were biosorbed to the fungal biomass (strain closely related to Aspergillus lentulus) produced on corncob as the substrate through solid state fermentation. In order to dispose the dye laden biomass, it was vermicomposted along with cow dung (CD) employing Eisenia fetida. Results indicated that the dye laden biomass was not lethal toward the earthworms as no mortality was observed. However, as compared with control experiments (where dye laden biomass was absent), the reproductive potential of the earthworms was affected. Nevertheless, further investigations on optimization of biomass and CD ratios can facilitate vermicomposting as a potential route for disposing dye laden biomass.  相似文献   

3.
Purification of Wastewaters Containing Azo Dyes This study describes the degradability of the azo dye C.I. Reactive Violet 5 by a continuous flow biological treatment system consisting of three rotating disc reactors. The azo dye was first decolorized in an anaerobic reactor. Decolorization was improved by adding an auxiliary substrate (yeast extract and acetic acid). Although severe operating conditions were experienced due to failures in the temperature and pH-controllers, the reactor recovered quickly and continued to decolorize reliably. The removal of the auxiliary substrate in the anaerobic reactor was not satisfactory, probably due to the copper in the azo dye. Batch experiments showed that copper was removed from the dye molecule and precipitated during the decolorization. In the continuous flow reactor, the copper precipitate on the disc can redissolve due to a pH-gradient in the fixed biomass becoming toxic again for the bacteria. In the following two aerobic reactors, the auxiliary substrate was degraded, but mineralization of the dye metabolites was insufficient. The aromatic amines produced by the anaerobic decolorization are more toxic in the bacterial luminescence test than the azo dye. Therefore, decolorization alone cannot be used to treat colored wastewater. Since the amines can also be produced in anaerobic parts of rivers, the dyes have to be removed in a more efficient way. That is the reason why in further experiments ozonation is being tested to increase the biological degradability of the azo dye for a following aerobic stage. Either ozonation can be used after the two stage treatment of the dye in anaerobic/aerobic reactors or the dye can be oxidized directly, making the addition of auxiliary substrate unnecessary. These configurations are being tested with the goal to degrade the dye with the least ozone consumption.  相似文献   

4.
A solid‐phase extraction (SPE)‐gas chromatography (GC)‐mass spectrometry (MS) analytical method was developed for the simultaneous analysis of natural free estrogens and their conjugates in wastewater samples. Natural free estrogens and their conjugates in wastewater were successfully separated by the oasis hydrophilic‐lipophilic balance solid phase extraction (Oasis HLB SPE) method, and the conjugates were initially enzyme hydrolyzed by β‐glucuronidase or arylsulfatase from Helix pomatia prior to derivatization. N‐methyl‐N‐(tert‐butyldimethylsilyl)trifluoroacetamide (MTBSTFA) plus 1% tert‐butyldimetheylchlorosilane (TBDMCS) was chosen as the derivatization reagent, and the most appropriate conditions of derivatization were determined to be at 95°C for 90 min. The recovery ratios of nine target chemicals were determined by spiking them in 1 L of ultra‐purified water or the influent of a wastewater treatment plant (WWTP). The recovery ratios of six out of nine for the analytes ranged from 73.3–114.9% with relative standard deviations (RSD) from 1.6–19.9%. The established method was successfully applied to environmental wastewater samples which were collected from one municipal wastewater treatment plant (WWTP) in Osaka, Japan, for the determination of natural free estrogens and their conjugates. In the influent sample, E1, E2, E1‐3S, E3‐3S, and E1‐3G were detected at concentrations of 16.6, 9.6, 8.2, 21.9, and 3.2 ng L–1, respectively. However, only E1 was detected at a high concentration of 44 ng L–1 in the effluent sample, suggesting that it is the dominant natural free estrogen in the effluent.  相似文献   

5.
Solar photocatalytic decolorization and detoxification of batik dye wastewater using titanium dioxide (TiO2) immobilized on poly‐3‐hydroxybutyrate (P(3HB)) film was studied. The effects of initial dye concentration, catalyst concentration, P(3HB) film thickness, and fabrication methods of the nanocomposite films were evaluated against methylene blue, a standard organic dye. It was observed that 0.4 g of P(3HB)‐40 wt% TiO2 removed 96% of the color under solar irradiation. P(3HB) and TiO2, mixed concurrently in chloroform followed by stirring for 24 h showed a more even distribution of the photocatalyst on the polymer surface and yielded almost 100% color removal. The photocatalytic films were able to completely decolorize real industrial batik dye wastewater in 3 h and induced a chemical oxygen demand (COD) reduction of 80%. Reusability of the 0.4 g P(3HB)‐40 wt% TiO2 film in decolorizing the batik dye wastewater was also possible as it gave a high consistent value of decolorization percentage (>80%) even after the sixth repeated usage. Recovery step of the photocatalysts was also not required in this simple treatment system. The decolorized batik dye wastewater had less/no toxic effects on mosquito larvae, Aedes aegypti, and microalgae, Scenedesmus quadricauda indicating simultaneous detoxification process along with the decolorization process.  相似文献   

6.
Due to the unique chemical properties and therefore wide range of applications, significant amounts of reactive dyes often end up in waste waters and this issue raises the need for more efficient treatment technologies. This work investigates the ability of magnetite nanoparticles functionalized with imidazolium based ionic liquid (IL) as an efficient sorbent for the removal of the Reactive black 5 from wastewater. Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, thermo‐gravimetric analysis, and zeta potential measurement were used to characterize the synthesized nanosorbent. The results showed that under optimal conditions, the dye removal efficiency of the grafted IL is 98.5% after a single run. Regeneration of the used sorbent could be possible and the modified magnetic nanoparticles exhibited good reusability. The isothermal data of RB5 sorption conformed well to the Langmuir model and the maximum sorption capacity of IL@Fe3O4 for RB5 was 161.29 mg g?1. Thermodynamic study indicated that the adsorption is endothermic and spontaneous. The use of such a system can provide fast and efficient removal of the reactive dyes from wastewater by using an external magnetic field.  相似文献   

7.
The classical aim of the application of super absorbent polyacrylate (SAPs) hydrogels is the prolonging of plant survival under water stress. Their effect on plant growth during non‐water stress conditions is not known. This study examined the root and shoot biomass of seedlings of nine tree species; Eucalyptus grandis, Eucalyptus citriodora, Pinus caribaea, Araucaria cunninghamii, Melia volkensii, Grevillea robusta, Azadirachta indica, Maesopsis eminii and Terminalia superba. The seedlings were potted in five soil types; sand, sandy loam, loam, silt loam and clay. These were amended at two hydrogel levels: 0.2 and 0.4% w/w and grown under controlled conditions in a green house. Root and shoot growth responses of the seedlings were determined by measuring the dry weight of the roots, stems, leaves and twigs. The addition of either 0.2 or 0.4% hydrogel to the five soil types resulted in a significant increase of the root dry weight (p < 0.001) in eight tree species compared to the controls after 8 wk of routine watering. Also, the dry weight of stems and leaves and twigs were significantly (p < 0.001) higher in the nine tree species potted in hydrogel amended soil types than in the hydrogel free controls. These results suggested that hydrogel amendment enhances the efficiency of water uptake and utilization of photosynthates of plants grown in soils which have water contents close to field capacity.  相似文献   

8.
In the present study, Oreganum onites L. stalks in natural and chemically modified with HNO3 and H3PO4 used as adsorbent for removal of both acidic and basic dyes from waters. The adsorption was studied as a function of pH and contact time by batch method. All tested biosorbents were characterized by FT‐IR, scanning electron microscopy, and measuring the pH dependence of the zeta potential. The adsorption isotherms were fitted to Langmuir isotherm. The maximum adsorption capacity of dyes was 280.73 mg g?1 for Basic Red 18, 147.06 mg g?1 for methylene blue and 112.36 for Acid Red 111, which is comparable to that of other lignocellulosic materials. The modification process was considerably increased the biosorption capacity of lignocellulosic material, resulting in a 56–63% increase in the biosorption capacity of basic dyes and a 125% increase in the biosorption capacity of acidic dye. The present study illustrated that the most effective factors in the adsorption of basic dye were surface charge and acidic groups on lignocellulosic biosorbents, while non‐electrostatic forces as well as electrostatic forces were also effective in the adsorption of acidic dye. In conclusion, Oreganum stalks can be considered as a very prospective adsorbent for the removal of tested basic and acidic dyes.  相似文献   

9.
A novel, simple, fast, and efficient ionic liquid‐based dispersive liquid–liquid extraction (IL‐DLLE) has been applied to extract and remove Congo Red (CR; a carcinogenic textile dye) from aqueous solutions. In this methodology a binary solution, containing the extraction solvent (1‐hexyl‐3‐methylimmidazolium bis(trifluormethylsulfonyl) imid) and a suitable disperser solvent, was rapidly injected into the water sample containing CR dye. Therewith, a cloudy solution was formed, and most of the dye molecules were extracted into fine IL droplets and removed from aqueous phase. The effects of pH, type, and amount of IL, initial concentration of the dye, type and volume of the dispersant, and concentrations of salt on the extraction of the dye were studied. Experimental surveys were also accomplished for recovery of the IL by applying a reverse dispersive liquid–liquid extraction using acidic stripping solutions.  相似文献   

10.
Bacillus subtilis and its extracellular polysaccharide (EPS) were used in free form as well as immobilized form as biosorbent for the removal of an anionic dye Procion Red MX 5B. Low pH was favourable for biosorption. Immobilization resulted in reduced biosorption of the dye. The presence of functional groups responsible for the high adsorption capacity in free cells (FC) and EPS was confirmed by FTIR analysis. High Qmax and b values were noted in the case of FC and free EPS in contrast to immobilized cells and EPS. The kinetics data showed that the adsorption system followed pseudo‐first‐order reaction at low dye concentration. Desorption of the dye was found to be 100% in 1 N NaOH. In the case of immobilized biomass and EPS the alginate was found to be unstable under high alkaline conditions of NaOH.  相似文献   

11.
Field Treatment of MTBE‐Contaminated Groundwater Using Ozone/UV Oxidation   总被引：1，自引：0，他引：1  
Methyl‐tertiary butyl ether (MTBE) is often found in groundwater as a result of gasoline spills and leaking underground storage tanks. An extrapolation of occurrence data in 2008 estimated at least one detection of MTBE in approximately 165 small and large public water systems serving 896,000 people nationally (United States Environmental Protection Agency [U.S. EPA] 2008). The objective of this collaborative field study was to evaluate a small groundwater treatment system to determine the effectiveness of ultraviolet (UV)/ozone treatment in removing MTBE from contaminated drinking water wells. A pilot‐scale advanced oxidation process (AOP) system was tested to evaluate the oxidation efficiency of MTBE and intermediates under field conditions. This system used ozone as an oxidizer in the presence of UV light at hydraulic retention times varying from 1 to 3 min. MTBE removal efficiencies approaching 97% were possible with this system, even with low retention times. The intermediate t‐butyl alcohol (TBA) was removed to a lesser extent (71%) under the same test conditions. The main intermediate formed in the oxidation process of the contaminated groundwater in these studies was acetone. The concentrations of the other anticipated intermediates t‐butyl formate (TBF), isopropyl alcohol (IPA), methyl acetate (MAc), and possible co‐occurring aromatics (BTEX) in the effluent were negligible.  相似文献   

12.
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13.
The sorption of reactive (textile) dyes onto cucurbituril, a cyclic polymer with hydrophobic cavity, was studied. Dye sorption is strongly enhanced by Ca2+ or Sr2+ concentrations up to 100 mmol/L for all studied dyes. Mg2+ and alkaline ions had similar effects for only one dye (Reactive Red 120), and only at higher concentrations. Concentrations above 100 mmol/L – depending on cation and dye – dissolve cucurbituril and prevent dye removal. As shown in previous studies by our group loadings obtained under suitable conditions (calcium concentration between 2 and 100 mmol/L, total salt concentration not exceeding 100 mmol/L) are 1 to 1.7 mol/mol or 0.9 to 1.8 g/g. The chemical mechanism responsible for the ionic influences is still under investigation. Generally, cucurbituril is a potent sorbent for reactive dyes. However, the technical application is still limited by the lack of a support material that would allow use in fixed bed filters.  相似文献   

14.
Ten Indian mustard (Brassica juncea L.) genotypes were screened for their phytoremediation potential for arsenic (As) contaminated water under laboratory‐controlled conditions. The genotypes were grown in a hydroponic chamber for 20 days in 250‐mL beakers containing As‐contaminated water. During plant development, changes in plant growth, biomass, and total As were evaluated. Of the 10 genotypes (Pusa Agrani, BTO, Pusa Kranti, Pusa Bahar, Pusa Bold, Pusa Basant, Pusa Jai Kisan, Arka Vardhan, Varuna, and Vaibhav) Pusa Jai Kisan was the most effective in phytoremediating As‐contaminated water under hydroponic conditions. This will provide new information for Indian mustard genotypes for phytoremediating As‐contaminated soils.  相似文献   

15.
Karst aquifers are susceptible to contamination by microorganisms, but relatively few studies have used bacteria as tracers. We demonstrate the utility of Escherichia coli enriched in the stable isotope nitrogen‐15 (15N) as a novel bacterial tracer. Nonpathogenic E. coli from two springs in central Kentucky were grown on 15N‐enriched media. Survival of E. coli and persistence of the isotopic signal were assessed in two sets of laboratory experiments conducted with sterilized spring water in dark microcosms at 14 °C. First, isotopically labeled bacteria survived for 130 d at concentrations within one log unit of the average initial value, and there was no significant difference in δ15N values from Day 1 to Day 130. Second, water samples with E. coli were inoculated with either of two different species of protozoa (Tetrahymena pyriformis or Colpoda steinii). During 7 d, δ15N values increased in T. pyriformis while bacterial populations decreased. In a field test, following a 2.1‐cm rainfall, 15N‐labeled E. coli, solutes (rhodamine WT dye and bromide), and latex microspheres were injected into a sinkhole approximately 530 m upgradient of a spring. Breakthrough of all tracers coincided, but microspheres were remobilized by subsequent storms, unlike other tracers. Enriched E. coli exhibited more tailing than solute tracers during the initial storm‐flow recession. These results indicate that 15N‐enriched E. coli is a viable tracer of bacterial transport in karst aquifers, although predation may attenuate the isotopic signal in systems that are not rapidly flushed.  相似文献   

16.
Photooxidation degradation of Reactive Brilliant Red K‐2BP (K‐2BP) aqueous solution by ultraviolet irradiation/sodium hypochlorite (UV/NaClO) was investigated. The effects of NaClO dosage, pH, temperature and initial dye concentrations were studied. A possible degradation pathway of K‐2BP was investigated. Acidic or neutral conditions were beneficial to the decolorization of K‐2BP aqueous solution. However, alkaline conditions facilitated chemical oxygen demand (COD) removal. Increasing the solution temperature from 20 to 50°C increased the removal of color and COD. However, at 60°C, the final percentage color and COD removal decreased by approximately 17 and 10%, respectively. Based on the products indentified and theoretical analysis, N=N cleavage and C‐N cleavage were possible initial steps in the degradation of K‐2BP. From the results of this work, we conclude that treatment of UV/NaClO is an efficient method to degrade K‐2BP in aqueous solution.  相似文献   

17.
There are many fundamental problems with the injection of nano‐zero‐valent iron (NZVI) particles to create permeable reactive barrier (PRB) treatment zone. Among them the loss of medium porosity or pore blocking over time can be considered which leads to reduction of permeability and bypass of the flow and contaminant plume up‐gradient of the PRB. Present study provides a solution for such problems by confining the target zone for injection to the gate in a funnel‐and‐gate configuration. A laboratory‐scale experimental setup is used in this work. In the designed PRB gate, no additional material from porous media exists. NZVI (d50 = 52 ± 5 nm) particles are synthesized in water mixed with ethanol solvent system. A steady‐state condition is considered for the design of PRB size based on the concept of required contact time to obtain optimum width of PRB gate. Batch experiment is carried out and the results are used in the design of PRB gate width (~50 mm). Effect of high initial NO3–‐N concentration, NZVI concentration, and pore velocity of water in the range of laminar groundwater flow through porous media are evaluated on nitrate‐N reduction in PRB system. Results of PRB indicate that increasing the initial NO3–‐N concentration and pore velocity has inhibitor effect—against the effect of NZVI concentration—on the process of NO3–‐N removal. Settlement velocity (S.V.) of injected NZVI with different concentrations in the PRB is also investigated. Results indicate that the proposed PRB can solve the low permeability of medium in down‐gradient but increasing of the S.V. especially at higher concentration is one of the problems with this system that needs further investigations.  相似文献   

18.
This study investigates structural and adsorption properties of the powdered waste shells of Rapana gastropod and their use as a new cheap adsorbent to remove reactive dye Brilliant Red HE‐3B from aqueous solutions under batch conditions. For the powder shells characterization, solubility tests in acidic solutions and X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), Fourier transform IR spectroscopy (FT‐IR) and thermogravimetric analyses were performed. The results revealed that the adsorbent surface is heterogeneous consisting mainly from calcium carbonate layers (either calcite or aragonite) and a small amount of organic macromolecules (proteins and polysaccharides). The dye adsorptive potential of gastropod shells powder was evaluated as function of initial solution pH (1–5), adsorbent dose (6–40 g L?1), dye concentration (50–300 mg L?1), temperature (5–60°C), and contact time (0–24 h). It was observed that the maximum values of dye percentage removal were obtained at the initial pH of solution 1.2, shells dose of 40 g L?1, dye initial concentration of 50–50 mg L?1 and higher temperatures; the equilibrium time decreases with increasing of dye concentration. It is proved that the waste seashell powder can be used as low cost bioinorganic adsorbent for dyes removal from textile wastewaters.  相似文献   

19.
A Na‐montmorillonite membrane wastewater renovation prototype system was developed to specifically treat an ionic azo dye. Efficiency of this prototype system was limited to membrane fouling. Fouling rates were not consistently uniform owing to steric effects and competition for exchange sites. The decrease in solute rejection with time can be attributed to the decrease in the relative permeability of the compacted Na‐montmorillonite membrane to the dye with time due to fouling. This decrease occurs probably as a two‐step nucleation–growth mechanism with the nucleation part dependent in part on solvent flux, number of nucleation sites on the membrane, and sorbed mass part that controls solute flux and organic polymerization. The effect of concentration polarization was significant since the flux was higher than the mass‐transfer coefficient. The low diffusion coefficient of the ionic azo dye resulted in low mass transfer coefficients. The most important macromolecular solution properties to be considered for pilot systems may include high concentration‐dependent viscosity, possible non‐Newtonian fluid behavior, and low and concentration‐dependent self‐diffusivity amongst other factors. For pilot systems, the greater the quantity of large macromolecules in the ambient water, the greater the necessity of reducing the permselectivity of the membrane to prevent significant polarization.  相似文献   

20.
Batch sorption technique was carried out for the removal of anionic dye Congo red (CR) from aqueous solution using raw rectorite (R‐REC) and organified rectorite (CTA+‐REC) modified by cetyltrimethylammonium bromide (CTAB) as adsorbents. The effects of organification degree of CTA+‐REC as well as the process parameters including the pH of dye solution, sorption time, and initial dye concentration on adsorption capacity for CR were investigated and the sorption kinetics was also evaluated. The results showed that the sorption behaviors of R‐REC and CTA+‐REC for CR followed pseudo‐second‐order kinetic model and the sorption equilibrium data perfectly obeyed the Langmuir isotherm. The thermodynamic parameters including entropy of sorption (ΔS0), enthalpy of sorption (ΔH0), and Gibbs free energy of sorption (ΔG0) were obtained and analyzed. Fourier transform infrared study revealed that a chemisorption process occurred between CR and CTA+‐REC. REC modified by cationic surfactants showed the higher adsorption capacities for CR compared to R‐REC and in theory would be used as an efficient and promising adsorbent for the removal of anionic dyes in wastewater treatment.  相似文献   

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