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1.
Adsorption kinetic and equilibrium studies of two reactive dyes, namely, Reactive Red 31 and Reactive Red 2 were conducted. The equilibrium studies were conducted for various operational parameters such as initial dye concentration, pH, agitation speed, adsorbent dosage and temperature. The initial dye concentration was varied from 10 - 60 mg/L, pH from 2–11, agitation speed from 100–140 rpm, adsorbent dosage from 0.5 g to 2.5 g and temperature from 30 °C -50 °C respectively. The activated carbon of particle size 600 μm was developed from preliminary tannery sludge. The dye removal capacity of the two reactive red dyes decreased with increasing pH. The zero point charge for the sludge carbon was 9.0 and 7.0 for the two dyes, respectively. Batch kinetic data investigations on the removal of reactive dyes using tannery sludge activated carbon have been well described by the lagergren plots. It was suggested that the Pseudo second order adsorption mechanism was predominant for the sorption of the reactive dyes onto the tannery sludge based carbon. Thus, the adsorption phenomenon was suggested as a chemical process. The adsorption data fitted well with Langmuir model than the Freundlich model. The maximum adsorption capacity(q0) from Langmuir isotherm were found to have increased in the range of 23.15–39.37 mg/g and 47.62–55.87 mg/g for reactive dyes reactive red 31 and reactive red 2, respectively.  相似文献   

2.
Nanofiltration of ternary mixtures of sodium chloride and aqueous solutions of Reactive Black-5 was studied in two different modules, namely, flat sheet and spiral wound over a wide range of operating conditions. Hydrophilized polyamide membrane with molecular weight cutoff of 150 was used for the experiments. Combined effect of dye and salt concentration, trans-membrane pressure drop, initial pH of feed solution on the permeate flux, and observed retention were investigated. Extent of color removal, chemical oxygen demand (COD), total dissolved solid (TDS), and conductivity were determined to assess performance of the membrane. The experimental results showed that both the permeate flux and observed retention decreased with increase in dye as well as salt concentration in the feed. Permeate fluxes were lower at higher pH values. Substantial removal of color was achieved in the nanofiltration experiments with a marked reduction in COD and TDS. The process allowed the production of permeate stream with great reutilization possibilities.  相似文献   

3.
In this laboratory pilot-scale study, a hybrid treatment system has been developed to remove chlorinated solvent trichloroethylene and fine particles from chlorinated solvent trichloroethylene-contaminated groundwater before it is applied for further recovery. The two-stage system contained fiber-ball filtration followed by nanofiltration membrane processes. The measured chlorinated solvent trichloroethylene and suspended solids of the tested groundwater were 850 μg/L and 1,052 mg/L, respectively. Up to 97.3 % of chlorinated solvent trichloroethylene and 99.9 % of SS could be removed by the hybrid system with an operational pressure of 4.1 kg/cm2. The chlorinated solvent trichloroethylene removal mechanism in the fiber-ball filtration process could be due to adsorption. Approximately 98.2 and 78.6 % of chlorinated solvent trichloroethylene rejection was observed when nanofiltration membrane was used for chlorinated solvent trichloroethylene removal with the recover rate of 80 % and initial chlorinated solvent trichloroethylene concentration of 1 and 10 mg/L. Higher chlorinated solvent trichloroethylene rejection can be obtained when lower chlorinated solvent trichloroethylene concentration (1 mg/L) was applied. High chlorinated solvent trichloroethylene concentration (10 mg/L) would increase the pore size of nanofiltration, which causes the decrease in chlorinated solvent trichloroethylene rejection rate. Approximately 46.6 % of flux drop was observed when nanofiltration membrane was used along compared to the system using FF as the first treatment stage. This indicates that the application of fiber-ball filtration could maintain a higher flux of groundwater treatment. The developed fiber-ball filtration and nanofiltration hybrid membrane system is able to reduce the chlorinated solvent trichloroethylene and solid concentrations to meet the water reuse and groundwater remediation standards.  相似文献   

4.
The adsorption behavior of four anionic dyes and one disperse dye in single solution and binary solutions on fly ash was investigated in order to elucidate the effect of competitive adsorption on the kinetics. The experimental findings showed that adsorption equilibriums of four anionic dyes were reached within 50 min either in the single solution or in binary mixtures. Competitive adsorption increased the time of attaining equilibrium of disperse dye. Desorption of dyes suggested the predominant adsorption mechanisms, that is, chemisorption for anionic dyes and physisorption for disperse dye. For the binary mixtures, the anionic dyes could be adsorbed preferentially on fly ash at the first stage. Second-order kinetic models fitted better to the equilibrium data of all dyes in the single solution as well as in the binary mixtures. The maximum rate constant of intraparticle diffusion and the minimum external mass transfer coefficient was found for disperse dye both in single and in binary solutions. The intraparticle diffusion constants and external mass transfer coefficients of the four anionic dyes in binary solution are similar to those obtained in single solution. The Biot number confirmed that the intraparticle diffusion was the rate-limiting step in the dye sorption process.  相似文献   

5.
Contamination of surface water and groundwater by organic pollutants is a serious problem due to their persistence, bioaccumulation and biomagnification through food webs. Since the removal of dyes from wastewater is considered an environmental challenge and government legislation requires textile wastewater to be treated, therefore there is a constant need to have an effective process that can efficiently remove these dyes. The aim of the present study is to evaluate the potentiality of dried Carpobrotus edulis plant as low-cost adsorbent for the removal of the industrial acid blue 113 dye from aqueous solutions using the batch equilibration technique. The effects of different physicochemical parameters such as adsorbent dose, contact time, initial dye concentration, solution pH and temperature on adsorption rate of anionic AB113 dye on microparticles of dried C. edulis plant were investigated. The experimental data were analyzed by using mathematical models to determine the thermodynamic parameters. The negative values of free energy change indicated the spontaneous nature of the adsorption and negative value of enthalpy change suggested the exothermic nature of the adsorption process. These results indicate that dried C. edulis plant as an environmentally friendly adsorbent could be potentially used for the removal of anionic dyes from aqueous solutions.  相似文献   

6.
Adsorption of disperse dyes from aqueous solutions onto calcined alunite has been investigated to assess the possibility of using alunite for removing disperse dyes from aqueous solutions. The effects of particle size, adsorbent mass, initial pH and temperature of the dye solution on the adsorption capacities have been evaluated. Acidic pH was favorable for the adsorption of all dyes: Disperse Blue 56 (DB56), Disperse Red 74 (DR74) and Disperse Yellow 119 (DY119). The experimental data were correlated reasonably well by the Langmuir isotherm and the isotherm parameters (KL and aL) have been calculated. The adsorption capacities were found to be 498, 525 and 500 mg of dye per g of calcined alunite for DB56, DR74 and DY119, respectively. The single-stage batch adsorber design of the adsorption of disperse dyes onto alunite has been studied based on the Langmuir isotherm equation.  相似文献   

7.
Peat of Brunei Darussalam shows a great potential for the removal of methylene blue (MB) and malachite green (MG) dyes from aqueous solution. Carefully controlled batch experiments performed by changing one parameter at a time indicate that the optimum time periods of agitation and settling required for maximum removal of MB are 2.0 and 1.0 h, respectively, while these values for MG are 4.0 and 1.0 h, respectively. The optimum pH is determined to be the ambient value, and under the optimum conditions, 90 % removal of both dyes was determined under laboratory conditions. The equilibrium adsorption data analyzed for various isotherm models suggest that the Sips and Redlich–Peterson (R–P) models are valid for MB and MG, respectively. Further, thermodynamic studies show that the adsorption of both dyes on peat is spontaneous and endothermic. The adsorption capacities (q max) of MB and MG dyes on peat are 0.45 and 0.31 mmol g?1, respectively. Characterization of the surfaces of peat before and after treatment of dyes by SEM and FTIR provides conclusive evidence of adsorption of both dyes. Kinetics studies indicate that the adsorption of both MB and MG dyes is favored toward the pseudo-second-order model, with a little contribution of MG to the pseudo-first-order model. These results suggest that peat is a potential low-cost adsorbent for the removal of MB and MG dyes.  相似文献   

8.
Different parameters were investigated to evaluate their effect on the process removal efficiency of reactive dye from simulated spent reactive dye bath, by solar / TiO2 / H2O2, including H2O2 concentration, TiO2 loading and pH. As a result 99% of reactive dye can be removed at a TiO2 loading of 400mg/l, H2O2 concentration of 150 mg/l and of pH: 5.2. The effect of photo-catalytic deactivation of TiO2 on reactive dye removal was studied for ten number of cycles, and found that the extent of deactivation was high for each consecutive repeated use.  相似文献   

9.
Environmental contamination resulting from dyes has become a serious concern for today’s world. The textile effluents are highly colored, and the disposal of these in water bodies causes severe damage to the environment by reducing the solar light penetration which may affect the photosynthetic activity and the aquatic life in water. Further, the high water solubility of dyes also leads to surface and ground water contamination. Thus, in this study, we attempt to develop a cost-effective and eco-friendly method for removal of toxic dyes from aqueous using biosynthesized iron nanoparticles (INPs). Various complimentary instruments such as a thermogravimetric analysis, scanning electron microscopy/energy dispersive X-ray spectrometer, and X-ray diffraction were employed for identification and characterization of INPs. The biosynthesized INPs were applied as a Fenton-like catalyst for decolorization of toxic dyes solution like methylene blue, methyl orange, allura red, brilliant blue, and green S using hydrogen peroxide under solar radiation. The decolorization of the toxic dyes solution using INPs was monitored by UV–visible spectrophotometer, and the data obtained were utilized to evaluate the kinetic rate of the reactions. The kinetic data suggest that the decolorization of all studied toxic dyes solution follows first-order rate with rate constant values in the range of 13.1 × 10?3–17.7 × 10?3 min?1. Therefore, such a clean method employing non-toxic plant extract in INP synthesis and the application of INPs as a Fenton-like catalyst in toxic dyes decolorization can be considered as an alternative technique to the expensive and toxic chemical methods.  相似文献   

10.
In the present study, a widely used reactive dye, Color Index (C.I.) Reactive Blue 268 was utilized for mycoremediation by Aspergillus fumigatus isolated from textile effluent. Complete decolorization of the test dye (0.1 g L?1) was recorded within 6 days of static incubation at 27 °C in Czapek Dox broth (CDB). However, the isolate was unable to utilize the dye as a sole source of energy in Czapek Dox agar and CDB in absence of sucrose and obligate requirement of a labile carbon source, i.e., sucrose needed for induction of decolorization. Biosorption seems to play the pivotal role in decolorization as evident by coloring of the fungal biomass as that of dye color. The optimal conditions for the highest decolorization were found at 30 °C and pH 6.0 with 6-day-old inoculums supplemented with sucrose (10 g L?1) and ammonium chloride (2 g L?1) as a carbon and nitrogen source, respectively. The response of the isolate to increasing dye concentrations was found to be growth inhibitory. Surprisingly, about 65 % of dye decolorization was recorded with heat-inactivated biomass powder within 6 days of static incubation supporting the fact of fungal biosorption. Results of this study have established the candidature of the isolate for biotechnological removal of dyes from disreputable dying effluents.  相似文献   

11.
Exhausted Reactive dye bath samples of Turquoise Blue, Olive Green and Navy Blue shades were collected from cotton knit wear dyeing units in Tirupur. Ozonation was conducted in a column reactor system fed with ozone at the rate of 0.16 g/min to assess its efficiency in reducing the color, chemical oxygen demand and total organic carbon. Complete decolorization of the effluent was achieved in 10 min contact time and ozone consumption of 153 mg/ L for Turquoise Blue, 128 for Olive Green and 143 for Navy Blue shades effluents respectively. The corresponding COD removal was 43%, 44% and 43% for the three shades while TOC removal efficiency was 45%, 45% and 40% respectively. The results from the reusability studies indicate that the dyeing quality was not affected by the reuse of decolorized dye bath for two successive cycles. It is concluded that ozonation is efficient in decolorization of exhausted dye bath effluents containing conventional reactive dyes. However, the corresponding removal of COD from the textile effluent was not significant.  相似文献   

12.
Detoxification of synthetic dyes is one of the main challenges in clearing textile industry wastes. Biodegradation of azo-dyes using Phanerochaete chrysosporium is one the most environmentally friendly methods available. The main enzymes responsible for mycodecolorization process are lignin and manganese peroxidases. Here, optimization of expression conditions has been carried out with manipulating culture condition and nutrient sources. Therefore, the effects of buffer and temperature as well as nitrogen source on lignin peroxidase and manganese peroxidase production were investigated at two levels and four levels, respectively. For this purpose, P. chrysosporium RP78 based on Taguchi design of experiment has been applied. Maximum lignin and manganese peroxidase activities of 182 ± 2.5 U/L and 850 ± 41 U/L were obtained under predicted optimum conditions, respectively. Thereby, about 100 % decolorization was achieved after 24 h for two most widely used groups of azo dyes in textile industry consisting reactive and acidic. The physical adsorption of the azo dyes by mycelia was not significant which indicated that the enzymatic degradation of the dyes was occurred. Time profile of these enzymes showed that manganese peroxidase was peaked on 9th day while lignin peroxidase peaked on 13th day and remained stable in the culture. The extracellular expression profiles of both were studied by 2 dimensional gel electrophoresis to partially characterize the enzymes.  相似文献   

13.
Removal of dyes by low-cost adsorbents is an effective method in wastewater treatment. Iranian natural clays were determined to be effective adsorbents for removal of a basic dye (methylene blue) from aqueous solutions in batch processes. Characterizations of the clays were carried out by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis and field-emission scanning electron microscopy. Effects of the operational parameters such as adsorbent dosage, initial dye concentration, solution pH and temperature were investigated on the adsorption performance. Adsorption isotherms like Langmuir, Freundlich and Temkin were used to analyze the adsorption equilibrium data and Langmuir isotherm was the best fit. Adsorption kinetics was investigated by pseudo-first-order, pseudo-second-order and intraparticle diffusion models and the results showed that the adsorption system conforms well to the pseudo-second-order model. The thermodynamic parameters of adsorption (ΔS°, ΔH° and ΔG°) were obtained and showed that the adsorption processes were exothermic.  相似文献   

14.
Benthic fluxes of soluble reactive phosphorus (SRP) and dissolved inorganic carbon (DIC) were measured in situ using autonomous landers in the Gulf of Finland in the Baltic Sea, on four expeditions between 2002 and 2005. These measurements together with model estimates of bottom water oxygen conditions were used to compute the magnitude of the yearly integrated benthic SRP flux (also called internal phosphorus load). The yearly integrated benthic SRP flux was found to be almost 10 times larger than the external (river and land sources) phosphorus load. The average SRP flux was 1.25?±?0.56?mmol?m?2?d?1 on anoxic bottoms, and ?0.01?±?0.08?mmol?m?2?d?1 on oxic bottoms. The bottom water oxygen conditions determined whether the SRP flux was in a high or low regime, and degradation of organic matter (as estimated from benthic DIC fluxes) correlated positively with SRP fluxes on anoxic bottoms. From this correlation, we estimated a potential increase in phosphorus flux of 0.69?±?0.26?mmol?m?2?d?1 from presently oxic bottoms, if they would turn anoxic. An almost full annual data set of in situ bottom water oxygen measurements showed high variability of oxygen concentration. Because of this, an estimate of the time which the sediments were exposed to oxygenated overlying bottom water was computed using a coupled thermohydrodynamic ocean?Csea and ecosystem model. Total phosphorus burial rates were calculated from vertical profiles of total phosphorus in sediment and sediment accumulation rates. Recycling and burial efficiencies for phosphorus of 97 and 3%, respectively, were estimated for anoxic accumulation bottoms from a benthic mass balance, which was based on the measured effluxes and burial rates.  相似文献   

15.
A nanomembrane-based hybrid treatment system for separation of fluoride from contaminated groundwater and its subsequent stabilization in a solid matrix through chemical coagulation–precipitation process using response surface optimization for safe disposal were designed and investigated. The continuous flat-sheet cross-flow nanofiltration membrane module with well-screened commercial polyamide composite membrane succeeded in removing 99 % fluoride from water while yielding a pure water flux as high as 158–160 L/m2h of a transmembrane hydraulic pressure of only 14 bars. Such an operating pressure is much lower than that required in reverse osmosis for the same separation. The designed system for the first time provides a total solution to a complex problem in a very simple, compact, flexible, and novel design that ensures continuous, steady, and hassle-free long-term operation without the necessity for frequent replacement of membranes. The approximate cost for production of 1000 L of safe drinking water from fluoride-contaminated groundwater computes to only $ 1.4, indicating affordability in adopting the low-cost, high-flux water purification system by the affected people in many parts of the world.  相似文献   

16.
The ability of magnetically modified activated sludge affected by thermal treatment to remove water-soluble organic dyes was examined. Twelve different dyes were tested. Based on the results of the initial sorption study, four dyes (namely aniline blue, Nile blue, Bismarck brown Y and safranin O) were chosen for further experiments due to their promising binding onto magnetic activated sludge. Significant factors influencing adsorption efficiency such as dependence of contact time, initial pH or temperature were studied in detail. The adsorption process was very fast; more than 88 % of dye content (55 mg/L) was adsorbed within 15 min under experimental conditions used. The equilibrium adsorption data were analyzed by Freundlich, Langmuir and Sips adsorption isotherm models, and the fitting of each isotherm model to experimental data was assessed on the basis of error functions. The maximum adsorption capacities of magnetic activated sludge were 768.2, 246.9, 515.1 and 326.8 mg/g for aniline blue, Bismarck brown Y, Nile blue and safranin O, respectively. The kinetic studies indicated that adsorption of all selected dyes could be well described by the pseudo-second-order kinetic model, and the thermodynamic data suggested the spontaneous and endothermic process.  相似文献   

17.
Metal-complex dyes are widely used in textile industry, but harmful to the environment and human health due to aromatic structure and heavy metal ions. The objective of this work was to evaluate the adsorption potential of bamboo biochar for the removal of metal-complex dye acid black 172 from solutions. Freundlich model was more suitable for the adsorption process of bamboo biochar than Langmuir isotherm, indicating multilayer adsorption of acid black 172 on a heterogeneous bamboo biochar surface. Adsorption kinetics analysis of pseudo-second-order and Weber–Morris models revealed that intraparticle transport was not the only rate-limiting step. The bamboo biochar exhibited a good adsorption performance even at high ionic strength. Analysis based on the artificial neural network indicated that the temperature with a relative importance of 29 % appeared to be the most influential parameter in the adsorption process for dye removal, followed by time, ionic strength, pH and dye concentration.  相似文献   

18.
采用自制的中空纤维膜蒸馏组件对模拟的乳化油废水进行膜蒸馏处理研究, 分析了料液的浓度、流速、温度和处理时间等因素对膜通量及去除率的影响。实验结果表明: 在料液温度为50℃、流速为14 mL /min、乳化油浓度为500 mg/L 的条件下, 运行1 h后乳化油膜通量为21.20 g/m2 ·h, 去除率> 70%; 运行5 h后膜通量下降为5.141 g/m2 ·h, 去除率> 90%。  相似文献   

19.
Theoretical diffusive flux rates for dissolved reactive phosphate (DRP) were determined for sediments in a small area of the Indian River, Florida for the period March–May 1982. Flux rates from the sediment varied from 29 to 70 × 10?6g per m2 per day in seagrass associated sediments to 3–25 × 10?6g per m2 per day for an area devoid of seagrass. Simultaneous measurements of groundwater seepage velocities indicated greater velocities in seagrass associated sediments (1.03 × 10?6m per sec) than an area devoid of grass (0.77 × 10?6m per sec). Measured seepage flux accounted for more than 99% of the combined estimated diffusive and seepage flux of DRP for nearshore seagrass sediments. Also noted was an apparent direct relationship between tidal height, DRP and seepage velocity in nearshore sediments (25 m from shore) which further demonstrates the importance of hydrogeologic variables to these areas.  相似文献   

20.
Pectin–cerium (IV) tungstate composite (Pc/CT) has been prepared by sol gel method at room temperature. The composite ion exchanger has been characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and Fourier infrared spectroscopy. The ion exchange capacity, pH titrations, thermal stability and distribution coefficient of composite ion exchanger were investigated. The Na+ ions exchange capacity of the Pc/CT has been observed higher (1.4 meq g?1) as compared to its inorganic counterpart (0.8 meq g?1). Pc/CT composite ion exchanger was thermally stable and retained about 60 % of its ion exchange capacity up to 400 °C. The distribution study has inferred more selective the Pc/CT for Zn2+ as compared to other metal ions. The adsorption efficiency of Pc/CT was tested for methylene blue removal dye from aqueous phase. The removal of dye followed pseudo-second-order kinetics.  相似文献   

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