Decolorization of disperse and reactive dye solutions using ferric chloride

The composition of wastewater from dyeing and textile processes is highly variable depending on the dyestuff type; typically it has a high chemical oxygen demand. This study examined the decolorization of some of the most commonly used disperse and reactive dyestuffs by destabilization using ferric chloride as a coagulant. Dye removal, distributions of zeta potential, concentration of suspended solids, changes of the SCOD/TCOD ratio and distributions of SV and SVI values were investigated in this work. Compared to reactive dyes, disperse dyes have lower solubility, higher suspended solids concentrations and lower SCOD/TCOD ratios. It was concluded that disperse dye solutions are more easily decolorized by chemical coagulation than reactive dye solutions.     

Studies on castor seed shell as a sorbent in basic dye contaminated wastewater remediation

The potentialities of castor seed shell (CSS), a waste agricultural by-product, in the remediation of water, contaminated with Methylene Blue (MB), a basic dye, were investigated in the present study. The CSS was ground and washed, thoroughly, to remove any water extractable constituents. The dried CSS was reground, sieved and used in series of agitated batch adsorption experiments. The experiments were conducted to assess the effect of two process variables i.e. initial MB concentration and CSS dosage on the sorption process. The equilibrium sorption isotherm was studied using the two widely used isotherm models (i.e. Freundlich and Langmuir isotherm models). The results from the isotherm studies showed that the process of sorption of MB occurred on a heterogeneous surface of the CSS. The sorption capacity of the CSS, as obtained from the Langmuir plot was 158 mg/g. The mass transfer property of the sorption process was studied using Lagergren pseudo-first-order and chemisorptions pseudo-secondorder kinetic models. The sorption process obeyed the pseudo-second-order kinetic model more than the pseudo-first order; hence the mechanism of the sorption process was analysed further using this kinetic model. The application of the intraparticle diffusion model to determine the rate limiting step showed that intraparticle diffusion is not the singular rate limiting step in the sorption of MB onto CSS. The role of chemisorptions in the mechanism of sorption was established by an empirical relationship between the pseudo-second-order rate constant, K, and the initial MB concentration. The results of this relationship showed that pseudo-second-order chemisorptions are important in the sorption process.     

Removal of textile dye from aqueous solution by electrochemical method

The use of adsorption and electrochemical treatment technologies for wastewater treatment has significantly increased in recent years. In the present study, carbon prepared from biomass waste can be used as electrode material in the electrochemical process is shown. Given that the electrode material is quite expensive, low-cost manufacturing is gaining more and more importance. Electroadsorption of textile dye (Burdem Orange II) by using activated carbon prepared from waste material, which is cherry stones, was investigated with the variation in the parameters of pH, initial dye concentration, solution flow rate, applied potential, and supporting electrolyte. The removal efficiency of textile dye up to 98% were achieved by electrochemical method.     

Removal of basic dyes from aqueous solutions using natural clay

Adsorption properties of natural clay (from Eski?ehir of Turkey) were investigated by depending on different adsorption conditions such as different initial dye concentrations and contact times. The chemical composition of the natural clay was analyzed by X-ray fluorescence spectrometry (XRF). The removal of basic dyes such as Nile Blue (NB) and Brilliant Cresyl Blue (BCB) from aqueous solutions using natural clay in this study was described. After the equilibrium adsorption time of 8 h, the adsorption capacities for NB and BCB reach about 25 mg/g and 42 mg/g, respectively. Lagergren kinetic equation was used to test the experimental data to examine the controlling mechanism of adsorption processes. Adsorption data of the BCB and NB onto natural clay were fitted well by the pseudo-first-order model. The adsorption isotherms data were correlated with the Freundlich equation and the Freundlich constants K_f (mg/g) and n (intensity of adsorption) were calculated. The r² (regression coefficients) values were 0.9835 and 0.9849 for NB and BCB, respectively. The adsorption capacities of natural clay for NB and BCB have the following order: BCB > NB.     

Adsorption studies of aqueous basic dye solutions using sepiolite

Sepiolite, low cost, locally available and natural mineral was studied as an adsorbent for the removal of Basic Astrazon yellow 7GL from aqueous solutions and batch contact tests. The kinetics of the adsorption process was tested for the pseudo-first order, pseudo-second order reaction and intra-particle diffusion models. The rate constants of adsorption for all these kinetic models were calculated. Good correlation coefficients were obtained for the pseudo-second order kinetic model. Langmuir, Freundlich and Dubinin-Radushkevich isotherm models were applied to the experimental equilibrium data by changing temperature. The isotherm constants were determined by using the linear regression of these models. The monolayer coverage capacities of sepiolite for basic dye were found to be in the range of 62.5-88.5 mg/g at different temperatures. Thermodynamic studies showed that the reaction for dye uptake by sepiolite is endothermic in nature. Based on the optimum parameters sepiolite was also used as adsorbent for raw wastewater treatment and found as efficient as dye color removal.     

Biosorption of a reactive textile dye from aqueous solutions utilizing an agro-waste

In the present study a low-cost waste biomass derived from canned food plant, was tested for its ability to remove reactive textile dye from aqueous solutions. The batch biosorption experiments were carried out at various pH, biosorbent dosage, contact time and temperature. Optimum decolorization was observed at pH 2.0 and 1.6 g dm^− 3 of biomass dosage within 20 min. The first-order and the pseudo-second-order kinetics were investigated for the biosorption system. The applicability of the Langmuir and Freundlich isotherm models was examined. The thermodynamic parameters for the biosorption were also calculated. The experimental results in this study indicated that this low-cost biomaterial was an attractive candidate for the removal of textile dye Reactive Red 198 (RR198) from aqueous solutions.     

Sorption of textile dye from aqueous solution by macroporous amino‐functionalized copolymer

Macroporous poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) (PGME) was synthesized by suspension copolymerization and functionalized with diethylene triamine (PGME‐deta). The effect of pH, contact time, and sorbent mass on sorption efficiency of initial and functionalized copolymer sample for removal of Acid Orange 10 dye from aqueous solutions was studied. No dye was sorbed by nonfunctionalized copolymer, indicating that sorption of Acid Orange 10 by PGME‐deta is specific, through amino groups. The isotherm data are best fitted by Langmuir model, indicating homogeneous distribution of active sites in PGME‐deta as well as monolayer sorption. Sorption kinetics study showed that the sorption of Acid Orange 10 by PGME‐deta obeys the pseudo‐second‐order kinetic model. It was shown that PGME‐deta selectively sorbs Acid Orange 10 from binary solution with Bezaktiv Rot reactive dye. The comparison of sorption characteristics of PGME‐deta with activated carbon showed that this functionalized copolymer might be used as an alternative sorbent for textile dyes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Decolorization of Brown Chitooligomers in Aqueous Solution by Ozonation

Brown chitooligomers were obtained by gamma irradiation. Decolorization of brown chitooligomers in aqueous solution by ozonation was investigated. It was found that ozone could decolorize the brown chitooligomers in aqueous solution. When the pH value was below 2.93, the ozone treatment could inhibit yellowing and browning of chitooligomers in aqueous solution. As a result, the chitooligomers were slightly depolymerized by ozonation. The characterization showed that the decolorization by ozonation did not lead to the significant modification of chemical structure of the chitooligomers.     

Neural network modeling of biotreatment of triphenylmethane dye solution by a green macroalgae

The potential of a green macroalgae Cladophora species was investigated as a viable biomaterial for biotreatment of Malachite Green (MG) solution. The effects of operational parameters such as temperature, pH, initial dye concentration, reaction time and amount of algae on biological decolorization efficiency were studied. Biotreatment of MG solution by live and dead algae was compared. The reusability and efficiency of the live algae in long-term repetitive operations were also examined. COD and FT-IR analysis revealed the ability of algal species in biological degradation of the dye. An artificial neural network (ANN) model was developed to predict the biotreatment of MG solution. The findings indicated that the ANN provided reasonable predictive performance (R² = 0.987). The influence of each parameter on the variable studied was assessed, and reaction time and initial pH were found to be the most significant factors, followed by temperature, initial dye concentration and amount of algae. Simulations based on the developed ANN model can estimate the behavior of the biological biotreatment process under different conditions.     

Decolorization of disperse and reactive dyes by continuous electrocoagulation process

The electrocoagulation process was developed to overcome the drawbacks of conventional wastewater treatment technologies. This process is very effective in removing organic pollutants including dyestuff wastewater and allows for the reduction of sludge generation. The purposes of this study were to investigate the effects of the operating parameters, such as current density, electrode number, electrolyte concentration, electrode gap, dyestuff concentration, pH of solution and inlet flow rate, on decolorization by continuous electrocoagulation. The dye removal efficiencies and reaction rate constants from the curves following the first-order relationship of electrocoagulation were calculated. In addition, from the points of power consumption, the effects of the operating parameters were also searched. Finally, the behaviors of decolorization according to dyestuff types, i.e., disperse dye and reactive dye, were also examined.     

The adsorption of dyes from aqueous solution using diatomite

Raw diatomite was calcined at 450 °C for dyes removal from aqueous solution. SEM and FTIR analysis show that the raw diatomite contains organic impurities, which are removed after the calcination. The impurities removal decreases the specific surface area and increases the average pore diameter of raw diatomite, while improves its adsorption capability of dyes. The adsorption isotherm and kinetics experiments of methylene blue onto calcined diatomite were then carried out to investigate the adsorption property. It shows that the adsorption capacity of methylene blue is about 50 mg/g. The adsorption isotherm was fitted by the Langmuir, Freundlich and Redlich-Peterson models, which reveals that the Redlich-Peterson isotherm is the best one. Two kinetic models, pseudo-first order and pseudo-second order, were rearranged for expediently investigating the adsortpion mechanisms. Fitting results show that the pseudo-first-order model is better in describing the adsorption process.     

Utilization of paper mill sludge for removal of cationic textile dyes from aqueous solutions

ABSTRACT

The present study is concerned usage of paper mill sludge (PMS) as an effective adsorbent to remove the two cationic character dyes (Basic Blue 3 [BB3] and Basic Yellow 28 [BY28]) from aqueous solutions. The surface morphology and some characteristics of PMS were determined by Fouirer Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Brunauer Emmett Teller (BET). The parameters affecting the process – temperature (10–55°C), adsorbent dose (0.5–10 g/l), initial pH (2–10 pH), initial concentration (50–250 mg/l) and contact time (0–24 h) – were examined in the batch adsorption experiments. Maximum adsorption capacities (q_max) of two dyes at 1 g/l dose and pH value of 7 were also calculated as 89.35 and 79.81, respectively. Adsorption phenomena of BB3 and BY28 cationic dyes onto PMS is controlled by pseudo-second-order model. Thereafter, equilibrium experimental data were applied to Langmuir, Freundlich and Dubinin–Redushkevich (D-R) isotherms, and Langmuir isotherm is the best represent the equilibrium adsorption process for both dyes. The processes occurred by physical adsorption because of calculated activation values (E_a) of BB3 and BY28 dyes were 19.43 and 9.35 kJ/mol, respectively. In addition, based on thermodynamic calculations such as free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°), the results clearly demonstrated that the adsorption process were of exothermic and spontaneous nature for both dyes. At the light of obtained findings, it can be stated that PMS can be used effectively in removal of cationic dyes from textile wastewaters and is an alternative to commercial adsorbents due to its low-cost and abundance in the paper industries.     

Treatment of textile dye wastewater by using an electrochemical bipolar disc stack reactor

Textile dye house wastewater from a reactive dye processing unit was treated by using an electrochemical oxidation technique. The experiments were carried out in an electrochemical bipolar disc reactor using RuO₂ coated on titanium as anode and titanium as cathode. The sodium chloride present in the effluent was used as supporting electrolyte. Operating parameters such as current density, reservoir hold‐up and electrolysis time were studied for maximum Chemical Oxygen Demand (COD) reduction and other relevant parameters such as current efficiency and power consumption per kg of COD removal were calculated. The higher flow rate and lower reservoir hold‐up resulted in improved COD removal. The applied current density was also found to significantly influence the reduction of COD. A suitable mathematical model is also proposed to illustrate the relationship between the basic parameters. Pseudo mass transfer coefficients were also evaluated for different experimental conditions. Copyright © 2004 Society of Chemical Industry     

阴离子交换纤维对活性染料废水的脱色研究

采用自制的聚丙烯基强碱阴离子交换纤维(IEF)处理活性染料模拟废水,讨论了IEF用量、介质pH值、温度等对活性艳黄X-RG溶液的脱色率和脱色速率的影响。对比了IEF与树脂、锰钾矿的脱色效果, 进行了动态脱色和再生实验。结果表明,IEF用量、pH值和温度的增加有利于脱色速率的提高,对活性艳黄和活性艳红染料的脱色率在96%以上,脱色40 mm即能达到高脱色率IEF对活性染料的脱色效果明显优于天然锰钾矿和D296强碱性阴离子交换树稽,IEF能够再生重复使用     

Degradation of cationic dye methylene blue by ozonation assisted with kaolin

An enhanced ozonation process, methylene blue (MB) wastewater treated by MnO₂/O₃ assisted with kaolin in a slurry reactor, at room temperature and atmospheric pressure, MB wastewater can be effectively purified, a chemical oxygen demand (COD) of 88.3% and a decoloration rate of 98.9% were obtained in 10 min at pH 11. Compared with MnO₂/O₃ catalytic ozonation (16.0% of decoloration and 33.3% of COD reduction), decoloration and COD reduction were markedly increased, indicating that kaolin can significantly improve the catalytic ozonation process. According to the experimental results, the hypothetical mechanism of degradation and the reaction kinetics were also proposed. COD reduction can be described by a second-order model and the reaction rate constant in the presence of kaolin was higher than that of absence of kaolin.     

The kinetics of sorption of basic dyes from aqueous solution by sphagnum moss peat

The kinetics of sorption of three basic dyes, namely, Chrysoidine (BO2), Astrazon Blue (BB3) and Astrazone Blue (BB69) onto sphagnum moss peat have been investigated. The study focuses on the application of three sorption kinetic models for predicting the uptake of basic dyes. The sorption behaviour is found to be second order, based on the assumption of a pseudo-second order mechanism. The rate constant of sorption, the equilibrium capacity and initial sorption rate with the effect of various peat doses and initial dye concentrations have also been predicted.     

Removal of basic and acid dyes from aqueous solutions by a waste containing boron impurity

In this study, batch experiments were carried out for the sorption of basic blue 41 (BB 41), and acid blue 225 (AB 225) onto boron waste (BW) from boron enrichment plant. The operating variables studied are the initial dye concentration, contact time, solution pH, and adsorbent dosage. The experimental equilibrium data were analyzed by using various adsorption isotherm models and the results have shown that the adsorption behavior of AB 225 and BB 41 could be described well reasonably by Langmuir and Temkin isotherms, respectively. Kinetics studies indicated that the adsorption of both dyes follow pseudo-second-order kinetics. The sorption of basic dye increased at high pH values, whereas the opposite was true for acidic dye. The results indicate that BW could be employed as low-cost alternatives to the commercially available adsorbents in wastewater treatment for the removal of acid and basic dyes.     

Theoretical maximum dye-uptake of acrylic fiber to basic dye

The theoretical maximum dye-uptake of the fiber to dye is considered to be related to the fraction of the polymer segment which is mobile. This is studied by dyeing the acrylic fiber at temperatures within a 40 °C range while treating the samples with different carriers. The relation of the equilibrium dye-uptake (dyeability) of the acrylic fiber to the structural parameter, , with the presence or absence of carrier in solution, is linear, confirming the validity of the hypotheses, where (tanδ)_c is the loss tangent correlated at a temperature of 20 °C. Moreover, The effect of the carrier in swelling the amorphous region of the acrylic fiber was less effective as temperature rose beyond T _g(mechanical).     

Removal of basic blue 41 from aqueous solution by carboxymethylated Posidonia oceanica

The aim of this work is to improve the retention capacity already noticed for the raw Posidonia towards basic dyes and notably for basic blue 41 (BB41). To improve the fixation rate of these cationic entities, we have undertaken the introduction of carboxymethylate groups on the raw Posidonia. Thus, we have obtained materials with various carboxymethylate groups contents (from 10 to 30%). We have then studied the fixation capacities of BB41 on the different materials. We have noticed that the retention capacity of modified Posidonia was improved compared to the raw one. We have studied the effect of different parameters influencing the fixation capacities such as initial dye concentration, support dose, contact time, pH, carboxymethylate groups content, and temperature. This phenomenon of retention is compared to classic models of Langmuir and Freundlich. Some thermodynamic parameters such as free energy (ΔG⁰), enthalpy (ΔH⁰), and entropy (ΔS⁰) changes have been studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1215–1225, 2007