Adsorption of cationic dyes from aqueous solution using hydrophilic silica aerogel via ambient pressure drying

In order to remove the organic dyes of textile waste water, the silica aerogel was successfully prepared by using E-40 as a novel precursor and then dried in ambient pressure. The synthesized sample was verified by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). After calcining, the hydrophilic silica aerogel (HSA) was used as adsorbent to remove Methylene Blue (MB), Malachite Green (MG), and Gentian Violet (GV) from aqueous solution. The effects of initial concentration of dyes and adsorbent dosage on the adsorption process were examined. It was found that HSA showed excellent adsorption capacities, the maximum percentage of removal dyes could reach 98%. Herein, the Langmuir, Freundlich and de Boer-Zwikker isotherm modes were employed to discuss the adsorption behavior. The results indicated that the de Boer–Zwikker model can effectively describe the adsorption behavior. Besides, the HSA could be utilized as the recyclable adsorbent in degradation experiment, after five cycles, no obvious loss of adsorption capacity was found. As an efficient, low-cost, environmental friendly and recyclable adsorbent, silica aerogel is expected to be used for dyes removal.     

Adsorption of cationic dyes from aqueous solution using hydrophilic silica aerogel via ambient pressure drying

In order to remove the organic dyes of textile waste water, the silica aerogel was successfully prepared by using E-40 as a novel precursor and then dried in ambient pressure. The synthesized sample was verified by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). After calcining, the hydrophilic silica aerogel (HSA) was used as adsorbent to remove Methylene Blue (MB), Malachite Green (MG), and Gentian Violet (GV) from aqueous solution. The effects of initial concentration of dyes and adsorbent dosage on the adsorption process were examined. It was found that HSA showed excellent adsorption capacities, the maximum percentage of removal dyes could reach 98%. Herein, the Langmuir, Freundlich and de Boer-Zwikker isotherm modes were employed to discuss the adsorption behavior. The results indicated that the de Boer-Zwikker model can effectively describe the adsorption behavior. Besides, the HSA could be utilized as the recyclable adsorbent in degradation experiment, after five cycles, no obvious loss of adsorption capacity was found. As an efficient, low-cost, environmental friendly and recyclable adsorbent, silica aerogel is expected to be used for dyes removal.     

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.     

Adsorptive removal of dye from real textile wastewater using graphene oxide produced via modifications of hummers method

Abstract

This work focused on producing different graphene oxide (GO) samples for further application in the adsorptive removal of dyes from real textile wastewater. Among all conditions tested, the sample produced using KMnO₄ and no sonication bath exhibited the best performance. Before the experiments using wastewater, kinetics and equilibrium of adsorption studies were performed with Methylene Blue (MB) dye. Experimental data showed the isotherm fitted the Freundlich model, and kinetic results fitted the pseudo-second order model. Theoretical q_max was 308.11?mg.g^?1 and over 90% removal of MB was reached in approximately 5?min. Although GO has been widely applied to remove cationic and anionic dyes from water, not many studies have presented GO as an adsorbent for real textile wastewater treatment. In 30?min, GO removed nearly 85% of turbidity and over 60% of color from a real sample, indicating that GO might be an excellent alternative to treat textile wastewater.     

From pollutant to solution of wastewater pollution: Synthesis of activated carbon from textile sludge for dye adsorption

Adsorption is an important process in wastewater treatment,and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon.This study investigated the adsorption behaviour of Reactive Black 5(RB5)and methylene blue(MB)onto activated carbon produced from textile sludge(TSAC).The activated carbon was synthesized through chemical activation of precursor followed with carbonization at 650°C under nitrogen flow.Effects of time(0–200 min),pH(2–10),temperature(25–60°C),initial dye concentration(0–200 mg·L~(-1)),and adsorbent dosage(0.01–0.15 g)on dye removal efficiency were investigated.Preliminary screening revealed that TSAC synthesized via H_2SO_4activation showed higher adsorption behaviour than TSAC activated by KCl and ZnCl_2.The adsorption capacity of TSAC was found to be 11.98 mg·g~(-1)(RB5)and 13.27 mg·g~(-1)(MB),and is dependent on adsorption time and initial dye concentration.The adsorption data for both dyes were well fitted to Freundlich isotherm model which explains the heterogeneous nature of TSAC surface.The dye adsorption obeyed pseudo-second order kinetic model,thus chemisorption was the controlling step.This study reveals potential of textile sludge in removal of dyes from aqueous solution,and further studies are required to establish the applicability of the synthesized adsorbent for the treatment of waste water containing toxic dyes from textile industry.     

Adsorption Behavior of Basic Dyes on Activated Clay

Abstract

Activated clay was used to study the adsorption behavior of dyestuffs in synthetic wastewater containing dyestuffs. Three basic dyes were used: C.I. Basic Red 18 (or BR18), C.I. Basic Red 46 (BR46), and C.I. Basic Yellow 28 (BY28). Adsorption occurred almost instantaneously upon contact. The mechanism of adsorption was explained by a charge to the electrostatic attractive force described in the Langmuir adsorption isotherm. The mass transfer coefficient was also calculated by the external mass transfer model in an adsorbent according to Mckay et al. Parameters including species of basic dyes, initial concentration, temperature, size of adsorbent, and NaCl were extensively investigated.     

Adsorption of reactive yellow 145 onto chitosan coated magnetite nanoparticles

Removal of dyes from the industrial discharge water is an important issue for safety of the environment. In this study, magnetic (magnetite, Fe₃O₄) nanoparticles were coated with chitosan (CS) and the efficiency of these chitosan coated magnetic nanoparticles (Fe₃O₄‐CS) for the adsorption of a reactive textile dye (Reactive Yellow 145, RY145) was examined first time in literature. TEM, XRD, and EPR results revealed that the thickness of the coat was about 2–5 nm, no phase change in the spinel structure of magnetic particles existed after coating, and particles had paramagnetic property, respectively. Adsorption of RY145 on Fe₃O₄‐CS nanoparticles occurs according to Langmuir model in the temperature range 25°C–45°C with a maximum adsorption capacity of 47.62 mg g^?1 at 25°C, in aqueous media. Thermodynamic parameters demonstrated that the adsorption process was endothermic and spontaneous, and the maximum desorption of the dye was 80% over a single adsorption/desorption cycle. In this study, the high efficiency of the CS coated magnetic nanoparticles in the adsorption and removal of reactive dyes from water was shown on model RY145. This type of nanoparticles can be good candidates in industrial applications for the decolorization of waste waters. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Adsorption of methylene blue from aqueous solutions by modified expanded graphite powder

The modified expanded graphite (MEG) powder was used as a porous adsorbent for the removal of the cationic dye, methylene blue (MB), from aqueous solutions. The dye adsorption experiments were carried out with the bath procedure. Experimental results showed that the basic pH, increasing initial dye concentration and high temperature favored the adsorption. The dye adsorption equilibrium was attained rapidly after 5 min of contact time. Experimental data related to the adsorption of MB on the MEG under different conditions were applied to the pseudo-first-order equation, the pseudo-second-order equation and the intraparticle diffusion equation, and the rate constants of first-order adsorption (k₁), the rate constants of second-order adsorption (k₂) and intraparticle diffusion rate constants (k_int) were calculated, respectively. The experimental data fitted very well in the pseudo-second-order kinetic model. The thermodynamic parameters of activation such as Gibbs free energy, enthalpy, and entropy were also evaluated. The results indicated that the MEG powder could be employed as an efficient adsorbent for the removal of textile dyes from effluents.     

Removal of plant poisoning dyes by adsorption on Tomato Plant Root and green carbon from aqueous solution and its recovery

The organic dyes directly pollute the soil, water, plants and all living systems in the environment. The dyes like cationic Methylene blue (MB) and Crystal violet (CV) adsorption has been studied on Tomato Plant Root powder (TPR) and green carbon from aqueous solution for identifying the plant poisoning nature of cationic dyes. TPR powder is a cellulose material and green carbon is prepared from TPR powder by an ecofriendly method. The dyes adsorption mechanism on basic surface of cellulose and neutral surface of green carbon are correlated to evaluate the plant poisoning nature of organic dyes. The adsorption parameters were optimized to maximum adsorption. The maximum uptake of both dyes on TPR was 97% at 15 min and on carbon is 18% (CV) & 20% (MB) at 30 min. The adsorptions of MB and CV on TPR powder followed Freundlich and Langmuir adsorption isotherms and pseudo second order kinetics. The ?S^o, ?H^o and ?G^o of adsorption on TPR are calculated. The dyes recovery has been studied from dyes adsorbed TPR and green carbon. The adsorption mechanism and dye recovery studies proved the plant poisoning nature of MB and CV.     

A new electrode reactor with in-built recirculation mode for the enhancement of methylene blue dye removal from the aqueous solution: Comparison of adsorption,electrolysis and combined effect

The removal of basic dye such as methylene blue (MB) dye from the synthetic wastewater was experimentally investigated using an electrolytic cell (EC), adsorption and the combined effect of EC and adsorption technology called a three-phase three-dimensional electrode reactor (TPTDER). The performance of the each technology was checked on the basis of the efficiency of the systems. The experimental results are expressed in terms of the removal efficiency of the dye molecules. The results show that the TPTDER could efficiently remove the dye molecules from the aqueous solutions when compared with the EC and adsorption process. The removal efficiency reached as high as about 99% for an initial MB dye concentration in the range of 100–1,000 mg/L by TPTDER for 10 min at 12 V cell voltage and at specific airflow conditions. It was also observed that the removal of dye molecules depends upon the initial solution pH, applied cell voltage, contact time, and initial dye concentration. The recyclability of the particle electrodes in the TPTDER process was also checked. These findings suggest that TPTDER is a promising technology for the removal of dyes from the aqueous solution, and can be applied to the removal of dyes from the industrial effluents.     

Photoinitiated surface grafting of synthetic fibers,IV. Applications of textile dyes onto surface-photografted synthetic fibers

High-strength polyethylene (HSPE), polypropylene (PP), poly(ethylene terephthalate) (PET), and poly(vinyl alcohol) (PVA) textile yarns have been surface-photografted with various functional monomers, such as acrylic acid (AA), acrylamide (AM), glycidyl acrylate (GA) and 4-vinyl pyridine (VP), by means of the continuous presoaking process developed. The dyeing of these surface-modified yarns with various textile dyes has been investigated. In general, considerable improvements of dyeability have been observed. The dye adsorption of the surface-photografted fibers is influenced by many factors, such as type of fiber, amount and properties of the functional monomer grafted on the surface of the fibers, type of textile dye, etc. The fibers surface-grafted with a monomer containing basic groups, such as acrylamide and 4-vinyl pyridine, are efficiently dyed with an acid dye. Conversely, a fiber surface-grafted with acidic functional monomer is easily dyed to deep shades with basic dyes. The dye adsorption increases monotonically with increasing grafting measured in ESCA spectra as relative intensities of relevant lines. The ungrafted HSPE, PP and PET fibers can be dyed to some extent with certain dyes. In the present work, the dye adsorption increased by 3.4 times for HSPE fiber grafted with GA and dyed with the metal complex dye IO, by 7.9 times for PP fiber grafted with AA and dyed with the basic dye MB, by 6.1 times for PET with AM and with the direct dye SL, and by about 15.3 times for PVA with VP and with the acid dye TE.     

Chitosan intercalated montmorillonite: Preparation, characterization and cationic dye adsorption

Chitosan intercalated montmorillonite (Chi-MMT) was prepared by dispersing sodium montmorillonite (Na⁺-MMT) into chitosan solution at 60 °C for 24 h. The Chi-MMT was characterized by XRD, XRF and FT-IR. The intercalation was accomplished via the ion-exchange of Na⁺ ions with –NH₃⁺ of chitosan, resulting in the expansion of d₀₀₁ from 1.42 nm of Na⁺-MMT to 2.21 nm of Chi-MMT. The chitosan content in the Chi-MMT measured by TGA was about 17 mass%. The adsorption capacity of Chi-MMT was investigated in comparison with the starting Na⁺-MMT and chitosan using three different cationic dyes, i.e. basic blue 9 (BB9), basic blue 66 (BB66) and basic yellow 1 (BY1). The Chi-MMT showed the highest adsorption capacity in the range of 46–49 mg/g when the initial dye concentration was 500 mg/L, being equivalent to 92–99 wt.% of dye removal. The adsorption capacities of Chi-MMT for all basic dyes increased with an increase of initial dye concentration. An increase of adsorption capability of Chi-MMT was attributed to the existence of intercalate-chitosan. It could enlarge the pore structure of Chi-MMT, facilitating the penetration of macromolecular dyes, and also electrostatically interact with the applied dyes. These results indicated the competency of Chi-MMT adsorbent for basic dye adsorption.     

Adsorption behavior of cationic dyes on citric acid esterifying wheat straw: kinetic and thermodynamic profile

The kinetic and thermodynamic behaviors of cationic dye adsorption onto citric acid esterifying wheat straw (EWS) from aqueous solution were investigated. Two cationic dyes, methylene blue (MB) and crystal violet (CV) were selected as adsorbates. The kinetic and thermodynamic parameters of dye adsorption were examined with a batch system by changing various experimental factors (e.g. initial pH, EWS dosage, dye concentration, contact time, temperature). The MB and CV removal ratios came up to the maximum value beyond pH 4. The 2.0 g/L or up of EWS could almost completely remove MB and CV from 250 mg/L of dye solution. The adsorption percentages of MB and CV kept above 95% over a range from 50 to 350 mg/L of dye concentration when 2.0 g/L of EWS was used. The isothermal data followed the Langmuir model. The adsorption processes could be described by the pseudosecond-order kinetic model. The dual linear plots of intraparticle diffusion indicated that two intraparticle diffusion steps occurred in the dye adsorption processes. The thermodynamic study indicated that the adsorptions of dyes were spontaneous and endothermic. High temperatures favored the adsorption processes.     

Equilibrium studies on the adsorption of reactive azo dyes into zeolite

Zeolite was used as a low-cost adsorbent to evaluate its ability to remove color from textile effluents. The zeolit (clinoptilolite) used in this study is a natural clay mineral from the Gbrdes region of Turkey. The adsorption of reactive dyes into zeolite was investigated by a series of batch adsorption experiments. Three reactive dyes (Everzol Black, Everzol Red, Everzol Yellow) were used in laboratory studies. Adsorption test were carried out as a function of solids concentration, conditioning time and dye concentration. The degree of hydrophilicity was found to play an important role in the uptake of reactive dyes. The adsorption results indicated that natural zeolite has a limited adsorption capacity for reactive dyes but can be distinctly improved by modifying its surfaces with quaternary amines. A comparison of natural and modified zeolites at 5% solids concentration indicated that, while the adsorption densities of dyes with natural zeolite yielded negative or slightly positive values, those with modified zeolite gave adsorption densities in the range of 2.9 to 7.6 mg/g.     

Dye removal from colored textile wastewater using chitosan in binary systems

In this paper, the removal of two anionic dyes from textile effluent in single and binary systems was investigated. Direct Red 23 and Acid Green 25 were used as anionic dyes. The surface characteristics of chitosan were investigated using Fourier transform infrared. The effects of operational parameters such as chitosan dosage, initial dye concentration, salt and pH on dye removal were studied. The isotherms of dye adsorption were investigated. It was found that the isotherm data of Direct Red 23 and Acid Green 25 in single and binary systems followed Tempkin isotherm. In addition adsorption kinetics of dyes was studied in single and binary systems and rate sorption was found to conform to pseudo-second order kinetics with a good correlation. Results indicated that chitosan could be used as a biosorbent to remove the anionic dyes from contaminated watercourses in both single and binary systems of pollutants.     

Adsorption Performances of Cationic Dyes from Aqueous Solution on Pyromellitic Dianhydride Modified Sugarcane Bagasse

In this study, pyromellitic dianhydride (PMDA) modified waste sugarcane bagasse (SCB) was prepared through a simple method to remove two cationic dyes: methylene blue (MB) and malachite green (MG) from aqueous solution. Adsorption performances of MB and MG on the modified sorbent were investigated in details. The adsorption capacities of the modified SCB for MB and MG were 571.4 and 377.4 mg g^?1, respectively, which were 10 and 12 times than that obtained on the unmodified SCB. Adsorption kinetics study showed equilibriums were obtained after adsorption for 13 hours for both dyes. The modified SCB could be used repeatedly after regeneration. FTIR results showed that carboxyl and hydroxyl groups on the modified SCB involved in adsorption process.     

Removal of Reactive Dyes using Magnetically Separable Trametes versicolor Cells as a New Composite Biosorbent

Magnetically modified Trametes versicolor cells were used for biosorption of Reactive Blue 13 (RB13), Reactive Yellow 85 (RY85) and Reactive Violet 1 (RV1). Percent biosorption values and maximum adsorption capacities of 98.30% and 135.35 mg g^?1 for RB13, 96.02% and 125 mg g^?1 for RY85, and 98.56% and 227.27 mg g^?1 for RV1 were observed under optimal conditions. The biosorption of all dyes was exothermic in nature. The biosorbent was characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and magnetic force microscopy. The Langmuir model was found to be most suitable for describing the biosorption of all dyestuffs. The experimental data fitted very well the pseudo second order kinetic model.     

Preparation of poly (acrylic acid) containing core‐shell type resin for removal of basic dyes

BACKGROUND: A core‐shell type carboxylic acid modified resin was prepared and dye sorption characteristics of the resin were investigated. The resulting grafted resin material has been shown to be an efficient sorbent for removal of basic dyes from water as a result of the carboxylic acid group's affinity towards basic dye molecules. RESULTS: The resin was characterized using Fourier transform infrared spectroscopy (FT‐IR) and titrimetric methods. The basic dyes (methylene blue and crystal violet) were removed by contacting the swollen resin with aqueous dye solutions at room temperature. The adsorption capacities of resin were determined by colorimetric analysis of the residual dye content in the adsorption medium, which gave capacities for methylene blue and crystal violet of 300 and 250 mg g^?1 resin, respectively. The prepared resin is also able to remove basic dyes completely from dilute aqueous dye solutions. Batch kinetic sorption experiments determined that a pseudo‐second‐order rate kinetic model was applicable. CONCLUSION: Flexibility of the polymer side chains is expected to provide pseudo‐homogeneous reaction conditions and easy accessibility of the functional groups involved. The adsorbents are expected to have the advantage of mobility of the grafted chains in the removal of basic dyes from aqueous mixtures. The resin has potential as an adsorbent for removal of basic dyes for use over a wide pH range. Copyright © 2011 Society of Chemical Industry     

Multifunctional amphoteric resin to remove both anionic and cationic dyes from aqueous solution

This study reports the synthesis and characterization of a new amphoteric resin, which can be used for the removal of both cationic, methylene blue (MB) and anionic dyes, reactive red-120 (RR-120). The amphoteric resin was characterized by ATR-FTIR, SEM–EDX, TGA/DTA, DLS, BET analysis and also its surface pHpzc was determined. The prepared resin has micro porous structure and its particle size was at the nano level. The prepared amphoteric resin showed high removal affinity for MB in both acidic and basic medium, while for RR-120 high removal affinity in acidic medium. Moreover, it was observed that the amphoteric resin has exhibited almost 100% dye removal up to 600 ppm for MB and up to 300 ppm for RR-120, respectively. The adsorption behavior of both dyes on the amphoteric resin is in agreement with the Langmuir isotherm and the pseudo-second order kinetic model and also electrostatic interaction is dominant in adsorption. Its capacity was slightly low for the MB than that of the commercial activated carbon, but higher for the RR-120. Furthermore, it was observed that the amphoteric resin almost did not lose its high removal efficiency in the concentrated matrix environment for both dyes. After five repeated adsorption–desorption cycles, the high removal efficiency of the resin for the MB (almost 100%) unchanged, but for the RR-120 decreased to 83%.     

地质聚合物微球的制备及对染料的吸附

以偏高岭土和改性水玻璃为原料，采用分散悬浮固化法制备偏高岭土基地质聚合物微球（GM）。使用扫描电子显微镜、比表面积及孔径分布测试仪、傅里叶变换红外光谱仪和X射线粉末衍射仪对其进行结构表征，并研究了GM对亚甲基蓝的吸附性能。结果表明：GM对亚甲基蓝的吸附基本符合准二级动力学模型和Langmuir吸附等温线模型，333 K时最大理论吸附量为100.1 mg/g。GM对亚甲基蓝的吸附是自发吸热过程。使用后的GM在5次循环利用后，GM对MB的去除率仍然可达81.56%，易于回收和再生。分析了GM对不同阴阳离子型染料的吸附效果，结果表明，GM对阳离子型染料具有选择性吸附。GM是一种低价、有效、绿色、可循环利用的吸附剂，可用于去除水中阳离子型染料污染物。