Surface modification and ternary system dye removal ability of manganese ferrite nanoparticle

In this paper, the surface of magnetic manganese ferrite nanoparticles (MFN) was modified using cetyl trimethylammonium bromide (CTAB). The modified MFN was studied using Fourier transform infrared spectroscopy (FTIR). The adsorption capacity of surface modified MFN (MFN-CTAB) was investigated for dye removal for single and ternary systems. Three anionic dyes, C.I. Direct Red 80 (DR80), C.I. Direct Red 31 (DR31), and C.I. Acid Blue 92 (AB92), were used as model compounds. The effects of operational parameters on dye removal (i.e. adsorbent dosage, dye concentration and salt) and the kinetic and isotherm of dye adsorption were studied. The adsorption kinetic for the dyes was found to be well described by the pseudo-second order model. The maximum dye adsorption capacity (Q ₀) of MFN-CTAB for DR80, DR31 and AB92 was 83 mg/g, 59 mg/g and 70 mg/g, respectively. The adsorption isotherm data were analyzed using the Langmuir, Freundlich, and Temkin equations. The results revealed that the Langmuir model fitted the adsorption data better. The results showed that the MFN-CTAB as a magnetic adsorbent might be a suitable alternative to remove dyes from colored aqueous solutions.     

Dye removal using polymeric adsorbent from wastewater containing mixture of two dyes

In this paper, poly(amido primary-secondary amine) (PAPSA) as a high capacity polymeric adsorbent was synthesized. Dye removal ability of PAPSA from single and binary systems was investigated. The functional groups of PAPSA were studied using Fourier transform infrared (FTIR). Acid Blue 92 (AB92), Direct Red 23 (DR23), and Direct Red 81 (DR81) were used as model compounds. The kinetic and isotherm of dye adsorption were studied. The effect of operational parameter such as adsorbent dosage, dye concentration, and pH on dye removal was evaluated. It was found that adsorption of dyes onto PAPSA showed Langmuir isotherm. The maximum dye adsorption capacity (Q ₀) of PAPSA was 10000 mg/g, 12500 mg/g, and 10000 mg/g for AB92, DR23, and DR81, respectively. Adsorption kinetic of dyes followed pseudo-second order kinetics. Dye desorption tests showed that the dye release of 85 % for AB92, 91 % for DR23 and 89 % for DR81 were achieved in aqueous solution at pH 12. The results showed that the PAPSA as a polymeric adsorbent with high dye removal ability might be a suitable alternative to remove dyes from colored wastewater.     

Eco-friendly biopolymer/clay/conducting polymer nanocomposite: Characterization and its application in reactive dye removal

In this study starch-montmorillonite/polyaniline (St-MMT/PANI) nanocomposite was synthesized by chemical oxidative polymerization of aniline in the presence of starch-montmorillonite nanocomposite dispersion. The prepared ternary nanocomposite was characterized using FT-IR, XRD, SEM, TGA and TEM techniques. XRD patterns combined with TEM results confirmed the intercalation of MMT in the starch matrix. SEM micrographs revealed the growth of polyaniline over the surface of the St-MMT nanocomposite. The St-MMT/PANI nanocomposite was used for the adsorption of a reactive dye. Batch removal experiment results showed complete removal of dye in a very short contact time. Further investigations indicated that the removal mechanism was based on both the adsorption and electrostatic attraction between nanocomposite and dye molecules. The experimental data were well fitted to the Langmuir isotherm and pseudo-second-order kinetic model. The adsorption capacity of reactive dye on St-MMT/PANI nanocomposite was 91.74 mg g^?1. All these results demonstrated the effectiveness of the hybrid system as an efficient adsorbent for removal of reactive dyes from textile effluents.     

Synthesis of urethane polycarboxylate as a novel adsorbent and its binary system dye removal ability from aqueous solution

In this paper, urethane polycarboxylate (UPC) as a novel adsorbent was synthesized and characterized. Dye removal ability of UPC from aqueous solution of single and binary systems was studied. Fourier transform infrared (FTIR) was used to characterize UPC. Basic Blue 41 (BB41), Basic Red 18 (BR18), and Basic Violet 16 (BV16) were used as cationic dyes. Dye removal isotherm and kinetic were evaluated. The effect of UPC dosage, initial dye concentration, and inorganic anions on dye removal was investigated. The capacity of UPC to remove BB41, BR18, and BV16 were 333 mg/g, 278 mg/g, and 222 mg/g, respectively. Dye removal kinetics and isotherm using UPC were fitted with the pseudo-second order and Langmuir model, respectively. The results showed the UPC might be used as a dye adsorbent to treat multicomponent systems containing cationic dyes.     

Modified polyamide 66 fibers for the removal of reactive dyes from aqueous suspension

In this paper, we report the modification of polyamide sample (PA) with different contents of chitosan (CS) using citric acid (CA) as a cross-linker [PA-CA-CS]. New materials were confirmed to be formed in PA using FT-IR spectrum. It is also checked in terms of the change in thermal stability event and decomposition behavior in thermogravimetry through TG-DTA instruments. Then, the ability of unmodified and modified supports was tested for the adsorption of two reactive dyes i.e. Cibacron Brilliant Yellow 3G-P and Cibacron Blue P-3R. Sorption experiments were performed under varying several experimental conditions such as pH, contact time, initial dye concentration, and temperature. The isotherm and kinetic models were undertaken to assess the dye removal mechanism. The applicability of Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin equations was checked and data were fitted using Langmuir model. The second-order equation was shown to fit the adsorption kinetics. Data gleaned from both thermodynamic results and modeling data indicate that the adsorption follows a chemical and exothermic process.     

Binary catalyst system dye degradation using photocatalysis

In this paper, soy meal hull activated carbon (SMHAC) and titania nanoparticle (TiO₂) were used as catalysts to degrade dyes. Activated carbon was prepared using soy meal hull. Degradation of dyes using single and binary catalyst systems was studied. Textile dyes were used as model pollutants. Photocatalytic dye degradation and mineralization were studied using UV-Vis spectrophotometer and ion chromatography (IC). The effects of pH, initial dye concentration, and salt on dye degradation were investigated. Dye solutions were decolorized completely (100 %). The presence of salts decreased dye degradation rate. Degradation of dyes followed first order kinetics model. Formate, acetate, and oxalate were detected as dominant aliphatic intermediates during dye degradation process. Nitrate, sulfate, and chloride anions were detected as dye mineralization products.     

Magnetically modified spent grain for dye removal

Spent grain, the major by-product of the brewing industry, was magnetically modified by contact with water-based magnetic fluid. The prepared material has been used as a new inexpensive magnetic adsorbent for the removal of water-soluble dyes. The dye adsorption could be described both with the Langmuir and Freundlich isotherms. The maximum adsorption capacities reached the value up to 72.4 mg of dye (Bismarck brown Y) per g of dried magnetically modified spent grain.     

Adsorption and dyeing characteristics of reactive dyes onto cotton fiber in nonionic Triton X-100 reverse micelles

The nonionic reverse micelles used for dyeing cotton fiber were prepared with a non-ionic surfactant Triton X-100 (TX-100) by injecting small amount of reactive dye aqueous solution. The adsorption capacity of three water-soluble anionic azo dyes including Reactive Blue 222, Reactive Red 195 and Reactive Yellow 145 onto cotton fiber was investigated. The Langmuir and Freundlich isothermals were employed to model the adsorption data. In addition, the color strength and fixation rate of cotton fabrics dyed in the reverse micelles and bulk water were examined and compared. The salt and alkali as influencing factors were also discussed. The FT-IR spectra were employed to study the polarity of water added in reverse micelles. The results indicated that the adsorption of the dyes onto cotton showed better agreement with Langmuir model. The adsorption process was monolayer adsorption. Reactive Yellow 145 with lower negative charge and higher hydrophilicity exhibited the higher adsorption capacity. The fixation percentage and color strength of the cotton fiber dyed in TX-100 reverse micelles was higher than those in bulk water. The polarity of water in TX-100 reverse micelles was lower than that in bulk water.     

Preparation and acid dye adsorption behavior of polyurethane/chitosan composite foams

We prepared a series of polyurethane(PU)/chitosan composite foams with different chitosan content of 5∼20 wt% and investigated their adsorption performance of acid dye (Acid Violet 48) in aqueous solutions with various dye concentrations and pH values. It was observed that PU/chitosan composite foams exhibited well-developed open cell structures. Dye adsorption capacities of the composite foams increased with the increment of chitosan content in composite foams, because amine groups of chitosan serve as the binding sites for sulfonic ions of acid dyes in aqueous solutions. In addition, dye adsorption capacities of composite foams were found to increase with decreasing the pH value, which stems from the fact that the enhanced chemisorption between protonated amine groups of chitosan and sulfonic ions of acid dye is available in acidic solutions. The dye adsoption kinetics and equilibrium isotherm of the composite foams were well described with the pseudo-second order kinetic model and Langmuir isotherm model, respectively. The maximum adsorption capacity (q _max) for the PU/chitosan composite foams with 20 wt% chitosan content is evaluated to be ca. 30 mg/g.     

Organic-inorganic hybrid of chitosan/poly (vinyl alcohol) containing yttrium(III) membrane for the removal of Cr(VI)

In this present study, an organic-inorganic hybrid membrane was prepared by embedding yttrium(III) into chitosan matrix for the removal of Cr(VI) from aqueous solutions. Several techniques, including fourier infrared spectrum (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM) are employed to characterize the properties of the membrane. The mechanical properties of the membrane were also examined. The chitosan/poly(vinyl alcohol) containing yttrium(III) (CY) membrane was experimentally used for the removal of Cr(VI) ions from aqueous solution under the optimized conditions. The results showed that the adsorption capacity for the removal of Cr(VI) ions was enhanced when yttrium(III) was introduced. The adsorption data from the experiment were fit well by Langmuir isotherm. Based on Langmuir model, q _m was calculated to be 38.48 mg g^?1. Kinetic study results indicated that the adsorption process followed a pseudo-second-order kinetics.     

Decolorization of dyes using immobilized laccase enzyme on zinc ferrite nanoparticle from single and binary systems

In this paper, laccase enzyme was immobilized onto zinc ferrite nanoparticle and the characteristics of enzyme immobilized nanoparticle (EIN) were evaluated by Fourier transform infrared (FTIR) and scanning electronic microscope (SEM). Enzymatic decolorization of dyes using EIN from single and binary systems was studied. Direct red 31 (DR31) and Acid blue 92 (AB92) were used as model dyes. The effects of several parameters such as EIN dosage, pH, and dye concentration on decolorization of dyes from single and binary systems were evaluated. The optimized amount of EIN, reaction time, and pH for decolorization of dyes from single and binary systems were 0.2 g (for DR31) and 0.3 g (for AB92), 40 min, and 3 in single systems and 0.2 g (for DR31 and AB92), 40 min, and 3 in binary systems, respectively. Dye decolorization kinetics followed Michaelis-Menten model. The results showed that enzymatic process using EIN was effective method to decolorize dyes from single and binary systems.     

Cellulose-based porous adsorbents with high capacity for methylene blue adsorption from aqueous solutions

A novel cellulose-based porous adsorbent with high adsorption capacity for methylene blue (MB) was prepared by free radical polymerization methods. The obtained polymer grafting rate and dye removal efficiency are as high as 338.64 % and 97.74 %, respectively, when the dosage of monomer is 4.5 g, the polymerization condition is 3 h at 70 °C. The cellulose-based adsorbent showed high mechanical properties and good flexibility. The Langmuir isotherm model revealed that the maximum theoretical adsorption capacity of this material for methylene blue was 1734.816 mg g-1 at pH 9.0 at 313 K, which is higher than the values observed for other adsorbents. Scanning electron microscopy (SEM) showed that the cellulose-based adsorbent exhibits a typical well-defined porous and interconnected three-dimensional framework structure, which is benefits to dye adsorption. The adsorption kinetics (pseudo first-order, pseudo-second-order, and intraparticle diffusion models) was also studied, and the pseudo-second-order model fitted MB adsorption better than the pseudo-first-order and intraparticle diffusion models at different initial dye concentrations (500-3000 mg l ^-1). The novel polyacrylic acid-grafted quaternized cellulose (PAA-g-QC) adsorbent is thus potentially useful for the treatment of dye-contaminated wastewater.     

Dye Adsorption from Aqueous Solution by Cellulose/Chitosan Composite: Equilibrium,Kinetics, and Thermodynamics

A novel eco-friendly porous adsorbent of cellulose (CE)/chitosan (CS) aerogel was prepared through sol-gel process and freeze-drying to remove Congo Red (CR). A series of aerogels were prepared by adjusting the mass ratios of CE and CS. Composite aerogels were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). SEM images showed that it was possible to change the structure of the aerogel by adjusting the amount of chitosan. The effects of dosage of chitosan, initial pH, temperature, adsorbent dosage, contact time, and initial dye concentration on adsorption capacities for CR were studied in detail. Batch adsorption studies showed that aerogel exhibited maximum removal efficiency to CR at a composite ratio of 1:3 and dosage of 2.5 g/l. CE/CS aerogel had excellent adsorption capacities for CR at a pH range of 3-11, which indicated stability of the aerogel in both acidic and alkaline conditions. CR adsorption on the composite aerogel fitted pseudo-second-order kinetics and Langmuir isotherm. The Langmuir isotherm model revealed that the maximum theoretical adsorption capacity of this material for CR was 381.7 mg/g at pH 7.0 at 303 K for 24 h. The adsorption mechanism included electrostatic and chemical interactions. The results indicated that the adsorption capacity of CE/CS aerogels was higher than the other chitosan composites adsorbents.     

Exploration of biosorption potential of forest industry by-product for removal of reactive dye from aqueous solution

Natural sawdust of Calabrian pine was explored as low-cost industrial by-product for a hetero-bireactive dye removal from aqueous solution in this study. Batch experiments were carried out to investigate the effects of contact time and dye concentration on biosorption efficiency. Maximum biosorption amounts were achieved almost in the 20-30 min of contact for the studied dye range (50-200 mg l ^-1). An increase in the dye concentration resulted in decrease in the percent dye removal and increase in the biosorption capacity of biosorbent. Different kinetic and isotherm models were used to examine the biosorption experimental data for elucidating the dye removal mechanism. The equilibrium data were best represented by Freundlich isotherm model confirming multilayer coverage. The kinetics of dye biosorption best obeyed the pseudo-secondorder equation. The negative value of standard Gibbs free energy change (-3.61 kJ mol^-1) indicated that physical forces were involved in the spontaneous dye biosorption. Thus, the sawdust as a possible non-conventional biosorbent presented an interesting option for bioremediation of contaminated environments by such unsafe dyes.     

Sorption properties of iron impregnated activated carbon web for removal of methylene blue from aqueous media

In this study, impregnation of iron chloride was carried out on needle punched web of waste acrylic fibers, which was subsequently carbonized under layer of charcoal by physical activation in high temperature furnace to produce iron impregnated activated carbon (FeAC). For comparison purpose, one more sample of activated carbon (AC) was prepared without impregnation of iron chloride. Both the webs were carbonized at 1200 °C with no holding time, and characterization of BET surface area, SEM morphology, EDX elemental analysis, XRD crystalline structure was performed. The FeAC web was used as adsorbent for the removal of methylene blue from aqueous solution. The dye removal percentage was investigated at different experimental parameters like different dye concentrations, adsorbent dosage, stirring speed and different pH. The obtained results were analyzed using linear and non-linear forms of Langmuir and Freundlich isotherms and adsorption kinetics (i.e. pseudo first order and pseudo second order model).     

Morphological structures of the cellulose hybrids containing polyhedral oligomeric silsesquioxane and their application for removing C.I. Reactive Red 250

Cellulose hybrids containing polyhedral oligomeric silsesquioxane (POSS) were synthesized by crosslinking reaction. The chemical and morphological structures of the hybrids were characterized by elemental analysis, infrared spectrum, scanning electron microscope and atomic force microscope. The hybrids were used for adsorbing C.I. Reactive Red 250 in aqueous solution. Adsorption kinetic and equilibrium isotherm of the cellulose hybrids for the dye were investigated. The hybrids formed new adsorptive positions for dyes because of a nanometer-sized cubic core and numerous organic functional groups (-C-N-). The adsorption capacity of the hybrid materials was significantly higher than that of the control cellulose. The adsorption of the dye on the hybrids was good fit with Langmuir isotherm equation and the second-order model. The apparent activation energy of the dye on the hybrid was 14.87 kJ/mol.     

Equilibrium and kinetic modeling of the adsorption of indigo carmine onto silk

Quantitative adsorption kinetic and equilibrium parameters for indigo carmine dyeing of silk were studied using UV-visible absorption spectroscopy. The effect of initial dye concentration, contact time, pH, material to liquor ratio (MLR), and temperature were determined to find the optimal conditions for adsorption. The mechanism of adsorption of indigo carmine dyeing onto silk was investigated using the pseudo first-order and pseudo second-order kinetic models. The adsorption kinetics was found to follow a pseudo-second-order kinetic model with an activation energy (E _a) of 51.06 kJ/mol. The equilibrium adsorption data of indigo carmine dye on silk were analyzed by the Langmuir and Freundlich models. The results indicate that the Langmuir model provides the best correlation. Adsorption isotherms were also used to obtain thermodynamic parameters such as free energy (ΔG ^o), enthalpy (ΔH ^o), and entropy (ΔS ^o) of adsorption. The negative values of ΔG ^o and Δ^{H o} indicate the overall adsorption process is a spontaneous and exothermic one.     

球状壳聚糖树脂对茶多酚的吸附热力学和动力学研究

采用反相悬浮交联法制备了球状壳聚糖树脂(RCM),通过静态吸附实验,研究了RCM对茶多酚的吸附热力学和动力学特性。结果表明:吸附等温线符合Laugmiur等温曲线,且平衡常数Kb随着温度升高而升高。吸附是非自发的、吸热的、熵增加的过程。吸附过程符合二级动力学吸附模型,吸附过程主要受粒子内扩散模型控制。     

Algal decolorization and degradation of monoazo and diazo dyes

This study is to inspect how the variation of molecular structures and functional groups present in our models, monoazo dye (Tartrazine) and diazo dye (Ponceau), affects decolorization capabilities of green algae, cyanobacteria and diatoms. The results revealed that the removal of azo dyes was rapid at the initial period of study (3 days) and became slowly with the time (6 days). The maximum decolorization was observed at 5 ppm Tartrazine with S. bijugatus (68%) and N. muscourm after 6 days incubation. The reduction of color removal appears to be related to the molecular structure of the dyes and species of algae used. The culture of the diatom Nitzschia perminuta was completely died after 2 days of incubation. Azo reductase of algae, which is responsible for degradation of azo dyes into aromatic amine by breaking the azo linkage, was estimated. IR spectra represented a new peak at 3300 cm(-1) and a reduction in the azo band at 1642-1631 cm(-1). In order to investigate the sorption behavior of algae, Langmuir equilibrium model was tested.     

Use of amino-modified cotton fibers loaded with copper ions for anionic dye removal under batch and fixed-bed systems: A comparative study

Amine-functionalized supports were prepared by chemical modification of cotton fibers using amino compounds namely diethylenetriamine (DET) and 1,4-diaminobutane (DB) in order to be loaded with copper ions. Evidence of attaching amine groups onto cellulosic fibers was confirmed through nitrogen and SEM analysis. Adsorption behavior of Acid Blue 25 from aqueous solutions onto [Cu(II)/DET-cotton] and [Cu(II)/DB-cotton] has been evaluated via batch and column mode systems. During the batch experiments, the effects of temperature and type of adsorbent on dye removal were investigated. Results revealed the formation of ternary complexes of the type [AB25/Cu(II)/adsorbent] with a [5/2:3:1] stoichiometry for DET-cotton and a [1:1:1] stoichiometry for DB-cotton at 20 °C. In the isotherm studies, Langmuir, Freundlich, and Jossens equations were applied and it was found that the experimental data conformed to Jossens model. Thermodynamic parameters such as change in free energy (ΔG ⁰), enthalpy (ΔH ⁰), and entropy (ΔS ⁰) have also been calculated in this paper, and it was found that the adsorption process was exothermic and spontaneous. The column experiments were conducted to study the effect of bed height on adsorption performance of both adsorbents. Results exhibited that the column capacity of [Cu(II)/DET-cotton] complex was found to be higher than that of [Cu(II)/DB-cotton] as was obtained in batch process. BDST model was applied to experimental data in order to predict the breakthrough curves and determine the characteristics parameters of the column useful for process design. Results revealed that the used model was appropriate to fit the experimental data. Desorption studies to recover the adsorbed dye from both adsorbents were performed with NaOH and NH₄Cl solutions.