Application of polyaniline nanolayer composite for removal of tartrazine dye from aqueous solutions

In this research, polyaniline was synthesized chemically onto the surface of sawdust as a thin layer (termed as PAni/SD) and was then used for removal of tartrazine dye (a typical anionic azo dye) from aqueous solutions. Ammonium peroxodisulphate was used as chemical oxidant for polymerization of polyaniline directly on the surface of sawdust. The procedure involves sorption experiments were performed on both batch and column systems. The effects of some important parameters such as pH, initial concentration, sorbent dosage, exposure time and temperature on uptake of tartrazine dye were investigated. Adsorption studies have shown that pH of the tartrazine solution has influence on the dye removal capacity of PAni/SD. It was found that effective dye removal is occurred under neutral or acidic conditions. The treatments of the data were carried out using both Freundlich and Langmuir adsorption isotherms. Sorption/desorption studies showed that PAni/SD was fast, simple, inexpensive, highly efficient and potential re-usable adsorbent to remove tartrazine from aqueous solutions. Based on our kinetics and thermodynamic studies, it was found that sorption process was endothermic (ΔH > 0) and the experimental data fitted very well with pseudo second-order kinetic model.     

Synthesis and intercalation of silver nanoparticles in kaolinite/DMSO complexes

Ag nanoparticles were synthesized in the interlamellar space of a layered kaolinite. Disaggregation of the lamellae of the nonswelling kaolinite was achieved by the intercalation of dimethyl sulfoxide (DMSO). The kaolinite was suspended in aqueous AgNO₃ solution and the adsorbed Ag⁺ ions were reduced on the surface of kaolinite lamellae with NaBH₄ or UV light irradiation. The silver nanoparticles formed were characterized by X-ray diffraction (XRD), small angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). We studied the effects of the two reduction methods on the size and the size distribution of Ag nanoparticles and how clay mineral structure is altered as a consequence of particle formation. It was established that the size of Ag nanoparticles depends on both silver content and the reduction method. Photoreduction of silver led to the formation of relatively large Ag nanoparticles (diameter 8–14 nm).     

Synthesis,characterization and adsorption studies of h-BN crystal for efficient removal of Cd2+ from aqueous solution

In the present study, hexagonal boron nitride (h-BN) was synthesized from boric acid and melamine by thermal annealing method in a nitrogen atmosphere. The pure h-BN was used as an efficient sorbent for the uptake of Cd²⁺ ions from the solution phase. The kinetics and sorption studies of metal ions onto the h-BN were carried out in batch adsorption experiments at different temperature, time, pH, sorbent dosage, and concentration of metal ions. The optimum pH for the removal of the Cd²⁺ ions was found to be pH 7. The effect of temperature showed that the process of Cd²⁺ sorption remained endothermic in the range of 298 K–328 K. The Lagergren's first and Ho's second kinetic models were tested to interpret the adsorption kinetic data, however the present data was explained well by Ho's model for kinetics. The thermodynamic perameters ΔG, ΔS and ΔH were determined using the available adsorption data at different temperatures. The physicochemical properties of the synthesized product were also characterized before and after adsorption by different analytical techniques like FT-IR, TGA, XRD and Point of Zero Charge (PZC). The morphology of the surface was analyzed with the help of Scanning Electron Microscopy. The h-BN proved to be an efficient adsorbent for the uptake of the Cd²⁺ ions from aqueous media.     

Application of hydrophilic finished of synthetic fabrics coated with CMC/acrylic acid cured by electron beam irradiation in the removal of metal cations from aqueous solutions

Modified textile fabrics were used to remove Cu⁺² and Cr⁺³ ions from aqueous solutions. For this purpose, modified Nylon‐6, polyester woven and knitted fabrics were prepared by coating the surface with a thin layer of aqueous solution of carboxymethyl cellulose (CMC) and acrylic acid (AAc) of thickness 25 μm. Radiation crosslinking of the coated layer was carried out by electron beam irradiation with a constant dose of 30 kGy. Morphology of the coated fabrics was examined by scanning electron microscope (SEM) which indicated the compatibility between the coated layer and fabrics. Properties attributed to the hydrophilicity, especially water uptake and weight loss before and after several washing cycles were followed up. The effect of AAc concentration on the hydrophilic properties of the coated fabrics was studied. A considerable enhancement in water uptake has been attained on increasing AAc content in solution in case of nylon‐6 followed by polyester woven followed by polyester knitted fabrics. The performances of the modified textile fabrics were evaluated for the recovery of Cu⁺² and Cr⁺³ from aqueous solution. The metal ion absorption efficiency of the modified textile fabrics was measured using UV Spectrophotometer analysis and EDX. Parameters affecting the efficiency of these textile fabrics in the removal of metal ions from aqueous solution namely, concentration of AAc and the immersion time were studied. It was found that there was a marked increase in the recovery of metal ions on increasing both immersion time and concentration of AAc. This study evidences that the modified textile fabrics can be used for the purpose of removal of some heavy metals such as Cu and Cr. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Selective recovery of silver ions from aqueous solutions using modified silica beads with Adogen 364

In this work, a method to prepare new adsorbents for the recovery of silver ions was studied. Cheap silica beads for industrial use were obtained and silanized with dichlorodimethylsilane after pretreatment with hot water to increase the silanol contents, followed by immobilization of Adogen 364 (a mixture of trialkyl tertiary amines, Witco Co), a commercial solvent extractant that has a good affinity with silver ions. This sample, designated as K2WDA, was proven to be effective for the adsorption of silver ions from aqueous solutions with fast adsorption rates where sodium nitrate was added as a complexation agent to increase the adsorption capacity of the basic extractant. The adsorption capacity of K2WDA at pH 5 was 0.125 mmol g^?1 and corresponded to the proposed mechanism that silver ions adsorb on the functional group with a 1:1 molecular ratio. Selectivity for silver ions in synthetic plating wastewater containing Cu²⁺ and Ni²⁺ ions was excellent due to thermodynamic stability. In addition, 80% of the silver ions adsorbed could be recovered with sodium thiosulfate solution rather than acids and the solution was concentrated more than 10 times compared with the original solution. For practical application, a semi‐batch reactor was considered and numerical modeling was performed. © 2002 Society of Chemical Industry     

Impregnated of C6CoFeN6 nanoparticles in poly-1-naphthol for uptake of Cs(I) from aqueous waste

To carry out our research, C₆CoFeN₆@poly-1-naphthol nanoparticles were synthesized and characterized by SEM, X-ray diffraction, Fourier transform infrared, thermogravimetric analysis and Brunauer–Emmett–Teller (BET) analyses. The SEM images indicate that the average particle sizes are about 60 nm in diameter. The BET result provides a clear evidence for the high surface area of the sample 180.6 m²/g. Cs(I) ions removed from the aqueous solution in a batch mode using CoHCF@poly-1-nanphtol as an adsorbent. The adsorption effecting parameters such as the solution pH, initial Cs(I) concentration, contact time and temperature were studied. Maximum sorption capacity for the nanocomposite was found to be 200.5 mg/g at 1000 mg/g, pH = 5 and 298 K. The time-adsorption dependence studies indicated that the maximum Cs(I) uptake was within the initial 40 min contact time and the adsorption mechanism was governed by the double exponential model. The equilibrium sorption data fitted well to the Freudlich model with n ? 1 indicating a stronger interaction and high affinity of C₆CoFeN₆@poly-1-naphthol for Cs(I) ions. The thermodynamic parameters, including changes in Gibbs free energy, entropy and enthalpy, were determined. The results indicated that CoHCF–poly-1-nanphtol could be a potential adsorbent for the uptake of Cs(I) ions from an aqueous solution.     

Study on the synthesis,characterization, and sorption of some metal ions on gelatin‐ and acrylamide‐based hydrogels

Graft copolymers and networks of gelatin were synthesized with three acrylamides (acrylamide, 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid, and N‐iso‐propylacrylamide) by using a redox initiator system consisting of ammonium peroxysulfate–ferrous ammonium sulfate in either the absence or the presence of a crosslinker (N,N‐methylene bisacrylamide) at two temperatures. Characterization of synthesized polymers was studied by FTIR and thermal studies to investigate evidence of grafting or interpenetrating network formation and to investigate the effect of reaction conditions and crosslinker concentration on the properties of synthesized polymers. Detailed investigation into water‐uptake properties of these hydrogels was carried out as a function of time, temperature, and pH. The inherent properties of the monomer incorporated onto gelatin collectively act as determinant of the water‐absorption behavior of the hydrogels. Sorption of Fe⁺², Cr⁺⁶, and Cu⁺² ions from their aqueous solutions was also studied on select hydrogels, where it was observed that metal ions are sorbed by effective partitioning between hydrogels and solution phase and apart from the nature of metal ions, and structural aspects of hydrogels also determine the quantum of metal ion uptake. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3856–3871, 2003     

Highly Efficient Adsorption of Anionic Dyes from Aqueous Solutions Using Sawdust Modified by Cationic Surfactant of Cetyltrimethylammonium Bromide

In the present study, the adsorption behavior of Congo Red (CR) dye from aqueous systems onto sawdust modified by cetyltrimethylammonium bromide, CH₃(CH₂)₁₅N(CH₃)₃Br (CTAB) was attempted. Adsorption experiments were carried out using both batch and column modes under various operating conditions. The effects of some important parameters such as solution pH, adsorbent dosage, initial dye concentration and contact time were investigated. Treatment of the equilibrium data obtained in batch experiments was carried out using Langmuir and Freundlich isotherm equations. Based on the isotherm analysis, it was found that the adsorption of CR dye onto SD fits well to the Langmuir model and the adsorption pattern on CTAB modified sawdust (CTAB/SD) followed the Freundlich isotherm which is indicative of heterogeneity of the adsorption sites on the surfactant-modified sawdust. The maximum adsorption capacity of SD and CTAB/SD were found to be 5.2 and 9.1?mg?g^?1, respectively, according to the Langmuir model. However, much higher differences in sorption capacities were observed for CTAB/SD and SD in the column system (66.73?mg?g^?1). In order to find out the possibility of the exhausted column for frequent use, a regeneration study was also carried out. It was found that the dye uploaded column can be easily regenerated with a high performance using ethanol as the washing solution.     

Electron Beam Grafted Polymer Adsorbent for Removal of Heavy Metal Ion from Aqueous Solution

Abstract

An electron beam grafted adsorbent was synthesized by post irradiation grafting of acrylonitrile (AN) on to a non‐woven thermally bonded polypropylene (PP) sheet using 2 MeV electron beam accelerator. The grafted poly(acrylonitrile) chains were chemically modified to convert a nitrile group to an amidoxime (AMO) group, a chelating group responsible for metal ion uptake from an aqueous solution. The effect of various experimental variables viz. dose, dose rate, temperature, and solvent composition on the grafting extent was investigated. PP grafted with the amidoxime group (AMO‐g‐PP) was tested for its suitability as an adsorbent for removal of heavy metal ions such as Co²⁺, Ni²⁺, Mn²⁺, and Cd²⁺ from aqueous solution. Langmuir and Freundlich adsorption models were used to investigate the type of adsorption of these ions. The adsorption capacities of the adsorbent for the metal ions were found to follow the order Cd²⁺>Co²⁺>Ni²⁺>Mn²⁺. The kinetics of adsorption of these ions indicated that the rate of adsorption of Cd²⁺ was faster than that of other ions studied.     

Application of polypyrrole coated onto wood sawdust for the removal of carmoisine dye from aqueous solutions

In this research, the removal of carmoisine dye from aqueous solutions using polypyrrole coated onto sawdust (PPy/SD) has been investigated. The sorption experiments were performed using both batch and column systems. The effects of some important parameters such as pH, initial concentration, sorbent dosage, exposure time, and temperature on uptake of carmoisine dye were investigated. Based on the data obtained in batch system, it was found that maximum adsorption is occurred under acidic conditions. Complete removal was observed when a dye solution with the initial concentration of 100 mg L^?1 was treated by 1.0 g of the used adsorbent (PPy/SD) at pH value of 4 and room temperature. However, higher sorption was observed at elevated temperature. According to the kinetics study, it was found that the experimental data fitted very well the pseudo‐second‐order kinetic model (k₂ = 0.184 g mg^?1 min^?1). It was found that polypyrrole chemically coated on SD is an efficient system for the removal of carmoisine dye from aqueous solutions. Desorption of the dye‐loaded column was also possible by using dilute NaOH solution with high efficiency (～ 80%). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Removal of Ce(IV) Ions from Aqueous Solutions Using Sawdust Coated by Electroactive Polymers

In this work, adsorption of the Ce(IV) ions onto polypyrrole (PPy) and polyaniline (PAn) conducting electroactive polymers as coated form on sawdust has been investigated. The effect of some important parameters such as initial concentration of the Ce(IV) ion adsorbent dosage, and contact time was studied. The experiments were carried out using both batch and column systems at room temperature. The equilibrium adsorption capacity of sawdust coated by polypyrrole and polyaniline for the removal of Ce(IV) ion was measured and extrapolated using linear Freundlich and Langmuir isotherms. It was found that sawdust modified by PPy and PAn improved the removal efficiency of Ce(IV) ions from aqueous solutions greatly.     

Separation and Recovery of Silver(I) Ions from Base Metal Ions by Melamine‐formaldehyde‐thiourea (MFT) Chelating Resin

Abstract

Melamine‐formaldehyde‐thiourea (MFT) chelating resin were prepared using melamine (2,4,6‐triamino‐1,3,5‐triazine), formaldehyde, and thiourea and this resin has been used for separation and recovery of silver(I) ions from copper(II) and zinc(II) base metals and calcium(II) alkaline‐earth metal in aqueous solution. The MFT chelating resin was characterized by elemental analysis and FT‐IR spectra. The effect of pH, adsorption capacity, and equilibrium time by batch method and adsorption, elution, flow rate, column capacity, and recovery by column method were studied. The maximum uptake values of MFT resin were found as 60.05 mg Ag⁺/g by batch method and 11.08 mg Ag⁺/g, 0.052 mg Zn²⁺/g, 0.083 mg Cu²⁺/g and 0.020 mg Ca²⁺/g by column method. It was seen that MFT resin showed higher uptake behavior for silver(I) ions than base and earth metals due to chelation.     

Preparation and Characterization of Gelatin Nanofibers Containing Silver Nanoparticles

Ag nanoparticles (NPs) were synthesized in formic acid aqueous solutions through chemical reduction. Formic acid was used for a reducing agent of Ag precursor and solvent of gelatin. Silver acetate, silver tetrafluoroborate, silver nitrate, and silver phosphate were used as Ag precursors. Ag⁺ ions were reduced into Ag NPs by formic acid. The formation of Ag NPs was characterized by a UV-Vis spectrophotometer. Ag NPs were quickly generated within a few minutes in silver nitrate (AgNO₃)/formic acid solution. As the water content of formic acid aqueous solution increased, more Ag NPs were generated, at a higher rate and with greater size. When gelatin was added to the AgNO₃/formic acid solution, the Ag NPs were stabilized, resulting in smaller particles. Moreover, gelatin limits further aggregation of Ag NPs, which were effectively dispersed in solution. The amount of Ag NPs formed increased with increasing concentration of AgNO₃ and aging time. Gelatin nanofibers containing Ag NPs were fabricated by electrospinning. The average diameters of gelatin nanofibers were 166.52 ± 32.72 nm, but these decreased with the addition of AgNO₃. The average diameters of the Ag NPs in gelatin nanofibers ranged between 13 and 25 nm, which was confirmed by transmission electron microscopy (TEM).     

Effect of sawdust surface treatment and compatibilizer addition on mechanical behavior,morphology, and moisture uptake of polypropylene/sawdust composites

Polypropylene/sawdust composites were investigated to assess the effect of sawdust surface treatment and compatibilizer addition on polymer/fiber adhesion. Two silane coupling agents were used for sawdust surface treatment: vinyl‐tris (2‐methoxyethoxy) silane and (3‐aminopropyl)triethoxysilane. Maleic anhydride grafted polypropylene was used as compatibilizer. Composites were prepared in a corotating twin‐screw extruder coupled to a Haake torque rheometer and submitted to tensile and bending tests as well as scanning electron microscopy (SEM). Moisture uptake tests were also performed. Results showed that incorporation of untreated sawdust to polypropylene (PP) caused reduction in composite tensile strength and increase in stiffness. When the only treatment used was surface modification with silane coupling agents, no significant changes were observed in mechanical properties. However, when compatibilizer was added to the composites, tensile strength was increased, and % elongation at break reduced, indicating improved system compatibility. The composite presenting the highest increase in tensile strength was that containing sawdust treated with amino silane in addition to the compatibilizer. SEM analyses corroborated the mechanical property results. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

A model for the electrical double layer combining integral equation techniques with quantum density functional theory

We have complemented the singlet reference interaction site model for the electric double layer by quantum chemical calculations for the interaction of ions and solvents with an electrode. Specific calculations have been performed for an aqueous solution of NaCl in contact with a Ag(1 1 1) electrode. The particle profiles near the electrode show the specific adsorption of Cl⁻ ions, but not of Na⁺, and are at least in qualitative agreement with those obtained by molecular dynamics. Including the electronic response of the silver surface into the model results in reasonable capacity–charge characteristics.     

Unravel the potential of zinc oxide nanoparticle-carbonized sawdust matrix for removal of lead(Ⅱ) ions from aqueous solution

Zinc oxide nanoparticles(ZnOnp) are molecular nanoparticles synthesized by a chemical precipitation method from zinc nitrate tetrahydrate and sodium hydroxide.Carbonized sawdust(CSD) was prepared from sawdust obtained from a local wood mill.The matrix of both provides a better material as an adsorbent.The present study applied the functionality of ZnOnp,CSD,and ZnOnp-CSD matrix as adsorbent materials for the removal of Pb(Ⅱ) ions from aqueous solution.The method of batch process was employed to investigate the potential of the adsorbents.The influence of pH,contact time,initial concentration of adsorbate,the dosage of adsorbents,and the temperature of adsorbate-adsorbent mixture on the adsorption capacity were revealed.The adsorption isotherm studies indicate that both Freundlich and Langmuir isotherms were suitable to express the experimental data obtained with theoretical maximum adsorption capacities(q_m) of 70.42,87.72,and 92.59 mg·g~(-1) for the adsorption of Pb(Ⅱ) ions onto ZnOnp,CSD,and ZnOnp-CSD matrix,respectively.The separation factors(R_L) calculated showed that the use of the adsorbents for the removal of Pb(Ⅱ) ions is a feasible process with R_L 1.The thermodynamic parameters obtained revealed that the processes are endothermic,feasible,and spontaneous in nature at 25-50℃.Evaluation of the kinetic model elected that the processes agreed better with pseudo-second order where the values of rate constant(k_2) obtained for the adsorption of Pb(Ⅱ) ions onto ZnOnp,CSD,and ZnOnp-CSD matrix are 0.00149,0.00188,and 0.00315 g·mg~(-1)·min~(-1),respectively.The reusability potential examined for four cycles indicated that the adsorbents have better potential and economic value of reuse and the ZnOnp-CSD matrix indicates improved adsorbent material to remove Pb(Ⅱ) ions from aqueous solution.     

Adsorption of lanthanum by magnetic alginate‐chitosan gel beads

BACKGROUND: The risk of environmental pollution is aggravated by the increasing application of considerable amounts of rare earth elements in advanced materials. This paper reports the preparation of novel magnetic alginate–chitosan gel beads and their application for adsorption of lanthanum ions from aqueous solution. RESULTS: Stable magnetic alginate–chitosan gel beads with average diameter 0.85 ± 0.05 mm were prepared by loading iron oxide nanoparticles onto a combined alginate and chitosan absorbent. The performance of the prepared beads for the adsorption of lanthanum ions from aqueous solution was tested. It was found that various parameters, such as aqueous pH, contact time, metal ion concentration, ion strength and temperature, have an effect on the adsorption. Adsorption equilibrium was reached in 10 h and the maximum uptake capacity was 97.1 mg g^?1. From the analysis of pH, FTIR and XPS data, it is proposed that lanthanum adsorption proceeds through mechanisms of cation exchange, electrostatic interaction and surface complexation, with the oxygen atoms the main binding sites. In addition, lanthanum ions could be selectively separated from coexisting base metal ions such as Pb (II), Cd (II), Co (II), Ni (II) and Cu (II) in the aqueous solution. CONCLUSION: The prepared magnetic alginate–chitosan gel beads exhibit high uptake capacity and selectivity for lanthanum sorption, and thus can be used for adsorptive recovery of lanthanum from aqueous solutions. Copyright © 2010 Society of Chemical Industry     

Application of polypyrrole coated on wood sawdust for removal of Cr(VI) ion from aqueous solutions

In this study polypyrrole (PPy) was synthesised chemically on the surface of sawdust that has already been soaked with monomer solution (pyrrole). FeCl₃ were used as chemical oxidants for oxidation of pyrrole into polymer (PPy/Cl). The sawdust coated by PPy (PPy/SD) was used as an efficient sorbent for removal of Cr(VI) ion from aqueous solutions. It was found that PPy/SD is very easy and simple to prepare and can be used as an effective sorbent for removal of Cr(VI) from water and wastewater solutions. The Cr(VI) removal is assumed to be mainly due to the anion exchange properties of the polymer which is formed as PPy⁺/Cl⁻. The introduced sorbent in this paper shows that PPy/SD can be used to eliminate or separate anionic contaminations from aqueous solutions under open circuit conditions.     

Removal of lead ions using phosphorylated sawdust

To increase the uptake capacity of lead ions, surface of sawdust were modified into phosphate groups. The phosphorylated sawdust prepared through chemical reaction with H₃PO₄ (85%) showed a high uptake capacity of about 1.45 mmol Pb/g-dry mass at pH 4. The component of phosphorylated sawdust was analyzed by EDX (energy dispersive X-ray) and the increase of phosphate group was confirmed. The phosphorylated sawdust had a high uptake capacity at low temperature of 10 °C and could remove lead ions of about 98% with 0.04 g of modified sawdust. Also, most of adsorption of lead ions was completed within 40 min.     

Application of Nano Surfactant Modified Biosorbent as an Efficient Adsorbent for Dye Removal

In the current study, sorption of methylene blue dye (MB) from aqueous solutions, using sawdust modified with sodium dodecyl sulfate (SDS/SD) has been investigated. Sorption experiments were performed using batch and fixed-bed column systems. The effects of important parameters, such as pH, initial dye concentration, flow rate, and bed depth on the sorption of MB dye have been studied. Thomas and the bed-depth service time model (BDST) were applied for analysis of sorption data and estimating of sorption capacity. In order to drive adsorption isotherms, sorption experiments were conducted in batch mode and the treatment of the obtained data were carried out using the Langmuir and Freundlich equations. Based on the breakthrough analysis obtained from continuous sorption experiments, the highest column capacity of 129.68 mg g^?1 was obtained for the SDS/SD adsorbent. The results of this study indicated that surfactant-modified sawdust is much more effective for basic MB dye removal compared to untreated sawdust (SD) and the exhausted SDS/SD column can be easily regenerated using dilute HCl solution with high performance (>95%). The results of this study also indicated the successful applicability of the introduced adsorbent as a very efficient and cost effective adsorbent for the removal of cationic dye molecules from aqueous wastes.