Application of nanometer size of polypyrrole as a suitable adsorbent for removal of Cr(VI)

The objective of this work was to investigate the sorption characteristics of polypyrrole (PPy) for the removal of Cr(VI) from aqueous solutions. The sorption process was carried out by a dynamic batch method in order to determine the optimum conditions. For a sorbent dose of 0.6 g in 100 mL of a Cr(VI) solution, at a contact time of 15 min and a pH of 3, a removal efficiency of 84.5% was achieved. The Morris–Weber and Lagergren equations, as well as a pseudo‐second‐order equation were examined to explore the kinetics of the removal process. In addition, the Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models were applied to estimate the capacity, intensity, and energy of the sorption process. It was found that increasing temperature showed a positive effect on the ion sorption efficiency. In summary, PPy was shown to be a suitable candidate for chromium(VI) ion removal from aqueous solutions at different concentrations. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers.     

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.     

Application of kinetic,isotherm and thermodynamic models for the adsorption of Co(II) ions on polyaniline/polypyrrole copolymer nanofibers from aqueous solution

The aim of this research is to investigate sorption characteristics of polyaniline/polypyrrole copolymer nanofibers (PANI/PPy copolymer nanofibers) for the removal of Co(II) ions from aqueous solution. The adsorbent is characterized using FE-SEM, TEM, FTIR, TGA, DSC and BET surface area. The sorption of Co(II) ions by batch method is applied and the optimum conditions are investigated. In optimum condition, removal efficiency was 99.68% for 100 mg L⁻¹ Co(II) solution. It is found that temperature has a positive effect on the removal efficiency. It can be concluded that PANI/PPy copolymer nanofibers are potentially able to removal of Co(II) ions from aqueous solutions.     

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 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.     

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.     

Vapor‐phase polymerization of pyrrole on flexible substrate at low temperature and its application in heat generation

The vapor‐phase polymerization of pyrrole to form conducting polypyrrole (PPy) films was applied to coat flexible poly(ethylene terephthalate) (PET) fabrics. A PPy‐coated PET fabric surface resistance of 200–20 000 Ω□^?1 was obtained. The polymerization conditions, such as the concentration of oxidant and the reaction time and temperature, were systematically investigated. The coated fabric samples exhibited increasing temperatures when subjected to a fixed DC voltage. This result indicates the potential of these PPy‐coated fabric materials for heating applications. Copyright © 2009 Society of Chemical Industry     

Batch and fixed‐bed column adsorption of Cu(II), Pb(II) and Cd(II) from aqueous solution onto functionalised SBA‐15 mesoporous silica

Functionalised SBA‐15 mesoporous silica with polyamidoamine groups (PAMAM‐SBA‐15) was successfully prepared with the structure characterised by X‐ray diffraction, nitrogen adsorption–desorption, Fourier transform infrared spectra and thermogravimetric analysis. PAMAM‐SBA‐15 was applied as adsorbent for Cu(II), Pb(II) and Cd(II) ions removal from aqueous solution. The effects of the solution pH, adsorbent dosage and metal ion concentration were studied under the batch mode. The Langmuir model was fitted favourably to the experimental data. The maximum sorptive capacities were determined to be 1.74 mmol g^?1 for Cu(II), 1.16 mmol g^?1 for Pb(II) and 0.97 mmol g^?1 for Cd(II). The overall sorption process was fast and its kinetics was fitted well to a pseudo‐first‐order kinetic model. The mean free energy of sorption, calculated from the Dubinin–Radushkevich isotherm, indicated that the sorption of lead and copper, with E > 16 kJ mol^?1, followed the sorption mechanism by particle diffusion. The adsorbent could be regenerated three times without significant varying its sorption capacity. A series of column tests were performed to determine the breakthrough curves with varying bed heights and flow rates. The breakthrough data gave a good fit to the Thomas model. Maximum sorption capacity of 1.6, 1.3 and 1.0 mmol g^?1 were found for Cu(II), Pb(II) and Cd(II), respectively, at flow rate of 0.4 mL min^?1 and bed height of 8 cm, which corresponds to 83%, 75% and 73% of metallic ion removal, respectively, which very close to the value determined in the batch process. Bed depth service time model could describe the breakthrough data from the column experiments properly. © 2012 Canadian Society for Chemical Engineering     

Dielectric studies of composite paper reinforced with polypyrrole coated pulp fibers from wasted egg holders

Development of thin, flexible, light‐weight, renewable, low‐cost, and environmentally friendly electrode materials are highly feasible in era of modern disposable electronic technology. This article presents the synthesis and dielectric studies of polypyrrole (PPy) coated pulp fibers, directly collected from wasted egg holder's tray. PPy coated pulp fibers converted into compact sheet for the development of potential renewable and low‐cost electrode materials. The morphology, chemical structure, and thermal stability of naked and PPy coated pulp fibril sheets were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA), respectively. PPy coated pulp fibers revealed better thermal stability and compactness of sheet morphology. Impedance measurements showed a high value of dielectric constant of 1.15 × 10⁶ at 0.5 Hz and conductivity of 7.45 × 10^?4 S/cm at room temperature for PPy coated pulp fibril sheet. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42422.     

CuBr2‐induced charge screening on photoactive nanocolloidal polypyrrole:poly(styrene sulfonate) composite multilayer thin‐film counter electrodes for high‐efficiency dye‐sensitized solar cells

Nanocolloidal polypyrrole (PPy):poly(styrene sulfonate) (PSS) particles were synthesized by chemical oxidative polymerization using 15 wt% of PSS. The highly processable polymer composite (PPy:PSS) was spin‐coated at 4000 rpm on fluorine‐doped tin oxide glass and subsequently employed as a counter electrode (CE) for dye‐sensitized solar cells (DSCs). PPy:PSS multilayer (one, three, five) CEs were treated with CuBr₂ salt, which enhances the efficiency of the DSCs. Optical studies reveal that a bulkier counterion hinders interchain interactions of PPy which on salt treatment shows a moderate redshift in absorption maxima. Salt‐treated PPy:PSS films exhibit lower charge transfer resistance, higher surface roughness and better catalytic performance for the reduction of I₃^?, when compared with untreated films. The improved catalytic performance of salt‐treated PPy:PSS multilayer films is attributed to charge screening and conformational change of PPy, along with the removal of excess PSS. Under standard AM 1.5 sunlight illumination, salt treatment is shown to boost the efficiency of multilayer PPy:PSS composite film‐based DSCs, leading to enhanced power conversion efficiency of 6.18, 6.33 and 6.37% for one, three and five layers, respectively. These values are significantly higher (ca 50%) than those for corresponding devices without CuBr₂ salt treatment (3.48, 2.90 and 2.01%, respectively). © 2016 Society of Chemical Industry     

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.     

Fluoride Sorption from Aqueous Solutions and Drinking Water by Magnesium,Cobalt, and Nickel Hydrotalcite-Like Compounds in Batch and Column Systems

Magnesium, nickel, and cobalt hydrotalcite-like compounds (MgAlHT, NiAlHT, and CoAlHT) were used to remove fluoride ions from aqueous solutions and drinking water in batch and column systems. Mg, Ni, and Co hydrotalcite like compounds with similar M²⁺:Al³⁺ ratios were synthesized. F^? ions were determined in the remaining solutions using a fluoride ion selective electrode. Kinetic of the fluoride sorption from aqueous solutions by hydrotalcite-like compounds (HT) was best described by the pseudo-second-order model and the equilibrium was reached in less than 200 minutes for all cases (MgAlHT, NiAlHT and CoAlHT); however, this behavior was not observed for fluoride sorption from drinking water by NiAlHT. The sorption isotherms of the fluoride ion by hydrotalcite like compounds could be best fitted to the Langmuir and Freundlich models. NiAlHT showed the highest efficiency for the removal of fluoride ions from aqueous solutions in batch system. The removal of fluoride ions by NiAlHT from aqueous solutions was more efficient than from drinking water in both batch and column systems.     

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     

Laccase‐catalyzed synthesis of polypyrrole‐multiwalled carbon nanotube composites as energy storage materials for capacitors

Multiwalled carbon nanotubes (MWNTs) were coated with polypyrrole (PPy) using in situ enzymatic polymerization of pyrrole catalyzed by a laccase (benzenediol:oxygen oxidoreductase, EC 1.10.3.2) from Trametes versicolor. Transmission electron microscopy revealed that the MWNTs were uniformly coated with very thin layers of PPy without any indication of globular polymer aggregate formations. The enzymatic synthesis of the MWNTs/PPy composites was quite simple being performed in a one‐pot aqueous solution (pH 4.0) under mild reaction conditions. The potential of the composites with respect to the development of energy storage devices was demonstrated by fabricating a two‐electrode coin cell capacitor (diameter 20 mm, thickness 1.6 mm) utilizing the composites as electrode materials. The capacitance of the cell was 28.0 F g^?1 for the electrode material as measured by a galvanostatic charge–discharge method. The energy density and power density were 2.55 and 805 W kg^?1, respectively, which were close to those of the capacitors classified as ultracapacitors. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43307.     

Adsorptive removal of technetium‐99 using macroporous poly(GMA‐co‐EGDMA) modified with diethylene triamine

The possibility of sorption of technetium‐99 in the form of pertechnetate anion (TcO₄^?) and the sorption kinetics for removing TcO₄^? from aqueous solution by chelating polymers based on glycidyl methacrylate (GMA) were investigated. Two samples of macroporous crosslinked poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) (PGME), with different amount of the crosslinker (ethylene glycol dimethacrylate, EGDMA), were synthesized by suspension copolymerization and functionalized with diethylene triamine (deta). We propose that nonspecific sorption of pertechnetate anion via electrostatic interactions takes place at the protonated amino groups of macroporous crosslinked copolymer. The results of batch experiments performed at pH 1–14 showed fast sorption kinetics for removing TcO₄^? by amino‐functionalized PGME‐deta in a wide range of pH, that is, from 1.0 to 9.0. Almost complete removal of TcO₄^? (91–98%) was reached within 180 min in the stated pH range (1.0–9.0), with the sorption half‐times of under 25 min. The partitioning coefficients of linear adsorption isotherms, with 180‐min equilibrium time, reach the high values of 2130 mL g^?1 and 1698 mL g^?1 for the two samples of synthesized PGME‐deta. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of polyaniline nanocomposite and its application for chromium removal from aqueous solution

The aim of this research was to investigate the sorption characteristics of polyaniline coated on sawdust (PAn/SD) for the removal of Cr(VI) ions from aqueous solutions. The sorption of Cr(VI) ions was carried out by the batch method. Characterization of PAn/SD was done by FTIR and SEM. The optimum conditions of sorption were found to be a PAn/SD dose of 0.6 g in 100 mL of Cr(VI) solution (50 mg/L), a contact time of 20 min, pH 2, and a temperature of 20°C, Increased temperature had a negative effect on the removal efficiency. Three equations, that is Morris–Weber, Lagergren, and pseudo‐second‐order, were tested to track the kinetics of the removal process. The kinetic data indicated that the adsorption process was described by the Morris–Weber equation. The Langmuir, Freundlich, and Dubinin–Radushkevick models were used with sorption data to estimate sorption capacity, intensity, and energy. The data were fitted with the Freundlich model. The thermodynamic parameters ΔH, ΔS, and ΔG were evaluated. They showed that the adsorption of Cr(VI) onto PAn/SD was feasible, spontaneous, and exothermic under the studied conditions. For desorption of Cr(VI) adsorbed onto PAn/SD, aqueous NaOH was used; with it, 85% of the adsorbed Cr(VI) could be desorbed. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

Synthesis of Fe3O4/polyaniline nanocomposite and its application for nitrate removal from aqueous solutions

The aim of this work was to investigate the sorption characteristics of Fe₃O₄ coated on polyaniline (Fe₃O₄/PAn) for the removal of NO₃^? ions from aqueous solutions. The sorption of NO₃^? ions by the batch method was carried out. The optimum conditions of sorption were found to be a Fe₃O₄/PAn dose of 0.4 g in 100 mL of NO₃^? solution, a contact time of 10 min, pH and temperature 7 and 40°C, respectively. Temperature had a negative effect on the removal efficiency. Three equations, i.e., Morris–Weber, Lagergren, and pseudo‐second‐order, were tested to track the kinetics of the removal process. The Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models were subjected to sorption data in order to estimate sorption capacity, intensity, and energy. The thermodynamic parameters ΔH, ΔS, and ΔG were evaluated. They showed that the adsorption of NO₃^? onto Fe₃O₄/PAn was feasible, spontaneous, and exothermic under the studied conditions. It can be concluded that Fe₃O₄/PAn has potential to remove NO₃^? ions from aqueous solutions at different concentrations. The system Fe₃O₄/Pan was successfully tested for a high removal efficiency of NO₃^? from urban wastewater. J. VINYL ADDIT. TECHNOL., 19:147–156, 2013. © 2013 Society of Plastics Engineers     

The use of dyestuff-treated rice hulls for removal of heavy metals from waste water

Rice hulls, when coated with the reactive dye of Procion Red or Procion Yellow, was found to be highly effective for removal of many metal ions from aqueous solutions both in batch and column method. When 120–130 ppm solutions were used, quantitative removal could be achieved with Pb²⁺, Cd²⁺, and Hg²⁺. After the adsorption of metal ions, the substrate could be recovered almost completely by treating with dilute hydrochloric or nitric acid solution, and used repeatedly.     

Composite of cellulosic agricultural waste coated with semiconducting polypyrrole as potential dye remover

A composite was obtained from cellulosic agricultural waste material (Sorghum vulgare) coated with conducting polypyrrole by in situ polymerization using potassium persulfate as chemical oxidant. The composite was characterized by Raman spectroscopy, FTIR spectroscopy, scanning electron microscopy (SEM), and cyclic voltammetry. Aqueous adsorption experiments of methylene blue dye onto the obtained materials at different pH values were conducted. The results showed that this composite is an efficient sorbent for dye removal. The adsorption mechanism was well described by the Langmuir isotherm. The adsorption capacity at neutral pH for uncoated sorghum at an equilibrium concentration (C_e) of methylene blue dye of 10 mg/l was 41.6 mg of dye/g of sorghum and for sorghum/PPy composite was 68.4 mg of dye/gram of composite, which is 1.6 times higher; however, the maxima adsorption capacities were 86.2 and 94.4 mg/g, respectively (only 9.5% more than the uncoated sorghum). It was also observed that at acidic pH for a C_e of 10 mg/l the adsorption capacity of composite was 79.2 mg of dye/gram of composite and the maximum adsorption capacity was 143.5 mg/g (66.4% more than the uncoated sorghum). SEM analysis showed homogeneous coating of cellulosic sorghum material with PPy. Conductivity value of composite was 13.0 × 10⁻³ S/m. Fabrication of this composite should significantly diminish the cost of dye removal from aqueous solutions with respect to some commercial adsorbents. POLYM. COMPOS., 35:186–193, 2014. © 2013 Society of Plastics Engineers     

Removal of phosphate anions from aqueous solutions using polypyrrole‐coated sawdust as a novel sorbent

This work was focused on the removal of phosphate ions using polypyrrole‐coated sawdust as a novel cost‐effective sorbent. The phosphate uptake followed the Langmuir sorption isotherm, and the sorption capacity at 20, 35, and 50°C was found to be 17.33, 23.41, and 30.39 mg/g, respectively; this indicated favorable sorption at higher temperatures. The kinetic uptake data were modeled with the Lagergren equation, first‐order and second‐order kinetic models, and the simple Elovich model. The results indicated that the Lagergren model best described the uptake data. The intraparticle diffusion coefficient, as determined for 250–211‐ and 630–600‐μm sorbent particles at 20°C, was found to be 287.3 × 10^?2 and 228.3 × 10^?2 mg g^?1 min^?1, respectively. The intraparticle diffusion was also confirmed with the Bangham equation. The sorption mean free energy, calculated with the Dubinin–Radushkevich equation, was found to be 10.98 kJ/mol, thus confirming an ion‐exchange regulated sorption process. The positive value of the enthalpy change (i.e., 4.23 kJ/mol) confirmed the endothermic nature of the sorption process. The negative values of the change in the standard free energy were indicative of the spontaneous nature of the sorption process. Finally, the activation energy of the sorption process for 250–212‐μm particles, determined with the Arrhenius equation, was found to be 41.68 J/mol. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009