A semi-conducting polypyrrole/coffee grounds waste composite for rhodamine B dye adsorption

A composite based on coffee grounds waste (CGW) coated with the semi-conducting polypyrrole (PPy) was prepared by pyrrole polymerization using potassium persulfate as oxidant. The composite was characterized by FTIR spectroscopy, cyclic voltammetry, UV/vis spectroscopy, scanning electron microscopy (SEM) and TGA analysis. SEM analysis showed homogeneous coating of coffee fibers with spherical nanoparticles of PPy with diameters in the range of 200–300 nm. Aqueous adsorption experiments of rhodamine B dye (RhB) onto the as-prepared composite were performed. The effect of pH and initial dye concentration (C₀) on the adsorption behavior was studied. The results showed that this material was an efficient adsorbent of RhB dye at alkaline pH. The adsorption experiments were set at C₀ = 200 mg/L and initial pH values of 2.0, 3.25 and 9.0, the adsorption capacities were 7.22, 13.8, and 19.0 mg of dye/g of the composite, respectively. Nonetheless, when pH was maintained at 9.0 throughout adsorption time, the adsorption capacity increased to 32 mg of dye/g of the composite. When performing adsorption tests using pure CGW, dye adsorption was insignificant at any pH level. Adsorption isotherm for RhB at controlled pH of 9.0 was well described by the Redlich–Peterson model and by the typical Langmuir adsorption model with a theoretical maximum adsorption capacity (q_max) of 50.59 mg of dye/g of composite.     

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     

染料掺杂聚吡咯复合材料的研究进展

介绍了聚吡咯制备方法及掺杂剂种类,主要综述了使用不同染料作为掺杂剂制备聚吡咯对其形貌和性能的影响,指出了目前染料掺杂聚吡咯复合材料的研究现状,并对其发展进行了展望。     

Microwave-enhanced formation of glucose from cellulosic waste

The conversion of cellulose and cellulosic waste to fermentable sugars has been successfully demonstrated. Using a novel microwave intensified hydrothermal depolymerisation of cellulosic materials in liquid hot water, at pressures below 300 psi, conversions of up to 40% of fermentable sugars were obtained with limited by-product formation. A high selectivity for glucose over other sugars has been observed. Temperature is the crucial parameter as limited conversion is observed below 180 °C and optimum conversion is attained around 220 °C.     

Photoelectronic and transport properties of polypyrrole doped with a dianionic dye

Polypyrrole (PPy) doped with dodecylsulfate (DS) and an organic dye (indigo carmine, IC) was electrochemically prepared and characterized by Raman spectroscopy and X-ray diffraction (XRD). The photoelectrochemical properties of PPy-DS and PPy-DS-IC in contact with an electrolytic solution containing a redox couple were studied using the theories for the semiconductor ∣ electrolyte interface. Results indicate that the system containing IC presents a higher photocurrent density under polychromatic illumination and faster response time when compared with PPy-DS. This fact was assigned to the formation of molecular-scale paths in PPy-DS-IC. The IC molecules lying perpendicularly between PPy chains, as confirmed by the X-ray analysis, could facilitate the mass transport at the interface and increase the ordering degree to provide better electronic charge transfer in the bulk. Although the photoelectrochemical devices presented here do not present all the properties of inorganic-based devices, we discuss some strategies to enhance the photoelectrochemical properties and response time of conducting polymers used in these type of systems.     

Electrochemical properties of electrospun PAN/MWCNT carbon nanofibers electrodes coated with polypyrrole

The multi-walled carbon nanotube (CNT)-embedded activated carbon nanofibers (ACNF/CNT) and activated carbon nanofibers (ACNF) were prepared by stabilizing and activating the non-woven web of polyacrilonitrile (PAN) or PAN/CNT prepared by electrospinning. Both ACNF and ACNF/CNT were partially aligned along the winding direction of the drum winder. The average diameter of ACNF was 330 nm, while that of ACNF/CNT was lowered to 230 nm with rough surface. This was attributed to the CNT-added polymer solution in the electrospinning process providing finer fibers by increasing the electrical conductivity compared with the CNT-free one. The specific surface area and electrical conductivity of ACNF were 984 m²/g and 0.42 S/cm, respectively, while those of ACNF/CNT were 1170 m²/g and 0.98 S/cm, respectively. PPy was coated on the electrospun ACNF/CNT (PPy/ACNF/CNT) by in situ chemical polymerization in order to improve the electrochemical performance. The capacitances of the ACNF and PPy/ACNF electrodes were 141 and 261 F/g at 1 mA/cm², respectively, whereas that of PPy/ACNF/CNT was 333 F/g. This improvement in capacitance was attributed to the following: (i) the preparation of aligned nano-sized ACNF/CNT by electrospinning and the addition of CNT and (ii) the formation of a good charge-transfer complex by the PPy coating on the surface of the aligned nano-sized ACNF/CNT. The former leads to a good morphology and superior properties, such as a higher surface area, the formation of mesopores and an increase in electrical conductivity. The latter offers a refined three-dimensional network due to the highly porous structure between ACNF/CNT and PPy.     

Benign enzymatic synthesis of multiwalled carbon nanotube composites uniformly coated with polypyrrole for supercapacitors

BACKGROUND: Recently, various composites of carbon nanomaterials and conducting polymers have been actively investigated as potential electrode materials for supercapacitors which can store and deliver large amounts of electrical energy promptly. Harsh chemical or complex electrodeposition methods have been studied to prepare such composites. In this report, the mild and simple enzymatic catalysis of horseradish peroxidase (EC 1.11.1.7) in aqueous solutions (pH 4.0) was utilized for the first time to prepare composites of multiwalled carbon nanotubes and polypyrrole. RESULTS: Electron micrographs show that in situ enzymatic reaction by horseradish peroxidase enables the uniform coating of multiwalled carbon nanotubes with polypyrrole without containing the polymer aggregates. The specific capacitance of the composites (46.2 F g^?1) measured with a two‐electrode cell containing an electrolyte of 1 mol L^?1 NaNO₃ increased more than four‐fold compared with that obtained with bare multiwalled carbon nanotubes (10.8 F g^?1). CONCLUSIONS: Horseradish peroxidase‐catalyzed in situ synthesis of the composites of multiwalled carbon nanotubes and polypyrrole requires neither the derivatization of multiwalled carbon nanotubes and/or pyrrole monomers nor the post‐doping of the synthesized composites to enhance the capacitance of the composites. © 2012 Society of Chemical Industry     

农林废弃物吸附脱除废水中重金属研究进展

含重金属的工业废水对环境的危害是相当巨大的,生物吸附法可有效去除废水中的重金属.本文总结了常见的农林废弃物和化学改性剂在吸附重金属方面的研究现状,指出了生物吸附的影响因素及吸附工艺优化,阐述了生物吸附法的吸附机理及解吸处理,介绍了生物吸附的热力学和动力学模型及相关参数,同时指出了生物吸附法存在的问题,并展望其未来的发展前景.农林废弃物具有来源广、成本低、可再生等优点,用于重金属废水处理时,可实现资源的综合利用,具有良好的工业前景.     

Structural,electrical, and electromagnetic properties of cotton fabrics coated with polyaniline and polypyrrole

In this study, the structural, electrical, and electromagnetic properties of cotton fabrics coated with polyaniline (PAni) and polypyrrole (PPy) were investigated and compared. For the aims, anilin and pyrrole were used as monomers, and in situ polymerization on cotton fabric by chemical oxidative polymerization was performed. After production, the structural properties of the fabrics were determined with Fourier transform infrared spectroscopy and X‐ray diffraction. In addition, ultraviolet (UV) permeability, tensile strength, colorfastness, and electrical and electromagnetic measurements of the fabric samples were carried out. The resistance values of the cotton fabrics coated with PAni and PPy were found to be 350 and 512 Ω, respectively. The average electromagnetic shielding efficiency and average absorption values of the cotton fabrics coated with PAni were determined to be 3.8 dB and 48%, respectively, and these values for the cotton fabrics coated with PPy were 6 dB and 50%, respectively. Consequently, a significant difference was not observed between the resistance values and electromagnetic parameters of the fabrics coated with PAni and PPy, although the intact textile characteristics of the fabric coated with PPy were protected and improved, whereas the characteristics of the fabric coated with PAni were inferior. Moreover, we first report that the fabrics coated with conductive polymers had excellent UV‐protection properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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.     

Relationship between cellulase treatment and the dyeability with a direct dye for various kinds of cellulosic fibers

The cellulosic fibers were dyed to equilibrium with Congo Red before and after cellulase treatment. The fibers examined were rayon, polynozic, cupra, flax, and cotton. It was found that the volume term for dyeing (V) was associated with weight loss (WL) caused by the cellulase treatment, for the original fibers. Apparent affinity for dyeing (AF) for the cellulase-treated fibers was calculated using a constant value of V obtained for each kind of the original fibers. The results led to the assumption that there would be two kinds of the regions that could be accessible to dye. One would be the region that was readily digested by the enzymatic hydrolysis. The other would be the region that was additionally developed by the attack of cellulase. The previously dyed fibers were hydrolyzed by cellulase. It was found that the physical bondings that formed between cellulose and Congo Red molecules would block the hydrolysis by cellulase for all the fibers examined. It was also assumed that there would be a region that could be accessible to cellulase but not entirely to Congo Red. © 1993 John Wiley & Sons, Inc.     

The effect of pretreatment on the enzymic hydrolysis of cellulosic industrial waste

The enzymic hydrolysis of cellulosic waste material from industrial origins using commercial Tricoderma viride cellulase gave yields approaching 80% conversion following pretreatments. The yield was a function of the purity of the substrate and the pretreatments imposed. These included sterilisation, heating, ball-milling and alkali treatment. Highest yields of glucose or enzyme hydrolysis were achieved with a 4% solka floc suspension following pretreatment in 5% alkali, when the enzyme mix was 0.22IU cm^?3 of filter paper activity, 0.07IU cm^?3C_x enzyme activity and 0.14IU cm^?3 of β-glucosidase activity. Kraft pulp also gave up to 75% yields by this method.     

Photodegradation of the textile dye Reactive Black 5 in the presence of semiconducting oxides

The photocatalytic degradation of Reactive Black 5, a textile azo dye, has been investigated in aqueous heterogeneous solutions containing semiconductor oxides as photocatalysts. The disappearance of the organic molecule follows approximately a pseudo‐first kinetic order according to the Langmuir–Hinshelwood model. CO ₂, NO₃⁻, and SO₄ ²⁻ ions have been identified as mineralization products. Various commercial photocatalysts were compared with respect to their decolorization efficiency, as well as the production of CO₂. The effect of pH and H₂O₂ on the reaction rate was ascertained. © 1999 Society of Chemical Industry     

Studies in the utilization of agricultural waste products as filler in natural rubber compounds

Natural rubber samples were filled with agricultural waste products (cocoa pod husks and rubber‐seed shell) at 50 phr, mixed on a two‐roll mill, and cured using the semiefficient vulcanization system. The physicomechanical properties, tensile strength, modulus at 100% elongation, elongation at break, hardness, abrasion resistance, flex fatigue and compression set, of the agricultural waste products‐filled natural rubber compounds were determined and compared with the values obtained for vulcanisates filled with commercial carbon black (HAF N330). The effect of blending the raw and carbonized agricultural waste products with the commercial grade N330 carbon black on the physicomechanical properties of the natural compounds was studied. It was found that the raw agricultural waste products were ineffective compared with N330 carbon black as reinforcing filler for natural rubber compound mixes and could be classified as semireinforcing fillers. Blends containing up to 40 wt % of the raw agricultural waste products and more than 60 wt % of the carbonized waste products gave natural rubber compounds with comparable physciomechanical properties with compound obtained with N330 carbon black. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2561–2564, 2006     

基于酸改性的半焦对染料废水的吸附性能研究

为制备高效吸附材料,采用化学活化法对延安子长煤低温热解的半焦进行改性,并进行X射线衍射(XRD)、N2等温吸附、扫描电子显微镜(SEM)表征。以罗丹明B、酸性品红为目标物,采用吸附剂添加量、溶液p H、吸附时间等为考察参数,研究了酸改性半焦对罗丹明B、酸性品红模拟染料废水的吸附性能,探索了酸改性半焦对罗丹明B、酸性品红的吸附动力学行为。结果表明:改性半焦对2种染料有良好的吸附性能,准二级动力学模型的相关系数在0.999以上,模型饱和吸附量与实验值相近,很好地描述了2种染料在酸改性半焦上的吸附行为。     

Transesterification of waste cooking palm oil by MnZr with supported alumina as a potential heterogeneous catalyst

The transesterification of waste cooking palm oil (WCPO) with methanol into fatty acid methyl esters (FAMEs) was investigated using solid acidic mixed oxide catalysts Mn_3.5xZr_0.5yAl_xO₃ prepared via coprecipitation. The effects of reaction temperature, time, molar methanol-to-oil ratio, and catalyst loading were investigated. The stability of the catalytic activity was examined via leaching and reusability tests through five consecutive batch runs. The catalyst achieved a FAME content of more than 93%, and the optimal reaction conditions are as follows: reaction temperature of 150 °C, reaction time of 5 h, molar methanol-to-WCPO ratio of 14:1, and catalyst loading of 2.5 wt.%.     

Novel modified cellulosic polymers as drilling fluid additives with improved properties

Novel modified cellulosic polymers with amphoteric character were prepared by grafting 2-dimethylaminoethyl methacrylate (DM) and 4-vinylbenzene sulphonic acid sodium salt (VB) onto sodium carboxymethylcellulose (NaCMC), and characterized by IR and composition analyses. Their properties as drilling-fluid additives in oilfields were investigated with respect to shale inhibition, filtration control and viscosity enhancement. It is found that the grafting of DM enhances the shale-inhibition effectiveness and that the grafting of VB increases the tolerances to salt and temperature. Different from commonly used anionic and cationic polymeric additives, the modified cellulosic polymer with suitable structural parameters has both good shale-inhibition and mud properties. © 1999 Society of Chemical Industry     

Composites produced from waste plastic with agricultural and energy sector by-products

A three-stage route to chemically upcycle post-consumer poly(ethylene terephthalate) (PET) to produce high compressive strength composites is reported. This procedure involves initial glycolysis with diethylene glycol to produce a mixture (GPET) comprising oligomers of 2–7 terephthalate units followed by trans/esterification of GPET with fatty acid chains supplied by brown grease, an agricultural by-product of animal fat of relatively low nutritional or fuel value. This process yields PGB comprising a mixture of mono-terephthalate ester derivatives. The olefin units provided by unsaturated fatty acid chains in brown grease were crosslinked by an inverse vulcanization reaction with elemental sulfur to give composites GBS_x (x = wt% S, varied from 80%–90%). The compressive strengths of GBS₈₀ (27.5 ± 2.6 MPa) and GBS₉₀ (19.2 ± 0.8 MPa) exceed the compressive strength required of ordinary Portland cement (17 MPa) for its use in residential building foundations. The current route represents a way to repurpose waste plastic, energy sector by-product sulfur, and agricultural by-product brown grease to give high strength composites with mechanical properties suggesting their possible use to replace less sustainably sourced legacy structural materials.     

Synthesis,characterizations, and physical properties of carbon nanotubes coated by conducting polypyrrole

A new type of carbon nanotube (CNT) (diameter of <100 nm) coated by conducting polypyrrole (PPY) was synthesized by in situ polymerization on CNTs. The structure of the resulting complex nanotubes (CNT‐PPY) was characterized by elemental analysis, X‐ray photoelectron spectroscopy, Raman spectra, and X‐ray diffraction. These indicated no significant chemical interaction between PPY and the CNT. The electrical, magnetic, and thermal properties of the complex nanotubes were measured and showed the physical properties of the CNTs were modified by conducting PPY. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2605–2610, 1999