In this study, three different acrylonitrile (AN)-based polymers, including polyacrylonitrile (PAN), poly(acrylonitrile-covinyl acetate) [P(AN-co-VAc)], and poly(acrylonitrile-co-itaconic acid) [P(AN-co-IA)], were used as precursors to synthesize activated carbon nanofibers (ACNFs). An electrospinning method was used to produce nanofibers. Oxidative stabilization, carbonization, and finally, activation through a specific heating regimen were applied to the electrospun fibers to produce ACNFs. Stabilization, carbonization, and activation were carried out at 230, 600, and 750 8C, respectively. Scanning electron microscopy, thermogravimetric analysis (TGA), and porosimetry were used to characterize the fibers in each step. According to the fiber diameter variation measurements, the pore extension procedure overcame the shrinkage of the fibers with copolymer precursors. However, the shrinkage process dominated the scene for the PAN homopolymer, and this led to an increase in the fiber diameter. The 328 m 2 /g Brunauer-Emmett-Teller surface area for ACNFs with PAN precursor were augmented to 614 and 564 m 2 /g for P(AN-co-VAc) and P(AN-co-IA), respectively.The TGA results show that the P(AN-co-IA)-based ACNFs exhibited a higher thermal durability in comparison to the fibers of PAN and P(AN-co-VAc). The application of these copolymers instead of AN homopolymer enhanced the thermal stability and increased the surface area of the ACNFs even in low-temperature carbonization and activation processes. V C 2016 Wiley Periodicals, Inc. J. Appl.Polym. Sci. 2016, 133, 44381.

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Some of the authors of this publication are also working on these related projects: Enhancement of transport phenomena View projectDeveloping novel SCR catalysts for utilization in the reduction of the emissions such as mercury from coal-fired power plants. View Abstract In the present experimental study, the effects of electrical conductivity on electrospraying procedure are investigated. A metallic nozzle with 600 m ID as high voltage electrode and a stainless steel ring as a ground electrode were employed. Experiments were carried out in still room temperature. Four different aqueous KCl solutions were sprayed in various high voltages and flow rates. Results confirm that spraying modes changes with conductivity variation. For forming a cone shape, emerging from the nozzle, required applied electric field decreases with conductivity increasing. Results also revealed that conductivity of dispersed solution acts a main role on forming and elongation of the cones in electrospraying procedure. The size and velocity of emanated droplets are also investigated in order to gaining some insight to the electrospraying phenomenon. IntroductionElectrospraying of liquids is a well-established process for producing submicron particles. This spraying method (also known as electro hydrodynamic atomization) is a process in which high electric field is employed to disperse a liquid. High voltage is applied to a liquid supplied through an emitter (usually a metallic capillary). In electrospraying, the shear stress caused by the electric force applied to the surface of liquid, elongates the liquid meniscus formed at the tip of a capillary, to the form of a cone and/or a jet which then deforms and disrupts into droplets due to interplay of electrical and mechanical forces. In this method no additional purely mechanical energy is applied to spray the liquid. Electrohydrodynamic spraying (EHD spraying) has wide range of applications including fine resolution electrohydrodynamic printing [20,3], biomedical application especially drug delivery system [29,23], powder production [9, 11] and producing stable emulsions [13,16,21].Early works on the electrified surfaces has been done by Zeleny in 1917[24]. In 1969, Taylor conducted some experiments in electrified jets [22]. Cloupeau and Prunet-Foch introduced cone jet as one the modes which expects to have monodisperse produced droplets in 1989 [5]. Fernandez de la Mora and his coworkers investigated the droplets diameter and the current emitted from electrosprays in the well-known cone jet mode [8]. They also studied the effect of physical parameters like electrical conductivity, viscosity, liquid density and the feed rate on the electrospraying in cone jet mode [12]. Experimental observation of the dielectric constant effect on the cone jet mode spraying has also been investigated by D. R. Chen et al [4]. They proposed some scaling laws between produced droplets and dielectric constants.For other values of electric field and feed rates, some other regimes, different from cone jet mode...