China
Africa
Explore chapters and articles related to this topic
Polymers in Special Uses
Published in Manas Chanda, Plastics Technology Handbook, 2017
The production of PPy in a nanofiber form has been traditionally accomplished through templated synthesis methods which employ mesoporous silica, anodized aluminum oxide membrane, and particle track-etched membranes [41–43], while a bulk growth approach using V2O5 seed as a template has been reported more recently [44]. However, nanofibers produced by these methods are typically very short and not easy to handle for device fabrication. An electrospinning technique has thus been widely used for producing polymeric nanofibers in a nonwoven mat that is amenable to handling macroscopically [45]. (Note: Electrospinning is a process that produces continuous polymer fibers through the action of an external electric field imposd on a polymer solution. For a review of the process see previous publications [45–47].) Nanofibers can also be deposited directly on device substrates. Polyaniline being soluble, the electrospinning process has been successfully utilized for the production of polyaniline nanofibers [48]. However, this process cannot be directly employed for producing PPy nanofiber due to the intractability of PPy.
Adsorptive removal of methyl orange with polyaniline nanofibers: an unconventional adsorbent for water treatment
Published in Environmental Technology, 2020
In this research work, polyaniline nanofibers were used as a novel adsorbent to remove the MO dye from its aqueous solution. Polyaniline nanofibers were synthesized by the interfacial polymerization method. Further, the synthesized adsorbent was characterized by SEM, HRTEM, XRD, ZETA potential, four-probe technique, BET and FTIR techniques. SEM results indicated the nano-range of the synthesized fibrous polyaniline which was further confirmed to be of 60 ± 5 nm in diameter by HRTEM. BET analysis reported the enhanced (approx. 4 times) surface area of PANI nanofibers (48.83 m2 g−1) as compared with conventional polyaniline (13.65 m2 g−1). This enhanced surface area aided in more adsorption of the MO dye on this nanostructured form of polyaniline. UV–visible spectroscopy was used to analyse the un-adsorbed amount of the dye. Batch adsorption experiments were used to study the kinetics of the adsorption system. Kinetics of the adsorption of the dye was studied using different kinetic models such as pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion models. It has been observed that pseudo-second-order model was best fitted to the adsorption data of MO which indicated the involvement of chemisorption in the removal of the MO dye by polyaniline nanofibers. It has been seen that intra-particle diffusion is also playing a significant role in the adsorption along with chemisorption as the value of the regression coefficient obtained for the best-fitted straight line for the intra-particle diffusion model is significantly high, i.e. R2 = 0.858. In addition, Langmuir, Freundlich and Temkin isotherm models were also used to analyse the equilibrium data. The best fitting of the data was observed with the Freundlich model. So, it can be concluded that the adsorptive removal of the MO dye occurred on the heterogeneous surface of the polyaniline and there is a formation of multilayer during this adsorption experiment. The effects of different parameters such as contact time, initial dye concentration and pH were also studied and the equilibrium values of these parameters are found to be 80 min, 7 mg L−1 and pH∼7, respectively. From this study, it is evident that polyaniline nanofibers can be used as an efficient adsorbent for the removal of acidic dyes from wastewater. The studies can further be scaled-up on the pilot and commercial scale for the combating of water pollution by cause of the presence of harmful dyes. This needs more experimentation to check the suitability of polyaniline nanofibers as an adsorbent for other dyes present in the effluent.