Adsorption of anionic acid red G dye on polyaniline nanofibers synthesized by FeCl3 oxidant: Unravelling the role of synthetic conditions

Abstract

Polyaniline (PANI) has been considered as a high-efficient adsorbent for the dye removal from wastewater. Different synthetic conditions could offer PANI with comparable adsorption performance and yield, which are crucial for its large-scale application. Herein, the adsorption performance of PANIs, which synthesized by one-step polymerization method under different temperature and amount of FeCl3, for the removal of a typical anionic dye, Acid Red G (ARG), were investigated. As-synthesized PANIs were characterized by scanning electron microscopy, FT-IR spectroscopy, nitrogen adsorption-desorption isotherms and X-ray diffraction. Adsorption isotherms study result showed that low temperature was beneficial for the formation of highly crystallized PANI nanofibers with high adsorption performance, and high amount of FeCl3 could increase the yield of PANI. An optimal synthetic condition, where temperature is 20 °C and molar of aniline to FeCl3 is 1:4, was determined for PANI when using FeCl3 oxidant (PANIopt). The adsorption including kinetics, isotherms, and regeneration of PANIopt on ARG was then systemically investigated. The maximum adsorption capacity of PANIopt for ARG was found to be 491.20 mg g−1 at 35 °C. Moreover, adsorption mechanism study suggested that the efficient adsorption performance was related with the highly crystalized polymer chain of PANI, which provides abundant active sites for the adsorption of ARG via electrostatic interaction.