Cu (II) removal using electrospun dual-responsive polyethersulfone-poly (dimethyl amino) ethyl methacrylate...

A novel electrospun dual-responsive polyethersulfone-poly(dimethyl amino) ethyl methacrylate nanofibrous adsorbent was fabricated via electrospinning for the removal of Cu (II) from aqueous solution. Morphological, chemical, and dual-responsiveness of the composite nanofibrous adsorbent were characterized using scanning electron microscope equipped with energy dispersive x-ray, Fourier transform infrared, and UV-VIS spectrophotometer, respectively. The obtained uniform and bead-free nanofibers were then used for the removal of Cu (II) from aqueous solution. Results showed that the temperature-responsiveness of the nanofibers is dependent on the pH of the solution, as indicated by the decreasing lower critical solution temperature with increasing pH level. Temperature and pH offer a synergistic effect on the adsorption of Cu (II), with maximum adsorption observed at pH 6.5 at 55 °C. Kinetic, thermodynamic, and isotherm studies indicate that the adsorption of copper ions follows chemisorption and is thermodynamically favored at increasing temperature. From the Langmuir isotherm model, the obtained maximum adsorption capacity, q_m, was 161.30 mg g^-1 at 55 °C. From the desorption studies, results showed that the maximum desorption was observed at pH 3 at 25 °C. In conclusion, PES-PDMAEMA has the capability to adsorb and desorb Cu (II) by adjusting both pH and temperature, hence it can be considered as an efficient and economical adsorbent for heavy metals such Cu (II).