Design of novel graphene oxide/halloysite nanotube@polyaniline nanohybrid for the removal of diclofenac sodium from aqueous solution

Abstract

In recent years, pharmaceutical pollutants are regularly detected in wastewater. An urgent initiative for controlling and removal of pharmaceutical contaminants from water is needed. Herein, graphene oxide/halloysite nanotubes @polyaniline (GO/HNT@PANI) nanohybrid has been synthesized and employed as an adsorbent for the removal of diclofenac sodium (DS) from an aqueous solution. The experimental parameters, including variation in pH, contact time, concentration, and temperature were optimized for the removal of DS. The prepared materials were characterized using SEM, HR-TEM, EDX, XRD, BET, and FTIR techniques. The highest decontamination of DS (633.680 mg g−1) was achieved within 60 min at pH 3.0 The kinetic data were best fitted to the pseudo-first-order kinetics. The adsorption equilibrium data were fitted to non-linear Langmuir, Freundlich, and Temkin models and the results revealed that the Langmuir model is the best-fitted isotherm. The thermodynamic study exhibited a spontaneous endothermic adsorption process. The nanohybrid exhibited highly improved adsorptive uptake contrasting to the other reported adsorbents. The adsorption of DS occurred through hydrogen bonding, π–π electron donor-acceptor, and electrostatic interactions. Moreover, the nanohybrid demonstrated its regenerative capability up to five times without any significant loss by simple washing with 0.1 mol L−1(aq) ethanol. The results revealed that GO/HNT@PANI nanohybrid is a highly efficient material for the removal of emerging pharmaceutical pollutants in water.