Sunflower seed shells@polyaniline: a novel composite for the removal of pharmaceutical pollutants from wastewater

Abstract

The purpose of the present work is to prepare and characterise a low-cost composite based on sunflowers seed shell (SFS) coated with a small amount of polyaniline. This composite was used in the removal of pharmaceutical compounds from aqueous solutions (sodium salicylate SS). SFS@PANI composite was characterised by scanning electron microscopy, thermogravimetry and infrared spectroscopy. The removal of SS from wastewater, using the synthesised composite as an adsorbent material, was investigated as a function of adsorbent dose, initial concentration, pH of the solution, temperature and contact time. The equilibrium contact time was achieved at 60 min and the experimental results show that the kinetic model of pseudo-second-order (PSO) and Langmuir isotherm provided a good fitting of the whole experimental data. Thermodynamic parameters like free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were also calculated. The obtained results suggest that the adsorption process is spontaneous and exothermic in nature. Additionally, the prepared Sunflower seed shell@Polyaniline (SFS@PANI) composite exhibited a good regeneration capacity and excellent reusability after four cycles.