Fast Production of Activated Carbon from Pomegranate Peels by Combining Microwave Heating and Phosphoric Acid Activation for Paracetamol Adsorption

Abstract

Pomegranate peels, abundant raw precursor in Tunisia, were converted into activated carbon by means of microwave heating using phosphoric acid activation. The influence of the activation temperature and irradiation time on the process yield and porous texture of the resulting activated carbons was investigated. Textural properties were studied through the nitrogen adsorption-desorption isotherms and the scanning electron microscopy. The surface chemical properties were characterized by acid-base titration, point of zero charge, and Fourier-Transform Fourier transform infrared spectroscopy spectra. Paracetamol, a widely applied pharmaceutical, was selected to examine the adsorptive behavior of the activated carbon prepared in the optimum conditions. A series of experiments were conducted in a batch system to assess the influence of parameters, that is, pH, initial concentration, and adsorption temperature. The prepared activated carbons showed the high Brunauer-Emmett-Teller surface area (1,657 m2/g) and the important total pore volume (0.91 cm3/g) for an activation temperature and irradiation time of 450°C and 10 min, respectively. The adsorption performance illustrated an encouraging result. The Langmuir equilibrium adsorption capacity was 238 mg/g. Estimated thermodynamic parameters show a spontaneous and exothermic adsorption process. Microwave heating as a simple process provides a high-quality activated carbon in a short time. The obtaining results make microwave heating, combined with phosphoric acid, a feasible method for producing successful adsorbent for paracetamol removal.