Removal of free fatty acid from waste cooking oil using an adsorbent derived from cassava peels

The present study investigated the potential use of the cassava peel-derived adsorbent for removal of free fatty acid (FFA) from waste cooking oil (WCO). The adsorbent A3 was developed by calcination at 200 °C for 2 hours, followed by NaOH modification. The surface morphology and functional groups of A3 were characterized using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Adsorption parameters, such as adsorbent dose, contact time, and temperature, influenced the adsorption efficiency of A3 for FFA. Isotherms, kinetics and thermodynamics of free fatty acid (FFA) adsorption onto A3 were investigated. The maximum adsorption capacity (qm) of A3 for FFA was 322.58 mg/g at a temperature of 35 °C. Adsorption isotherm was well described by the Freundlich model (R2=0.9676), while adsorption kinetics was best fitted with pseudo-second order model (R2=0.9996). Kinetic data revealed that the adsorption of FFA onto A3 was chemisorption. Thermodynamic studies revealed that FFA adsorption was endothermic, favorable, and spontaneous. In addition, diethyl ether and chloroform : methanol (2 : 1, v/v) could be used for chemical regeneration of A3. Our results confirmed that A3 has the potential to be a suitable adsorbent for FFA removal from WCO.