Thermodynamics study of linamarin sorption during its isolation from cassava

Linamarin is an important biomaterial. The removal of linamarin from aqueous solutions at different contact times, temperatures and initial concentration of crude cassava extract during its isolation using activated carbon was investigated. The extent of linamarin removal increases with increase in initial concentration of extract, contact time and temperature of the solution. The adsorption isotherm is described by means of composite isotherm where U-shaped isotherm was observed. The mole of linamarin adsorbed per pore volume of activated carbon (n1s) at different temperatures (298, 303, 318, 328, and 338 K) was almost equal (0.99, 1.00, 1.01, 1.00 and 1.00 g mol/cm3). The activation energy of the system (Ea) was calculated as 22.61 kJ/mol. The free energy of the adsorption (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) changes were calculated to predict the nature of adsorption. The estimated values of ΔG° at 298, 303, 318, 328, and 338 K were −2.45, 1.69, 1.80, 1.70, and 1.73 kJ/mol, respectively, which are relatively high except at 298 K, indicating endothermic and non-spontaneous process.