Kinetic studies on the adsorption of dark colored compoundsfrom apple juice using LSA—800B adsorbent resin

The kinetic process of adsorption and decolorrization for apple juice by using LSA-800B adsorbent resin were studied at different concentrations (1,2,4,8 g adsorbent resin per liter of apple juice) and temperature (25～70℃).The results showed that the adsorption data of LSA—800B adsorbent resin fitted well with both Langmuir and Freundlich models. The parameters of the models (K_ad、Q₀、K_f and n) were also obtained at different temperatures. The changes of adsorption enthalpy value (ΔH) of 4.16 kJ/mol indicated the endothermic nature of the adsorption process. A decrease of Gibbs free energy (ΔG) with temperature increase also indicated the spontaneous nature of the process. The kinetic parameters of the adsorption and decolorrization for apple juice at different temperatures using adsorbent resin of different concentrations were also determined The adsorption ability was improved with increasing temperature, but the initial equilibrium time was decreased. The adsorption effect was comparatively evident at 2～4 g/L resin concentration, also the cover rate (θ_e) reached to initial equilibrium was higher at 55℃. Hereby, the suitable temperature and concentration for the adsorption and decolorrization of apple juice by using the resin can be defined as 55℃ and 2～4 g/L.