MANNAN PRECIPITATION FROM ALOE VERA LEAF PULP JUICE USING METHANOL AND ISOPROPYL ALCOHOL AS ANTI-SOLVENT: EXPERIMENTAL AND EMPIRICAL MODELLING APPROACH

Abstract

Precipitation of mannan from Aloe vera leaf pulp juice was investigated using anti-solvent precipitation process under room temperature condition. The aims of this work were to study the effects of types (methanol and isopropyl alcohol) and amount of anti-solvent on the precipitation phenomena and to propose a simple mathematics model for evaluating the precipitation rate of mannan (Rβ). The experiments were carried out using a semi batch system; where continuous drop wise addition of anti-solvent to the Aloe vera leaf pulp juice was kept constant at 50.4 mL/min, while the speed of stirring was maintained at 675 rpm. At every run of the experiments, the time at which the precipitation began was recorded and the experiment was terminated when no further precipitation occurred. The samples were withdrawn from the system at every 25 min after the first precipitation for mannan analysis. The results of this work showed that isopropyl alcohol acted as a more effective antisolvent to precipitate mannan from Aloe vera leaf pulp juice than methanol. The mathematics model represented the precipitation phenomena fairly well with average relative deviation only 11.73%, and finally suggested that the precipitation rate obeyed the zero order.