Concentration and crystallization of Microbial Xylitol from oil palm empty fruit bunch (OPEFB) using submerged direct contact membrane distillation (DCMD)

Abstract

Xylitol possess high solubility in water and increase viscosity at high temperature, making the concentration process become challenging. This study demonstrated the applicability of Membrane Distillation (MD) in concentrating xylitol solutions and evaluates its performance at different conditions and feed compositions. MD was capable of concentrating pure xylitol solution to reach the supersaturated condition. However, when Oil Palm Empty Fruit Bunch (OPEFB) hydrolysate fermentation broth was used, fouling was observed due to the presence of impurities, despite the application of feed agitation. The batch crystallization of xylitol were conducted at 5 °C with a seed addition of 0.5–0.8%-wt. Higher seed concentrations were required to induce crystallization in OPEFB hydrolysate due to lower xylitol concentrations and impurity presence. Furthermore, impurities influenced the quality of the crystals, resulting in crystal purities of 98.98% and 94.56% in the synthetic solution and OPEFB hydrolysate, respectively. These findings indicated notable impact of crystallization temperature, seed addition, and impurity on xylitol crystallization.