Study on commercial membranes and sweeping gas membrane distillation for concentrating of glucose syrup

Abstract

In this work, sweeping gas membrane distillation (SGMD) process was used for concentrating of glucose syrup. The main questions in this work include: is SGMD process practical for concentrating of glucose solution prior the fermentation step in bioethanol process?. and are the commercially available hydrophobic membranes sufficient enough to develop the SGMD process in pilot scale for this issue?. To answer these questions, SGMD process was performed using three commercial membranes made of PP, PVDF and PTFE. All membranes characterized using scanning electron and atomic force microscopes for their morphological and topographical features. Important operating parameters including feed temperature (45-65O C), feed flow rate (400-800 mL/min), feed concentration (10-50 g/L), and gas flow rate (0.113-0.453 N.m3 /h) were studied for their effects on the permeate flux and the optimized parameters were then reported. Moreover, the influence of three flow arrangements of SGMD module (co-current, counter-current and cross-current) on the permeate flux was studied. The best performance (the highest permeate flux and rejection) was achieved when the PTFE membrane (0.22 µm) was used under the optimum operating conditions (feed temperature: 65o C; feed flow rate: 600 mL/min; gas flow rate: 0.453 N.m3 /h; feed flow channel depth: 2 mm; and the cross-current flow arrangement). Results indicated that SGMD process is a promising option for concentrating of the sugar syrup prior the fermentation step in the bioethanol production process.