Concentration of pectin solution : Forward osmosis performance and fouling analysis
[ 1 ] Instytut Technologii i Inżynierii Chemicznej, Wydział Technologii Chemicznej, Politechnika Poznańska | [ 2 ] Instytut Technologii Mechanicznej, Wydział Inżynierii Mechanicznej, Politechnika Poznańska | [ P ] employee | [ D ] phd student
2022
scientific article
english
- forward osmosis
- pectin
- fouling
- surface free energy
- digital holographic microscopy
EN The paper presents research on the possibility of using the forward osmosis (FO) technique to concentrate an aqueous pectin solution. Based on the preliminary studies on the effect of the concentration of the draw solution (DS) on the efficiency of concentration by the FO, a 3 M sodium chloride solution was selected as the DS for further processes. It was found that during the pectin concentration process, a continuous and compact fouling layer of gelled pectin was deposited on the membrane surface, which resulted in a significant decrease in the water flux. The flux decline was over ten times greater in the pectin concentration process than in the corresponding baseline process at water recovery equal to 80%. However, it should be emphasised that the gelled pectin layer was easily removable from the membrane surface. In order to analyse the fouling phenomenon during the pectin concentration process, comprehensive tests of the FO membrane surface with the deposited fouling layer and the membrane after removing the pectin gelled layer were carried out. The scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) as well as a non-destructive imaging method, i.e. digital holographic transmission microscopy (DHM), were applied. In addition, wettability tests were carried out with the use of polar and non-polar liquid and then, based on the measured values of the contact angle (sessile drop method), the value of the surface free energy (SFE), as well as the polar and non-polar interaction components were estimated according to the OWRK approach. It was found that despite significant changes in the membrane morphology, SFE values, roughness and texture, the tested FO membrane (after prior cleaning) may be used for multiple pectin concentration. The obtained flux recovery after 5 repeated consecutive pectin solution concentration processes and cleaning procedure was higher than 99%.
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