Hydrodynamic performance of 3D printed turbulence promoters in cross-flow ultrafiltrations of Psidium myrtoides extract

Membrane separations for fruit juice processing have been largely investigated, but membrane fouling is still a limitation to be overcome. Here, the use of turbulence promoters to increase the permeate flux of purple araca fruit (Psidium myrtoides) extract through flat polymeric membranes was investigated. The turbulence promoters were produced using 3D printing technology with two different cylindrical pin diameters (2.5 and 3.5 cm). Results show that the ultrafiltration membrane was efficient to concentrate the bioactive compounds of purple araca fruit extract. Retentions of total polyphenol and flavonoid compounds were 95 % and 90 %, respectively. The use of turbulence promoters increased the permeate flux by up to 78 %. According to computational fluid dynamics (CFD), the turbulence promoters with diameters of 2.5 and 3.5 mm increased the flow velocity on the membrane surface in 38.4 % and 30.7 %, respectively, and increases in turbulence intensity were of 69.0 % and 43.2 %, respectively. In addition, the turbulence promoters with diameters of 2.5 and 3.5 mm increased the wall shear stress from 1.57 to 3.12 and 3.07 Pa, respectively. Thus, the turbulence promoters had positive effects on hydrodynamics during ultrafiltration of purple araca fruit extract.