The effect of ultrafiltration transmembrane permeation on the flow field in a surrogate system of an artificial kidney

Abstract

Renal Replacement Therapies generally associated to the Artificial Kidney (AK) are membrane-based treatments that assure the separation functions of the failing kidney in extracorporeal blood circulation. Their progress from conventional hemodialysis towards high-flux hemodialysis (HFHD) through the introduction of ultrafiltration membranes characterized by high convective permeation fluxes intensified the need of elucidating the effect of the membrane fluid removal rates on the increase of the potentially blood-traumatizing shear stresses developed adjacently to the membrane. The AK surrogate consisting of two-compartments separated by an ultrafiltration membrane is set to have water circulation in the upper chamber mimicking the blood flow rates and the membrane fluid removal rates typical of HFHD. Pressure drop mirrors the shear stresses quantification and the modification of the velocities profiles. The increase on pressure drop when comparing flows in slits with a permeable membrane and an impermeable wall is ca. 512% and 576% for $ \mathrm{CA}22/5\%{\mathrm{SiO}}_2 $ and $ \mathrm{CA}30/5\%{\mathrm{SiO}}_2 $ membranes, respectively.

A Novel Strategy for Enhanced Sequestration of Protein-Bound Uremic Toxins Using Smart Hybrid Membranes

“…In terms of permeation performance, the CA/SiO 2 membranes were classified as suitable for high-flux hemodialysis, fully permeated urea, creatinine, uric acid (surrogate markers of low molecular weight water-soluble compounds (LMWMs)), and p -cresyl sulfate (a surrogate marker of PBUTs) while completely rejecting albumin (a vital component of the blood which cannot be removed by hemodialysis membranes) [ 21 ]. Andrade et al [ 22 ] developed another group of MHMs, CA/SiO 2 /SiO 1.5 -(CH 2 ) 3 NH 2 , using two silicon precursors: TEOS (up to 5 mol%) and (3-aminopropyl)-triethoxysilane (APTES) (up to 50 mol%).…”

Improving Structural Homogeneity, Hydraulic Permeability, and Mechanical Performance of Asymmetric Monophasic Cellulose Acetate/Silica Membranes: Spinodal Decomposition Mix

“…Gonçalves and Faria pioneered an innovative strategy to fabricate monophasic hybrid CA/SiO 2 -based membranes [ 7 , 8 , 9 , 10 , 11 , 12 ] by combining the membranes’ phase inversion technique [ 13 ] with sol–gel methodology [ 14 , 15 ]. In this approach, in situ homo- and hetero-condensation reactions take place during casting solution homogenization (under acid catalysis) between silanols (≡Si–OH−) from the hydrolyzed silica precursors and silanols and hydroxyls (OH−) from the CA polymer, respectively.…”

Novel Cellulose Acetate-Based Monophasic Hybrid Membranes for Improved Blood Purification Devices: Characterization under Dynamic Conditions

“…Nevertheless, CA membranes exhibit some drawbacks-namely, limited chemical resistance, low mechanical strength, low shelf life, and small pore size [23]. To overcome these limitations, our research group has focused on the development of novel monophasic hybrid CA-based membranes, which combine the high mechanical and thermal stability of the inorganic material with the flexibility, ductility, and processability of CA [24][25][26][27][28]. In a recent study [27], a modified version of the phase inversion technique [13] coupled with the sol-gel method [29,30] was used to synthesize novel monophasic hybrid skinned amine-functionalized CA-SiO 2 -(CH 2 ) 3 NH 2 membranes.…”