Properties of microfiltration membranes: Mechanisms of flux loss in the recovery of an enzyme

Abstract

The transmission and rate of filtration of the enzyme yeast alcohol dehydrogenase (YADH) has been studied at capillary pore microfiltration membranes. Photon correlation spectroscopy (PCS) with nanometer resolution showed that the enzyme existed as discreate molecules only for a narrow range of pH and ionic strength. Under such conditions, the transmission of the enzyme was high. However, the rate of filtration still decreased continuously with time. Analyssis of the time dependence of the rate of filtration indicated that this decrease was due to in-pore enzyme deposition at low concentration ("standard blocking model") and suface depositon at high concentration ("cake filtration model"). Use of atomic force microscopy (AFM) gave unequivocal and quantitative confirmation of these inferences. The work shows the great advantage of using advanced physical characterization techniques, both for the identification of the optimum conditions for filtration (PCS) and for the elucidation of mechanisms giving rise to inefficiencies in the filtration process (AFM). (c) 1995 John Wiley & Sons, Inc.

Atomic Force Microscope Studies of Membranes: Surface Pore Structures of Diaflo Ultrafiltration Membranes

“…The AFM software allows quantitative determination of the diameter of pores by the use of the images in conjunction -YM3, YM10, YM30, and YM100, with MWCO of with digitally stored line profiles (16). Pore size distribu-3000, 10,000, 30,000, and 100,000, respectively, made from tions obtained by analyzing large numbers of pores in this regenerated cellulose, way are shown in Fig.…”

“…AFM has also been used to elucidate the mechaprocess separating materials in the size range 0.1 mm-5 nm. nisms giving rise to inefficiencies (fouling) in membrane The effectiveness of ultrafiltration as a separation process processing (16). However, with one exception (14), memwill clearly depend on the pore size distribution of the mem-branes have been studied in ''contact mode.''…”

Properties of protein adsorption onto pore surface during microfiltration: Effects of solution environment and membrane hydrophobicity

“…the external fouling. Many researchers have indirectly distinguished the location of fouling in terms of flux decline with the blocking filtration models [1,3,4,[25][26][27] while the flux decline reflects the overall blockage of the membrane. The static adsorption method, which means the adsorption by immersing a piece of membrane into protein solution, is also generally employed to characterize the effect of protein adsorption on the filtration performance of MF or UF membranes [6,11,15,17,20,23,28,29] while the adsorption isotherm during filtration can be affected by convective flow in pore [2].…”

Comparison and efficiency of two membranes (modified MF and UF) during enzymatic hydrolysis of haemoglobin in a membrane bioreactor

“…The cake formation model (CFM), t/V p = K CFM V p /2 + 1/Q p ; the loss of the rate of filtration is due to the surface deposition of enzyme and protein at high concentration. K SBM and K CFM are constant, Q p is the initial permeate flow rate of filtration, t the time and V p is the volume of permeate filtered [12,13].…”

“…They are highly selective, and have long life span. Nevertheless, there are some limitations to the use of these membranes due mainly to the high investment necessary to obtain membrane plants [12][13][14][15][16][17][18][19][20][21].…”