High Bovine Serum Albumin Rejection Research Articles

Photocatalytic antifouling PVDF ultrafiltration membranes based on synergy of graphene oxide and TiO2 for water treatment

A novel graphene oxide/TiO2-polyvinylidene fluoride (GO/TiO2-PVDF) hybrid ultrafiltration membrane has been successfully developed via the phase inversion technique by supplementing with GO/TiO2 nanocomposites, in which the synergistic coupling of GO and TiO2 could result in improved photocatalytic activity and endow hybrid membranes with photocatalytic antifouling function. Compared with PVDF membranes supplemented with TiO2 and GO, respectively, the GO/TiO2-PVDF membrane displayed significantly improved photodegradation efficiency (improved about 50–70%) and superior photodegradation kinetics (1.0–1.5 times faster) toward bovine serum albumin (BSA). Moreover, flux performance and flux recovery ratio of membranes revealed that the GO/TiO2-PVDF membrane could recover high flux after fouling, which thus presented self-cleaning property under UV static irradiation. Besides, the GO/TiO2-PVDF membrane showed a water flux up to 487.8Lm−2h−1, more than 2 times that of the pristine PVDF membrane, while keeping high BSA rejection (92.5%). Therefore, the GO/TiO2-PVDF membrane would have good potential in water treatment due to its high-performance multifunctional characters, i.e. separation, photocatalytic oxidation and self-cleaning, etc.

EFFECTS of pH ON the ULTRAFILTRATION of BOVINE SERUM ALBUMIN AT HIGH IONIC STRENGTH USING A MACROPOROUS TITANIA MEMBRANE

The ultrafiltration of bovine serum albumin (BSA) buffered at pH 3.8, 4.8 and 6.8 in solutions with ionic strengths greater than 0.05 mol dm−3 was investigated at pressures of 0.20 and 0.70 MPa using a macroporous titania membrane. Protein rejections as high as 0.94 were obtained. Both pH and pressure affected the permeability and rejection. the relative amount of irreversible fouling was estimated by evaluating parameters of a resistance model. Conditions providing the lowest fouling index and the least irreversible fouling while retaining high BSA rejection were obtained at the highest pH, 6.8, and lowest pressure, 0.20 MPa.

Preparations and properties of sodium alginate formed-in-place membranes

Sodium alginate formed-in-place membranes were formed on a macroporous titanium dioxide membrane substrate at pH 3.3, 6.5, and 10.5. To investigate the rate and the mechanism of the membrane formation, the dependence of the pressure-to-flux ratio, P/J, on time, t, during the formation was evaluated using diagnostic graphs ; (P/J) 2 , (P/J) 1/2 and -ln(P/J) vs. t. The microfiltration properties of the membranes were investigated by determining the permeability, J/P, and the rejection of a protein, bovine serum albumin (BSA), in 1 g/L solutions as a function of the concentration of added KCl. The stability of the membranes was evaluated by comparing the ratio of the resistances of the membranes at the end of the formation, R, after crossflow rinsing, R m , and after crossflow rinsing following the BSA microfiltration experiment, R α . The linearity of the graphs of (P/J) 2 vs. t of the membranes formed in neutral or basic conditions indicated that the membranes were formed by deposition of a layer, or cake, of the polyelectrolyte on the substrate, while the membrane formed at lower pH was initially deposited as a layer followed by a more complex mechanism. Only the membranes formed pH 3.3 were stable to the crossflow water rinse and retained high BSA rejection at high ionic strength. Their permeabilities were about 50% lower than the permeabilities obtained with the membranes formed at higher pH. The BSA rejection results imply that a continuous sodium alginate membrane is present for the membranes formed at pH 3.3 and that membranes retaining a macroporous structure are present for the membranes formed at pH 6.5 and 10.5.