Kazumi Satoh

FT-IR analysis of BSA fouled on ultrafiltration and microfiltration membranes

Abstract Protein fouling is a critical problem for ultrafiltration (UF) and microfiltration (MF). In the latest decade, a Fourier-transform infrared (FT-IR) spectroscopic method has been developed to quantify protein secondary structure by employing the amide I spectral region. The most attractive feature of FT-IR analysis is its ability to analyze proteins in various conditions. In this study, we employed FT-IR to quantify the conformational change of protein fouled on polysulfone (PS) UF membrane and polytetrafluoroethylene (PTFE) MF membrane. Bovine serum albumin (BSA) was adopted as a model protein. BSA adsorption onto the membranes was performed at 4°C and gel-like BSA deposits on the membranes were prepared by filtration at room temperature. FT-IR analysis revealed that the BSA adsorbed onto PS UF membrane had little change in the secondary structure, whereas the BSA adsorbed onto PTFE MF membrane had remarkable changes in the secondary structure, which were a decrease in α-helix content from 66 to 50% and an increase in β-sheet content from 21 to 36%. In addition, gel-like BSA deposits on both of the membranes had marked changes in secondary structure, which were similar to the changes in the BSA adsorbed onto the PTFE MF membrane. And the BSA concentration did not significantly affect the changes in the secondary structure of BSA fouled on both the UF and MF membranes.

Hydrogen recovery from cyclohexane as a chemical hydrogen carrier using a palladium membrane reactor

A palladium membrane reactor was applied to recover the hydrogen from cyclohexane as one of the promising chemical hydrogen carriers. The operation conditions of the palladium membrane reactor to obtain a higher hydrogen recovery were predicted by computer simulation. As a result, it was shown that the hydrogen recovery rate becomes higher as the pressure on the hydrogen permeation side is lowered below atmospheric pressure or as the reaction pressure increases. This was confirmed experimentally. As the perm-side pressure was lowered, the conversion as well as the hydrogen recovery rate at 573 K was found to increase. About 80% of the hydrogen contained in cyclohexane, depending on the operation condition was successfully recovered.

Microscopic observation of emulsion droplet formation from a polycarbonate membrane

Real-time microscopic observations of the membrane emulsification process were performed using a novel membrane module and a microscope video system. The droplet growth and detachment processes from the membrane pores were analyzed from visual images taken during the experimental runs. A hydrophilic polycarbonate membrane with a mean pore size of 10 μm was employed. Microscopic observations of the oil droplet formation process from the membrane verified the continuous phase flow-driven droplet formation. This paper also describes the influences of the continuous phase flow velocity and the surfactant type on membrane emulsification. The use of anionic and nonionic surfactants resulted in successful membrane emulsification with no droplet coalescence at flow velocities greater than 0.1 m s−1. The droplet size of the resulting oil-in-water (O/W) emulsions decreased with an increase in the flow velocity, remaining almost constant at flow velocities greater than 0.4 m s−1. The emulsions prepared under these conditions had the average droplet sizes of about 20 μm and the coefficients of variation of 20–50%. In contrast, a cationic surfactant-containing system resulted in no droplet formation due to complete wetting of the membrane surface with the dispersed phase. An analysis of the surfactant–polycarbonate membrane interaction and contact angle measurements explained well the results that the membrane emulsification behavior critically depended on the type of surfactant used.