Quang Trong Nguyen

Biospecific ultrafiltration: A promising purification technique for proteins?

Abstract When a protein is exposed to a ligand linked to a water soluble polymer, a macrocomplex can be formed that can be isolated from the contaminant medium by different methods such as affinity partitioning or gel filtration. Ultrafiltration technique has also been tested in the separation of trypsin and chymotrypsin using a high molecular weight dextran— p -aminobenzamidine as a macroligand. Some theoretical considerations are given in order to evaluate the performance that can be expected from this biospecific complexation—ultrafiltration technique in the separation of biological species.

Dye and bacteria photodegradations with anatase-loaded microporous poly(vinylidene fluoride) membranes

Non-skinned microporous membranes containing anatase particles were fabricated without anatase loss with the dry cast technique. The membranes were characterized by scanning electron microscopy, X-ray diffraction (XRD), infrared spectroscopy, thermal gravimetry analysis and contact angle measurements. Anatase particles were fairly well distributed in the crystallized-PVDF microporous matrix, mainly as aggregates. The membrane porosity, as well as their nitrogen and water permeabilities, reached a maximum at 0.5 TiO2/PVDF weight ratio. The anatase-loaded PVDF membranes were successfully used in the dye and bacteria photodegradations catalyzed by anatase particles. The dye sorption and the photodegradation kinetics with the membrane of 0.5 TiO2/PVDF weight ratio obeyed the Freundlich and the first-order laws, respectively. In the photodegradation of a dye mixture, the better sorbed dye was preferentially photodegraded, suggesting the key role of dye sorption in the photodegradation mechanism. The technical feasibility of the supported photocatalyst in a continuous discoloration of a dye solution was shown in runs of a flat-type reactor under a black-light lamp or direct solar light.

Study of Polysulfone and Polyacrylic Acid (PSF/PAA) Membranes Morphology by Kinetic Method and Scanning Electronic Microscopy

This work focuses on the study of the morphology forming of Polysulfone (PSf) and polyacrylic acid (PAA) membranes which are prepared by mixing both of the polymers in DMF and the obtained blend is precipitated in water (non-solvent). The precipitation kinetic and the effects of polysulfone concentration, drying-time in free-air and proportions of both polymers are investigated. nBased on the SEM technique, the kinetic and viscosity measurements, and the visual observations, this study brings to the fore the different steps of the morphology forming of PSf/PAA membranes: formation of finger-like structures, sponge-like-structures, inner pores, superficial pores and the craters. Appearance of these structures is governed by the exchange process, between casting polymer-solution and the precipitation-bath (coagulation), which is controlled by operating conditions. This work constitutes a great tool in understanding the mechanisms of the morphology forming of PSf/PAA membranes and to improve their performances: preparation of tailored membrane.