Morphology and water flux of produced cellulose acetate membranes reinforced by the design of experiments (DOE).

Cellulose acetate (CA) ultrafiltration membranes were successfully prepared using the non-solvent induced phase separation (NIPS) methodology. This technique is used to produce porous membranes for a large variety of applications. However, the formation of a dense skin during the process reduces membrane pure water flux (PWF). To overcome this issue, three parameters were investigated: CA/NMP (N-methyl-2-pyrrolidone) ratio in the casting solution, acetone (Ac)/water (W) ratio in the precipitation bath composition (PBC) and support material (glass/polyethylene). The effect of each factor on the mean pore size, water contact angle, porosity and PWF was supported by Taguchi design. The increase in the CA/NMP ratio reduced mean pore size and porosity. In contrast, there was an increase in porosity and hydrophilicity with increasing Ac/W ratio. The maximum value of PWF was obtained for membranes prepared using a PE support. ANOVA showed that most, but not all, factors had significant effects on the parameters measured.

Porous composites based on cellulose acetate and alfa-hematite with optical and antimicrobial properties.

Polymer nanoparticles (NPs) composites are rapidly gaining attention due to their high potential for application in several technological fields. On one hand, polymers contribute to balance the attractive magnetic and van der Waals forces that act on NPs and thus reduce their agglomeration. On the other hand, NPs can bring into the composites their inherent properties as nanosized objects. In this work, hematite NPs were blended with cellulose acetate (CA) polymer and thin nanocomposite films were produced by the non-solvent induced phase separation technique. A full physicochemical characterization of these composite materials confirmed its superior character in terms of structure, thermal stability, electronic/optical and antibacterial properties when compared to the polymer on its own and opens the door to its further validation in adsorptive and photocatalytic applications.

Use of laccase together with redox mediators to decolourize Remazol Brilliant Blue R.

A pure fungal laccase, obtained from a commercial formulation used in the textile industry, did not decolourize Remazol Brilliant Blue R (RBBR). Decolourization was only observed when a small molecular weight redox mediator was added together with the laccase. Under the conditions specified, violuric acid (5.7 mM) was the most effective mediator studied and almost complete decolourization was observed within 20 min. In contrast, 1-hydroxybenzotriazole (HOBT, 11 mM) decolourized RBBR at about a two-fold slower rate and to a lesser extent. Also, higher concentrations of HOBT were inhibitory which could be due to inactivation of laccase by the toxic HOBT radical. The commercial laccase formulation that contained phenothiazine-10-propionic acid as the mediator was least effective, giving 30% decolourization under equivalent conditions. We suggest that similar laccase plus mediator systems could be used for the detoxification of related anthraquinone textile dyes.

Decolorization of an anthraquinone-type dye using a laccase formulation.

Decolorization of the dye Remazol Brilliant Blue R (RBBR) was studied, as it is representative of an important class of recalcitrant anthraquinone-type dyes. For this purpose a commercial laccase formulation (CLF) containing laccase, a redox mediator and a non-ionic surfactant was used. Small molecular weight components were removed from the CLF by gel filtration, which made it possible to compare the effect of its laccase alone. Apart from slightly better thermostability of the CLF as compared with the laccase alone, the pH and temperature profiles were similar regardless of the presence of the small molecular weight components. The laccase alone did not decolorize RBBR. A small molecular weight redox mediator (HBT) was necessary for decolorization to occur. A comparison of the kinetics of RBBR decolorization using the CLF and its laccase alone is reported. Provided that a redox mediator is included, it is suggested that laccase may be suitable for the wastewater treatment of similar anthraquinone dyes.