Utilization and reusability of hydroxyethyl cellulose alumina based aerogels for the removal of spilled oil.

Nowadays millions of oil tons are spilled into the environment causing important damage. Therefore, the development of new technologies and materials are needed to remediate this problem. In this study, hydroxyethyl cellulose alumina-based aerogels are synthesized by an environmentally friendly freeze-drying process to be used as sorbents for oil spills. It is demonstrated that the oil retention coefficient depends on the viscosity of the oil and the amount of hydroxyethyl cellulose contained in the aerogel, being 10% the optimal proportion. The aerogel synthetized with this content of hydroxyethyl cellulose displays the most favourable physicochemical and morphological properties to retain different oil spills, achieving 5.5 times its weight in comparison to its dry state. In addition, reusability experiments washing the aerogel with acetone or ethanol after the oil retention are carried out. Results show an improvement after a long washing of the sorbent with acetone, resulting in an oil weight gain of 38.7%.

Immobilized laccase on polyimide aerogels for removal of carbamazepine.

Since it is known that conventional wastewater treatment plants cannot completely remove pharmaceutical compounds, such as carbamazepine, the need for their removal has intensified. The use of biocatalysts, such as enzyme is an environmentally friendly method for carbamazepine biodegradation. Nevertheless, enzyme immobilization is required to facilitate the recovery and reusability and avoid the loss of enzyme. In this work, laccase was immobilized on modified polyimide aerogels by means of covalent bonding. Results showed that the immobilized laccase on polyimide aerogels possesses significantly improved activity under acidic or basic pH range in comparison with the free enzyme. Furthermore, for all the temperature range the activity of the immobilized enzyme was higher compared to the free enzyme form. The storage stability improved by the immobilization on this support material. The reusability tests towards oxidation of 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) showed that the immobilized laccase maintained 22% of the initial activity after 7 cycles. Immobilized laccase on polyimide aerogels for carbamazepine (CBZ) degradation exhibited 76% and 74% removal in spiked water and secondary effluent, respectively. Furthermore, after 7 cycles the CBZ removal efficiency remained higher (50% and 65% for spiked water and secondary effluent, respectively).