Functional Chitosan Derivative and Chitin as Decolorization Materials for Methylene Blue and Methyl Orange from Aqueous Solution

Dyes are classified as one of the major pollutants of water. They have negative impacts not only on environment but also on human health. In fact, wastewater that contains these harmful substances requires many types of treatments. Therefore, alternative methods and adsorption agents are needed. Herein, we propose to evaluate the decolorization of methylene blue (MB) and methyl orange (MO) as two models of soluble dyes from water using chitin and chitosan-graft-polyacrylamide. Furthermore, the applicability of these biomacromolecules as alternative adsorption agents, their sticking probability and desorption were also examined. Experimental parameters such as dye concentration, contact time, pH solution, adsorbent dosage and temperature were thoroughly examined for the grafted chitosan and chitin. The activation energy (Ea) and the thermodynamic variables (i. e., standard Gibb's free energy (D G0), standard enthalpy (D H0), and standard entropy (D S0)) were determined using the Van't Hoff and Arrhenius equations. The sticking probability (S*) model for MB and MO removal by chitin and the chitosan derivative demonstrated that both dyes were successfully removed under the proposed conditions. Desorption studies of MB and MO showed the reusability of both materials, suggesting their application for removing dyes from aqueous solution.The authors are grateful for the financial support of the Department of Education of the Basque Government (IT1008-16)

Eco-friendly isolation and characterization of nanochitin from different origins by microwave irradiation: optimization using response surface methodology

[EN] The extraction of nanochitin from marine waste has attracted great industrial interest due to its unique properties, namely biodegradability, biocompatibility and as a functional reinforcing agent. Conventional acid hydrolysis isolation of nanochitin requires high temperatures and acid concentration, time and energy. Herein, for the first time, microwave irradiation method was used as an eco-friendly approach to isolate nanochitin from different sources. The isolation conditions were optimized through an experimental Box-Behnken design using surface response methodology. The data showed optimal conditions of 1 M HCl, 10.00 min and 124.75 W to obtain lobster nanocrystals; 1 M HCl, 14.34 min and 50.21 W to obtain shrimp nanocrystals; and 1 M HCl, 29.08 min and 54.08 W to obtain squid pen nanofibres, reducing time and HCl concentration. The obtained isolation yields where of 85.30, 79.92 and 80.59 % for lobster, shrimp and squid, respectively. The morphology of the nanochitins was dependent of the chitin origin, and the lengths of the nanochitins were of 314.74, 386.12 and > 900 nm for lobster, shrimp and squid pen, respectively. The thermal stability of the ensuing nanochitins was maintained after treatment. The results showed that nanochitin could be obtained by using an eco-friendly approach like microwave irradiation.The authors would like to thank the Basque Government (scholarship of young researchers training and project IT1008-16) for supporting financially this research and their gratitude for technical and human support provided by SGIker (UPV/EHU/ERDF, EU). S.C.M.F. is the recipient of an E2S UPPA Research Partnership Chair (MANTA: Marine Materials) supported by the “Investissements d’Avenir” French program managed by ANR (ANR-16-IDEX-0002), the R ́egion Nouvelle-Aquitaine and the Communaut ́e d’Agglom ́eration du Pays Basque, France

Subglacial floods beneath ice sheets.

As, in the market, poly (lactic acid) (PLA) is the most used polymer as an alternative to conventional plastics, and as functionalized chitin nanocrystals (CHNC) can provide structural and bioactive properties, their combination sounds promising in the preparation of functional nanocomposite films for sustainable packaging. Chitin nanocrystals were successfully modified via acylation using anhydride acetic and dodecanoyl chloride acid to improve their compatibility with the matrix, PLA. The nanocomposite films were prepared by extrusion/compression approach using different concentrations of both sets of functionalized CHNC. This investigation brings forward that both sets of modified CHNC act as functional agents, i.e., they slightly improved the hydrophobic character of the PLA nanocomposite films, and, very importantly, they also enhanced their antifungal activity. Nonetheless, the nanocomposite films prepared with the CHNC modified with dodecanoyl chloride acid presented the best properties.The authors are thankful for the financial support from the European Commission through the European Project ECLIPSE (NMP-280786); the Department of Education of the Basque Government through project IT1008-16; and scholarship of young researchers training and project. The authors also acknowledge the technical and human support of General Research Services (SGIker) from the UPV/EHU for water vapor transmission and oxygen transmission analyses