1. Department of Chemical Engineering, E.T.S.E.I., University of Vigo, Rúa Maxwell s/n, 36310 Vigo, Spain, Department of Chemical Engineering, University of Santiago de Compostela, Rúa Lope Gómez de Marzoa s/n, 15782 Santiago de Compostela, Spain, and Department of Chemical, Environmental and Materials Engineering, University of Jaén, 23071 Jaén, Spain