1. Department of Chemical Engineering, University of Patras, University Campus, Caratheodory 1, GR-26504, Patras, Greece 2. Department of Chemistry, Laboratory of Physical Chemistry, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece 3. PSA (Plataforma Solar de Almería), CIEMAT, Crta Senés km 4, Tabernas, Almería, 04200, Spain