1 Laboratory of Separation and Reaction Engineering-Laboratory of Catalysis and Materials (LSRE-LCM), Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal. vilar@fe.up.pt.
2 Nanotechnology and Bio-Engineering Research Group, Department of Environmental Science, Faculty of Science, Institute of Technology Sligo, Ash Lane, Sligo, Ireland.
3 Plataforma Solar de Almería, Carretera Senés Km 4, 04200, Almería, Spain.