Demonstration of hydrogen production from food industry wastewaters by solar photoreforming: From the laboratory to outdoors operation in panel reactors

Identifier:  imarina:9452293

Handle: https://hdl.handle.net/20.500.11797/imarina9452293

Authors:  Valencia-Valero, Laura Carolina; Simbana, Kevin A; Eleraky, Jonas E; Haponska, Monika; Puga, Alberto

Abstract:
The concept of hydrogen production by the photocatalytic reforming (photoreforming) of wastewaters is herein proven for food industry effluents, both in classic batch laboratory cells, and in panel reactors operated under natural sunlight. Initial screening and photocatalyst optimisation, performed employing glucose as a representative model oxygenated contaminant, guided the selection of the most appropriate metal/titania materials for the process. Different metals were compared as co-catalysts in M/TiO2 (M: Cu, Ag, Au or Pt). Enhanced hydrogen production was achieved for platinum as the co-catalyst, regardless of the deposition method used. A hydrothermally synthesised nanosized titania with a partly oxidised carbonaceous coating was compared to commercial anatase and the benchmark P25 anatase-rutile nanocomposite, proving advantageous performance for the former in basic media (> 4.5 mmol(H-2) g(cat)(-1) h(-1), c(glucose) = 5 % w/v, pH = 12, simulated sunlight). Similarly, the same material outperformed the P25 counterpart for real juice production wastewaters having high pH values. Finally, photoreforming of juice production wastewaters was demonstrated in a novel prototype panel reactor under outdoors solar irradiation over the course of two weeks. Regarding wastewater treatment, pH decreased significantly from ca. 11 to < 6 and conductivity also decreased from 2.4 to 1.9 mS cm(-1). Organic matter breakdown was confirmed by long-term decrease of chemical oxygen demand and by disintegration of solids. As a final proof of effectiveness of the solar photocatalytic process, daily gas production volumes observed remarkably paralleled sunlight irradiance.