TY - JOUR
T1 - Interfacial photothermal water evaporator based on nanoporous microwave-expanded graphite and coconut waste fibers@recycled polystyrene as substrate
AU - Ovando-Medina, Víctor M.
AU - Escobar-Villanueva, Alondra G.
AU - Martínez-Gutiérrez, Hugo
AU - González-Ortega, Omar
N1 - Publisher Copyright:
© 2020 John Wiley & Sons Ltd
PY - 2020/10/25
Y1 - 2020/10/25
N2 - Solar water evaporators (SWE) have shown growing interest due to their capacity to transform sunlight to thermal energy. In this work, SWE were prepared based on microwave-expanded graphite as light absorber deposited onto an ecological porous substrate obtained by casting a mixture of coconut fibers and recycled polystyrene. The materials were characterized by SEM, FTIR and UV/Vis-NIR spectroscopies, and thermogravimetric analyses. It was observed that the light absorber film presented high and wide light absorption in the solar electromagnetic spectrum and increased superficial area when compared to the unexpanded graphite film counterpart. Nanopores between 400 and 900 nm and microcavities in the 200 to 500 μm range were formed at the surface of the SWE after 6 seconds of microwave exposure, which are destroyed at higher exposure times. SWE of laboratory scale diameter were tested for water evaporation at different light intensities, microwave expanding time, and thicknesses to determine their effects on evaporation rate and efficiency. It was observed that SWE rates increased from 1.09 ± 0.006 to 1.73 ± 0.007 kg h−1 m−2 for unexpanded and expanded graphite through 6 seconds, respectively; being the latter the best SWE reaching 91.5% of efficiency at 1200 W m−2 of illumination. This efficiency was stable after reaching the maximum stable efficiency in only 15 minutes. The scaling-up of the process was studied in a SWE of 6.1 cm in diameter using a bigger glass cell in the presence of pure water or simulated seawater (3.5% NaCl), achieving efficiencies of 89.8% and 86.1%, respectively.
AB - Solar water evaporators (SWE) have shown growing interest due to their capacity to transform sunlight to thermal energy. In this work, SWE were prepared based on microwave-expanded graphite as light absorber deposited onto an ecological porous substrate obtained by casting a mixture of coconut fibers and recycled polystyrene. The materials were characterized by SEM, FTIR and UV/Vis-NIR spectroscopies, and thermogravimetric analyses. It was observed that the light absorber film presented high and wide light absorption in the solar electromagnetic spectrum and increased superficial area when compared to the unexpanded graphite film counterpart. Nanopores between 400 and 900 nm and microcavities in the 200 to 500 μm range were formed at the surface of the SWE after 6 seconds of microwave exposure, which are destroyed at higher exposure times. SWE of laboratory scale diameter were tested for water evaporation at different light intensities, microwave expanding time, and thicknesses to determine their effects on evaporation rate and efficiency. It was observed that SWE rates increased from 1.09 ± 0.006 to 1.73 ± 0.007 kg h−1 m−2 for unexpanded and expanded graphite through 6 seconds, respectively; being the latter the best SWE reaching 91.5% of efficiency at 1200 W m−2 of illumination. This efficiency was stable after reaching the maximum stable efficiency in only 15 minutes. The scaling-up of the process was studied in a SWE of 6.1 cm in diameter using a bigger glass cell in the presence of pure water or simulated seawater (3.5% NaCl), achieving efficiencies of 89.8% and 86.1%, respectively.
KW - coconut waste fibers
KW - nanoporous expanded graphite
KW - photothermal
KW - recycled polystyrene
KW - solar water evaporation
UR - http://www.scopus.com/inward/record.url?scp=85088979923&partnerID=8YFLogxK
U2 - 10.1002/er.5773
DO - 10.1002/er.5773
M3 - Artículo
AN - SCOPUS:85088979923
SN - 0363-907X
VL - 44
SP - 10878
EP - 10893
JO - International Journal of Energy Research
JF - International Journal of Energy Research
IS - 13
ER -