Graphene oxide based ultrafiltration membranes for photocatalytic degradation of organic pollutants in salty water
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Pastrana Martínez, Luisa María; Morales Torres, Sergio; Figueiredo, José L.; Faria, Joaquim L.; Silva, Adrián M.T.Editorial
Elsevier
Fecha
2015-06Referencia bibliográfica
Published version: Water Research Volume 77, 15 2015, Pages 179-190. https://doi.org/10.1016/j.watres.2015.03.014
Patrocinador
Financial support for this work was provided by project NORTE-07-0202-FEDER-038900 (NEPCAT), financed by FEDER (Fundo Europeu de Desenvolvimento Regional) through ON2 (Programa Operacional do Norte) and QREN, and by project PTDC/AAC-AMB/122312/2010, co-financed by FCT (Fundação para a Ciência e a Tecnologia) and FEDER through Programme COMPETE (FCOMP-01-0124-FEDER-019503). This work was partially co-financed by FCT/MEC and FEDER under Programe PT2020 (Project UID/EQU/50020/2013), and by QREN, ON2 and FEDER through project NORTE-07-0124-FEDER-000015. LMPM and SMT acknowledge financial support from FCT grants SFRH/BPD/88964/2012 and SFRH/BPD/74239/2010, respectively. AMTS acknowledges the FCT Investigator 2013 Programme (IF/01501/2013), with financing from the European Social Fund and the Human Potential Operational Programme. Technical assistance by Dr. Carlos Sá and CEMUP team with SEM analysis is gratefully acknowledged.Resumen
Flat sheet ultrafiltration (UF) membranes with photocatalytic properties were prepared with lab-made TiO2 and graphene oxide-TiO2 (GOT), and also with a reference TiO2 photocatalyst from Evonik (P25). These membranes were tested in continuous operation mode for the degradation and mineralization of a pharmaceutical compound, diphenhydramine (DP), and an organic dye, methyl orange (MO), under both near-UV/Vis and visible light irradiation. The effect of NaCl was investigated considering simulated brackish water (NaCl 0.5 g L−1) and simulated seawater (NaCl 35 g L−1). The results indicated that the membranes prepared with the GOT composite (M-GOT) exhibited the highest photocatalytic activity, outperforming those prepared with bare TiO2 (M−TiO2) and P25 (M-P25), both inactive under visible light illumination. The best performance of M-GOT may be due to the lower band-gap energy (2.9 eV) of GOT. In general, the permeate flux was also higher for M-GOT probably due to a combined effect of its highest photocatalytic activity, highest hydrophilicity (contact angles of 11°, 17° and 18° for M-GOT, M−TiO2 and M-P25, respectively) and higher porosity (71%). The presence of NaCl had a detrimental effect on the efficiency of the membranes, since chloride anions can act as hole and hydroxyl radical scavengers, but it did not affect the catalytic stability of these membranes. A hierarchically ordered membrane was also prepared by intercalating a freestanding GO membrane in the structure of the M-GOT membrane (M-GO/GOT). The results showed considerably higher pollutant removal in darkness and good photocatalytic activity under near-UV/Vis and visible light irradiation in continuous mode experiments.