title: Graphene oxide based ultrafiltration membranes for photocatalytic degradation of organic pollutants in salty water.
abstract: 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.
authors: LCM - Laboratory of Catalysis and Materials - Associate Laboratory LSRE-LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors: Luisa M
authors: LM
authors: Pastrana-Martínez
authors: LCM - Laboratory of Catalysis and Materials - Associate Laboratory LSRE-LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors: Sergio
authors: S
authors: Morales-Torres
authors: LCM - Laboratory of Catalysis and Materials - Associate Laboratory LSRE-LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors: José L
authors: JL
authors: Figueiredo
authors: LCM - Laboratory of Catalysis and Materials - Associate Laboratory LSRE-LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors: Joaquim L
authors: JL
authors: Faria
authors: LCM - Laboratory of Catalysis and Materials - Associate Laboratory LSRE-LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal. Electronic address: adrian@fe.up.pt.
authors: Adrián M T
authors: AMT
authors: Silva
mesh_terms: D001391:Azo Compounds / Q000737:chemistry* / Q000528:radiation effects; D002384:Catalysis; D004396:Coloring Agents / Q000737:chemistry / Q000528:radiation effects; D004155:Diphenhydramine / Q000737:chemistry* / Q000528:radiation effects; D006108:Graphite / Q000737:chemistry*; D008027:Light; D008567:Membranes, Artificial; D000068357:Saline Waters; D014025:Titanium / Q000737:chemistry*; D014462:Ultrafiltration / Q000295:instrumentation*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000528:radiation effects; D018508:Water Purification / Q000379:methods*
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D008567:Membranes, Artificial; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; C100258:methyl orange; D006108:Graphite; D004155:Diphenhydramine; D014025:Titanium
keywords: Anti-fouling; Filtration; Graphene oxide; Photocatalytic membranes; Salty water; Water purification