Treatment of Hydrophobic Polycyclic Aromatic Hydrocarbons and Toxicity Using GO-TiO2-Sr(OH)2/SrCO3 Nanocomposite via Photocatalytic Degradation

Abstract

In this study, the effects of increasing sun light irradiation time (30 min, 120 min, 240 min and 360 min), increasing photocatalytic power (10 W, 50 W and 100 W), increasing graphene oxide (GO) nanoparticle concentrations (2 mg/l, 4 mg/l and 8 mg/l), increasing titanium dioxide (TiO2) nanoparticle concentrations (1 mg/l, 3 mg/l, 6 mg/l and 9 mg/l), increasing GO-TiO2-Sr(OH)2/SrCO3 nanocomposite concentrations (1 mg/l, 2 mg/l and 4 mg/l) on the destructions of four hydrophobic polycyclic aromatic hydrocarbons (PAHs) in a real petrochemical industry wastewater in Izmir (Turkey) were investigated. The yields in more hydrophobic PAHs with high benzene rings [benzo[a]pyrene (BaP) and benzo[k]fluoranthene (BkF)] were as high as the less hydrophobic PAHs with lower benzene rings [acenaphthylene (ACL) and carbazole (CRB)]; at pH=7.0, at 22oC after 360 min sun light irradiation time, respectively. Maximum 97%ACL, 98%CRB, 98%BaP and 99%BkF PAHs removals was detected at 4 mg/l GO-TiO2-Sr(OH)2/SrCO3 nanocomposite concentration, under 100 mW/cm2 sun light intensity, at 100 W photocatalytic power, at 360 min sun light irradiation time, at pH=7.0 and at 22oC, respectively. The effective PAHs concentrations caused 50% mortality in Daphnia magna cells increased from initial EC50=342.56 mg/l to EC50=631.05 mg/l, at pH=7.0 and at 22oC after 360 min photocatalytic degradation time resulting in a maximum acute toxicity removal of 99.99%, at 4 mg/l GO-TiO2- Sr(OH)2/SrCO3 nanocomposite concentration. The Daphnia magna acute toxicity was significantly reduced.