Efficient Solar-Driven Degradation of Naphthenic Acids in Aqueous Solutions and Real Oil Sands Process Water Using a Novel Immobilized ZnO Nanorod Reactor

The large volumes of oil sands process water (OSPW) generated during bitumen extraction present significant environmental concerns due to the presence of toxic organic contaminants, particularly naphthenic acids (NAs). Therefore, effective and sustainable treatment strategies are urgently required to enable OSPW remediation. In this work, in situ-fabricated zinc oxide nanorods (ZnO NRs) were immobilized on a glass surface and applied for the first time for the solar-driven photocatalytic degradation of model and natural NAs. Over 95.0% of six model NAs in water were degraded using the ZnO NR-coated glass container after 10 h of simulated solar radiation. Furthermore, over 93.0% removal of classical NAs (O 2 –NAs) in real OSPW was achieved within 16 h under the same reaction conditions. Notably, comparable degradation efficiencies were achieved under natural solar radiation. The ZnO NR-coated vial exhibited good reusability and stability, maintaining an 88.3% degradation efficiency of O 2 –NAs after four reuse cycles. In addition, seed germination assays confirmed reduced phytotoxicity in treated OSPW, as evidenced by improved germination and plant growth compared with untreated OSPW. These findings highlight immobilized ZnO NRs as an environmentally friendly and sustainable approach for OSPW remediation, offering a practical strategy to mitigate the environmental impact of industrial process waters.