Emerging organic contaminants (EOCs) in the water bodies pose a great threat to the ecosystem. EOCs are generally found in raw domestic wastewater and hospital wastewater, and they also found in treated wastewater due to ineffective secondary treatment in wastewater treatment plants (WWTPs). Moreover, the persistence of EOC in aquatic matrices for a relatively longer duration generates eco-toxicity and antibacterial resistance genes (ARGs). Advanced oxidation processes (AOPs) are widely used for the generation of reactive oxygen species (ROS) for the treatment of EOCs. However, high energy and material cost limits its applicability. Piezoelectric nanomaterials have great potential to reduce the cost of the process and overcome the drawbacks of different AOPs. This research was focused on the development of novel piezocatalytic technology for the removal of EOCs.

In this research, piezocatalytic heterojunctions (type-I MoS2/NaNbO3 and type-II g-C3N4/NaNbO3) were developed and tested under ultrasonication for the removal of a model antibiotic, i.e., metronidazole (MET). It was observed that optimized flower like morphology of MoS2 (MSNF) in heterojunction (MSNF(30)/NaNbO3) shown a maximum MET removal of ~92%. Effect of pH and competitive anions on the piezocatalytic activity was evaluated to understand the screening effect on efficiency of the process. Finally, intermediates formed during the piezocatalysis and toxicity of aqueous solution after treatment were analysed. On the other hand, the COMSOL simulation was performed to understand the piezoelectric effect generated under mechanical force. Overall, ultrasonic assisted piezoelectric effect induced electrocatalytic reactions, and played a role in enhancing the removal efficiency.

MSNF(30)/NaNbO3 based piezocatalytic thin-film nanocomposite nanofiltration (TFN-NF) membrane was synthesized and applied for water treatment. The Optimized piezocatalytic membrane showed improvement in the antifouling properties of membrane with flux recovery ratio improved from 66% to 85% under applied water pressure. In addition, self-cleansing mechanism of the TFN-NF due to piezoelectric activity induced under water pressure was also tested. This seminar will highlight the major findings and also summarize the work on MSNF(30)/NaNbO3 based piezocatalysis and TFN-NF application for water/wastewater treatment.