Grape-like CNTs/BaTiO3 nanocatalyst boosted hydraulic-driven piezo-activation of peroxymonosulfate for carbamazepine removal

Both carbon nanotubes (CNTs) and piezoelectric materials can activate peroxymonosulfate (PMS). However, the activation of PMS by CNTs suffers from poor reusability while hydraulic-driven piezo-activation of PMS faces the problem of limited charge separation. To solve the above problems, grape-like CNTs/BaTiO3 (CNTs/BT) nano-catalyst with a Ti - C bond was prepared. Results indicated that hydraulic-driven CNTs/BT-PMS system offered remarkable carbamazepine removal efficiency (91.93%, 120 min) with satisfactory reusability. The energy consumption of PMS activation by CNTs/BT was only 39.33% and 26.59% of those by CNTs and BT, respectively. Piezoresponse force microscopy and finite element simulation further suggested that these superior performances were mainly responsible for the synergistic effects of CNTs and BT, leading to stronger piezoelectric response with efficient piezo-generated charge separation, which in turn improved the efficiency for producing reactive species. Notably, the built-in piezoelectric field of BT constantly replenished electrons to CNTs and effectively suppressed the destruction of CNTs caused by chemical oxidation. This durable composite might be a promising catalyst for PMS activation with potential utilization of residual hydraulic power during water treatment.