Degradation kinetic study of cholesterol lowering statin drug using sono-hybrid techniques initiated by metal-free polymeric catalyst

Abstract

Abstract The present study addressed the degradation kinetics of cholesterol lowering statin drug using metal-free polymeric catalyst g-C3N4 synthesized through sonochemical method followed by thermal condensation. The photocatalytic experiments were performed to assess the catalytic activity of the synthesized g-C3N4 catalyst. The results revealed that the g-C3N4 possesses high oxidation properties and able to degrade ∼93% of lovastatin within a short span of time 10 min under sono-hybrid technique with a rate constant of 15.1 × 10–2 min–1. On the other hand, the maximum synergy index was attained when the ultrasound was applied with g-C3N4 nanoparticles. A significant enhancement of 2.25 folds higher degradation efficiency was achieved as compared to the sonolysis process alone. This enhancement is due to the addition of catalyst which facilitates more nucleation sites for cavitation bubbles and promoted cavitation phenomenon in the system. The study of adsorption and oxidation processes revealed that the degradation of lovastatin was primarily by oxidation reaction. When the experiments were performed at low pH, a significant degradation was observed – which is due to the formation of hydronium ions (H3O+). This H3O+ produces alternative and reactive species such as •OH, •O, HO 2 • in the presence of free electrons in the reaction solution. The maximum synergy was seen for (US+g-C3N4) process followed by (US+g-C3N4+H2O2+UVC) and (US+UVC). The experimental results of stability and reusability of the catalyst also confirmed that the catalyst could be easily regenerated and reused for several times without losing any catalytic activity – which might be useful for reducing the total operating cost for a wastewater treatment plant.