Photocatalytic activity of PANI/CoAl–LDH heterojunctions towards efficient degradation of propranolol: Degradation pathways and toxicity assessment

Abstract

Herein, a novel PANI/CoAl-LDH (PCL) heterojunction photocatalyst was synthesized by combining CoAl-layered double hydroxides (CoAl-LDH) and polyaniline (PANI) fibers wrapped with β-cyclodextrin (β-CD). The PCL photocatalyst exhibited excellent photocatalytic activity and was applied for the first time in the photocatalytic degradation of propranolol (PRO), achieving a removal efficiency of 91.8%. The reaction rate constants of 7% PANI/CoAl-LDH (7-PCL) were 2.83 times and 8.92 times greater than those of the CoAl-LDH and PANI systems. The exceptional performance is mainly attributed to its minimal recombination rate and high photogenerated carrier efficiency. The migration efficiency of photoinduced charge carriers was markedly improved by the incorporation of polyaniline. Additionally, β-CD can separate the electron/hole recombination pathway, reducing the recombination probability. Consequently, more electrons are directed to CoAl-LDH, generating more superoxide radicals for the efficient mineralization of PRO molecules. Subsequently, potential degradation pathways for PRO were proposed based on the density functional theory (DFT) analyses and liquid chromatography-mass spectrometry (LC-MS), and the majority of the intermediates were found to be environmentally friendly. The current investigation provides a promising strategy for constructing high-efficiency heterojunction photocatalysts to degrade PRO contaminants.