Ultrasound-assisted photocatalytic decomposition of rifadin with biochar and CNT-based NiCr layered double hydroxides

Modification of layered double hydroxides (LDHs) is known to be beneficial for boosting the consistent formation of reactive oxygen species (ROSs) and enhancing the photocatalytic process. Herein, a facile synthesis method for preparing carbon nanotube (CNT) and biochar (BC)-based NiCr LDH (NC) nanocomposites as a sonophotocatalyst for the efficient degradation of rifadin (RA) was provided. The formation of thin nanosheet structures of NC along with porous and nanotube structures of BC and CNT was well approved by scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM). The bandgaps of the nanocomposites and pristine LDH are determined by differential reflectance spectroscopy (DRS) analysis. Results unveiled that sonophotocatalysis presented high efficacy in comparison with sonocatalysis and photocatalysis. Under optimized conditions, a 15 mg L⁻¹ of RA at pH 8 treated with 1 g L⁻¹ of NiCr LDH/BC (NC/BC) demonstrated 80.3% sonophotocatalytic degradation during 90 min. To shed light on the durability and stability of NC/BC, four consecutive cycles were operated. The chemical structure and surface morphology of the reused catalyst were stable, revealed by SEM and Fourier transform infrared (FTIR) analyses. It is deduced that NC/BC is an advantageous sonophotocatalyst for the decomposition of emerging pharmaceuticals.