Synthesis of Pd–ZnO-porous carbon photocatalyst and its application in rifampicin degradation for water remediation

Nanocomposite photocatalysts have attracted considerable attention for the removal of pharmaceutical pollutants from aquatic environments. In this work, a palladium-decorated ZnO supported on porous carbon (Pd/ZnO/PC) nanocomposite was successfully synthesized and applied for the photocatalytic degradation of rifampicin (Rif) under UV irradiation. Porous carbon was prepared via phosphoric acid activation of potato starch, followed by ZnO deposition through a precipitation method and Pd nanoparticle incorporation. Structural and morphological characterizations (XRD, FTIR, SEM, and TEM) confirmed the successful formation of a well-dispersed Pd/ZnO/PC nanocomposite. Optical analysis revealed a band gap energy of 3.48 eV, indicating efficient UV-light activation. Photocatalytic experiments demonstrated a high Rif degradation efficiency of 98.80% after 180 min under a low-power 16 W UV lamp. To elucidate the adsorption and interaction mechanisms, molecular dynamics simulations were performed. The results revealed that porous carbon exhibits the strongest adsorption affinity toward Rif, while ZnO provides a stable adsorption platform dominated by electrostatic and van der Waals interactions. Radial distribution function and mean square displacement analyses further confirmed favorable adsorption configurations and enhanced molecular mobility with increasing temperature. The combined experimental and theoretical findings highlight the synergistic roles of porous carbon adsorption, ZnO photocatalysis, and Pd-mediated charge separation in the efficient removal of rifampicin from water.