Unveiling a ternary MOF-derived LDH nanoarchitecture utilized for photocatalytic degradation of Meropenem pharmaceutical contaminant from wastewater: Developing thorough chemical mechanism

In this work, two complementary synthesis routes were developed to prepare novel Ni-containing layered double hydroxide (LDH) catalysts. In Route 1, a trivalent-metal composite precursor was fabricated by compositing MIL-101(Cr) and MIL-88A(Fe) MOFs and subsequently converted into Ni-[MCr/MFe] LDH via Ni²⁺ incorporation. In Route 2, Ni-MCr LDH and Ni-MFe LDH were individually derived from MIL-101(Cr) and MIL-88A(Fe) in the presence of Ni²⁺ and then combined to Ni-MCr LDH/Ni-MFe LDH composite. The synthesized materials were systematically characterized and applied to meropenem (MER) removal through a combined adsorption–photocatalysis process. Catalytic performance was evaluated by varying catalyst dosage, MER initial concentration, solution pH, and reaction temperature. Under optimized conditions (50 mg catalyst, 25 mg/L MER, visible-light irradiation), Ni-[MCr/MFe] LDH achieved 98.1% MER degradation and maintained 93.4% efficiency after five cycles, while post-reaction XRD, FTIR, and ICP analyses confirmed structural stability, heterogeneity, and recyclability. Adsorption followed the pseudo-second-order kinetic model and Temkin isotherm, indicating a chemisorption-dominated mechanism, whereas photocatalytic degradation obeyed pseudo-first-order kinetics. A comprehensive and previously unreported MER degradation pathway was elucidated using HPLC–MS/MS, radical scavenger tests, intermediate identification, and literature comparison, demonstrating that Ni-[MCr/MFe] LDH is a robust, reusable, and synergistic platform for visible-light-driven remediation of persistent pharmaceutical pollutants.