Sustainable Photocatalytic Treatment of Real Pharmaceutical Wastewater Using a Novel ZnO/MIP-202(Zr) Bio-MOF Hybrid Synthesized via a Green Approach

Abstract

Metal–organic frameworks (MOFs) are promising materials for environmental remediation, particularly in photocatalysis. In this work, a novel ZMIP nanocomposite was fabricated by integrating MIP-202(Zr) bio-MOF with ZnO nanoparticles. For the first time, ZnO nanoparticles were green-synthesized using water lettuce extract and incorporated into MIP-202(Zr) via a mild hydrothermal route. The resulting hybrid was applied as a visible-light photocatalyst for carbamazepine (CBZ) degradation in real pharmaceutical wastewater. Structural analyses (XRD, FTIR, TEM, EDS) verified the successful incorporation of ZnO into the MIP-202(Zr) framework. The composite exhibited a narrowed bandgap of 2.74 ± 0.1 eV compared to 4.05 ± 0.06 eV for pristine MIP-202 and 3.77 ± 0.04 eV for ZnO, highlighting enhanced visible-light utilization in ZMIP. Operational parameters were optimized using response surface methodology, where CBZ removal reached 99.37% with 84.39% TOC mineralization under the optimal conditions (90 min, pH 6, 15 mg/L CBZ, 1.25 g/L catalyst). The catalyst maintained stable performance over five reuse cycles. Radical quenching and UHPLC-MS analyses identified the dominant reactive oxygen species and generated intermediates, elucidating the degradation mechanism and pathways. Beyond CBZ, the ZMIP photocatalyst effectively degraded other pharmaceuticals, including doxorubicin, tetracycline, paracetamol, and ibuprofen, achieving degradation efficiencies of 82.93%, 76.84%, 72.08%, and 67.71%, respectively. Application on real pharmaceutical wastewater achieved 78.37% TOC removal under the optimum conditions. Furthermore, the supplementation of the photocatalytic system by inorganic oxidants ameliorated the degradation performance, following the order KIO4 > K2S2O8 > KHSO5 > H2O2. Overall, ZMIP demonstrates excellent activity, reusability, and versatility, underscoring its potential as a sustainable photocatalyst for real wastewater treatment.