Solar–driven simultaneous degradation of dimethyl and diethyl phthalate using NH2–UiO66(Ce/Zr)–derived ZrO2/TiO2 photocatalysts: Mechanistic insight and detoxification

Phthalate esters (PAEs), including dimethyl phthalate (DMP) and diethyl phthalate (DEP), are priority emerging contaminants that commonly coexist in aquatic environments and pose significant ecological and human health risks. Herein, a series of NH 2 –UiO66(Ce/Zr)–derived ZrO 2 /TiO 2 heterostructured photocatalysts were synthesized via a solvothermal–calcination route using NH 2 –UiO66(Ce/Zr) as the precursor and evaluated for the simultaneous solar–driven degradation of DMP and DEP. Structural characterization revealed that the incorporation of MOF–derived Ce/Zr into TiO 2 reduced crystallite size, increased surface area, promoted interfacial charge transfer, and suppressed electron–hole recombination. Among the prepared materials, NU–Ce/Zr–T10 exhibited the highest photocatalytic activity, achieving 89.6% DMP removal, 96.9% DEP removal, and 56.7% total organic carbon (TOC) reduction after 5 h of simulated solar irradiation. Compared with the Ce–free counterpart (NU–Zr–T10), the enhanced performance was attributed to cerium's role in controlling crystal growth, facilitating charge separation, and improving interfacial redox processes. Electrochemical impedance spectroscopy, photoluminescence, and Mott–Schottky analyses confirmed the superior charge–transfer characteristics of the heterostructure. Reactive species trapping experiments showed that ● O 2 − , ● OH, and h + participated synergistically in the degradation process, with superoxide radicals playing the predominant role. GC–MS analysis revealed degradation pathways involving hydroxylation, de–esterification, aromatic ring opening, and the formation of low–molecular–weight carboxylic acids. Importantly, ECOSAR predictions and Vibrio fischeri bioassays confirmed progressive detoxification of the treated effluent, while the photocatalyst maintained high activity and structural stability after three reuse cycles. These findings demonstrate that NH 2 –UiO66(Ce/Zr)–derived ZrO 2 /TiO 2 heterostructures constitute an effective and environmentally safe platform for the simultaneous degradation, mineralization, and detoxification of phthalate–contaminated waters under solar irradiation.