Adsorption and degradation of multiple micropollutants with trace concentrations by porous Zr-porphyrin metal-organic frameworks with missing linker defects in water

Metal-organic frameworks (MOFs) are effective photocatalysts with high surface area and excellent visible light absorption. In this study, a kind of Zr-porphyrin (PCN-134) and its derivatives PCN-134(Fe) and PCN-134 (Cu) were prepared for removing six structurally diverse micropollutants with extremely low concentrations (100 μg/L). The initial adsorption rates for five selected pharmaceuticals (antipyrine (AT), sulfadimethoxypyrimidine (SSM), clofibric acid (CA), diclofenac (DF), and ibuprofen (IBU)) ranged from 174.5 μg/(g • min) to 2256.5 μg/(g • min) over PCN-134 (Cu), which is 1.2–2.5 times higher than those of PCN-134. A series of optical and photoelectric properties were studied using Mott−Schottky plots, UV–Vis diffuse reflectance spectrum (UV-DRS), and transient photocurrent intensity analysis. PCN-134 (Fe) successfully extended the visible-light absorption edges at around 750 nm. PCN-134 and PCN-134 (Fe) were favorable for generating •O₂⁻ with E_CB values calculated at −1.04 eV and - 0.55 eV by Mott−Schottky plots and UV–Vis diffuse reflectance spectrum (UV-DRS). The incorporation of metals enhanced the charge separation properties of PCN-134. The transient photocurrent intensity of PCN-134 (Fe) was 3.1 times higher than that of PCN-134 (Cu). The degradation efficiency for naproxen (NPX) over PCN-134 (Fe) for antipyrine (AT) and clofibric acid (CA) was 2.4 times and 11.3 times higher than those over the pristine PCN-134. •O₂⁻ and ¹O₂ could be the major ROS produced, confirmed by quenching experiments and electron paramagnetic resonance (EPR) technologies. This study offers useful guidance to improve the current materials for water purification.