Quaternization of porphyrin conjugated organic polymer as an effective photocatalyst for fast degradation of 2,4-D and BPA

Conjugated organic polymers (COPs) originating from porphyrin and perylene bisimide exhibit promising capacity as photocatalysts benefiting from their inherent semiconducting characteristics, but most of them suffer from the hydrophobic properties, which strongly hinder their surface reactions and photocatalytic performance. To solve this problem, the quaternary ammonium groups were introduced into the porous skeleton of a COP-based photocatalyst (PDIN-Py) through Friedel-Crafts alkylation & Menschutkin reactions to yield a super-hydrophilic COP, denoted as PDIN-PyN+. Apart from the hydrophilicity, such post-modification strategy also enhances the visible light utilization, boosts the photogenerated carriers transport and endows PDIN-PyN+ with more positive zeta potential (21.9 mV), thus enhancing the electrostatic interaction with target anionic model pollutants including bisphenol A (BPA) and 2,4-dichlorophenoxyacetic acid (2,4-D) and improving the photocatalytic degradation performance. The removal efficiency (η) of PDIN-PyN+ towards 2,4-D (150 ppm) and BPA (20 ppm) can reach >99 % within 30 min under the irradiation of visible light, and the PDIN-PyN+ also exhibits excellent reusability and withstands various environmental influencing factors, thereby it shows great potential in real-water treatment scenarios.