Tuning the Surface Area and Pore Size of Pyrene–Biphenyl-Coupled Hypercross-linked Polymers to Capture Toxic Organic Pollutants

Hypercross-linked polymers with suitable binding sites and porosities are promising materials for environmental remediation and removal of pollutants Herein, three porous organic hypercross-linked polymers (HCP-1, HCP-2, and HCP-3) are tailored by varying the molar ratio of pyrene (PY) and biphenyl precursors via a one-pot Friedel–Crafts alkylation reaction between pyrene (PY) and bis(1,4-dichloromethyl)biphenyl (BCB) using ferric chloride as a Lewis acid catalyst. HCP-1, HCP-2, and HCP-3 displayed surface areas of 296, 264, and 698 m2/g, respectively, with multiple micro- and mesopores in the polymeric network. Due to the variation in the surface area, the presence of abundant pores, and strong π–π interacting abilities, the obtained HCPs displayed excellent removal capacities toward pollutants of different natures like polyaromatic hydrocarbons [naphthalene (NAP)], persistent organic pollutants [dichlorodiphenyldichloroethylene (DDE)], pharmaceutical pollutants [carbamazepine (CAR)], and plasticizer micropollutants [bisphenol-A (BPA)]. Interestingly, HCP-3 showed a faster removal rate toward NAP (99% within 10 min) and DDE (95% within 10 min) at 25 °C. Though HCP-3 showed faster removal capacities toward NAP and DDE, HCP-1 and HCP-2 displayed the maximum uptake capacities for NAP as 455 mg/g and 527 mg/g, respectively, due to the presence of abundant complement π–π stacking led by PY and BCB units in the polymeric network. In contrast, HCP-3 showed better removal capacities toward CAR (130 mg/g) and BPA (99 mg/g) than other HCPs. It is worth mentioning that HCPs displayed very good NAP and DDE removal capacities over a wide pH range due to the pH-insensitive nature of pollutants and HCPs.