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 m(2)/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 pi-pi 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 degrees 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 pi-pi 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.