Porous Polycalix[4]arenes for Fast and Efficient Removal of Organic Micropollutants from Water

Organic micropollutants are hazards to the environment and human health. Conventional technologies are often inefficient at removing them from wastewater. For example, commercial activated carbon (AC) exhibits slow uptake rates, limited capacities, and is costly to regenerate. Here, we report the utility of porous calix[4]arene-based materials, CalPn (n = 2-4), for water purification. Calixarenes are a common motif in supramolecular chemistry but have rarely been incorporated into extended, porous networks such as organic polymers. CalPn exhibit pollutant uptake rates (k_obs) and adsorption capacities (q_max) that are among the highest reported. For example, the k_obs of CalP4 for bisphenol A (BPA) is 2.12 mg/g·min, which is significantly higher (16 to 240 times) than k_obs for ACs and 1.4 times higher than that of the most efficient material previously reported; the q_max of CalP4 for BPA is 403 mg/g. The CalPn polymers can be regenerated several times, with performance levels left undiminished, by a simple wash procedure that is less energy intensive than that required for ACs. These findings demonstrate the potential of calixarene-based materials for organic micropollutant removal.