Controllable preparation of supramolecular coordination polymers based on carboxylated pillar[n]arenes and zinc ions: An efficient tool for paraquat removal from water

Supramolecular coordination polymers Zn2+@WP5 and Zn2+@WP6 have been designed and controllable pre-pared through coordination interaction between pillar[n]arenes (carboxylated pillar[5]arenes (WP5) and carboxylated pillar[6]arenes (WP6)) and zinc ions. Taking advantages of the host-guest interaction between pillar[n]arenes and paraquat (PQ), Zn2+@WP5 and Zn2+@WP6 can adsorb PQ efficiently. In particular, in comparison with Zn2+@WP6, Zn2+@WP5 can achieve the separation of PQ efficiently, mainly benefiting from its high surface area. The adsorption ability of Zn2+@WP5 was explored systematically including adsorption ki-netics, thermodynamic adsorption analysis as well as the influence of pH and ionic strength. The maximum adsorption capacity of PQ was about 203.60 mg/g. In addition, Zn2+@WP5 could be regenerated and efficiently adsorb PQ in tap and river water sample. This work extends the application of pillar[n]arenes-based supramo-lecular coordination polymers in micro-pollutants separation and removal.