Pollutant removal from wastewater by a functionalized membrane based on poly(2,6-dimethyl-1,4-phenylene)oxide (PPO)

Emerging contaminants in wastewater are becoming a serious concern, posing significant risks to aquatic ecosystem and human life. In this context different strategies have been introduced over the years, but adsorption is getting a lot of interest because it is not expensive, is easy to perform, easy to scale up, and adsorbents can also be regenerated and reused. The development of new, high performance adsorbent materials is crucial for effective contaminant removal. Although various polymers have been explored for this purpose, recent attention has shifted toward materials able to form nanoporous crystalline (NC) phases. Among them, the commercially available poly(2,6 dimethyl 1,4 phenylene)oxide (PPO) stands out as particularly promising, exhibiting remarkably fast pollutant uptake even from highly dilute aqueous solutions. In this communication PPO films with NC phases will be used to remove contaminants from water. Moreover, since functionalization can be a very promising way to better enhance adsorption properties to improve both hydrophilicity of the polymer and electrostatic interaction with the contaminants present in wastewater, the sulfonation of PPO was performed and the adsorption kinetics and contaminants uptake were studied. Higher kinetics uptake has been obtained by using sulfonated PPO, and especially the NC functionalized films (NC SPPO) have shown the highest kinetics with respect to the other films involved in this study. This remarkable result is due to the sulfonated groups present in the PPO amorphous phase, indeed by enhancing hydrophilicity, and by exposing anionic groups, it can both improve the diffusion of the guest molecules and, further to this, it promotes the removal of cationic contaminants by electrostatic interactions.