Selective removal of organic dyes with smart pillar[5]arene-based PDMAEMA/PES beads

Access to safe and clean water is in high demand due to the consequences of climate change, the growing global population, and the anthropological activities that have an impact on many industrial sectors and their associated needs for water. However, traditional techniques for cleaning (waste)water have not yet been able to fully eliminate the so-called "emerging contaminants," such as organic dyes, which are now extensively utilised in the leather, paper, plastic, textile, and cosmetics sectors. In fact, because of their chemical permanence and toxicity, they pose a serious risk to human health. For this reason, research and development is currently underway to develop innovative, cutting-edge methods for remediating (waste)water1. This study successfully carried out and reported the synthesis and characterisation of a smart polymer (P5-QPDMAEMA), obtained through the quaternarization of PDMAEMA with a pillar[5]arene derivative2. The goal of this polymer was to combine the host-guest properties of the covalently linked pillararenes with the responsiveness of the PDMAEMA polymer. In addition, PES/P5-QPDMAEMA blended polymers were developed and employed with the standard Non-solvent Induced Phase Separation (NIPS) procedure, which was performed at different coagulation pH levels, to obtain functional beads. The polymeric structures and reactivity of all the final functional beads were examined using ATR-FTIR, XPS and SEM techniques; additionally, the adsorption performances in the removal of MB and MO, as representative cationic and anionic dyes, respectively, were assessed in water. For the beads with the best removal capabilities, calculations of adsorption kinetics and isotherms were performed. Finally, zwitterionic beads were obtained by the post-functionalization of PDMAEMA and P5-QPDMAEMA beads, and the adsorption behaviour towards the elimination of the aforementioned cationic and anionic dyes is also reported.