Green and solvent-free fabrication of conductive halloysite–polythiophene nanocomposites for the removal of organic pollutants from aqueous media

Abstract

Toxic pharmaceutical pollutants, such as nicotine, represent a significant threat to natural water sources due to their continuous discharge. To address this issue, clay minerals and their composites have demonstrated exceptional adsorptive and remedial capabilities for wastewater purification. This research focused on developing green clay-polymeric adsorbents for the efficient removal of pharmaceutical pollutants from industrial wastewater. The synthesis involves creating halloysite nanotube–polythiophene nanocomposites through a green and cost-effective method using vapour polymerization and a solvent-free, ball-milled technique for the adsorptive removal of nicotine from wastewater. The investigation evaluates the impacts of preparation, modification and environmental conditions on the adsorptive performance of these clay-based nanocomposites compared to pure polythiophene. The polymerization process was evaluated by varying the vapour polymerization holding time for a fixed amount of oxidant (FeCl3) and halloysite nanotube (HNT) to investigate the impacts of monomer vapour exposure time on the polymerization of nanocomposites. Following the characterization of the synthesized adsorbents using various methods, the study investigated the impacts of various parameters (e.g. adsorbent dosage, pH and contact time) on the adsorption capabilities of the materials on a laboratory scale. The results revealed that the incorporation of HNT improved the adsorbing performance of nanocomposites. The pH, absorbent concentration and contact time directly affect nicotine adsorption. Significantly, halloysite–polythiophene 3 with a 2 h polymerization duration demonstrated the maximum adsorption efficacy of 78.94% at pH 10 after a 24 h contact time. The environmentally friendly halloysite-based nanocomposite shows promising potential as an effective adsorbent for pharmaceutical pollutant (nicotine) removal from aquatic environments.