Sustainable Electrospun Affinity Membranes for Water Remediation by Removing Metal and Metal Oxide Nanoparticles

Nanoparticles (NPs) as part of engineered nanomaterials (ENMs) possess outstanding properties. Thus, they are more frequently integrated into various products resulting in high annual production quantities. The consequence can be the unintentional release into the environment where NPs could accumulate and pose a threat to human health. Therefore, the strong need becomes apparent for the remediation of environmental media. Electrospun nonwovens, which are defined here as membranes, could efficiently remove these released NPs. In this paper, electrospun membranes are utilized to flow filtration of metal and metal oxide NP, such as gold, silver, copper oxide, zinc oxide, iron oxide, and titanium dioxide. The membrane–NP interaction was analyzed and the correlation between NP size, NP ligand, ligand concentration, and the membrane surface functional group was investigated systematically. Finally, a membrane combining two functional groups was designed, which is able to adsorb up to 100% of the filtered NPs. The highest adsorption capacity was provided by AuNPs with 0.14 mg NP/mg membrane. To enhance their lifetime and gain sustainability, the membranes were then regenerated three times by rinsing with low concentrated acids. No significant efficiency loss was recorded, which allowed reusability of the electrospun membranes. We believe that the results shown here are of general relevance for other metals, metal oxides, and microplastic particles as well.