Highly sensitive and low-cost detecting and recovering Ce3+ from ammonia nitrogen wastewater using bio-inspired nanochannel/membrane

The increasing demand for monitoring and recovering rare earth elements (REE) has driven the development of new strategies for detection and enrichment of lanthanide metal ions. In this study, we were inspired from ligand-responsive ion channels in cell membrane to construct artificial single nanochannels and multipore membranes for achieving for the first time ultra-sensitive detection and environmentally friendly recovery of Ce3+ from ammonia nitrogen wastewater which is the most common wastewater. A single conical nanochannel with polyelectrolyte functionalization was developed, wherein polyacrylic acid (PAA) played a crucial role by providing affinity carboxyl groups that form complexes with Ce3+. This interaction led to a measurable change in the ion rectification factor within the asymmetric nanochannel, enabling the ultra-sensitive detection of Ce3+. Under optimized experimental conditions, the rectification factor exhibited a proportional relationship with the logarithm of Ce3+ concentration, covering linear ranges of 1 nM − 1 × 103 nM and 1 μM − 500 μM, with a detection limit of 1 nM. To evaluate the applicability of this method for real sample analysis, the Ce3+ content in ammonia nitrogen water samples was determined. The results demonstrated the excellent performance of the proposed method for detecting Ce3+ with the minimum recovery percentage of 95.0 %. The theoretical calculations further confirmed that PAA exhibits the highest binding energy with Ce3+, reinforcing its importance in the detection process. Additionally, multipore membranes were designed based on the same principle for the recovery of Ce3+ from ammonia nitrogen wastewater. Impressively, the recovery rate reached 91.97%. Considering the similarity among REEs, the recyclable detection method presented in this study can not only monitor and recovery Ce3+ but also holds great significance for all REEs detection and resource reuse.