Highly efficient and reusable lanthanum-carbon nanotube films for enhanced phosphate removal

The removal of phosphorus (P) from aquatic environments using lanthanum-based materials has recently garnered increasing attention. However, the separation and recovery of adsorbents still face important challenges. In this study, a novel lanthanum-carbon nanotube (La-CNT) film was designed, and its phosphate sorption performance was investigated under different conditions, including the adsorbent dosage, initial P concentration, contact time, and initial solution pH. The La-CNT films also presented a high phosphate adsorption capacity over a wide pH range and high concentrations of competitive anions. Electrostatic attraction, surface precipitation, and ligand exchange were identified as the main phosphate adsorption mechanisms of La-CNT films. Besides, the films could remove phosphate to levels below 10 μg/L even in water with low phosphate concentrations. Apart from the excellent P capture performance of the La-CNT films, its high P recovery and good reusability make it a promising adsorbent.