Removal of Aliphatic Amines by NiLa-Layered Double Hydroxide Nanostructures

Dimethylamine (DMA) and diethylamine (DEA) as precursors for the formation of potentially N-nitrosamines are widespread in the environment, and the removal of these disinfection byproduct precursors from water is of great significance to control the quality of drinking water. In this study, a three-dimensional hierarchical NiLa-layered double to remove them from a synthetic solution and real surface water. NiLa-LDH nanoplatelets endowed the biochar with an improved porous structure, high functional groups, and more active metal sites. NiLa-LDH/BC exhibited a high DMA and DEA adsorption capacity of 46.45 and 40.10 mg g-1, which is 6.31 and 7.85 times higher than that of BC, respectively. A fixed-bed column experiment revealed that NiLa-LDH/BC could last for similar to 1860 to 2400 bed volumes (BVs) before a breakthrough occurred (approximately 9 times higher than that of BC). In addition, the leaching test and regeneration and toxicity test of Daphnia magna demonstrate the high stability (over 88% adsorption capacity after seven adsorption-desorption cycles), extremely low metal leaching (<0.01 mg g-1), and low toxicity (24h-EC50 and 48h-EC50 of the NiLa-LDH/BC leachates were 13.07 and 6.33%, respectively). According to material characterization, the main removal mechanism of DMA and DEA by NiLa-LDH/BC was electrostatic attraction, hydrogen bonding, and complexation. Density functional theory calculations were also applied to evaluate the DMA and DEA adsorption performance of materials. Overall, this study indicated that three-dimensional hierarchical NiLa-LDH/ BC can be promising in highly efficient removal of N-nitrosamine precursors from real surface water.

Automated summary

In this study, three-dimensional hierarchical NiLa-LDH/BC was used for the highly efficient removal of N-nitrosamine precursors DMA and DEA from water. The material exhibited high adsorption capacity, stability, and low toxicity, and the removal mechanism involved electrostatic attraction, hydrogen bonding, and complexation.