Removal of Aliphatic Amines by NiLa-Layered Double Hydroxide Nanostructures

Abstract

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 hydroxide/biochar nanocomposite (NiLa-LDH/BC) was prepared 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 ∼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-EC 50 and 48h-EC 50 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.

Effective Control of N-Nitrosamines Formation from Water by Layered Double Oxide/Biochar Spheres: Research on the Adsorption of Precursors

“…Taking the adsorption of DMA as an example, the binding energies of Ni 2p 3/2 and Ni 2p 1/2 decreased by 0.40 and 0.35 eV, respectively, suggesting that the interaction between the Ni of the LDO/BSs and adsorbates might have involved ligand–metal complexation . From the N 1s XPS spectra (Figures d and S18), after the adsorption of DMA on LDO/BSs, the binding energy (401.7 eV) attributed to the amino group on the biochar shifted to 402.0 eV; moreover, its peak area increased from 27.7% to 39.6%, which contributed to complexation of the Ni–NH– group . The strong interaction may cause LDO to have a better ability to remove multiple N -nitrosamine precursors.…”

“…32 From the N 1s XPS spectra (Figures 5d and S18), after the adsorption of DMA on LDO/BSs, the binding energy (401.7 eV) attributed to the amino group on the biochar shifted to 402.0 eV; moreover, its peak area increased from 27.7% to 39.6%, which contributed to complexation of the Ni−NH− group. 30 The strong interaction may cause LDO to have a better ability to remove multiple Nnitrosamine precursors. Furthermore, compared with that of N=C, the area percentage of −NH− decreased from approximately 38.2% to 35.9% after the adsorption of DMA, suggesting the occurrence of noncomplexing adsorption.…”

“…Furthermore, it was reported that Fe-modified activated carbon can improve the adsorption capacity of DEA . Our previous work also observed that NiLa-layered double hydroxide (LDH) strongly binds to DMA and DEA via a synergistic interaction of multiple forces . Nevertheless, relevant research has only demonstrated the effectiveness of materials on a single precursor in simulated water, and comprehensive studies that have effectively demonstrated the selective removal of adsorbents for different N -nitrosamine precursors in real water are lacking, making it difficult to evaluate their actual performance.…”

“…29 Our previous work also observed that NiLa-layered double hydroxide (LDH) strongly binds to DMA and DEA via a synergistic interaction of multiple forces. 30 Nevertheless, relevant research has only demonstrated the effectiveness of materials on a single precursor in simulated water, and comprehensive studies that have effectively demonstrated the selective removal of adsorbents for different N-nitrosamine precursors in real water are lacking, making it difficult to evaluate their actual performance. Currently, the understanding of the adsorption of N-nitrosamine precursors is limited, and it is challenging to achieve the effective selective adsorption of different Nnitrosamine precursors and establish general mechanisms in this regard.…”

Selective Hydrogenative Rearrangement of Furfural to Cyclopentanol over Alloyed Cu–Co Supported on Sulfur-Doped Coffee Biochar

“…into them, which could lead to high catalytic activity and selectivity . However, the LDH-derived catalysts usually appear as aggregated lumps, which have a negative impact on the mass transfer processes and the exposure of active sites in the catalytic reactions. , Therefore, grafting LDH precursors onto other supports with abundant space through in situ growth strategies could be beneficial for improving their catalytic performance.…”