NDMA adsorption and degradation by a new-type of Ag-MONT material carrying nanoscale zero-valent iron

Abstract

Nitrosamines, which are emerging nitrogenous disinfection by-products, have raised great concern owing to their carcinogenicity and genotoxicity. Thus, exploring efficient materials to remove nitrosamines from the environment is of vital importance. In this work, NaBH4 was taken as a reducing agent and Ag-based metal organic nanotubes (Ag-MONTs) were impregnated in FeSO4·7H2O to prepare nanoscale zero-valent iron (nZVI) supported on the nanotubes (nZVI@Ag-MONTs). The new material was then characterized and applied to N-dimethylnitrosamine (NDMA) adsorption and degradation in water. The material had excellent ability to adsorb and degrade NDMA, and the total concentrations of iron and silver remaining in water did not exceed standard limits after 120 min of adsorption. Coexisting substances, such as NO3−, Cl−, CO32−, humic acid, trichloromethane, and trichloronitromethane, did not affect the NDMA removal efficiency of the adsorbent. The NDMA removal efficiency of the new material exceeded 88% even in the presence of SO42− and PO43−. The NDMA degradation mechanism of nZVI@Ag-MONTs included a catalytic hydrogenation reaction and resulted in dimethylamine as the final degradation product. The nZVI@Ag-MONTs showed favorable stability and reusability. Taking the results together, the nZVI@Ag-MONTs proposed in this work are applicable to NDMA adsorption and degradation in water.