Degradation of N-nitrosodimethylamine (NDMA) and its precursor dimethylamine (DMA) in mineral micropores induced by microwave irradiation. (1st May 2016)

• Record Type: Journal Article
• Authors: He, Yuanzhen; Cheng, Hefa
• Is Part Of: Water research. Volume 94(2016)
• Page Start: 305
• Page End: 314
• Publication Date: 2016-05-01
• Subjects: N-nitrosodimethylamine (NDMA) -- Dimethylamine (DMA) -- Sorption -- Microporous mineral -- Microwave-induced degradation -- Water treatment; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2016.02.065
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: Removal of N -nitrosodimethylamine (NDMA) in drinking water treatment poses a significant technical challenge due to its small molecular size, high polarity and water solubility, and poor biodegradability. Degradation of NDMA and its precursor, dimethylamine (DMA), was investigated by adsorbing them from aqueous solution using porous mineral sorbents, followed by destruction under microwave irradiation. Among the mineral sorbents evaluated, dealuminated ZSM-5 exhibited the highest sorption capacities for NDMA and DMA, which decreased with the density of surface cations present in the micropores. In contrast, the degradation rate of the sorbed NDMA increased with the density of surface cations under microwave irradiation. Evolutions of the degradation products and C/N ratio indicate that the sorbed NDMA and DMA could be eventually mineralized under continuous microwave irradiation. The degradation rate was strongly correlated with the bulk temperature of ZSM-5 and microwave power, which is consistent with the mechanism of pyrolysis caused by formation of micro-scale "hot spots" within the mineral micropores under microwave irradiation. Compared to existing treatment options for NDMA removal, microporous mineral sorption coupled with microwave-induced degradation has the unique advantages of being able to simultaneously remove NDMA and DMA and cause their full mineralization, and thus could serve as a promising alternative method. Graphical abstract: Highlights: A novel method for simultaneous removal of NDMA and its precursor DMA was developed. Dealuminated ZSM-5 zeolites exhibited high sorption capacities for NDMA and DMA. The sorbed NDMA and DMA could be fully mineralized under microwave irradiation. Microwave causes formation of "hot spots" and pyrolysis of NDMA sorbed in micropores. Size and surface chemistry of mineral pores control NDMA sorption and its degradation.