title: Nitrogen conversion in relation to NH3 and HCN during microwave pyrolysis of sewage sludge.
abstract: The nitrogen conversions in relation to NH3 and HCN were investigated during microwave pyrolysis of sewage sludge. The nitrogen distributions and evolution of nitrogen functionalities in the char, tar, and gas fractions were conducted. The results suggested that the thermal cracking of protein in sludge produced three important intermediate compounds, including the amine-N, heterocyclic-N, and nitrile-N compounds. The deamination of amine-N compounds resulted from labile proteins cracking led to the formation of NH3 (about 7.5% of SS-N) between 300 and 500 °C. The cracking of nitrile-N and heterocyclic-N compounds in the tars from the dehydrogenation and polymerization of amine-N generated HCN (6.6%) from 500 to 800 °C, respectively. Moreover, the ring-opening of heterocyclic-N in the char and tar contributed to the release of NH3 accounting for about 18.3% of SS-N with the temperature increasing from 500 to 800 °C. Specifically, the thermal cracking of amine-N, heterocyclic-N and nitrile-N compounds contributed to above 80% of the total (HCN+NH3) productions. Consequently, it might be able to reduce the HCN and NH3 emissions through controlling the three intermediates production at the temperature of 500-800 °C.
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, SKLUWRE, HIT, Harbin 150090, China. hittianyu@163.com
authors.forename: Yu
authors.initials: Y
authors.lastname: Tian
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Zuo
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.forename: Yanni
authors.initials: Y
authors.lastname: Cui
authors.forename: Tao
authors.initials: T
authors.lastname: Tan
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry; D015392:Chemistry, Inorganic / Q000379:methods*; D005740:Gases / Q000737:chemistry; D006856:Hydrogen Cyanide / Q000737:chemistry*; D008872:Microwaves; D009584:Nitrogen / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D012722:Sewage / Q000737:chemistry*; D013638:Tars / Q000737:chemistry; D013696:Temperature; D013818:Thermogravimetry
chemical_list: D005740:Gases; D012722:Sewage; D013638:Tars; D002606:Charcoal; D006856:Hydrogen Cyanide; D000641:Ammonia; D009584:Nitrogen