title: Radiation induced decomposition of a refractory cefathiamidine intermediate.
abstract: Diisopropylthiourea (DPT), an intermediate of a widely used cephalosporin, has been found to be one of the most refractory components in cephalosporin synthesis wastewater. This compound cannot be completely removed by conventional biological processes due to its antimicrobial property. Ionizing radiation has been applied in the decomposition of refractory pollutants in recent years and has proved effective. Therefore, the decomposition of DPT by γ-irradiation was studied. The compound was irradiated at the dose of 150-2000 Gy before a change of concentration and UV absorption of the solutions was detected. Furthermore, the decomposition kinetics and radiation yield (G-value) of DPT was investigated. The results of radiation experiments on DPT-containing aqueous showed that the DPT can be effectively degraded by γ-radiation. DPT concentration decreased with increasing absorbed doses. G-values of radiolytic decomposition for DPT (20 mg/L) were 1.04 and 0.47 for absorbed doses of 150 and 2000 Gy, respectively. The initial concentration and pH of the solutions affected the degradation. As the concentration of substrate increased, the decomposition was reduced. The decrease of removal rate and radiation efficacy under alkaline condition suggested that lower pH values benefit the γ-induced degradation. UV absorption from 190 to 250 nm decreased after radiation while that from 250 to 300 nm increased, indicating the formation of by-products.
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: qbr10@mails.tsinghua.edu.cn.
authors.forename: Qiburi
authors.initials: Q
authors.lastname: Bao
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China; Zhejiang Provincial Key Laboratory of Water Science and Technology, Jiaxing 314006, China. Electronic address: chenlj@tsinghua.edu.cn.
authors.forename: Lujun
authors.initials: L
authors.lastname: Chen
authors.affiliation: Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China.
authors.forename: Jianlong
authors.initials: J
authors.lastname: Wang
mesh_terms: D002511:Cephalosporins / Q000138:chemical synthesis; D005720:Gamma Rays; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D014508:Urea / Q000031:analogs & derivatives* / Q000528:radiation effects*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000528:radiation effects*
chemical_list: D002511:Cephalosporins; D014874:Water Pollutants, Chemical; C000597420:diisopropylthiourea; C018866:cefathiamidine; D014508:Urea
keywords: Decomposition; Diisopropylthiourea; Ionizing radiation; Wastewater