Degradation of 2-methylisoborneol in water by hydroxyl radical

二-甲基异莰醇(2-MIB)是一种由蓝绿藻以及放线菌等微生物产生,具有桥环结构的饱和叔醇,在水中具有令人厌恶的土霉味,常规水处理工艺难以对其氧化; 降解.利用大气压强电离放电生成羟基自由基(·OH),对2-MIB进行氧化降解,确定了其氧化剂剂量效应、时间效应关系,并利用GC-MS对2-MIB; 氧化降解过程中间产物的分析,推断其氧化降解机制.结果表明:对初始浓度为150,300ng/L的2-MIB,分别投加总氧化剂TRO1.8,2.3m; g/L,接触反应6s去除率分别为96%和97.6%,处理后残余浓度低于10ng/L; (低于人类嗅阈值).在2-MIB水样中加入·OH淬灭剂叔丁醇(TBA)后,2-MIB的去除效果明显降低,证明氧化降解2-MIB的主要为·OH.另; 外通过对氧化降解过程中间产物分析表明,·OH能破坏2-MIB的桥环结构,并最终矿化生成CO_2和H_2O.2-methylisoborneol (2-MIB) produced by cyanobacteria and actinomycetes; is a saturated bicyclic-tertiary alcohol, which can cause earthy/musty; taste and odor in surface water. Moreover, 2-MIB is usually difficult to; be decomposed and removed by conventional water treatment process. In; this paper, hydroxyl radical (·OH) generated by a strong ionization; discharge process at atmosphere pressure was used to degrade 2-MIB in; water, of which the removal efficiency including dose effects and; contact reaction time were investigated. The intermediate products; formed in ·OH treatment process were analyzed by GC-MS, and the; oxidative degradation mechanism of 2-MIB by ·OH was discussed. Results; show that the removal rate for 2-MIB with initial concentration of 150; and 300ng/L could reach 96% and 97.6% within 6.0s, while the total; reactive oxidant (TRO) dose were 1.8 and 2.3mg/L, respectively. After; ·OH treatment, the concentration of 2-MIB in water was lower than 10ng/L; (lower than the human olfactory threshold). The degradation effects of; 2-MIB were obviously reduced by the ·OH scavengers tertiary butyl; alcohol (TBA), indicating that ·OH should be the main oxidant for 2-MIB; oxidative degradation. By analyzing the intermediates produced in the; oxidative degradation process, it was found that the bridge ring; structures of 2-MIB could be destroyed by ·OH and finally mineralized to; CO_2 and H_2O.国家科技支撑计划项目; 国家重大科研仪器研制项目; 科技部创新人才推进计划重点领域创新团队; 辽宁省重点实验室基础研究项

高藻饮用水系统中羟基自由基降解诺氟沙星

在厦门翔安水厂12000t/d常规饮用水处理工艺的基础上建立了\"混凝沉淀-砂滤-·OH/NaClO氧化降解抗生素及消毒-清水池\"的处理系统,在九龙江流域高藻爆发期完成了工程化试验.结果表明,当砂滤出水总藻密度为2.04×103cells/mL时,注入相同氧化剂剂量0.5mg/L处理20s后,·OH将56ng/L的诺氟沙星降解至未检出,而NaClO仅降解至54ng/L.·OH在氧化降解抗生素的同时能杀灭全部藻细胞.根据HPLC-MS/MS检测到的降解中间产物分析,·OH氧化降解诺氟沙星通过进攻哌嗪环、萘啶环和氟原子破坏药效团,直至矿化为CO2和H2O.·OH消毒后不产生消毒副产物,检测的106项指标均达到国家《生活饮用水卫生标准》（GB 5749-2006）,为我国高藻饮用水中抗生素的安全处理提供技术支撑.国家重大科研仪器研制项目(NSFC:61427804);;科技部创新人才推进计划重点领域创新团队(2015RA4008);;国家自然科学基金资助重大研究计划(91441132

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies