Pd/activated carbon sorbents for mid-temperature capture of mercury from coal-derived fuel gas

Higher concentrations of Hg can be emitted from coal pyrolysis or gasification than from coal combustion, especially elemental Hg. Highly efficient Hg removal technology from coal-derived fuel gas is thus of great importance. Based on the very excellent Hg removal ability of Pd and the high adsorption abilities of activated carbon（AC） for H2 S and Hg, a series of Pd/AC sorbents was prepared by using pore volume impregnation, and their performance in capturing Hg and H2 S from coal-derived fuel gas was investigated using a laboratory-scale fixed-bed reactor. The effects of loading amount, reaction temperature and reaction atmosphere on Hg removal from coal-derived fuel gas were studied. The sorbents were characterized by N2 adsorption, X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）. The results indicated that the efficiency of Hg removal increased with the increasing of Pd loading amount, but the effective utilization rate of the active component Pd decreased significantly at the same time. High temperature had a negative influence on the Hg removal. The efficiency of Hg removal in the N2-H2S-H2-CO-Hg atmosphere（simulated coal gas） was higher than that in N2-H2S-Hg and N2-Hg atmospheres, which showed that H2 and CO, with their reducing capacity, could benefit promote the removal of Hg. The XPS results suggested that there were two different ways of capturing Hg over sorbents in N2-H2S-Hg and N2-Hg atmospheres.     

Enhanced cyanogen chloride formation after UV/PS and UV/H2O2 pre-oxidation and chlorination in natural river water

Ultraviolet/persulfate (UV/PS) and Ultraviolet/hydrogen peroxide (UV/H₂O₂) have attracted much attention in recent years as advanced oxidation processes for water treatment. However, it is not all clear how these two methods affect the formation of cyanogen chloride (CNCl) in the subsequent water chlorination process. In this study, it was found that both UV/H₂O₂ and UV/PS pre-oxidation promoted the formation of CNCl in six actual water samples collected from urban rivers. Glycine, uric acid, arginine and histidine were investigated as the model compounds to explore the effects of different methods on the production of CNCl. The results showed that compared with chlorination alone, pre-oxidation by UV/H₂O₂ and UV/PS can reduce the production of CNCl for glycine and uric acid by up to 95% during post-chlorination process. However, they can greatly promote the formation of CNCl for arginine and histidine by up to 120-fold. In a more detailed investigation, pre-oxidation of histidine formed highly reactive intermediates to chlorine, leading to increased CNCl formation and chlorine consumption. The results showed that the precursors of CNCl was altered after pre-oxidation, and need to be re-evaluated.     

Experimental and theoretical studies on NO selective catalytic oxidation over α-MnO2

Based on the experimental and theoretical methods, the NO selective catalytic oxidation process was proposed. The experimental results indicated that lattice oxygen was the active site for NO oxide over the $\mathrm{\alpha }$-MnO₂(110) surface. In the theoretical study, DFT (density functional theory) and periodic slab modeling were performed on an $\mathrm{\alpha }$-MnO₂(110) surface, and two possible NO oxidation mechanisms over the surface were proposed. The non-defect $\mathrm{\alpha }$-MnO₂(110) surface showed the highest stability, and the surface O_s (the second layer oxygen atoms) position was the most active and stable site. O₂ molecule enhanced the joint adsorption process of two NO molecules. The reaction process, including O₂ dissociation and O=N-O-O-N=O formation, was calculated to carry out the NO catalytic oxidation mechanism over $\mathrm{\alpha }$-MnO₂(110). The results showed that NO oxidation over the $\mathrm{\alpha }$-MnO₂(110) surface exhibited the greatest possibility following the route of O=N-O-O-N=O formation. Meanwhile, the formation of O=N-O-O-N=O was the rate-determining step.     

基于地统计模型的上海大气污染物多建模方法的比较

地统计模型被广泛应用于环境空气污染物暴露模拟,但不同建模方法及其模拟结果之间的对比研究较少.基于上海2016~2019年55个环境空气监测点位的NO₂和PM_2.5观测数据,以及交通路网、排放源兴趣点和卫星数据等地统计变量,应用偏最小二乘回归（PLS）、监督学习线性回归（SLR）和机器学习随机森林（RF）这3种建模方法创建年暴露模型,并进一步应用普通克里金插值（OK）法分析模型残差,构建复合模型.应用交叉验证对模型的模拟效果进行检验,选取每一种建模方法的最优模型结构（是否应用OK）作为最终模型.结果表明,NO₂模型中表现最好的是RF-OK （R_mse²为0.70~0.82）和PLS-OK模型（R_mse²为0.78~0.84）;PM_2.5模型中PLS模型（R_mse²为0.62~0.71）优于SLR-OK （R_mse²为0.40~0.79）和RF-OK （R_mse²：0.31~0.56）模型.应用3种建模方法对上海1 km网格开展年暴露模拟和对比,NO₂模型间模拟结果的相关性（r为0.82~0.91）高于PM_2.5模拟结果的相关性（r为0.66~0.96）.基于3种模型2019年的模拟结果,评估了上海NO₂和PM_2.5的人群暴露水平.     

4-氯苯酚在水溶液中的光化学反应(Ⅰ)单线态氧和自由基的产生

在模拟太阳光照射下，４氯苯酚（４ＣＰ）浓度迅速降低，反应过程对应着产生大量的单线态氧和自由基．金属离子Ｆｅ２＋、Ｆｅ３＋、Ａｌ３＋能够加速这一过程，尤以Ｆｅ２＋、Ｆｅ３＋的影响更明显；在模拟太阳光照射下，向４ＣＰ体系加入的富里酸（ＦＡ），对４ＣＰ浓度降低略起抑制作用，这表明二者之间存在相互作用．但当再加入金属离子Ｆｅ２＋、Ｆｅ３＋、Ａｌ３＋后，能够加速４ＣＰ浓度降低，尤以Ｆｅ２＋、Ｆｅ３＋的影响更显著．     

氧化亚氮在森林和草原中的地-气交换

采用箱式法,建立了一套完整的测定森林草原土壤Ｎ２Ｏ排放方法,并对我国北方的自然环境中Ｎ２Ｏ排放作了观测,得出其最大排放通量为２３μｇ／（ｍ＾２·ｈ）。并发现森林草原土壤当温度低于１５℃时对Ｎ２Ｏ有吸收行为,其最大吸收通量为１８．９８４μｇ（ｍ＾２·ｈ）。     

几种粘土矿物对Pb~(2+)的吸附作用及其主要影响因素的探讨

对土壤中常见的三种粘土矿物对Pb2+的吸附作用及其主要影响因素进行了探讨。结果表明，三种粘土矿物对Pb2+的吸附能力顺序为：蒙脱石＞伊利石＞高岭石。蒙脱石对Pb2+的吸附受pH的强烈影响，pH高有利于对Pb2+的吸附。与蒙脱石形成复合体形式的有机化合物的存在不利于蒙脱石对Pb2+的吸附。     

Fenton氧化法预处理垃圾渗滤液试验研究

采用Fenton氧化法处理长沙市黑糜峰垃圾填埋场垃圾渗滤液原液,考察了影响COD去除率的各种因素,包括初始pH值、FeSO4·7H2O投加量、双氧水投加量、反应时间及投加方式等,试验结果表明:在初始pH值为3、FeSO4·7H2O投加量为0.5%、双氧水投加量为18 mL/L、反应时间为100 min、投加方式为3次投加的条件下,可使垃圾渗滤液原液的COD去除率达40%左右,并提高了生化比,为后续生物处理改善了条件.     

氮氟掺杂二氧化钛(N,F-TiO2)的制备及可见光催化活性的研究

以氨水为氮源,氢氟酸为氟源,采用溶胶-凝胶法制备了氮氟掺杂二氧化钛(N,F-TiO2)光催化剂,并通过X-射线衍射(XRD)和扫描电镜(SEM)技术对其晶型和形态进行表征.最后以酸性红B为模型污染物,探讨了N和F加入量、焙烧温度、焙烧时间、照射时间、催化剂用量、溶液初始浓度和照射功率等因素对N,F-TiO2可见光催化活性的影响.结果表明,制备的N,F-TiO2以锐钛型为主,N和F的掺杂对TiO2的晶相没有明显改变,但可以扩大TiO2的可见光响应范围.当N和F的加入量均为2.0%,且在500℃下焙烧40 min时,得到的N,F-TiO2的可见光催化活性明显高于单N或单F掺杂的TiO2(N-TiO2或F-TiO2).对于50 mL浓度为10.0 mg·L-1的酸性红B溶液,当催化剂加入量为1.5 g·L-1,128W光照3.0 h,溶液pH=5.6时,去除率为85.40%.适当延长光照时间至4.0 h,降解率几乎可达100%.另外,研究还证明了N,F-TiO2催化可见光降解过程中有.OH自由基生成.     

四溴双酚A在鲫鱼不同器官中的分布、富集及病理研究

研究了将鲫鱼(Carassius auratus)长期暴露于不同浓度的四溴双酚A(TBBPA)后的器官组织分布和浓缩富集系数,同时对不同暴露时间的鲫鱼不同器官病理切片进行了观察.结果显示,各浓度组鲫鱼肝脏和肾脏的TBBPA含量都表现出先升高后下降的趋势,鳃和肌肉中TBBPA含量只有在高浓度时呈现相同的趋势.病理切片显示鲫鱼肝脏、肾脏和鳃等器官组织均表现出时间-剂量依赖性的病理损伤,在相同暴露浓度下,雄鱼的性腺损伤程度高于雌鱼.