中心组合设计优化S-Cr-TiO2催化剂光降解工艺条件

在确定的温度和光照条件下,采用中心组合设计法研究了固相反应法合成的硫与铬共掺杂二氧化钛(S-Cr-TiO2)光催化剂与水溶苯胺蓝(ANB)可见光降解过程中的三个作用因子:催化剂的浓度、水溶苯胺蓝水溶液的pH值及其初始浓度之间的相互作用关系,得到了影响因子与降解速率之间的回归方程及因素之间相互作用的响应面图.结果表明,S...     

大气痕量挥发性有机物碳同位素分析研究进展

对于大气痕量挥发性有机物的研究,浓度测量方法在满足科学研究的要求方面尚有欠缺,相比之下,同位素测量方法具有测量精度高、对源解析准确和测量误差小的特点且发展迅速,该方法在大气痕量挥发性有机物的研究中所起到的作用日益显著;但由于同位素测量技术对大气样品质量的要求很高,故目前该方法在大气环境科学的研究领域中还不能普及,今后随...     

Beyond hypoxia：Occurrence and characteristics of black blooms due to the decomposition of the submerged plant Potamogeton crispus in a shallow lake

Organic matter-induced black blooms(hypoxia and an offensive odor) are a serious ecosystem disasters that have occurred in some large eutrophic shallow lakes in China. In this study, we investigated two separate black blooms that were induced by Potamogeton crispus in Lake Taihu, China. The main physical and chemical characteristics, including color- and odor-related substances, of the black blooms were analyzed. The black blooms were characterized by low dissolved oxygen concentration(close to 0 mg/L), low oxidation-reduction potential, and relatively low pH of overlying water. Notably higher Fe2+and∑S2-were found in the black-bloom waters than in waters not affected by black blooms. The black color of the water may be attributable to the high concentration of these elements, as black FeS was considered to be the main substance causing the black color of blooms in freshwater lakes. Volatile organic sulfur compounds, including dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide, were very abundant in the black-bloom waters. The massive anoxic degradation of dead Potamogeton crispus plants released dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide, which were the main odor-causing compounds in the black blooms. The black blooms also induced an increase in ammonium nitrogen and soluble reactive phosphorus levels in the overlying waters. This extreme phenomenon not only heavily influenced the original lake ecosystem but also greatly changed the cycling of Fe, S, and nutrients in the water column.     

Unregulated emissions from diesel engine with particulate filter using Fe-based fuel borne catalyst

The alteration and formation of toxic compounds and potential changes in the toxicity of emissions when using after-treatment technologies have gained wide attention. Volatile organic compound（VOC）, carbonyl compound and particle-phase polycyclic aromatic hydrocarbon（PAH） emissions were tested at European Steady State Cycle（ESC） to study unregulated emissions from a diesel engine with a fuel-borne catalyst and diesel particulate filter（FBC–DPF）. An Fe-based fuel-borne catalyst was used for this study. According to the results, brake specific emissions of total VOCs without and with DPF were 4.7 and4.9 mg/kWh, respectively, showing a 4.3% increase. Benzene and n-undecane emissions increased and toluene emission decreased, while other individual VOC emissions basically had no change. When retrofitted with the FBC–DPF, total carbonyl compound emission decreased 15.7%, from 25.8 to 21.8 mg/kWh. The two highest carbonyls, formaldehyde and acetaldehyde, were reduced from 20.0 and 3.7 to 16.5 and 3.3 mg/kWh respectively. The specific reactivity（SR） with DPF was reduced from 6.68 to 6.64 mg/kWh. Total particle-phase PAH emissions decreased 66.4% with DPF compared to that without DPF. However, the Benzo[a]pyrene equivalent（BaPeq） with DPF had increased from 0.016 to 0.030 mg/kWh.Fluoranthene and Pyrene had the greatest decrease, 91.1% and 88.4% respectively. The increase of two- and three-ring PAHs with DPF indicates that the fuel-borne catalyst caused some gas-phase PAHs to adsorb on particles. The results of this study expand the knowledge of the effects of using a particulate filter and a Fe-based fuel-borne catalyst on diesel engine unregulated emissions.     

Carbonyl emissions from heavy-duty diesel vehicle exhaust in China and the contribution to ozone formation potential

Fifteen heavy-duty diesel vehicles were tested on chassis dynamometer by using typical heavy duty driving cycle and fuel economy cycle. The air from the exhaust was sampled by 2,4- dinitrophenyhydrazine cartridge and 23 carbonyl compounds were analyzed by high performance liquid chromatography. The average emission factor of carbonyls was 97.2 mg/km, higher than that of light-duty diesel vehicles and gasoline-powered vehicles. Formaldehyde, acetaldehyde, acetone and propionaidehyde were the species with the highest emission factors. Main influencing factors for carbonyl emissions were vehicle type, average speed and regulated emission standard, and the impact of vehicle loading was not evident in this study. National emission of carbonyls from diesel vehicles exhaust was calculated for China, 2011, based on both vehicle miles traveled and fuel consumption. Carbonyl emission of diesel vehicle was estimated to be 45.8 Gg, and was comparable to gasolinepowered vehicles （58.4 Gg）. The emissions of formaldehyde, acetaldehyde and acetone were 12.6, 6.9, 3.8 Gg, respectively. The ozone formation potential of carbonyls from diesel vehicles exhaust was 537 mg O3/km, higher than 497 mg O3/km of none-methane hydrocarbons emitted from diesel vehicles.     

冬季东海、南黄海中DMS和DMSP浓度分布及影响因素研究

于2011年12月~2012年1月现场测定了东海、南黄海表层海水中二甲基硫(DMS)及其前体物质二甲巯基丙酸内盐(DMSP分为溶解态DMSPd和颗粒态DMSPp)的含量,研究了它们的浓度分布规律及其影响因素,并对DMSPp的粒级分布和DMS的海-气通量进行了探讨.结果表明,表层海水中DMS、DMSPd和DMSPp的浓度分别在0.58~4.14、0.37~7.86和4.29~25.76 nmol·L-1之间,平均值分别为(2.20±0.82)、(2.12±1.66)和(11.98±6.23)nmol·L-1.DMS、DMSPp与叶绿素a(Chl-a)呈现明显的正相关关系,并且它们的周日变化趋势基本一致,说明浮游植物生物量是影响研究海域内DMS和DMSP生产分布的关键因素.另外,DMSPd浓度和总细菌丰度表现出一定的负相关,这可能是在细菌释放的DMSP裂解酶的作用下DMSPd会发生裂解生成DMS.研究发现,5~20μm的微型浮游植物是海区内Chl-a和DMSPp的主要贡献者.此外,冬季东海、南黄海表层海水DMS的海-气通量在0.61~25.52μmol·(m2·d)-1之间,平均值为(8.30±5.92)μmol·(m2·d)-1.     

硫铁比对再生水深度脱氮除磷的影响

为了考察硫铁比对反硝化脱氮同步除磷效果的影响,进行了不同硫铁比的反硝化脱氮除磷静态实验,并对复合填料系统反硝化脱氮同步除磷作用进行了分析.结果表明,硫铁复合填料的脱氮除磷效果均显著高于单一填料;硫铁比是影响复合填料反硝化脱氮除磷效果的一个关键因素,当硫铁比(体积比)大于等于1∶1时,TN、TP去除率分别达到了85%和97%以上.复合填料脱氮除磷过程均满足二级动力学方程,系统脱氮作用主要依赖于异养反硝化和硫自养反硝化过程,而除磷主要由于海绵铁腐蚀产生的化学除磷作用.     

饥饿对硫自养反硝化反应器生物群落结构的影响

采用颗粒硫磺/白云石和黄铁矿/白云石自养反硝化反应器处理二沉尾水,探究饥饿忍耐对反应器去除效果、微生物群落变化的影响及其性能恢复时间.结果表明,在12~14℃的低温条件下,经过30 d的不进水饥饿忍耐后,颗粒硫磺/白云石和黄铁矿/白云石反应器出水NO_3~--N浓度分别从1.78 mg·L~(-1)、11.32 mg·L~(-1)增加到27.87 mg·L~(-1)、26.56 mg·L~(-1).颗粒硫磺/白云石和黄铁矿/白云石自养反硝化反应器分别在重启后的第5 d和11 d使得NO_3~--N去除性能恢复至饥饿前的水平,并且在低温条件下保持了良好的脱氮效果.MiSeq高通量测序结果表明,2个反应器的细菌群落的丰度和多样性饥饿期均低于恢复期,且优势菌门均为Proteobacteria,主要的纲类为β-Proteobacteria.硫磺/白云石反应器中鉴别出Thiobacillus菌属为主要反硝化类群.     

微生物燃料电池处理含S2-/NH4+废水的研究

以除硫硝化微生物燃料电池(Microbial Fuel Cell,MFC)处理含S~(2-)/NH_4~+的模拟无机废水,研究了不同进水S~(2-)浓度下MFC的产电性能、污染物去除效果和阳极室硫累积情况.结果表明,除硫硝化MFC可实现同步阳极除硫和阴极硝化,并通过非生物电化学作用和生物电化学作用共同产电.进水S~(2-)浓度为(60.8±2.9)、(131.7±2.4)、(161.7±4.5)和(198.1±3.1)mg·L~(-1)时,最佳阳极碳刷清洗周期分别为3、3、3、4个换水周期,前3个进水浓度下的换水周期可分别缩短为6、8和8 h.MFC阴极硝化完全,不受进水S~(2-)浓度影响,但氧从阴极向阳极的渗漏导致阳极库仑效率较低(40%).适当增加进水S~(2-)浓度可增强MFC的产电性能并提高S~(2-)去除负荷和颗粒硫累积比.除硫硝化MFC适宜的进水S~(2-)浓度为(161.7±4.5)mg·L~(-1),相应的最大功率密度为5.77 W·m~(-3),周期产电量为(141.0±5.2)C,S~(2-)去除负荷为(0.31±0.00)g·L~(-1)·d~(-1),颗粒硫累积比达58%.阳极碳纤维丝上沉积有粒径约100 nm的颗粒硫.阳极悬浮物与沉积物相比,悬浮物中S0含量比例较高,而S6+含量比例较低.     

新型转式垃圾焚烧过程中脱氯脱硫机理的研究

为了探讨有机垃圾焚烧过程钙基添加剂对HCl，SO_x生成特性的影响，分别在自行设计的中空水冷转式垃圾焚烧炉和固定床加热炉中进行了一系列的实验，研究结果表明新型转式焚烧炉具有强化传热传质特性，能提高HCl、SO_x的脱除率，可抑制有害气体的生成；同时也研究了 HCl，SO₂气体同时存在时，钙基添加剂对脱氯脱硫效率的影响规律。