锐钛矿型二氧化钛的低温合成及其吸附除氟性能的研究

通过水解法在50℃低温条件下合成了锐钛矿型TiO₂,使用XRD、FT-IR、BET等方法对TiO₂进行了表征,并研究其对水中氟离子的吸附行为。结果表明:所合成锐钛矿型TiO₂比表面积达到278.93 m2/g,常温下对氟离子的最大吸附量为30.02 mg/g。吸附过程符合Langmuir等温线模型和准一级动力学模型,是自发性的吸热过程,吸附机理为静电吸引。     

干湿法结合工艺回收废弃SCR脱硝催化剂中的钛、钒和钨

利用干湿法结合工艺实现废弃SCR脱硝催化剂中Ti、V和W元素的高效分离和浸出,提出成套废弃SCR脱硝催化剂中Ti、V和W的回收技术。以废弃SCR脱硝催化剂为研究对象,优选Ti、V和W元素最佳浸出工况,研究硫酸溶解法回收TiO₂和有机萃取法回收V₂O₅和WO₃的回收率与纯度。结果表明:酸浸还原浸钒最优工艺条件为温度140℃,液固比30∶1;钠化焙烧浸钨最优工艺条件为煅烧温度750℃,反应物与Na₂CO₃配比（质量比）为1∶1.5,在以上条件下V、W浸出率分别达到97.6%、93.6%。利用硫酸溶解法回收得到的TiO₂产物主要以锐钛矿晶型存在形式,在最佳焙烧温度750℃下,TiO₂回收率达到97.17%,纯度为95.35%。利用有机萃取法回收得到的V₂O₅和WO₃产物的回收率和纯度分别为72.47%、75.43%和93.25%、78.26%。     

Regulated emission characteristics of in-use LNG and diesel semi-trailer towing vehicles under real driving conditions using PEMS

On-road driving emissions of six liquefied natural gas(LNG) and diesel semi-trailer towing vehicles(STTVs) which met China Emission Standard IV and V were tested using Portable Emission Measurement System(PEMS) in northern China.Emission characteristics of these vehicles under real driving conditions were analyzed and proved that on-road emissions of heavy-duty vehicles(HDVs) were underestimated in the past.There were large differences among LNG and diesel vehicles, which also existed between China V vehicles and China IV vehicles.Emission factors showed the highest level under real driving conditions, which probably be caused by frequent acceleration, deceleration, and start-stop.NOx emission factors ranged from 2.855 to 20.939 g/km based on distance-traveled and 6.719–90.557 g/kg based on fuel consumption during whole tests, which were much higher than previous researches on chassis dynamometer.It was inferred from tests that the fuel consumption rate of the test vehicles had a strong correlation with NOx emission, and the exhaust temperature also affected the efficiency of Selected Catalytic Reduction(SCR) aftertreatment system, thus changing the NOx emission greatly.THC emission factors of LNG vehicles were 2.012–10.636 g/km, which were much higher than that of diesel vehicles(0.029–0.185 g/km).Unburned CH_4 may be an important reason for this phenomenon.Further on-road emission tests, especially CH_4 emission test should be carried out in subsequent research.In addition, the Particulate Number(PN) emission factors of diesel vehicles were at a very high level during whole tests, and Diesel Particulate Filter(DPF)should be installed to reduce PN emission.     

中国工业园区绿色发展政策对比分析及对策研究

为了提升我国工业园区绿色发展水平,对目前我国工业园区发展历程、现状特征进行了分析,对工业园区绿色发展政策进行了梳理和对比,并结合工业园区绿色发展中存在的问题提出了对策建议.研究表明:①我国工业园区经历了快速发展、调整发展和科学发展等阶段,在经济发展、资源与能源优化利用、污染减排等方面成效显著.②我国工业园区绿色发展的相关政策主要体现在国家生态工业示范园区创建、园区循环化改造、国家低碳工业园区试点、绿色园区建设和UNIDO绿色工业园区创建等工作中,这些政策在推动主体、实施路径、侧重方向上各不相同又各有特色,对推动工业园区节能减排绩效明显.③目前,我国工业园区绿色发展存在的问题主要表现在重视程度有待提升、风险防范意识有待加强、创新能力有待提高等方面.为此,提出了我国工业园区绿色发展对策建议:积极践行绿色发展理念,推进园区绿色化、生态化、低碳化建设,实现经济环境双赢;注意环境风险防控,确保环境安全;创新管理机制,强化监督管理.      

Dynamic nano-Ag colloids cytotoxicity to and accumulation by Escherichia coli: Effects of Fe3+, ionic strength and humic acid

Released Ag ions or/and Ag particles are believed to contribute to the cytotoxicity of Ag nanomaterials, and thus, the cytotoxicity and mechanism of Ag nanomaterials should be dynamic in water due to unfixed Ag particle:Ag⁺ ratios. Our recent research found that the cytotoxicity of PVP-Ag nanoparticles is attributable to Ag particles alone in 3 hr bioassays, and shifts to both Ag particles and released Ag⁺ in 48 hr bioassays. Herein, as a continued study, the cytotoxicity and accumulation of 50 and 100 nm Ag colloids in Escherichia coli were determined dynamically. The cytotoxicity and mechanisms of nano-Ag colloids are dynamic throughout exposure and are derived from both Ag ions and particles. Ag accumulation by E. coli is derived mainly from extracellular Ag particles during the initial 12 hr of exposure, and thereafter mainly from intracellular Ag ions. Fe³⁺ accelerates the oxidative dissolution of nano-Ag colloids, which results in decreasing amounts of Ag particles and particle-related toxicity. Na⁺ stabilizes nano-Ag colloids, thereby decreasing the bioavailability of Ag particles and particle-related toxicity. Humic acid (HA) binds Ag⁺ to form Ag⁺-HA, decreasing ion-related toxicity and binding to the E. coli surface, decreasing particle-related toxicity. HA in complex conditions showed a stronger relative contribution to toxicity and accumulation than Na⁺ or Fe³⁺. The results highlighted the cytotoxicity and mechanism of nano-Ag colloids are dynamic and affected by environmental factors, and therefore exposure duration and water chemistry should be seriously considered in environmental and health risk assessments.     

An investigation of changes in water quality throughout the drinking water production/distribution chain using toxicological and fluorescence analyses

Changes in water quality from source water to finished water and tap water at two conventional drinking water treatment plants(DWTPs) were monitored.Beside the routine water quality testing,Caenorhabditis elegans-based toxicity assays and the fluorescence excitation–emission matrices technique were also applied.Both DWTPs supplied drinking water that met government standards.Under current test conditions,both the investigated finished water and tap water samples exhibited stronger lethal,genotoxic and reprotoxic potential than the relative source water sample,and the tap water sample was more lethal but tended to be less genotoxic than the corresponding finished water sample.Meanwhile,the nearly complete removal of tryptophan-like substances and newly generated tyrosine-like substances were observed after the treatment of drinking water,and humic-like substances were identified in the tap water.Based on these findings,toxic pollutants,including genotoxic/reproductive toxicants,are produced in the drinking water treatment and/or distribution processes.Moreover,further studies are needed to clarify the potentially important roles of tyrosine-like and humic-like substances in mediating drinking water toxicity and to identify the potential sources of these contaminants.Additionally,tryptophan-like fluorescence may be adopted as a useful parameter to monitor the treatment performance of DWTPs.Our observations provided insights into the importance of utilizing biotoxicity assays and fluorescence spectroscopy as tools to complement the routine evaluation of drinking water.     

Synergistic effects of Cu species and acidity of Cu-ZSM-5 on catalytic performance for selective catalytic oxidation of n-butylamine

In this work, a series of Cu-ZSM-5 catalysts with different SiO₂/Al₂O₃ ratios (25, 50, 100 and 200) were synthesized and investigated in n-butylamine catalytic degradation. The n-butylamine can be completely catalytic degradation at 350°C over all Cu-ZSM-5 catalysts. Moreover, Cu-ZSM-5 (25) exhibited the highest selectivity to N₂, exceeding 90% at 350°C. These samples were investigated in detail by several characterizations to illuminate the dependence of the catalytic performance on redox properties, Cu species, and acidity. The characterization results proved that the redox properties and chemisorption oxygen primarily affect n-butylamine conversion. N₂ selectivity was impacted by the Brønsted acidity and the isolated Cu²⁺ species. Meanwhile, the surface acid sites over Cu-ZSM-5 catalysts could influence the formation of Cu species. Furthermore, in situ diffuse reflectance infrared Fourier transform spectra was adopted to explore the reaction mechanism. The Cu-ZSM-5 catalysts are the most prospective catalysts for nitrogen-containing volatile organic compounds removal, and the results in this study could provide new insights into catalysts design for VOC catalytic oxidation.     

Ozone pollution characteristics and sensitivity analysis using an observation-based model in Nanjing, Yangtze River Delta Region of China

Ground-level ozone (O₃) has become a critical pollutant impeding air quality improvement in Yangtze River Delta region of China. In this study, we present O₃ pollution characteristics based on one-year online measurements during 2016 at an urban site in Nanjing, Jiangsu Province. Then, the sensitivity of O₃ to its precursors during 2 O₃ pollution episodes in August was analyzed using a box model based on observation (OBM). The relative incremental reactivity (RIR) of hydrocarbons was larger than other precursors, suggesting that hydrocarbons played the dominant role in O₃ formation. The RIR values for NO_X ranged from –0.41%/% to 0.19%/%. The O₃ sensitivity was also analyzed based on relationship of simulated O₃ production rates with reductions of VOC and NO_X derived from scenario analyses. Simulation results illustrate that O₃ formation was between VOCs-limited and transition regime. Xylenes and light alkenes were found to be key species in O₃ formation according to RIR values, and their sources were determined using the Positive Matrix Factorization (PMF) model. Paints and solvent use was the largest contributor to xylenes (54%), while petrochemical industry was the most important source to propene (82%). Discussions on VOCs and NO_X reduction schemes suggest that the 5% O₃ control goal can be achieved by reducing VOCs by 20%. To obtain 10% O₃ control goal, VOCs need to be reduced by 30% with VOCs/NO_X larger than 3:1.     

精神活性物质在北京市某污水处理厂中的污染特征与生态风险

为了解污水处理厂对精神活性物质的去除特征及总出水对受纳水体的生态风险,采用固相萃取-高效液相色谱-串联质谱法调查了北京市某污水处理厂中13种精神活性物质的浓度水平与负荷量变化,并运用RQ（risk quotient,风险熵）对总出水中精神活性物质进行风险评估.结果表明:①13种精神活性物质在总进水与总出水中均能检出,总质量浓度平均值分别为2 395.10和63.59 ng/L,其中ρ（EPH）（EPH表示麻黄碱）占比分别为93.9%和67.9%,其次为COD（可待因）与METH（甲基苯丙胺）.污水处理厂上游地表水中ρ（EPH）、ρ（METH）与ρ（KET）（KET为氯胺酮）均高于总出水及其下游地表水,说明上游沿河可能有新的污染源输入.②污水处理厂对NK（去甲氯胺酮）、BE（苯甲酰爱康宁）和MTD（美沙酮）均呈负去除,其他精神活性物质的去除主要发生在二级生物处理与三级处理（超滤膜与UV消毒）阶段.③污水处理厂服务区域内精神活性物质的周内负荷量存在一定波动,AMP（苯丙胺）、METH、MDA（3,4-亚甲二氧基苯丙胺）、MDMA（3,4-亚甲二氧基甲基苯丙胺）、KET与HER（海洛因）的负荷量均在周末升高.④污水处理厂总出水中精神活性物质的生态风险均较低（RQ < 0.10）.研究显示,污水处理厂不能完全去除污水中的精神活性物质,总出水中残留精神活性物质对受纳河流生态系统产生的长期混合效应不容忽视.      

不同浓度锌处理下水稻幼苗对镉的累积效应

为探究锌（Zn）对水稻镉（Cd）累积的影响及其根表铁膜所发挥的作用,选取Cd高累积型水稻品种中9优547（简称"Z547"）和Cd低累积型水稻品种金优402（简称"J402"）,采用温室水培试验,研究0、2、5、10、15和20 μmol/L等6个Zn浓度下水稻幼苗对Cd的累积效应,以及不同浓度Zn处理对根表铁膜生成量的影响.结果表明:①随着c（Zn）的增加,Z547和J402水稻幼苗生物量均呈先增后减的趋势,分别在c（Zn）为2和10 μmol/L时达到最大值.②Z547和J402水稻幼苗中w（Cd）均呈先降后增的趋势,分别在c（Zn）为5和2 μmol/L时达到最小值;当水稻幼苗中w（Cd）达到最小值时,Z547根和地上部中w（Cd）分别为31.65和11.47 mg/kg,J402根和地上部中w（Cd）分别为22.58和14.36 mg/kg.③不同浓度Zn处理下水稻幼苗各部位中w（Cd）均与根表铁膜中w（Mn）、w（Fe）、w（Fe+Mn）呈显著正相关,高铁膜处理水稻幼苗中w（Cd）显著高于低铁膜处理,表明根表铁膜生成量的增加会促进Cd在水稻幼苗中的累积.研究显示,当c（Zn）较低时,c（Zn）的增加会抑制水稻幼苗对Cd的累积;当c（Zn）较高时,c（Zn）的增加会促进水稻幼苗对Cd的累积,而Zn可通过控制根表铁膜的生成来影响水稻幼苗对Cd的累积.