Y型与ZSM-5型分子筛吸附VOCs性能的对比

从疏水性较好的分子筛中筛选出2类吸附性能优良的分子筛,通过实验考察其对VOCs的吸附量、脱附量、吸附穿透曲线、脱附活化能等,评价其对VOCs的吸附脱附性能;评估了所选分子筛经多次吸附再生后的性能稳定性,建立了一套分子筛工业应用性能指标体系。结果表明：Y型分子筛性能优于ZSM-5型分子筛;同种分子筛比表面积及孔径越大,单位质量能吸附的VOCs量越多;在甲苯/乙酸丁酯的竞争吸附体系中,Y型分子筛及ZSM-5型对甲苯的吸附量较单组分情况下分别下降了50.1%、40.1%,而对乙酸丁酯的吸附量分别增加了189%、102%;甲苯在Y型分子筛上的脱附活化能为76.7 kJ·mol⁻¹,在ZSM-5分子筛上的脱附活化能为64.7 kJ·mol⁻¹;Y型分子筛和ZSM-5型分子筛均具有较好的循环使用性,吸附性能稳定;Yoon-Nelson模型能较好地拟合分子筛吸附穿透曲线,拟合系数在0.97以上。     

交通空气污染对大鼠子代发育及社交行为的影响

交通空气污染与儿童自闭症的关联时有报道,但其因果关系仍待进一步探索。为研究出生前后暴露于不同水平的交通空气污染环境对生长发育和自闭症相关社交行为的影响,将Wistar大鼠雌雄1∶1交配,受孕雌鼠根据子代接触交通污染的时间(出生后暴露或胚胎期暴露)及浓度(低、中和高3个水平)分为6组。在子代出生后21～27 d,测量子代的体重、身长及大脑脏器系数,并根据三箱实验评估社交行为,同时检测仔鼠脑组织组蛋白H3第4个赖氨酸(H3K4)的甲基化水平。结果显示,出生前后,尤其是胚胎发育阶段接触较高浓度的交通空气污染物可导致幼鼠体重及大脑湿重较低,身长较短、大脑脏器系数偏高等生长发育特征改变。同时,出生前后较高浓度的交通空气污染物暴露可导致幼鼠出现社交能力下降、社交记忆受损及社交新颖性减弱等典型自闭症样行为改变。虽然组蛋白H3K4甲基化水平与交通空气污染物浓度之间未见统计学关联,但出生后暴露组具有较高的H3K4甲基化水平,提示出生前后接触交通空气污染物可能与自闭症的发生发展有关,而不同暴露时期对脑组织H3K4甲基化水平的影响,为今后进一步探讨自闭症的表观遗传机制提供了线索。     

基于GIS的地质灾害风险预警系统设计

利用GIS软件的二次开发技术,应用基于风险评价的预警方法建立地质灾害预警模型,设计地质灾害风险预警系统,在Visual Studio 2012.NET的开发环境下,以C#作为开发语言,并结合ArcGIS Engine研发.最后以通化县作为研究区域,验证此系统的可行性,结果表明该系统实现了地质灾害风险预警预报,具有较高的...     

双频超声波预处理破解污泥的研究

通过正交试验选取双频超声波预处理破解污泥的最优条件。对于指标VSS/SS,最优的超声波预处理参数组合:双频组合18 kHz、20 kHz,声能密度0.075 W/mL,超声间隔时间5 s,影响显著顺序为双频组合>声能密度>超声间隔时间;对于指标NH3-N,最优的超声波预处理参数组合是:双频组合18 kHz、20 kHz,声能密度0.1 W/mL,超声间隔时间5 s,影响显著顺序为双频组合>声能密度>超声间隔时间。通过对比试验的方式进一步验证了双频超声波预处理破解污泥的效果,结果表明双低频组合更有利于提高污泥的沉降性能。     

Human health risk assessment of groundwater nitrate at a two geomorphic units transition zone in northern China

To assess groundwater nitrate contamination and its human health risks, 489 unconfined groundwater samples were collected and analyzed from Zhangjiakou, northern China. The spatial distribution of principle hydrogeochemical results showed that the average concentrations of ions in descend order was HCO₃^?, SO₄^2?, Na⁺, Ca²⁺, Cl^?, NO₃^?, Mg²⁺ and K⁺, among which the NO₃^? concentrations were between 0.25 and 536.73 mg/L with an average of 29.72 mg/L. In total, 167 out of 489 samples (~ 34%) exceeded the recommended concentration of 20 mg/L in Quality Standard for Groundwater of China. The high NO₃^? concentration groundwater mainly located in the northern part and near the boundary of the two geomorphic units. As revealed by statistical analysis, the groundwater chemistry was more significantly affected by anthropogenic sources than by the geogenic sources. Moreover, human health risks of groundwater nitrate through oral and dermal exposure pathways were assessed by model, the results showed that about 60%, 50%, 32% and 26% of the area exceeded the acceptable level (total health index>1) for infants, children, adult males and females, respectively. The health risks for different groups of people varied significantly, ranked: infants> children> adult males>adult females, suggesting that younger people are more susceptible to nitrate contamination, while females are more resistant to nitrate contamination than males. To ensure the drinking water safety in Zhangjiakou and its downstream areas, proper management and treatment of groundwater will be necessary to avoid the health risks associated with nitrate contamination.     

基于FTA和ISM的氯化反应失控火灾爆炸危险性分析

为加强甲烷热氯化工艺过程的安全管理,对氯化反应过程进行危险性分析。本研究介绍了氯甲烷的危害特性以及反应釜失控造成火灾爆炸的危险性,借助事故树分析法中结构重要度的排序获取基本原因事件,在此基础上运用解释结构模型(ISM)对氯化反应过程进行火灾爆炸危险性分析,根据所得基本原因事件的层级划分可得到造成事故发生的直接、间接以及根本原因,最终由ISM分析结果提出针对甲烷热氯化工艺火灾爆炸事故的安全对策措施。     

Air pollution and body burden of persistent organic pollutants at an electronic waste recycling area of China

Environmental Geochemistry and Health - This paper reviews the concentrations of persistent organic pollutants (POPs) in atmosphere of an electronic waste (e-waste) recycling town, Guiyu, in...     

Dielectric barrier discharge plasma-assisted modification of g-C3N4/Ag2O/TiO2-NRs composite enhanced photoelectrocatalytic activity

Dielectric barrier discharge (DBD) plasma applied as surface treatment technology was employed for the modification of Ag₂O and graphitic carbon nitride (g-C₃N₄) powders. Subsequently, the pretreated powders were sequentially loaded onto TiO₂ nanorods (TiO₂-NRs) via electro-deposition, followed by calcination at N₂ atmosphere. The results indicated that at the optimal plasma discharge time of 5 min for modification of g-C₃N₄ and Ag₂O, photocurrent density of ternary composite was 6 times to bare TiO₂-NRs under UV-visible light irradiation. Phenol was degraded by using DBD plasma-modified g-C₃N₄/Ag₂O/TiO₂-NRs electrode to analyze the photoelectrocatalytic performance. The removal rate of phenol for g-C₃N₄-5/Ag₂O-5/TiO₂-NRs electrode was about 3.07 times to that for TiO₂-NRs electrode. During active species scavengers’ analysis, superoxide radicals and hydroxyl radicals were the main oxidation active species for pollutants degradation. A possible electron-hole separation and transfer mechanism of ternary composite with high photoelectrocatalytic performance was proposed.