作为一种典型的污染物,N,N-二甲基甲酰胺(N,N-dimethylformamide,DMF)具有排放量大、生态毒性高、难以降解的特性,但目前国内外尚缺乏相关基准标准研究。基于ECOTOX、Web of Science及中国知网等相关中英文文献和毒理数据库,收集并筛选...作为一种典型的污染物,N,N-二甲基甲酰胺(N,N-dimethylformamide,DMF)具有排放量大、生态毒性高、难以降解的特性,但目前国内外尚缺乏相关基准标准研究。基于ECOTOX、Web of Science及中国知网等相关中英文文献和毒理数据库,收集并筛选获得222条DMF对中国淡水生物毒性的文献数据,同时补充了DMF对麦穗鱼、黄颡鱼、河蚬、苏式尾鳃蚓、泥鳅、萼花臂尾轮虫、角突臂尾轮虫、莱茵衣藻共8种本土代表性物种的急性、慢性毒性测试数据,用于DMF的淡水生物水质基准推导。DMF水质基准共涉及26种淡水水生生物,涵盖了3个营养级,同时包含了草鱼、鳙鱼等在我国广泛分布的经济物种。其中急性数据涵盖7门15科24个物种,最敏感的物种为柱孢鱼腥藻和多变鱼腥藻;慢性毒性数据涵盖6门10科12个物种,最敏感的物种为模糊网纹溞。采用物种敏感度分布法(SSD)和毒性百分数排序法(TPR)分别计算我国淡水水生生物的DMF水质基准,其中SSD推导出短期水质基准为824.12 mg/L,长期水质基准为14.53 mg/L,TPR推导出短期水质基准为1 081.58 mg/L,长期水质基准为22.48 mg/L,建议采用SSD所推导基准作为DMF的水质标准。展开更多
Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterize d using IR,UV,TG-DTA,pH potential ti tration techniques￡(r)The molecular f ormulae of these compounds are pro-po...Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterize d using IR,UV,TG-DTA,pH potential ti tration techniques￡(r)The molecular f ormulae of these compounds are pro-posed to be HxMyAsMO10V2O40·zH2 O￡¨x￡1/21?￡3￡?y￡1/2￡±￡?￡2￡?M￡1/2Cr￡?Mn￡?Fe￡?Co￡?Ni￡?Cu￡?Zn￡(c)￡(r)They are all keggin structure￡(r)Surface nature of these compounds have been investigated by temperature programmed desorption and temperature programmed reducti on techniques￡(r)NH 3 -TPD results show that in TPD profile s of the compounds there are two desorption peaks corre sponding to weak acid sites of desorp tion,respectively￡(r)Desorbing activativon energy and preexponential factor of weak acid site of desorption for comp ounds have been calculated￡(r)H2 -TPR re-sults show that introducting transtion metal to molybdovanarsenic acid,the reduction peak temperatures of H2 -TPR shift regularly with increasing d electron numbers of transition metals￡(r)In addition,Zn and Cu heteropoly com-pounds have yet apparent effect of hydrogen spill over￡(r)展开更多
Pt Sn/MgAl 2O 4 catalysts prepared by co impregnation with nominal 0 35% platinum and varying content of tin (0～2 5%) were characterized by temperature programmed reduction (TPR) and temperature programmed desorption...Pt Sn/MgAl 2O 4 catalysts prepared by co impregnation with nominal 0 35% platinum and varying content of tin (0～2 5%) were characterized by temperature programmed reduction (TPR) and temperature programmed desorption of hydrogen (H 2 TPD). TPR results showed that platinum catalyzed the reduction of tin. However, the average oxidation state of tin after reduction depended upon the concentration of tin on the catalysts. H 2 TPD data indicated that tin addition inhibited the inactivated adsorption of hydrogen but promoted the activated adsorption, implying that tin modified both the ensembles of platinum and metal support interface, thus increasing hydrogen mobility and promoting hydrogen spillover.展开更多
文摘Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterize d using IR,UV,TG-DTA,pH potential ti tration techniques￡(r)The molecular f ormulae of these compounds are pro-posed to be HxMyAsMO10V2O40·zH2 O￡¨x￡1/21?￡3￡?y￡1/2￡±￡?￡2￡?M￡1/2Cr￡?Mn￡?Fe￡?Co￡?Ni￡?Cu￡?Zn￡(c)￡(r)They are all keggin structure￡(r)Surface nature of these compounds have been investigated by temperature programmed desorption and temperature programmed reducti on techniques￡(r)NH 3 -TPD results show that in TPD profile s of the compounds there are two desorption peaks corre sponding to weak acid sites of desorp tion,respectively￡(r)Desorbing activativon energy and preexponential factor of weak acid site of desorption for comp ounds have been calculated￡(r)H2 -TPR re-sults show that introducting transtion metal to molybdovanarsenic acid,the reduction peak temperatures of H2 -TPR shift regularly with increasing d electron numbers of transition metals￡(r)In addition,Zn and Cu heteropoly com-pounds have yet apparent effect of hydrogen spill over￡(r)
文摘Pt Sn/MgAl 2O 4 catalysts prepared by co impregnation with nominal 0 35% platinum and varying content of tin (0～2 5%) were characterized by temperature programmed reduction (TPR) and temperature programmed desorption of hydrogen (H 2 TPD). TPR results showed that platinum catalyzed the reduction of tin. However, the average oxidation state of tin after reduction depended upon the concentration of tin on the catalysts. H 2 TPD data indicated that tin addition inhibited the inactivated adsorption of hydrogen but promoted the activated adsorption, implying that tin modified both the ensembles of platinum and metal support interface, thus increasing hydrogen mobility and promoting hydrogen spillover.
