DFT Study of Electron Affinities of o-, m-,p-Halobenzyl Radicals

The electron affinities of the isomer XC6H4CH2/ XC6H4CH2- (X=F, Cl, Br) species have been determined using seven density functional theory (DFT) methods. The basis set used in this work is of double-ζ plus polarization quality with additional diffuse s- and p-type functions, denoted DZP++. Three different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The most reliable adiabatic electron affinities are obtained at the DZP++ BPW91, BP86, and B3LYP level of theory. The BPW91 methods are the closest to the experiment values; The BHLYP method predicts the smallest EAad and B3P86 method predicts the largest EAad, which are the worst reliable methods. In addition, for a given halogen substituent, the meta isomer has the largest electron affinity and the para isomer has the smallest.     

过渡金属离子荧光探针——2,6-二氨基吡啶的研究

研究了2,6-二氨基吡啶(DAPD)与金属离子作用前后的荧光光谱和吸收光谱。结果表明,在加入过渡金属离子后,其发射光谱和吸收光谱产生红移,且光谱强度随金属离子浓度的加大而增强;但加入K+,Na+,Mg2+,Ca2+,Pd2+等金属离子后,DAPD无响应。根据Irving-Williams顺序,以过渡金属中络合能力较强的Cu2+为代表,考察了其对DAPD吸收光谱及荧光光谱的影响。Cu2+浓度在2.5×10-7～3.5×10-6mol/L范围内与荧光强度呈线性关系,求算出DAPD与Cu2+的结合比为2∶1。比     

普通化学实验教学改革的几点建议

普通化学是高等工科院校非化学专业的一门重要基础课,普通化学实验是普通化学的重要组成部分,针对普通化学实验教学中存在的问题,提出在教学过程中开设微型化学实验,并改革实验前预习检查的方式,实验过程中操作要求、实验完成后原始数据记录以及实验考核等环节,提高学生的学习兴趣,并要求理论课和实验课同人授课,以达到更好的教学效果。     

厌氧／好氧MBR处理印染废水中运行参数的优化研究

膜生物反应器是一种新型的污水处理设备,如何能让系统稳定高效的运行是现在面临的主要问题之一.因此,对系统的出水方式、DO、HRT以及膜的操作压力等参数进行了研究,结果表明,系统采用间歇式出水、DO为2.0～3.0 mg/L,HRT=9 h,曝气量2.8 m3/h,抽吸时间10 min,停吸时间8 min时处理效率最高.