【作者】 朱门君；

【导师】 葛飞；

【作者基本信息】 湘潭大学 ， 环境工程， 2010， 硕士

【摘要】 季铵盐阳离子表面活性剂广泛用作乳化剂、织物软化剂、消毒剂、杀虫剂、腐蚀抑制剂和个人护理产品,使用后作为工业、农业和生活废水排放进入环境中。作为是一类毒性较大的有机污染物,季铵盐阳离子表面活性剂对水生生态系统的影响已引起国内外学者的广泛关注。论文在评述季铵盐阳离子表面活性剂生态毒性效应研究进展的基础上,以环境敏感生物-单细胞绿藻普通小球藻为水生生物代表,研究了季铵盐阳离子表面活性剂对小球藻的急性毒性及其定量结构-活性关系（QSAR）。论文取得了以下一些有价值的研究结果:1、季铵盐阳离子表面活性剂对小球藻有较强的抑制作用。在实验条件下,随着季铵盐阳离子表面活性剂浓度的增加,其对小球藻的抑制作用增强。通过概率单位法计算得出C₈TMAB、C₁₀TMAB、DTAB、TTAB、CTAB、STAB、CTAC、BDDAC、BDTAC、BDHAC、EDDAB、EDHAB和CPB等13种季铵盐阳离子表面活性剂对小球藻的96 h-EC₅₀分别为9.472、1.138、0.188、0.182、0.156、0.108、0.137、0.203、0.174、0.161、0.197、0.121和0.132 mg/L,毒性的大小表现为以下规律:取代基相同、烷基链长度不同的季铵盐阳离子表面活性剂随着烷基链长度增加,毒性增大;取代基对烷基链长度相同的季铵盐阳离子表面活性剂的毒性影响较小;烷基链长度CL=8¹0的季铵盐阳离子表面活性剂的96 h-EC₅₀在1¹0 mg/L之间,对小球藻分别属于高毒性化合物;烷基链长度CL=12¹8的季铵盐阳离子表面活性剂的96 h-EC₅₀均在1 mg/L以下,对小球藻属于极高毒性化合物;季铵盐阳离子表面活性剂的log(1/EC₅₀)值与辛醇/水分配系数logKow和烷基链长度CL存在抛物线关系,调整相关系数R²adj>0.93。2、应用Gaussian 03程序的密度泛函理论（DFT）方法在B3LYP/6-31G（d）水平上计算了11种季铵盐阳离子表面活性剂的29个理化量化参数,采用Simca统计软件的偏最小二乘（PLS）回归分析方法,对活性参数log(1/EC₅₀)进行了定量结构-活性关系（QSAR）的研究。最优模型的3个PLS主成分解释了自变量累计方差的95.3%和因变量累计方差的92.8%,具有良好的相关性、稳健性和内部预测性。模型分析表明:季铵盐阳离子表面活性剂的分子体积越大,log(1/EC⁵⁰)值越大;烷基链长度CL、极化率张量α_zz、分子中氢原子所带最大正电荷qH⁺和熵S^?是影响季铵盐阳离子表面活性剂毒性的主要因素;log(1/EC⁵⁰)值随分子的CL、α_zz和S^?的增大而增大,随qH⁺的增大而减小。3、简谐振动频率和自然键轨道分析显示,X-N键长和分子中氢原子所带最大正电荷qH⁺越小,烷基链长度相同季铵盐阳离子表面活性剂对小球藻的毒性表现出增大的趋势;在NBO分析中,稳定能E2主要由X^–的孤对电子和C–H键的BD^*轨道的相互作用产生,且CTAB的稳定能大于CTAC。更多还原

【Abstract】 Quaternary ammonium compounds （QACs）, which is widely used as emulsifiers, fabric softeners, disinfectants, pesticides, corrosion inhibitors and personal care products, have stayed in the wastewater generated from industry, agriculture and municipality. As a kind of organic pollutants with high toxicity, the ecotoxicity of QACs on aqueous ecosystems has drawn much attention.Based on the research progress of the ecotoxicity of QACs, this paper investigated the acute toxicity of QACs on Chlorella vulgaris, a single-celled green alga which is sensitive to environment, and its quantitative structure-activity relationship （QSAR）. The results could be listed as follows:1. A strong inhibition resulted from QACs was observed on growth of Chlorella vulgaris. The higher the concentration of the QACs, the stronger the growth of Chlorella vulgaris was restrained. After 96 h, EC50 of 13 QACs including C8TMAB, C10TMAB、DTAB, TTAB, CTAB, STAB, CTAC, BDDAC, BDTAC, BDHAC, EDDAB, EDHAB and CPB on C. vulgaris was calculated by the probit method as 9.472, 1.138, 0.188, 0.182, 0.156, 0.108, 0.137, 0.203, 0.174, 0.161, 0.197, 0.121 and 0.132 mg/L, respectively. The results showed that the toxicity of QACs with the same substituent groups was increased with the increase of alkyl chain length, while QACs with different substituent groups performed similar toxicity. QACs with alkyl chain length of from 12 to 18, was expected as strong poison to Chlorella vulgaris with 96 h-EC50 lower than 1.0 mg/L; And QACs with alkyl chain length of from 8 to 10 was classified as high poison to Chlorella vulgaris with 96 h-EC50 in 1.0-10 mg/L. A parabola relationship was performed between log（1/EC50） of the surfactant and octyl alcohol/water partition coefficient, logKow, or the alkyl chain length CL and the R2adj was larger than 0.93.2. Density function theory （DFT） of Gaussuan 03 program was employed under the level of B3LYP/6-31G（d） to calculate 29 physico-chemistry and quantum chemistry parameters of 11 QACs, and investigation on QSAR toward log（1/EC50） was conducted by partial least squares （PLS） regression of Simca software. The optimal PLS model with the cumulative cross-validated regression coefficient （Q2cum = 0:893） and the correlation coefficient between observed values and fitted values （R = 0.975） explained 95.3% of the variance of the independent variables and 92.8% of the variance of the dependent variable, indicating good goodness-of-fit, robustness and internal predictivity. The results showed that the larger the molecule volume of QACs, the higher the log(1/EC₅₀), and the toxicity of QACs was greatly affected by factors including CL,α_zz, S^? and qH⁺, which could be concluded as that it was enhanced with longer CL, strongerα_zz and larger So, but decreased with an increasing qH⁺.3. Harmonic vibration frequencies and natural bond orbital analysis showed the toxicity of QACs with the same alkyl chain length on C. vulgaris enhanced with the decrease of X-N bond lengths and the most positive net atomic charges on a hydrogen atom qH⁺. The stabilization E2 could be mainly by the interaction of the alone electron pair of X- and BD* orbit on C-H bond, and the stabilization of CTAB can be greater than CTAC.更多还原