【摘要】 为客观地评价乙醇汽油组分在环境中的迁移规律,并为其环境风险评估提供科学依据。通过静态吸附批量实验,研究了汽油组分甲苯在腐植酸上的吸附行为及乙醇对其的影响。结果表明,随着乙醇体积分数(fc)的增加,甲苯的溶解度呈线性增加。腐植酸对甲苯的吸附过程为快速吸附缓慢平衡,其吸附等温线均很好地符合Freundlich吸附模式。其中溶剂中乙醇的体积分数对甲苯在腐植酸上的吸附行为影响显著,在pH为(5.9±0.2),温度为(25±1)℃的情况下,随着溶剂中乙醇体积分数从0增加到20%,甲苯在腐植酸上的吸附系数(K)从(0.143±0.021)降至(0.066±0.012)mgn+1·L-n·g-1,并且吸附参数(1/n)有接近1的趋势,表明乙醇不仅能降低腐植酸吸附甲苯的能力,而且能够使腐植酸表面变得更加均质,从而使其吸附甲苯的等温吸附线线性增加。最后,通过拟合数据可得出,在实验条件下通过吸附数据计算出来乙醇的共溶剂效力值3.45,小于通过溶解数据计算出来乙醇的共溶剂效力值3.87,表明在乙醇影响下腐植酸可能会发生一定的溶胀。更多还原

【Abstract】 In order to accurately assess the migration of ethanol gasoline components in the environment and their environmental risks,batch experiments were carried out to investigate the sorption of toluene on humic acid with the presence of various content of ethanol.The results showed that as the volume fraction of ethanol increased,the solubility of toluene in system increased linearly.The sorption process could be divided into two stages,i.e.,fast sorption in the beginning and then slow sorption to the equilibrium.The sorption procedure of toluene on humic acid can be well described by the Freundlich model.The influence of presence of ethanol on sorption of toluene on humic acid was significant.Under the conditions of pH=5.9±0.2 and(25±1)℃,when ethanol fraction(in volume)increased from 0 to 20%,the sorption affinity(K)of toluene by humic acid decreased from(0.143±0.021)to(0.066±0.012)mg n+1 ·L-n ·g-1,and the Freundlich constan(t1/n)tended to be unity.This situation showed that ethanol could not only reduce sorption amount of toluene on humic acid,but also enhance the sorption homogeneity with increase in isotherm linearity.The fitted cosolvency power of ethanol was 3.45 from sorption data and it was less than that from solubility data,which was 3.87,under current experimental condition.This indicated that humic acid maybe swelled under the effect of ethanol.更多还原