对硝基氯苯在土壤和腐殖酸上的长期吸附与多步解吸的研究

采用批量平衡实验法研究了对硝基氯苯（p-NCB）在土壤和腐殖酸上的长期吸附和多步解吸，比较了连续的多步解吸与一步解吸的差异。结果表明，随着吸附时间的增加吸附量均会有所增加，随吸附时间增加吸附等温线的非线性增强。p-NCB在液相和固相上的初始浓度对吸附速率有一定影响，低浓度比高浓度时达到平衡的速率要低。对于两种受试土壤，两次解吸得到的等温线均无法与吸附等温线重合，表现出很强的吸附不可逆性。而尽管p-NCB在腐殖酸上表现出明显的非线性吸附（n = 0.794），但4次解吸后所得到的平衡位点与吸附所得的平衡位点基本落在同一条直线上，对数坐标下进行线性拟合的相关系数（R2）可达0.988，说明吸附过程是完全可逆的。

Long term sorption and multistep desorption of p-nitrochlorobenzene on soils and humic acids

Long-term sorption and multi-step desorption of p-Nitrochlorobenzene (p-NCB) on two soils and humic acids were studied by using bath equilibrium methods. The results showed that both sorption amount and nonlinearity of isotherm were time-dependent, which were increased as the sorption time prolonged. Initial aqueous concentration had great effect on the sorption rate of p-NCB. It needed more time to reach sorption equilibrium for the lower concentration samples than for the higher ones. For the two soils tested, both the one- and two-steps desorption isotherms could not overlap with the sorption isotherms, indicating the strong sorption hysteresis of p-NCB on the two soils. As concerned with humic acids, although the sorption of p-NCB on them presented a nonlinear characteristic (n=0.794), the one- to four-steps desorption isotherms were almost overlapped with the sorption isotherms. All the sorption and sequential four-steps desorption data fell on almost a same line, with a correlation coefficient (R2) of 0.988 by logarithmic scale linear regression, which indicated that the sorption of p-NCB on humic acids was almost completely reversible.