五氯酚在酸性土壤表面的吸附—解吸特征研究

ADSORPTIONDESORPTION OF PCP IN ACIDIC SOILS

本实验研究五氯酚在江西红壤和南京黄棕壤表面的吸附-解吸特征,结果表明:Freundlich和Langmuir等温吸附方程均能较好地描述PCP在两种土壤表面的吸附,且黄棕壤表面的最大吸附量大于红壤.用动力学方程对PCP在红壤中的吸附过程进行拟合,Elovich方程、双常数方程和一级动力学方程均得到较好的结果,其相关系数(R2)在0.96～0.99之间,达到极显著水平.Elovich方程反映出PCP在土壤表面吸附的能量非均质分布;而抛物线扩散方程不能描述PCP的吸附过程,其相关系数0.46～0.48.PCP在土壤中的解吸率与有机质含量和pH值相关,随有机质含量增加,PCP解吸率降低,即黄棕壤表土＜黄棕壤底土,红壤表土＜红壤底土;随模拟酸雨的pH值降低,土壤因对PCP的吸附能力增加,其解吸率降低.

Characteristics of adsorptiondesorption of PCP were investigated in red soils and yellow-brown soils. The results showed that isotherm adsorption of PCP was best described by Freundlich and Langmuir equations and the maximal PCP adsorption occurred in yellow brown soils rather than in red soils. Kinetics of PCP adsorption could be fitted by Elovich equation and dual constant equation and first order equation, of which the correlation coefficient (R2) ranged between 0.96~0.99 and reached a significant level. Data fitted by Elovich equation indicated energy distributions of PCP adsorption onto the soil surface were nonhomogeneous. Parabolic diffusion equation could not describ the adsorption process of PCP with R2 ranging between 0.46~0.48. Desorption rate of PCP in acidic soils was closely related to contents of Organic Materials (OM) and pH in solution and could be reduced with the increase in OM and the decrease in pH value of the simulated acid rain.