芘在土壤中的吸附和解吸行为研究

Sorption/Desorption Behavior of Pyrene in Soils

研究了芘在6种有机质和黏粒含量不同的土壤中吸附和解吸行为。结果表明,各土壤对芘的吸附速率很快,2d即可达到稳态,而芘的解吸速率却很缓慢,出现了解吸滞后现象。Freund lich方程能够很好的拟合6种土壤的吸附等温线,芘在土壤中的吸附自由能变化量为7.02~14.43 kJ.mol-1,表明芘在土壤中的吸附以物理吸附为主。芘在土壤中的吸附常数在0.059~30.966之间,当土壤有机质含量高于1%时,吸附常数与土壤有机质含量成正比,而解吸速率与有机质含量成反比,解吸进行30 d,只有9.84%~54.59%吸附的芘从土壤中解吸;有机质含量低于1%时,黏粒和有机质含量都对土壤的吸附/解吸能力有重要影响。

Sorption/desorption behavior of pyrene in six types of soils with different organic matter and clay contents was investigated in this paper.The results showed that sorption rate of pyrene onto these soils was rapid and reached constant after 2 days.However,pyrene desorption from the soils was relatively slow with a delay.The sorption isotherms of different soils were fitted to the Freundlich equation well.Free energy of sorption ranged from 7.02 to 14.43 kJ·mol^(-1),which indicated the spontaneity of the given sorption process of pyrene in soils.The sorption constants of these soils were in the range of 0.059~30.966.When the content of soil organic matter(SOM) was above 1%,the sorption constants were positively related to the contents of SOM and desorption rate was negatively related to the contents of SOM.9.84%~54.59% of pyrene sorbed in soils desorbed into water phase after 30 days.While with SOM content below 1%,clay mineral played an important role in pyrene sorption and desorption process.