3种土壤对扑草净的吸附过程及其化学特征基团变化

Adsorption of Prometryn in 3 Types of Soil and the Changes of Their Chemical Characteristic Groups

为了解除草剂扑草净在土壤中的吸附过程,探讨其在土壤中迁移、转化以及生物利用的有效性,采用批量平衡法和傅里叶红外光谱法等手段,研究南方水稻土、红壤和黄壤对除草剂扑草净的吸附动力学特征以及吸附过程中主要基团的变化。结果表明:扑草净在3种供试土壤的吸附动力学过程经历了快速(180 min之间)、慢速(180 min之后)和平衡(720 min)吸附3个阶段,准二阶动力学方程与土壤对扑草净的吸附动力学过程拟合程度较高(R^(2)>0.94)。3种土壤的红外光谱图均在3621、1645 cm^(-1)和1028 cm^(-1)等处有特征吸收峰,表明图谱属于蒙脱石型图谱。扑草净在吸附前期(20 min)就吸附在土壤表面,且土壤黏土矿物和有机物对吸附过程作出积极贡献;较其他分子间作用力而言,氢键对整个吸附过程起着主导作用,羟基官能团在扑草净吸附过程中具有重要地位。

In order to understand the adsorption-desorption process of prometryn in soil and explore its migration,transformation and bioavailability in soil.In this study,batch balance method and Fourier infrared spectroscopy were used to study the adsorption kinetic characteristics of paddy soil,krasnozem and zheltozem and the changes of main groups during the adsorption process.The results showed that the adsorption kinetics of prometryn in the 3 soils tested underwent 3 stages of fast(between 180 min),slow(after 180 min)and equilibrium(720 min)adsorption.The quasi-second-order kinetic equation was consistent with the adsorption kinetics of prometryn in the soil(R^(2)>0.94).Infrared spectra of the 3 soils all showed characteristic absorption peaks of infrared spectra,such as 3621,1645 cm^(-1) and 1028 cm^(-1),belonging to the Montmorillonite pattern.In the early stage of adsorption(20 min),prometryn was adsorbed on the soil surface,and soil clay minerals and organic matter made positive contributions to the adsorption process.Compared with other intermolecular forces,hydrogen bonds play a dominant role in the whole adsorption process.Hydroxyl functional groups play an important role in the process of adsorption.