【摘要】 通过批量平衡法,研究4个浓度(0、0.8、4、8 g/kg)尿素处理与吡虫啉混施对吡虫啉在粤西蔗区土壤(红壤)中吸附特性的影响,为今后尿素与吡虫啉混施在粤西蔗区的使用提供一定的理论依据。结果表明:(1)吡虫啉在土壤中的吸附于24 h达到平衡,吸附动力学过程符合准二级动力学方程和Elovich方程,吸附过程是先快后慢最终平衡。同时存在化学吸附和物理吸附,随尿素浓度(0.8、4、8 g/kg)升高,吡虫啉吸附量分别下降6.00%、13.52%和20.41%;(2)吸附过程同时满足Freundlich和Langmuir等温吸附模型,表明吸附过程同时存在单层吸附和多层吸附,Freundlich吸附常数随尿素浓度升高降低4.30%～31.41%,吸附能力下降;(3)随尿素浓度升高,吉布斯自由能ΔG<0,吸附是自发进行的物理吸附;熵变ΔS>0且逐渐升高,吸附过程混乱度逐渐升高;焓变ΔH<0且逐渐升高,吸附放热程度逐渐降低。表明:尿素可以降低吡虫啉在土壤中的吸附能力,尿素与吡虫啉混施不利于吡虫啉在土壤中的固定。更多还原

【Abstract】 In order to study the effects of urea and imidacloprid mixed application on the adsorption of imidacloprid in red soil, a batch equilibrium test method was used to analyze the adsorption kinetics, isothermal adsorption, and temperature effects of imidacloprid and imidacloprid with urea on adsorption. The results show that:(1) the adsorption of imidacloprid in red soil reaches equilibrium in 24 hours and conforms to the quasi-second-order kinetic equation and the Elovich equation, indicating that the adsorption process is fast first and then slow, and there are both chemical and physical adsorption, urea added that the adsorption capacity and adsorption rate of imidacloprid.With the increase of urea concentration(0.8, 4, 8 g/kg), the adsorption of imidacloprid decreased by 6.00%, 13.52%and 20.41%, respectively, compared with CK(0 g/kg urea);(2) the adsorption process simultaneously satisfies the Freundlich and Langmuir isothermal adsorption model, showing that there are both single-layer adsorption and multi-layer adsorption in the adsorption process, and Freundlich adsorption constant decreased by 4.30%-31.41%with the increase of urea concentration;(3) Gibbs free energy is less than 0 under different temperature conditions,indicating that adsorption occurs spontaneously. The entropy changes are all greater than 0, indicating that the degree of freedom in the adsorption process increases. Enthalpy changes is less than 0 and increases gradually, and the degree of adsorption exothermic decreases gradually. It is shown that urea can reduce the adsorption capacity of imidacloprid in soil, and the mixed application of urea and imidacloprid is not conducive to the fixation of imidacloprid in soil.更多还原