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为了探讨ATZ(阿特拉津)在黄土中的吸附/解吸行为及主要影响因素,以我国西北黄土为供试土样,采用批量试验法研究了黄土对ATZ的吸附动力学和热力学行为特征.结果表明:黄土对ATZ的吸附动力学过程更符合准二级动力学模型,吸附热力学过程更符合线性分配的Henry吸附模型(R2>0.90),吸附过程中ΔGθ(吉布斯自由能)及ΔHθ(焓变)均小于0、ΔSθ(熵变)大于0,25~45℃温度范围内E(吸附平均自由能)为0.86~1.30 k J/mol,表明黄土对ATZ的吸附过程以物理吸附为主,属于自发放热过程且导致吸附体系混乱度增加.黄土对ATZ的吸附影响因素分析结果显示,随着系统温度的升高,ATZ在黄土中的饱和吸附量下降;pH在2~10范围内变化时,ATZ在黄土中的饱和吸附量随pH的增加呈明显降低趋势;初始ρ(ATZ)从2.5 mg/L增至10.0 mg/L时,黄土对ATZ的饱和吸附量也相应地从0.082 5 mg/g增至0.621 0 mg/g.结果显示,ATZ在黄土中的吸附速率受内部扩散、表面吸附和液膜扩散的共同影响,并且吸附过程主要受到土壤有机质疏水性分配作用的影响.
In order to investigate the adsorption and desorption behavior of ATZ in loess and its main influencing factors, the adsorption kinetics and thermodynamic behavior of loess on ATZ were studied by batch test method using the loess in northwestern China as test soil sample. The results show that the adsorption kinetics of ATZ is more in accordance with quasi-second-order kinetics model, and the adsorption thermodynamic process is more in line with the Henry adsorption model (R2> 0.90), ΔGθ (Gibbs free energy) and ΔHθ (Enthalpy change) is less than 0, ΔSθ (entropy change) is greater than 0, E (adsorption freeradical energy) in the temperature range of 25 ~ 45 ℃ is 0.86-1.30 kJ / mol, indicating that adsorption of loess on ATZ by physical adsorption as The results showed that the adsorption capacity of ATZ in loess decreased with the increase of system temperature, and the adsorption capacity of ATZ in loess decreased with pH increasing from 2 to 10 At the same time, the saturated adsorption amount of ATZ in loess decreased with the increase of pH. When the initial concentration of ATZ increased from 2.5 mg / L to 10.0 mg / L, the saturated adsorption capacity of ATZ on loess increased 0.082 5 mg / g to 0.621 0 mg / g.The results showed that ATZ was in loess The adsorption rate is affected by internal diffusion, surface adsorption and liquid film diffusion, and the adsorption process is mainly affected by the hydrophobic distribution of soil organic matter.