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应用平衡吸附法,研究了不同pH值、离子强度、类胡敏酸浓度和接触时间条件下,黑土、白浆土及蒙脱石对类胡敏酸(HLA)的吸附作用.结果表明:随着HLA浓度的增加,土壤及蒙脱石对HLA的吸附量增加.黑土、白浆土及蒙脱石对HLA的吸附等温线均为L型,其吸附不可逆性表现为白浆土>蒙脱石>黑土.通过Langmiur方程计算,蒙脱石、白浆土对HLA达到吸附平衡时的最大吸附量分别为764.7、790.3mg·g-1,而黑土为35.27mg·g-1.Freundlich方程可以很好地描述白浆土、蒙脱石对HLA的吸附和解吸等温线,而Temkin方程可以很好地描述黑土对HLA的吸附和解吸等温线.同时,3种材料的吸附自由能ΔG°<0,吸附热Qm>0,表明其对HLA的吸附是自发的、放热的过程.随着pH的升高,黑土、白浆土及蒙脱石对HLA的吸附量减少;随离子强度的增加,黑土、白浆土及蒙脱石对HLA的吸附量增大.黑土、白浆土及蒙脱石对HLA的吸附动力学过程划分为快反应和慢反应阶段,其中,蒙脱石、白浆土对HLA的吸附动力学过程用一级动力学方程拟合的效果最好,而对黑土而言,用Elovich方程描述更合适.
The adsorption of humic acid (HLA) on black soil, albic soil and montmorillonite under different conditions of pH value, ionic strength, humic acid concentration and contact time was studied by equilibrium adsorption method. The results showed that With the increase of HLA concentration, the adsorption amount of HLA to soil and montmorillonite increased, while the adsorption isotherms of HLA for black soil, white earth and montmorillonite were L type, and the adsorption irreversibility showed white soil> montmorillonite Stone> black soil.The maximum adsorption capacity of montmorillonite and white soil for adsorption equilibrium of HLA reached 764.7 and 790.3 mg · g-1, respectively, and 35.27 mg · g-1 for black soil calculated by Langmiur equation.The Freundlich equation can The isotherms of adsorption and desorption of HLA on white soil and montmorillonite are well described, and the Temkin equation can well describe the adsorption and desorption isotherms of HLA on black soil.At the same time, the adsorption free energy ΔG ° < 0, the adsorption heat Qm> 0, indicating that the adsorption of HLA is a spontaneous and exothermic process.With the increase of pH, the adsorption amount of HLA to black soil, albic soil and montmorillonite decreases; with the increase of ionic strength Increasing the adsorption of HLA on black soil, albic soil and montmorillonite increased the adsorption of HLA on black soil, albic soil and montmorillonite Mechanical processes are divided into fast reaction and slow reaction stages. Among them, montmorillonite and albicosol have the best fitting effect on HLA adsorption kinetics with the first-order kinetic equation. For black soil, Elovich equation more suitable.