溶液环境对纳米Fe_2O_3/水界面NOM吸附过程中疏水效应的影响

Influence of solution environment on hydrophobic effect in process of NOM adsorption at nano-Fe_2O_3/water interface

以腐殖酸和纳米Fe2O3为对象,着重研究了腐殖酸分子在纳米Fe2O3表面的吸附过程中的疏水效应,借助红外光谱和热重等分析方法研究了腐殖酸吸附前后的疏水性随溶液环境变化的规律。结果表明,当离子强度为0、0.005、0.01和0.05 mol/kg,pH从7变到12时,纳米Fe2O3吸附溶解性腐殖酸分子后形成的复合体的热失重量随着pH的升高先减小后增大。当pH从7升高到10时,亲水性降低,疏水性增强;当pH从10升高到12时,亲水性增强,疏水性降低。当离子强度为0.001 mol/kg,pH从7变到12时,复合体的热失重量随着pH的升高而减小,亲水性降低,疏水性增强。当pH为定值,离子强度变化时,纳米Fe2O3吸附溶解性腐殖酸分子后形成的复合体的热失重量随着离子强度的增加不断变化,曲线呈现出波动趋势,亲、疏水性在交替变化。红外光谱分析结果说明,对纳米Fe2O3吸附溶解性腐殖酸分子后形成的复合体的亲疏水性起主要影响的官能团可能是亲水性的羟基—OH、羰基CO和疏水性的CH2烷烃。

Regarding the interaction between humic acid and Fe2O3 nanoparticles,the hydrophobic effect and the law about how the hydrophobic changes with the solution environment in the process of the humic acid＇s adsorption are discussed with infrared spectroscopy and thermo-gravimetric analysis methods.The results shows that,when the ionic strength is 0,0.005,0.01 and 0.05 mol/kg and pH value changes from 7~12,the thermal weight loss of the complex decreases initially and then increases during adsorption.Meanwhile,the hydrophilic capacity reduces and hydrophobic enhances when the pH increases from 7~10,and shows opposite trends completely when the pH changes from 10~12.When the ionic strength is 0.001 mol/kg,and pH value changes from 7~12,the thermal weight loss of the complex decreases,which means the hydrophilic reduces and hydrophobic enhances.When the pH value is constant and the intensity of ionic changes,the thermal weight loss of the complex keeps changing and the hydrophilic and hydrophobic change alternately.The infrared spectroscopy results indicate that hydrophilic hydroxyl—OH,carbonyl CO and the hydrophobic alkane CH2 may play a major role in the hydrophilic and hydrophobic of the HA-Fe2O3 complex.