天然腐殖酸对柴油在寒旱区黄土上吸附特性的影响

选用西北寒旱区黄土为供试土样,通过热力学和动力学吸附试验研究了干旱区低有机质黄土对柴油的吸附行为,以及提取的天然腐殖酸对柴油在黄土上吸附行为的影响。结果表明,无论是否加入腐殖酸,柴油在黄土颗粒上的吸附都符合Freundlich方程,且腐殖酸质量浓度对柴油的吸附量有显著影响。在27℃时,加入10 mL质量浓度为40 mg/L的腐殖酸溶液后,柴油在黄土上的饱和吸附量由12.034mg/g减小为7.407 mg/g,且吸附量随温度的升高而降低,表明吸附为自发的放热过程。描述柴油在黄土上吸附动力学的最优方程为Elovich方程,其次为双常数方程。无论是否加入腐殖酸,黄土对柴油的吸附都在短时间内达到平衡。对吸附影响因素的分析结果表明,柴油在黄土上的吸附随溶液pH值的增大而降低;黄土颗粒粒径越小,柴油在土样上的吸附量越大。

Influence of the natural humic acid on the adsorption behavior of diesel oil on loess soil

The present study is aimed to disclose the influence of natural humic acid on the adsorption behavior of diesel oil on loess soil. For this purpose,we have conducted thermodynamics and dynamic experiments on the adsorption characteristics of diesel oil on northwest loess soil,particularly the influence of natural humic acid extracted from the loess soil on the adsorption of diesel oil.The said thermodynamics experiments were carried out at the temperatures of 27 ℃,37 ℃ and 47 ℃ in the presence or absence of natural humic acid,respectively while the dynamic experiments were conducted at 27 ℃ with and without humic acid.The results of our experiments show that the adsorption of diesel oil on the loess soil comes into close conformity with the Freundlich isothermal equation with no regard of humic acid.However,the presence of humic acid can significantly affect the adsorption capacity.Furthermore,we have found that the adsorption quantity of diesel oil on loess soil decreases from 12.034 mg/g to 7.407 mg/g at presence of 10 mL 40 mg/L humic acid at 27 ℃.The adsorption capacity of diesel oil has also been found to drop with the increase of environmental temperature.When the temperature increased from 27 ℃ to 47 ℃, the adsorption rate of diesel oil on loess soil would decrease from 12.034 mg/g to 4.228 mg/g,showing that the adsorption of diesel oil on loess soil was a spontaneous exothermic process.The adsorption kinetics of diesel was best in conformity with Elovich kinetics equation,and next was fit for double-constant equation.And,then,a quick adsorption balance would appear no matter with or without humic acid in the experiments,the balance state can last about 6 h.Based on the experiment mentioned above,we have also discussed the effects of pH value and soil particle size on the absorption of loess soil.The results suggest that the adsorption capacity of the diesel tends to decrease with the increase of the pH value in the solution.Besides,the adsorption quantity of the diesel turns to be higher at the smaller soil particles.That is to say,when the soil particle sizes increase,the adsorption rate of the diesel oil turns to be slower.