白浆土对腐殖酸的吸附等温线和动力学研究

白浆土是吉林省和黑龙江省东部地区的主要农田土壤之一,研究白浆土对腐殖酸的吸附作用,可为探究白浆土的固碳潜力提供理论依据。采用批量平衡法,分析不同有机碳含量的白浆土及其组分(包括去有机质土壤、粉粒、黏粒)对腐殖酸的吸附动力学和等温吸附特性。结果表明:随吸附时间的延长,白浆土及其各组分对腐殖酸的吸附量逐渐增加;整个吸附动力学过程可划分为快速(0～30 min)和慢速(30～480 min)反应阶段,伪二级动力学方程的拟合效果优于Elovich、双常数和伪一级动力学方程。白浆土及其各组分对腐殖酸的吸附量随腐殖酸初始浓度的增加逐渐增大,Langmuir方程的拟合效果通常优于Freundlich方程和Temkin方程。随白浆土有机碳含量的增加,其对腐殖酸的最大吸附量分别为26.9,24.1,15.6 mg/g。而白浆土不同组分相比,最大吸附量的顺序依次为黏粒>去有机质土壤>粉粒,黏粒对腐殖酸的吸附量分别是原土的2.15～3.88倍,去有机质土壤的1.61～2.21倍,粉粒土壤的7.90～8.65倍。有机碳含量低的白浆土对腐殖酸具有更强的吸附能力,黏粒含量高的白浆土对腐殖酸的吸附潜力更大。

Adsorption Isotherm and Kinetics of Humic Acid in Albic Soil

Albic soil is one of the main farmland soils in the eastern part of Jilin Province and Heilongjiang Province. Studying the adsorption of humic acid by albic soil can provide a theoretical basis for exploring the carbon sequestration potential of albic soil. Batch balance method was applied to analyze the adsorption kinetics and isothermal adsorption characteristics of albic soil with different organic carbon content and its components (including de-organic soil, silt, clay) to humic acid. The results showed that with the prolongation of adsorption time, the amounts of humic acid adsorbed by albic soil and its components increased gradually; the whole adsorption kinetics process could be divided into fast reaction (0~30 min) and slow reaction (30~480 min) stage. At the reaction stage, the fitting effect of the pseudo second-order kinetic equation was better than that of Elovich, double constant and pseudo first-order kinetic equation. The amount of humic acid adsorbed by albic soil and its components increased with the increasing of the initial concentration of humic acid, and the fitting effect of the Langmuir equation was usually better than that of the Freundlich equation and the Temkin equation. With the increasing of organic carbon content of albic soil, the maximum adsorption amounts for humic acid were 26.9, 24.1 and 15.6 mg/g, respectively. For the different components of the albic soil, the maximum adsorption amount followed the order of clay > de-organic soil > powder, and the adsorption amount of clay was 2.15 to 3.88 times that of the original soil, 1.61 to 2.21 times that of the deorganic soil, 7.90 to 8.65 times that of the powder soil. The above results showed that the albic soil with low organic carbon content had stronger adsorption capacity to humic acid, and the albic soil with high clay content had greater adsorption potential to humic acid.