名山县蒙山茶园土壤各粒级组分对K^+吸附-解吸特征的影响

Effect of Soil Particle Size Fraction on Potassium Sorption-Desorption from Tea Garden Soil in Mengshan,Mingshan County

以名山县蒙山茶园紫色土为对象,用物理方法将蒙山茶园紫色土分成粒径大小不同的土壤组分(≤0.002mm,0.02～0.002mm,0.2～0.02mm,2～0.2mm),分别通过动力学和热力学方法研究它们对K+的吸附-解吸行为。结果表明:紫色土不同粒级组分对K+的吸附量表现为小于0.002mm>0.02～0.002mm>原土>0.2～0.02mm>2～0.2mm,而解吸量则呈相反的规律。用Elovich方程、双常数方程、抛物线扩散方程及一级扩散方程分别对K+的吸附-解吸动力学数据进行拟合,并用Langmuir、Freundlich和Temkin热力学方程对等温吸附过程进行拟合。原土及各粒级组分K+的吸附量均随K+初始浓度的增大而增大,但各粒级组分吸附量大小关系各不相同,K+均向最小粒径富集。运用动力学方法,原土和各粒径组分对K+的吸附特性均用Elovich吸附方程拟合最佳,原土和各粒级组分对K+的解吸特性均用Elovich解吸方程拟合效果最佳。运用热力学方法,原土和土壤各粒级组分以及分别去除有机质和游离氧化铁后对K+的吸附特性均用Freundlich吸附方程拟合效果最佳,原土和土壤各粒级组分以及分别去除有机质和游离氧化铁后对K+的解吸特性均用Freundlich吸附方程拟合效果最佳。

taking purple tea garden soil in Mengshan,Mingshan county,as studied object,dividing the Mengshan purple tea garden soil into different particle size of soil components by physical methods（0.002 mm,0.02~0.002 mm,0.2~0.02 mm,2~0.2 mm）,adsorption and desorption behavior of potassium through kinetic and thermodynamic methods were carried out,respectively.K＋ adsorption capacity of different size fractions of purple soil indicated less than 0.002 mm 0.02~0.002 mm of the original soil（0.2~0.02 mm,2~0.2 mm）,while desorption was the law to the contrary.By the Elovich equation,the two-constant equation,parabolic diffusion equation and lst-grade diffusion equation to fit the dynamics data of K＋ adsorption and desorption,at the same time,by the Langmuir,Freundlich and Temkin thermodynamic equations to fit the adsorption process,the results showed that the K＋ adsorption quantity which came from the composition of original soil＇s each size fractions increased with the increasing of initial concentration of K＋,but there was vastly different relationship of each size fractions-composition＇s adsorption quantity,and K＋ enriched toward the minimum size fractions.Elovich adsorption equations was the best equations to fit the K＋ adsorption and desorption characteristics of the original soil and each size fractions-composition with kinetic methods.Freundlich adsorption equations was the best equations to fit the K＋ adsorption and desorption characteristics of the original soil and each size fractions-composition and the soil of removing organic matter and free iron oxide with thermodynamic methods.