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

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。

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

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.