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采用平衡法研究了含有机质粗粘粒、去有机质粗粘粒、含有机质细粘粒和去有机质细粘粒4种红壤胶粒对DNA的吸附特征及其热力学特性.结果表明:4种红壤胶粒对DNA的吸附是快反应过程,Langmuir吸附方程可较好地描述4种红壤胶体对DNA的等温吸附,相应拟合的相关系数r2分别为0.974、0.991、0.958和0.975.最大吸附量表现为含有机质细粘粒>去有机质细粘粒>含有机质粗粘粒>去有机质粗粘粒.电解质浓度和种类及吸附体系pH是影响红壤胶体对DNA吸附的重要因子,一定电解质浓度范围(NaCl<60mmol·L-1,CaCl2<10mmol·L-1)内,DNA在红壤胶体表面的吸附量随电解质浓度的增大而显著增加,其中钙离子的促进作用大于钠离子,但随着吸附体系pH的上升而显著降低.含有机质胶粒对DNA的吸附过程是吸热反应,而去有机质胶粒对DNA的吸附过程是放热反应,红壤胶粒对DNA的吸附反应过程是一个熵增过程.
The adsorption characteristics and thermodynamic properties of four kinds of red soil colloids containing organic coarse clay, organic matter coarse clay, organic fine clay and organic matter fine clay were studied by using the equilibrium method.The results showed that four kinds of red clay The adsorption of DNA by the particle is a fast reaction process. Langmuir adsorption equation can describe the isothermal adsorption of DNA on four red soil colloids. The correlation coefficients r2 are 0.974, 0.991, 0.958 and 0.975, respectively. The maximum adsorption capacity is Electrolyte concentration and species and adsorption system pH are the important factors that affect the adsorption of DNA on red soil colloids. A certain electrolyte concentration range (NaCl < 60mmol·L-1, CaCl2 <10mmol·L-1), the amount of DNA adsorbed on the red soil colloids increased with the increase of electrolyte concentration, and the promotion of calcium ion was greater than that of sodium ion. However, The adsorption of DNA to DNA with organic micelles is an endothermic reaction, whereas the adsorption of DNA to organic micelles is exothermic, and the adsorption of DNA by red soil micelles is an entropy increasing process.