四环素在海洋沉积物上的吸附

Adsorption of Tetracycline on Marine Sediment

研究了四环素在不同pH、盐度、温度下在海洋沉积物上的吸附特征.结果表明,在实验浓度范围内吸附行为都可以用线性等温式进行描述.通过一种包含四环素3种形态与沉积物界面相互作用的模型对不同pH下的吸附常数进行拟合,发现四环素正价态的吸附常数Kd+远大于中性态的K0d与负价态的Kd-.随着盐度的减小四环素在海洋沉积物上的吸附增强,而温度的升高则不利于吸附的进行.热力学计算结果得出,ΔGφ=-9.746^-9.713 kJ/mol;ΔHφ=-10.056 kJ/mol;ΔSφ<0,表明该吸附过程是一个自发的、放热的熵减过程.

Adsorption interactions of tetracycline with marine sediment were investigated under varied pH and salinity and temperatures conditions.Adsorption behavior could be fitted with linear isotherms very well over the concentration range.Adsorption edges were best described with a model,which included interactions between positive form,zwitterion form and negative form of tetracycline and marine sediment interface.It showed that the value of K-＋d was higher than K-0d and K-d.The adsorption was favorably influenced by decreasing salinity of seawater,but negatively by increasing temperatures.The result of thermodynamic function calculation showed that the change of Gibbs free energy-ΔGφ=-9.746-9.713 kJ/mol,the enthalpy change-ΔHφ=-10.056 kJ/mol and the entropy change-ΔSφ0 for the sorption.It indicated that the adsorption was a spontaneous and exothermic process which accompanied a decrease in the degree of freedom.