氟尿嘧啶与磁性层状复合氢氧化物的离子交换反应动力学

Ion Exchange Reaction Kinetics of Magnetic Layered Double Hydroxides with 5-Fluorouracil

以共沉淀法合成的磁性层状复合氢氧化物(Magnetic layered double hydroxide,MLDH)为前驱体,通过对原位反应系统液相数据的拟合与固相样品的表征,研究了0～50℃条件下MLDH与氟尿嘧啶(5-FU)的离子交换动力学特征.结果表明,MLDH及离子交换产物MLDH-FU为以六方晶系为主并混杂微量氧化铁的复合磁性晶相;MLDH-FU离子交换速率随温度的升高而显著加快,FU,OH-和Cl-3种客体的浓度变化分别服从二级、零级及一级反应速率模型,反应活化能依次为12.69,27.88和3.580 kJ/mol.固相表征参数的变化与液相动力学过程、主-客体结构调整及MLDH-FU粒子陈化过程相符;离子交换限定在LDH层间,不涉及层板内部秩序,不改变前驱体的结构与形貌特征,具有侧向非断层反应习性,是交换剂在MLDH外周经吸附亲和、侧向进攻、层间置换及柱撑模型转换再到新的插层客体主导调整及晶粒发育陈化的有序过程.

Using the magnetic layered double hydroxides（MLDH） synthesized by co-precipitation as a precursor,the dynamic feature of ion exchange reaction between MLDH and fluorouracil（FU） under the condition of 0—50 ℃ was investigated via the liquid data fitting and solid-phase characterization of MLDH-fluorouracil in situ reaction system.The results show that MLDH and product MLDH-FU belonged principally to a six square crystal series（R-space group） are magnetic compound crystal phase mixed trace iron oxide.The ion exchange rate of MLDH-FU increases significantly with the increase of temperature,and the concentrations varying of three object FU,OH-and Cl-,respectively,obey the secondary reaction,zero-order reaction and first-order reaction rate models,the reaction activation energy are 12.69,27.88 and 3.580 kJ/mol,respectively.Cha-racterization parameters of solid-phase samples change with the liquid kinetic process,object structure adjustment and particle development process of MLDH-FU.Ion exchange limited within interval of LDH layers dones＇t affect the internal structure order of layers,and doesn＇t change the structure and layered morphology characteristics of precursor,with a non-break-layer reaction behavior.The ion exchange reaction between MLDH and FU is an orderly process started from the absorption affinity of exchange agent FU in MLDH peripheral,lateral offensive,interlayer displacement,and transformation in pillared model to a structure adjustment leaded by the new intercalated object,and grain development process.