摘要
氯吡脲(Forchlorfenuron,简称CPPU)是水果、蔬菜等常用的一种膨大剂,它的分子印迹聚合物(molecularly imprinted polymer,简称MIP)印迹吸附自身模板分子的机理对今后应用MIP吸附清除蔬果残留CPPU及其监测具有重要的理论意义。基于界面双电层变化的零流电位法在研究物质之间的相互作用方面有显著的优势。据此,在293.15 K下,采用零流电位法,以MIP印迹吸附模板分子前后零流电位变化率作为吸附容量,考察了电化学聚合法所制备的氯吡脲分子印迹聚合物(CPPU-MIP)印迹吸附模板分子CPPU的等温模型、吸附机理和动力学反应特点。结果发现:所拟合的7种等温模型(Langmuir、Freundilich、Langmuir-Freundlich、Dubinin-Radushkevich、Temkin、Henry以及BET)中,只有Langmuir-Freundlich和BET方程更适合描述CPPU-MIP对CPPU的吸附,显示单分子层与多分子层吸附共存的特点;在0~240 s范围内,CPPU-MIP对CPPU的吸附过程可分为快速吸附、慢速吸附和趋于平衡3个阶段,其中前30 s即可完成快速吸附,可达到79.7%的吸附率,超过90 s后趋于饱和平衡;在拟合的Elovich、准一级和准二级3种动力学方程中只有准二级动力学方程更能反映CPPU-MIP吸附模板分子的动力学过程,说明该吸附有化学键形成;对CPPU-MIP的吸附容量与吸附时间的平方根关系曲线研究发现其并不过原点,进一步说明CPPU-MIP对CPPU的吸附呈现孔扩散和化学吸附共存的吸附机制。
Forchlorfenuron(CPPU)is a commonly used expansion agent for fruits and vegetables.The adsorption mechanism of its molecularly imprinted polymer(MIP)on its own molecules is of great theoretical value for removing residual CPPU by MIP adsorption in fruits and vegetables in the future.The zero-current potential method based on the change of the interface double electric layer has significant advantages in studying the interaction between substances.Therefore,the isothermal model,adsorption mechanism and kinetic reaction characteristics of the molecular imprinted polymer(CPPU-MIP)prepared by electrochemical polymerization were investigated at 293.15 K by using the zero current potential method and the change rate of zero current potential before and after the MIP imprinted adsorption template molecules as the adsorption capacity.The results showed that in the seven isothermal models(Langmuir,Freundilich,Langmuir-Freundlich,Dubinin-Radushkevich,Temkin,Henry and BET),Langmuir-Freundlich and BET equations were more suitable to describe the adsorption characteristics of CPPU by CPPU-MIP,which showed the coexistence of monolayer and multi-layer adsorption;In the range of 0~240 s,the adsorption process of CPPU-MIP to CPPU could be divided into three stages:rapid adsorption,slow adsorption and equilibrium.The rapid adsorption could be completed in the first 30 s,and the adsorption rate was up to 79.7%,which reached saturation equilibrium after 90 s.Among the Elovich,pseudo-first-order and pseudo-second-order kinetic equations,only the pseudo-second-order kinetic equation could better reflect the kinetic process of CPPU-MIP adsorption template molecules,indicating that the adsorption had chemical bond formation.The plot of adsorption capacity vs.square root adsorption time did not reach the origin,which further indicated that the adsorption mechanism of CPPU-MIP to CPPU was the coexistence of pore diffusion and chemisorption.
作者
马明明
何成毅
崔淑慧
刘佳
MA Ming-ming;HE Cheng-yi;CUI Shu-hui;LIU Jia(School of Environmental and Chemical Engineering,Xi’an Polytechnic University,Xi’an 710048,China;Center for quality and safety inspection and testing of agricultural products of Xi’an city,Xi’an 710077,China)
出处
《化学研究与应用》
CAS
CSCD
北大核心
2022年第5期1008-1015,共8页
Chemical Research and Application
基金
陕西省科技重点项目(2020GY-238)资助
西安市科技计划项目(20NYYF0047)资助。
关键词
零流电位法
氯吡脲
分子印迹聚合物
等温吸附模型
吸附动力学
zero current potentials
forchlorfenuron
molecularly imprinted polymer
isothermal adsorption model
adsorption kinetics
