Preparation Of Biphenyl Molecularly Imprinted Polymers And Application On The Remediation Of Contaminated Soils

Polychlorinated biphenyls?PCBs?pollution increased dramatically,which directly influences human survival and development.PCBs are highly toxic and is difficult to be eliminated by common methods in soil environment with highly PCBs pollution due to its extremely stable physical and chemical properties.The molecular imprinted polymers made by molecular imprinting technology of incresing availablity has strongly specific adsorption effects.The ozone-UV technology has been thought to remove PCBs effectively because of its ability to restore the degradation of organic chlorides in recent report.In this paper,we combined with the molecular imprinting,ozone and ultraviolet technique,which can provide a new method for soil remediation,even a new opportunities for the removal of PCBs in polluted soil.In this study,we use there compounds?biphenyl,PCB11 and PCB28?,the template of biphenyl molecular imprinted polymers?MIP?of and ?-methacrylic acid?MAA?as the functional monomer to synthesis substances which have spatial structure of a biphenyl pores imprinted polymer.PCBs in the soil can be adsorbed by the polymer,then we make use of ozone-UV method to degrade PCBs which adsorbed by MIP.We expect to provide a theoretical basis for restoring contaminated soil by studying under influence of different factors.The contents and results are as follows:1.With biphenyl as template molecular,methacrylic acid and ethylene glycol dimethacrylate?EDMA?and 2,2-azo different nitrile?AIBN?respectively functional monomer,crosslinking agent and initiator and acetonitrile as the solvent,by ultrasonic dissolving,polymerization,elution steps with biphenyl substances cavities of molecularly imprinted polymer.Through the study of solvent species,biphenyl,MAA and EDMA different ratio and elution reagent kinds of MIP adsorption performance influence to determine the biphenyl molecular imprinted polymer of preparation conditions: with biphenyl as template molecule and acetonitrile as the solvent,MAA as functional monomer,the molar ratio of biphenyl,MAA and EDMA is 1:3:40 and hexane eluting reagent.2.The surface pore characteristics and the integrity of biphenyl MIP were characterized by scanning electron microscopy?SEM?.Results showed that elution of MIP and non imprinted polymer?NMIP?surface cavity less,texture more closely;and after elution of MIP surface roughness,hole is larger and much more,loose texture.Analysis showed that surface roughness of polymers with cavity is biphenyl molecules are eluted after left,the cavity is conducive to the combination of substrate molecules and molecular imprinted polymer,so that the MIP to the substrate has high recognition and high load capacity.The structure of MIP was characterized by Fourier infrared spectroscopy?FTIR?,and the results showed that the hydrogen bond between template and functional monomer in the process of preparation was demonstrated.3.Synthesis and after elution of biphenyl MIP,after grinding were a 200 mesh?58 ?m?and 250 mesh sieve?75 ?m?,comparison of three different particle size of MIP adsorption properties.The results showed that grain size of 200-250 purpose polymer adsorption effect is better than the other two groups.Optimal conditions for the MIP to the soil solution biphenyl and PCBs adsorption found: when the adsorption medium volume ratio is 1:4 acetone water,initial pH of solution is 7,the temperature is 20?,the adsorption effect of MIP to biphenyl,PCB11 and PCB28 were best and adsorption rate were above 95%,higher temperature or lower and acid and alkali environment will inhibit the adsorption.Using Lagrange second order kinetics equation fitting the kinetic curves obtained the correlation coefficient of the linear equation were about 0.99.The fitting effect well,which indicates that in the MIP,the adsorption process of both physical adsorption and chemical adsorption.4.The MIP was degraded by ozone UV method and the degradation products were analyzed by GC-MS,only the dichloro-diphenyl and biphenyl were detected in the product.The degradation pathways for PCB28 speculates that by UV / O₃ combination process of reductive dechlorination,target substance PCB28 first off a chlorine atom dichloro diphenyl generation,then gradually take off the two chlorine atoms to produce biphenyl.No chlorine was detected in the experiment,because of the extremely unstable of chlorine,and the chlorine can be removed immediately after the ozone and ultraviolet double action.