Preparation Of Thermosensitive Molecularly Imprinted Polymers And Its Application In The Analysis Of Sulfamethazine

Sulfonamides are a kind of synthetic antimicrobials,which have been widely used due to their advantages of quick effect on the treatment of poultry diseases and low price.However,in recent years,sulfonamides were illegal used or misused,which led to some food of animal origin containing SAs residues.At the same time,sulfonamides could be discharged into the soil and water environment through various channels,leading the soil and water to be contaminated.At last,SAs residues in the environment would enter human body via the transfer and enrichment of food chain.As we all known,SAs excessive residue could bring great harm to human health,for example,causing allergic reactions,liver poisoning,affecting our body's urinary system and causing cancer.Therefore,it is of great practical significance to have effective ways to the enrichment,separation,detection and analysis of sulfonamides of environmental samples.Molecularly imprinted polymers?MIPs?are a kind of new intelligent materials prepared by molecular imprinting technology,which are simulated of recognition mechanism of antigen,antibody and enzyme,substrate.MIPs have specific recognition abilities to template molecules,because the tailor-made recognition sites formed in the polymers are complementary in shape,size and functionality to the target molecules.In recent years,the stimulus responsive molecularly imprinted materials have become a rather popular research direction.Because the spatial structure of recognition sites in the molecularly imprinted materials will change upon the stimulus signal such as temperature,light and pH changed,so as to realize the adsorption and release behavior of molecularly imprinted polymers.In this work,two kinds of thermoresponsive molecularly imprinted polymers for selective recognition of sulfamethazine?SMZ?based on different carriers were synthesized.N-isopropylacrylamide?NIPAM?was selected as a thermosensitive monomer and Methacrylic acid?MAA?worked as additional monomer.The prepared polymers were analyzed by FTIR,TEM,XRD,TGA characterization methods.Then,we also studied the adsorption properties of MIPs and NIPs.Finally,the molecularly imprinted polymers were used as adsorbents applied in the separation and analysis of SMZ from actual water samples.This article mainly includes two aspects as follows:?1?The Si O₂ nanoparticles with uniform particle size were synthesized by using sol-gel technology,then these nanoparticles were modified by grafting C=C double bond,and then the polymers were prepared in the presence of crosslinking agent,initiator and porogen after the self-assembly of the template and functional monomers.The types and contents of crosslinking agents would influence adsorption capabilities of MIPs.So,we designed three groups of contrast experiment of MIPs with different crosslinking agents,and we compared the equilibrium adsorption capabilities and hydrophilicity of the polymers in order to ensure the best experimental group.The results of adsorption kinetic experiments showed that the adsorption process of MIPs accorded with the pseudo-second-order adsorption kinetics model,which meant that the recognition way of MIPs was mainly chemical adsorption.The adsorption of MIPs leveled off and remained constant after 80 min,and the adsorption quantity can reach 8.1mg/g.While the non-imprinted polymers?NIPs?was more in line with the pseudoone-order adsorption kinetics model,which meant that the recognition way of NIPs mainly depended on physical adsorption.Moreover,at 35?,the adsorption isotherm of MIPs for SMZ was more in accordance with the Freundlich model,and NIPs was more in keeping with the Langmuir model.This showed that the adsorption mechanisms of MIPs and NIPs were different.?2?The magnetic nanoparticles with good dispersion were synthesized by hydrothermal method.And then the thermosensitive molecularly imprinted polymers?TMIPs?were successfully prepared on the surface of the functionalized magnetic nanoparticles.This kind polymers could be rapidly separated from sample solutions by an external magnetic field,bacause the carriers had superparamagnetism.What's more,the polymers were sensitive to temperature and the structure of polymers would undergo volume phase transitions upon the temperature changed.Meanwhile,the adsorption capacities of the TMIPs reached the maximum at 35?,about 18.9 mg/g.After adsorption and desorption for five cycles,only 10.4 % loss was observed for the binding capacities of TMIPs.Finally,the imprinted polymers were used for the enrichment of SMZ from real water with recoveries ranging from 83.2 % to 96.8 %.