Design And Construction Of Molecularly Imprinted Membrane And Its Application In The Analysis Of Organic Pollutants

Various organic pollutants in the environment not only cause serious harm to human health,but also cause immeasurable losses to the ecosystem.In recent years,organophosphate flame retardants and various chiral pesticides have been widely used.Organophosphate flame retardants are harmful to humans and aquatic organisms,so they are urgently needed to be tested.The different configurations of chiral pesticides have great differences in efficacy,so the selective resolution of their single configuration is very important.Based on this,scientists have developed a variety of detection environment organophosphate and chiral pesticide single configuration selective resolution method.However,there are some unsolvable shortcomings in the past research,such as:the traditional detection methods such as chromatography or mass spectrometry require expensive equipment,the sample processing process is cumbersome;the traditional chiral separation material separation efficiency is low.Therefore,the development of high-selectivity and high-affinity identification materials and simple,fast,sensitive,and real-time detection methods are the main challenges facing the analysis of organic pollutants in the environment.The molecularly imprinted membrane materials developed on the basis of molecular imprinting technology have the advantages of high specificity,large surface area,and high recognition site efficiency.At present,they are widely studied in the fields of recognition detection and chiral separation as selective recognition materials.Combining molecularly imprinted membrane extraction with electrochemical detection to establish an integrated enrichment-detection online detection method can realize real-time,on-site,rapid and sensitive detection of organophosphates.Therefore,based on the advantages of molecularly imprinted membrane specific recognition and electrochemical detection of real-time,fast and sensitive,this paper analyzes the organic pollutants as follows:1.Construct a composite molecularly imprinted membrane for the highly specific recognition of triphenyl phosphate(TPhP)in environmental water samples.Polyethylene terephthalate(PET)was used as the base material,and its surface was modified by silanization.Then,using TPhP as the template molecule,acrylamide as the functional monomer,and ethylene glycol dimethacrylate as the cross-linking agent,the TPhP molecularly imprinted prepolymer solution was prepared by ultrasonic dispersion.Finally,the silanized PET film was added to a certain amount of prepolymerization solution,and the TPhP composite molecularly imprinted film was successfully prepared by the UV-induced surface grafting technology.The modification process of the base material and the composite film material were characterized by in-situ attenuated total reflection infrared spectroscopy,contact angle test,scanning electron microscope,specific surface meter and thermogravimetric analyzer.The results showed that the composite film material was successfully prepared,and It has the advantages of large surface area,good chemical and thermal stability.2.The study on the adsorption performance of TPhP composite molecularly imprinted membrane and the establishment and application of an online analysis method combining membrane extraction and ion rectification testing.The effects of time and concentration on the current response of membrane materials were studied by adsorption kinetics and isotherm experiments.Through adsorption kinetic experiments,it is found that the composite molecularly imprinted membrane can reach adsorption equilibrium within 20 minutes.Through isothermal experiments,it can be found that the maximum adsorption response of the composite molecularly imprinted membrane to template molecules is far greater than the maximum adsorption response of the composite non-molecularly imprinted membrane to template molecules.The extraction selectivity of the TPhP composite molecularly imprinted membrane to template molecules was studied.The results showed that the composite membrane has good selectivity.Subsequently,we fixed the triphenyl phosphate composite molecularly imprinted membrane in an electrolytic cell,and tested its current response by ion rectification test under optimal membrane extraction conditions,and established a combination of molecularly imprinted membrane extraction and ion rectification test(MIME-IR)Online analysis method.The experimental results show that there is a good linear relationship between the logarithm of the target concentration and the current response in the range of 0.001-800 ng/mL,and the detection limit of this method can reach 0.0003 ng/mL.The relative standard deviations of intra-day,inter-day and different batches of membranes were 2.1%,4.4%,and 5.3%,respectively.Finally,the four actual water samples were recovered with standard addition,and the recovery rate was between 74.5%and 108.7%.Experimental results show that this method can be used for the simple,rapid and real-time detection of TPhP in environmental water samples.3.In addition to the application of molecularly imprinted membranes in recognition and detection,they also have unique advantages in chiral recognition and resolution.Based on this,we prepared the S-TDF molecularly imprinted membrane and studied its chiral resolution performance.Using S-TDF as template molecule,acrylamide and allene column[5]aromatic hydrocarbons as functional monomers,two-monomer molecularly imprinted membrane(MIM-?),single monomer molecularly imprinted membrane(MIM-I)and non-molecularly imprinted membrane(NIM)were successfully prepared.The film materials were characterized by infrared spectroscopy,scanning electron microscope,X-ray photoelectron spectroscopy,and thermal stability.The transmembrane selectivity of the three membrane materials to S/R-TDF was studied by ultraviolet transmission experiment.UV transmission experiments show that MIM-? has the best transmembrane selectivity coefficient,?(S/R)=5.11,while the selectivity coefficients of MIM-I and NIM are 3.16 and 1.47,respectively.Enantiomeric resolution experiments were conducted to study the chiral resolution performance of the three membrane materials,and their resolution results were tested by high performance liquid chromatography.Experiments show that MIM-?has the best chiral resolution performance.Under the optimal separation conditions,the separation efficiency of enantiomeric excess e.e.%=84.78%can be achieved by using MIM-? for two separations.