Preparation And Characterization Of PAEs Molecularly Imprinted Polymer Based On Metal-Organic Frameworks

Phthalic acid esters,also known as phthalates?PAEs?,it is the most widely used plasticizer in the modern industry,with the most varieties and the largest output.Since most plastics are not biodegradable,they are not only found on land but also in the atmosphere and in the marine environment.In daily life,it is becoming more and more commonfor the use of plastic bags,plastic lunch boxes,cling film,etc.The use of phthalates has led to the introduction and migration of phthalates into the environment,causing pollution,which in turn affects people's health through the food chain.Studies have shown that exposure to phthalates can be harmful to health,and phthalates are estrogens,androgens,and anti-thyroid endocrine disruptors in animals;Phthalates are associated with decreased thyroid function and reproductive hormones in the general population and in pregnant women.With the emphasis on the problem of the study of the toxicity and physicochemical properties of phthalates,the detection of phthalates has been a research hotspot based on phthalate residues.Molecularly imprinted technology?MIT?,also called molecular template technology,is a molecular recognition technology that has rapidly developed in recent years for preparing polymers with specific recognition sites.MIPs is characterized by its predictability,practicability and specificity.Molecular imprinting technology is widely used for solid-phase extraction.Compared with traditional solid phase extraction,molecular imprinting combined with solid phase extraction can more effectively separate and enrich target compounds.The method is simple and easy to implement,it has good selectivity,high recovery rate and high specific adsorption for the extract,it improves the selectivity of the solid phase extraction.Therefore,molecularly imprinted solid phase extraction columns are widely used in food safety analysis,medicine,and pesticide residue detection.In this paper,MOF-5 was synthesized by hydrothermal method with Zn?N0₃?₂·6H₂0?zinc nitrate hexahydrate?as dominant,H₂BDC?terephthalic acid?as an organic ligand,and N,N-dimethylamide?DMF?as solvent.A new composite MIPs@MOF-5 with higher specificity,sensitivity and stability has been successfully prepared,with dibutyl phthalate?DBP?as template molecule,MOF-5 as support carrier,methacrylic acid?MAA?as functional monomer,ethylene glycol Dimethacrylate?EDMA?as cross-linking agent and azobisisobutyronitrile?AIBN?as initiator.The MIPs@MOF-5 was characterized by Fourier transform infrared?FT-IR?.The scatchard plot suggested that MIPs@MOF-5 had two site of adsorption behavior with the dissociation constant of 0.895mmol/L,33.79mg/g,and the max adsorpyion capacity of 0.172mmol/L,59.417mg/g respectively.Selective binding experiments showed that MIPs@MOF-5 exhibited good recognition ability and higher selectivity compared with NIPs@MOF-5.The experiment of regeneration recycles with six times showed the regeneration ability of DBP was only reduced by 12.2%.The Sips model is more suitable for fitting the adsorption isotherm model of MIPs@MOF-5.The value of 1/n of MIPs@MOF-5 was 1.071,which hinted that its surface structure inclines to be homogeneous.A molecularly imprinted polymer?-CD@MIPs@MOF-5,a bifunctional monomer supported on a metal organic framework,was synthesized.With MAA?methacrylic acid?and modified?-CD as functional monomers,DPP?dipentyl phthalate?as template molecule,and MOF-5 as support carrier,ethylene glycol Dimethacrylate?EDMA?as cross-linking agent and azobisisobutyronitrile?AIBN?as initiator.The?-CD@MIPs@MOF-5 were characterized by Fourier transform infrared?FT-IR?and SEM.By SEM,it can be seen that?-CD@NIPs@MOF-5 is relatively smoothly,while?-CD@MIPs@MOF-5 is obvious imprinted holes.The scatchard plot suggested that?-CD@MIPs@MOF-5 had two site of adsorption behavior with the dissociation constant of 0.101mmol/L,12.175mg/g,and the max adsorpyion capacity of 0.584mmol/L,49.26mg/g respectively.Selective binding experiments showed that?-CD@MIPs@MOF-5 exhibited good recognition ability and higher selectivity compared with?-CD@NIPs@MOF-5.The Sips model is more suitable for fitting the adsorption isotherm model of?-CD@MIPs@MOF-5.The value of 1/n of?-CD@MIPs@MOF-5 was 1.083,which hinted that its surface structure inclines to be homogeneous.Through selective experiments,the DMP,DEP,DNOP,DMT,and DAIP adsorption capacity ratios of DPP are between 1.86 and 3.87,and their specific adsorption effects are relatively poor.But?-CD-MIPs@MOF-5 pairs of DPP have excellent specificity selection.By optimizing the experimental conditions,acetonitrile was selected as the best eluent,and 0.4 mL of acetonitrile was selected.When the volume of hexane was 0.2 mL by optimized conditions,the recoveries of DPP in the sample are 94.86±0.58%.For the water sample detection,the recoveries of DPP are 89.34%⁹3.76%,and RSD is between 3.28%⁶.31%.