Study On Selective Extraction And Removal Of Nitrophenol Pollutants In Water Samples Using Hydrophilic Molecularly Imprinted Polymers

Molecular Imprinting Technique is a kind of molecular recognition technologies thatbased on the basic principle of antigen/antibody. The molecularly imprinted polymers(MIPs) are obtained by copolymerization of functional monomer and cross-linker in thepresence of template. Then, after removal of the template, the three-dimensional sites whichare complementary to the template in shape and functionality are revealed. For the MIPscan rebind the template and its’ analogue specifically, it is also named ‘artificial antibody’.This article focused on extraction and removal of nitrophenol pollutants in water samplesby using MIPs as sorbents. In this study, hydrophilic MIPs, which had the specificrecognition for nitrophenols in water media, were prepared by precipitation polymerization.And the hydrophilic MIPs were used to selectively extract and remove nitrophenolpollutants from water samples. The main contents were described as follows:1. To overcome the disadvantages of traditional solid-phase extraction, we developed asimple and rapid spin column extraction technology packed with hydrophilic molecularlyimprinted polymers (MIPs) for extracting nitrophenol pollutants in water samples (the EastLake, the Yangtze River and wastewater). The spin column was centrifuged for sampleloading, washing and eluting, and the whole extraction procedure could be completedwithout evaporation steps and extraction equipments. Under the optimized condition, the extraction recoveries of nitrophenol pollutants on hydrophilic MIPs-packed spin columnranged from87.3%to92.9%and excellent purification effect was obtained. Compared withactivated carbon, multi-walled carbon nanotubes, LC-C18sorbents, hydrophilic MIPsexhibited highly selective recognition ability for nitrophenol pollutants and satisfactorysample extraction efficiency. Subsequently, the MIPs-packed spin column extractioncoupled with HPLC-UV method was established to detect the nitrophenol pollutants inwater samples, which was found to be linear in the range of2-1000ng/mL(2,4-dinitropehnol,2-nitropheno), and6-1000ng/mL (4-nitrophenol)， with correlationcoefficients (R2) greater than0.998. The detection limits (LODs) ranged from0.3to0.5ng/mL，and it was shown that the intra-day RSD ranged from4.0%to6.7%and theinter-day RSD ranged from5.9%to8.2%in5days.2. Novel hydrophilic molecularly imprinted polymers (MIPs) with high adsorptioncapacity were used as the sorbents to remove2,4-dinitrophenol (2,4-DNP) from surfacewater and wastewater samples. The kinetic studies, dynamic adsorption and selectivityexperiments of hydrophilic MIPs were investigated. The results indicated that themaximum adsorption capacity of2,4-DNP on hydrophilic MIPs was138.9mg/g.Furthermore, the effects of flow rate, initial concentration, pH value and humic acid on theremoval efficiency for2,4-DNP were optimized. Compared with the active carbon, carbonnanotube, C18sorbents and common MIPs, the removal efficiency of hydrophilic MIPs(100mg) was higher with all above92%even though the sampling volume was more than1L. The results of five times adsorption-desorption cycles indicated that hydrophilic MIPswere with high stability. In a word, the obtained results demonstrated that the hydrophilicMIPs could be used as the effective sorbents for2,4-DNP removal in practical application.