Radyasyonla Başlatılan Aşılama ve Polimerizasyon Yöntemleri İle Atrazin Baskılı Polimerlerin Hazırla

Abstract

Molecularly imprinted polymers (MIPs) are used in a wide range of applications such as chromatography, sensing systems, solid-phase extraction (SPE) as recognition materials for various template molecules like pesticides, herbicides, amino acids, proteins and drugs due to properties like specific selectivity, easy preparation, high chemical and physical stability. Triazine group compounds are well known and widely used herbicides to improve the yield and quality of the products in agriculture. Besides their benefits, these compounds and their derivatives are major source of contaminations in ground water, soil and some organisms. The widely used member of this family is atrazine due to its price and better efficiency. The long term uses of atrazine causes an accumulation in water and soil which results in potential health problems such as cancer, weight loss, birth defects and disorder in hormone functionality. In order to control and minimize the effects of this compound on human health and environment development of an easy and reliable analysis method is a very important issue. In this study atrazine imprinted polymers were prepared by using different methods such as precipitation polymerization, in-situ polymerization and grafting onto PE/PP non-woven fabrics via gamma irradiation. Before synthesis step, functional monomer and functional monomer/template molecule ratio were determined by combinatorial approach. Methacrylic acid was selected as vii functional monomer and functional monomer/template molecule ratio was determined as 2/1. Then atrazine imprinted membranes, micro spheres and grafted polymers were prepared via in-situ polymerization/crosslinking, precipitation polymerization and grafting onto PE/PP non-woven fabrics, respectively. These imprinted polymers were characterized by using different methods. In the AFM (atomic force microscopy) and SEM (scanning electron microscopy) analyses, it was observed that the presence of template molecule imparts homogenity to the topology of imprinted membranes. According to SEM results the thickness of PE/PP non-wowen fabric fibers was seen to increase from 12.7±1.8 m to 19.0±2.0 m due to the grafting of imprinted polymer while the average diameter of the micro spheres is calculated as 200 nm in dry state. Zetasizer analysis indicates that the polydispersity index (PDI) of these micro spheres is 0.126. In the positron annihilation lifetime spectroscopy (PALS) analysis it was observed that presence of atrazine causes a decreasing in the size distribution of free volume holes while an increasing in the size of holes in the matrix. Binding characteristics were investigated as a function of various factors such as concentration of template molecule, pH and time. Evaluation of adsorption isotherms showed Bi-Langmuir behaviour for atrazine imprinted polymers. Results of kinetic studies showed that imprinted polymers showed pseudo second order kinetics where adsorption was chemically controlled. Finally specific binding experiments were carried out for atrazine imprinted polymers using molecules with similiar chemical structures, namely simazine and metribuzine. While the lowest selectivity coefficients were determined for imprinted micro spheres, it was seen that atrazine imprinted polymers grafted onto PE/PP non-woven fabrics presented the highest selectivity for atrazine with selectivity coefficients of 2.11 and 2.28 times higher compared to those for simazine and metribuzine, respectively.