| Atrazine is a kind of triazine herbicide widely used in some cereal grain such as corn and soybeans etc. It has a certain toxic effects on people, animals and plants. At present, gas chromatography, high performance liquid chromatography and gas chromatography-mass spectrometry have been mainly used to detect atrazine. Because atrazine usually exists in the form of trace content in complex samples, the pretreatment process is relatively complex and needs large reagent consumption. Moreover, common adsorbents lack specific recognition property. Therefore, exploring new solid phase extraction materials with high recognition performance and low interference has important significance in enrichment, separation and detection of atrazine.Molecular imprinting technique is a new technology developed rapidly in recent years, It aims to prepare molecularly imprinted materials with particular recognition of target molecules and highly stability. Due to well mechanical strength and heat resisting and high pressure resistant properties, as well as good selectivity for many compounds related to environment, medicine and other fields, molecular imprinted materials have been widely used in separation engineering, alkaloid extraction and biomimetic sensors.In this paper, we choose atrazine as the template molecule, methacrylic acid as functional monomer, ethylene glycol dimethyl acrylate as crosslinking, azo-bis-isobutyronitrile as initiator to polymerize at60℃, after24h, we obtained molecularly imprinted polymer nanospheres in acetonitrile solvent through precipitation polymerization. Infrared spectroscopy, scanning electron microscopy, thermal gravimetric analysis and specific surface area analyzer polymer nanospheres were used to characterize the polymer nanospheres. Binding capacity of the polymer microspheres to template molecules was investigated by static equilibrium adsorption test, which showed that the molecular imprinted polymers were formed via hydrogen bonding, the particle size was about210nm, and the surface area, pore volume and pore size were34.27m2/g,0.13cm3/g and15.4nm. Scatchard study showed that there existed two different binding sites in the molecularly imprinted polymer nanospheres. The maximum apparent adsorption capacity (Qmax) and the equilibrium dissociation constant (Kd) were Qmax1=38.08μg/g; Kd1=0.2489μg/L and Qmax2= 310.33μg/g; Kd2=6.6269μg/LWe also discussed the influence of spinning solution concentration, spinning voltage and receiving distance to the fiber diameter and surface morphology in the synthesis of atrazine molecular imprinting fiber membrane and optimized the preparation conditions. Scanning electron microscopy was used to analysis the fiber diameter distribution and overall morphology; thermal gravimetric analysis and differential scanning calorimetry were used to study the thermal stability of the polymer fiber membrane; membrane swelling, water absorption and porosity of the membrane were also studied; the molecular imprinted membrane binding capacity of the template molecule through static equilibrium adsorption experiments. The above investigations showed that under the conditions of mass fraction of the spinning liquid6.0%, spinning voltage18KV, receiving distance30cm, the diameter of atrazine imprinted fiber membrane was about170nm, glass transition temperature was119℃. The swelling rate was13.25%, water absorption was93.37%and void ratio was2.6. Scatchard analysis showed that two different binding sites existed in the molecularly imprinted polymer nanospheres. The maximum apparent adsorption capacity (Qmax) and the equilibrium dissociation constant (Kd) were Qmax1=58.12μg/g, Kd10.2060μg/L; Qmax2=273.75μg/g, Kd2=3.8956μg/L.In this article, a new method to synthesize atrazine molecularly imprinted membrane through electrospinning technology was discussed. This method can be used to prepare nanofiber membrane with specific recognition and selectivity properties, which will further promote the practical application of the molecularly imprinted membrane. |
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