| With the amount and type of organic pollutants growing, the natural ecosystems and human health are affected. It is of great significance to sample these pollutants rapildly. According to various estimates, sampling and sample prepraration typically account for 70-90% of analysis time. Being convenient and fast, passive sampling is not affected by the sudden pollution incidents. At present, the equilibrium passive samplers mainly include passive diffusion bag samplers, semi-permeable membrane devices, solid-phase microextraction, diffusive equilibrium in thin films. However, there are many problems, for instance, the balance time is too long and usullay fit for the hydrophobic organic pollutants. Cyclodextrin polymers is characteristic of hydrogel structure, short balance time of adsorption, a number of adsorption activity sites, molecular recognition function and structural diversity. In this study, preparation of β-cyclodextrin polymer using reverse emulsion polymerization method was conducted and then the morphology and structure were characterized. In addition, fitting isothermal adsorption equations, studying the effects of environmental factors on the adsorption and calculating elution recovery of targets are also used in this study to investigate the adsorption properties of materials. Based on the the above background, the equilibrium passive sampler is designed and then processed setting cyclodextrin polymers as adsorbents. Apply the sampler into actual water sampling and the results were as follows,β-cyclodextrin polymers was prepared by reverse emulsion polymerization, screening them with 80-120 mesh size and characterizing the morphology and structure. The adsorbents are homogeneous spherical particles. After swelling, the frequency distributions of the particle size are close to lognormal distribution and the average particle size diameter is 371.00 μm with concentrated distribution of particle size. The swelling rate is 8.67 g/g and CD element content is 68.81%. The pore size is 5.60 nm belonging to mesoporous range.Then the adsorption properties of β-cyclodextrin polymer are analyzed. After 26 kinds of target compounds(such as atrazine, fenamiphos, thiabendazole, hydrochlorothiazide, sulfathiazole, sulfapyridine, etc.)are selected, the isothermal adsorption equations are fitted by sequencing batch isothermal adsorption experiment. The target compounds are in line with the isothermal adsorption equation of Freundlich (R2> 0.96). The effects of ionic strength (Ca2+ Mg2+) and dissolved organic matter (DOM) on the adsorption are investigated. The results show that substances are not affected by environmental factors. The recoveries of the pollutants are investigated. The recoveries of most substances are between 70- 110%, and the relative deviations are within 10%.Considering the characteristic that cyclodextrin polymer swelling is not easy to be attached to the surface of the sampler, the sampler is designed into ellipsoidal shape.304 stainless steel is characteristic of corrosion resistance, good mechanical properties and no adsorption on pollutants, so we use it for subsequent processing. According to swelling volume 1.3 cm3 and ellipsoidal volume formula, get the sampler semimajor axis of 0.85cm, semiminor axis of 0.85cm, with 0.43cm in half height. Through the mold manufacturing, stamping, wrapping, welding lock, processing, products was made for actual water test. Selecting sulfadiazine, sulfathiazole, sulfapyridine, linmycin, sulfadimethoxine, results show that the accuracies in Ce,pred value of sulfathiazole and sulfapyridine are 93% -116%. While for sulfadiazine, lincomycin and sulfadimethoxine, they are 54%-62%. Because the sampler is preliminary designed, it remains to be further optimized... |
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