| Antibiotics are used extensively in human and veterinary medicine for controlling disease and also in livestock feed. Consequently, they would be discharged into aquatic environments through domestic wastewater effluent, disposal of expired antibiotics, and excretion from organism. Discharged antibiotics could accumulate along with food chain in living beings’body which could cause drug resistant genes spreading. Thus, it is extremely essential to develop efficient and economic treatment technologies for removing antibiotics.Since adsorbents are of large surface area and abundant pore structure, such as carbon nanotubes, activated carbons, and porous resins, they have shown great potential in removing undesirable organic contaminants from aqueous solutions. Among these sorbents, synthetic resins attract great attention according to their much better regeneration performance compared to engineered carbons’.However, so far the resin-based adsorption technologies haven’t been widely used in full-scale application of water treatment. It is mainly on account of the typically used fixed bed process of resin adsorption, which mostly limits the flux and increased the costs. In recent years, magnetic resins have been developed and are considered to be a promising sorbent for water treatment. Due to their convenient separation characteristic, the magnetic resins have already successfully been used in a completely-mixed contactor process for wastewater treatment. This process could dramatically increase the water treatment amounts and decrease the costs compared with fixed-bed, extending the use of resins in micropolluted water purification.So far, studies addressing antibiotics removal by magnetic resins are still scarce. The most commonly used anion exchange magnetic resin MIEX(?), was found to be effective for adsorption of antibiotics with great electronegativity. But the removal performance of these antibiotics would mostly deteriorate according to competition with anionic natural organic compounds (NOMs) in aquatic environment. Besides the ion exchange magnetic resins, non-magnetic adsorption resins with hydrophobic skeleton were also demonstrated to be efficient materials for antibiotics removal because of their large surface area. It has been found that the hypercrosslinked structure, high surface area, and suitable pore size distribution were all critical factors of adsorbents for antibiotic removing. But until now, most of developed magnetic resins have mainly focused on surface modification with functional groups, few studies have reported on the preparation of magnetic resins with high surface areas.The main objective of the present study is to identify and evaluate the performance of four kinds of resin in the removal of tetracycline, two of them are novel porous magnetic resin, M150, M80. Besides, two non-magnetic resins, NDA150(hypercrosslinked), XAD-4(macroporous) were selected as adsorbents, in order to investigate the adsorption behavior and predominant factors controlling the adsorption of antibiotics onto the adsorbents. A commonly used antibiotic, tetracycline (TC), was examined as adsorbate in batch adsorption experiments. The effects of solution chemistry conditions (pH, ionic strength) and temperature on adsorption were evaluated. Because of large surface area and abundant pore structure, magnetic resin M150absorbs tetracycline quickly and plentifully. Besides, the magnetism of M150brings fluid-bed processing of resin into reality, which will not only increase efficiency of adsorption but also decrease the cost. In the background with low concentration of Cu2+, adsorption of tetracycline by magnetic resins are increased, especially M150, but also M80. Magnetic resin M150also shows a ideal performance with residence of natural organic matter. |
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