| With rapid economic and social development of China, environmental pollution events occur frequently, especially explosions, leaks, and secretly emissions. The organic pollutants, especially persistent organic pollutants (POPs) from these serious environmental pollution accidents, have caused the pollution of groundwater, and seriously threatened human health, eco-environment and social security. The increasing worldwide contamination of freshwater systems with thousands of industrial and natural chemical compounds is one of the key environmental problems. Although most of these compounds exist as low concentration, many of them have considerable toxicological problems. Adsorption as a kind of operating convenience, promptness wastewater treatment method is ineffect to treat micro-polluted water caused by organic pollutants at low low concentration levels. Therefore it is important to develop an efficient, low-cost adsorbent used in micro-polluted water treatment.β-cyclodextrin consists of a hydrophilic outer edge and a hydrophobic inner cavity. Hydroxyl groups on the hydrophilic outer edge makeβ-cyclodextrin have certain degree of solubility in water, and the hydroxyl groups can chelate with high valence metal ions. The ring structure and the hydrophobic inner cavity makeβ-cyclodextrin include other organic or inorganic molecules to form the host-guest complexes of non-covalent bonds.β-cyclodextrin has a certain three-dimensional selection and recognition performance, which provided a selection for the removal and separation of pollutants in micro-polluted water.β-cyclodextrin is an important tool for environmental protection, and has important applications value in water purification. In this study, one type of solid insolubleβ-cyclodextrin cross-linked polymer (β-CDP) was prepared, and used for purification of BTEX and Chlorobenzenes micro-polluted water.(1)β-cyclodextrin cross-linked polymer was prepared in alkaline conditions, by epichlorohydrin as a crosslinking agent, cosslinking polymerization withβ-cyclodextrin. The product was characterized by Fourier transform infrared spectrosaopy and X-ray diffraction spectrosaopy. The results showed that after cross-linking polymerization, P-CDP still retains the cavity, which has the ability to form inclusion complex with BTEX and Chlorobenzene in micro-polluted water.(2) The performance ofβ-cyclodextrin polymer adsorbing BTEX and Chlorobenzene was investigated. The results showed that:when the initial concentration of BTEX and Chlorobenzene was 10mg/L, the removal rate of P-CDP treating BTEX and Chlorobenzene at 10min, respectively:65.28% of benzene,81.06% of toluene, 81.44% of Ethylbenzene,78.87% of Xylene, and 65.81% of Chlorobenzene. With the adsorption time increasing, the adsorption ofβ-CDP for BTEX and Chlorobenzenes gradually stabilized. The removal efficiency of Chlorobenzene was highest and reached equilibrium at 120min. BTEX reached equilibrium at 180min. In neutral condition and temperature of 25℃, the adsorption of BTEX and Chlorobenzene on P-CDP was better, and the inclusion complexes were more stable.(3) The adsorption isotherms of BTEX and Chlorobenzene onβ-CDP were investigated, and the isotherms data were fitted by Langmuir model and Freundlich modelrespectively. The results showed that the adsorption processes of BTEX and Chlorobenzenes onβ-CDP fitted Langmuir model better, which indicated the inclusion between BTEX, Chlorobenzene andβ-cyclodextrin may be the single molecule reaction. The maximum adsorption ofβ-CDP for these five pollutants at 25℃were benzene 11.09mg/g, toluene 10.62mg/g, ethylbenzene 11.19mg/g, xylene 15.46mg/g, Chlorobenzene 28.17mg/g, respectively.(4) The removal efficiency and the stability ofβ-CDP treating BTEX and Chlorobenzene micro-pollution water under continuous operating conditions were simulated. Theβ-CDP had strong inclusion ability for BTEX and Chlorobenzene in micro-pollution water, and maintained high removal rate for a long time. When hydraulic retention time was 120min, the BTEX removal efficiency was more than 65%. When hydraulic retention time was 60min, the removal efficiency of Chlorobenzene were more than 70%, and more than 80% with the hydraulic retention time of 90min.(5) The mechanism of BTEX and Chlorobenzene removed from micro-polluted water was that the contaminants were embedded in the cavity ofβ-CDP, and formed inclusion complexes with CDP. The removal process of BTEX and Chlorobenzene in micro-polluted water byβ-CDP involved in complexation processes between adsorbent and pollutants, hydrophobic interactions (the hydrophobic interactions of pollutant polymers and pollutants-pollutants) and physical adsorption based on polymer network, rather than the simple physical adsorption.(6) Adsorption saturation ofβ-CDP for BTEX and Chlorobenzene can be regenerated by ethanol elution. The adsorption capacity ofβ-CDP was increased with a certain degree at regeneration of initial several times.
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