| A variety of micropollutants, often detected at low levels, has raised toxicological concerns to humans, animals and plants, have a variety of categories. Especially, they exist as complexed pollutants, which results in difficult removal by conventional water treatment technology, and hence raising potential risks to human health and ecosystem. The effective elimination or removal technology should be developed to treat these mircopollutants. Cyclodextrin-based material, a kind of environmental friendly adsorbent, is able to separate various organic compounds from water. Due to the diversity of complexed pollutants, new adsorbents with multiple binding sites should be designed to enlarge the application scale. Pollutants are only transferred from one phase to another after adsorption. They need further treatment and regeneration of adsorbents. A combination of adsorption and oxidation can achieve high efficiency for simultaneous material regeneration and decontamination. This study aims to promote the application of cyclodextrin-based materials in water pollution control.β-cyclodextrin polymer (β-CDP) was prepared by reverse emulsion polymerization.A combination technology of CDP adsorption firstly and KMnO4green oxidation subsequently was adopted for pollutant treatment. A model pollutant of TBBPA was selected.The contact time, KMnO4concentration and degradation process were studied, as well as the characterization of the change of CDP after oxidation. Synchronization of TBBPA decontamination, CDP was regegenerated by oxidation. The removal efficiency was enhanced with the increase of contanct time or KMnO4concentration. Composite material was prepared followed the CDP regegenerated. Characterization results showed the material was microspheric morphology and a formation of MnO2nanoparticles, which embeded in β-CDP matrix. CDP can be used20times in adsorption-oxidation process with an increased MnO2loading, maintaining a perfact effect (100%) for both adsorption and oxidation process. The degradation progress could be best described by pseudo first-order kinetics. The degradation rate was decreased due to the competition reaction with KMnO4between (3-CD and TBBPA. However, the distribution of degradation products remained the same.In addition, the oxidation by KMnO4generated active manganese species (Ⅴ,Ⅵ) and finally formed colloidal MnO2detected by UV-vis spectrophotometry. Composite materials were prepared via self-controlled redox method using β-CDP and y-CDP as matrixes. The element, structure and properties were characterized and the adsorption capacities for a range of pollutants were also studied by batch adsorption experiment. Results were as follows.(1) FTIR characterization showed an obvious Mn-O vibration in the spectrum of the as-prepared material, which was proved as a composite material of MnO2and CDP matrix by qualitative and quantitative analysis of XPS, denoted MnO2/CDP.(2) SEM along with EDS demonstrated a microspheric morphology (3D structure) with density surface and uniform distribution of Mn. TEM and XRD showed the formation of MnO2nanoparticles (about～2-4nm), embeded in EPI-CDP matrix, with lattice planes corresponding to δ-MnO2and an amorphous patterns of those of CDP matrix.(3) The composite had mesoporous structure with larger pore size, less surface area and pore volume than CDP. Moreover, the composite, with a centralized distribution, showed a high performance of swelling ability and settleability in water.(4) The mass loading of MnO2, which was the product of CDP reaction wiht KMnO4, followed a good linear dependence with KMnO4concentration (R2≥0.90). This peperation method is low cost and facial operation. MnO2/CDP composites with multiple adsorption sites enlarge the application scale and showed a comprehensive adsorption for a range of different hydrophobic pollutants, especially enhancing sorption capacities toward oxytetracycline. These materials with good regeneration ability are promising in the applications of separation of complexed compounds with low levels form water. |
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