| Water pollution is one of the most serious problems in the current water crisis, so the treatment of water pollution cannot be delayed. Though adsorption is a high-efficient, simple technique among the methods of controlling water pollution and could be apply widely, the separation and recycle of the adsorbent are difficult. The emergence of magnetic materials, which makes the recycle of adsorbent possible, injects new vitality into the development of the adsorption technique. Due to the magnetism and large surface area of Fe3O4, these magnetic materials gained widespread attention in the areas of the development of new adsorbent materials. According to the characteristics of common pollutants in water environment, three magnetic adsorbents were designed and synthesized, and their adsorption properties were also discussed in the present paper.(1) So far many researches on the preparation of amine-functionalized magnetite particles by two steps have been reported, of which the preparation processes were complicated and the quantities of consumed detergents were high. Therefore, a facile and efficient one-pot method was applied in this paper to prepare Fe3O4-NH2nanoparticles using FeCl3·6H2O as the sole Fe source. The as-prepared material was then applied to remove the Hg (Ⅱ) ions in the water. Compared with Fe3O4that were also synthesized by one-pot method, Fe3O4-NH2nanoparticles showed more excellent adsorption capacity in spite of their smaller surface area. Batch laboratory techniques were utilized to study the equilibrium of Hg (Ⅱ) adsorption on nanosized Fe3O4-NH2. Equailibration time of the adsorption was estimated as30h at optimized pH of7. The pseudo-second order kinetic model and Langmuir model appeared to be appropriate for describing the equilibrium conditions, and the maximum adsorption capacity reached29.02mg/g. In addition, the adsorption capacity reduced a little after3recycle.(2) Ethylenediamine-modified magnetic chitosan particles (Fe3O4-CS-NH2) were prepared and used for the adsorption of Amaranth and Orang G from aqueous solutions. The Fe3O4-CS-NH2were prepared by adding Fe3O4which were synthesized via coprecipitation to a W/O microemulsion system containing cyclohexane/n-hexanol, chitosan and ferrous salt. This was then modified with ethylenediamine to increase the amine content and to improve the adsorption capacity. Adsorption experiments indicated that the maximum adsorption capacity was determined at a pH of2for Amaranth and a pH of3for Orang G respectively. The both adsorption processes met the pseudo-second-order equation and the Langmuir model. The maximum adsorption capacity reached63.95mg/g (Amaranth) and30.86mg/g (Orange G). We regenerated Fe3O4-CS-NH2with alkaline solution and the regenerated materials can be used to readsorb the dyes.(3) To deal with the defect that the chitosan coating around Fe3O4magnetic core comes off easily, we successfully prepared the quaternized carboxymtheyl chitosan magnetic nanoparticles (QCMC-Fe3O4) by the covalently binding of quaternized carboxymtheyl chitosan (QCMC) onto Fe3O4nanoparticles via carbodiimide activation. The characterization using the transmission electron micrography (TEM), FTIR spectra and Thermogravimetric (TG) showed that the amount of QCMC bound on the Fe3O4nanoparticles was18.8%, and QCMC-Fe3O4particles of20nm possessed good magnetic properties. The adsorption of gram-negative bacteria, Pseudomonas aeruginosa (GIM1.138) which is common in water environment, by the as-prepared sorbents was investigated. The results suggested that QCMC-Fe3O4nanoparticles showed excellent adsorption efficiency, which could be inferred that the large specific surface area and the high surface energy of the nanoparticles cooperated with the hydrophobic interaction played important roles in cell adsorption. |
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