新型材料磁性氧化锆的除氟效能

采用一步共沉淀法制备了磁铁矿纳米颗粒为核和水合氧化锆为壳的磁性氧化锆材料,研究了其除氟性能.结果表明,磁性氧化锆对氟的Langmuir最大吸附量为35. 46 mg·g~(-1),远高于磁铁矿、活性氧化铝和活性炭.磁性氧化锆对氟的吸附过程较快且吸附动力学数据符合准二级动力学模型,吸附过程为吸热反应.磁性氧化锆对氟的吸附量随pH升高而降低. Cl~-、NO_3~-和SO_4~(2-)的共存对磁性氧化锆除氟没有明显影响,而HCO_3~-和CO_3~(2-)明显抑制氟的吸附.磁性氧化锆吸附的氟可通过1mol·L~(-1)NaOH成功脱附,脱附率99. 5%～99. 6%.脱附后的磁性氧化锆经过再生处理可继续使用.磁性氧化锆对实际井水中的氟的去除效果低于纯水,但适当增加投加量仍可以达到饮用水标准对氟浓度的要求.磁性氧化锆制备简单、使用后可从水中磁分离从而可反复使用,因此是一种有较好应用前景的除氟材料.

Fluoride Removal Efficiency of Novel Material:Magnetite Core/Zirconia Shell Nanocomposite

Magnetite core/zirconia shell nanocomposite (abbreviated as Fe₃O₄@ZrO₂ hereafter) was obtained using one-step co-precipitation method and its performance for removal of fluoride ion from water was studied. The results showed that the Langmuir maximum adsorption capacity of fluoride ion by Fe₃O₄@ZrO₂ was 35.46 mg·g^-1, which was far higher than those of magnetite, activated alumina and activated carbon. Studies of adsorption kinetics indicated that the adsorption of fluoride ion by Fe₃O₄@ZrO₂ was fast and could be well described by the pseudo-second-order model. The adsorption process of fluoride ion was an endothermic reaction. The adsorption of fluoride ion by Fe₃O₄@ZrO₂ decreased with increasing pH. Chloride, nitrate and sulfate anions, which commonly coexist in drinking water, had little effect on F^- adsorption, although the coexistence of HCO₃^- and CO₃^2- reduced the adsorption significantly by increasing the pH of the solution system. The fluoride adsorbed by Fe₃O₄@ZrO₂ could be successfully desorbed with 1 mol·L^-1 NaOH solution as desorption agent. The desorption rate reached 99.5%-99.6%. The F^--desorbed Fe₃O₄@ZrO₂ could be reused for the removal of F^- after regeneration via restoring the protonation status of surface hydroxyl groups on hydrous zirconia. The removal efficiency of fluoride by Fe₃O₄@ZrO₂ from actual well water was lower than that from pure water, but concentration limit for fluoride in drinking water could still be attained by increasing the dosage to a sufficiently high level. Fe₃O₄@ZrO₂ is a promising material for fluoride removal due to its good performance, simple preparation method and easy separation from water by providing an external magnetic field.