不同晶型纳米二氧化锰制备及对亚甲基蓝吸附性能

以高锰酸钾（KMnO₄）为氧化剂、硫酸亚铁铵（NH₄）₂Fe（SO₄）₂]为还原剂,用水热氧化还原反应制备了层状δ-二氧化锰和隧道型α-二氧化锰纳米材料。用X射线衍射（XRD）、扫描电镜（SEM）和氮气吸-脱附技术对产物的晶型、形貌及孔结构进行了表征。实验结果表明,δ-二氧化锰呈花状微球形貌,具有介孔结构（平均孔径为3.4 nm）,BET比表面积为219 m²/g;α-二氧化锰呈纳米线束形貌,具有部分介孔结构（平均孔径为35.7 nm和154.6 nm）,BET比表面积为26 m²/g。研究了不同晶型纳米二氧化锰对亚甲基蓝的吸附性能。实验结果表明,在相同条件下α-二氧化锰的吸附性能优于δ-二氧化锰,且在碱性环境下吸附效果较好。当反应时间达到120 min时,α-二氧化锰和δ-二氧化锰对亚甲基蓝的去除率分别为84.4%和82.9%。

Preparation of manganese dioxide nanomaterials with different crystalline and their adsorption properties to methylene blue

Layered manganese dioxide（δ-MnO₂） and tunneling manganese dioxide（α-MnO₂） nanomaterials were prepared by using hydrothermal oxidation-reduction reaction by using KMnO₄ as oxidant and（NH₄）₂ Fe（SO₄）₂ as reductant.The obta-ined products were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and N₂ adsorption-des-orption technologies in order to investigate their crystalline,morphology and pore structural properties.The above results indi-cate that δ-MnO₂ has flower-like sphere morphology with mesoporous structure（average pore diameter is 3.4 nm）,and its BET specific surface area is 219 m²/g.α-MnO₂ has nanowire bundles shape with partial mesopore structure（average pore di-ameter is 35.7 and 154.6 nm）,and its BET specific surface area is 26 m²/g.In addition,the adsorption properties of methylene blue on different crystalline of manganese dioxide were studied which demonstrate that the adsorption performance of α-MnO₂ was better than that of δ-MnO₂ under the same conditions,and the absorption efficiency was even better in alkaline environ-ment.When the reaction time reached 120 min,the removal rates of α-MnO₂ and δ-MnO₂ toward methylene blue reach to 84.4% and 82.9%,respectively.