掺杂MnO2的载钙磁性碳纳米管微波再生研究

Study on microwave regeneration of calcium modified magnetic carbon nanotubes doped with MnO2

载钙磁性碳纳米管对腐殖酸具有良好的吸附去除效果,但其微波再生效率有待提高。通过化学沉淀法制备得到掺杂MnO2的载钙磁性碳纳米管复合材料,考察了掺杂MnO2后复合材料吸附腐殖酸的性能,研究了载锰量、微波功率和时间对微波再生效率和材料温度的影响,探讨了再生溶剂量与循环再生次数对再生效果的影响,以及微波再生对材料磁性能的影响。结果表明,随载锰量增大,微波再生效率提高,腐殖酸的吸附去除率稍有下降,但复合材料仍有良好的腐殖酸吸附性能。随微波功率增大,再生效率和材料的表面温度提高。在微波功率600 W、时间10 min、粉体质量浓度100 g/L下,再生率在100%以上。经4次吸附-再生循环后,仍保持良好的吸附、再生性能。掺杂MnO2后复合材料表面温度降低,可保护材料的磁性能。腐殖酸可在微波高温和MnO2的催化氧化作用下分解,复合材料得以再生。

Though the magnetic carbon nanotubes coated calcium enjoy excellent removing effects on the humic acid through adsorption,its microwave regeneration efficiency has to be further improved.In the present paper,the composite of the magnetic carbon nanotubes coated calcium and MnO2 has been prepared by the chemical precipitation method,whose adsorption property has been investigated.The paper is also engaged in the study of the influence of the amount of manganese load,the microwave power and the time length on the microwave regeneration efficiency and material temperature.At the same time,it has also investigated the effects of the amount of solvent in the regeneration and adsorption-regeneration cycle times on the microwave regeneration efficiency,and that of the regeneration on the magnetic property of the composite.Besides,we have also made a discussion over its mechanism of the microwave regeneration.All in all,the results of our investigation indicate that doping MnO2 can help to improve the microwave regeneration efficiency of the magnetic carbon nanotubes coated calcium.With the increase of the amount of loaded manganese,the removal rate of humic acid by adsorption can decrease slightly,though the composite remains still well adsorption of humic acid with its regeneration rate being increased.Moreover,the regeneration efficiency and the temperature of the composite can obviously increase with the microwave power.Its high regeneration rate can be achieved merely with the less amount of solvent.That is to say,the regeneration rate can easily get over 100%at the microwave power of 600 W for 10 min in the composites concentration of 100 g/L,in which the composite concentration and the microwave irradiation time prove to be up to 4 times and 1/3 of the calcium-loaded magnetic carbon nanotubes undoped MnO2,respectively.The excellent adsorption and regeneration performances can still be kept after 4 cycle times of adsorption-regeneration.On the other hand,the temperature of the composite also tends to decrease through doping of MnO2,which can help to protect the magnetism of the composite.What is more,MnO2 doped on magnetic carbon nanotubes increases the temperature promptly,so as to be able to speed up the decomposition of the humic acid by absorbing the microwave radiation under the microwave irradiation.And,simultaneously,MnO2 can also display its function to promote the catalytic oxidation for humic acid.