粒状纳米零价铁/炭的制备及对孔雀绿的降解机理

Removal of malachite green from wastewater by zero-valent iron nanoparticles supported on activated carbon powder

以活性炭粉末(PAC)为载体,在负载纳米零价铁(nZVI)后,利用高岭土作为黏合剂,制备了1 cm大小的粒状纳米零价铁/炭颗粒(nZVI/PAC),对制备条件进行了优化,并采用X射线衍射(XRD)、透射电子显微镜(TEM)、氮吸附/脱附、热重法(TG)对合成对材料进行了表征,,模拟了其对典型染料孔雀石绿(MG)的去除研究。结果表明,制备的nZVI/PAC材料对nZVI具有较好的分散性,且提高了nZVI的抗氧化能力。在投加10 g·L^(−1)的nZVI/PAC反应体系中,对含有0.1 g·L^(−1)的MG废水的去除率达到99.5%。MG的去除率随着pH的降低而升高,而升温也有利于MG的去除。MG的去除符合准二级反应动力学模型,nZVI/PAC对MG的去除机理主要是破坏了MG的发色基团和共轭结构,使MG染料脱色并从溶液中去除。且该材料浸水后抗压强度可达1.241 MPa,适用于实际工程应用。

Powder activated carbon(PAC)supported nanoscale zero valent iron composites(nZVI/PAC)were synthesized.Subsequently,granular nZVI/PAC(1 cm)materials were prepared using kaolin clay for sintering and granulation.The optimized conditions for synthesis of granular nZVI/PAC were tested.The resultant materials using X-ray diffraction(XRD),transmission electron microscopy(TEM),nitrogen adsorption/desorption,thermogravimetry(TG).In addition,experiments were carried to investigate removal of malachite green(MG)by the materials.The results showed that the prepared granular nZVI/PAC materials had better dispersion of nZVI and improved the antioxidant capacity of nZVI.The removal rate of MG at concentration of 0.1 g·L^(−1) reached 99.5%with nZVI/PAC of 10 g·L^(−1).It also found that the removal rate of MG increased with the decrease of pH,in contrast,the removal rate of MG was enhanced as the temperature increased.MG removal was consistent with a quasi-secondary reaction kinetic model.The mechanism of MG removal by nZVI/PAC is mainly the destruction of MG chromophores and conjugate structures,resulting in MG dye decolorization and removal from the solution.The material has a compressive strength of 1.241 MPa after immersion in water and is suitable for practical engineering applications.