MCM-41负载磁铁矿纳米颗粒及其对Cu(Ⅱ)的吸附特征

Preparation of the MCM-41 supported magnetite nanoparticles and their adsorption characteristics on Cu(Ⅱ)

本研究通过共沉淀法制备了MCM-41负载磁铁矿纳米颗粒(MCM-41/Mag),并研究了其结构、热稳定性及对Cu(Ⅱ)的吸附特征。MCM-41/Mag中磁铁矿纳米颗粒分布在MCM-41的外表面及介孔孔道内,w(磁铁矿)为17.33%的负载型样品(MCM-41/Mag_(0.3))的比表面积为631.6 m^(2)/g,远高于纯磁铁矿纳米颗粒(Mag-NPS)的91.1 m^(2)/g,这归因于磁铁矿纳米颗粒在MCM-41上良好的分散性及载体巨大的比表面积。DSC结果表明MCM-41/Mag_(0.3)中磁铁矿的相变温度显著高于Mag-NPS。MCM-41/Mag_(0.3)吸附Cu(Ⅱ)在120 min可达到平衡,其吸附等温线符合Sips模型,最大吸附量为10.44 mg/g,吸附机理包括化学吸附和物理吸附,部分Cu(Ⅱ)可与磁铁矿表面形成Fe—O—Cu共价键,部分Cu(Ⅱ)通过静电作用吸附在样品表面。MCM-41/Mag_(0.3)中单位磁铁矿对Cu(Ⅱ)的最大吸附量可达62.78 mg/g,显著高于文献报道的其他铁(氢)氧化物。由于其快的吸附速率和高的吸附能力,MCM-41/Mag_(0.3)可作为Cu(Ⅱ)吸附材料用于水体中重金属离子的去除。本研究结果有助于拓展磁铁矿在环境治理领域的应用并为开发性能良好的重金属吸附剂提供理论参考。

The MCM-41 supported magnetite nanoparticles(MCM-41/Mag)were prepared by using the co-precipitation method.The structure,thermal stability,and Cu(Ⅱ)adsorption characteristics of the MCM-41/Mag have been investigated in this paper.Magnetite nanoparticles in the MCM-41/Mag are distributed on the outer surface and in the mesoporous mesopore channels of the MCM-41.The supported sample containing 17.33%magnetite(MCM-41/Mag_(0.3))has a specific surface area of 631.6 m^(2)/g,which is much higher than that(91.1 m^(2)/g)of the pure magnetite nanoparticles(Mag-NPS).This result was attributed to the good dispersion of magnetite nanoparticles on the MCM-41 and the large specific surface area of the supporter(MCM-41).The DSC results show that the phase transition temperature of magnetite in the MCM-41/Mag_(0.3) is obviously higher than that of the Mag-MPS.The adsorption of Cu(Ⅱ)by the MCM-41/Mag_(0.3) can reach equilibrium at 120 min,with the adsorption isotherm of MCM-41/Mag_(0.3) fitting well with the Sips model,and a maximum adsorption amount of 10.44 mg/g.The adsorption mechanisms include chemisorption and physical adsorption.Part of Cu(Ⅱ)could be adsorbed on magnetite nanoparticle surface by the Fe—O—Cu bond,and part of Cu(Ⅱ)was adsorbed on the sample surface by the electrostatic attraction.The maximum adsorption of Cu(Ⅱ)by unit magnetite in the MCM-41/Mag_(0.3) was 62.78 mg/g,which is significantly higher than those of other Fe(hydro)oxides reported in the literature.Due to the fast adsorption rate and high adsorption capacity,the MCM-41/Mag_(0.3) can be used as an adsorbent for removing heavy metal ions from water.The results of this study are helpful to expand the application of magnetite in the field of environmental treatment and could provide a theoretical reference for the development of new heavy metal adsorbents with good adsorption performance.