新型多孔生物质铁炭基功能材料高效去除镉及其作用机制

Novel biomass-derived porous iron/carbon materials for highly efficient cadmium removal and its mechanisms

通过高温厌氧碳热还原方法制备出一种新型多孔生物质铁炭基功能材料,并详细分析了材料的结构和性质;考察了制备过程中的热解温度、pH和干扰离子等环境因子对镉吸附性能的影响,并揭示了铁炭基功能材料对镉的固定机制。结果表明,材料比表面积和孔容随热解温度升高而增加,在800℃材料中形成了纳米零价铁和碳化铁,制备出了具有磁性的铁炭基功能材料(MCFe-800),有利于材料的磁性回收。动力学实验结果表明,MCFe-800对水体镉的去除率明显高于其他热解温度,最大吸附容量归一化到铁为463.84 mg·g^(-1)。在偏中性条件下更有利于对镉的去除。MCFe-800对镉的固定机制主要为静电吸附、共沉淀和表面络合。此外,经过4次循环实验后,MCFe-800对实际水体中镉的去除率仍为75.0%。滤柱实验结果表明,当镉初始质量浓度为1000μg·L^(-1)和2000μg·L^(-1)时,有效处理量分别为400 BV和270 BV。因此,新型多孔生物质铁炭基功能材料在水体镉污染修复方面具有很大应用潜力。

In this study,a type of novel biomass-derived porous iron/carbon material was prepared by the hightemperature carbothermal reduction method under anaerobic conditions,and its structure and properties were analyzed in detail.The effects of environmental factors during preparation including pyrolysis temperature,pH,and co-existing ions on the performance of cadmium(Cd) removal were investigated,and the corresponding Cd fixation mechanism by this iron/carbon material was revealed.The results show that the specific surface area and pore volume of the material increased with the increase of the pyrolysis temperature,and nanoscale zerovalent iron and iron carbide occurred at 800℃,a magnetic iron/carbon-based functional material(MCFe-800)was prepared,which was beneficial to the magnetic recovery.The adsorption kinetic experiment results show that the removal efficiency of Cd by MCFe-800 was significantly higher than that of other pyrolysis temperatures,and the maximum removal capacity normalized to iron was 463.84 mg·g^(-1).It is more favorable for Cd removal by MCFe-800 under neutral conditions.The removal mechanisms of Cd were mainly electrostatic adsorption,co-precipitation,and surface complexation.In addition,after four cycles,the removal efficiency of Cd by MCFe-800 in real water was still 75.0%.Filter column experiments show that the treatment capacities of MCFe-800 were 400 BV and 270 BV when the initial concentrations of Cd(II) were 1 000 μg·L^(-1) and 2 000μg·L^(-1),respectively.Therefore,the novel biomass-derived porous iron/carbon material has a great application potential for the remediation of Cd pollution in water.