改性天然含铁锰矿的除汞性能及改性机制研究

Removal performance and mechanism of mercury by modified natural ferromanganese ore

汞是一种有毒金属元素,广泛存在于自然界的水体和土壤环境中。本研究以天然含铁锰矿(FMO)为研究对象,探究水合肼改性天然含铁锰矿(HFMO)的除汞性能及机制。结果表明,FMO主要由纤铁矿、菱锰矿和铁锰复合物等组成,其Fe、Mn含量分别为1.86%、45.61%;HFMO结构中的杂质显著减少,比表面积和孔隙率明显增加。FMO对汞的吸附受水体pH影响大,pH7时Hg(Ⅱ)去除率最高(75.3%);而改性后,HFMO的除汞性能大幅提高,且受pH影响小,在pH3-11范围内,Hg(Ⅱ)去除率稳定在98.2%-94.0%。经Langmuir模型拟合发现,FMO和HFMO对Hg(Ⅱ)的饱和吸附容量分别为12.34、20.46mg·g^(-1)。同时改性HFMO对汞的吸附性能受陪伴离子影响较小。据FTIR、XPS等改性机制表征的数据推测,HFMO表面含有丰富的羟基,Hg(Ⅱ)主要与结构中的Fe-OH和Mn-OH结合。本研究提供了一种高效、低廉的天然含铁锰矿改性方法,对天然含铁锰矿在汞污染修复领域的应用具有重要的指导意义。

Mercury is a toxic metallic element that is widely present in natural water and soil environments.This study focuses on natural ferromanganese ore(FMO)and investigates the mercury removal performance and mechanism of hydrated hydrazine-modified natural ferromanganese ore(HFMO).The results show that FMO is mainly composed of hematite,rhodochrosite,and iron-manganese complexes,with Fe and Mn contents of 1.86%and 45.61%respectively.The impurities in the HFMO structure are significantly reduced,and the specific surface area and pore volume are significantly increased.The adsorption of mercury by FMO is greatly influenced by the pH of the water,with the highest Hg(Ⅱ)removal rate(75.3%)observed at pH 7.However,after modification,HFMO exhibits significantly improved mercury removal performance and is less affected by pH.Within the pH range of 3-11,the removal rate of Hg(Ⅱ)by HFMO remains stable at 98.2%-94.0%.According to the fitting of the Langmuir model,the saturated adsorption capacities of FMO and HFMO for Hg(Ⅱ)are 12.34 and 20.46 mg·g^(-1),respectively.Additionally,the modified HFMO shows litle influence from accompanying ions on its adsorption performance towards mercury.Based on the characterization of modi-fication mechanisms such as FTIR and XPS,it is inferred that HFMO has a rich hydroxyl group on the surface,and Hg(Ⅱ)mainly combines with Fe-OH and Mn-OH in the structure.This study provides an efficient and economical method for modifying natural ferromanganese ore and has important guiding significance for the application of natural ferromanganese ore in mercury pollution remediation.