| 30 | 0 | 129 |
| 下载次数 | 被引频次 | 阅读次数 |
【目的】深入探究纳米孔隙中重金属铅的扩散吸附行为，对于理解气态铅在复杂孔隙结构中的迁移机理及开发铅吸附剂具有重要意义。【方法】本文以无定形SiO2为基底，构建纳米孔道物理模型；运用第一性原理计算手段，对PbO的Lennard-Jones(LJ)力场参数进行拟合；基于Monte Carlo方法，通过自主编程开发气态铅分子在SiO2纳米孔内的径向力场计算模型。在此基础上，结合Oscillator扩散理论与吸附平衡模型，深入揭示温度、孔径及分子性质等因素对气态铅流体扩散系数与吸附平衡常数的影响。【结果】研究表明，气态铅的扩散系数随孔径增大而显著提高，且铅单质(Pb)的扩散能力优于氧化铅(PbO)，这可归因于铅单质(Pb)更低的分子质量与更弱的流-固作用势能。气态铅的吸附平衡常数随孔径增大呈下降趋势：孔径小于1 nm时，吸附作用显著；进入大孔径范围后，平衡常数迅速降至1左右。温度升高对气态铅的扩散起到促进作用，但会削弱铅分子的吸附效果。气态铅分子的传导系数随孔径与温度增大而上升，且在大孔径区域增长速率更快，这源于传导系数与孔径之间存在二次函数形式的依赖关系。低温或小孔径条件下，吸附效应占据主导作用，此时传导系数随孔径或温度增加反而下降。【结论】本文揭示了气态铅在复杂纳米孔隙中的迁移机理并量化关键影响参数，为燃煤烟气重金属污染高效控制及吸附剂优化设计提供了理论依据。
Abstract：[Objective]A thorough understanding of the diffusion and adsorption behaviors of lead(Pb) in nanopores is crucial for elucidating the transport mechanisms of gaseous lead in complex porous structures and developing efficient lead adsorbents. [Methods]In this study, an amorphous silica-based nanopore model was constructed, and the LennardJones(LJ) force field parameters for PbO were fitted using first-principles calculations. A self-developed Monte Carlo algorithm was employed to establish the radial force field of gaseous lead molecules within silica nanopores. Furthermore, Oscillator diffusion theory and adsorption equilibrium models were applied to investigate the effects of temperature, pore size, and molecular properties on fluid diffusivity and adsorption equilibrium constants. [Results]The results indicate that the diffusion coefficient of gaseous lead increases significantly with pore size, with molecule Pb exhibiting higher diffusivity than PbO due to its lower molecular mass and weaker fluid-solid interaction potential. The adsorption equilibrium constant decreases with increasing pore size, showing pronounced adsorption effects in sub-1 nm pores but rapidly approaching unity in larger pores. Elevated temperatures enhance lead diffusion but suppress adsorption. The transport coefficient of gaseous lead increases with both pore size and temperature, exhibiting a quadratic dependence on pore size, leading to a more pronounced enhancement in larger pores. However, under lowtemperature and small-pore conditions, adsorption dominates, causing the transport coefficient to decrease with increasing pore size and temperature. [Conclusion]This study quantitatively elucidates the transport mechanisms of gaseous lead in complex nanoporous structures, providing a theoretical foundation for controlling heavy metal emissions in coal-fired flue gas and designing high-performance adsorbents.
[1]DAI S F, FINKELMAN R B. Coal geology in China:An overview[J]. International Geology Review, 2018, 60(5/6):531-534.
[2]YOU C F, XU X C. Coal combustion and its pollution control in China[J]. Energy, 2010, 35(11):4467-4472.
[3]XU M H, YU D X, YAO H, et al. Coal combustion-generated aerosols:Formation and properties[J]. Proceedings of the Combustion Institute, 2011, 33(1):1681-1697.
[4]MANDAL G C, MANDAL A, CHAKRABORTY A. The toxic effect of lead on human health:A review[J]. Human Biology and Public Health, 2023, 3:1-11.
[5]WANI A L, ARA A, AHMAD USMANI J. Lead toxicity:A review[J]. Interdisciplinary Toxicology, 2015, 8(2):55-64.
[6]NOMURA Y, FUJIWARA K, TERADA A, et al. Prevention of lead leaching from fly ashes by mechanochemical treatment[J]. Waste Management, 2010, 30(7):1290-1295.
[7]WANG N N, SUN X Y, ZHAO Q, et al. Leachability and adverse effects of coal fly ash:A review[J]. Journal of Hazardous Materials,2020, 396:122725.
[8]MIRICIOIU M G, NICULESCU V C. Fly ash, from recycling to potential raw material for mesoporous silica synthesis[J].Nanomaterials, 2020, 10(3):474.
[9]ASTUTI W, CHAFIDZ A, AL-FATESH A S, et al. Removal of lead(Pb(Ⅱ))and zinc(Zn(Ⅱ))from aqueous solution using coal fly ash(CFA)as a dual-sites adsorbent[J]. Chinese Journal of Chemical Engineering, 2021, 34:289-298.
[10]GAYA U I, OTENE E, ABDULLAH A H. Adsorption of aqueous Cd(Ⅱ)and Pb(Ⅱ)on activated carbon nanopores prepared by chemical activation of doum palm shell[J]. SpringerPlus,2015,4(1):458.
[11]XU Y F, TANG H J, LIU L M, et al. Hierarchical Fe/ZSM-5zeolites for efficient Hg0 removal from coal-fired flue gas[J].Chemical Engineering Journal, 2022, 450:138180.
[12]KNUDSEN M. Die gesetze der molekularströmung und der inneren reibungsströmung der gase durch röhren[J]. Annalen der Physik, 1909, 333(1):75-130.
[13]SMOLUCHOWSKI M V. Zur kinetischen Theorie der transpiration und diffusion verdünnter gase[J]. Annalen der Physik,1910,338(16):1559-1570.
[14]HU C X, BHATIA S K. Multicomponent transport in nanoporous networks:Theory and simulation[J]. Chemical Engineering Journal, 2018, 346:748-761.
[15]BHATIA S K. Modeling pure gas permeation in nanoporous materials and membranes[J]. Langmuir, 2010, 26(11):8373-8385.
[16]BHATIA S K, BONILLA M R, NICHOLSON D. Molecular transport in nanopores:A theoretical perspective[J]. Physical Chemistry Chemical Physics, 2011, 13(34):15350-15383.
[17]JEPPS O G, BHATIA S K, SEARLES D J. Wall mediated transport in confined spaces:Exact theory for low density[J].Physical Review Letters, 2003, 91(12):126102.
[18]BHATIA S K, JEPPS O, NICHOLSON D. Tractable molecular theory of transport of Lennard-Jones fluids in nanopores[J]. The Journal of Chemical Physics, 2004, 120(9):4472-4485.
[19]BONILLA M R, BHATIA S K. The low-density diffusion coefficient of soft-sphere fluids in nanopores:Accurate correlations from exact theory and criteria for applicability of the Knudsen model[J]. Journal of Membrane Science, 2011, 382(1/2):339-349.
[20]ZHANG X R, WANG W C, JIANG G F. A potential model for interaction between the Lennard-Jones cylindrical wall and fluid molecules[J]. Fluid Phase Equilibria, 2004, 218(2):239-246.
[21]SHEN A, YIN L H, DUAN J L, et al. Vapor nucleation in presence of nanoparticles revealed by molecular dynamics simulations[J].International Journal of Thermal Sciences, 2025, 218:110174.
[22]YANG X N, YUE X P. Adsorption and structure of Lennard–Jones model fluid in slit-like amorphous silica nanopores[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects, 2007, 301(1/2/3):166-173.
[23]MAGHFIROH C Y, ARKUNDATO A, MISTO, et al. Parameters(σ, ε)of lennard-Jones for Fe, Ni, Pb for potential and Cr based on melting point values using the molecular dynamics method of the lammps program[J]. Journal of Physics:Conference Series,2020, 1491(1):012022.
[24]SHEN A,ZULUAGA-BEDOYA C C, BHATIA S K. Molecular modeling of gaseous mercury species adsorption and transport in nanoporous silica membranes[J]. Fuel, 2023, 351:128914.
基本信息:
DOI：10.19944/j.eptep.1674-8069.2026.03.004
中图分类号:X773
引用信息:
[1]王明骏,申奥,胡海韬.二氧化硅纳米孔隙中重金属铅的迁移机理研究[J].电力科技与环保,2026,42(03):383-389.DOI:10.19944/j.eptep.1674-8069.2026.03.004.
基金信息:
广东省极端条件重点实验室资助项目（2025JDTJYB008）
2025-04-15
2025
2025-11-04
2025-10-30
2025
1
2026-06-15
2026-06-15