摘要
为明确羟基磷灰石(HAP)的吸附除氟机理以及Al^(3+)对氟吸附的强化作用,开展了羟基磷灰石对水溶液中氟的吸附过程分子模拟。分析了H^(+)-F^(-)-Al^(3+)-H_(2)O体系中氟的存在形态,确定当Al^(3+)存在时,F的主要形态为AlF_(4)^(-)、AlF_(3)、AlF^(2+)、AlF^(2+)、F^(-)。分别选择AlF_(3)、F^(-)、HF为典型的氟形态,分析羟基磷灰石对氟的吸附能、静电势分布、动力学浓度分布以及各原子的部分态密度。研究结果表明:HAP对AlF_(3)、NaF、HF的吸附能依次为-551.23、-466.29、-173.17 kJ/mol,HAP对AlF_(3)、F^(-)、HF都具有较强的吸附能力;Al^(3+)的存在可以改变吸附体系的静电势分布,提供更多的吸附位点和更大的吸附势能,通过P、O位点和H、O位点对F^(-)的吸附以及Al和F之间的强相互作用,提升HAP对F^(-)的吸附稳定性和吸附能力;当动态吸附时,Na^(+)+F^(-)+H_(2)O混合体系中的F^(-)可以快速聚集吸附到HAP的表面,Al^(3+)+F^(-)+H_(2)O混合体系中的F^(-)可以直接进入HAP结构内部并维持较稳定的质量浓度,证明当Al^(3+)存在时,HAP对F^(-)的吸附选择性更强;向吸附质中加入适量的Al^(3+)或者对HAP进行铝负载改性,都有助于强化HAP对氟的吸附能力。
To clarify the adsorption mechanism of hydroxyapatite(HAP)for fluoride removal and the enhancing effect of Al_(3+)on fluoride adsorption,molecular simulations were conducted on the fluoride adsorption process of hydroxyapatite in aqueous solution.The existence forms of fluoride in the H+-F^(-)-Al_(3+)-H_(2)O system were analyzed,determining that in the presence of Al_(3+),AlF^(-)4,AlF_(3),AlF^(2+),AlF^(2+),and F^(-)were the main forms of F.AlF_(3),F^(-),and HF were selected as typical forms of fluoride and the adsorption energy,electrostatic potential distribution,kinetic concentration distribution and partial density of states for each atom were analyzed for hydroxyapatite's interaction with fluoride.The results indicate that the adsorption energies of HAP for AlF_(3),NaF,and HF are-551.23,-466.29,-173.17 kJ/mol,respectively,showing that HAP has good adsorption capabilities for AlF_(3),F^(-),and HF.The presence of Al_(3+)can alter the electrostatic potential distribution of the adsorption system,providing more adsorption sites and greater adsorption potential.The enhanced stability and adsorption capability of HAP for F^(-)can be attributed to the adsorption through P and O sites,as well as the strong interactions between Al and F.During dynamic adsorption,F^(-)in the Na+,F^(-),and H_(2)O mixed system can quickly aggregate and adsorb onto the surface of HAP.F^(-)in the Al_(3+),F^(-),and H_(2)O mixed system can directly enter the interior structure of HAP and maintain a more stable mass concentration,demonstrating that HAP has better adsorption selectivity for F^(-)in the presence of Al_(3+).Adding an appropriate amount of Al_(3+)to the adsorbate or modifying HAP with aluminum loading can help enhance the fluoride adsorption ability of HAP.
作者
姜科
鄂加强
彭艳春
曹喆
JIANG Ke;E Jiaqiang;PENG Yanchun;CAO Zhe(College of Mechanical and Vehicle Engineering,Hunan University,Changsha 410082,China;College of Environmental Engineering,Changsha Environmental Protection College,Changsha 410004,China)
出处
《中南大学学报(自然科学版)》
北大核心
2025年第6期2192-2202,共11页
Journal of Central South University:Science and Technology
基金
湖南省自然科学基金资助项目(2023JJ60254)。
关键词
氟
吸附
强化
铝
静电势
密度泛函计算
fluoride
adsorption
enhancement
aluminum
electrostatic potential
density functional calculation
