基于量化计算的生物炭与苯酚弱相互作用机理研究

Study on Mechanism of Weak Interaction Between Biochar and Phenol Based on Quantum Chemical Calculation

芳香族化合物在生物炭表面的分子行为、特别是弱相互作用机制尚不清楚.为揭示生物炭-苯酚间弱相互作用机制,本文采用等温吸附、吸附动力学实验,结合FT-IR表征,应用密度泛函理论(DFT),分析生物炭与苯酚分子间不同吸附构型的结合能、约化密度梯度(RDG)和电子密度拓扑关系.结果表明:等温吸附经72 h达平衡,pH显著影响饱和吸附量,pH=6时吸附量最大;生物炭表面官能团是吸附作用中心,吸附焓(ΔH)始终处于氢键键能范围内;4种吸附构型(A/B/C/D)的弱相互作用均由范德华力和弱氢键共同主导,B构型结合能最低、最稳定,C构型弱相互作用最强,D构型弱相互作用最弱.

The molecular behavior of aromatic compounds on the biochar surface,especially the mechanism of weak interaction,is not yet clear.In order to reveal the mechanism of weak interaction between biochar and phenol,adsorption isotherm and adsorption kinetics experiments,as well as FT-IR characterization were used to analyze the binding energy,reduced density gradient(RDG)and electron density topological relationship between biochar and phenol of different adsorption configurations with density functional theory(DFT).Results showed that the adsorption isotherm reaches the equilibrium after 72h,pH significantly affects the saturated adsorption capacity,and the adsorption capacity is the largest at pH=6.The functional groups on the biochar surface are the adsorption centers.The adsorption enthalpy(ΔH)is always in the range of hydrogen bond energy.The weak interaction of the four adsorption configurations(A/B/C/D)is dominated by van der Waals forces and weak hydrogen bonds.The B configuration has the lowest binding energy and the most stable.The C configuration has the strongest weak interaction,and the D configuration is the weakest.