从电子结构到环境修复：离子化草甘膦在羧基修饰碳纳米管上的吸附

中文摘要 AI 辅助

草甘膦是一种广泛使用的除草剂，其在水生和陆地环境中的持久性与毒性需要高效的去除策略。本研究采用GFN2 xTB计算结合隐式ALPB水溶剂化模型与自动对接技术，探究了5种pH依赖型离子化草甘膦形式（G1-G5）在羧基共价修饰（覆盖率0-25%）的(10,0)单壁碳纳米管上的吸附行为。吸附能呈现出明确的电荷依赖趋势：二价阴离子形式（G4）和三价阴离子形式（G5）在整个功能化范围内表现出最负的结合能，而质子化及中性形式（G1、G2）吸附较弱，在高COOH含量下趋近于可逆吸附。去质子化形式G5的结合能从原始碳纳米管（CNT）的-2.17 eV增强至羧基覆盖率10%和25%时的约-5.7 eV，在羧基覆盖率15-20%附近因相邻基团的空间位阻和静电拥挤出现局部极小值。溶剂化自由能分解显示，主要稳定作用来自静电相互作用，且随羧基密度增加，氢键贡献逐渐增大。所有复合物的HOMO-LUMO能隙极小（0.02-0.22 eV），表明其对吸附及功能化具有高电子敏感性。总体而言，CNT+COOH体系可根据草甘膦的离子化状态在强捕获与可再生两种状态间切换，为pH响应型环境修复提供了可调平台。

英文摘要

Glyphosate is a widely used herbicide whose persistence and toxicity in aquatic and terrestrial environments demand efficient removal strategies. Here we employ GFN2 xTB calculations with implicit ALPB aqueous solvation and automated docking to investigate the adsorption of all five pH dependent ionized forms of glyphosate (G1-G5) on (10,0) single walled carbon nanotubes covalently functionalized with carboxyl groups at 0-25% coverage. Adsorption energies reveal a clear charge dependent trend: the dianionic (G4) and trianionic (G5) species exhibit the most negative binding energies over the entire functionalization range, while the protonated and neutral forms (G1, G2) bind weakly, approaching reversible adsorption at high COOH contents. The deprotonated form G5 strengthens from -2.17 eV on pristine CNT to about -5.7 eV at 10% and 25% functionalization, with a local minimum near 15-20% COOH due to steric and electrostatic crowding of adjacent groups. Decomposition of the solvation free energy shows dominant electrostatic stabilization complemented by increasingly favorable hydrogen bond contributions as carboxyl density grows. All complexes display very small HOMO-LUMO gaps (0.02-0.22 eV), indicating high electronic sensitivity to adsorption and functionalization. Overall, CNT+COOH systems can operate in both strong capture and regenerable regimes depending on glyphosate ionization state, offering a tunable platform for pH responsive remediation.

发表机构

• Universidade Federal de Alfenas - UNIFAL-MG（阿尔芬纳斯联邦大学）

机构由 AI 辅助整理，请以论文原文为准。