Role of negative charge-assisted hydrogen bonds in adsorption of organic compounds with weak acid groups to humic substances

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K12280
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 64010:Environmental load and risk assessment-related
• Research Institution: Meijo University
• Principal Investigator: Hirotatsu Murano 名城大学, 農学部, 教授 (00570798)
• Co-Investigator(Kenkyū-buntansha): 前林 正弘 名城大学, 農学部, 教授 (00402488)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 溶存有機物 / 凝集 / 超分子凝集体 / 負電荷支援型水素結合 / pKa

Outline of Final Research Achievements

We investigated the flocculation of dissolved organic matter (DOM) and its interaction with small weak acids and investigated the involvement of very strong negative charge-assisted hydrogen bonds (－)CAHB. We found that DOM directed tightly knit primary particles (~10 kDa) to form larger secondary aggregates (up to micrometer in size). The primary particles interacted with (－)CAHB-compatible solutes (simple carboxylic and phosphate) but not with (－)CAHB-incompatible solutes. We confirmed that small organic acids disrupted intra- and intermolecular (－)CAHB in DOM and formed new (－)CAHB with free groups on DOM. The effect was solute concentration-dependent and was more significant at pH 5 than at pH 6, consistent with the CAHB theory.

Free Research Field

土壌化学

Academic Significance and Societal Importance of the Research Achievements

陸域の溶存有機物 (DOM: dissoveld organic matter) は、多くの生物的および非生物的環境反応や水処理において重要な役割を果たしている。そのため、その構造は大きな関心を集めている。我々は、非常に強い負電荷支援型水素結合(－)CAHB が DOM の凝集に寄与し、そのサイズと電荷に影響を与え、弱酸性汚染物質、栄養素、および天然化合物が DOM と相互作用する手段を提供していることを明らかにした。このような相互作用は、環境における DOM の挙動、人為的汚染物質の運命と移動の理解を促進するだけでなく、水処理技術における DOM の役割に寄与する。