HUSCAP logo Hokkaido Univ. logo

Hokkaido University Collection of Scholarly and Academic Papers >
農学院・農学研究院  >
雑誌発表論文等  >

Predictive model of cationic surfactant binding to humic substances



タイトル: Predictive model of cationic surfactant binding to humic substances
著者: Ishiguro, Munehide 著作を一覧する
Koopal, Luuk K. 著作を一覧する
キーワード: NICA model
Donnan model
Langmuir–Freundlich equation
Hill equation
Surfactant binding model
Electrostatic interactions
Specific interactions
Hydrophobic interactions
Humic acid
Fulvic acid
Dodecyl pyridinium chloride
Hexadecyl pyridinium chloride
発行日: 2011年 4月
出版者: Elsevier
誌名: Colloids and Surfaces A: Physicochemical and Engineering Aspects
巻: 379
号: 1-3
開始ページ: 70
終了ページ: 78
出版社 DOI: 10.1016/j.colsurfa.2010.11.075
抄録: Abstract: The humic substances (HS) have a high reactivity with other components in the natural environment. An important factor for the reactivity of HS is their negative charge. Cationic surfactants bind strongly to HS by electrostatic and specific interaction. Therefore, a surfactant binding model is developed that takes both the specific and electrostatic interactions explicitly into account. The model is analogous to that of ion binding to HS with the NICA-Donnan model, but competition for the binding sites is not taken into account and the NICA-Donnan model reduces to the Langmuir–Freundlich–Hill–Donnan (LFH-D) model. The parameters of the LFH equation are the maximum binding, the affinity constant and the non-ideality constant. The non-ideality parameter accounts for both the site heterogeneity and the cooperativity due to hydrophobic interaction between surfactant molecules. The affinity constant incorporates the specific (e.g., hydrophobic) interactions between surfactant and HS. The Donnan part of the model accounts in a simple way for the electrostatic interactions by assuming that for a given set of conditions there is only one electrostatic potential that governs the behavior in the Donnan phase. The separation between the specific interactions (LHF) and the electrostatic interactions (D) is based on the so-called master curve (MC) procedure in which the binding is replotted as a function of the “free” surfactant concentration in the Donnan phase. The MC depends only on the specific interactions. Once the MC is obtained it can be fitted to the LFH equation to obtain the model parameters. Subsequently, the surfactant isotherms can be calculated with the LFH-D model. The model is tested using previously obtained data on dodecyl pyridinium chloride (DPC) and cetyl pyridinium chloride (CPC) binding to some purified humic and fulvic acids at pH about 5. The LFH-D model is well suited to describe the surfactant binding to HAs from very low concentrations up to the iso-electric point (IEP). The affinity of DPC for the different HAs allows ranking of the HAs according to their hydrophobicity. Prediction of DPC binding at other pH values also leads to good results for HA. For FAs the model can only describe the surfactant binding up to an adsorbed amount of 0.5 mol/kg. For higher binding values the LFH-D model underestimates the binding.
Rights: Copyright © 2010 Elsevier B.V. All rights reserved., © <2010>. This manuscript version is made available under the CC-BY-NC-ND 4.0 license
資料タイプ: article (author version)
出現コレクション:雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

提供者: 石黒 宗秀


本サイトに関するご意見・お問い合わせは repo at へお願いします。 - 北海道大学