| Intrinsic Surface Reaction Constant in 1-pK Model of Mg-Fe Hydrotalcite-like Compounds |
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| 作者姓名： | 侯万国 韩书华 李东祥 张高勇 |
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| 作者单位： | [1]KeyLaboratoryofColloidandInterfaceChemistry(ShandongUniversity),MinistryofEducation,Jinan,Shandong250100,China [2]ChinaResearchInstituteofDailyChemicalIndustry,Taiyuan,Shanxi030001,China |
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| 基金项目： | Project supported by the National Natural Science Foundation of China (No. 20273041) and State Education Ministry. |
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| 摘 要： | The relationship among intrinsic surface reaction constant (K) in 1-pK model, point of zero net charge (PZNC) and structural charge density (σst) for amphoteric solid with structural charges was established in order to investigate the effect of σst on pK. The theoretical analysis based on 1-pK model indicates that the independent PZNC of electrolyte concentration (c) exists for amphoteric solid with structural charges. A common intersection point (CIP) should appear on the acid-base titration curves at different c, and the pH at the CIP is pHPZNC. The pK can be expressed as pK=-pHPZNC log(1 2αPZNC)/(1-2αPZNC)], where αPZNC≡σst/eNANs, in which e is the elementary charge, NA the Avogadro‘s constant and Ns the total density of surface sites. For solids without structural charges, pK=-pHPZNC. The pK values of hydrotalcite-like compounds (HTlc) with general formula of Mg1-xFex(OH)2](Cl,OH)x were evaluated. With increasing x, the pK increases, which can be explained based on the affinity of metal cations for H^- or OH^- and the electrostatic interaction between charging surface and H^- or OH^-.
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| 关 键 词： | 镁-铁 水滑石 表面配位作用 双电荷层 零电荷点 |
Intrinsic Surface Reaction Constant in 1-pK Model of Mg-Fe Hydrotalcite-like Compounds |
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| HOU,Wan-Guo,a HAN,Shu-Huaa LI,Dong-Xianga ZHANG,Gao-Yonga,b a Key Laboratory of Colloid and Interface Chemistry.Intrinsic Surface Reaction Constant in 1-pK Model of Mg-Fe Hydrotalcite-like Compounds[J].Chinese Journal of Chemistry,2004,22(3):268-270. |
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| Authors: | HOU Wan-Guo a HAN Shu-Huaa LI Dong-Xianga ZHANG Gao-Yonga b a Key Laboratory of Colloid and Interface Chemistry |
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| Institution: | Shandong University |
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| Abstract: | The relationship among intrinsic surface reaction constant (K) in 1‐pK model, point of zero net charge (PZNC) and structural charge density (σst) for amphoteric solid with structural charges was established in order to investigate the effect of σst on pK. The theoretical analysis based on 1‐pK model indicates that the independent PZNC of electrolyte concenmtion (c) exists for amphoteric solid with structural charges. A common intersection point (CIP) should appear on the acid‐base titration curves at different c. and the pH at the CIP is pHPZNC. The pK can be expressed as pK=‐pHPZNC+log(l+2αPZNC)/(1–2αPZNC)], where α‐PZNC σ/eNANs, in which e is the elementary charge, Na the Avogadro's constant and NS the total density of surface sites. For solids without structural charges, pK=‐ pHPZNC. The pK values of hydrotalcite‐like compounds (HTlc) with general formula of Mg1‐x Fex(OH)2](Cl, OH)x were evaluated. With increasing x. the pK increases, which can be explained based on the affinity of metal cations for H? or OH? and the electrostatic interaction between charging surface and H? or OH?. |
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| Keywords: | surface complexation electric double layer points of zero charge acid-base chemistry structurally charged material |
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