Hiemstra T, Venema P, Riemsdijk WHV
Department of Soil Science and Plant Nutrition, Wageningen Agricultural University, Wageningen, NL 6700 EC, The Netherlands
J Colloid Interface Sci. 1996 Dec 25;184(2):680-92. doi: 10.1006/jcis.1996.0666.
The proton affinity of individual surface groups has been calculated with a redefined version of the multi site complexation (MUSIC) model. In the new approach the proton affinity of an oxygen originates from the undersaturation of the oxygen valence. The factors valence and coordination number, which are the basis of Pauling's definition of bond valence, in combination with the number of coordinating (Me and H) ions, are dominant in determining the proton affinity. The neutralization of an oxygen by Me ion(s) is calculated on the basis of the actual bond valence, which accounts for structural details, resulting from an asymmetrical distribution of charge in the coordination environment. An important role in the new version of the MUSIC model is given to the H bonds. The model shows that the proton affinity is determined not only by the number of donating H bonds but also by the number of accepting H bonds. The proton affinity of surface groups and of solution complexes can be understood in one theoretical framework, on the basis of a different number of donating and accepting H bonds. The MUSIC model predicts the variation in proton affinity constants for surface groups in particular those with the same number of coordinating Me ions but with a different structural position. The model is able to predict on the basis of the proton affinity of the individual groups the correct PZC of Me hydroxides, oxohydroxides, and oxides, and explains previous exceptions. The model can also be applied in general to other minerals.
已使用重新定义的多位点络合（MUSIC）模型计算了单个表面基团的质子亲和力。在新方法中，氧的质子亲和力源于氧价的不饱和状态。化合价和配位数这两个因素，它们是鲍林键价定义的基础，与配位（Me和H）离子的数量相结合，在决定质子亲和力方面起主导作用。Me离子对氧的中和作用是根据实际键价计算的，该键价考虑了由于配位环境中电荷不对称分布而产生的结构细节。氢键在新版MUSIC模型中起着重要作用。该模型表明，质子亲和力不仅取决于供体氢键的数量，还取决于受体氢键的数量。基于供体和受体氢键数量的不同，可以在一个理论框架内理解表面基团和溶液络合物的质子亲和力。MUSIC模型预测了表面基团质子亲和常数的变化，特别是那些具有相同数量配位Me离子但结构位置不同的表面基团。该模型能够根据各个基团的质子亲和力预测Me氢氧化物、羟基氧化物和氧化物的正确零电荷点，并解释先前的异常情况。该模型通常也可应用于其他矿物。
