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本文用离子选择电极研究了Ca~(2+)、Na＇和K＇与硅胶表面硅羟基的反应。结果表明:在pH7-10范围内,硅胶表面在Ca(NO_3)_2、NaCl和KCl溶液中分别形成(Si_s-O)_2Ca、Si_s-O Na和Si_s-OK表面配位化合物。求算了配位反应的平衡常数,发现它们随表面配合物浓度增加而减小,并具有相似的表达形式:PK=PK°+alg(l+b{c})。(a、b是与相应金属离子电荷有关的参数,a还与温度t有关,{c}是表面配合物浓度)。求得Ca~(2+)、Na~+和K~+与硅胶表面硅羟基形成表面配合物的PK°依次为:12.0、5.7和5.4,Ca~(2+)的a为(3.9-O.032t),b为200,Na~+和K~+的a为(2.4-0.01t),b为130。
In this paper, the reaction of Ca ~ (2 +), Na ’and K’ with silanols on the surface of silica gel was studied by ion selective electrode. The results showed that (Si_s-O) _2Ca, Si_s-O Na and Si_s-OK surface coordination compounds were formed on the surface of silica gel in Ca (NO_3) _2, NaCl and KCl solutions, respectively. The equilibrium constants for the coordination reaction were calculated and found to decrease as the concentration of the surface complex increased with a similar expression: PK = PK ° + alg (l + b {c}). (a, b are the parameters related to the charge of the corresponding metal ion, a is also related to the temperature t, and {c} is the surface complex concentration). The results showed that the PK ° of Ca ~ (2 +), Na ~ + and K ~ + with the surface silanol groups on the surface of silica gel were 12.0, 5.7 and 5.4, .032t), b is 200, a for Na ~ + and K ~ + is (2.4-0.01t) and b is 130. [