为了探讨水化硅酸钙(C-S-H)凝胶对K~+和Na~+的吸附性能,采用3CaO·SiO_2(C3S)和纳米SiO_2制备了不同钙硅物质的量之比(Ca/Si比)的C-S-H凝胶,着重研究浸泡溶液浓度和不同Ca/Si比C-S-H凝胶固体试样加入量对K~+和Na~+吸附能力的影响以及吸附态的K~+和Na~+的解吸行为。结果表明:C-S-H凝胶对K~+和Na~+的吸附能力随着Ca/Si比的降低而增高;对于相同Ca/Si比的C-S-H凝胶,随着浸泡溶液浓度的增大,K~+和Na~+吸附量逐渐增大,随着固体试样用量的增加,K~+和Na~+的吸附量降低而吸附率增高。C-S-H凝胶对K~+和Na~+的吸附不仅与其比表面积有关,而且与溶液中Ca2+浓度(浸泡溶液的p H值有关)有关。在溶液低p H值或高Ca2+浓度体系中,K~+和Na~+的吸附会被溶液中高浓度Ca2+所抑制。脱附实验证实了在碱溶液浓度〈0.5 mol/L时,K~+和Na~+在C-S-H凝胶上吸附是可逆的。
To investigate adsorption of K+ and Na+ by calcium silicate hydrate(C-S-H) gel, C- S-H gels with different n( Ca)/n( Si) were prepared by hydration of 3CaO · SiO2( C3S) incorporated with different substitution levels of nano-SiO2.Effects of alkali solution concentration and solid content on the K+ and Na+ adsorption were studied. Results showed that adsorption capacity of K+ and Na+ increased with the decrease of n (Ca)/n(Si) ratio. For a given n (Ca) /n(Si ) , with the alkali solution concentration and solid content increased, the adsorption capacity of K+ and Na+increased,while the K+ and Na+adsorption content by C- S-H gel decreased with the increase of solid content. K+ and Na+ adsorption capacity of C- S- H gel was affected not only by the specific surface area,but also by the concentration of Ca2+changed by pH value of the solution.At high C^Si ratio or low pH value,alkali adsorption was suppressed by higher Ca2+ concentration. Desorption test demonstrated that adsorption of K+ and Na+ on C- S-H gel was reversible,when the alkali solution concentration was lower than 0. 5 mol/L.