学术论文

      CSH凝胶对K+和Na+的吸附作用

      Adsorption of K+and Na+by C-S-H gel

      摘要:
      为了探讨水化硅酸钙(CSH)凝胶对K+和Na+的吸附性能,采用3CaO·SiO2( C3S)和纳米SiO2制备了不同钙硅物质的量之比( Ca/Si比)的CSH凝胶,着重研究浸泡溶液浓度和不同Ca/Si比CSH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:CSH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CSH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。 CSH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pH值有关)有关。在溶液低pH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CSH凝胶上吸附是可逆的。
      Abstract:
      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( C3 S) 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 Ca/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.
      Author: LU Guosen DENG Min MO Liwu HUANG Bei
      作者单位: 南京工业大学 材料科学与工程学院 材料化学工程国家重点实验室,江苏 南京,210009
      年,卷(期): 2017, 39(1)
      分类号: TQ172
      在线出版日期: 2017年3月7日
      基金项目: 江苏高校优势学科建设工程;长江学者和创新团队发展计划