K^＋和Na^＋在C3S-纳米SiO2浆体上的存在形式  

Binding Forms of K^+ and Na^+ Ions in C_3S-nano SiO_2 Pastes

作　　者：陆国森 邓敏 莫立武[1] LU Guosen;DENG Min;MO Liwu(Jiangsu National Synergetic Innovation Center for Advanced Materials （SICAM）, Nanjing 210009, China;State Key Laboratory of Materials-Oriented Chemical Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 21009, China)

机构地区：[1]江苏省先进生物与化学制造协同创新中心,江苏南京210009 [2]材料化学工程国家重点实验室,南京工业大学材料科学与工程学院,江苏南京210009

出　　处：《材料科学与工程学报》2017年第6期963-969,共7页Journal of Materials Science and Engineering

基　　金：江苏高校优势学科建设工程资助项目(PAPD);长江学者和创新团队发展计划资助项目(IRT1146)

摘　　要：以拌合液为KOH和NaOH混合溶液的C_3S-纳米SiO_2浆体为对象,研究了液固比对浆体在去离子水中释放K^+和Na^+的影响以及浆体对K^+和Na^+的滞留能力;并采用29Si MAS NMR分析讨论了K^+和Na^+在C_3S-纳米SiO_2浆体上的存在形式。结果表明:随着液固比的增大,浆体释放的K^+和Na^+的百分数逐渐增大;经去离子水充分洗涤后仍有一部分K^+和Na^+存在于浆体中,且浆体对K^+和Na^+的滞留能力随着纳米SiO_2掺量的增加以及拌合液碱浓度的增大而增强。29Si MAS NMR分析证实了K^+和Na^+能够进入C-S-H凝胶层间形成不可逆的化学结合。K^+和Na^+通过取代C-S-H凝胶层间≡SiOCa+中的Ca2+,缩短了C-S-H凝胶中[SiO4]4-四面体链长,从而使凝胶中Q1和Q2峰向左移动。C3S-nanoSiO2 pastes mixed with KOH＋NaOH solutions were prepared.Effect of liquid-tosolid ratio on the release of K^＋and Na^＋ions in the pastes were studied.Meanwhile,the capacities of the pastes on retaining K^＋and Na^＋ions were also investigated.29 Si MAS NMR was employed to do further characterization,and the binding forms of K^＋ and Na^＋ ions in the pastes were discussed.Results showed that the percentages of K^＋and Na^＋ions released by the pastes in de-ionized water increased with the increase of liquid-to-solid ratio.There still remain some K^＋and Na^＋ions in the pastes after washed by de-ionized water.Capacities of the pastes on retaining K^＋ and Na^＋ ions increased as increasing the substitution levels of nanoSiO2 and/or the initial alkali concentrations.K^＋ and Na^＋ ions can enter into the structure of C-S-H gel to replace Ca^2＋ from the silica fraction bound to Ca^2＋,resulting in shortening of the silica chain length,and less negative chemical shifts of Q1 and Q2.This assumption is supported by structural characterization of C-S-H gel using ^29Si MAS NMR.

关 键 词：C3S-纳米SiO2浆体 C-S-H凝胶 K^+和Na^+ 存在形式 

分 类 号：TQ172[化学工程—水泥工业]