Use of infrared spectroscopy to study geopolymerization of heterogeneous amorphous aluminosificates
Use of infrared spectroscopy to study geopolymerization of heterogeneous amorphous aluminosificates
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DOI：
10.1021/la026127e
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发表时间：
2003-10-14
期刊：
影响因子：
3.9
通讯作者：
van Deventer, JSJ
中科院分区：
文献类型：
--
作者：
Lee, WKW;van Deventer, JSJ
地质聚合是描述铝硅酸盐与碱性水溶液反应以产生称为地质聚合物的新型无机粘合剂的所有化学过程的通用术语。在目前的工作中，一个新的分析程序开发研究地质聚合的无定形铝硅酸盐在真实的时间。该程序涉及首先进行一系列精心设计的浸出实验，其中铝硅酸盐用不同碱度和可溶性硅酸盐剂量的碱性水溶液进行碱活化。使用配备有光学发射光谱（ICP-OES）的电感耦合等离子体稀释和分析浸出溶液，并且分离、洗涤、干燥活化的固体颗粒，并通过傅里叶变换红外（FTIR）光谱分析。通过比较从ICP-OES和FTIR分析获得的结果，可以构建线性校准曲线以关联固体的碱活化程度和其T-O-Si（T = Al和Si）不对称伸缩振动频率。使用该校准曲线作为基础，然后可以借助于IR光谱解卷积在真实的时间中近似地质聚合物内感兴趣的铝硅酸盐的碱活化程度。这种新的分析方法可用于研究碱金属和可溶性硅酸盐在碱活化和地质聚合的高度异质性和无定形铝硅酸盐，如粉煤灰的作用。它还可以用来理解地质聚合的反应机理，并确定反应条件（如活化溶液的SiO2/R2 O比，其中R = Na或K），这些条件在控制各种反应途径中至关重要，而这些反应途径又会影响形成的产品和产品的宏观（压缩）强度。
Geopolymerization is a general term to describe all the chemical processes that are involved in reacting aluminosilicates with aqueous alkaline solutions to produce a new class of inorganic binders called geopolymers. In the present work, a novel analytical procedure is developed to study geopolymerization of amorphous aluminosilicates in real time. This procedure involves first conducting a series of well-designed leaching experiments, within which an aluminosilicate is alkali-activated with aqueous alkaline solutions of varying alkalinities and soluble silicate dosages. The leached solutions are diluted and analyzed using inductively coupled plasma equipped with optical emission spectroscopy (ICP-OES), and the activated solid particles are separated, washed, desiccated, and analyzed by Fourier transform infrared (FTIR) spectroscopy. By comparing the results obtained from the ICP-OES and the FTIR analyses, a linear calibration curve can be constructed to correlate the extent of the alkali-activation of the solid and its T-O-Si (T = Al and Si) asymmetric stretching vibration frequency. Using this calibration curve as a basis, the extent of alkali-activation of the aluminosilicate of interest within a geopolymer can then be approximated in real time with the aid of IR spectral deconvolution. This novel analytical procedure can be used to study the roles of alkalis and soluble silicates in alkali-activation and geopolymerization of a highly heterogeneous and amorphous aluminosilicate such as fly ash. It can also be used to understand the reaction mechanism of geopolymerization and to determine the reaction conditions (such as the SiO2/R2O ratio of the activating solution, where R = Na or K) that are critical in controlling the various reaction pathways, which in turn affect the products formed and the macroscopic (compressive) strengths of the products.