Characterization of Magnesium Silicate Hydrate (MSH) Gel Formed by Reacting MgO and Silica Fume

Abstract

Magnesium silicate hydrate (MSH) gel was formed by reacting magnesium oxide (MgO) with silica fume (SF) in distilled water. The MSH was prepared using a MgO/SF molar ratio of 1.0 (40:60 weight ratio). Samples were analyzed during hydration process up to 300 days at room temperature. The MSH characterization has been carried out using a range of analytical techniques. Quantitative analysis was achieved using thermogravimetric analysis (TG/DTG) with a de-convolution technology. The structure of MSH gel was characterized using solid state nuclear magnetic resonance (29Si NMR) and Fourier transform infrared (FT-IR) spectroscopy. Transmission electron microscopy (TEM) was used to investigate MSH microstructure. Compared with natural magnesium silicate hydrate minerals, the structure of MSH gel is highly disordered and generates on the surface of particles, producing a shell structure with cavity. The molecular structure of MSH phase is layered. The results also show that the extent of polymerization of MSH gel is related to the solution pH during hydration.

Bi‐Functional Magnesium Silicate Catalyzed Glucose and Furfural Transformations to Renewable Chemicals

“…The characteristic band of Mg−O stretching vibration appears at 459 cm −1 . Two small bands at 547 cm −1 and 647 cm −1 are attributed to the symmetric stretching vibration of Si−O−Mg in Mg−Si−MTW‐x silicates . Thus, the FT−IR analysis evidences the successful formation of MTW framework and Mg incorporation in the synthesized silicates, which is consistent with the XRD results.…”

Influence of Dry Milling on Phase Transformation of Sepiolite upon Alkali Activation: Implications for Textural, Catalytic and Sorptive Properties

“…Changes visible in the 400–1800 cm −1 range were consistent with the formation of layer-structured magnesium silicate hydrate phase, evidenced by XRD ( Figure 8 b and Figure 9 b). Thus, the most intense Si-O stretching maximum shifted to 1014 cm −1 , accompanied by the appearance of broad shoulders around 880 cm −1 and 680 cm −1 , due to Si–OH vibrations and to libration modes of Mg 3 OH units, respectively, as expected for the evolution of MSH [ 50 , 51 , 52 ].…”

Effect of the MgO/Silica Fume Ratio on the Reaction Process of the MgO–SiO2–H2O System

“…Figure 6 and Figure 7 show the DSC/DTG curves of the MgO/SF pastes. The first endothermic valley (Δ M 1 , ranging from 50–200 °C) corresponds to the weight loss of the PAW of reaction products (mainly products of the M–S–H gel) [3,8]; the second endothermic valley (Δ M 3 , at approximately 400 °C) occurs due to the removal of the hydroxyl from Mg(OH) 2 [4,5,6,7,8]; and, the exothermic effect at approximately 850 °C is associated with the recrystallization of the M–S–H gel [3,12,13,14,15,16]. In addition, Δ M 2 (which is in the range 200–1000 °C) is the weight loss of the CBW from the reaction products (including Mg(OH) 2 , MgCO 3 and M–S–H gel) [3].…”

“…The reaction process for the MgO−SiO 2 −H 2 O system was divided into two stages, as in references [3,14]. First, MgO reacted with water to form Mg(OH) 2 and then reacted with dissolved silica to form M−S−H gel [5].…”

“…Numerous applications have been realized, including usage in thermal insulation material [6], waste sealing material [7], refractory material [8], and soil stabilization [9]. Magnesium silicate hydrate (M–S–H) gel is the typical reaction product formed in the MgO–SiO 2 –H 2 O system [7,8,9,10,11,12,13,14]. Cole [15] found a crystalline M–S–H phase, which was identified as 4MgO·SiO 2 ·8.5H 2 O. Gollop [16] found that M–S–H gel forms in Portland cement pastes by magnesium sulfate attack, and characterized the gel as a poorly crystallized serpentine (3MgO·2SiO 2 ·2H 2 O).…”