Chemical Structure of Si–O in Silica Fume from Ferrosilicon Production and Its Reactivity in Alkali Dissolution

Abstract

As an environmentally hazardous waste, silica fume was considered as a potential alternative for cement and SiO 2 production. The structure of Si-O was highly relevant to the reactivity of Si conversion for efficient utilization. In this study, the characteristic and chemical structure of Si-O in silica fume were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR). Deconvolution of XPS and FTIR spectra into elementary profiles was carried out to analyze the structural components. As a result, the valence state, bonding structure and elementary unit in the Si-O network of silica fume were determined. Then, the reactivity silica fume with alkali solution was studied involving the effects of NaOH concentration and temperature. The staged kinetics behavior was associated with the structure of Si-O bonds, and the activation energies were determined. The results thus provided fundamental information for the utilization of silica fume for SiO 2 production and geopolymer.

Fabrication and Characterization of Hydrophobic Cellulose Nanofibrils/Silica Nanocomposites with Hexadecyltrimethoxysilane

“…As shown in Figure 5 e–k, the high-resolution Si2 p spectra of the samples were fitted with three peaks—namely, S1, S2, and S3 at 102.0 ± 0.2, 102.9 ± 0.1, and 103.5 ± 0.1 eV, respectively, which correspond to the Si–C and SiO 2 groups [ 47 , 48 , 49 ]. For Si2 p spectra, the chemical structure was observed with binding energies of 102.9 eV and 103.5 eV corresponding to the Si oxidation states Si3 + and Si4 + , respectively [ 48 , 50 , 51 , 52 ]. As shown in Figure 5 a–d, the HDTMS modification of the CNF/silica nanocomposites resulted in an increase in the C1 peak (284.4 eV) and a significant decrease in the C2 (286.0 eV) and C3 (287.4 eV) peaks for oxygen-containing groups.…”

Effect of Silica Fume on Metakaolin Geopolymers’ Sulfuric Acid Resistance

“…1088 cm −1 (silica fume) represent the Si–O–Si and Si–O–Al bonds [ 67 , 68 ]. The second strong band of the silica fume spectra at 805 cm −1 also represents Si-O-Si bonds of the pozzolan [ 69 , 70 , 71 ]. For metakaolin, the band at 1420 cm −1 can be associated with stretching vibrations of C–O–C bonds resp.…”

Vapor-Phase Molecular Doping in Covalent Organosiloxane Network Thin Films Via a Lewis Acid–Base Interaction for Enhanced Mechanical Properties

“…The Si 2p peak found at 102.38 ± 0.16 eV in the depth ranging from 0 to 220.2 nm (0 to 16th sputtering cycle) is similar to our pristine iCVD PV 3 D 3 (102.32 eV, Figure S2) and the reported Si 2p peak for iCVD PV 3 D 3 (102.50 eV), and it is associated with the VPI-modified siloxane moieties. At the depth of 280.1 nm (17th sputtering cycle), the Si 2p peak splits into dual peaks at 102.39 and 100.07 eV, which corresponds to the native SiO 2 and the Si substrate, respectively, − and indicates the position close to the interface between the hybrid film and the substrate. This interface position also agrees with our film thickness measured using SEM (291 ± 2 nm) and profilometer (300.9 nm, Figure S3).…”