Comparative FT-IR study of structural modifications during acid treatment of dioctahedral smectites and hectorite

Utilization of rarasaponin natural surfactant for organo-bentonite preparation: Application for methylene blue removal from aqueous effluent

“…The excess of H + ions in solution will penetrate into raw bentonite surface and then attack the hydroxyl groups in silanol, causing an imbalance positive charge on its surface. The successive of protonation in silicate layer of bentonite can be readily followed by the changes in characteristics of absorption spectra corresponded to vibration of OH groups and octahedral exchangeable cations, leading to the formation of Si-rich phase in bentonite structure [16][17][18]. The protonation of silanol group in raw bentonite produce water molecules (H 2 O) with imbalance positive charge on its surface as indicated in step 2 in Fig.…”

Experimental interactions of Slovak bentonites with metallic iron

“…In contrast, FTIR spectra are the same before and after experiments, which implicitly indicates a process other than dissolution. As we did not identify any changes in FTIR spectra on the basis of Madejová et al (1998) a study, which revealed that the FTIR spectroscopy is able to detect decrease in 10 % of structural Al in SWy-1 montmorillonite after acid treatment, we assumed that structural changes in smectites did not exceed 10 %. L45 bentonite contains Al-Fe 3+ montmorillonite with the highest octahedral Fe 3+ of all samples used for our experiments.…”

Surface Chemistry and Porosity of Natural and Activated Aluminosilicate from Montmorillonite and Clinoptilolite

“…A shoulder appeared at 943 cm -1 in the broad band in the region 900-1100 cm -1 , corresponding to vibrations of Si-OH bonds, which compensate excess of the negative charge of a framework due to a removal of structural Al and a breakup of Si-O-Al bonds [25]. An absorption band at 580 cm -1 is mostly sensitive to presence of residual Al 3+ -ions in octahedral layer, and after sulfuric acid treatment shifts to a higher frequency of 590 cm -1 , which also confirms dealumination of octahedral layers [28]. The formation of the amorphous silica by acid treatment of sorbent is confirmed by appearance of a basic band at 783 cm -1 among three absorption bands of bending vibrations Si-O, which is characteristic to silica gel [29].…”