An infrared spectroscopic study of sodium silicate adsorption on porous anodic alumina

Abstract

Sodium silicate solutions, also known as 'water-glass', are used for a wide variety of applications. In particular, they are commonly used in pre-treatments of aluminum alloys as cleaners and corrosion inhibitors. Silicate films are known to be promising for corrosion protection and to confer high hydrophilicity. One of the main issues in the study of the formation of silicate films on metal oxides is the complexity of the anionic speciation in aqueous solution. In this work, the mechanism of sodium silicate interaction with porous anodic alumina and its dependence on the solution characteristics is studied by means of Fourier transformed infrared spectroscopy (FTIR). Grazing angle-FTIR and attenuated total reflection-FTIR are used in order to monitor the chemical changes occurring with time on the surface upon silicate adsorption. The effect of the SiO 2 /Na 2 O molar ratio and the temperature is studied. The role of rinsing is investigated when the alumina surface is washed in water after the silicate treatment. A chemical description of the phenomena occurring during silicate treatment is given.

Polymerization of silicate on TiO2 and its influence on arsenate adsorption: An ATR-FTIR study

“…Therefore, the bands at 922 and 1020 cm −1 corresponded to vibrations of the silicate dimer and cyclic oligomer, respectively. The broad peak at 1120 cm −1 was attributed to the silicate polymer on the TiO 2 surface [18,34,35]. The peak assignments are shown in Table 1.…”

Influence of the type of alkali metal cation on the interaction of soluble silicates with porous anodic alumina

“…The aim of the present work is to extend the mechanism of silicate/alumina interaction proposed in previous publications to different types of alkali cations. In particular, the main objective of this work is to understand how the type of alkali metal cation (namely lithium, sodium and potassium) can affect the surface modifications occurring on the oxide layer during immersion in the silicate solution.…”

“…In particular, they are commonly used in pre‐treatments of aluminium alloys as cleaners and corrosion inhibitors. A few studies exist on the interaction of silicates with aluminium oxides . Firment et al .…”

“…The interaction of sodium silicate with porous anodic alumina was extensively investigated in previous publications . In particular, the interaction of soluble sodium silicate (SiO 2 /Na 2 O = 3.5) with porous anodic alumina was studied, and a phenomenological description of this interaction was given . It was found that about 98% of the deposition is absorbed in the pores while 2% of the silicon deposits on the outer surface plateau regions between pores.…”

“…It has also been observed that the anodic oxide layer is strongly attacked at SiO 2 /Na 2 O = 1. The effect of the SiO 2 /Na 2 O molar ratio was therefore included in the formulation of the interaction mechanism . As the cation plays an important role in this interaction, it is important to understand how the type of cation may affect the interaction between silicate and aluminium oxide.…”