Abstract
The deposition of zeolites on solid support materials is possible by means of electrochemical methods, impregnation processes, as well as in-situ syntheses. Electrochemical deposition of zeolites has been reported as well, however with readily synthesized zeolite structures. Adhesive deposition of zeolites on stainless steel (S316) has been reported. This report investigates the feasibility of the deposition of silicates by in-situ hydroelectrothermal means. The investigation was done in aqueous solutions of pH = 7 to 13 at different temperatures (25°C to 70°C) by linear sweep method. Deposition was done at a saturated H2 atmosphere to ensure prior deposition of thin iron oxide film on the surface and formation of Fe-O-Si-linkages. This was proven by Raman measurement of the samples. Further linear sweep experiments in the presence of silica show monodentate and bidentate Fe-O-Si linkages on the surface, proven by IR-measurements. Presence of dissolved silica was done by UV-Vis with the molybdate yellow method. The best results are achieved at 70°C at pH 13 and ﹣4 mV (vs Ag/AgCl) or 200 mV (vs SHE). Discontinuous homogeneous layers are found on the stainless steel surface observed by SEM, EDX measurements and electrochemical measurements. Layer discontinuties are caused due to low silica concentration at equilibrium hydrothermal conditions, especially in the absence of silicic acid. All results shown are for the best results achieved except for linear sweep measurements and solubility constants of dissolved silica.
Highlights
Zeolites have been known for their application in heterogeneous catalysis and adsorption purposes [1]
The solubility of silica increases to values of 10−2 mol/dm3, corresponding to 0.6 g/dm3 and provides better distinction of silica deposition on stainless steel
Hydroelectrothermal deposition of silicate layers has been proven in this investigation
Summary
Zeolites have been known for their application in heterogeneous catalysis and adsorption purposes [1]. Their adhesion on structured catalytic packings (KATAPAK®) [2] and deposition on electrodes have been proven to. How to cite this paper: Tamahrajah, J. and Brehm, A. (2015) In-Situ Hydroelectrothermal Deposition of Silicate Layers on Stainless Steel Surfaces. Advances in Materials Physics and Chemistry, 5, 374-382. Brehm have advantages in their respective fields [1]. The deposition with good adhesion must be guaranteed. The good adhesion achieved in the literature cited above has proven to have a science of its own
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