Preparation of Water Repellent Layer on Glass Using Hydrophobic Compound Modified Rice Hull Ash Silica

Abstract

In this study water repellent layered glass has been prepared by coating silica (SiO2) combined with a hydrophobic silane compound. SiO2 was extracted from rice hull ash and two silane compounds, namely hexadecyltrimethoxysilane (HDTMS) and trimethylchlorosilane (TMCS) were used. Coating was performed through two deposition techniques, i.e. one step (mono-layer) and layer by layer (LBL, multi-layer). The effect of silane to SiO2 mole ratio, silane type and layer number on the glass characters was evaluated. Characterization included hydrophobicity, transparency, surface roughness and stability of coating. Results showed that increasing the mole ratio of silane to SiO2 and the layer number increased the hydrophobicity of the glass surface. The optimum mole ratio was 5:1 and the significant increase of contact angle occurred at lower mole ratio, but the stability tends to be increased at higher mole ratio. For HDTMS-SiO2 layer, the technique of LBL technique produced a coating with higher hydrophobicity and transparency than single-stage one. The LBL technique produced the highest water contact angle of 103.7° with transmittance of 96%, while for TMCS-SiO2 layer the one stage technique produced hydrophobic layer with higher water contact angle of 108.0° and transparency about 94.52%. The prepared hydrophobic glasses were relatively stable in polar and non-polar solvents, but unstable to ambient conditions.

Preparation and Characterization of Some Sol-Gel Modified Silica Coatings Deposited on Polyvinyl Chloride (PVC) Substrates

“…It was observed that, in most cases, it is a combination of these objectives [1]. Many techniques have been carried out to prepare hybrid coatings including plasma etching [2], layer-by-layer film formation [3], electrospinning [4], chemical vapor deposition (CVD) [5] and the sol-gel process [6]. Compared with the mentioned methods, the sol-gel process is the most used method to produce the hybrid silica coatings because: (a) it allows the control of the product's chemical composition; (b) it is attractive for coating polymers that have melting points between 150 and 300 • C; (c) uniform coatings can easily be fabricated by dipping or spin coating; (d) is low cost and a cost-effectiveness technique and (e) ceramic, glass, metal and polymer substrates can be easily coated [7].…”

Utilization of sodium silica from coal fly ash and trimethylchlorosilane as self-cleaning coating on glass

“…The dried sample was then added with 4 M NaOH solution, then stirred with a magnetic stirrer at 150 rpm for 3 hours on a hotplate at 70°C. Finally, the filtrate and the residue are separated so that the yield is a sodium silicate solution [23].…”

“…Originally, TMCS has a low flash point, and it is reactive with water. To decrease the flashpoint, TMCS should be dissolved in an organic solution [23] [24]. Then, TMCS solution or silane sol is added to natrium silicate solution or silica sol.…”

“…Then, TMCS solution or silane sol is added to natrium silicate solution or silica sol. In a previous study, the various volume ratios produced between sol silica and sol silane are 1:0, 1:1, 1:2, 1:4, 1:8 [23]. Each sample has its own nomenclature as stated in table 1.…”

Effect of Rice Husk Ash on the Physicochemical Properties of Compost

“…This RHA can cause an environmental problem (air pollution) and space limitations. In order to prevent the environmental problem emanating from RHA, many efforts have been made to utilize RHA in the production of silica gel [6], fire bricks [1], the hydrophobic coating on glass [7], activated carbon, soil conditioner, and biofertilizer [8].…”