The Influence of Organically Modified Derivatives of Silica on the Structure and the Wetting Angle Values of Silica Coatings

The surrounding environment often acts in a destructive way on materials we apply in our everyday life. The best way to protect them against such activity is to cover the basic materials with coatings possessing different properties, tailored to their applications. Anticorrosive layers are one of the biggest groups of such protective coatings, especially those containing silica or its derivatives. Depending on a type of silica precursor and a method of deposition, one can obtain coatings of different structures and properties. In this work, three different silica precursors were applied: TEOS (tetraethylorthosilane), DDS (dimethyldiethoxysilane) and AerosilTM (the powder silica). Sols of different concentrations of the aforementioned precursors as well as commercially available preparations (Sarsil H1 4/2 and SILOXAN W290) were applied for thin films deposition by a dip coating or an infiltration method. The substrates could be divided in two groups: metallic (steel and titanium or titanium alloys) and porous (represented by old brick, sandstone and limestone). Following the deposition process, the layers on metallic substrates were additionally annealed at 500 °C to improve their adhesion and mechanical properties, while those on porous materials were dried in air. All prepared coatings were primarily studied by FTIR spectroscopy and X-ray diffraction. The morphology of their surfaces was imaged by SEM and AFM microscopies, which also allowed determination of the roughness of obtained materials. The measurements of wetting angle values enabled to find the relationship between the surface topography, the type of silica precursor and the hydrophobic/hydrophilic properties of the samples. The results confirmed the hydrophobic properties of coatings obtained by the infiltration technique on the porous materials and the high hydrophilicity of the annealed thin film deposited on the metallic substrates.

Formulating A Novel Fluorinated Silica Nanoparticle using Fluoroalkylsilane as a Wettability Alteration Agent

A novel fluorinated silica nanoparticles were synthesized using 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS17) and further characterized to evaluate the wettability alteration capability. Previous research (1, 2) has utilized fluoroalkanoic acids as the coating agent. First, the in-situ functionalization method employs tetraethoxysilane (TEOS) as the silica precursor and water-soluble amine as the catalyst. It is then further functionalized with 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (FAS17) with ethanol to attain the novel fluorinated silica nanoparticles. The preliminary characterization from FTIR analysis indicated that the in-situ functionalization was successfully applied. The new bonding formation with fluorine attachment on the novel fluorinated silica nanoparticles is capable to alter the wettability of the solid surface, exhibiting self-cleaning properties.

Deconvolution of TEOS/TEVS Xerogel by Single or Dual Organic Catalyst Addition

Currently, xerogel has been applied as a filtration material, especially in membrane desalination. However, the xerogel matrix structure for desalination have to be designed properly in order to allow rejection of salt and obtain good hydro-stability, thus, silica precursor in the form of TEOS (tetraethyl orthosilicate)/TEVS (triethoxy vinyl silane) and organic acid catalyst are suitable material for fabrication. The aim of this study is therefore to fabricate and perform deconvolution of TEOS/TEVS xerogel by adding single or dual catalyst, using FTIR (Fourier-transform Infrared Spectroscopy) and Fityk software. The xerogel was fabricated by dried silica sol and calcined using RTP technique (rapid thermal processing) at 450 °C. Prior to this fabrication, the silica sol was synthesized by sol gel method, using a mixture of silica precursor TEOS/TEVS, ethanol solvent, and varied addition of single catalyst (citric acid) as well as dual catalyst (citric acid + ammonia) for 2 hours, at 50 °C. Subsequently, the xerogel was characterized by FTIR and the deconvolution was obtained through Gaussian approach, with Fityk software. All TEOS/TEVS xerogel samples indicated existence of silanol (Si-OH), siloxane (Si-O-Si) and silica-carbon (Si-C) functional groups. The xerogel deconvolution of TEOS/TEVS using single catalyst exhibit a peak area ratio of Si-OH/Si-O-Si, and this is similar to the dual catalyst counterpart of 0.24 (unit area) and 1.86 (unit area), for Si-C area ratio. This shows the addition of single catalyst was enough to produce deconvolution in TEOS/TEVS xerogel, dominated by siloxane functional group and carbon bonds with the ability to enhance membrane material hydro-stability’s fabrication.

On the Mechanism of Bioinspired Formation of Inorganic Oxides: Structural Evidence of the Electrostatic Nature of the Interaction between a Mononuclear Inorganic Precursor and Lysozyme

Nature has evolved several molecular machineries to promote the formation at physiological conditions of inorganic materials, which would otherwise be formed in extreme conditions. The molecular determinants of this process have been established over the last decade, identifying a strong role of electrostatics in the first steps of the precipitation. However, no conclusive, structure-based evidence has been provided so far. In this manuscript, we test the binding of lysozyme with silica and titania potential precursors. In contrast with the absence of structural information about the interaction with the silica precursor, we observe the interaction with a mononuclear titanium(IV) species, which is found to occur in a region rich of positive charges.

FTIR STUDIES OF THE TEOS/TEVS XEROGEL STRUCTURE USING RAPID THERMAL PROCESSING METHOD

The tetraethyl orthocycate (TEOS) is mainly used as a silica precursor. Silanol content of silica material is the main cause of low hydrostability which led to resulting in poor performance, especially in water treatment. The stronger bond strength formed by incorporating a carbon structure from triethoxy vinyl silane (TEVS). The xerogel fabrication resulted in the composition of TEOS: TEVS: EtOH: HNO3: H2O: NH3 to be 0.9: 0.1: 38: 0.00078: 5: 0.0003. . The purpose is to study the structure of organosilica xerogel calcined at 350oC, 450oC and 600oC in the Fourier-transform infrared (FTIR) using rapid thermal processing. The deconvolution of FTIR spectra calculated using the Fityk software. The result of the best xerogel peak shows at calcination of 450°C with peak area siloxane of 15.39, silanol of 3.32 and silica carbon of 3.85.

Synthesis of KCC-1 Using Rice Husk Ash for Pb Removal from Aqueous Solution and Petrochemical Wastewater

A silica-rich rice husk ash (RHA, 95.44% SiO2) was used as a silica precursor in the synthesis of KCC-1 for Pb(II) removal. The extraction of silica was carried out under several extraction methods (alkali fusion (AF), reflux (RF) and microwave heating (MW)) and extraction parameters (NaOH/RHA mass ratio, fusion temperature and H2O/NaOH-fused RHA mass ratio). The highest silica content was obtained using AF method at extraction conditions of NaOH/RHA mass ratio = 2, fusion temperature = 550 ºC, and H2O/NaOH-fused RHA mass ratio = 4, with silica concentration of 85,490 ppm. TEM, FTIR, and BET analyses revealed the synthesized KCC-1 has fibrous morphology with surface area of 220 m2/g. The synthesized KCC-1 showed good performance in removal of Pb(II) from aqueous solution (74%) and petrochemical wastewater (70%). The analyses of petrochemical wastewater revealed that the adsorption process using synthesized KCC-1 effectively decreased the concentration of COD (489 mg/L to 106 mg/L), BOD (56 mg/L to 34 mg/L) and Pb(II) (22.8 mg/L to 6.71 mg/L). This study affirmed that KCC-1 was successfully synthesized using RHA as silica precursor and applied as an efficient adsorbent for Pb(II) removal. Copyright © 2019 BCREC Group. All rights reservedReceived: 15th November 2018; Revised: 1st January 2019; Accepted: 7th January 2019; Available online: 25th January 2019; Published regularly: April 2019How to Cite: Hasan, R., Chong, C.C., Setiabudi, H.D. (2019). Synthesis of KCC-1 Using Rice Husk Ash for Pb Removal from Aqueous Solution and Petrochemical Wastewater. Bulletin of Chemical Reaction Engineering & Catalysis, 14 (1): 193-201 (doi:10.9767/bcrec.14.1.3619.193-201)Permalink/DOI: https://doi.org/10.9767/bcrec.14.1.3619.193-201