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Engineering of Bioactive Surfaces
Published in Simona Badilescu, Muthukumaran Packirisamy, BioMEMS, 2016
Simona Badilescu, Muthukumaran Packirisamy
Plasma polymer modification is widely used in biomedical applications to improve the biocom-patibility of surfaces. It has been demonstrated that polar groups, formed by plasma-based oxidation on the inner surfaces of microfluidic devices, tend to be covered by hydrophobic material. For this reason, a coating with SiO2 as a barrier material can be used to achieve permanent hydrophilic properties.5 By using a microplasma-based treatment, as shown in Figure 4.3, the inner surfaces of microfluidic components already sealed were successfully functionalized. For the deposition of silicon dioxide coatings, the precursor molecule, i.e., tetramethyl orthosilicate (TMOS), can be used with the feed gas. By using this technique, surfaces with permanent wettability can be easily obtained.
Synthesis, Characterization, and Applications of Silica Spheres
Published in Devrim Balköse, Ana Cristina Faria Ribeiro, A. K. Haghi, Suresh C. Ameta, Tanmoy Chakraborty, Chemical Science and Engineering Technology, 2019
Lavanya Tandon, Poonam Khullar
Silica spheres of different sizes are obtained by varying the size of silica sol droplet in an immiscible liquid before it gels. Silicon esters like tetramethyl orthosilicate (TMOS and TEOS) or a concentrated sodium silicate solution act as silica source. The hydrogel bodies of few mm of silica spheres are obtained and are washed and dried at a low temperature, that is, at 120°C, and then calcined at a high temperature of around 450°C. Another method to obtain silica sphere is through the controlled hydrolysis of silicon esters.74 But the silica sphere prepared by this method have irregular shapes, broad pore size distribution, and relative low specific surface area (30–690 m/g)75and can be prepared in a single step as given in Figure 12.7.
Electromagnetic interference shielding effectiveness of sol-gel coating on Cu-plated fabrics
Published in The Journal of The Textile Institute, 2021
P. V. Kandasaamy, M. Rameshkumar
In this work, Triethoxyvinylsilane (TVS), Triethoxyphenylsilane (TPS), Vinyltrimethoxy-silane (VTMS), Tetramethyl orthosilicate (TMOS) and Tetraethyl orthosilicate (TEOS) were used as precursors. For coating, the sol-gel was synthesized by mixing of precursor, deionized water and solvent (Ethanol) with the molar ratio of 1:4:8 respectively (Periyasamy et al., 2019). Later the mixture was adjusted with the pH of 3 by using of 0.1 M of Nitric acid. The mixture was kept for 8 h at room temperature with air-tight container under stirrer conditions (300 rpm) to ensure the components had sufficient time to react with each other properly. After 8 h, the sol-gel was ready to be applied on the Cu coated fabric. Padding mangle was used for sol-gel coating on the metal coated fabrics. The fabric was padded with 80% expression. Then, the fabric was dried in atmospheric temperature and cured at 130 °C for 5 min.
Green synthesis of SiO2 from Equisetnm arvense plant for synthesis of SiO2/ZIF-8 MOF nanocomposite as photocatalyst
Published in Journal of Coordination Chemistry, 2023
Babak Azari, Afshin Pourahmad, Babak Sadeghi, Masoud Mokhtary
TEOS (tetraethyl orthosilicate)/TMOS (tetramethyl orthosilicate) is used to produce silica powders with extremely high purity [23]. However, their preparations are very expensive, which limits their usage. Silica-rich plant materials such as rice husk [24], wheat hull and wheat hull ash [25], bagasse ash [26], lemon grass [27], etc. can be used as an alternative source to prepare purified silica in an almost amorphous form, considered as a cheap source for the production of various silicon-based materials.
One-pot removal of pharmaceuticals and toxic heavy metals from water using xerogel-immobilized quartz/banana peels-activated carbon
Published in Green Chemistry Letters and Reviews, 2023
Ibrahim Karume, Simon Bbumba, Moses Kigozi, Alice Nabatanzi, Is’harq Z. T. Mukasa, Solomon Yiga
Water purification methods that employ natural adsorbents mostly use sand (silica), gravel and charcoal/activated carbon are not efficient in removing all organic and inorganic wastes. In addition, activated carbon varies greatly depending on the source of raw material to be burnt, which necessitates knowing the composition to fully anticipate and understand the adsorption mechanism and range. In this work banana peels of a variety of Musa species commonly consumed in Central and Western Uganda were burnt to produce the activated carbon. Further, sand and gravel may contain a variety of mineral compositions where leaching of inorganic residues during water filtration may occur causing secondary pollution. Xerogel is a dry silica with (SiO2)n framework similar to the sand (SiO2) replaced sand. In 3-dimension, the xerogel structure has the [SiO4]4- tetrahedra linked by an oxygen atom adopting cages with varying pore sizes which in addition to the high negative charge can act as trap for metal ions and other small molecules. For example, they have been used to immobilize enzymes while retaining biological activity (13). Xerogels are synthesized by the sol-gel method, a quick, cheap, and environmentally process that involves acid-catalyzed hydrolysis of silane to form a sol followed by condensation to form a gel (14). Tetramethyl orthosilicate (TMOS) is the simplest silane used in sol-gel formation (Scheme 1). The negative charge of the oxygen atoms in the xerogel’s (SiO2)n structure and the free hydroxyl groups not condensed during sol formation allow electrostatic attractions, hydrogen bonding and chemical coordination with metals ions and pharmaceuticals. In addition, the porous nature of xerogel can trap particles inside enhancing the adsorption. The proposed adsorption action of the xerogel is shown in Figure 1.