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Cement-Based Composites with PCMs and Nanoinclusions for Thermal Storage
Published in Antonella D’Alessandro, Annibale Luigi Materazzi, Filippo Ubertini, Nanotechnology in Cement-Based Construction, 2020
Vermiculite is a hydrous silicate mineral (classified as a phyllosilicate) with a porous structure, nontoxic, and light (used in many commercial applications such as construction, thermal acoustic insulation, and agriculture). Perlite is a glassy amorphous volcanic rock with high porosity, a large surface area, very low density, high fire resistance, and low moisture retention. Sepiolite is an important natural clay material with a characteristic fibrous and tubular channel structure. The structural formula of sepiolite is [(OH2)4Mg8(OH)4Si12O30]8H2O, which is responsible for its chemical and physical characteristics related to porosity and surface area [32]. Diatomite (or diatomaceous earth) is composed of fossil remains of diatoms, which are single-celled algae with silica cell walls with different shapes. It has low density, high porosity and purity, rigidity, and inertness [50]. An example of the chemical composition of some of these materials is shown in Table 12.2, as reported by Sari et al. [50].
Surface Activation and Modification
Published in Benny K.G. Theng, Clay Mineral Catalysis of Organic Reactions, 2018
The rate of acid dissolution is influenced by the octahedral sheet composition, crystallinity, and particle size of the clay mineral sample, the type and concentration of acid as well as the duration and temperature of acid treatment. As such, clay minerals vary in their resistance and stability to acid attack. Irrespective of mineral species, however, the final product of acid activation consists of a mixture of unaltered layers and a protonated, hydrated silica phase of short-range order, arising from the decomposition of the tetrahedral sheet (Komadel 2016) (cf. Figure 4.1). This is the case with both 1:1 type layer silicates such as kaolinite, halloysite, and chrysotile (Aglietti et al. 1988; Wypych et al. 2005; Panda et al. 2010; Zhang et al. 2012; Rozalen and Huertas 2013) and 2:1 type phyllosilicates such as smectites and vermiculites (Fahn 1973; Komadel et al. 1990; Suquet et al. 1991, 1994; Shinoda et al. 1995a; Vicente-Rodriguez et al. 1996; Madejová et al. 1998; Steudel et al. 2009). The same is true for 2:1 layer-ribbon type structures, such as sepiolite and palygorskite. Containing more octahedrally coordinated Mg2+ ions, and having larger channel dimensions, sepiolite is more susceptible to acid decomposition than is palygorskite (Suárez Barrios et al. 1995; Dékány et al. 1999; Komadel and Madejová 2013; Franco et al. 2014). For the same reason, the octahedral sheet of a magnesium-rich palygorskite is more easily dissolved by treatment with HCl as compared to its aluminum-rich counterpart (González et al. 1989).
Nanocomposites for food packaging applications
Published in Badal Jageshwar Prasad Dewangan, Maheshkumar Narsingrao Yenkie, Novel Applications in Polymers and Waste Management, 2018
Along with advanced food packaging, nanocomposites are used in various applications. Polymer nanocomposites can be utilized to prepare high-temperature lubricating coating application.47 Nanocomposite can be applicable for high-temperature application that was reported by Provenzano, Holtz.48 Cellulose nanocomposites with nanofibers can be utilized for medical applications.49 Nanostructured conducting polymers/ nanocomposites can be utilized to sensor applications; this was reported by Rajesh, Ahuja, and Kumar.50 Polymer and biopolymer-clay nanocomposites show attractive properties for electrochemical and electroanalytical applications, so they can utilized for such applications.51 A novel glucose biosensor was developed by using the chitosan-polypyrrole nanocomposites that was reported by Fang, Ni, Zhang, Mao, Huang, and Shen. This can be utilized for active packaging.52 Chitosan-clay nanocomposites are used as electrochemical sensors for the potentiometric determination of anionic species.53 Polymer clay nanocomposite can be used for catalytic degradation, adsorptive removal, and detection of contaminants; it is quite helpful in environmental view.54 Sepiolite-based nanocomposites make this nanoparticle the most attractive material for tissue engineering and environmental industrial applications.55 Nanocomposites of gold and poly(3-hexylthiophene) containing fullerene moieties are used in application in solar cell.56 One of the earliest application or nanocomposite developed by Toyota group for automobile application, the first commercial product of clay-based polymer nanocomposites was a timing-belt cover made from PA6 nanocomposites by Toyota Motors in the early of 1990s. This timing-belt cover exhibited good rigidity, excellent thermal stability, and no wrap. It also saved weight by up to 25%.57 Meanwhile, Ube America was attempted to prepare nanocomposite barriers for automotive fuel systems, using up to 5% nanoclay in PA6 and PA6/66 blends.58 There were various applications of different nanocomposites, tabulated in review by Pavlidoua and Papaspyrides.2 Lithium electrode application of ZnO-ZnFe2O4 nanocomposites was reported.59 The applicability of biopolymer nanocomposite to membrane application was reported in 2011.60
Effects of sepiolite and biochar on microbial diversity in acid red soil from southern China
Published in Chemistry and Ecology, 2019
Xu Qin, Qingqing Huang, Yiyun Liu, Lijie Zhao, Yingming Xu, Yetong Liu
Among the many remediation methods for contaminated soil, in situ chemical remediation technology is of importance widely because of its low cost, simple operation, quick effects, and no influence on normal farming, making this technology suitable for pollution control over large areas [3]. Sepiolite and biochar are two common immobilization remediation materials. Sepiolite is a silicate clay mineral that is fibrous, porous, and magnesium-rich, and its structural unit is composed of alternating silicon-oxygen tetrahedra and magnesium-oxygen octahedra, with a 0.37 nm–1.06-nm inner channel structure [3]. Due to this special structure, sepiolite has a larger specific surface area and higher ion exchange capacity, and it can be used for the remediation of soil and water environments contaminated by heavy metals [4]. In addition, some studies have shown that sepiolite has certain adsorption effects on organic pollutants such as pesticides [5]. Generally speaking, biochar produced by pyrolysis at high temperatures has a high carbon content and low residual organic matter content [6]. Moreover, compared with low-temperature biochar, high-temperature biochar has more abundant pore structure, larger specific surface area, higher aromaticity, and weaker polarity, which enable it to strongly adsorb certain aromatic organic molecules and heavy metals [7,8]. The use of in situ chemical remediation technology can not only immobilize the pollutants in the soil, but also repair the damaged soil environment, including improving the total organic carbon, pH, electrical conductivity, cation-exchange capacity, and enzyme activity of the soil [9,10].
Catalytic Ozonation by Copper Modified Sepiolite for the Degradation of Oxalic Acid in Water
Published in Ozone: Science & Engineering, 2023
Siru Zhang, Yuanxing Huang, Xiaoyue Wang, Bokang Liu, Junkai Zhao
Sepiolite is a kind of natural hydrated magnesium silicate mineral, belonging to the rhomboid crystal system and is in the form of porous fiber (Li et al. 2013; Liu, Pu, Ma 2012). Its molecular formula is Si12Mg8O30(OH)4(OH2)4 · 8H2O (Li et al. 2013; Liu, Pu, Ma 2012), and its crystal structure is shown in Figure 1 (Adapted from (Casal, Merino, Serratosa, Ruiz-Hitzky 2001; Sarossy et al. 2012; Yu et al. 2011)). Sepiolite crystals are composed of two continuous silicon-oxygen tetrahedral sheets above and below and a discontinuous magnesium-oxygen octahedral sheet in the middle, forming a 2:1 chain layer structural block (Liu, Pu, Ma 2012). The top layer of silicon-oxygen tetrahedron extends parallel and continuously along the fiber direction (c-axis), and every six silicon-oxygen tetrahedron units are connected through the periodic inversion of Si-O-Si bond at the top angle, which causes the discontinuity of magnesium-oxygen octahedron and forms microporous channels with a cross-sectional area of about 10.6 × 3.7 Å (Giustetto, Wahyudi, Corazzari, Turci 2011; Tartaglione, Tabuani, Camino 2008; Valentin, Lopez-Manchado, Rodriguez, Posadas, Ibarra 2007). The alternating arrangement of structural blocks and microporous tunnels constitutes large bundles of sepiolite fibers with 10–5000 nm length, 10–30 nm wideness and 5–10 nm thickness (Wang, Liang, Tang, Li, Han 2010). Due to the rupture of Si-O bond in the silicon-oxygen tetrahedron, there formed numerous silanol groups (Si-OH) on the outer surface of sepiolite (Yu et al. 2011). The Si-OH can be used as adsorption active centers to enhance the interaction with the adsorbed molecules. Sepiolite has a large specific surface area and exchangeable cation channel, which has a high application value in the field of adsorption and catalysis.