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Biogenic Silica Indicator of Paleoproductivity in Lacustrine Sediments of Svalbard, Arctic
Published in Neloy Khare, Climate Change in the Arctic, 2022
Shabnam Choudhary, G. N. Nayak, Neloy Khare
Biogenic silica is a type of amorphous silica derived from diatoms and other siliceous microorganisms (Liu et al. 2014). Biogenic silica documents direct measure of biological products from the siliceous algae and diatoms (Conley 1998; Kaplan et al. 2002). It is produced in the euphotic zone by the diatoms, predominantly in the high-latitude areas. Although the biogeochemical cycle of silicon is slow as compared to other elements like oxygen, carbon and nitrogen, its sedimentation rate is rapid (Shan et al. 2011); therefore, silicon can be preserved in the form of biogenic silica in sediments (Birks et al. 2004; Shan et al. 2011). In lakes, nutrient concentration in water and surface temperature affects productivity. Therefore, variation in biogenic silica content can reflect changes in past climate conditions. Earlier studies from lakes of different parts of the globe such as Lake Baikal, Lake Pipa, Lake Huguangyan Maar and lakes from the Arctic region reported that a high concentration of bSi represents warm and humid climate conditions. Simultaneously, lower values indicate cold and dry climatic conditions (Shan et al. 2011). These studies suggested that changes in diatom production are related to changes in climate. Therefore, biogenic silica can be used to reconstruct past climate changes in lake sediments.
Biogenic silicon dioxide nanoparticles processed from natural sources
Published in Particulate Science and Technology, 2021
Kinga Adach, Dora Kroisova, Mateusz Fijalkowski
Biogenic silica is new group of nanoparticles that are found in plants and residual plant-derived products (e.g., rice husks) characterized by amorphous structure, small size, shape and they origin (Khorsand, Kiayee, and Masoomparast 2013). Similarly as in the case of chemical approach of preparing SiO2 particles, pretreatment and processing of silica particles from waste materials heavily influences the obtained structure, morphology, surface area and pore size distribution of the particles. (Alyosef et al. 2013). Hence, silica nanoparticles isolated from renewable waste materials have many potential applications. Nanostructured composites NiO/SiO2 (silica from rice hulls) can be implemented in optical detectors of harmful gases (CO carbon oxide, NOx nitrogen oxides), (Rebelo et al. 2019). Samples of rice hull ash, which is rich in amorphous silica, were successfully implemented in water treatment (Adams et al. 2014). Detailed material analysis of the decomposition properties of organic waste materials allows for a better understanding of the preparation of silica nanoparticles in a reproductive manner. It is obvious that each natural material is different, nevertheless, advanced analysis is necessary in order to avoid mistakes when scaling up from a laboratory to an industrial setting, which in the current production scale of many millions of tons per year of wastes is extremely important.
Sustainable synthesis of silica nanoparticles from agricultural waste and its utilization in modern technology: A review
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Aiman Shahbaz, Mahnoor Ayaz, Usama Bin Khalid, Laiba Liaqat
Many scientists worked together to create SiNPs from WH, an agricultural waste. Plant-mediated nanoparticle production was investigated by Parveen et al. as a green chemistry technique that blends nanotechnology and plants. As a result, novel strategies for synthesizing NPs at room temperature, neutral pH, at a cheap cost, and in an environmentally benign manner are being studied. With these objectives in mind, nanomaterials have been produced in a variety of ways. The most effective biological alternatives appear to be plants and plant extracts. Plants are the “chemical factories” of nature. They are both cost-effective and low-maintenance. Terzioglu et al. studied that WH is a significantly available waste obtained from the wheat milling process. Since it contains non-crystalline silica, it can also be considered for the production of value-added products. This research provides a thorough summary of the studies done on the characteristics and use of WH as a source of silica. WH is subjected to be used for the low-cost and sustainable production of silica-based materials such as zeolite, metal silicates, silica-based ceramics, aerogel, and composites (Terzioğlu, Yücel, and Kuş 2019). Porrang et al. investigated the production of SiNPs from the WH. The initial stage was to extract biogenic silica from the husk via acid leaching, after which sodium silicate was obtained as a silica precursor. Mesoporous SiNPs were produced using the sol-gel process, which involved adding sodium silicate to the template mixture while constantly stirring it. Furthermore, the influence of natural source and precursor addition on the morphology and physicochemical properties of nanocarriers was studied using characterization techniques such as XRD, BET, FT-IR, and SEM. The analysis indicated that wheat husk-based nanocarriers were made up of spherical NPs with narrow cylindrical pores (Porrang et al. 2021).
Nanomaterials against pathogenic viruses: greener and sustainable approaches
Published in Inorganic and Nano-Metal Chemistry, 2020
Ghazaleh Jamalipour Soufi, Siavash Iravani
Silica-based NPs provide a versatile toolbox for biomedical applications due to their biocompatibility and bioactivity, and especially can be employed for sustained delivery and enhanced bioavailability of drugs (like antiviral drugs). Currently, natural-resources-based silica has garnered remarkable interest in the materials science and biomedicine fields due to the availability, low- cost and eco-friendliness of these materials. A number of living organisms, including higher plants and diatoms are capable of accumulating, storing and processing silicon to create ornate hierarchical patterned biogenic silica.[42] It was reported that silica can inhibit viruses transport in unsaturated condition.[43] They can be employed as promising alternatives against pathogenic viruses, especially in the case of SARS-CoV-2. In one study, silicon NPs (∼5-50 nm) produced by grinding of porous silicon can act as efficient scavengers of HIV and RSV.[42] This natural-resource-based silica has garnered remarkable interest in the materials science and biomedicine fields due to the availability, low-cost and eco-friendliness of these materials. In vitro evaluations showed significant suppression of the viral activities in the existence of silicon NPs with concentration above 0.1 and 0.01 mg/mL for HIV and RSV, respectively.[42] Results revealed that binding of the virions with the prepared NPs supposed to be universal for various enveloped viruses. The value of zeta-potential exhibited significant silicon NP-virion interaction, which was accompanied by the charge transfer between them; obviously, NPs with zeta-potential near zero will undergo remarkable aggregation in the suspensions. Therefore, the cytotoxic concentration of silicon NPs is of the order of 1 mg/mL, and thus these nanomaterials can be suggested for applications in innovative harmless approaches of antiviral treatment, but further systematic studies are still needed, especially regarding the mechanistic aspects of scavenging effects of the NPs [42] (Figure 2).