Modern Views on Desilicification: Biosilica and Abiotic Silica Dissolution in Natural and Artificial Environments

Ehrlich, Hermann; Demadis, Konstantinos D.; Pokrovsky, Oleg S.; Koutsoukos, Petros G.

doi:10.1021/cr900334y

Cited by 238 publications

(155 citation statements)

References 325 publications

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“…These spicules, which are much denser than diatoms and more resistant to dissolution, have evidence of dissolution pitting while the diatom fragments do not (J Coenen 2015, unpublished data). The observed pitting is analogous to microbially mediated pits observed on spicules recovered from other marine sediments ( [65]; reviewed in [66]). While the observed dissolution (or etch) pits could result from dissolution of sponge spicules in silica-limited waters (silica concentrations in SLW have not been measured), it is surprising that the opaline silica of diatom fragments did not manifest pits.…”

Section: Biogeochemical Results From Subglacial Lake Whillanssupporting

confidence: 60%

Subglacial Lake Whillans microbial biogeochemistry: a synthesis of current knowledge

Mikucki

Lee

Ghosh

et al. 2016

Phil. Trans. R. Soc. A.

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Liquid water occurs below glaciers and ice sheets globally, enabling the existence of an array of aquatic microbial ecosystems. In Antarctica, large subglacial lakes are present beneath hundreds to thousands of metres of ice, and scientific interest in exploring these environments has escalated over the past decade. After years of planning, the first team of scientists and engineers cleanly accessed and retrieved pristine samples from a West Antarctic subglacial lake ecosystem in January 2013. This paper reviews the findings to date on Subglacial Lake Whillans and presents new supporting data on the carbon and energy metabolism of resident microbes. The analysis of water and sediments from the lake revealed a diverse microbial community composed of bacteria and archaea that are close relatives of species known to use reduced N, S or Fe and CH4 as energy sources. The water chemistry of Subglacial Lake Whillans was dominated by weathering products from silicate minerals with a minor influence from seawater. Contributions to water chemistry from microbial sulfide oxidation and carbonation reactions were supported by genomic data. Collectively, these results provide unequivocal evidence that subglacial environments in this region of West Antarctica host active microbial ecosystems that participate in subglacial biogeochemical cyclingauthorsversionPeer reviewe

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Section: Biogeochemical Results From Subglacial Lake Whillanssupporting

confidence: 60%

Subglacial Lake Whillans microbial biogeochemistry: a synthesis of current knowledge

Mikucki

Lee

Ghosh

et al. 2016

Phil. Trans. R. Soc. A.

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“…Control of silica polycondensation, in principle, can be achieved by use of chemical additives [10] or capital-intensive water desilicification [11][12][13][14][15]. Unfortunately, traditional scale control methods (inhibition and crystal modification) applied to crystalline mineral salt precipitates [16], do not apply to silica because of its amorphous state [17]. Therefore, carefully designed inhibition approaches have to be implemented for controlling silica deposition.…”

Section: Introductionmentioning

confidence: 99%

Profound “turn-off” effects of anionic polymers on the inhibitory activity of cationic polyallylamine in the prevention of silica scale

Spinthaki¹,

Stathoulopoulou²,

Demadis

2015

Int. J. Corros. Scale Inhib.

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Colloidal/amorphous silica (SiO 2 nH 2 O, n is variable) is considered as the most undesirable inorganic precipitate that forms during various processes in silica-supersaturated industrial waters. In this paper we present how certain polymeric chemical additives can prevent silicic acid polymerization to form colloidal silica, which may lead to deposition onto industrial equipment. More specifically, stabilization of silicic acid is accomplished by using a cationic polymer, polyallylamine hydrochloride (PALAM), in supersaturated silica solutions (starting silica concentration in the form of silicate 500 ppm, or 8.3 mM sodium orthosilicate, Na 2 SiO 3 ·5H 2 O, expressed as SiO 2 ) at pH = 7. PALAM is a linear homopolymer that carries one amine side functional group every two carbon atoms, so it becomes protonated at circumneutral pH, rendering the molecule cationic. Its blends with anionic polymers such as carboxymethylinulin (CMI), poly(acrylamide-co-acrylic acid) (PAM-co-AA) and phosphonomethylated chitosan (PCH) are also studied for their silica scale inhibition efficiency.

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“…Os mecanismos podem ser atribuídos à ação enzimática e lixiviação ácida. [14,17,23]. Em conclusão, foi possível observar que o fungo Fusarium oxysporum pode ser usado para biotransformar a sílica amorfa presente na cinza da casca de arroz através da ação microbiana.…”

Section: Análise Da Microestrutura Das Partículas Da Ccaunclassified

“…Alguns organismos unicelulares (bactérias e algas) também produzem materiais inorgânicos de forma intra ou extracelular. Os exemplos mais importantes incluem esponjas diatomáceas, as quais sintetizam materiais silícicos [11][12][13][14]. Os fungos também podem ser empregados especialmente na produção de enzimas de forma extracelular para a biotransformação de diversos materiais como zircônia e titânia [15][16].…”

Section: Introductionunclassified

Biotransformação da cinza da casca de arroz em nanopartículas de sílica mediante Fusarium oxysporum

et al. 2012

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RESUMONeste estudo avaliou-se uma rota biológica à temperatura ambiente para a biotransformação da cinza da casca de arroz em nanopartículas de sílica empregando o fungo Fusarium oxysporum. Foram realizados ensaios e monitorou-se a produção de biomassa fúngica, pH e concentração de sílica solúvel em meio de cultura contendo cinza durante 270 h a uma temperatura de 25°C, com uma concentração inicial de biomassa de 0,3 g/L (base úmida) in situ. A cinza antes e após o tratamento foi analisada por espectroscopia de infravermelho IV; MEV e DRX. Os resultados deram indícios que com o processo biológico à temperatura ambiente ocorre uma biotransformação da cinza da casca de arroz, gerando sílica solúvel e cristalina no meio de cultura. Tais resultados indicam a possibilidade da síntese por via biológica de nanomateriais óxidos.Palavras-chave: Cinza da casca de arroz, sílica, bioprocessamento, Fusarium oxysporum, nanomateriais. Biotransformation of rice husk ash in silica nanoparticles by Fusarium oxysporum ABSTRACTIn this study a biological route at room temperature for the biotransformation of rice husk ash (RHA) in silica nanoparticles using the fungus Fusarium oxysporum was evaluated. Some tests were carried out by monitoring the fungal biomass production, pH, soluble silica on culture medium with rice husk ash and fungi, during 270 h at a 25°C temperature and 0.3 g/L (wet basis) biomass concentration, in situ. The RHA was analyzed before and after processing by SEM and XRD. The results indicated that trhrough a biological process at room temperature a biotransformation of rice husk ash is reached by bioleaching and enzymatic action allowing the synthesis of oxidic nanomaterials. Keywords: Rice husk ash, silica, bioprocessing, Fusarium oxysporum, nanomaterials INTRODUÇÃOA cinza da casca de arroz (CCA) é um subproduto agrícola empregado como biocombustível em diferentes processos como pirólise, gaseificação e combustão em leitos fixos e fluidificados especialmente em indústrias de beneficiamento de arroz [1][2][3]. A quantidade de sílica presente na CCA pode variar entre 80 e 97% dependendo das condições de queima e sua estrutura encontra-se, principalmente, na forma amorfa [1,4].A sílica é um material inorgânico empregado em uma ampla gama de aplicações comerciais como peneiras moleculares, suporte para catalisadores, materiais eletrônicos, assim como na indústria civil como pozolana no cimento e na produção de abrasivos de carbeto de silício, entre outros [4][5][6][7]. As partículas de sílica apresentam baixa densidade e alta resistência térmica e química. Com a diminuição no tamanho de partícula, a reatividade da sílica aumenta significativamente, facilitando, por exemplo, o processo de sinterização. Atualmente, a síntese de nanoestruturas da sílica é feita em condições extremas de pH, usando produtos como HCl, H 2 SO 4 , HNO 3 , NaOH e NH 4 OH [8], além de pressões e temperaturas elevadas [9], eventual-

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Modern Views on Desilicification: Biosilica and Abiotic Silica Dissolution in Natural and Artificial Environments

Cited by 238 publications

References 325 publications

Subglacial Lake Whillans microbial biogeochemistry: a synthesis of current knowledge

Subglacial Lake Whillans microbial biogeochemistry: a synthesis of current knowledge

Profound “turn-off” effects of anionic polymers on the inhibitory activity of cationic polyallylamine in the prevention of silica scale

Biotransformação da cinza da casca de arroz em nanopartículas de sílica mediante Fusarium oxysporum

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