Silica scale formation and effect of sodium and aluminium ions -<sup>29</sup>Si NMR study

Lunevich, L; Sartipy, Peter; Smallridge, Andrew J.; Gray, Stephen

doi:10.1039/c5ew00220f

Cited by 17 publications

(40 citation statements)

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“…Aqueous Silica and Silica Polymerisation DOI: http://dx.doi.org /10.5772/intechopen.84824 ii. The results documented in the research [1][2][3]5] shown that NaCl in relatively high concentrations (8-60 g/L) depress silica solubility limits showing silica fouling at 90-81 mg/L, but no silica deposition or single silica bonding to the membrane surface was found on the membrane surface suggesting that precipitated silica remained in the recycled stream, again the indication on various silica polymerisation processes via silica species which were formed during the specific conditions, silica concentrations, pH [1][2][3][4][5][6].…”

Section: Discussionmentioning

confidence: 93%

“…According to Sjorberg, Lunevich, and others soluble or dissolved (reactive) silica contains different silica species; monomer, dimers, trimmers and other polymers of silicic acid in different solutions [43][44][45][46][47][48][49][50][51]. These dissolved silica species can be presented in various ionisation states which depend on the pH of solutions, silica concentrations, presence of other silica species and other cations and anions [3,5,[43][44][45][46][47][48][49][50][51]. During the reverse osmosis chemical separation of water molecules (separation of salts) dissolved silica accumulate on the membrane surface which could lead to silica scale formation on the membrane surface.…”

Section: Discussionmentioning

confidence: 99%

“…Interesting that not all highly super-saturated silica streams lead to scaling of membrane surfaces [1,3,5]. According to Lunevich in high salinity waters sodium could prevent silica deposition on the membrane surface [1,5].…”

Section: Discussionmentioning

confidence: 99%

“…In this chapter, the past and recent studies on various aqueous silica species and its impact are discussed. Behaviours of aqueous silica species were studies using reverse osmosis (RO) desalination systems and 29 Si NMR techniques and coagulation to gain better understanding of aqueous silica species polymerisation and practical implications of these techniques [1][2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…Practical silica solubility or the solubility defined empirically is a key for prevention of silica polymerisation in RO desalination systems [1][2][3][4][5]7]. Soluble or dissolved (reactive) silica contains different forms of silica or silica species ( Figure 1); monomer, dimers, trimmers and other polymers of silicic acid in different solutions [5,7,8,12].…”

Section: Introductionmentioning

confidence: 99%

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Aqueous Silica and Silica Polymerisation

Lunevich¹

2020

Desalination - Challenges and Opportunities

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Dissolved silica (SiO 2) is supplied to the environment by chemical and biochemical weathering processes despite the fact that dissolved silica has many stable and unstable dissolved forms (silica species). The processes involve ion substitution and chelate forming reactions which remove mineral lattice cations. The concentration of dissolved silica in natural waters is determined by a buffering mechanism which is thought to require the sorption and desorption of dissolved silica by soil particles. For instance average concentration of silica in some groundwater like coal seam gas water ranges between 0.1 and 80.0 ml/L. The dissolution process of silica and silicates from rocks into water is mainly due to hydrolysis of silica-oxygen-silica bonds, resulting in the liberation of silicic acid (Si(OH) 4) and silicates into aqueous phase. It is difficult to define precisely the term 'aqueous silica' as there is an array of silica species possible. Temperature, pH and ionic strength have a substantial influence on the solubility of amorphous silica and forms of silica present in a solution. This phenomenon of silica chemistry can be explained by presence of various silica species, which frequently define silica solubility and physicochemical reactions. It appears that some silica species behave as organics. For seawater the composition is relatively balanced; though, this might not explain low silica precipitation in seawater desalination.

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Aqueous Silica and Silica Polymerisation

Lunevich¹

2020

Desalination - Challenges and Opportunities

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An optimization study for preventing silica gelation and improving filtration effectiveness during pH reduction of high concentration silica solutions

et al. 2023

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The steam generation processes at the steam-assisted gravity drainage facilities result in huge quantities of wastewater streams, which are characterized by high pH and high silica levels. These concentrated streams need to be neutralized before their disposal via down-hole injection. The neutralization of these high-pH brines results in the formation of a gel-like substance, which makes it difficult to filter the amorphous silica gel. The wastewater used in this study was synthetically prepared using sodium metasilicate to mimic highconcentration silica solutions. Our experiments did not show any advantage of a two-step pH-neutralization process over the single-step process for suppressing silica gelation. A systematic experimental campaign was undertaken to investigate the effects of SiO 2 concentration, NaCl:SiO 2 ratio, and pH on the residual silica concentration, percent silica removal, filtration rate, and filtration effectiveness. For NaCl:SiO 2 ratios higher than 4.5, silica precipitation during pH reduction did not lead to the formation of gel or sol. The response surface methodology (RSM), based on the Doehlert design of experiments, was implemented to optimize the responses and provide high efficacy with fewer experiments. The results from the analysis of variance (ANOVA) analyses of the experimental data were used to evaluate the significance of each term in the quadratic model. 3D response surfaces and 2D contour plots were generated for determining the optimal ranges of independent factors for achieving the maximum silica removal, the highest filtration rate, the best filtration effectiveness, and the minimum residual silica concentration. An optimum operating region was established from the RSM analysis and overlay plot.

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