Preparation and evaluation of a mesoporous calcium-silicate material (MCSM) from coal fly ash for removal of Co(II) from wastewater

Qi, Guangxia; Lei, Xuefei; Li, Lei; Yuan, Chao; Sun, Yinglong; Chen, Jianbo; Chen, Jian; Wang, Yi; Hao, Jiming

doi:10.1016/j.cej.2015.05.077

Cited by 68 publications

(22 citation statements)

References 45 publications

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“…A certain degree of surface adsorption and surface complexation by hydrated Me ions and subsequent precipitation of Me-oxyhydrates onto the C-A-S-H surface cannot be fully excluded, as indicated before, although we found no analytical evidence for such removal mechanism(s) to take place under the given experimental conditions. However, Qi et al [62] have presented some evidence of coupled chemical precipitation, physisorption and structural incorporation phenomena for the adsorption of Co 2þ ions by mesoporous C-S-H. In conclusion, the removal mechanisms of Me ions by aluminosilicate hydrates are highly complex and include ion exchange in the interlayer, isomorphous substitution in the octahedral and tetrahedral layers, and possibly surface (ad)sorption and chemical precipitation ( Fig.…”

Section: Potential Removal Mechanism(s) For Me Ions By C-a-s-h and Trmentioning

confidence: 95%

Removal of heavy metals (Co, Cr, and Zn) during calcium–aluminium–silicate–hydrate and trioctahedral smectite formation

et al. 2019

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Hydrated aluminosilicates were synthesized with and without aqueous heavy metals (Me), such as cobalt (Co), chromium (Cr), and zinc (Zn), by a sol-gel process at different initial molar ratios of Ca/(Si ? Al) (0.6-1.6) and Me/Si (0.0-2.0), and constant Al/Si ratio (0.05) using equilibrium-approaching experiments. The chemical composition of the reactive solutions during aluminosilicate precipitation and maturation was monitored by ICP-OES. The mineralogy, nanostructure, and chemical composition of the precipitates were studied by XRD and high-resolution TEM. At Me/Si ratios B 0.2, calcium-aluminium-silicate-hydrates (C-A-S-H) with a defect 14 Å tobermorite-like structure formed, whereas at a Me/Si ratio of 2.0, either trioctahedral Co-and Zn-smectite or amorphous Cr gels precipitated, independent of the initial Ca/(Si ? Al) ratio used for gel synthesis. The immobilization capacities for Co 2þ , Cr 3þ , and Zn 2þ by C-A-S-H, Cr gel, and trioctahedral smectite are 3-40 mg/g, 30-152 mg/g, and 122-141 mg/g, respectively. The immobilization mechanism of heavy metals is based on a combination of isomorphous substitution, interlayer cation exchange, surface (ad)sorption, and surface precipitation. In engineered systems, such as underground concrete structures and nuclear waste disposal sites, hydrated aluminosilicates should exhibit a high detoxication potential for aqueous heavy metals.

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Section: Potential Removal Mechanism(s) For Me Ions By C-a-s-h and Trmentioning

confidence: 95%

Removal of heavy metals (Co, Cr, and Zn) during calcium–aluminium–silicate–hydrate and trioctahedral smectite formation

et al. 2019

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“…During the first process, there exists a strong electrostatic interaction between the electronegative ceramic surface and divalent ions at pH > pH PZC , 49 moreover, the functional groups on CM and the chemical (13) [42] Coal gangue/biochar Cu 2+ 2.37 [43] Coal fly ash Cu 2+ 0.048 [44] Coal fly ash Pb 2+ 0.36 [45] Blast furnace slag Pb 2+ 5.52 [46] Bentonite Pb 2+ 7.56 [46] Commercial AC Pb 2+ 6.68 [16] Coconut-shell-based AC Pb 2+ 21.88 [17] Hazelnut husks-based AC Pb 2+ 13.05 [18] Cu 2+ 6.65 [18] Rubber wood sawdust based AC Cu 2+ 5.72 [19] Eucalyptus barkbased AC bonds on heavy metal ions contribute to the complexation on the surface of CM. 50 Thus, most of the available sites (-SiOH, -AlOH) are occupied instantly. The reaction happened in the process can be described as Equations (15) and (16).…”

Section: Adsorption Mechanismmentioning

confidence: 99%

Novel design of microsphere adsorbent for efficient heavy metals adsorption

Wang

Liu

Rong

et al. 2020

Int J Applied Ceramic Tech

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The fabrication of high‐efficiency and low‐cost adsorbent for the wastewater treatment is a challenging task. In this study, a hollow sphere adsorbent was synthesized from solid waste coal gangue through a facile spray drying method and subsequent calcination. The structure of the synthesized coal gangue microsphere (CM) have been characterized by multimethods including X‐ray diffraction, scanning electron microscope, Fourier transform infrared, and others. The factors influencing the adsorption for Cu2+ and Pb2+ by CM were also investigated systemically; pH between 6 and 8 was found to be optimal for Cu2+ and Pb2+ adsorption. The isotherm and kinetic analysis reveal that the adsorption process could be well represented by Langmuir and pseudo–second‐order model with a higher R2 and low χ2 value. According to Langmuir model, the maximum adsorption capacity was calculated to be 6.570 and 18.904 mg/g for Cu2+ and Pb2+ at 25°C, respectively. The adsorption mechanism was proposed to contain not only the surface reaction process, but also the diffusion process. Consequently, the economic and environmental benefits make CM a promising adsorbent in wastewater treatment.

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“…Importantly, it has much potential for environmental applications [5][6][7][8]. Thus, the desilication liquid could be a good silicon source for C-S-H synthesis, and this is also quite possible way to the effective utilization of desilication liquid [9,10].…”

Section: Introductionmentioning

confidence: 99%

Characterizations of calcium silicate hydrates derived from coal fly ash and their mechanisms for phosphate removal

Tian

Sasaki

2019

DWT

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Coal fly ash is an industrial waste generated from the thermal power plant and a large amount of it could be produced annually in the world, which can cause serious environmental problems. Reutilization of coal fly ash could be imperative to alleviate the environmental pressure. Thus, in the present study, coal fly ash was used as silicon source for the synthesis of calcium silicate hydrates (C-S-Hs) though the desilication process. Two kinds of C-S-Hs was synthetized at 100°C and room temperature respectively, with the fixed Ca/Si molar ratio of 1.2, and adopted as the adsorbents for phosphate. The properties of them were characterized using XRD, SEM, FTIR, TG-DTA as well as surface area and pore analysis. Compared to C-S-H synthesized from high temperature, the C-S-H obtained at room temperature possessed high purity and larger surface area. Therefore, synthesis by agitation at room temperature could be an alternative method to produce C-S-H materials from desilication liquid of coal fly ash, and this could save infrastructure cost and energy consumption. Both C-S-H materials have good ability to immobilize phosphate pollutant (higher than 100 mg•g-1). The specific mechanisms of phosphate removal using C-S-H include several steps: firstly, phosphate ion was immobilized by binding with Ca 2+ and forming aggregates, and the C-S-H structures were gradually corroded. Eventually, hydroxyapatite was formed after the C-S-H structure was totally destroyed.

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Preparation and evaluation of a mesoporous calcium-silicate material (MCSM) from coal fly ash for removal of Co(II) from wastewater

Cited by 68 publications

References 45 publications

Removal of heavy metals (Co, Cr, and Zn) during calcium–aluminium–silicate–hydrate and trioctahedral smectite formation

Removal of heavy metals (Co, Cr, and Zn) during calcium–aluminium–silicate–hydrate and trioctahedral smectite formation

Novel design of microsphere adsorbent for efficient heavy metals adsorption

Characterizations of calcium silicate hydrates derived from coal fly ash and their mechanisms for phosphate removal

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