Leaching of coal fly ash with sulphuric acid for synthesis of wastewater treatment composite coagulant

Apua, M. Clotilde; Nkazi, B. D.

doi:10.1080/00084433.2022.2044689

Cited by 6 publications

(6 citation statements)

References 62 publications

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“…The synthesis of coal fly ash-based composite coagulant is reported in our previous paper (Apua and Nkazi 2022). In fact, Fe, Al, Si, Ca and Mg were extracted from coal fly ash by sulphuric acid leaching to synthesize the coagulant used in this study.…”

Section: Coagulantmentioning

confidence: 99%

“…The abundant generated by-product of coal-fired power plants, most coal fly ash contains satisfactory quantities of aluminium, iron, silicon, magnesium and calcium oxides which are suitable for synthesizing composite coagulants. Thus, utilizing coal fly ash to make complex coagulants can lead to significant savings, as these byproducts cost much less than other industrial-grade aluminium or iron ores (Apua and Simate 2018;Apua and Nkazi 2022). More importantly, such an approach to using coal fly ash would contribute to reducing the environmental pollution caused by the storage and disposal techniques presently used in many countries (Apua 2021).…”

Section: Introductionmentioning

confidence: 99%

“…Thus, utilizing coal fly ash to make complex coagulants can lead to significant savings, as these byproducts cost much less than other industrial-grade aluminium or iron ores (Apua and Simate 2018;Apua and Nkazi 2022). More importantly, such an approach to using coal fly ash would contribute to reducing the environmental pollution caused by the storage and disposal techniques presently used in many countries (Apua 2021).…”

Section: Introductionmentioning

confidence: 99%

“…At present, there is considerable interest in coal fly ash as a raw material for water contamination control due to its cheapness and availability. In our previous study, coal fly ash was utilized to produce a composite coagulant (Apua and Nkazi, 2022) which was used in this investigation to treat mine wastewater for the removal of Fe, Mg, Mn, Ni, Al, Si, Ca and Zn. A survey of the literature reveals no reported research on the adsorptive aspect of coagulation of Fe, Mg, Mn, Ni, Al, Si, Ca and Zn by coal fly ash-based coagulants.…”

Section: Introductionmentioning

confidence: 99%

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Treatment of mine wastewater using a coal fly ash-based coagulant: Coagulation adsorption isotherm study

Apua

Simate

Bada

2023

Preprint

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The mining industry produces large volumes of wastewater that may cause detrimental environmental pollution due to its high concentrations of harmful metal ions. This study used a synthesized coal fly ash-based composite coagulant (containing Al3+, Fe3+, Mg2+, Si4+ and Ca2+) to remove impurities such as Fe, Mg, Mn, Ni, Al, Si, Ca, Zn and total dissolved solids from mine wastewater. Coagulation process optimization was studied by varying the coagulant dosage, pH, temperature and coagulation time. Models that describe coagulation adsorption mechanisms have not been established for adsorption on hydroxide precipitates derived from a coal fly ash-based composite coagulant. The coagulation data for the removal of the mentioned pollutants from mining effluents were analyzed in light of adsorption isotherm, including Langmuir, Freundlich, Temkin and BET isotherm models. Results showed that the coal fly ash-based composite coagulant is effective in removing the studied pollutants in mine wastewater. Floc formation analyses revealed that destabilization by charge neutralization and sweep flocculation happened during coagulation. Analyses of the produced sludge composition showed that adsorption happened during coagulation. In general, the coagulation adsorptions are exothermic processes as indicated by Temkin and BET isotherm models. The assessment of the regression coefficients of determination from the four adsorption models for the fit of the coagulation data showed that the \({R}^{2}\) values for Temkin and BET were in the suitable range, and they could be considered as the coagulation adsorption models for this investigation in general. The application of such a coagulant can be easily adopted in mine effluent treatment plants, thereby reducing mine wastewater pollution issues. This new application of coal fly ash can be extended to the treatment of other wastewaters.

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Section: Coagulantmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Treatment of mine wastewater using a coal fly ash-based coagulant: Coagulation adsorption isotherm study

Apua

Simate

Bada

2023

Preprint

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“…In previous investigations, various approaches for CFA treatment for alumina extraction have been proposed, including alkaline [10][11][12], acidic [13][14][15], and combined, as well as preliminary thermal activation [5,16] or sintering with an additive [17][18][19]. Acid methods are considered the most effective for high-silica raw materials treatment [20,21] as they allow for the silica to remain in the residue after the acid leaching, without the loss of Al and NaOH with the desilication product [22,23].…”

Section: Introductionmentioning

confidence: 99%

Kinetics of Aluminum and Scandium Extraction from Desilicated Coal Fly Ash by High-Pressure HCl Leaching

Shoppert,

Valeev,

Loginova

2023

Metals

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Coal fly ash (CFA) is a waste that forms via coal combustion in thermal power stations. CFA consists of numerous components, whose recovery can address environmental and resource concerns associated with sustainable development. Most of the alumina (Al2O3) and rare-earth elements (REEs) in CFA are contained in the amorphous glassy mass and in the refractory mullite phase (3Al2O3·SiO2), which can be dissolved only using high-pressure acid leaching (HPAL). In this paper, the method of preactivation of CFA by treatment with a highly concentrated NaOH solution is used to increase the efficiency of Al and Sc extraction during HPAL. This method allows for the elimination of an inert aluminosilicate layer from the surface of mullite, transferring the REEs into an acid-soluble form. The Al and Sc extraction can reach 80% after HCl HPAL at T = 170 °C and a 90 min duration. According to the kinetic data, the dissolution of Al follows the surface chemical reaction and intraparticle diffusion shrinking core models in the initial and later stages of leaching, respectively. A high activation energy of 52.78 kJ mol−1 was observed at low temperatures, and a change in the mechanism occurred after 170 °C when the activation energy decreased to 26.34 kJ mol–1. The obtained activation energy value of 33.51 kJ mol−1 for Sc leaching indicates that diffusion has a strong influence at all studied temperatures. The residue was analysed by SEM-EDX, XRF, BET, and XRD methods in order to understand the mechanism of DCFA HPAL process.

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An efficient and environmental friendly strategy for alumina extraction and Fe–Si alloys production from coal fly ash by combining vacuum thermal reduction, alkali dissolving, and magnetic separation

Rao

Yuan

et al. 2023

Journal of Cleaner Production

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Leaching of coal fly ash with sulphuric acid for synthesis of wastewater treatment composite coagulant

Cited by 6 publications

References 62 publications

Treatment of mine wastewater using a coal fly ash-based coagulant: Coagulation adsorption isotherm study

Treatment of mine wastewater using a coal fly ash-based coagulant: Coagulation adsorption isotherm study

Kinetics of Aluminum and Scandium Extraction from Desilicated Coal Fly Ash by High-Pressure HCl Leaching

An efficient and environmental friendly strategy for alumina extraction and Fe–Si alloys production from coal fly ash by combining vacuum thermal reduction, alkali dissolving, and magnetic separation

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