Influence of several experimental parameters on As and Se leaching from coal fly ash samples

Otero-Rey, José R.; Mato-Fernández, María J.; Moreda–Piñeiro, Jorge; Alonso-Rodríguez, Elia; Muniategui-Lorenzo, Soledad; López-Mahı́a, Purificación; Prada‐Rodríguez, D.

doi:10.1016/j.aca.2004.10.029

Cited by 45 publications

(27 citation statements)

References 16 publications

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“…Over 70% of Se can be removed at pH<1 (Dreesen et al, 1977), due to its primary surface association. As pH increases, the dominating anionic species HSeO 3 -and SeO 3 2-can be adsorbed on to the ash surface and removed from leachates (EPRI, 2008b;Otero-Rey et al, 2005) (Figure 1). Aluminium and, more importantly, Fe oxyhydroxides are ubiquitous in combustion by-products and show a strong affinity to sorb selenates (Cornelis et al, 2008;Iwashita et al, 2005;Otero-Rey et al, 2005).…”

Section: Seleniummentioning

confidence: 99%

“…As pH increases, the dominating anionic species HSeO 3 -and SeO 3 2-can be adsorbed on to the ash surface and removed from leachates (EPRI, 2008b;Otero-Rey et al, 2005) (Figure 1). Aluminium and, more importantly, Fe oxyhydroxides are ubiquitous in combustion by-products and show a strong affinity to sorb selenates (Cornelis et al, 2008;Iwashita et al, 2005;Otero-Rey et al, 2005). Maximum sorption is reached in the near neutral pH region (van der Hoek et al, 1994), and sorption decreases with increasing pH (EPRI, 2008b).…”

Section: Seleniummentioning

confidence: 99%

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Leaching behaviour of elements from coal combustion fly ash: An overview

Izquierdo

Querol

2012

International Journal of Coal Geology

632

379

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Coal-based power generation produces over 750 Mt of coal ash per year globally, but under 50% of world production is utilised. Large amounts of fly ash are either stored temporarily in stockpiles, disposed of in ash landfills or lagooned. Coal ash is viewed as a major potential source of release of many environmentally sensitive elements to the environment. This paper encompasses over 90 publications on coal fly ash and demonstrates that a large number of elements are tightly bound to fly ash and may not be easily released to the environment, regardless of the nature of the ash. This review provides an extensive look at the extent to which major and trace elements are leached from coal fly ash. It also gives an insight into the factors underlying the leachability of elements and addresses the causes of the mobility. The mode of occurrence of a given element in the parent coal was found to play an important role in the leaching behaviour of fly ash. The amount of calcium in fly ash exerts a dominant influence on the pH of the ash-water system. The mobility of most elements contained in ash is markedly pH sensitive. The alkalinity of fly ash attenuates the release of a large number of elements of concern such as Cd, Co, Cu, Hg, Ni, Pb, Sn or Zn among others, but at the same time, it enhances the release of oxyanionic species such as As, B, Cr, Mo, Sb, Se, V and W. The precipitation of secondary phases such as ettringite may capture and bind several pollutants such ash As, B, Cr, Sb, Se and V.

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Section: Seleniummentioning

confidence: 99%

Section: Seleniummentioning

confidence: 99%

Leaching behaviour of elements from coal combustion fly ash: An overview

Izquierdo

Querol

2012

International Journal of Coal Geology

632

379

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“…It has been described on previous studies that pH, S/L (solid-to-liquid) ratios, leaching time, ash properties (e.g. acidic or alkaline) and the leaching environment are the factors which affect the leaching behavior of arsenic [5][6][7][8][9][10][11]. Wang et al [12] investigated the effect of pH, S/L ratio, calcium addition and leaching time on the leaching behavior of As and Se from two major types of CFAs and they found that leaching of As and Se from CFA generally increased with increases in the S/L ratio and leaching time, and adsorption/desorption played a major role in As and Se leaching from CFA.…”

mentioning

confidence: 99%

Leaching Characteristic of Arsenic in Coal Fly Ash

Hartuti¹,

Kambara²,

Takeyama³

et al. 2017

JMSE-B

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Abstract:The leaching characteristics of arsenic from six CFA (coal fly ash) samples collected from a large scale power plant in Japan were investigated to evaluate more fully the rate of leaching of arsenic and related factors on determining arsenic leaching from different type of CFAs. The procedure of standard leaching tests according to Environmental Agency of Japan Notifications No. 13 was employed in this work. The results indicate that the leaching fractions of arsenic were low levels below 15%, and it was affected by CaO content in CFA. Leaching test results were compared with solution equilibrium calculation to consider the leaching mechanisms: however, experimental results were significantly lower than the equilibrium calculation results. To elucidate the leaching mechanisms, the leaching rate was investigated by extending the leaching tests for a long-term. The concentration of arsenic in the leachate was increased with time, and equilibrium between the solid phase (ash) and the leaching solution was reached in approximately 120 days. It is found that the constant a has a good relationship with CaO content in CFAs, in which the constant a (indicated leaching rate of arsenic) was decreased with an increase of CaO content in fly ash. Therefore, the value of the rate constant a can be said to be the main factor determining arsenic leaching.

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“…Exposure to the environment has had significant effects on waste chemical landfill storage and the acidity was one of the parameters deciding this (Otero-Rey et al 2005). It has been important to monitor the pH of the landfill wastes and optimize the process parameters to slow the chemical reactions between the environment and immobilized pollutants.…”

Section: Resultsmentioning

confidence: 99%

Investigating the chemical stabilization of hazardous waste material (fly ash) encapsulated in Portland cement

Sobiecka

2013

Int. J. Environ. Sci. Technol.

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Portland cement has been suggested as an effective stabilization (physico-chemical) method for hazardous waste. This research explored the immobilization of metals in various mixtures of Portland cement and fly ash waste sampled from coal power plant in the province of Lodz, central Poland. The stabilization of fly ash in Portland cement was investigated under a wide range of pH conditions (3-12). Leachability tests were used to determine the efficiency of the encapsulation by studying the dissolution of alkaline metals (sodium, potassium) and alkaline earth metals (calcium, magnesium). The lowest value of leached metals was obtained for ratio of ash to cement of 1:10 in a case of sodium and calcium, while ratio 1.5 gave the lowest leached effects for potassium and magnesium. The high effectiveness of solidification/stabilization process was gained in high pH values (9-11).

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Influence of several experimental parameters on As and Se leaching from coal fly ash samples

Cited by 45 publications

References 16 publications

Leaching behaviour of elements from coal combustion fly ash: An overview

Leaching behaviour of elements from coal combustion fly ash: An overview

Leaching Characteristic of Arsenic in Coal Fly Ash

Investigating the chemical stabilization of hazardous waste material (fly ash) encapsulated in Portland cement

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