Leaching characteristics of boron and selenium for various coal fly ashes

Iwashita, Akira; Sakaguchi, Yuka; Nakajima, Tsunenori; Takanashi, Hirokazu; Ohki, Akira; Kambara, Shinji

doi:10.1016/j.fuel.2004.11.002

Cited by 81 publications

(60 citation statements)

References 17 publications

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“…The leachable concentrations range over several orders of magnitude as a function of the mode of Ca occurrence and concentration in the fly ash, the proportion of each phase and the leaching test performed. With only water, the amounts of Ca leached could easily fall in the 100-15000 mg/kg range (Iwashita et al, 2005;Izquierdo et al, 2011;Medina et al, 2010;Moreno et al, 2005). The water extractable proportions measured for a large set of data are in the 7-14% range (Moreno et al, 2005;Nugteren, 2010;Ward et al, 2003),…”

Section: Calciummentioning

confidence: 99%

“…The concentrations of Mg leached in water range from non detectable to less than 1000 mg/kg, but commonly do not exceed 50 mg/kg (Iwashita et al, 2005;Moreno et al, 2005). Magnesium in alkaline fly ash is poorly leachable in water (<0.1%, Ward et al, 2003), but the mobility increases up to 4% in acidic fly ash.…”

Section: Magnesiummentioning

confidence: 99%

“…In environmental conditions, reduced S species are generally present in negligible quantities and SO 4 2-is the dominant species (Fruchter et al, 1990). Iwashita et al (2005) and Izquierdo et al (2008) noted that the leached concentrations of S in water are correlated to its concentration in fly ash. With water only, 40-80% of SO 4 2-was removed from alkaline fly ash from Australia, the Netherlands and Spain, whereas up to 90% was removed from acidic fly ash (Nugteren et al, 2001;Querol et al, 2001;Ward et al, 2003).…”

Section: Sulphurmentioning

confidence: 99%

“…There is no substantial difference between acidic and alkaline ash, since B leachability does not depend significantly upon pH over pH 6 (Cox et al, 1978). Rather, the leached levels appear to be controlled by the total concentration in the fly ash (Iwashita et al, 2005). The lower concentrations of B under mildly acidic conditions may be attributed to ligand exchange mechanisms (Jankowski et al, 2004), although much greater leaching rates are achieved when under strongly acidic conditions (Dreesen et al, 1977).…”

Section: Boronmentioning

confidence: 99%

“…The co-precipitation of B with CaCO 3 under alkaline conditions has been also reported to significantly capture B in alkaline fly ash (Iwashita et al, 2005), but this process is unlikely to occur in acidic-natured fly ash .…”

Section: Boronmentioning

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

604

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: Calciummentioning

confidence: 99%

Section: Magnesiummentioning

confidence: 99%

Section: Sulphurmentioning

confidence: 99%

Section: Boronmentioning

confidence: 99%

Section: Boronmentioning

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

604

379

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Investigation into the adsorption of a commercial coupling agent for polymers onto pretreated fly ash filler particles

Velado

Potgieter

Liauw

2013

J of Applied Polymer Sci

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Fly ash can be used as a filler in polymer composite materials. Two fly ash samples (one from the UK, UKFA, and another one from South Africa, SAFA) were washed with water and HCl and compared to investigate their interaction with a commercial coupling agent employed to enhance their incorporation into the polymer matrix. The removal of certain ions from the filler surface resulted in a decrease in the heat of adsorption values due to the reduced number of linkage points for the coupling agent. The coupling agent-filler interaction was possible for some of the metals of the second group (calcium, magnesium, and sodium) and some of the "p" group (aluminum, sulfur, and phosphorous) on the surface of fly ash.

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Effect of fly ash washing conditions on the properties of coupling agent modified polypropylene/fly ash composites

2013

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Two fly ash samples (one from UK, UKFA, and another from South Africa, SAFA) were washed with water and 1 M hydrochloric acid (followed by water) prior to incorporation (at 65% wt) into polypropylene homopolymer, containing an unsaturated carboxylic acid coupling agent (Lubrizol Solplus® C800) with dicumyl peroxide free radical initiator. Melt blending was achieved using a Haake Rheomix 600 mixing chamber, and composite test plaques were compression moulded. Flexural and impact testing was then carried out. Unwashed and water washed fly ash–based composites responded well to C800 modification, and flow microcalorimetry (FMC) and diffuse reflectance Fourier transform infrared spectroscopy studies confirmed strong interaction between C800 and fly ash. However, washing the fly ash with HCl led to a reduction in composite flexural and impact properties. Scanning electron microscopy imaging of the latter composite fracture surfaces revealed poor filler‐matrix adhesion, which was thought to be due to reduced interaction between C800 and HCl washed fly ash. The latter was confirmed using FMC. Reduction of C800/fly ash interaction led to a reduction in the nucleation of polypropylene (PP) crystallization and a decrease in melt flow rate. The latter may be due to a shift in locus of PP–C800 addition reactions from the interfacial region to the bulk matrix. POLYM. COMPOS., 35:698–707, 2014. © 2013 Society of Plastics Engineers

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Leaching characteristics of boron and selenium for various coal fly ashes

Cited by 81 publications

References 17 publications

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

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

Investigation into the adsorption of a commercial coupling agent for polymers onto pretreated fly ash filler particles

Effect of fly ash washing conditions on the properties of coupling agent modified polypropylene/fly ash composites

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