Zeolite development from fly ash and utilization in lignite mine-water treatment

Abstract

Materials and methods.Fly ash from two lignite-fed power stations of Greece has been utilized as raw material to synthesize zeolitic materials with upgraded adsorption capacity. Two different siliceous fly ash samples (barely Class C -ASTM C618) underwent hydrothermal treatment at fixed solid / liquid ratio (50 g FA / 1 L NaOH) and constant temperature (90°C). The zeolitic products have been characterized for their microstructure, chemical, and mineralogical composition by means of SEM, FAAS, and XRD, respectively. In light of their prospective utilization as liquid-phase sorbents, the specific surface area & porosity of samples were also determined by means of N 2 -porosimetry.Results and discussion. Various types of Na-zeolites have been identified as the predominant phases in the synthetic materials. Selected zeolitic samples were tested for their actual heavy metal-removal capacity by water sampled from lignite mines in Northern Greece. Artificial aquatic samples with known concentration of heavy metals were also used, showing that the synthetic zeolitic materials are able to uptake a wide variety of potential pollutants with up to 100% efficiency. Conclusions.The synthetic zeolitic materials were tested comparatively, showing that the more intense the zeolitic presence in the synthetic materials, the greater the uptake rates for certain groups of trace elements. 113

Reduction of Toxic Element Mobility in Mining Soil by Zeolitic Amendments

“…The CFA was converted to synthetic zeolitic material (FAZ) via a low temperature alkaline hydrothermal treatment with 1M NaOH. The hydrothermal treatment, proposed by Koukouzas et al (2010) and Itskos et al (2015) took place at 90-100 0 C. The zeolite produced was Na-P1(Na6Al6Si10O32·12H2O), a synthetic mineral with high ion exchange capacity due to the substitution of Si (IV) by Al (III) in its structure, which results in an increased overall negative charge. Heavily contaminated soil samples (LSoil) were collected near the Lavrion harbor, (Figure 1).…”

“…The fly ash low temperature hydrothermal zeolitization processes implemented in the present study, are based on the chemical attack of Al-Si bearing phases of the fly ash by alkaline solutions and the subsequent transformation to zeolitic material (Querol et al, 2002;Mouhtaris et al, 2003;Koukouzas et al, 2010 andItskos et al, 2015). Products of such transformation have been described by better ion-exchange properties and several fold-enlarged surfaces (Remenarova et al, 2014 andGiannatou et al, 2015).…”

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“…The main effort to minimize the impacts of the disposal of these residues in the environment must be a search for enlarging potentialities for their use (Itskos et al, 2015).…”

Improved removal of Cr(VI) from aqueous solution using zeolite synthesized from coal fly ash via mechano‐chemical treatment

“…Synthesized zeolites can be widely employed in environmental protection and agriculture because of their high specific surface areas, high thermal stabilities, excellent catalytic characteristics, and superb adsorption and ion exchange capacities . There are generally three approaches for synthesizing zeolites from coal fly ash including (1) alkali fusion method, (2) hydrothermal process, and (3) the combination of alkali fusion and hydrothermal treatment, which is shown in Table . The first is called ‘alkali fusion method’, in which water is injected into a hot (e.g.…”