Immobilization mechanism of Pb in fly ash-based geopolymer

Bin, Guo; Pan, De’an; Liu, Bo; Volinsky, Alex A.; Fincan, Mustafa; Du, Jinfeng; Zhang, Shengen

doi:10.1016/j.conbuildmat.2016.12.139

Cited by 122 publications

(33 citation statements)

References 32 publications

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“…In earlier years, Ordinary Portland Cement (OPC) was considered as the best cementitious material which could effectively solidify the heavy metals by precipitation (due to its high pH) and adsorption reactions [6]. Later on, a new type of cementitious material was also named as alkali-activated cementitious material having superior properties such as great resistance to acid attack, low permeability, great resistance to high temperature and long-term durability, which were introduced for solidification/stabilization purposes [6,7,8,9,10]. Additionally, these cementitious materials were more stable to chloride ions exposure as compared to OPC [11].…”

Section: Introductionmentioning

confidence: 99%

The Solidification of Lead-Zinc Smelting Slag through Bentonite Supported Alkali-Activated Slag Cementitious Material

Mao

Muhammad

et al. 2019

IJERPH

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The proper disposal of Lead-Zinc Smelting Slag (LZSS) having toxic metals is a great challenge for a sustainable environment. In the present study, this challenge was overcome by its solidification/stabilization through alkali-activated cementitious material i.e., Blast Furnace Slag (BFS). The different parameters (water glass modulus, liquid-solid ratio and curing temperature) regarding strength development were optimized through single factor and orthogonal experiments. The LZSS was solidified in samples that had the highest compressive strength (after factor optimization) synthesized with (AASB) and without (AAS) bentonite as an adsorbent material. The results indicated that the highest compressive strength (AAS = 92.89MPa and AASB = 94.57MPa) was observed in samples which were prepared by using a water glass modulus of 1.4, liquid-solid ratio of 0.26 and a curing temperature of 25 °C. The leaching concentrations of Pb and Zn in both methods (sulfuric and nitric acid, and TCLP) had not exceeded the toxicity limits up to 70% addition of LZSS due to a higher compressive strength (>60 MPa) of AAS and AASB samples. While, leaching concentrations in AASB samples were lower than AAS. Conclusively, it was found that the solidification effect depends upon the composition of binder material, type of leaching extractant, nature and concentration of heavy metals in waste. The XRD, FTIR and SEM analyses confirmed that the solidification mechanism was carried out by both physical encapsulation and chemical fixation (dissolved into a crystal structure). Additionally, bentonite as an auxiliary additive significantly improved the solidification/stabilization of LZSS in AASB by enhancing the chemical adsorption capacity of heavy metals.

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Section: Introductionmentioning

confidence: 99%

The Solidification of Lead-Zinc Smelting Slag through Bentonite Supported Alkali-Activated Slag Cementitious Material

Mao

Muhammad

et al. 2019

IJERPH

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“…The stabilisation of metals in geopolymeric matrices could be affected by the chemical properties of the metal compounds. This was proved in the case of Pb (Guo et al 2017) and Cr (Zhang et al 2008b;Chen et al 2016). Three types of the Pb contaminants PbO, PbSO 4 and PbS, common in the environment, were added in the fly ash based geopolymer matrices.…”

Section: The Characteristics Of Heavy Metals and Heavy Metal Formsmentioning

confidence: 88%

“…Pb was proved to be dispersed throughout the geopolymeric matrix in the case of PbO addition, forming leaded geopolymer via Pb-O-Al or/and Pb-O-Si. By contrast, PbS was observed to be segregated from the bulk of the binder (Guo et al 2017). It was concluded that when Pb compounds were supplied in the form soluble in sodium hydroxide solution, the Pb ions would participate in the formation of geopolymer network, stimulating both chemical bonding and physical encapsulation.…”

Section: The Characteristics Of Heavy Metals and Heavy Metal Formsmentioning

confidence: 94%

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Mechanisms of Heavy Metal Immobilisation using Geopolymerisation Techniques – A review

Gowripalan

2018

ACT

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Every year, substantial amount of waste materials containing toxic substances is produced throughout the world, which causes serious damage to the environment and poses threat to human health. Among available techniques of immobilisation of toxic elements in harmful by-products, geopolymerisation is considered as an effective approach to deal with many environmental issues. Geopolymer binders have long been recognised to have great potential in immobilisation of hazardous wastes due to its advantages over Portland cement based binders. A profound knowledge of how hazardous elements are immobilised by geopolymer binders is necessary for achieving effective waste management strategies. This paper provides some important aspects of geopolymer materials regarding the immobilisation mechanisms and factors influencing the immobilisation efficiency, which are necessary to carry out further research on addressing the hazardous waste immobilisation.

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“…Incorporation of PbO was found to increase the mechanical strength of GP while PbSO 4 and PbS have the reverse effect. The % leaching was very low (<1%), but the leached Pb concentration (6-27 mg/L) was higher than the TCLP limit[41].MK and BFS-based GP received less attention than FA-based GP as hosts for highly soluble heavy metal salts. However, some studies will be discussed here.Yunsheng et al investigated solidification of Pb(II) and Cu(II) in GP prepared from (1:1, w:w) MK {0.6, 62.97, 26.91) and BFS {41.7, 34.20, 14.20} using sodium hydroxide and silicate activators.…”

mentioning

confidence: 95%

Solidification Versus Adsorption for Immobilization of Pollutants in Geopolymeric Materials: A Review

El‐Eswed¹

2018

Solidification

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Geopolymer (GP) is a class of three-dimensional aluminosilicate binder, which is superior to Portland cement materials in acid, heat and fire resistance. GP is produced by reacting an aluminosilicate source (metakaolin, fly ash or waste) with an alkali metal hydroxide or silicate. The aim of the present work is to review the latest developments in three lines of research that deal with application of GP in treatment of pollutants. The first "intra-solidification" that involves mixing real waste (containing heavy metal pollutants) with the GP precursors to obtain a high mechanical strength material. The second type of solidification is "inter-solidification" that involves incorporation of heavy metals solutions (as simulation of polluted water) during geopolymerization reaction. The third line of research "adsorption" involves agitating GP with heavy metals solutions and studying the ability of GP to remove heavy metals from water. These techniques will be investigated regarding efficiency and mechanism of immobilization, cost and environmental impact. GPs are strong low-cost adsorbents for heavy metals. In intra-solidification, despite the high mechanical strength of the produced GPcontaining waste, geopolymerization reduces effectively the leaching of heavy metals. The reverse was observed in the case of inter-solidification which presents a greater challenge than intra-solidification.

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Immobilization mechanism of Pb in fly ash-based geopolymer

Cited by 122 publications

References 32 publications

The Solidification of Lead-Zinc Smelting Slag through Bentonite Supported Alkali-Activated Slag Cementitious Material

The Solidification of Lead-Zinc Smelting Slag through Bentonite Supported Alkali-Activated Slag Cementitious Material

Mechanisms of Heavy Metal Immobilisation using Geopolymerisation Techniques – A review

Solidification Versus Adsorption for Immobilization of Pollutants in Geopolymeric Materials: A Review

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