The influence of Pb addition on the properties of fly ash-based geopolymers

Nikolić, Violeta N.; Komljenović, Miroslav; Džunuzović, Nataša; Miladinović, Zoran

doi:10.1016/j.jhazmat.2018.02.023

Cited by 58 publications

(16 citation statements)

References 36 publications

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“…It can be observed that an increase in the concentration of lead nitrate at all curing ages, causes a decrease in the compressive strength of the hardened activated slag paste. This is attributed to the limited diffusion of the dissolved species of lead hydroxide through a network of hardened paste matrix pores and the formation of some structural defect [14]. The addition of NaOH /Na2SiO3 has a positive effect on the compressive strength values, this can be attributed to providing an activated system by silicate group enhance the strength [15].According to Fig.…”

Section: Methods Of Investigationmentioning

confidence: 94%

Effect of Pb+2 ion on physico chemical properties of fly ash -slag geopolymer pastes

Helall

Ahmed

Ragei

2021

Journal of Scientific Research in Science

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The aim of this work is to examine the stabilization or immobilization of heavy metals such as Pb (NO3)2 in a various paste of slag and slag-FA based and on geopolymer pastes. Geopolymer prepared by 100% slag and partially substitution of slag by 15% Fly ash (FA) [85% slag+15%FA]. The alkaline activator is (1:1) liquid sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solution (the concentration of sodium hydroxide is 5 Molar). Different percentages of Pb (NO3)2 were added to the alkali activation mixture, 0.5%, and 1% by mass% of the solid binder. The obtained geopolymer specimens are cured in water for 90 days. The compressive strength test, combined water content, X-ray diffraction (XRD), Atomic absorption, and Transform infrared spectrometry (FTIR) are examined. The results showed that the used lead nitrate caused a retarding effect for the hydration of the investigated geopolymer mixes.The best mix for immobilization were 99.98% in mix SF1[85%slag+15%Fly ash +0.5%Pb +2 ].

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Section: Methods Of Investigationmentioning

confidence: 94%

Effect of Pb+2 ion on physico chemical properties of fly ash -slag geopolymer pastes

Helall

Ahmed

Ragei

2021

Journal of Scientific Research in Science

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“…The potential use of FA-based geopolymers as immobilization matrices for heavy metals and radionuclides was previously studied by several research groups [6][7][8][9][10][11]. The negatively-charged alumina groups within the alumino-silicate backbone of the geopolymer serve as cation binding sites, facilitating their immobilization.…”

Section: Introductionmentioning

confidence: 99%

Alkali Activation of Fly Ash in the Presence of Sodium Nitrate

Ofer-Rozovsky

Bar-Nes²,

Katz

et al. 2021

Preprint

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The use of fly ash as a precursor for geopolymer has been investigated during the last decades for various applications. The aim of this research was to study the effect of nitrate on the formation and evolution of fly ash-based geopolymers, in order to assess their applicability as waste immobilization matrices. These may be of interest in order to treat waste streams from agricultural runoff and various industries including the nuclear industry. Fly ash was alkali-activated using NaOH solutions of various alkalinities, to which nitrates were added as NaNO3. The samples were cured at 40֯C for different periods and characterized by X-Ray diffractometry, Fourier transform mid-Infrared spectroscopy, scanning electron microscopy (SEM), and compressive strength measurements. The content of neo-formed crystalline phases in fly ash-based geopolymers was found to be lower than in metakaolin-based systems studied previously. The nature of the minerals formed in nitrate-free samples differed from those obtained in corresponding metakaolin-based geopolymers. Nevertheless, the dominant phase formed in the presence of nitrate at sufficiently high alkalinity was nitrate-cancrinite, as reported for metakaolin-based geopolymers, regardless of the type of fly-ash used. Although the presence of nitrates was found to have a promoting effect on the geopolymerization process of metakaolin-based geopolymers, it was found to inhibit the processes in fly-ash-based geopolymers.The formation of crystalline phases in FA-based geopolymers suggests that these materials may be used for immobilizing various hazardous species, while FA-based geopolymers containing the nitrate-cancrinite can be considered as a promising candidate for immobilizing radionuclides from radioactive wastes.

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