Synthesis of the Sodalite by Geopolymerization Process Using Coal Fly Ash

Abstract

IntroductionGeopolymers, also called inorganic polymers, are classified as synthetic aluminosilicate materials characterized by many interesting properties. This group of materials has gained a lot of attention in the past 10 years (measured by increasing number of publications) and raised high expectations concerning their applicability. Geopolymers are usually hard, mechanically resistant materials, therefore many attempts to substitute Portland cement in the construction industry have been taken [1]. Despite the huge number of publications devoted to this family and hundreds of new examples of these materials, researching them is still pioneering [2]. Attempts to systematize their structures and properties are just beginning to appear.Geopolymers are considered as zeolite precursors, thus zeolites are often detected in geopolymer gels. Activation of metakaolinite with sodium silicate and sodium hydroxide solutions at various temperatures (20-100ºC) can lead to the geopolymer-zeolite hybrid materials containing zeolite A, sodalite, and zeolite Y [3]. During hydrothermal treatment at low temperature, depending on the synthesis conditions, metakaolin-based geopolymeric gel transforms into zeolite ZSM-20, zeolite Na-P1, faujasite, sodalite, and analcime [4]. Metakaolin-based geopolymeric gel was also used for hydrothermal preparation of a faujasite zeolite membrane for alcohol/water separation [5]. On the other hand, non-hydrothermal preparation of Na-A zeolite membranes from chemosynthetic Al 2 O 3 -SiO 2 powder and sodium silicate solution by the geopolymer gel thermal conversion at 60ºC is possible [6].Pol. J. Environ. Stud. Vol. 26, No. 6 (2017), 2611-2617 AbstractThis study investigated the influence of alkali activation process conditions on the amount and types of zeolites in the resultant geopolymers. The products were formed during the alkaline activation of coal fly ash with the use of aluminium and sodium hydroxide solution. Geopolymers were cured at 80ºC for 24 h. The effects of reaction systems' constitution (expressed as SiO 2 /Al 2 O 3 and Al 2 O 3 /Na 2 O molar ratios) on the phase composition and structure of obtained products were determined. The results indicated that the products obtained from such hydrothermal treatment demonstrated the characteristics of zeolite-like materials -sodalite. By using the appropriate composition of the initial solution (sufficiently high concentration of NaOH and aluminum carrier), it is possible to synthesize the sodalite phase efficiently in an amorphous matrix.

Study on the synthesis mechanism of sodalite, gismondine, and zeolite-P1 zeolite materials from ladle furnace slag and fly ash

“…Compared with GEO, two additional vibration peaks were observed in the ZEO spectrum after hydrothermal treatment. These were the vibration peak at 874 cm −1 , which was the stretching vibration of Si–O–Si, and the symmetric stretching of zeolite tetrahedron at 712 cm −1 , which is one of the characteristic peaks of zeolite molecular sieves 13 , 37 . At the same time, it was observed that after hydrothermal treatment, the peak at 984 cm −1 shifted to 996 cm −1 , which was caused by the increasing degree of active aluminum cross-linking and the degree of silico-aluminate gel polymerization 38 .…”

Avaliação das propriedades de argamassas cimentícias com adição de resíduos da geração termoelétrica

“…De acordo com a intensidade dos picos, verifica-se que o quartzo é mais frequente, seguido de mulita e hematita. Esta mineralogia também foi evidenciada por KRÓL et al [40] e por AZEVEDO et al [41]. Mesmo sendo de locais distintos, observou-se semelhanças entre os difratogramas principalmente no halo amorfo e no pico de quartzo que fica entre 26° e 27º [38][39][40][41].…”

“…Esta mineralogia também foi evidenciada por KRÓL et al [40] e por AZEVEDO et al [41]. Mesmo sendo de locais distintos, observou-se semelhanças entre os difratogramas principalmente no halo amorfo e no pico de quartzo que fica entre 26° e 27º [38][39][40][41]. A formação da mulita, identificada somente por DRX, está relacionada com a combustão do carvão em temperaturas maiores do que 1050°C.…”

Effect of Activating Solution Modulus on the Synthesis of Sustainable Geopolymer Binders Using Spent Oil Bleaching Earths as Precursor

“…It can be observed that the Si-O-T (T:Si or Al) stretching vibration, centered on the precursor at 1035 cm −1 , shifted to lower frequencies in the geopolymers (1004-994 cm −1 ). This change also indicates that the geopolymerization reaction has taken place due to the activation of the amorphous phase of the SOBE residue with the formation of N-A-S-H aluminosilicate gel, which means the condensation of Si-O tetrahedra as well as SiO 4 and AlO 4 in the geopolymer [40,[68][69][70]. The band shift at lower frequencies may be due to an increase in the content of non-bridging oxygens, as well as to an increase in the amount of tetrahedral aluminum in the gel structure [27,71].…”