Synthesis of Zeolites from Coal Fly Ash Using Alkaline Fusion and Its Applications in Removing Heavy Metals

Abstract

The article presents studies of the influence of parameters of synthesis modes and alkali concentration on the synthesis of zeolite materials from coal fly ash (CFA). The purpose of the study was to synthesise zeolite materials from CFA using the method of alkaline fusion and to determine the susceptibility of selected heavy-metal ions to removal from solutions in an ion exchange process on a selected mesoporous zeolite. It was found that the crystalline phase of sodalite was dominated in all of the samples synthesized. The specific surface area (SBET) of the samples was evaluated using the standard Brunauer–Emmett–Teller (BET) method using N2 sorption. Crystalline zeolite materials have been used to study the efficiency of removing heavy metals from aqueous solutions of Ni2+, Cd2+ and Pb2+. The adsorption data were analyzed using the Langmuir and Freundlich isotherm model. When comparing the estimated coefficient of determination (r2), it was noticed that the sorption data are more accurately described by the Langmuir isotherm and the pseudo-second-order kinetic model. The results of metal adsorption experiments suggest that the synthesized zeolite material has great potential to be used as an inexpensive and alternative source in the production of adsorbents.

Heat and Mass Transfer in Porous Materials

“…This has become a hot area of research for the development of materials with precisely controlled pores and volume distribution. Recent studies [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ] have focused more on precise control of pore shapes, sizes, and volumes to produce high-performance porous materials. The formation of pores in a material can introduce striking features into the material due to its specific surface-to-volume ratio.…”

High‐Purity Template‐Free Mesoporous Silica Synthesized FROM Coal Fly Ash

“…Alternatively, alkali fusion, often with auxiliary substances like NaOH, CaCO 3 , or NH 4 F, converts insoluble crystalline phases into soluble compounds for subsequent silica extraction [7,12,13] . NaOH utilization in alkali‐fusion has yielded various zeolite phases, including sodalite, analcime, cancrinite, and Na−A (LTA) zeolites [14–16] . It is important to note that aluminium, co‐present in the liquid phase, can be separated from silica by adjusting pH [17–19] …”

“…[7,12,13] NaOH utilization in alkali-fusion has yielded various zeolite phases, including sodalite, analcime, cancrinite, and NaÀ A (LTA) zeolites. [14][15][16] It is important to note that aluminium, co-present in the liquid phase, can be separated from silica by adjusting pH. [17][18][19] The resulting silicate solution serves as the silica source for synthesizing porous materials, with templates such as CTAB (cetyltrimethylammonium bromide), P123 (Pluronic-123), and others often employed in the synthesis process.…”

Application of coal fly ash for trace metal adsorption from wastewater: A review

“…For example, Al-Zboon et al [ 81 ] and Huang et al [ 82 ] modified the chemical properties of CFA with sodium hydroxide and the results revealed its enhanced adsorption properties due to chemical modification. Other CFA-based materials tested to increase the adsorption capacity of CFA include modified zeolites, CFA/C HNCPs, TiO 2 /CFA, ZnO/CFA, CFA-decorated with tungsten oxide-graphene oxide, Mg(OH) 2 /calcined CFA nanocomposite and polyethyleneimine (PEI)/CFA [ 4 , 12 , 45 , 75 , [83] , [84] , [85] , [86] ]. For examples, Tauanov et al [ 85 ] and Mofulatsi et al [ 86 ] have also used a manganese coated zeolite to adsorb Cu (II) and Pb (II) ions and showed that the coating makes the adsorbent more efficient.…”