Zeolite Synthesized by Alkaline Hydrothermal Treatment of Bottom Ash from Combustion of Municipal Solid Wastes

Abstract

The conversion of bottom ash from fluidized‐bed combustion of municipal solid waste (MSW) to zeolite, by means of alkaline hydrothermal treatment (HT), in 1M NaOH solution, is presented in this work. The transformation of the bottom ash was characterized by X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, surface area (BET‐N2), and scanning electron microscopy (SEM) analyses. As a result of the HT at 100°C, Na6[AlSiO4]6·4H2O, of the structural family of zeolites, together with Ca3AlFe(SiO4)(OH)8, of the structural family of hydrogarnets, began to appear; the surface area of the bottom ash increased 11 times. At 150°C, the amount of Na6[AlSiO4]6·4H2O increased and andradite, hydroxylian (Ca3Fe2(SiO4)3−x(OH)4−x), of the structural family of garnet, was formed. After 200°C of HT, Na6[AlSiO4]6·4H2O was massively formed together with aluminum tobermorite (Ca5Si5Al(OH)O17·5H2O); Ca3AlFe(SiO4)(OH)8 decreased. The surface area of the bottom ash increased 13 times. The conversion of bottom ash in zeolite is considered of great significance, opening new opportunities for stabilization and applications of this type of waste. Zeolite and also the other compounds—aluminum tobermorite, andradite, and Ca3AlFe(SiO4)(OH)8—can substitute a variety of ionic species, which allows the bottom ash to be useful for immobilizing toxic and radioactive wastes. An equivalent study was conducted in water instead of NaOH as a reference.

Adsorption treatment and recovery of the hazardous dye, Brilliant Blue FCF, over bottom ash and de-oiled soya

“…The bands at 3467, 2930, 2676, 1502, 1097 and 790 cm −1 showed the presence of laumonite, amber, mulite, azurite, bavenite and kaolinite [30]. In case of de-oiled soya the bands obtained at 479, 779, 1113, 3459 cm −1 represented gorthite…”

“…The adsorption process was monitored at different temperatures (30,40 and 50 • C) under batch technique. Adsorption isotherms were recorded at a fixed pH (pH range 2.0-7.0) over the concentration range 1 × 10 −5 to 1 × 10 −4 M of BB solutions in a series of 100 ml graduated conical flasks containing 25 ml solution of each concentration.…”

Síntesis hidrotermal de Zeolita a partir de Ceniza Volante tipo F: Influencia de la Temperatura

“…Además, se favorece, desde un punto de vista termodinámico, la formación de fases estables, como es el caso de la fase katoita cúbica (Ca 3 Al 2 (SiO 4 )(OH) 8 ), el gel C-S-H(Ca 1.5 SiO 3.5 .xH 2 O), a-C 2 SH, la tobermorita sustituida por aluminio (Ca 5 Si 5 Al(OH)O 17 ·5H 2 O) y zeolitas tipo A (hidroxi-sodalita) Na 6 [AlSiO 4 ] 6 ·4H 2 O (1-3). Estas fases pueden actuar tanto como precursores de cementos belíti-cos reactivos después de su calentamiento (4-6), como de fases inmovilizadoras de especies tóxicas como el Cs, Cd, Pb y Cr (7)(8).…”

“…Moreover, it favours the formation of stable (thermodynamically speaking) phases such as cubic katoite (Ca 3 Al 2 (SiO 4 )(OH) 8 (1)(2)(3). These phases may act both as reactive belite cement precursors after heating (4-6) and as phases able to immobilize toxic species such as Cs, Cd, Pb and Cr (7)(8).…”

Obtaining zeolites from slags and ashes from a waste combustion plant in an autoclave process

“…Ash from waste incinerators may be used as the starting material for the synthesis of zeolites such as: gismondine or gmelite [17,18] zeolite A and zeolite P [18][19][20][21]. It is also possible to obtain zeolite materials from the waste incineration slag [22] in this way, e.g., tobermorite and hydrated sodium aluminium silicates were obtained that exhibited the BET specific surface area of 22.1 m 2 /g (compared with 4.6 m 2 /g for the starting material).…”