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Coal Fly Ash slag and Slag based Geopolymer as An Absorbent for The Removal of Methylene Blue in Wastewater
Coal Fly Ash slag and Slag based Geopolymer as An Absorbent for The Removal of Methylene Blue in Wastewater
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Date
2022
Authors
Nguyễn Đăng Khoa
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Research Projects
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Abstract
The fly ash and slag from coal burning were attractive byproducts to prepare geopolymers for the
adsorption of methyelen blue in wastewater due to their availability and low cost. Various mixing
amounts between them were conducted during geopolymerization with a Na2SiO3/NaOH ratio of
10 M of 2.5 and a curing temperature of 60◦C for 24 h. When the amount of coal slag in the geopolymer
composition was increased from 0 to 51 %, the surface structures of the resultant geopolymers
were much softer and more porous due to the lack of initial material, causing a reduction in the surface
area of geopolymers to 119,23 m2/g for 0 % and 5,29 m2/g for 51 %. The adsorption amount
of methylene blue performed at pH 12 showed different tendencies on the dependence of contact
time for the indivually prepared geopolymer. The uptake amount decreased from 36.2 mg/g to 34.2
mg/g with the enhancement of coal slag in the geopolymer from 0 to 51 % after 180 minutes of
immersion in methylene blue solution. In addition, the adsorption mechanism evaluated by FT-IR
spectroscopy was observed to involve electrostatic forces formed by hydrogen bonding between
hydroxyl groups (Si–OH) and nitrogen atoms in the structure of methylene molecules. This study
indicated that coal slag could be a potential material to prepare geopolymers for removing dye
pollutants.
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Keywords
adsorption,
coal fly ash,
coal slag,
geopolymer,
methylene blue