Abstract
In this study, spent activated carbons (ACs) were collected from a waste water treatment plant (WWTP) in Incheon, South Korea, and regenerated by heat treatment and KOH chemical activation. The specific surface area of spent AC was 680 m2/g, and increased up to 710 m2/g through heat treatment. When the spent AC was activated by the chemical agent potassium hydroxide (KOH), the surface area increased to 1380 m2/g. The chemically activated ACs were also washed with acetic acid (CH3COOH) to compare the effect of ash removal during KOH activation. The low temperature N2 adsorption was utilized to measure the specific surface areas and pore size distributions of regenerated ACs by heat treatment and chemical activation. The functional groups and adsorbed materials on ACs were also analyzed by X-ray photoelectron spectroscopy and X-ray fluorescence. The generated ash was confirmed by proximate analysis and elementary analysis. The regenerated ACs were tested for toluene adsorption, and their capacities were compared with commercial ACs. The toluene adsorption capacity of regenerated ACs was higher than commercial ACs. Therefore, it is a research to create high value-added products using the waste.
Highlights
Activated carbons (ACs) have been widely used for the water treatment process, which includes the removal of odors, heavy metals, and organic compounds
The spent activated carbons (S-ACs) from waste water treatment plants (WWTP) were regenerated by heat treatment and KOH
The specific surface area was increased by thermal regeneration (H-AC), but it was highly increased using the chemical activation (C-AC)
Summary
Activated carbons (ACs) have been widely used for the water treatment process, which includes the removal of odors, heavy metals, and organic compounds. Thermal regeneration of spent ACs usually results in a lower carbon yield and ash generation [15]. This in turn leads to a negative effect of AC regeneration. Ashes are generated during the thermal treatment which usually block the pores and covers the carbon surface [16]. Increased surface area of spent ACs using thermal regeneration was highly dependent on the adsorbed materials on the carbon surface and reaction conditions. Previous research has investigated the chemical regeneration of spent ACs using the reaction between chemical and adsorbed materials [18], but the chemical activation carried out in this study used the reaction between chemical agent and surface carbons at the high temperature. The regeneration of ACs with high surface areas is to create high value-added products using the waste
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