Abstract
This study aimed to describe the adsorption process of ortho-dichlorobenzene (o-DCB) onto activated carbons (ACs) and modified carbon nanotubes (CNTs) from the aqueous phase. The starting material NC_7000 carbon nanotubes were modified by chlorination (NC_C) and then by the introduction of hydroxyl groups (NC_C_B). The concentration of o-DCB in solutions was performed by UV-VIS spectrophotometry. After adsorption, the activated carbons were regenerated by extraction with organic solvents such as acetone, methanol, ethanol, and 1-propanol; the carbon nanotubes were regenerated by methanol. The degree of adsorbate recovery was determined by gas chromatography (GC) with flame ionization detection, using ethylbenzene as an internal standard. The equilibrium isotherm data of adsorption were satisfactorily fitted by the Langmuir equations. The results indicate that carbon adsorbents are effective porous materials for removing o-DCB from the aqueous phase. Additionally, activated carbons are more regenerative adsorbents than carbon nanotubes. The recoveries of o-DCB from ACs were in the range of 76–85%, whereas the recoveries from CNTs were in the range of 23–46%. Modifications of CNTs affect the improvement of their adsorption properties towards o-DCB compared to unmodified CNTs. However, the introduction of new functional groups on carbon nanotube surfaces makes the regeneration process less effective.
Highlights
Compared with other abatement methods, the adsorption process has been recognized as the most effective, especially with carbon materials as an adsorbent
We have examined the adsorbability of o-DCB onto activated carbons and carbon nanotubes from an aqueous solution
Our study shows that activated carbons are a better choice for the adsorption of o-DCB from an aqueous solution than carbon nanotubes
Summary
Compared with other abatement methods, the adsorption process has been recognized as the most effective, especially with carbon materials as an adsorbent. Activated carbon is a microporous adsorbent that is characterized by significant porosity and developed surface area. Their physical and sorption properties depend on the raw material, the method of preparation and activation, as well as the modification of the surface groups [7]. Due to their wide range of properties, activated carbons are ideal for removing substances such as carbon dioxide [8], volatile organic compounds [9], or inorganic ions like copper, zinc, and chromium from a gas or aqueous phase [10]. Many investigations show that nanotubes are effective adsorbents for removing fluoride [11], dioxin [12], or lead [13]
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