Abstract
The desorption efficiency (DE) of phenols, including p-nitrophenol, p-chlorophenol, p-hydroxybenzoic acid, phenol, and hydroquinone, from activated carbons (ACs), has been investigated with a variety of solvents to gain insight into the feasibility and mechanism of phenols desorption. Ultrasound (US), microwaves (MW), and flow mode have been used to facilitate phenols desorption. It was found that the basicity, polarity, and hydrogen bonds of solvents synergistically affected phenols desorption. The preferred solvents (Lewis basic solvents, acetic acid, and alcohols) gave highly efficient elution. Increasing the alkaline or/and hydrogen bonding interactions, by adding ammonia or urea, enhanced desorption in most solvents. Moreover, although US and MW heating slightly improved desorption, complete desorption was easily achieved in a flow mode. It is demonstrated, herein, that phenols adsorption on the ACs is a reversible physical process, thus proving the feasibility of phenols desorption with proper solvents. Comparison of diffuse reflectance infrared Fourier transform (DRIFT) spectra and porosity property measurements of pristine, loaded, and eluted ACs confirmed our results. It can, therefore, be stated that our procedure can be used to dispose of secondary pollution while cutting post-treatment costs, thanks to the recovery of valuable compounds and AC recycling.
Highlights
Phenolic compounds have been extensively produced and used worldwide, resulting in a large amount of phenolic discharge and their widespread occurrence in the environment. While they are typical organic pollutants, phenols have attracted specific attention due to their high hydrophilicity, toxicity, and persistence.[1−4] phenols have been frequently used as model compounds for the development of wastewater treatment technology
This study aims to achieve high desorption efficiency (DE) and gain a better understanding of the desorption mechanism involved
We investigated different eluents (MeOH, EtOH, and NaOH), eluent volume, and desorption temperature on the desorption of PNP from Coconut-derived powdered AC (CPAC)
Summary
Phenolic compounds have been extensively produced and used worldwide, resulting in a large amount of phenolic discharge and their widespread occurrence in the environment. Comparison of DRIFT Spectra of Pristine, Loaded, and Eluted ACs. The adsorption and desorption mechanisms of phenols can be further explained by DRIFT spectra analysis of pristine, various loaded, and eluted WPACs. The DRIFT spectra of WPAC samples are compared and shown in Figure S3 of the Supporting Information.
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