Two-Dimensional Infrared Correlation Spectroscopy, Conductor-like Screening Model for Real Solvents, and Density Functional Theory Study on the Adsorption Mechanism of Polyvinylpolypyrrolidone for Effective Phenol Removal in an Aqueous Medium
The discharge of industrial effluents, such as phenol, into aquatic and soil environments is a global problem due to its serious negative impacts on human health and aquatic ecosystems. In this study, the ability of polyvinylpolypyrrolidone (PVPP) to remove phenol from an aqueous medium was inve...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Chemical Society (ACS)
2021
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/92447/1/92447_Two-Dimensional%20Infrared%20Correlation%20Spectroscopy.pdf http://irep.iium.edu.my/92447/ https://pubs.acs.org/doi/10.1021/acsomega.1c02699 https://doi.org/10.1021/acsomega.1c02699 |
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| Summary: | The discharge of industrial effluents, such as phenol, into aquatic
and soil environments is a global problem due to its serious negative impacts on
human health and aquatic ecosystems. In this study, the ability of
polyvinylpolypyrrolidone (PVPP) to remove phenol from an aqueous medium
was investigated. The results showed that a significant proportion of phenol (up
to 74.91%) was removed using PVPP at pH 6.5. Isotherm adsorption
experiments of phenol on PVPP indicated that the best-fit adsorption was
obtained using Langmuir models. The response peaks of the hydroxyl groups of
phenol (OH) and the carboxyl groups (i.e., CO) of PVPP were altered,
indicating the formation of a hydrogen bond between the PVPP and phenol
during phenol removal, as characterized using 1D and 2D IR spectroscopy. The
resulting complexes were successfully characterized based on their thermodynamic
properties, Mulliken charge, and electronic transition using the DFT
approach. To clarify the types of interactions taking place in the complex
systems, quantum theory of atoms in molecules (QTAIM) analysis, reduced density gradient noncovalent interaction (RDG-NCI)
approach, and conductor-like screening model for real solvents (COSMO-RS) approach were also successfully calculated. The
results showed that the interactions that occurred in the process of removing phenol by PVPP were through hydrogen bonding
(based on RDG-NCI and COSMO-RS), which was identified as an intermediate type (∇2ρ(r) > 0 and H < 0, QTAIM). To gain a
deeper understanding of how these interactions occurred, further characterization was performed based on adsorption mechanisms
using molecular electrostatic potential, global reactivity, and local reactivity descriptors. The results showed that during hydrogen
bond formation, PVPP acts as a nucleophile, whereas phenol acts as an electrophile and the O9 atom (i.e., donor electron) reacts
with the H22 atom (i.e., acceptor electron). |
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