Optimization and mechanistic insight of phenol removal using an effective green kaolin adsorbent through experimental and computational approaches
The discharge of phenols into the aquatic environment has detrimentally affected human health and the aquatic ecosystem. Hence, removing phenols from polluted water bodies has been a global concern. In this study, a natural and low-cost adsorbent, kaolin, was used to remove phenol from aqueous solut...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English English |
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Elsevier Ltd
2024
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| Online Access: | http://umpir.ump.edu.my/id/eprint/42030/ http://umpir.ump.edu.my/id/eprint/42030/1/Optimization%20and%20mechanistic%20insight%20of%20phenol%20removal_ABST.pdf http://umpir.ump.edu.my/id/eprint/42030/2/Optimization%20and%20mechanistic%20insight%20of%20phenol%20removal.pdf |
| _version_ | 1848826500064739328 |
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| author | Aisyah, Zubir Erna Normaya, Abdullah Nurul Huda, Zuhaidi Goh, Pei Sean Mohd Bijarimi, Mat Piah Mohamad Wafiuddin, Ismail Show, Pau Loke Ahmad Fauzi, Ismail Mohammad Norazmi, Ahmad |
| author_facet | Aisyah, Zubir Erna Normaya, Abdullah Nurul Huda, Zuhaidi Goh, Pei Sean Mohd Bijarimi, Mat Piah Mohamad Wafiuddin, Ismail Show, Pau Loke Ahmad Fauzi, Ismail Mohammad Norazmi, Ahmad |
| author_sort | Aisyah, Zubir |
| building | UMP Institutional Repository |
| collection | Online Access |
| description | The discharge of phenols into the aquatic environment has detrimentally affected human health and the aquatic ecosystem. Hence, removing phenols from polluted water bodies has been a global concern. In this study, a natural and low-cost adsorbent, kaolin, was used to remove phenol from aqueous solutions. Experimental and computational approaches were applied to optimize the removal efficiency and provide mechanistic insight into the phenol removal process. Based on the response surface methodology findings, the optimum conditions were pH 1.6, 40 min, 50 mg/L, and 2 g with 92.19 % maximum percentage removal. The regeneration test shows that kaolin retained over 76.76 % of adsorption capacities. SEM and FESEM reveals the surface morphology and effectiveness of kaolin as phenol removal. The best fit for the Isotherm adsorption for the phenol on kaolin is Freundlich isotherm, which indicated multilayer adsorption. The hydroxyl group from phenol (-OH) and the siloxane group of kaolin (Si-O-Si) shifted, suggesting the presence of a hydrogen bond between kaolin and phenol during adsorption, as determined by one- and two-dimensional IR spectroscopy. Density functional theory calculations were used to support the experimental results by providing information on the Mulliken charge and electronic transition of the complex to improve understanding of the adsorption of phenol on kaolin. Based on the quantum theory of atoms in molecules analysis (QTAIM) and the reduced density gradient non-covalent interaction (RDG-NCI) technique, the chemical reaction occurring during the removal of phenol by kaolin was determined to occur through hydrogen bonding and classified as an intermediate type (∇2ρ(r) > 0 and H < 0). Further characterizations employing molecular electrostatic potential, global reactivity, and local reactivity descriptors were conducted to investigate the mechanism of the phenol adsorption on kaolin. The findings demonstrated that phenol functions as an electrophile while kaolin acts as a nucleophile during the formation of hydrogen bonds, where the interaction occurred between the O2 atom of kaolin (electron donor) and the H13 atom of phenol (electron acceptor). |
| first_indexed | 2025-11-15T03:45:48Z |
| format | Article |
| id | ump-42030 |
| institution | Universiti Malaysia Pahang |
| institution_category | Local University |
| language | English English |
| last_indexed | 2025-11-15T03:45:48Z |
| publishDate | 2024 |
| publisher | Elsevier Ltd |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | ump-420302024-07-22T04:31:41Z http://umpir.ump.edu.my/id/eprint/42030/ Optimization and mechanistic insight of phenol removal using an effective green kaolin adsorbent through experimental and computational approaches Aisyah, Zubir Erna Normaya, Abdullah Nurul Huda, Zuhaidi Goh, Pei Sean Mohd Bijarimi, Mat Piah Mohamad Wafiuddin, Ismail Show, Pau Loke Ahmad Fauzi, Ismail Mohammad Norazmi, Ahmad TP Chemical technology The discharge of phenols into the aquatic environment has detrimentally affected human health and the aquatic ecosystem. Hence, removing phenols from polluted water bodies has been a global concern. In this study, a natural and low-cost adsorbent, kaolin, was used to remove phenol from aqueous solutions. Experimental and computational approaches were applied to optimize the removal efficiency and provide mechanistic insight into the phenol removal process. Based on the response surface methodology findings, the optimum conditions were pH 1.6, 40 min, 50 mg/L, and 2 g with 92.19 % maximum percentage removal. The regeneration test shows that kaolin retained over 76.76 % of adsorption capacities. SEM and FESEM reveals the surface morphology and effectiveness of kaolin as phenol removal. The best fit for the Isotherm adsorption for the phenol on kaolin is Freundlich isotherm, which indicated multilayer adsorption. The hydroxyl group from phenol (-OH) and the siloxane group of kaolin (Si-O-Si) shifted, suggesting the presence of a hydrogen bond between kaolin and phenol during adsorption, as determined by one- and two-dimensional IR spectroscopy. Density functional theory calculations were used to support the experimental results by providing information on the Mulliken charge and electronic transition of the complex to improve understanding of the adsorption of phenol on kaolin. Based on the quantum theory of atoms in molecules analysis (QTAIM) and the reduced density gradient non-covalent interaction (RDG-NCI) technique, the chemical reaction occurring during the removal of phenol by kaolin was determined to occur through hydrogen bonding and classified as an intermediate type (∇2ρ(r) > 0 and H < 0). Further characterizations employing molecular electrostatic potential, global reactivity, and local reactivity descriptors were conducted to investigate the mechanism of the phenol adsorption on kaolin. The findings demonstrated that phenol functions as an electrophile while kaolin acts as a nucleophile during the formation of hydrogen bonds, where the interaction occurred between the O2 atom of kaolin (electron donor) and the H13 atom of phenol (electron acceptor). Elsevier Ltd 2024-07-05 Article PeerReviewed pdf en http://umpir.ump.edu.my/id/eprint/42030/1/Optimization%20and%20mechanistic%20insight%20of%20phenol%20removal_ABST.pdf pdf en http://umpir.ump.edu.my/id/eprint/42030/2/Optimization%20and%20mechanistic%20insight%20of%20phenol%20removal.pdf Aisyah, Zubir and Erna Normaya, Abdullah and Nurul Huda, Zuhaidi and Goh, Pei Sean and Mohd Bijarimi, Mat Piah and Mohamad Wafiuddin, Ismail and Show, Pau Loke and Ahmad Fauzi, Ismail and Mohammad Norazmi, Ahmad (2024) Optimization and mechanistic insight of phenol removal using an effective green kaolin adsorbent through experimental and computational approaches. Journal of Molecular Structure, 1318 (2). pp. 1-16. ISSN 0022-2860. (Published) https://doi.org/10.1016/j.molstruc.2024.139219 https://doi.org/10.1016/j.molstruc.2024.139219 |
| spellingShingle | TP Chemical technology Aisyah, Zubir Erna Normaya, Abdullah Nurul Huda, Zuhaidi Goh, Pei Sean Mohd Bijarimi, Mat Piah Mohamad Wafiuddin, Ismail Show, Pau Loke Ahmad Fauzi, Ismail Mohammad Norazmi, Ahmad Optimization and mechanistic insight of phenol removal using an effective green kaolin adsorbent through experimental and computational approaches |
| title | Optimization and mechanistic insight of phenol removal using an effective green kaolin adsorbent through experimental and computational approaches |
| title_full | Optimization and mechanistic insight of phenol removal using an effective green kaolin adsorbent through experimental and computational approaches |
| title_fullStr | Optimization and mechanistic insight of phenol removal using an effective green kaolin adsorbent through experimental and computational approaches |
| title_full_unstemmed | Optimization and mechanistic insight of phenol removal using an effective green kaolin adsorbent through experimental and computational approaches |
| title_short | Optimization and mechanistic insight of phenol removal using an effective green kaolin adsorbent through experimental and computational approaches |
| title_sort | optimization and mechanistic insight of phenol removal using an effective green kaolin adsorbent through experimental and computational approaches |
| topic | TP Chemical technology |
| url | http://umpir.ump.edu.my/id/eprint/42030/ http://umpir.ump.edu.my/id/eprint/42030/ http://umpir.ump.edu.my/id/eprint/42030/ http://umpir.ump.edu.my/id/eprint/42030/1/Optimization%20and%20mechanistic%20insight%20of%20phenol%20removal_ABST.pdf http://umpir.ump.edu.my/id/eprint/42030/2/Optimization%20and%20mechanistic%20insight%20of%20phenol%20removal.pdf |