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Liu X, Wu W, Lin D, Yang K. Linear adsorption of organic compounds on mesoporous activated carbon in bi-solute system. Heliyon 2024; 10:e25729. [PMID: 38352802 PMCID: PMC10862680 DOI: 10.1016/j.heliyon.2024.e25729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 01/25/2024] [Accepted: 02/01/2024] [Indexed: 02/16/2024] Open
Abstract
Knowledge of organic compounds adsorption by adsorbents is essential for evaluating the environmental fates of organic compounds and removing them from the environment. Linear adsorption, as a supplement to the traditionally nonlinear adsorption, was previously proposed for the linear sorption of organic compounds on the mesoporous surface of carbon nanotubes (CNTs) in multi-solute system. However, CNTs are not the ideal adsorbent to verify the linear adsorption mechanism, because of their partition-like phase components such as mobile graphene layers that could be responsible for the linear sorption through linear partition mechanism instead, and thus the linear adsorption theory was argued. In this study, therefore, mesoporous activated carbon (MAC), widely accepted as the model free of partition phase components, was selected as an adsorbent to investigate the adsorption of typical organic compounds in the bi-solute system for verifying whether the linear adsorption phenomenon existed or not. The isotherm of nitrobenzene on MAC was changed from nonlinear to linear with 4-nitrophenol up to 1400 mg/L, and the linear isotherm slope decreased more as 4-nitrophenol concentration increased until 4000 mg/L. It agreed with the characteristics of adsorption (i.e., competition) but not partition (i.e., noncompetition), confirming the existence of linear adsorption. The isotherm linearity was attributed to the reduction of adsorption interactions by displacement and multilayer adsorption. Moreover, linear adsorption of apolar compounds on MAC could occur with apolar or polar competitors, while for polar compounds, linear adsorption could occur with only polar competitors. The observed linear sorption and the competition of organic compounds in the bi-solute system on MAC free of partition phase components verified that the linear adsorption existed, which gives a new insight into the adsorption theory for organic compounds. The results could provide better fundamental theory of adsorption for improving the accuracy of environmental risk assessment of organic pollution and enhancing the efficiency of organic pollution control in the environment.
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Affiliation(s)
- Xiaoyu Liu
- Department of Environmental Science, Zhejiang University, Hangzhou, 310058, China
- Key Laboratory of Environmental Pollution and Ecological Health of Ministry of Education, Hangzhou, 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, 310058, China
| | - Wenhao Wu
- Department of Environmental Science, Zhejiang University, Hangzhou, 310058, China
- Key Laboratory of Environmental Pollution and Ecological Health of Ministry of Education, Hangzhou, 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, 310058, China
| | - Daohui Lin
- Department of Environmental Science, Zhejiang University, Hangzhou, 310058, China
- Key Laboratory of Environmental Pollution and Ecological Health of Ministry of Education, Hangzhou, 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, 310058, China
| | - Kun Yang
- Department of Environmental Science, Zhejiang University, Hangzhou, 310058, China
- Zhejiang University-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, 311200, China
- Key Laboratory of Environmental Pollution and Ecological Health of Ministry of Education, Hangzhou, 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, 310058, China
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Wen J, Liu Z, Xi H, Huang B. Synthesis of hierarchical porous carbon with high surface area by chemical activation of (NH 4) 2C 2O 4 modified hydrochar for chlorobenzene adsorption. J Environ Sci (China) 2023; 126:123-137. [PMID: 36503742 DOI: 10.1016/j.jes.2022.04.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 06/17/2023]
Abstract
In this work, hydrothermal technique combined with KOH activation were employed to develop a series of porous carbons (NPCK-x) using tobacco stem as a low-cost carbon source and (NH4)2C2O4 as a novel nitrogen-doping agent. Physicochemical properties of NPCK-x were characterized by Brunauer-Emmett-Teller, field emission scanning electron microscopy, X-ray diffraction, Raman microscope, elemental analysis, and X-ray photoelectron spectroscopy. Results showed that the NPCK-x samples possessed large surface areas (maximum: 2875 m2/g), hierarchical porous structures, and high degree of disorder. N-containing functional groups decomposed during activation process, which could be the dominant reason for appearance of abundant mesopores and well-developed pore structure. Dynamic chlorobenzene adsorption experiments demonstrated that carbon materials with (NH4)2C2O4 modification exhibited higher adsorption capacity (maximum: 1053 mg/g) than those without modification (maximum: 723 mg/g). The reusability studies of chlorobenzene indicated that the desorption efficiency of (NH4)2C2O4 modified porous carbon reached 90.40% after thermal desorption at 100°C under N2 atmosphere. Thomas model fitting results exhibited that the existence of mesopores accelerated the diffusion rate of chlorobenzene in porous carbon. Moreover, Grand Canonical Monte Carlo simulation was conducted to verify that micropores with pore sizes of 1.2-2 nm of the optimized porous carbon were the best adsorption sites for chlorobenzene and mesopores with pore sizes of 2-5 nm were also highly active sites for chlorobenzene adsorption.
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Affiliation(s)
- Jie Wen
- School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006, China
| | - Zewei Liu
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Hongxia Xi
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China
| | - Bichun Huang
- School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006, China.
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