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Munonde TS, Nqombolo A, Hobongwana S, Mpupa A, Nomngongo PN. Removal of methylene blue using MnO 2@rGO nanocomposite from textile wastewater: Isotherms, kinetics and thermodynamics studies. Heliyon 2023; 9:e15502. [PMID: 37151643 PMCID: PMC10161714 DOI: 10.1016/j.heliyon.2023.e15502] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 04/06/2023] [Accepted: 04/11/2023] [Indexed: 05/09/2023] Open
Abstract
In this study, the adsorptive removal of methylene blue dye, which is commonly used in textile industries, was investigated using the MnO2@reduced graphene oxide (rGO) adsorbent. The sonication-assisted synthesis from rGO nanosheets and MnO2 nanoparticles resulted to the MnO2@rGO nanocomposite with improved physicochemical properties. The characterization results showed the improved surface area, porous structure and adsorption sites from the nitrogen adsorption-desorption studies, improved morphology from the Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) and the improved crystal structure from X-ray powder diffraction (XRD). The improved physicochemical properties on the MnO2@rGO nanocomposite played a significant role in enhancing the dye removal in textile wastewater. The equilibrium experimental data was best described by the Langmuir isotherm model with a maximum adsorption capacity of 156 mg g-1, suggesting a monolayer adsorption. The kinetic data best fitted the pseudo-second order kinetic model, suggesting a chemisorption adsorption process. The thermodynamic data (ΔG°, ΔH° and ΔS°) confirmed the feasibility, randomness and spontaneous nature of the adsorption process. The mechanism of adsorption involved the hydrogen bonding, π-π interactions and electrostatic interactions. The removal of methylene blue using MnO2@rGO nanocomposite in spiked textile wastewater yielded a 98-99% removal. The method demonstrated competitiveness when compared with literature reported results, paving way for further investigations towards industrial scale applications.
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Affiliation(s)
- Tshimangadzo S. Munonde
- Department of Chemical Sciences, University of Johannesburg, Doornfontein Campus, P.O. Box 17011, Doornfontein, 2028, South Africa
- Department of Science and Innovation-National Research Foundation South African Research Chair Initiative (DSI-NRF SARChI) in Nanotechnology for Water, University of Johannesburg, Doornfontein, 2028, South Africa
| | - Azile Nqombolo
- Department of Chemical Sciences, University of Johannesburg, Doornfontein Campus, P.O. Box 17011, Doornfontein, 2028, South Africa
- Department of Science and Innovation-National Research Foundation South African Research Chair Initiative (DSI-NRF SARChI) in Nanotechnology for Water, University of Johannesburg, Doornfontein, 2028, South Africa
- Department of Chemistry, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
| | - Siphosethu Hobongwana
- Department of Science and Innovation-National Research Foundation South African Research Chair Initiative (DSI-NRF SARChI) in Nanotechnology for Water, University of Johannesburg, Doornfontein, 2028, South Africa
| | - Anele Mpupa
- Department of Chemical Sciences, University of Johannesburg, Doornfontein Campus, P.O. Box 17011, Doornfontein, 2028, South Africa
- Department of Science and Innovation-National Research Foundation South African Research Chair Initiative (DSI-NRF SARChI) in Nanotechnology for Water, University of Johannesburg, Doornfontein, 2028, South Africa
| | - Philiswa Nosizo Nomngongo
- Department of Chemical Sciences, University of Johannesburg, Doornfontein Campus, P.O. Box 17011, Doornfontein, 2028, South Africa
- Department of Science and Innovation-National Research Foundation South African Research Chair Initiative (DSI-NRF SARChI) in Nanotechnology for Water, University of Johannesburg, Doornfontein, 2028, South Africa
- DSI/Mintek Nanotechnology Innovation Centre, University of Johannesburg, Doornfontein, 2028, South Africa
- Corresponding author.Department of Chemical Sciences, University of Johannesburg, Doornfontein Campus, P.O. Box 17011, Doornfontein, 2028, South Africa.
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Liu W, Yang Y, Hu X, Zhang Q, Wang C, Wei J, Xie Z, Zhou Z. Light-Assisted Li-O 2 Batteries with Lowered Bias Voltages by Redox Mediators. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2200334. [PMID: 35678600 DOI: 10.1002/smll.202200334] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 05/23/2022] [Indexed: 06/15/2023]
Abstract
The enormous overpotential caused by sluggish kinetics of the oxygen reduction reaction and the oxygen evolution reaction prevents the practical application of Li-O2 batteries. The recently proposed light-assisted strategy is an effective way to improve round-trip efficiency; however, the high-potential photogenerated holes during the charge would degrade the electrolyte with side reactions and poor cycling performance. Herein, a synergistic interaction between a polyterthiophene photocatalyst and a redox mediator is employed in Li-O2 batteries. During the discharge, the voltage can be compensated by the photovoltage generated on the photoelectrode. Upon the charge with illumination, the photogenerated holes can be consumed by the oxidization of iodide ions, and thus the external circuit voltage is compensated by photogenerated electrons. Accordingly, a smaller bias voltage is needed for the semiconductor to decompose Li2 O2 , and the potential of photogenerated holes decreases. Finally, the round-trip efficiency of the battery reaches 97% with a discharge voltage of 3.10 V and a charge voltage of 3.19 V. The batteries show stable operation up to 150 cycles without increased polarization. This work provides new routes for light-assisted Li-O2 batteries with reduced overpotential and boosted efficiency.
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Affiliation(s)
- Weiwei Liu
- School of Materials Science and Engineering, Institute of New Energy Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (ReCast), Nankai University, Tianjin, 300350, China
| | - Yuting Yang
- School of Materials Science and Engineering, Institute of New Energy Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (ReCast), Nankai University, Tianjin, 300350, China
| | - Xu Hu
- School of Materials Science and Engineering, Institute of New Energy Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (ReCast), Nankai University, Tianjin, 300350, China
| | - Qinming Zhang
- School of Materials Science and Engineering, Institute of New Energy Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (ReCast), Nankai University, Tianjin, 300350, China
| | - Chengyi Wang
- School of Materials Science and Engineering, Institute of New Energy Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (ReCast), Nankai University, Tianjin, 300350, China
| | - Jinping Wei
- School of Materials Science and Engineering, Institute of New Energy Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (ReCast), Nankai University, Tianjin, 300350, China
| | - Zhaojun Xie
- School of Materials Science and Engineering, Institute of New Energy Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Center (ReCast), Nankai University, Tianjin, 300350, China
| | - Zhen Zhou
- Engineering Research Center of Advanced Functional Material Manufacturing of Ministry of Education, School of Chemical Engineering, Zhengzhou University, Zhengzhou, Henan, 450001, China
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Facile synthesis of highly flexible sodium ion conducting polyvinyl alcohol (PVA)-polyethylene glycol (PEG) blend incorporating reduced graphene-oxide (rGO) composites for electrochemical devices application. JOURNAL OF POLYMER RESEARCH 2022. [DOI: 10.1007/s10965-022-02892-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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