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Electrochemical Study of Semiconductor Properties for Bismuth Silicate-Based Photocatalysts Obtained via Hydro-/Solvothermal Approach. MATERIALS 2022; 15:ma15124099. [PMID: 35744158 PMCID: PMC9229303 DOI: 10.3390/ma15124099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 05/30/2022] [Accepted: 06/07/2022] [Indexed: 02/01/2023]
Abstract
Three bismuth silicate-based photocatalysts (composites of Bi2SiO5 and Bi12SiO20) prepared via the hydro-/solvothermal approach were studied using electrochemical methods. The characteristic parameters of semiconductors, such as flat band potential, donor density, and mobility of their charge carriers, were obtained and compared with the materials’ photocatalytic activity. An attempt was made to study the effect of solution components on the semiconductor/liquid interface (SLI). In particular, the Mott–Schottky characterization was made in a common model electrolyte (Na2SO4) and with the addition of glycerol as a model organic compound for photocatalysis. Thus, a medium close to those in photocatalytic experiments was simulated, at least within the limits allowed by electrochemical measurements. Zeta-potential measurements and electrochemical impedance spectroscopy were used to reveal the processes taking place at the SLI. It was found that the medium in which measurements were carried out dramatically impacted the results. The flat band potential values (Efb) obtained via the Mott–Schottky technique were shown to differ significantly depending on the solution used in the experiment, which is explained by different processes taking place at the SLI. A strong influence of specific adsorption of commonly used sulfate ions and neutral molecules on the measured values of Efb was shown.
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Treatment of real industrial wastewater with high sulfate concentrations using modified Jordanian kaolin sorbent: batch and modelling studies. Heliyon 2021; 7:e08351. [PMID: 34825080 PMCID: PMC8605197 DOI: 10.1016/j.heliyon.2021.e08351] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/25/2021] [Accepted: 11/05/2021] [Indexed: 11/28/2022] Open
Abstract
In the present study, BaCl2 modified Jordanian kaolin sorbent (obtained from Mahis, Jordan) was used to remove sulfate-contaminated industrial wastewater. The kaolin sample was pretreated to enhance its adsorption capacity and then characterized using X-Ray fluorescence (XRF) and Fourier Transform Infrared Spectroscopy (FTIR). Equilibrium isotherms for the adsorption parameters were carried out experimentally, and the adsorption data correlated very well with Freundlich and Temkin and Dubinin-Radushkevich models. Furthermore, the adsorption kinetics followed the pseudo-first-order and intraparticle diffusion models perfectly. The estimated value of the maximum adsorption capacity qm = 85.08 mg/g indicates that kaolin has a very high capacity to adsorb sulfate ions at studied parameters. The estimated value of the mean free energy (4.87 kJ/mol) is very low, confirming physical type adsorption. The study results established that modified Jordanian kaolin could serve as a safe and effective natural adsorbent for sulfate-contaminated industrial wastewater.
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Sadeghalvad B, Khorshidi N, Azadmehr A, Sillanpää M. Sorption, mechanism, and behavior of sulfate on various adsorbents: A critical review. CHEMOSPHERE 2021; 263:128064. [PMID: 33297069 DOI: 10.1016/j.chemosphere.2020.128064] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/17/2020] [Accepted: 08/19/2020] [Indexed: 06/12/2023]
Abstract
Sulfate decontamination has drawn widespread attention due to its harmful effects by broad human and animal exposure in recent decades. Adsorption is one of the most promising methods for sulfate decontamination. This review categorized various sulfate adsorbents, discussed the adsorption behavior, and introduced effective adsorbents in detail in terms of their preparation, characterization, and affecting factors on adsorption efficiency. Moreover, adsorption mechanisms of sulfate on different adsorbents are reviewed based on the intermolecular interaction, equilibrium, thermodynamic, and kinetic studies. Among natural bioadsorbents, synthesized-organic, and synthesized-inorganic adsorbents chitin-based shrimp shells (156 mg/g), bagasse pith cellulose-based (526.32 mg/g), and ZrO(OH)2/Y-Zeolite (284.22 mg/g) showed the significant capacity for sulfate uptake from aqueous solution, respectively. Although natural adsorbents have been proved to be inexpensive and efficient, they are not as popular as synthesized adsorbents for sulfate decontamination in recent years due to their low recoverability and reusability. The adsorption mechanism of sulfate to various adsorbents is generally attributed to electrostatic interactions, covalent or ionic bonding, and hydrogen bonding. Based on equilibrium studies, sulfate adsorption processes were done mainly homogeneously for most of the adsorbents; however, there are some exceptions of the heterogeneous adsorption process of sulfate, which is done mostly for adsorbents that remove sulfate through hydrogen and covalent bonding. The kinetic studies illustrated that both film diffusion and pore-diffusion could control sulfate uptake by the various adsorbents. The thermodynamic studies showed that the sulfate adsorption is endothermic and spontaneous except for the sulfate removal by polypyrrole-modified activated-carbons and LDH-HPI mine waste, which requires energy for adsorption.
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Affiliation(s)
- Bahareh Sadeghalvad
- Department of Civil, Environmental, and Construction Engineering, Texas Tech University, 2500 Broadway, Lubbock, TX, 79409, USA.
| | - Niyayesh Khorshidi
- Department of Mining & Metallurgical Engineering, Amirkabir University of Technology, Tehran, 424 Hafez Avenue, Tehran, Iran.
| | - Amirreza Azadmehr
- Department of Mining & Metallurgical Engineering, Amirkabir University of Technology, Tehran, 424 Hafez Avenue, 1875-4413, Tehran, Iran.
| | - Mika Sillanpää
- Institute of Research and Development, Duy Tan University, Da Nang, 550000, Viet Nam; Faculty of Environment and Chemical Engineering, Duy Tan University, Da Nang, 550000, Viet Nam; School of Civil Engineering and Surveying, Faculty of Health, Engineering and Sciences, University of Southern Queensland, West Street, Toowoomba, 4350, QLD, Australia; Department of Chemical Engineering, School of Mining, Metallurgy and Chemical Engineering, University of Johannesburg, P. O. Box 17011, Doornfontein, 2028, South Africa.
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Sadeghalvad B, Azadmehr A, Hezarkhani A. A new approach to improve sulfate uptake from contaminated aqueous solution: Metal layered double hydroxides functionalized metasomatic rock. SEP SCI TECHNOL 2018. [DOI: 10.1080/01496395.2018.1518334] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Bahareh Sadeghalvad
- Department of Mining & Metallurgical Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Amirreza Azadmehr
- Department of Mining & Metallurgical Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Ardeshir Hezarkhani
- Department of Mining & Metallurgical Engineering, Amirkabir University of Technology, Tehran, Iran
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Horányi G, Kálmán E. Anion specific adsorption on Fe2O3 and AlOOH nanoparticles in aqueous solutions: comparison with hematite and γ-Al2O3. J Colloid Interface Sci 2004; 269:315-9. [PMID: 14654390 DOI: 10.1016/s0021-9797(03)00750-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The specific adsorption of radiolabeled sulfate and phosphate ions from perchlorate supporting electrolyte onto nano-AlOOH and nano-Fe(2)O(3) powder has been investigated. The pH dependence of the adsorption of anions onto nanopowders was compared with that of the same ions onto gamma-Al(2)O(3) and hematite. It was demonstrated that the character of the pH dependence of the adsorption is very similar in the comparable cases. It was found, however, that in contrast to the behavior of gamma-Al(2)O(3), nano-AlOOH dissolves at a significant rate at low pH values (pH<2). Thus the study of the pH dependence of the anion adsorption encounters difficulties at these pH values. Disregarding this fact, it can be concluded that no special effects can be observed in the anion adsorption onto the nano-oxides studied.
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Affiliation(s)
- G Horányi
- Research Laboratory of Materials and Environmental Chemistry, Chemical Research Center, Hungarian Academy of Sciences, 1525, PO Box 17, Budapest, Hungary.
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