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Claesson PM, Wojas NA, Corkery R, Dedinaite A, Schoelkopf J, Tyrode E. The dynamic nature of natural and fatty acid modified calcite surfaces. Phys Chem Chem Phys 2024; 26:2780-2805. [PMID: 38193529 DOI: 10.1039/d3cp04432g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
Calcium carbonate, particularly in the form of calcite, is an abundant mineral widely used in both human-made products and biological systems. The calcite surface possesses a high surface energy, making it susceptible to the adsorption of organic contaminants. Moreover, the surface is also reactive towards a range of chemicals, including water. Consequently, studying and maintaining a clean and stable calcite surface is only possible under ultrahigh vacuum conditions and for limited amounts of time. When exposed to air or solution, the calcite surface undergoes rapid transformations, demanding a comprehensive understanding of the properties of calcite surfaces in different environments. Similarly, attention must also be directed towards the kinetics of changes, whether induced by fluctuating environments or at constant condition. All these aspects are encompassed in the expression "dynamic nature", and are of crucial importance in the context of the diverse applications of calcite. In many instances, the calcite surface is modified by adsorption of fatty acids to impart a desired nonpolar character. Although the binding between carboxylic acid groups and calcite surfaces is strong, the fatty acid layer used for surface modification undergoes significant alterations when exposed to water vapour and liquid water droplets. Therefore, it is also crucial to understand the dynamic nature of the adsorbed layer. This review article provides a comprehensive overview of the current understanding of both the dynamics of the calcite surface as well as when modified by fatty acid surface treatments.
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Affiliation(s)
- Per M Claesson
- KTH Royal Institute of Technology, Department of Chemistry, Division of Surface and Corrosion Science, Teknikringen 29, SE-100 44 Stockholm, Sweden.
| | - Natalia A Wojas
- RISE Research Institutes of Sweden, Division of Bioeconomy and Health - Material and Surface Design, Drottning Kristinas väg 61B, SE-114 28 Stockholm, Sweden
| | - Robert Corkery
- KTH Royal Institute of Technology, Department of Chemistry, Division of Surface and Corrosion Science, Teknikringen 29, SE-100 44 Stockholm, Sweden.
| | - Andra Dedinaite
- KTH Royal Institute of Technology, School of Engineering Sciences in Chemistry, Biotechnology and Health, Engineering Pedagogics, SE-100 44 Stockholm, Sweden
- RISE Research Institutes of Sweden, Division Bioeconomy and Health, Department Chemical Process and Pharmaceutical Development, Box 5604, SE-114 86 Stockholm, Sweden
| | | | - Eric Tyrode
- KTH Royal Institute of Technology, Department of Chemistry, Division of Surface and Corrosion Science, Teknikringen 29, SE-100 44 Stockholm, Sweden.
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Wojas NA, Tyrode E, Corkery R, Ernstsson M, Wallqvist V, Järn M, Swerin A, Schoelkopf J, Gane PAC, Claesson PM. Calcite Surfaces Modified with Carboxylic Acids (C 2 to C 18): Layer Organization, Wettability, Stability, and Molecular Structural Properties. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:14840-14852. [PMID: 37824837 PMCID: PMC10601537 DOI: 10.1021/acs.langmuir.3c01252] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 08/18/2023] [Indexed: 10/14/2023]
Abstract
A fundamental understanding of the interactions between mineral surfaces and amphiphilic surface modification agents is needed for better control over the production and uses of mineral fillers. Here, we controlled the carboxylic acid layer formation conditions on calcite surfaces with high precision via vapor deposition. The properties of the resulting carboxylic acid layers were analyzed using surface-sensitive techniques, such as atomic force microscopy (AFM), contact angle measurements, angle resolved X-ray photoelectron spectroscopy (XPS), and vibrational sum-frequency spectroscopy. A low wettability was achieved with long hydrocarbon chain carboxylic acids such as stearic acid. The stearic acid layer formed by vapor deposition is initially patchy, but with increasing vapor exposure time, the patches grow and condense into a homogeneous layer with a thickness close to that expected for a monolayer as evaluated by AFM and XPS. The build-up process of the layer occurs more rapidly at higher temperatures due to the higher vapor pressure. The stability of the deposited fatty acid layer in the presence of a water droplet increases with the chain length and packing density in the adsorbed layer. Vibrational sum frequency spectroscopy data demonstrate that the stearic acid monolayers on calcite have their alkyl chains in an all-trans conformation and are anisotropically distributed on the plane of the surface, forming epitaxial monolayers. Vibrational spectra also show that the stearic acid molecules interact with the calcite surface through the carboxylic acid headgroup in both its protonated and deprotonated forms. The results presented provide new molecular insights into the properties of adsorbed carboxylic acid layers on calcite.
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Affiliation(s)
- Natalia A. Wojas
- RISE
Research Institutes of Sweden, Division
of Bioeconomy and Health–Material and Surface Design, Box 5607, SE-114 86 Stockholm, Sweden
- KTH
Royal Institute of Technology, Department
of Chemistry, Teknikringen 30 SE, 11428 Stockholm, Sweden
| | - Eric Tyrode
- KTH
Royal Institute of Technology, Department
of Chemistry, Teknikringen 30 SE, 11428 Stockholm, Sweden
| | - Robert Corkery
- KTH
Royal Institute of Technology, Department
of Chemistry, Teknikringen 30 SE, 11428 Stockholm, Sweden
- Australian
National University Department of Applied Mathematics, Research School of Physics and Engineering, Canberra ACT 0200, Australia
| | - Marie Ernstsson
- RISE
Research Institutes of Sweden, Division
of Bioeconomy and Health–Material and Surface Design, Box 5607, SE-114 86 Stockholm, Sweden
| | - Viveca Wallqvist
- RISE
Research Institutes of Sweden, Division
of Bioeconomy and Health–Material and Surface Design, Box 5607, SE-114 86 Stockholm, Sweden
| | - Mikael Järn
- RISE
Research Institutes of Sweden, Division
of Bioeconomy and Health–Material and Surface Design, Box 5607, SE-114 86 Stockholm, Sweden
| | - Agne Swerin
- Karlstad
University Faculty of Health Science and Technology, Department of Engineering and Chemical Sciences: Chemical Engineering, SE-651 88 Karlstad, Sweden
| | | | - Patrick A. C. Gane
- Aalto University
School of Chemical Engineering, Department
of Bioproducts and Biosystems, P.O. Box
16300, FI-00076 Aalto, Finland
- University
of Belgrade, Faculty of Technology and Metallurgy, Karnegijeva 4, 11200 Belgrade, Serbia
| | - Per M. Claesson
- KTH
Royal Institute of Technology, Department
of Chemistry, Teknikringen 30 SE, 11428 Stockholm, Sweden
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"Green" nZVI-Biochar as Fenton Catalyst: Perspective of Closing-the-Loop in Wastewater Treatment. Molecules 2023; 28:molecules28031425. [PMID: 36771092 PMCID: PMC9921900 DOI: 10.3390/molecules28031425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/09/2023] [Accepted: 01/11/2023] [Indexed: 02/05/2023] Open
Abstract
In the framework of wastewater treatment plants, sewage sludge can be directed to biochar production, which when coupled with an external iron source has the potential to be used as a carbon-iron composite material for treating various organic pollutants in advanced oxidation processes. In this research, "green" synthesized nano zero-valent iron (nZVI) supported on sewage sludge-based biochar (BC)-nZVI-BC was used in the Fenton process for the degradation of the recalcitrant organic molecule. In this way, the circular economy principles were supported within wastewater treatment with immediate loop closing; unlike previous papers, where only the water treatment was assessed, the authors proposed a new approach to wastewater treatment, combining solutions for both water and sludge. The following phases were implemented: synthesis and characterization of nano zero-valent iron supported on sewage sludge-based biochar (nZVI-BC); optimization of organic pollutant removal (Reactive Blue 4 as the model pollutant) by nZVI-BC in the Fenton process, using a Definitive Screening Design (DSD) model; reuse of the obtained Fenton sludge, as an additional catalytic material, under previously optimized conditions; and assessment of the exhausted Fenton sludge's ability to be used as a source of nutrients. nZVI-BC was used in the Fenton treatment for the degradation of Reactive Blue 4-a model substance containing a complex and stable anthraquinone structure. The DSD model proposes a high dye-removal efficiency of 95.02% under the following optimal conditions: [RB4] = 50 mg/L, [nZVI] = 200 mg/L, [H2O2] = 10 mM. pH correction was not performed (pH = 3.2). Afterwards, the remaining Fenton sludge, which was thermally treated (named FStreated), was applied as a heterogeneous catalyst under the same optimal conditions with a near-complete organic molecule degradation (99.56% ± 0.15). It could be clearly noticed that the cumulative amount of released nutrients significantly increased with the number of leaching experiments. The highest cumulative amounts of released K, Ca, Mg, Na, and P were therefore observed at the fifth leaching cycle (6.40, 1.66, 1.12, 0.62, 0.48 and 58.2 mg/g, respectively). According to the nutrient release and toxic metal content, FStreated proved to be viable for agricultural applications; these findings illustrated that the "green" synthesis of nZVI-BC not only provides innovative and efficient Fenton catalysts, but also constitutes a novel approach for the utilization of sewage sludge, supporting overall process sustainability.
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