| 1. |
- A. da Cruz, Márcia G., et al.
(author)
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Solvent-free synthesis of photoluminescent carbon nanoparticles from lignin-derived monomers as feedstock
- 2023
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In: Green Chemistry Letters and Reviews. - 1751-8253 .- 1751-7192. ; 16:1
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Journal article (peer-reviewed)abstract
- Photoluminescent carbon nanoparticles (CNPs), such as carbon dots (CDs), have attracted much attention owing to a unique set of properties, like high and tunable fluorescence. In this way, the use of carbon-rich lignin has been demonstrated to be a sustainable approach to producing a broad range of photoluminescent CNPs. However, the valorization of this complex polyphenol is limited when it comes to green and efficient ways of conversion. In addition, the existing solvothermal approaches using lignin often result in CDs with low photoluminescence, while flammable and/or toxic solvents are employed. Here, we depolymerized technical lignins, i.e. kraft and soda, through electroreductive cleavage in two different sustainable media: deep eutectic solvent and levulinic acid. After depolymerization, lignin-derived monomers were generated, with a predominance of aryl ether and phenolic groups, which were further combined with 1,2-Phenylenediamine to produce N-doped CNPs in a solvent-free approach. Photoluminescent CNPs with varied sizes were generated (5–50 nm), which presented a wide photoluminescence emission, from blue to red, depending on solvent polarity. These results demonstrate a feasible and sustainable route for the solvent-free synthesis of photoluminescent CNPs using lignin-derived monomers as carbon source, which may find applications in a wide range of fields.
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| 2. |
- Budnyak, Tetyana, et al.
(author)
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LignoPhot : Conversion of hydrolysis lignin into the photoactive hybrid lignin/Bi4O5Br2/BiOBr composite for simultaneous dyes oxidation and Co2+ and Ni2+ recycling
- 2021
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In: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 279
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Journal article (peer-reviewed)abstract
- Valorization of lignin is still an open question and lignin has therefore remained an underutilized biomaterial. This situation is even more pronounced for hydrolysis lignin, which is characterized by a highly condensed and excessively cross-linked structure. We demonstrate the synthesis of photoactive lignin/Bi4O5Br2/BiOBr bio-inorganic composites consisting of a lignin substrate that is coated by semiconducting nanosheets. The XPS analysis reveals that growing these nanosheets on lignin instead on cellulose prevents the formation of Bi5+ ions at the surface region, yielding thus a modified hetero-junction Bi4O5Br2/BiOBr. The material contains 18.9% of Bi4O5Br2/BiOBr and is effective for the photocatalytic degradation of cationic methylene blue (MB) and zwitterionic rhodamine B (RhB) dyes under light irradiation. Lignin/Bi4O5Br2/BiOBr decreases the dye concentration from 80 mg L-1 to 12.3 mg L-1 for RhB (85%) and from 80 mg L-1 to 4.4 mg L-1 for MB (95%). Complementary to the dye degradation, the lignin as a main component of the composite, was found to be efficient and rapid biosorbent for nickel, lead, and cobalt ions. The low cost, stability and ability to simultaneously photo-oxidize organic dyes and adsorb metal ions, make the photoactive lignin/Bi4O5Br2/BiOBr composite a prospective material for textile wastewaters remediation and metal ions recycling.
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| 3. |
- Onwumere, Joy, et al.
(author)
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A Multivariant Metal-Organic Framework and Bismuth Compound Based Composite as An Efficient Photocatalyst
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Other publication (other academic/artistic)abstract
- Water pollution treatment requires maintaining clean and safe water resources. Dyes, which are frequently linked to textile industries, pollute water and cause serious environmental. Problems. To address this issue, we prepare a novel composite combining photoactive metal-organic framework (MOF) and Bismuth oxybromide (BiOBr). MIL-100(Ti, Co)/BiOBr and MIL-100(Ti, Ni)/BiOBr composites were fabricated by a one-pot solvothermal method. MIL-100(Ti, Co)/BiOBr and MIL-100(Ti, Ni)/BiOBr composites show the highest photocatalytic activity in the degradation of Rhodamine B, which is more than 60% higher than pure its individual counterpart in the first 20 minutes. This is a result of the heterojunction formed by both the MOF and BiOBr. In these visible-light heterojunction photocatalysts, the MOF increased the specific surface area of the semiconductor, leading to an improved photocatalytic performance.
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| 4. |
- Onwumere, Joy
(author)
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A Multivariant Metal-Organic Framework and Bismuth Compound Based Composite as An Efficient Photocatalyst
-
Other publication (other academic/artistic)abstract
- Water pollution treatment requires maintaining clean and safe water resources. Dyes, which are frequently linked to textile industries, pollute water and cause serious environmental. problems. To address this issue, we prepare a novel composite combining photoactive metal-organic framework (MOF) and Bismuth oxybromide (BiOBr). MIL-100(Ti, Co)/BiOBr and MIL-100(Ti, Ni)/BiOBr composites were fabricated by a one-pot solvothermal method. MIL-100(Ti, Co)/BiOBr and MIL-100(Ti, Ni)/BiOBr composites show the highest photocatalytic activity in the degradation of Rhodamine B, which is more than 60% higher than pure its individual counterpart in the first 20 minutes. This is a result of the heterojunction formed by both the MOF and BiOBr. In these visible-light heterojunction photocatalysts, the MOF increased the specific surface area of the semiconductor, leading to an improved photocatalytic performance.
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| 5. |
- Onwumere, Joy, et al.
(author)
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Bismuth Oxybromide Nanosheet as an Efficient Photocatalyst for Dye Degradation
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Other publication (other academic/artistic)abstract
- The contamination of water resources by organic pollutants presents significant environmental and health challenges. Therefore, it is urgent to develop highly efficient and green approach for treating organic water pollutants. Bismuth oxybromide (BiOBr) has gained attention due to its high photoactivity. In this work, we report a modification to improve its photocatalytic activity. BiOBr were prepared using a capping agent, benzene-1,3,5-tricarboxylic acid, to tune the morphology of the compound. The resulting BiOBr shows nanosheet morphology, which provides a high surface-to-volume ratio and a wider bandgap compared to bulk BiOBr. As a result, the photocatalytic performance of BiOBr is improved. By comparing to benchmark TiO2 and bulk BiOBr catalysts, the BiOBr nanosheets show the best performance for photodegradation of Rhodamine B.
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| 6. |
- Onwumere, Joy, et al.
(author)
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CelluPhot : Hybrid Cellulose-Bismuth Oxybromide Membrane for Pollutant Removal
- 2020
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In: ACS Applied Materials and Interfaces. - : NLM (Medline). - 1944-8244 .- 1944-8252. ; 12:38, s. 42891-42901
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Journal article (peer-reviewed)abstract
- The simultaneous removal of organic and inorganic pollutants from wastewater is a complex challenge and requires usually several sequential processes. Here, we demonstrate the fabrication of a hybrid material that can fulfill both tasks: (i) the adsorption of metal ions due to the negative surface charge, and (ii) photocatalytic decomposition of organic compounds. The bioinorganic hybrid membrane consists of cellulose fibers to ensure mechanical stability and of Bi4O5Br2/BiOBr nanosheets. The composite is synthesized at low temperature of 115 °C directly on the cellulose membrane (CM) in order to maintain the carboxylic and hydroxyl groups on the surface that are responsible for the adsorption of metal ions. The composite can adsorb both Co(II) and Ni(II) ions and the kinetic study confirmed a good agreement of experimental data with the pseudo-second-order equation kinetic model. CM/Bi4O5Br2/BiOBr showed higher affinity to Co(II) ions than to Ni(II) ions from diluted aqueous solutions. The bioinorganic composite demonstrates a synergistic effect in the photocatalytic degradation of rhodamine B (RhB) by exceeding the removal efficiency of single components. The fabrication of the biologic-inorganic interface was confirmed by various analytical techniques including scanning electron microscopy (SEM), scanning transmission electron microscopy with energy dispersive X-ray spectroscopy (STEM EDX) mapping, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The presented approach for controlled formation of the bioinorganic interface between natural material (cellulose) and nanoscopic inorganic materials of tailored morphology (Bi-O-Br system) enables the significant enhancement of materials functionality.
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