Reactions

21 pages, 2023 KB

Open AccessArticle

Efficient Decolourisation of Astrazon Pink Dye Using Biocarbon Derived from Prosopis juliflora Shells: Kinetics, Isotherms, and RSM-Based Optimization for Sustainable Wastewater Treatment

by Lakshmi Mohanraj and Ranjitha Jambulingam

Reactions 2025, 6(4), 57; https://doi.org/10.3390/reactions6040057 - 17 Oct 2025

Abstract

This study investigates the efficiency of biocarbon derived from Prosopis juliflora shells in removing Astrazon pink dye from aqueous solutions. The biocarbon obtained from the thermochemical process was characterised using FTIR Spectroscopy, SEM microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS), and XRD. Batch adsorption [...] Read more.

This study investigates the efficiency of biocarbon derived from Prosopis juliflora shells in removing Astrazon pink dye from aqueous solutions. The biocarbon obtained from the thermochemical process was characterised using FTIR Spectroscopy, SEM microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS), and XRD. Batch adsorption experiments were conducted to assess various factors, including the Potential of Hydrogen (pH), Dosage of biocarbon, Astrazon pink dye concentration, temperature, and Time of contact. Similarly, Adsorption isotherm models, including the Langmuir and the Freundlich isotherms, were used to evaluate the adsorption capacity. In contrast, pseudo-first-order and pseudo-second-order models were used to analyse the kinetics of dye adsorption. The interactive effects of selected variables on the removal of Astrazon Pink dye from synthetic water were determined using Response Surface Methodology (RSM). The maximum dye uptake, 98.54%, was achieved with a biochar dose of 8 g/L at 50 ppm dye concentration, pH 7.5, and 35 °C. The Freundlich adsorption isotherm model and the pseudo-second-order kinetic model are the better-fitting models for the dye adsorption process, with R² values of 0.99. Consequently, the thermodynamic parameters indicate that the process is endothermic and spontaneous. Full article

12 pages, 2898 KB

Open AccessArticle

Unraveling the Electrochemical Reaction Mechanism of Bronze-Phase Titanium Dioxide in Sodium-Ion Batteries

by Denis Opra, Sergey Sinebryukhov, Alexander Sokolov, Andrey Gerasimenko, Sviatoslav Sukhoverkhov, Andrey Sidorin, Alexandra Zavidnaya and Sergey Gnedenkov

Reactions 2025, 6(4), 56; https://doi.org/10.3390/reactions6040056 - 7 Oct 2025

Viewed by 323

Abstract

Searching anode materials is an important task for the development of sodium-ion batteries. In this regard, bronze-phase titanium dioxide, TiO₂(B), has been considered as one of the promising materials, owing to its crystal structure with open channels and voids facilitating Na [...] Read more.

Searching anode materials is an important task for the development of sodium-ion batteries. In this regard, bronze-phase titanium dioxide, TiO₂(B), has been considered as one of the promising materials, owing to its crystal structure with open channels and voids facilitating Na⁺ diffusion and storage. However, the electrochemical de-/sodiation mechanism of TiO₂(B) has not been clearly comprehended, and further experiments are required. Herein, in situ and ex situ observations by a combination of X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, gas chromatography–mass spectrometry was used to provide additional insights into the electrochemical reaction scenario of bronze-phase TiO₂ in Na-ion batteries. The findings reveal that de-/sodiation of TiO₂(B) occurs through a reversible intercalation reaction and without the involvement of the conversion reaction (no metallic titanium is formed and no oxygen is released). At the same time, upon the first Na⁺ uptake process, crystalline TiO₂(B) becomes partially amorphous, but is still driven by the Ti⁴⁺/Ti³⁺ redox couple. Importantly, TiO₂(B) has pseudocapacitive electrochemical behavior during de-/sodiation based on a quantitative analysis of the cyclic voltammetry data. The results obtained in this study complement existing insights into the sodium storage mechanisms of TiO₂(B) and provide useful knowledge for further improving its anode performance for SIBs application. Full article

► Show Figures

Figure 1

41 pages, 6916 KB

Open AccessReview

Green Photocatalysis: A Comprehensive Review of Plant-Based Materials for Sustainable Water Purification

by Safiya Mallah, Mariam El Mchaouri, Salma El Meziani, Hafida Agnaou, Hajar El Haddaj, Wafaa Boumya, Noureddine Barka and Alaâeddine Elhalil

Reactions 2025, 6(4), 55; https://doi.org/10.3390/reactions6040055 - 5 Oct 2025

Viewed by 541

Abstract

Green synthesis represents a sustainable, reliable, and eco-friendly approach for producing various materials and nanomaterials, including metal and metal oxide nanoparticles. This environmentally conscious method has garnered significant attention from materials scientists. In recent years, interest in plant-mediated nanoparticle synthesis has grown markedly, [...] Read more.

Green synthesis represents a sustainable, reliable, and eco-friendly approach for producing various materials and nanomaterials, including metal and metal oxide nanoparticles. This environmentally conscious method has garnered significant attention from materials scientists. In recent years, interest in plant-mediated nanoparticle synthesis has grown markedly, owing to advantages such as enhanced product stability, low synthesis costs, and the use of non-toxic, renewable resources. This review specifically focuses on the green synthesis of metal oxide nanoparticles using plant extracts, highlighting five key oxides: TiO₂, ZnO, WO₃, CuO, and Fe₂O₃, which are prepared through various plant-based methods. The release of toxic effluents like synthetic dyes into the environment poses serious threats to aquatic ecosystems and human health. Therefore, the application of biosynthesized nanoparticles in removing such pollutants from industrial wastewater is critically examined. This paper discusses the synthesis routes, characterization techniques, green synthesis methodologies, and evaluates the photocatalytic performance and dye degradation mechanisms of these plant-derived nanoparticles. Full article

► Show Figures

Figure 1

16 pages, 627 KB

Open AccessArticle

Regioselectivity of the Claisen Rearrangement of Meta- and Para-Substituted Allyl Aryl Ethers

by William Thomas Möller, Svava Dögg Hreinsdóttir, Luis Antonio Arana and Benjamín Ragnar Sveinbjörnsson

Reactions 2025, 6(4), 54; https://doi.org/10.3390/reactions6040054 - 5 Oct 2025

Viewed by 747

Abstract

The regioselectivity of the Claisen rearrangement with different meta-substituted and meta- and para-substituted allyl phenyl ethers was investigated. The main results were that in meta-substituted Claisen rearrangements the regioselectivity depends roughly on the electronic nature of the substituent, with electron-donating groups favoring migration [...] Read more.

The regioselectivity of the Claisen rearrangement with different meta-substituted and meta- and para-substituted allyl phenyl ethers was investigated. The main results were that in meta-substituted Claisen rearrangements the regioselectivity depends roughly on the electronic nature of the substituent, with electron-donating groups favoring migration further from the meta-substituent while electron-withdrawing groups favor migration towards the meta-substituent. Different para-substituents were tested with two meta-substituents, Me, and Cl. Most of the para-substituent tested had a clear effect on the product ratio, in all but one case enhancing the proportion of the major product favored by the meta-substituent. Population analysis was performed with Mulliken, Löwdin, Hirshfeld, and natural population analysis to analyze the influence of the substituents on the atomic charges on the reaction sites. It was observed that the atomic charge on the carbon that forms the major isomer is of higher negativity than the atomic charge on the carbon that forms the minor isomer. Full article

► Show Figures

Figure 1

16 pages, 1415 KB

Open AccessArticle

Decolorization and Detoxification of Synthetic Dyes by Trametes versicolor Laccase Under Salt Stress Conditions

by Thaís Marques Uber, Danielly Maria Paixão Novi, Luana Yumi Murase, Vinícius Mateus Salvatori Cheute, Samanta Shiraishi Kagueyama, Alex Graça Contato, Rosely Aparecida Peralta, Adelar Bracht and Rosane Marina Peralta

Reactions 2025, 6(4), 53; https://doi.org/10.3390/reactions6040053 - 3 Oct 2025

Viewed by 370

Abstract

Fungal laccases are promising oxidative enzymes for bioremediation applications, particularly in the degradation of synthetic dyes present in industrial effluents. Here, we evaluated the inhibitory effects of sodium chloride (NaCl) and sodium sulfate (Na₂SO₄) on the activity of Trametes [...] Read more.

Fungal laccases are promising oxidative enzymes for bioremediation applications, particularly in the degradation of synthetic dyes present in industrial effluents. Here, we evaluated the inhibitory effects of sodium chloride (NaCl) and sodium sulfate (Na₂SO₄) on the activity of Trametes versicolor laccase and its ability to decolorize Congo Red (CR), Malachite Green (MG), and Remazol Brilliant Blue R (RBBR). Enzyme assays revealed concentration-dependent inhibition, with IC₅₀ values of 0.22 ± 0.04 M for NaCl and 1.00 ± 0.09 M for Na₂SO₄, indicating stronger inhibition by chloride. Kinetic modeling showed mixed-type inhibition for both salts. Despite this effect, the enzyme maintained significant activity: after 12 h, decolorization efficiencies reached 95 ± 4.0% for MG, 88 ± 3.0% for RBBR, and 75 ± 3.0% for CR, even in the presence of 0.5 M salts. When applied to a mixture of the three dyes, decolorization decreased only slightly in saline medium (94.04 ± 4.0% to 83.43 ± 5.1%). FTIR spectra revealed minor structural changes, but toxicity assays confirmed marked detoxification, with radicle length in lettuce seeds increasing from 20–38 mm (untreated dyes) to 41–48 mm after enzymatic treatment. Fungal growth assays corroborated reduced toxicity of treated dyes. These findings demonstrate that T. versicolor laccase retains functional robustness under ionic stress, supporting its potential application in saline textile wastewater remediation. Full article

(This article belongs to the Topic Green and Sustainable Catalytic Process)

► Show Figures

Graphical abstract

10 pages, 1449 KB

Open AccessArticle

Enhanced Cycling Stability of High-Voltage Sodium-Ion Batteries via DFEC-Driven Fluorinated Interface Engineering

by Xin Li, Yali Yao and Xinying Liu

Reactions 2025, 6(4), 52; https://doi.org/10.3390/reactions6040052 - 1 Oct 2025

Viewed by 782

Abstract

With their considerable capacity and structurally favorable characteristics, layered transition metal oxides have become strong contenders for cathode use in sodium-ion batteries (SIBs). Nevertheless, their practical deployment is challenged by pronounced capacity loss, predominantly induced by unstable cathode–electrolyte interphase (CEI) at elevated voltages. [...] Read more.

With their considerable capacity and structurally favorable characteristics, layered transition metal oxides have become strong contenders for cathode use in sodium-ion batteries (SIBs). Nevertheless, their practical deployment is challenged by pronounced capacity loss, predominantly induced by unstable cathode–electrolyte interphase (CEI) at elevated voltages. In this study, difluoroethylene carbonate (DFEC) is introduced as a functional electrolyte additive to engineer a robust and uniform CEI. The fluorine-enriched CEI effectively suppresses parasitic reactions, mitigates continuous electrolyte decomposition, and facilitates stable Na⁺ transport. Consequently, Na/NaNi_1/3Fe_1/3Mn_1/3O₂ (Na/NFM) cells with 2 wt.% DFEC retain 78.36% of their initial capacity after 200 cycles at 1 C and 4.2 V, demonstrating excellent long-term stability. Density functional theory (DFT) calculations confirm the higher oxidative stability of DFEC compared to conventional solvents, further supporting its interfacial protection role. This work offers valuable insights into electrolyte additive design for high-voltage SIBs and provides a practical route to significantly improve long-term electrochemical performance. Full article

(This article belongs to the Special Issue Feature Papers in Reactions in 2025)

► Show Figures

Figure 1

20 pages, 4097 KB

Open AccessArticle

Ethylene and 1-butene Oligomerization with Benzimidazole Complexes of Nickel and Iron: A Case of Tandem Reaction

by Nelson N. dos Santos, Marcos F. Silva, Alexandre F. Young, Marcos L. Dias and Mariana M. V. M. Souza

Reactions 2025, 6(4), 51; https://doi.org/10.3390/reactions6040051 - 24 Sep 2025

Viewed by 374

Abstract

The coordination chemistry of benzimidazole ligands combines σ donation and π backbonding. Owing to this electronic flexibility, benzimidazole ligands stabilize both electron deficient and electron-rich transition states in the catalytic cycle of Ziegler-Natta polymerizations. In this study, Fe(III) and Ni(II) complexes of 2-substituted-benzimidazoles [...] Read more.

The coordination chemistry of benzimidazole ligands combines σ donation and π backbonding. Owing to this electronic flexibility, benzimidazole ligands stabilize both electron deficient and electron-rich transition states in the catalytic cycle of Ziegler-Natta polymerizations. In this study, Fe(III) and Ni(II) complexes of 2-substituted-benzimidazoles were tested as catalysts for ethylene and 1-butene oligomerization. The tests realized in toluene yielded mainly butenes and minor amounts of hexenes. When dichloromethane was used as solvent, a tandem reaction took place and 1-butene produced by ethylene dimerization was further oligomerized, yielding octenes and dodecenes as main products. All tested catalysts exhibited moderate selectivity for 1-octene, indicating 1-ω enchainment in 1-butene dimerization. Beyond catalytic tests, a theoretical study of the ligand 2,2′-(furan-2,5-diyl)bis(1H-benzimidazole) confirmed the planar structure of this compound as evidenced by NMR spectroscopy. Full article

► Show Figures

Figure 1

Journal Menu

Journal Browser

Reactions, Volume 6, Issue 4 (December 2025) – 7 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI