Brown seaweeds are interesting materials to be used as biosorbents for heavy metals due to their high binding ability and low cost. The study of the passive biosorption of protons on this kind of materials and its dependency on pH, ionic strength, and medium composition is essential for the practical application of brown algae in wastewater treatment. This work reports the results of the study of the proton binding equilibria of dead biomass from the seaweeds Sargassum muticum, Cystoseira baccata, and Saccorhiza polyschides by potentiometric titration with a glass electrode in the pH range between 2 and 8. Two different salts, NaCl and KNO3, in concentrations ranging from 0.05 to 2 mol x L(-1), were used as background electrolytes. The influence of the ionic strength was accounted for by means of the Donnan model in combination with the master curve approach. Different empirical expressions to describe the swelling behavior of the biosorbent were tested. On the basis of the intrinsic affinity distribution analysis a unimodal Langmuir-Freundlich isotherm was selected to describe the proton binding properties. The results show very little influence of the type of salt. The ionic strength dependency of the proton binding is very similar for the three species, and average empirical expressions of the Donnan volume are proposed. The maximum proton binding capacities obtained ranged between 2.4 and 2.9 mol x kg(-1), with average intrinsic proton affinity constants between 3.1 and 3.3, and heterogeneity parameters of ca. 0.5 for S. muticum and C. baccata, and slightly higher (ca. 0.7) for S. polyschides. The combined Langmuir-Freundlich equation and Donnan model allowed a good description of the experimental charge vs pH curves obtained.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/es0343353 | DOI Listing |
BMC Chem
January 2025
Energy Systems Engineering Department, Engineering Faculty, Adana Alparslan Türkeş Science and Technology University, 01250, Adana, Türkiye.
Although the antiallergic properties of compounds such as CAPE, Melatonin, Curcumin, and Vitamin C have been poorly discussed by experimental studies, the antiallergic properties of these famous molecules have never been discussed with calculations. The histamine-1 receptor (H1R) belongs to the family of rhodopsin-like G-protein-coupled receptors expressed in cells that mediate allergies and other pathophysiological diseases. In this study, pharmacological activities of FDA-approved second generation H1 antihistamines (Levocetirizine, desloratadine and fexofenadine) and molecules such as CAPE, Melatonin, Curcumin, Vitamin C, ADMET (Absorption, Distribution, Metabolism, Excretion, Toxicity) profiles, density functional theory (DFT), molecular docking, biological targets and activities were compared by calculating.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
December 2024
School of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Chemical Reaction Engineering, Laboratory of New Energy & New Function Materials, Yanan University, Yan'an 716000, China.
Elemental analysis, infrared spectroscopy, and X-ray single crystal diffraction indicated that a novel metal-organic framework (Tb-MOF) designated as 0.5n[Hbpy]·[Tb(dpa)(HO)]·4nHO was synthesized successfully, (where Hdpa = 5-(3, 4-dicarboxy- phenoxy) isophenic acid, bpy = protonated 4,4'-bipyridine). Tb-MOF adopts a 3D network structure based on Tb ions and the (dpa) ligand through µ: η, η, η, η binding modes.
View Article and Find Full Text PDFWater Res
December 2024
Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China. Electronic address:
Activation of HO cleavage for H* production by defect engineering eliminates the insufficient supply of protons in the NORR process under neutral conditions. However, it remains challenging to precisely control the defect formation for optimizing the equilibrium between H* production and H* binding. Here, we propose a strategy to boost defect generation through S-doping induced NiFe-LDH lattice distortion, and successfully optimize the balance of H* production and binding.
View Article and Find Full Text PDFNat Commun
January 2025
Shanghai Fifth People's Hospital, Fudan University, and Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
Vesicular monoamine transporter 2 (VMAT2) is crucial for packaging monoamine neurotransmitters into synaptic vesicles, with their dysregulation linked to schizophrenia, mood disorders, and Parkinson's disease. Tetrabenazine (TBZ) and valbenazine (VBZ), both FDA-approved VMAT2 inhibitors, are employed to treat chorea and tardive dyskinesia (TD). Our study presents the structures of VMAT2 bound to substrates serotonin (5-HT) and dopamine (DA), as well as the inhibitors TBZ and VBZ.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Inorganic Spectroscopy, Max Planck Institute for Chemical Energy Conversion, Mülheim an der Ruhr, Germany, 45470.
Molybdenum nitrogenase plays a crucial role in the biological nitrogen cycle by catalyzing the reduction of dinitrogen (N) to ammonia (NH) under ambient conditions. However, the underlying mechanisms of nitrogenase catalysis, including electron and proton transfer dynamics, remain only partially understood. In this study, we covalently attached molybdenum nitrogenase (MoFe) to gold electrodes and utilized surface-enhanced infrared absorption spectroscopy (SEIRA) coupled with electrochemistry techniques to investigate its catalytic mechanism.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!