Removal of phosphorus by modified bentonite:polyvinylidene fluoride membrane-study of adsorption performance and mechanism.

Enhanced phosphorus management, geared towards sustainability, is imperative due to its indispensability for all life forms and its close association with water bodies' eutrophication, primarily stemming from anthropogenic activities. In response to this concern, innovative technologies rooted in the circular economy are emerging, to remove and recover this vital nutrient to global food production. This research undertakes an evaluation of the dead-end filtration performance of a mixed matrix membrane composed of modified bentonite (MB) and polyvinylidene fluoride (PVDF) for efficient phosphorus removal from water media. The MB:PVDF membrane exhibited higher permeability and surface roughness compared to the pristine membrane, showcasing an adsorption capacity (Q) of 23.2 mgP·m-2. Increasing the adsorbent concentration resulted in a higher removal capacity (from 16.9 to 23.2 mgP·m-2) and increased solution flux (from 0.5 to 16.5 L·m-2·h-1) through the membrane. The initial phosphorus concentration demonstrates a positive correlation with the adsorption capacity of the material, while the system pressure positively influences the observed flux. Conversely, the presence of humic acid exerts an adverse impact on both factors. Additionally, the primary mechanism involved in the adsorption process is identified as the formation of inner-sphere complexes.

New derivatives from dehydrodieugenol B and its methyl ether displayed high anti-Trypanosoma cruzi activity and cause depolarization of the plasma membrane and collapse the mitochondrial membrane potential.

In the present work, dehydrodieugenol B (1) and its methyl ether (2), isolated from Nectandra leucantha twigs, were used as starting material for the preparation of two new derivatives (1a and 2a) containing an additional methoxycarbonyl unit on allyl side chains. Compounds 1a and 2a demonstrated activity against trypomastigotes (EC50 values of 13.5 and 23.0 µM, respectively) and against intracellular amastigotes (EC50 values of 10.2 and 6.1 µM, respectively). Additionally, compound 2a demonstrated no mammalian cytotoxicity up to 200 µM whereas compound 1a exhibited a CC50 value of 139.8 µM. The mechanism of action studies of compounds 1a and 2a demonstrated a significant depolarization of the plasma membrane potential in trypomastigotes, followed by a mitochondrial membrane potential collapse. Neither calcium level nor reactive oxygen species alterations were observed after a short-time incubation. Considering the potential of compound 2a against T. cruzi and its simple preparation from the natural product 2, isolated from N. leucantha, this compound could be considered a new hit for future drug design studies in Chagas disease.

Synthesis of resilient hybrid hydrogels using UiO-66 MOFs and alginate (hydroMOFs) and their effect on mechanical and matter transport properties.

Herein, we report the preparation of an organic-inorganic hybrid hydrogel architecture using vinyl alginate and UiO-66 MOFs (metal-organic frameworks) modified with acrylic acid (AA) UiO-66AA. UiO-66 MOFs with different crystal sizes (600, 1500, and 2500 nm) were synthesized and the effect on the mechanical and transport properties of the resulting materials, such as water absorption capacity and drug release, were evaluated. HydroMOF showed higher water absorption capacity than the pure hydrogel and enhanced mechanical properties, which depend on crystal size and the amount of UiO-66AA MOF used. The initial release rate of drug (burst release) from hydroMOFs was lower when small-sized crystals or a small amount of large-sized crystals were used; thus these are essential in changing half-life values of release rates. Finally, the cytotoxicity screening successfully showed that hydroMOFs are promising biocompatible compounds proven to have the advantages of minimized burst release and mechanical robustness.

Influence of Dimethylsulfoxide and Dioxygen in the Fructose Conversion to 5-Hydroxymethylfurfural Mediated by Glycerol's Acidic Carbon.

Both the catalytic production of 5-hydroxymethylfurfural (5-HMF) from carbohydrates and the use of a catalyst obtained from residues stand out for adding value to by-products and wastes. These processes contribute to the circular economy. In this work it was evaluated optimized conditions for 5-HMF production from fructose with high yield and selectivity. The reaction was catalyzed by an acidic carbon obtained from glycerol, a byproduct of the biodiesel industry. Special attention has been given to the use of dimethyl sulfoxide (DMSO) as a solvent and its influence on system activity, both in the presence and absence of O2. Glycerol's carbon with acidic properties can be effectively used as catalyst in fructose dehydration, allowed achieving conversions close to 100% with 5-HMF selectivities higher than 90%. The catalyst can be reused in consecutive batch runs. The influence of DMSO in the presence of O2 should be considered in the catalytic activity, as the stabilization of a reaction intermediate by the [O2:DMSO] complex is favored and, both fructose conversion and 5-HMF yield increase.

Rational production of highly acidic sulfonated carbons from kraft lignins employing a fractionation process combined with acid-assisted hydrothermal carbonization.

Highly acidic lignin-derived sulfonated carbons (LDSCs) were produced from hardwood and softwood kraft lignins under mild conditions by applying fractionation and/or pre-carbonization treatments combined with acid-assisted hydrothermal carbonization. The use of lignin fraction with higher amount oxygen, obtained from the fractionation process, resulted in carbon with the highest density of surface acid groups and improved catalytic activity. The LDSCs were successful tested in the dehydration reaction of fructose to obtain 5-hydroxymethylfurfural, and the best catalyst can be recycled without loss in its catalytic activity after perform a simple regeneration process. In contrast, the pre-carbonization step, commonly performed in several works, resulted in LDSCs with low acidity. A simple and optimized methodology for obtaining LDSCs under mild conditions was developed, and the correlations between the preparation method and the physicochemical and catalytic properties established in this work may be extendible to other starting materials for rational sulfonated carbons production.

Novel Cage-Like Hexanuclear Nickel(II) Silsesquioxane. Synthesis, Structure, and Catalytic Activity in Oxidations with Peroxides.

New hexanuclear nickel(II) silsesquioxane [(PhSiO1.5)12(NiO)6(NaCl)] (1) was synthesized as its dioxane-benzonitrile-water complex (PhSiO1,5)12(NiO)6(NaCl)(C4H8O2)13(PhCN)2(H2O)2 and studied by X-ray and topological analysis. The compound exhibits cylinder-like type of molecular architecture and represents very rare case of polyhedral complexation of metallasilsesquioxane with benzonitrile. Complex 1 exhibited catalytic activity in activation of such small molecules as light alkanes and alcohols. Namely, oxidation of alcohols with tert-butylhydroperoxide and alkanes with meta-chloroperoxybenzoic acid. The oxidation of methylcyclohexane gave rise to the isomeric ketones and unusual distribution of alcohol isomers.

Mechanism of Al(3+)-catalyzed oxidations of hydrocarbons: dramatic activation of H2O2 toward O-O homolysis in complex [Al(H2O)4(OOH)(H2O2)](2+) explains the formation of HO• radicals.

A radical mechanism of hydrocarbon oxidations with the environmentally friendly and cheap homogeneous nontransition metal system [Al(H(2)O)(6)](3+)/H(2)O(2)/MeCN-H(2)O was proposed for the first time on the basis of DFT calculations. A dramatic activation of H(2)O(2) toward homolysis in the key intermediate [Al(H(2)O)(4)(OOH)(H(2)O(2))](2+) due to the presence of the easily oxidizable OOH coligand provides, without a change of metal oxidation state, the generation of HO(•) radicals, which then oxidize hydrocarbons. Nonradical mechanisms of the olefin epoxidation with the same catalytic system were also investigated.

Extremely efficient alkane oxidation by a new catalytic reagent H(2)O(2)/Os(3)(CO)(12)/pyridine.

Triosmium dodecacarbonyl catalyzes a very efficient oxidation of alkanes by H(2)O(2) in MeCN to afford alkyl hydroperoxides (primary products) as well as alcohols and ketones (aldehydes) at 60 degrees C if pyridine is added in a low concentration. Turnover numbers attain 60,000, and turnover frequencies are up to 24,000 h(-1).