Trapping of Ag+, Cu2+, and Co2+ by faujasite zeolite Y: new interpretations of the adsorption mechanism via DFT and statistical modeling investigation

This work evaluated the potential of a synthesized faujasite-type zeolite Y as an adsorbent for the removal of relevant heavy metals such as silver (Ag+), copper (Cu2+), and cobalt (Co2+). The adsorption data of Ag+, Cu2+, and Co2+ ions were determined experimentally at pH 6 and temperatures of 298, 308, and 318 K. Two theoretical approaches have been applied based on statistical physics modeling and density functional theory (DFT) to understand and characterize the ion exchanges involved in the removal of all metals. Results showed that this zeolite was more efficient for the adsorption of Ag+ via cation-exchange. Based on the physical modelling, the removal of heavy metals on this zeolite was mono and multi-ionic (simple and multi-interactions), where the ions interacted via one and two adsorption sites. It was also noted that the temperature increment generated more available functional groups of the zeolite, facilitating the access to the smaller cavities and the interactions with the adsorbent. Adsorption energies for removing these metals with tested zeolite were slightly endothermic and were consistent with the typical values reported for ion exchange systems of heavy metals + zeolites. DFT results demonstrated that these cationic exchange energies depend on the nature of precursor salt, but with the same ranking. Both statistical and DFT approaches agreed that exchange Ag+ in zeolite Y was easier than Cu2+ and Co2+. Overall, the application of both theoretical approaches provided a reliable interpretation of the adsorption mechanism

Ab Initio Screening of Zeolite Y Formulations for Efficient Adsorption of Thiophene in Presence of Benzene

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Study on the biological behaviors of Ca-P coatings with different morphology on carbon/carbon composites

In this work, we designed and fabricated a Ca-P composite bio-coating with different surface morphologies on a carbon/carbon (C/C) matrix by means of hybrid supersonic atmospheric plasma spraying (SAPS) and microwave-hydrothermal (MH) technologies. We found that all studied coating materials can support mesenchymal stem cells (MSCs) proliferation with prolonged culture time (3 days and 7 days) in vitro. Furthermore, according to the (Confocal Laser Scanning Microscopy) CLSM results, the MSCs also showed good attachment and different spreading morphologies on SAPS/MH coatings. As such, C/C matrix, the MH treated coatings with needle-like and rod-like microstructures were chosen for further in vivo investigation. Considering the good bonding between host tissue and the studied materials, the in vivo morphology studies confirmed a good histocompatibility for all coating samples, as well as a decreasing expression for inflammatory factors in a physiological environment. The histological results around the implants indicated different cell aggregation and vascularization ability in the local micro-environment. In particular, based on the reduction of the C/C initial surface flaws (e.g. hydrophobicity, biological inertia and easily producing carbon fragments or particles), the MH treated coating with rod-like surface morphology with a specific surface area (similar to 2.33 m(2)/g) and roughness (similar to 13.80 mu m), showed excellent performance as a promising implant in live tissue

Dibenzyl Disulfide Adsorption on Cationic Exchanged Faujasites: A DFT Study

Although dibenzyl disulfide (DBDS) is used as a mineral oil stabilizer, its presence in electrical transformer oil is associated as one of the major causes of copper corrosion and subsequent formation of copper sulfide. In order to prevent these undesirable processes, MY zeolites (with M = Li, Na, K, Cs, Cu or Ag) are proposed to adsorb molecularly DBDS. In this study, different MY zeolites are investigated at the DFT+D level in order to assess their ability in DBDS adsorption. It was found that CsY, AgY and CuY exhibit the best compromise between high interaction energies and limited S-S bond activation, thus emerging as optimal adsorbents for DBDS

A molecular understanding of citrate adsorption on calcium oxalate polyhydrates

Calcium oxalate precipitation is a common pathological calcification in the human body, whereby crystallite morphology is influenced by the chelating properties of biological ions such as citrate. It has been suggested that citrate could steer oxalate formation towards its dihydrated form and away from the monohydrated form, which was identified as a major cause for disease. To assess the influence of the citrate ion on the resulting calcium oxalate, surface energies were calculated at the dispersion-corrected density functional level of theory for both monohydrated and dihydrated calcium oxalate. Different adsorption geometries were considered by varying the attacking angle of citrate as well as by considering the citrate ion on top of an adsorbed water layer or penetrating the water layer. The obtained results were compared to ab initio molecular dynamics simulations and experimental scanning electron microscope images. A strong preference for citrate adsorption on calcium oxalate dihydrate was observed, suggesting medical applications for the treatment of such pathological calcifications