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Li6ZnO4 was chemically modified by nickel addition, in order to develop different compositions of the solid solution Li6Zn1-xNixO4. These materials were evaluated bifunctionally; analyzing their CO2 capture performances, as well as on their catalytic properties for H2 production via dry reforming of methane (DRM). The crystal structures of Li6Zn1-xNixO4 solid solution samples were determined through X-ray diffraction, which confirmed the integration of nickel ions up to a concentration around 20 mol%, meanwhile beyond this value, a secondary phase was detected. These results were supported by XPS and TEM analyses. Then, dynamic and isothermal thermogravimetric analyses of CO2 capture revealed that Li6Zn1-xNixO4 solid solution samples exhibited good CO2 chemisorption efficiencies, similarly to the pristine Li6ZnO4 chemisorption trends observed. Moreover, a kinetic analysis of CO2 isothermal chemisorptions, using the Avrami-Erofeev model, evidenced an increment of the constant rates as a function of the Ni content. Since Ni2+ ions incorporation did not reduce the CO2 capture efficiency and kinetics, the catalytic properties of these materials were evaluated in the DRM process. Results demonstrated that nickel ions favored hydrogen (H2) production over the pristine Li6ZnO4 phase, despite a second H2 production reaction was determined, methane decomposition. Thereby, Li6Zn1-xNixO4 ceramics can be employed as bifunctional materials.

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The development of new materials that have a high capacity to remove pollutants in water-based media is becoming increasingly important because of the serious contamination of water and the negative impact on biodiversity and public health. The presence of glyphosate in water, the most widely used herbicide worldwide, has triggered alerts owing to the collateral effects it may cause on human health. The main objective of the present study was to investigate the potential of the hybrid material MIL-53(Al)@RH for the adsorption of glyphosate in aqueous solution. The material was obtained following the methodology of MIL-53(Al) synthesis in the presence of hydrolyzed rice husk assisted by microwave. Batch adsorption experiments were carried out to evaluate the adsorbent dosage, pH0 solution effect, contact time, adsorbate concentration, and temperature effect. The results demonstrated that a maximum adsorption capacity of 296.95 mg g-1, at pH0 4 with a ratio of 0.04 g MIL-53(Al)@RH/50 mL of solution, was achieved in 30 min. The Avrami and pseudo-second order models appropriately described the adsorption kinetics and the equilibrium by Langmuir and Sips models. The enthalpy changes (ΔH°) determined propose an endothermic reaction governed by chemisorption, corroborating the kinetic and equilibrium settings. Hydrogen bonds, π*-π interactions, and complexation between the metal centers of MIL-53(Al) and the anionic groups of glyphosate were postulated to be involved as adsorption mechanisms. Finally, for practical application, MIL-53(Al)@RH was packed in a column for a fixed-bed test which revealed that the hybrid can remove glyphosate with an adsorption capacity of 76.304 mg L-1, utilizing 90% of the bed.

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In recent years, the popularity of metal hydrides has increased considerably for hydrogen storage and their applications in hydrogen fuel cells. Their potential applications for clean energy are promissory. However, the temperatures required for adsorption and desorption are extremely high, which range between 500 and 700 K, making their use impractical. To overcome these difficulties, the following work considers using three hydride alloys: magnesium-aluminum (MgAl), magnesium-nickel (MgNi), and magnesium-zinc (MgZn). The Mg concentrations were set to be between 80 and 100 wt% in order to reduce the temperatures of adsorption and desorption in contrast with the temperatures of pure magnesium. The chemisorption and repulsion energies of the hydrogen molecule on the surface (110) of the different metallic alloys were studied at 0, 200, 400, 600, and 700 K, respectively. The study was based on the density functional theory (DFT), with the module DMol3 of the molecular simulation program Materials Studio, which was used to obtain these energy values. The results confirm that adding aluminum, nickel, or zinc into magnesium matrix increases the chemisorption and decreases the energy repulsion values on surfaces of the metallic alloys, improving the effectiveness of the hydrogen storage.

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The quaternization of chitosan molecules creates materials with high adsorptive capacity towards textile dyes, which renders them capable of rapidly removing such dyes from a solution. In this study, a novel material was synthesized in bead form to adsorb the Acid Blue 25 textile dye. The adsorption isotherms, kinetics, and thermodynamics of this new material were investigated. The beads were further characterized by FT-IR and SEM studies, as well as their rheological behavior. Bioassays with Daphnia similis analyzed the toxicity of the dye before and after treatments. The Freundlich isotherm model fitted to all the adsorption data in a pH range from 2.50 to 8.50. Kinetic studies showed that adsorption was ruled by an intraparticle diffusion process and reached equilibrium in 270 min, as 39.527 µg mg-1 of dye was sorbed to the beads. Thermodynamic studies showed that adsorption was a spontaneous and endothermic process. Thermodynamics also confirmed that the adsorption was proportionally influenced by higher temperatures. The FT-IR spectroscopy identified the adsorbate/adsorbent binding sites, thus confirming the occurrence of chemisorption. Post-treatment bioassays found a significant decrease in toxicity, obtaining just 10% of D. similis mortality after adsorption treatments. Therefore, the synthesized beads from this research can potentially be applied to the treatment of textile effluents.

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Li2CuO2 and different iron-containing Li2CuO2 samples were synthesized by solid state reaction. On iron-containing samples, atomic sites of copper are substituted by iron ions in the lattice (XRD and Rietveld analyses). Iron addition induces copper release from Li2CuO2, which produce cationic vacancies and CuO, due to copper (Cu2+) and iron (Fe3+) valence differences. Two different physicochemical conditions were used for analyzing CO2 capture on these samples; (i) high temperature and (ii) low temperature in presence of water vapor. At high temperatures, iron addition increased CO2 chemisorption, due to structural and chemical variations on Li2CuO2. Kinetic analysis performed by first order reaction and Eyring models evidenced that iron addition on Li2CuO2 induced a faster CO2 chemisorption but a higher thermal dependence. Conversely, CO2 chemisorption at low temperature in water vapor presence practically did not vary by iron addition, although hydration and hydroxylation processes were enhanced. Moreover, under these physicochemical conditions the whole sorption process became slower on iron-containing samples, due to metal oxides presence.

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Background: Textile and dye industries pose a serious threat to the environment. Conventional methods used for dye treatment are generally not always effective and environmentally friendly. This drove attention of scores of researchers to investigate alternative methods for the biodegradation of dyes using fungal strains. In this work, white-rot fungus (Panus tigrinus) was used as a biosorbent for the decolorization of Reactive Blue 19. The process parameters that were varied were initial concentration (50­150 mg/L), contact time (30­90 min), and pH (2­6). In addition, to gain important data for the evaluation of a sorption process, the equilibrium and kinetics of the process were determined. Results: White-rot fungus showed great potential in decolorizing Azo dyes. The strain showed the maximum decolorization of 83.18% at pH 2, a contact time of 90 min, and an initial concentration of 50 mg/L. The Langmuir isotherm described the uptake of the Reactive Blue 19 dye better than the Freundlich isotherm. Analysis of the kinetic data showed that the dye uptake process followed the pseudo second-order rate expression. Conclusion: The biosorption process provided vital information on the process parameters required to obtain the optimum level of dye removal. The isotherm study indicated the homogeneous distribution of active sites on the biomass surface, and the kinetic study suggested that chemisorption is the rate-limiting step that controlled the biosorption process. According to the obtained results, P. tigrinus biomass can be used effectively to decolorize textile dyes and tackle the pollution problems in the environment.

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In this work the adsorption of the antibiotics levofloxacin (LV), tetracycline (TC) and benzylpenicillin (BP) on the surface of silver nanoparticles (AgNP) have been investigated through both surface-enhanced Raman scattering (SERS) and UV-VIS-NIR spectroscopies. The SERS spectra were obtained using 1064 nm exciting radiation. Theoretical models for the antibiotic molecules were obtained from DFT calculations, and used in the vibrational assignment. The adsorption geometries were proposed based on the changes in the spectral patterns. The LV compound adsorbs through carboxylate group, TC compound interacts with silver atoms through carbonyl from intermediate ring, and BP compound adsorbs by carbonyl moieties from carboxylate and acyclic amide.

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