Display omitted
•Bimetallic and monometallic Cu, Fe and Mn exchanged ZSM-5 zeolites were prepared.•Adsorption of CO and N2O was studied using calorimetry and in situ FTIR spectroscopy.•Synergetic ...effect was observed in CO adsorption on bimetallic samples containing Cu.•N2O adsorption is restricted on the cation exchanged the first.
Room temperature adsorption of CO and N2O using isothermal calorimetry and in situ FTIR spectroscopy on bimetallic and monometallic forms of Cu, Fe and Mn exchanged zeolite ZSM-5 was studied. The two complementary techniques allowed the assessment of the strengths of interactions as well as the identification of the cations active in adsorption. In bimetallic samples containing Cu, a synergistic effect was observed for CO adsorption, i.e higher strengths of adsorption were detected than for corresponding monometallic samples. Such an effect was not detected for N2O. Furthermore, FTIR measurements revealed that N2O adsorption was somewhat restricted for the cation which was introduced the first in bimetallic samples. These findings imply the importance of the order of cation introduction and the procedure of ion exchange process for the adsorptive properties of bimetallic ZSM-5 and, consequently, catalytic reactions where adsorption of N2O is an important reaction step.
Poisoning effects by alkali metal chlorides is one of the major reasons for the deactivation of SCR catalyst in biomass-fired plants. In this study, the influence of KCl on two vanadium-based ...catalysts with different promoters, V2O5-WO3/TiO2 and V2O5-Ce(SO4)2/TiO2, was investigated. The catalytic activity of the fresh V2O5-WO3/TiO2 was higher than that of V2O5-Ce(SO4)2/TiO2 at low temperatures. V2O5-Ce(SO4)2/TiO2 performed better than V2O5-WO3/TiO2 when KCl was deposited on the catalyst surface. Both poisoned catalysts were efficiently regenerated by SO2 treatment. The characterization results show that the reducibility and acidity of the catalysts were weakened by KCl deposition but regenerated by SO2.
The possibility of removal of pharmaceutically active substances, atenolol, diclofenac sodium and salicylic acid, from water solutions using hierarchical form of zeolite ZSM-5 is investigated in this ...paper. Mesopore formation in ZSM-5 was achieved using alkaline treatment. Zeolitic samples were characterized by X-ray diffraction, low temperature nitrogen adsorption, solid-state 27Al MAS NMR, point of zero charge determination and microcalorimetry – volumetry of ammonia adsorption. Adsorption isotherms of pharmaceutically active substances were obtained and liquid calorimetric experiments were used to evaluate the strength of interactions. The capacity for salicylic acid adsorption measured for the mesoporous sample did not significantly differ from the results obtained for the parent ZSM-5. However, in the case of atenolol and diclofenac sodium, mesoporous ZSM-5 exhibited increased adsorption capacities. Calorimetric data revealed higher heats of atenolol adsorption on mesoporous ZSM-5, compared to the parent. Based on similar acidity and surface charge determined for the two samples, our results show that geometry and dimensions of both zeolite pores and adsorbing molecules play a crucial role in the studied adsorption processes and that tailoring ZSM-5 porosity by desilication can be used to expand its applicability in depollution processes.
Catalytic materials are the greatest challenge for the commercial application of water electrolysis (WEs) and fuel cells (FCs) as clean energy technologies. There is a need to find an alternative to ...expensive and unavailable platinum group metal (PGM) catalysts. This study aimed to reduce the cost of PGM materials by replacing Ru with RuO
2
and lowering the amount of RuO
2
by adding abundant and multifunctional ZnO. A ZnO@RuO
2
composite in a 10:1 molar ratio was synthesized by microwave processing of a precipitate as a green, low-cost, and fast method, and then annealed at 300°C and 600°C to improve the catalytic properties. The physicochemical properties of the ZnO@RuO
2
composites were investigated by X-ray powder diffraction (XRD), Raman and Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The electrochemical activity of the samples was investigated by linear sweep voltammetry in acidic and alkaline electrolytes. We observed good bifunctional catalytic activity of the ZnO@RuO
2
composites toward HER and OER in both electrolytes. The improved bifunctional catalytic activity of the ZnO@RuO
2
composite by annealing was discussed and attributed to the reduced number of bulk oxygen vacancies and the increased number of established heterojunctions.
Two different ways of extracting antioxidative compounds (including soluble polyphenols) from rusks made from wheat flour with added millet (Panicum miliaceum L.) were compared, i.e., solvent ...extraction and in vitro digestion. Wheat flour was replaced by millet flour in amounts of 10, 20 or 30 wt. % (per dry mass). Solvent extraction was realized using a mixture of ethanol and water in different percentages, with or without the addition of formic acid. The total content of phenolic compounds (TPC) was determined using Folin? ?Ciocalteu reagent, while the antioxidative capacity was measured by the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. The efficiency of solvent extraction was enhanced by the addition of formic acid. The addition of millet flour in amounts up to 20 % enhanced the antioxidative properties. It was shown that in vitro digestion was more efficient in the extraction of antioxidative compounds, in comparison with solvent extraction.
Keeping of red wine in bottles is very important for its maturation and quality. However, there are numerous changes that happen during that period, usually caused by oxidative processes and changes ...in structure and content of polyphenolic compounds. The goal of this study was to determine the effects of Inactivated dry yeast (IDY) products on aging, phenolics content, colour stability and sensory characteristics of red wine Prokupac (Serbian autochthonous variety). The treatment of wine was done by 3 different IDYP (Lallemand, Canada): Optimum White, Opti Less and Noblesse, applied as 0.2 g/L and 0.4 g /L during 15 days. Subsequently, wine clarification was done, followed by filtration and bottling. Untreated wines were used for comparison. Wine was subjected to accelerated aging (10 days at 55 ° C) and also to normal aging conditions during one year. To determine the influence of IDYP following parameters were monitored: dissolved O2, free and total SO2, sugar free extract, content of total phenolics, flavonoids, flavan-3-ols and anthocyanins, percent of polymeric color, color tint, color intensity and sensory characteristics (Panel method). The obtained results clearly show that IDY products are good scavengers of oxygen and have a positive impact on wine quality preservation and its organoleptic characteristics. However, a slight decrease of polyphenols content was detected.
Besides its importance concerning fundamental studies on gas adsorption in
narrow pores, investigation of commensurate freezing of fluid within the
zeolite is of practical importance in application ...of zeolite in the process
of adsorption, separation and catalysis. In this work the adsorption of
n-hexane on HZSM-5 and its transition metal ion-exchanged modified forms was
studied at 303 K by means of microcalorimetry. The thermal molar entropies of
adsorption were calculated and thus, the freezing like behaviour of n-hexane
inside the structure of zeolite as a confinement media was noticed. This
effect is governed by the attractive interactions between n-hexane molecules
and the pore walls, and is also influenced by the length of the pores and the
nature of charge-balancing cations. Among the investigated zeolites, solid
like phase of n-hexane in the pores of zeolites with Fe2+ ions is the most
like a solid n-hexane bulk, while the presence of Cu2+ ions contribute to the
lowest ordering obtained solid like phase of n-hexane.
•Pharmaceutically active compounds are adsorbed on commercial activated carbons.•Activated carbons differ in terms of their textural and surface characteristics.•The heats of interactions were ...measured by means of calorimetry.•The adsorption is controlled mostly by textural characteristics of activated carbons.•Activated carbons’ acid/base features are of significance for adsorption.
In this study, the adsorption of pharmaceutically active compounds – salicylic acid, acetylsalicylic acid, atenolol and diclofenac-Na onto activated carbons has been studied. Three different commercial activated carbons, possessing ∼650, 900 or 1500m2g−1 surface areas were used as solid adsorbents. These materials were fully characterized – their textural, surface features and points of zero charge have been determined.
The adsorption was studied from aqueous solutions at 303K using batch adsorption experiments and titration microcalorimetry, which was employed in order to obtain the heats evolved as a result of adsorption. The maximal adsorption capacities of investigated solids for all target pharmaceuticals are in the range of 10−4molg−1. The obtained maximal retention capacities are correlated with the textural properties of applied activated carbon. The roles of acid/base features of activated carbons and of molecular structures of adsorbate molecules have been discussed. The obtained results enabled to estimate the possibility to use the activated carbons in the removal of pharmaceuticals by adsorption.
Zeolites can mitigate ammonium losses to the environment by taking up the ions from sources such as farmyard manure and ammonium-bearing fertilizers. This ability can improve nitrogen fertilizing ...practice given that ammonium ions loaded onto zeolite are available for plant uptake. The main goal of this study was to assess the influence of zeolite (clinoptilolite) and ammonia-loaded clinoptilolite on growth and yield of red clover (Trifolium pratense L.), as well as their influence on the microbial dynamics in soil. Plants sown in pots were cut four times, and dry matter yield (DM) of each harvest was weighed. The number of culturable bacteria, moulds, ammonifiers, Azotobacter sp. and actinomycetes was determined at the beginning of the experiment, and after each harvest. Two control treatments (soil without fertilizer and soil supplemented with mineral fertilizer - CAN) were included in the study. The application of ammonia-loaded clinoptilolite positively and significantly affected the microbial activity and provided higher yields (from 4.9 g/pot in ammonia-loaded clinoptilolite treatment to 4.3 g/pot in soil with zeolite treatment). Our results suggest that the addition of clinoptilolite to organic fertilizers (manure, composts) could be recommended. The increase of microbial communities’ abundances and their activity represented the key benefit from clinoptilolite application.
PDF
