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排序方式: 共有112条查询结果,搜索用时 31 毫秒
91.
Melike alkan Sema Akay Berkant Kayan Talat Baran Dimitrios Kalderis 《Molecules (Basel, Switzerland)》2021,26(22)
In the present study, a novel heterogeneous catalyst was successfully fabricated through the decoration of palladium nanoparticles on the surface of designed Fe3O4-coffee waste composite (Pd-Fe3O4-CWH) for the catalytic reduction of nitroarenes. Various characterization techniques such as XRD, FE-SEM and EDS were used to establish its nano-sized chemical structure. It was determined that Pd-Fe3O4-CWH is a useful nanocatalyst, which can efficiently reduce various nitroarenes, including 4-nitrobenzoic acid (4-NBA), 4-nitroaniline (4-NA), 4-nitro-o-phenylenediamine (4-NPD), 2-nitroaniline (2-NA) and 3-nitroanisole (3-NAS), using NaBH4 in aqueous media and ambient conditions. Catalytic reactions were monitored with the help of high-performance liquid chromatography. Additionally, Pd-Fe3O4-CWH was proved to be a reusable catalyst by maintaining its catalytic activity through six successive runs. Moreover, the nanocatalyst displayed a superior catalytic performance compared to other catalysts by providing a shorter reaction time to complete the reduction in nitroarenes. 相似文献
92.
Ayse Nur Esen Sevilay Haciyakupoglu Sema Erenturk Marie Kubešová Jan Kučera 《Journal of Radioanalytical and Nuclear Chemistry》2016,307(1):179-185
In this study, the effect of contact time, pH, competitive cations and equilibrium study of adsorption on Slovak illite/smectite Dolná Ves was investigated. The sorption processes was studied using batch techniques under aerobic conditions with radioisotope indication using 63Ni as a radiotracer. Studied material has proved to be as promising candidate for practically used as a barrier against the spread of undesirable substances in the environment landfill as insulating material of toxic and hazardous waste. 相似文献
93.
94.
Turgut Kilic Züleyha Ozer Sagir Sema Carikci Akın Azizoğlu 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(13):2608-2612
Sideridiol (ent-7α,18β-dihydroxykaur-15-ene) one of the ent-kaurene diterpenoid, is isolated from the genus Sideritis L. belongs to the family of Lamiaceae. The vibrational frequencies of sideridiol in the ground state have been calculated using the Density Functional Theory (DFT) method with the 6-31G(d) and 6 31+G(d,p) basis sets. The calculated vibrational frequencies have been compared with that of obtained experimental IR spectrum. 相似文献
95.
Sanja Ćavar Zeljković Faik Ahmet Ayaz Huseyin Inceer Sema Hayirlioglu-Ayaz Nesrin Colak 《Natural product research》2015,29(3):293-296
This article presents the very first phytochemical investigation on new species Tripleurospermum insularum Inceer &; Hay?rl?oglu-Ayaz. The volatile profile of odorous parts of the plant was analysed by GC/MS, and compounds were identified in headspace and essential oil obtained from aerial parts, representing 70.81% and 92.44% in total, respectively. The major volatiles were n-alkanes (38.43–59.22%), while essential oil was also rich in globulol (13.45%) and β-sesquiphellandrene (9.29%). The content of phenolic compounds in methanolic extract and oil was 3621.62 and 14.4 mg GAE/100 g of dry plant, respectively. Moreover, potential medicinal effects were found in mean of antioxidant activity of this plant measured by using two different assays: radical-scavenging activity and ferric-reducing activity. Samples revealed values ranging from 0.33 to 146.80 μmol TE/100 g for DPPH assay, and from 2.29 to 5414.17 μmol AAE/100 g for FRAP assay. 相似文献
96.
97.
Lokman Uzun Deniz Türkmen Erkut Ylmaz Sema Bekta Adil Denizli 《Colloids and surfaces. A, Physicochemical and engineering aspects》2008,330(2-3):161-167
The aim of this study was to investigate the performance of monoliths composed of hydroxyethyl methacrylate (HEMA) to which N-methacryloyl-(L)-cysteine methyl ester (MAC) was polymerized for removal of heavy metal ions. Poly(HEMA-MAC) monolith was produced by bulk polymerization. Poly(HEMA-MAC) monolith was characterized by FTIR and scanning electron microscopy (SEM). The poly(HEMA-MAC) monolith with a swelling ratio of 89%, and containing 69.4 μmol MAC/g were used in the adsorption studies. Adsorption capacity of the monolith for the metal ions, i.e., Cu2+, Cd2+, Zn2+, Hg2+, and Pb2+ were investigated in aqueous media containing different amounts of the ions (10–750 mg/L) and at different pH values (3.0–7.0). The maximum adsorption capacities of the poly(HEMA-MAC) monolith were 68.2 mg/g for Zn2+, 129.2 mg/g for Cu2+, 245.8 mg/g for Pb2+, 270.2 mg/g for Hg2+, and 284.0 mg/g for Cd2+. pH significantly affected the adsorption capacity of MAC incorporated monolith. The competitive adsorption capacities were 587 μmol/g for Zn2+, 1646 μmol/g for Cu2+, 687 μmol/g for Pb2+, 929 μmol/g for Hg2+, and 1993 μmol/g for Cd2+. The chelating monolith exhibited the following metal ion affinity sequence on molar basis: Cd2+ > Cu2+ > Hg2+ > Pb2+ > Zn2+. The formation constants of MAC–metal ion complexes have been investigated applying the method of Ruzic. The calculated values of stability constants were 5.28 × 104 L/mol for Cd2+, 4.16 × 104 L/mol for Cu2+, 2.27 × 104 L/mol for Hg2+, 1.98 × 104 L/mol for Pb2+, and 1.25 × 104 L/mol for Zn2+. Stability constants were increased with increasing binding affinity. The chelating monoliths can be easily regenerated by 0.1 M HNO3 with higher effectiveness. These features make poly(HEMA-MAC) monolith a potential adsorbent for heavy metal removal. 相似文献
98.
Azo-hydrazone tautomerism in azo dyes has been modeled by using density functional theory (DFT) at the B3LYP/6-31+G(d,p) level of theory. The most stable tautomer was determined both for model compounds and for azo dyes Acid Orange 7 and Solvent Yellow 14. The effects of the sulfonate group substitution and the replacement of the phenyl group with naphthyl on the tautomer stability and on the behavior in solvent have been discussed. Intramolecular hydrogen bond energies have been estimated for the azo and hydrazone tautomers to derive a relationship between the tautomer stability and the hydrogen bond strength. The transition structures for proton transfer displayed resonance assisted strong hydrogen bonding properties within the framework of the electrostatic-covalent hydrogen bond model (ECHBM). Evolution of the intramolecular hydrogen bond with changing structural and environmental factors during the tautomeric conversion process has been studied extensively by means of the atoms-in-molecules (AIM) analysis of the electron density. The bulk solvent effect was examined using the self-consistent reaction field model. Special solute-solvent interactions were further investigated by means of quantum mechanical calculations after defining the first-solvation shell by molecular dynamics simulations. The effect of cooperative hydrogen bonding with solvent molecules on the tautomer stability has been discussed. 相似文献
99.
100.
Sabriye Yusan Mahmoud A. A. Aslani D. Alkim Turkozu Hasan A. Aycan Sule Aytas Sema Akyil 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(1):231-238
In this work, sorption of uranium ions on volcanic tuff collected from the deposits located at the Tendurek of Eastern Turkey
was investigated in batch technique. The effect of different parameters such as pH of the medium, contact time, uranium concentration
and temperature were investigated. The maximum removal of U(VI) was found to be 68% at pH 5.0, initial U(VI) concentration
of 75 mg L−1 and 30 °C. Thermodynamic parameters, such as enthalpy of adsorption ∆H°, free energy change ∆G° and entropy change ∆S° have been also calculated and interpreted. The suitability of the Langmuir, Freundlich and Dubinin-Radushkhevic adsorption
models to the equilibrium data was investigated for uranium-volcanic tuff system. The results suggest that volcanic tuff can
be used as efficient and cost effective adsorbents for uranium ion removal. 相似文献