The literature devoted to numerical investigation of adsorption of heavy metal ions on carbon nanotubes is scarce. In this paper molecular dynamics is used to simulate the adsorption process and to investigate the effect of the infl uencing parameters on the rate of adsorption. The predictions of the molecular dynamics simulation show that the adsorption process is improved with increasing the temperature, pH of solution, the mass of nanotubes, and surface modifi cation of CNT using hydroxyl and carboxyl functional groups. The results predicted by the model are compared with the experimental results available in the literature; the close agreement validates the accuracy of the predictions. This study reveals that the water layers around the carbon nanotubes and the interaction energies play important roles in the adsorption process. The study also shows that electrostatic force controls the attraction of zinc ions on the nanotube sidewall.
New emerging approaches in tissue engineering include incorporation of metal ions involved in various metabolic processes, such as Cu, Zn, Si into bioceramic scaffolds for enhanced cell growth and differentiation of specific cell types. The aim of the present work was to investigate the attachment, morphology, growth and mineralized tissue formation potential of Dental Pulp Stem Cells (DPSCs) seeded into Mg-based glassceramic scaffolds with incorporated Zn and Cu ions. Bioceramic scaffolds containing Si 60%, Ca 30%, Mg 7.5% and either Zn or Cu 2.5%, sintered at different temperatures were synthesized by the foam replica technique and seeded with DPSCs for up to 21 days. Scanning Electron Microscopy with associated Energy Dispersive Spectroscopy (SEM-EDS) was used to evaluate their ability to support the DPSCs’s attachment and proliferation, while the structure of the seeded scaffolds was investigated by X-Ray Diffraction Analysis (XRD). Zn-doped bioceramic scaffolds promoted the attachment and growth of human DPSCs, while identically fabricated scaffolds doped with Cu showed a cytotoxic behaviour, irrespective of the sintering temperature. A mineralized tissue with apatite-like structure was formed on both Cu-doped scaffolds and only on those Zn-doped scaffolds heat-treated at lower temperatures. Sol-gel derived Zn-doped scaffolds sintered at 890oC support DPSC growth and apatite-like tissue formation, which renders them as promising candidates towards dental tissue regeneration.
Chinese loess. J. Hazard. Mater. 161(2), 824–834. DOI: 10.1016/j.hazmat.2008.04.059. 28. Puigdomenech, I. (2010). Make Equilibrium Diagrams Using Sophisticated Algorithms (MEDUSA) , Royal Institute of Technology, Inorganic Chemistry. 10644 stockolm Sweden. firstname.lastname@example.org 29. Su, Q., Pan, B., Wan, S., Zhang, W. & Lv, L. (2010). Use of hydrous manganese dioxide as potential sorbent for selective removal of lead cadmium and zincions from water. J. Colloid Interf. Sci. 349(2), 607–612. DOI: 10.1016/j.jcis.2010.05.052.
human seminal spermatozoa: characterization and effects on cell membranes. Arch Androl 1989, 23, 97-103. 28. Sirivaidyapong S., Ursem P., Bevers M.M., Colenbrander B.: Effect of prostatic fluid on motility, viability and acrosome integrity of chilled and frozen-thawed dog spermatozoa. J Reprod Fertil 2001, 57 Suppl, 383-386. 29. Strzezek J., Hopfer E., Zaborniak A.: Zincion dependent protein in boar semen. II. Effects on sperm motility and antibacterial properties. Anim Reprod Sci 1987, 13, 133-142. 30. Strzezek R., Fraser L.: Characteristics of spermatozoa of whole
The influence of the preparation method of samples on the zinc ions sorption parameters in Spirogyra sp. algae was analysed. The Zn2+ sorption process from the salt solutions of this analyte was carried out in static conditions. The carried out analyses results show that the method of algae samples preparation for analyses (thermal drying, freeze drying, samples conditioning in demineralised water) and storage period influence their sorption capacity. On the basis of the carried out research of the metal sorption kinetics in live and prepared algae samples, it was found that the equilibrium is achieved after approximately 30 min. In the experiment conditions, 56% of metals are sorbed in live algae during the first 15 min. Approximately 17 and 65% of zinc ions present in the dilution accumulated in thermally dried and freeze dried algae samples respectively after 30 min of the process. It was confirmed that conditioning of the algae samples in demineralised water, prior to the sorption process, increases its efficiency. In order to define sorption capacity of freeze dried Spirogyra sp. algae, the Langmuir isotherm model was applied. It was found out that algae absorb heavy metals in proportion to their content in a solution, in which they were immersed. The sorption capacity of freeze dried Spirogyra sp. algae and zinc, defined with the use of the Langmuir isotherm, shows considerable imprecise result. Evident influence of hydrogen cations on zinc concentrations in algae and in the solution in the state of equilibrium was found out.
Saccharomyces cerevisiae, waste biomass originated from beer fermentation industry, was used to remove metal ions from four copper-containing synthetic effluents: Cu-Fe, Cu-Fe-Ni, Cu-Fe-Zn, and Cu-Fe-Ni-Zn. The characterization of the biomass surface was investigated by Scanning Electron Microscopy and Fourier-transform Infrared Spectroscopy. The adsorption behavior of Saccharomyces cerevisiae for copper, iron, nickel and zinc ions in aqueous solution was studied as a function of pH, initial copper concentration, equilibrium time, and temperature. Langmiur, Freundlich, Temkin and Dubinin-Radushkevich equilibrium models have been assessed to describe the experimental sorption equilibrium profile, while pseudo-first order, pseudo-second order, Elovich and the intra-particle diffusion models were applied to describe experimental kinetics data. Maximum sorption capacities have been calculated by means of Langmuir equilibrium model and mean free sorption energies through the Dubinin-Radushkevich model. Thermodynamic analysis results showed that the adsorption of copper, iron and zinc was spontaneous and endothermic in nature, while of nickel exothermic. Saccharomyces cerevisiae can be successfully applied for complex wastewater treatment.
Polycrystalline ferrites having the chemical formula Ni0.65−xZn0.35MgxFe2O4 (0 ⩽ x ⩽ 0.2) were prepared by solid state reaction route in steps of x = 0.04. The effect of incorporation of diamagnetic divalent magnesium at expense of nickel on the structural properties of these ferrites has been studied. The proposed cation distribution was derived from theoretical X-ray diffraction intensity calculations. These intensity calculations were done by varying the concentration of magnesium ions over two sites in the lattice. For a certain amount of magnesium concentration, the calculated and observed X-ray diffraction intensities were found to be in good agreement. Site occupancy of divalent diamagnetic magnesium was established from this cation distribution. The octahedral environment facilitates magnesium to enter the B-site at about 95 % and the remaining 5 % occupy tetrahedral sites (A-sites). The movements of cations between tetrahedral and octahedral sites as a result of magnesium substitution were discussed in the view of structural parameters, such as tetrahedral and octahedral bond lengths, cation-cation and cation-anion distances, bond angles and hopping lengths, which were calculated using experimental lattice constants and oxygen parameters. All structural parameters showed slight deviations from ideal values. Among all magnesium substituted samples, the ones with x = 0.12 exhibited insignificant variation in view of structural properties. Dielectric measurements were conducted at a standard frequency of 1 kHz. Large values of the recorded dielectric constants displayed typical characteristics of bulk ferrites. Both dielectric constant and loss values showed mixed variations, attributed to the loss of zinc ions during the sintering process.
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