Papers by Keyword: Zinc

Abstract: A novel Zn biodegradable composite was produced by direct extrusion of Zn powders at room temperature. The powders were efficiently consolidated to a high relative density, and the composite reached a UTS higher than 120 MPa and elongation of almost 70%. Microstructural observations showed ultra-fine Zn grains decorated by well-dispersed ZnO clusters at the grain boundaries. The degradation behavior of the composite and an as-cast Zn reference accessed by immersion tests in HBSS for both materials were similar and gave an equivalent corrosion rate. Additional static immersion tests in DMEM + 5% FSB showed a similar corrosion rate (0.015 mm/y), but SEM analysis of the corroded surface suggested that the degradation process of each as-cast or DE consolidated composite differs. MTT assays with extracts of both as-cast and extruded composites showed similar cytotoxicity, which was dependent on the dilution of the extracts. It was concluded that the proposed methodology brings the potential for an interesting solution to produce a sound Zn-ZnO composite with good biocompatibility, satisfactory corrosion rate, and high yield strength.

Abstract: Today environmental aspects are of great importance in the sustainability of the planet, in this aspect anti-corrosive treatments facilitate the durability of metal structures. Among the most widely used anticorrosive metals is Zinc and its alloys. In the deep galvanizing process of large steel structures, tanks containing Zinc in a molten state at a temperature of 460 °C are necessary. Then, to protect elements that are too large or that need to be treated "in situ", metallization is used, which consists of projecting molten zinc wire on the metal surface that has previously been subjected to a process sandblasting (mechanical abrasion). The two main methods of metalizing are electric arc and flame. In the present work an industrial wiredrawing draft has been studied, determining the drawing force and the power required in each stage. For this purpose, linear strain hardening model vs non-linear strain hardening model that takes strain rate hardening into account has been proposed for its implementation in the analytical model of the process and finite element model (FEM) has been developed too. The use of Hall Petch equation has been allowed to get a prediction of the evolution of the grain size during the wiredrawing sequence.

Abstract: Chitosan/Alginate Nanoparticles (CANPs) were produced via microemulsion method. SEM images captured that CANPs has rough, irregular, and porous surfaces. The particle sizes were in the range of 1-15 nm with an average diameter of 8.31 nm. CANPs were applied for trace metals removal. Optimum adsorption capacity of Zn(II) and Cu(II) were 8.144 and 5.582 mg g^-1, respectively. Kinetic studies show that the adsorption of Zn(II) and Cu(II) onto CANPs fitted pseudo second order model. Isotherm studies determined that the sorption followed Dubinin-radushkevich model. Zn(II) adsorbed CANPs (Zn/CANPs) and Cu(II) adsorbed CANPs (Cu/CANPs) were investigate their antibacterial activity againts E. coli and S. aureus. Zone of Inhibition (ZOI) of Zn/CANPs were 19.3 mm (E. coli) and 17.5 mm (S. aureus). ZOI of Cu/CANPs were 14.17 mm (E. coli) and 10.75 mm (S. aureus). The results revealed that CANPs were a promising bifunctional material for metals removal and has good antibacterial activity.

Abstract: In this work, zinc nanoparticles were obtained. As a production method, a one-stage induction flow levitation method was used. The starting material was spherical granules with a purity of 99.9% and a mass of 2 g; as atoms evaporated from the surface of the molten granule, the drop was fed with a metal wire made of the same material. The productivity of the nanoparticles was 30 g / h. The resulting nanoparticles were characterized by scanning electron microscopy, X-ray phase analysis, porosimetry, and inductively coupled plasma atomic emission spectroscopy.

Abstract: The synthesis of zinc-substituted cobalt ferrite (Co_0.9Zn_0.1Fe₂O₄) using the sol gel method has been successfully carried out. The thermogravimetric analysis and differential thermal analyzer curve shows that at 400°C the Co_0.9Zn_0,1Fe₂O₄ sample has formed the final phase of nanoparticles. Therefore, the modification of physical properties was carried out by annealing treatment at temperature of 450°C, 550°C, 650°C, and 750°C. The X-rays diffraction show that all samples are in a single phase with a face center cubic space group Fd-3m structure according to the ICDD 221086. The crystal size increased with the annealing temperature 33.69 nm to 45.88 nm. The Co_0.9Zn_0.1Fe₂O₄ showed as excellent antibacterial properties on Staphylococcus aureus and Escherichia coli. The most superior antibacterial activity to Staphylococcus aureus was Co_0.9Zn_0,1Fe₂O₄ sample which was annealed at 650°C with a clear zone diameter of 39.81 mm. Meanwhile, the Escherichia coli bacteria which had the most superior antibacterial activity were Co_0.9Zn_0,1Fe₂O₄ samples which were annealed at 450°C with a clear zone measuring 21.04 mm.

Abstract: Study of physico-chemical properties, adsorption and desorption of Zn using citric acid and tartaric acid on the textile industrial area has been carried out. This study aims to analyze the physico-chemical character of the soil and the content of heavy metals around the textile industry which is suspected of being contaminated by waste, the adsorption isotherm and capacity of Zn, the desorption kinetics of Zn using citric acid and tartaric acid solutions. Soil samples were divided into three sample points based on the location where they were taken, namely sample points I, II and III. The physical and chemical properties of soil were measured, included pH, ash content, electrical conductivity, total organic carbon, cation exchange capacity and content of heavy metals The adsorption capacity was studied by the adsorption of Zn on the soil. Meanwhile, the desorption was studied by using both citric and tartaric acid solution. The results showed that sample I had the highest total organic carbon content of 692.3 mg g^-1, and a cation exchange capacity of 42.0 cmol⁺ kg^-1 with a metal content of 735.0 mg kg^-1. The maximum adsorption capacity of Zn is 708.7 mg kg^-1. The optimum desorption using citric acid occurs at a concentration of 0.6 mol L^-1, pH 3 and a time of 7 h, while tartaric acid occurs at a concentration of 0.8 mol L^-1, pH 3 and a time of 7 h. Keywords: citric acid, tartaric acid, physico-chemical properties, zinc

Abstract: The use of zinc coatings deposited onto steel is one of the most important commercial processing techniques employed to protect steel components exposed to severe corrosive environments. Our objective is to improve the coated galvanizing steel used as irrigation tube in the agriculture field. After the best mechanical and chemical preparation, the substrates of this steel were galvanized by immersion in a molten zinc bath heated at 450°C during 15 min. the coated steel substrates underwent an annealing treatment in classical furnace heated at 350 °C for various holding times. This research work is to investigate the time effect of annealing treatment on intermetallic compounds of coatings obtained by hot dip galvanizing steel. For this purpose, several characterization means are used to evaluate the change effected by the annealing time on the phases of galvanizing coating. The kinetic growth of each layer relates the thickness to the annealing time by a simple power law. The treatment of annealing at temperature of 350 °C and holding time of 150 min can changed the structural and mechanical properties of coating phases. The gamma and delta layers presented the hard inner layers became relatively soft phases which would not lead to cracking and detachment of the coating.

Abstract: Copper-tin-zinc (Cu-Sn-Zn) ternary alloy coatings was successfully deposited from a less hazardous electrolyte containing copper (II) chloride, tin (II) chloride, zinc chloride, sodium hypophosphite and complexing agent. In this work, the impact of different complexing agent on morphology, chemical composition, current efficiency, microhardness, and corrosion rate were investigated by method of SEM equipped with EDX spectroscopy, weight gain measurements, XRD, Vickers microhardness test and potentiodynamic polarization measurement, respectively. It was discovered that, Cu-Sn-Zn alloys prepared using sodium formate shows the highest microhardness value. It is also can be concluded that, complexing agent have a significant impact on the appearance and the surface morphology of the Cu-Sn-Zn alloy electrodeposits.

Abstract: Corn Cob ash was used in competitive adsorption of copper, zinc, and chromium from wastewater. The central composite design; a sub-set of response surface methodology was used to optimize the adsorption of the heavy metals. The result of the statistical parameters showed the coefficient of determination (R²) of 1.000, 0.999, and 1.000 for copper, zinc, and chromium respectively. The optimal conditions obtained for adsorbent dosage, initial concentration, temperature, contact time, and particle size were 13.20 mg, 79.72 mg/l, 34.95 °C, 40.38 min, and 1400 µm, respectively with the desirability of 1.000. The predicted and the actual values of metal removal obtained were 69.41%, 76.37%, as well as 70.44%, 72.50%, 77.90 % and 71.00% for copper, zinc, and chromium respectively. The ressult indicated a good conformity between the model predicted values and the actual values, thus having small errors of 3.09%, 1.53 % and 0.56 % for copper, zinc, and chromium respectively.

Abstract: Simple and low environmental impact methods for producing chemically-stable nanoparticles of metallic zinc (Zn) are asked to be developed, because metallic Zn nanoparticles are easily oxidized in air, and organic solvents, which can be used for the fabrication of metallic Zn particles, give a great environmental impact. The present work focuses on the chemical reaction in protonic solvents containing aqueous solvents, of which the use will give a smaller environmental load, and proposes a method for producing metallic Zn nanoparticles by reduction of Zn ions in the protonic solvent. Two kinds of hydrophilic solvents were examined: water and ethylene glycol (EG). The use of water and EG as the solvents produced Zn oxide. Though the addition of aluminum salt to EG also produced Zn oxide, the crystallinity of Zn oxide was lower than that for with no addition of aluminum salt. In the case of the aluminum salt addition, nanoparticles with a size of 27. 5±13.3 nm were fabricated, and not only bonds of Zn-O-Zn and Zn-OH but also a bond of Zn-Zn were confirmed to be formed, which indicated the production of low crystallinity metallic Zn nanoparticles.