Zn In Solution Research Articles

Laser-Sintered Mg-Zn Supersaturated Solid Solution with High Corrosion Resistance.

Solid solutions of Zn as an alloy element in Mg matrixes are expected to show improved corrosion resistance due to the electrode potential being positively shifted. In this study, a supersaturated solid solution of Mg-Zn alloy was achieved using mechanical alloying (MA) combined with laser sintering. In detail, supersaturated solid solution Mg-Zn powders were firstly prepared using MA, as it was able to break through the limit of phase diagram under the action of forced mechanical impact. Then, the alloyed Mg-Zn powders were shaped into parts using laser sintering, during which the limited liquid phase and short cooling time maintained the supersaturated solid solution. The Mg-Zn alloy derived from the as-milled powders for 30 h presented enhanced corrosion potential and consequently a reduced corrosion rate of 0.54 mm/year. Cell toxicity tests confirmed that the Mg-Zn solid solution possessed good cytocompatibility for potential clinical applications. This study offers a new strategy for fabricating Mg-Zn solid solutions using laser sintering with MA.

Phytotoxicity and genotoxicity as a new approach to assess heavy metals effect on Medicago sativa L.: Role of metallo-resistant rhizobacteria

The present work deals with the phytotoxicity and the genotoxicity of three heavy metals, namely copper, lead, and zinc on Medicago sativa seeds germination. Indeed, the role of metallo-resistant bacteria in lessening heavy metal toxicity was investigated. For this purpose, solutions of Cu, Pb, and Zn were used at the rate of 0.5, 1, 1.5, 2, and 2.5 mM for 4 d, along with untreated control using distilled water. The obtained findings displayed the stronger inhibitory effect of heavy metals on the germination and rhizogenesis process as well as a significant mito-depressive effect in the meristematic cells. For instance, Cu at the rate of 2.5 mM inhibited seed germination by 95 %, root elongation fell from 2.25 (in the control) to 0.14, while the mitotic index was reduced by 155%. Moreover, inoculation with metallo-resistant bacteria attenuated heavy metal toxicity, increased germination, rhizogenesis, mitotic index, and thus plant early growth. Metallo-resistant rhizobacteria inoculation improved the germination percentage by 40 % in the case of Cu and by 24 % in the case of Zn. The overall results suggest the cytotoxicity and the genotoxicity potential of Cu, Pb, and Zn on plants even at low concentrations. Furthermore, metallo-resistant bacteria application lessened heavy metal toxicity. This study confirms the suitability of M. sativa as a plant for the phytoremediation processes.

Superabsorbents and Their Application for Heavy Metal Ion Removal in the Presence of EDDS.

Three acrylic-based superabsorbents—TerraHydrogel®Aqua (THA), Zeba®Hydrogel (ZH) and Agro®Hydrogel (AH) were used to investigate the influence of chemical conditions on kinetic and adsorption behavior towards metal ions in the presence of a chelating agent of a new generation called ethylenediamine-N,N′-disuccinic acid (EDDS). The effects of relevant parameters—mainly including those of sorbent dose, pH of the solution and initial concentration of Cu(II), Zn(II), Mn(II) and Fe(III) complexes with EDDS as well as phase contact time and temperature—on the adsorption efficiency were studied in detail by the static method. The experimental data were also characterized by kinetic and adsorption parameters obtained based on the Langmuir and Freundlich models of sorption as well as the Lagergren, Ho and McKay and Weber–Morris models.

Solid solution and precipitation strengthening effects in basal slip, extension twinning and pyramidal slip in Mg-Zn alloys

A high-throughput methodology is proposed, based on the combination of diffusion couples and advanced nanomechanical testing methods, to directly measure alloying effects on the critical resolved shear stress (CRSS) of individual deformation modes in Mg alloys. The methodology is tested in Mg-Zn alloys by assessing the alloying effects, up to Zn contents of 2 at.%, on basal slip, extension twining and pyramidal slip in two metallurgical conditions: as-quenched, for which the Zn solute atoms remain homogenously dispersed in solid solution; and peak-aged, for which the Zn atoms form rod-shape β1′ (MgZn2) precipitates. A combined approach including micromechanical testing, transmission Kikuchi diffraction, and high-resolution transmission electron microscopy was performed to reveal the corresponding deformation mechanisms. It was found that the CRSS enhancement for basal slip and extension twinning by MgZn2 precipitates is considerably larger than the effect of Zn in solid solution, while the strengthening of pyramidal slip is similar in both cases. As a result, the anisotropy ratios remain high and similar to pure Mg in the solid solution strengthened Mg-Zn alloys. However, they are substantially reduced in precipitation strengthened Mg-Zn alloys.

Of ZnO Nanoparticle using Sandoricum Koetjape Peel Extract as Bio-stabilizer under Microwave Irradiation

The use of sentul (Sandoricum koetjape) peel extract as a biostabilizer in the synthesis of zinc oxide (ZnO) nanoparticles has been carried out as an environmentally friendly production. This research was conducted by reacting a 0.2 M of Zn precursor (zinc nitrate hexahydrate) solution with Sentul peel extract (10g/l). The samples were varied based on the ratio of the volume of the Zn solution to the Sentul peel extract, i.e., 1:4, 2:3, 1:1, 3:2, and 4:1 where each sample was assigned a ZSk initial code. The ZnO synthesis used a microwave technique with a power of 360 Watt. Morphological, structural, optical absorption, and functional groups were analyzed based on the results of the characterization of SEM, XRD, UV-Vis, and FTIR Spectroscopy. SEM images show the morphology of ZnO particles in the form of semi-hollow spheres and macaron-like shapes. The particle size decreases with the addition of the volume of the Zn solution. The XRD diffraction pattern shows the diffraction peaks that correspond to the hkl plane of the wurtzite hexagonal structure of ZnO. The highest optical absorption of the UV-Vis spectrum occurred in the wavelength range of 300-360 nm. The FTIR spectrum represents the involvement of the O-H functional groups derived from the polyphenolic compound of sentul peel extract.

Removal of Cadmium, Nickel, and Zinc from aqueous solutions by activated carbon prepared from corncob - waste agricultural materials

Adsorption of zinc (Zn), cadmium (Cd), and nickel (Ni) from aqueous solutions by corncob (CC) and granular activated carbon prepared from corncob (GACC) were carried out. Synthetic solutions of Cd, Ni, and Zn at 3.0 ppm each were used to perform the adsorption process. A batch pattern was used to determine the kinetics as well as the adsorption isotherm parameters. The obtained results using either both the CC and GACC separately were found to be matched with the Langmuir isotherm model. Furthermore, the breakthrough study was conducted using GACC. The overall results indicated that the breakthrough curve for Cd, Ni, and Zn is the reverse of their adsorption, as demonstrated by R2 and kinetic constant (K) values.

Characterization of the AZ31/AW-6060 Joint Fabricated using Compound Casting with a Zn Interlayer at Relatively Low Temperature Conditions

The work deals with the fabrication of a joint between AZ31 magnesium alloy and AW-6060 aluminium alloy with the use of a Zn interlayer. The Zn layer was produced on the surface of an AW-6060 alloy insert by diffusion bonding. The insert was then placed inside a steel mould and kept at room temperature. The joint was produced using compound casting by filling the mould with liquid AZ31 alloy, heated to 650 °C. The microstructure of the bonding zone formed between joined alloys was analysed using an optical microscope and a scanning electron microscope equipped with an energy dispersive X-ray spectroscope. The properties of the joint were examined using Vickers microhardness measurements and simple shear strength testing. As a result of the experiment, the 400 μm thick bonding zone with a complex microstructure was formed between the alloys. The microstructural analysis showed that the bonding zone reveals a high concentration of Zn and Mg. The layers of a eutectoid (a MgZn phase + a solid solution of Al and Zn in Mg), a Mg5Al2Zn2 phase and a Mg(Al,Zn)2 phase with fine particles of other phases were observed there. The bonding zone was characterized by relatively high microhardness, which was related to the brittleness of the constituents. The shear strength of the examined joint was 19.6 ± 2.5 MPa.

From spent Zn–MnO2 primary batteries to rechargeable Zn–MnO2 batteries: A novel directly recycling route with high battery performance

For the first time, spent Zn–MnO2 primary batteries are recycled to directly build rechargeable Zn–MnO2 batteries with a mixed solution of sulfuric acid and hydrogen peroxide as the leachate, which aimed to the efficient recovery of spent Zn–MnO2 primary batteries and the realization of high-powered rechargeable Zn–MnO2 batteries. After simple purification, the leached liquid is directly used as the working solution to prepare an electrolytic rechargeable Zn–MnO2 battery. The experimental results show that the performance of the recycling solution of the neutral Zn–MnO2 primary battery was better than that of the alkaline Zn–MnO2 primary battery, and both performed better than the solution prepared with chemically pure reagents. After optimizing the pH of the working solution and charging current, the obtained rechargeable Zn–MnO2 battery can provide an energy efficiency of 72.33 % ± 0.55, a coulombic efficiency of 90.17 % ± 0.71, and excellent cycle stability. These experimental results show that spent Zn–MnO2 primary batteries can be successfully recycled to prepare rechargeable Zn–MnO2 batteries, demonstrating very good application potential.

Effects of the process parameters on the formation of the Zn-enriched surface layer of Mg by thermochemical treatment in a medium containing ZnCl2

The fabrication of the Zn-enriched surface layer of Mg involved annealing of the Mg specimens in a contact with the paste containing ZnCl2. Annealing of the specimen at 440 °C for 120 min resulted in the formation of a surface layer with a complex structure. In the outer zone, dendrites of a solid solution of Zn in Mg were observed at a eutectoid matrix (an MgZn intermetallic phase and a solution of Zn in Mg). The inner, transition zone, which was located at the interface adjacent to Mg substrate, was composed of a solid solution of Zn in Mg. The use of various period of annealing time (30, 60, 90 and 120 min) showed that increasing the annealing time leads to an increase in the thickness of the layer. A similar structure of the layer was observed for each variant of the annealing time. The analysis for the specimen fabricated at 410 °C for 120 min showed that the use of lower temperature resulted in a formation of a thin layer, eutectoid in structure. When higher annealing temperature (470 °C) was used, the thick surface layer with an uneven thickness and containing macroscopic unevenness was produced on the specimen surface.

Fe (III) adsorption using Fe (III) ionic imprinted polymer from polyeugenoxy acetate crosslinked with ethylene glycol dimethacrylate (EGDMA)

Ionic Imprinted Polymer (IIP) with polyeugenoxy acetate (PA) as the base polymer, EGDMA as the crosslinking agent, and AIBN as the initiator have been synthesized to adsorb Fe(III) metal ions. NIP (non-imprinted polymer) was used as a comparison for this study. The produced polymer was characterized using FTIR spectroscopy and SEM-EDX. Adsorption rate and capacity were examined through adsorption isotherm and kinetics studies for all adsorbents. The adsorption selectivity test was done with mixed-metal solutions of Zn(II), Cu(II), Cd(II), and Ag(I). The results of SEM analysis on IIP-PA show a more uniform and regular size than NIP-PA. Adsorption of Fe(III) in IIP-PA and NIP-PA follows pseudo-second-order kinetics, and the adsorption isotherm both follow the Langmuir theory. The adsorption capacity of Fe(III) metal ions in IIP-PA is 10.88 mg/g, and the adsorption capacity of NIP-PA is 7.94 mg/g. The mechanism of adsorption of Fe(III) metal ions in IIP-PA and NIP-PA was dominated by hydrogen bonds between the -COOH groups and Fe(III). In binary solutions, IIP-PA adsorption selectivity coefficient is higher than NIP-PA with the order of Fe(III)/Zn (II)>Fe(III)/Cu(II)>Fe(III)/Cd(II)>Fe(III)/Ag(I)

Structural and photoluminescence properties of zinc oxide nanorods grown on various transparent conducting oxide seed layers by chemical bath deposition

Zinc oxide (ZnO) nanorods (NRs) were grown directly on gallium doped ZnO (GZO), tin doped indium (III) oxide (ITO) and fluorine doped tin (IV) oxide (FTO) seed layers by chemical bath deposition using the mixed aqueous solutions of Zn(NO3)2•6H2O and C6H12N4 for the different growth times (tgs). Almost all of the NRs grown on the GZO seed layers, denoted by “NRs/GZO”, were vertically aligned to the substrate surface independently of tg. Some of the NRs grown on the ITO and FTO seed layers, denoted by “NRs/ITO” and “NRs/FTO”, respectively, were vertically aligned to the substrate surface and others were inclined. For both the NRs/ITO and NRs/FTO, moreover, the relative portion of the inclined NRs tended to increase with increasing tg. Both the average width (Wav) and average length (Lav) became larger in the order of the NRs/GZO, NRs/ITO and NRs/FTO, corresponding to the ascending order of the average diameter of the grains forming the seed layer. For the NRs/GZO, the Wav, Lav and density of NRs (nNRs) were almost unchanged at tg > 60 min. For the NRs/ITO and NRs/FTO, however, the increase in tg resulted in the increases in Wav and Lav and the decrease in nNRs. The opposite tg dependences between Wav and nNRs observed for the NRs/ITO and NRs/FTO indicated that the coalescence among the neighboring NRs contributed to the enhancement of Wav. For the NRs/GZO, the strains acting along thea- andc-axis directions were compressive and tensile strains, respectively. For both the NRs/ITO and NRs/FTO, however, both the strains along thea- andc-axis directions were compressive strains. All the photoluminescence (PL) spectra of the NRs exhibited a near-band-edge (NBE) emission at ~380 nm and an orange band (OB) emission at ~600 nm. Regardless of the kind of the seed layer, PL intensity ratio of the OB emission to the NBE emission (IOB/INBE) became smaller with the increase in Wav. The decrease inIOB/INBEwith increasingWavis probably due to the decrease in the volume ratio of the surface region with high concentration of interstitial oxygen atoms (Ois) to the bulk region with few Ois and the decrease in the band bending in the surface region.

Evolution of UV/VIS Photoluminescence of Aged Zn(acac)2 Solutions in Correlation with Carbon Precipitation

Photoluminescent carbon nanodots (CDs), a new class of inorganic nanocarbon materials, have become a significant segments of luminescent nanomaterials in last decade. However mechanism of light emission and detailed identification of the light emitting centers is still debated. A huge number of synthesis methods were suggested, however few of them allow to monitor formation of the CDs on the early stage and development in progress. Recently we have found that zinc acetylacetonat (Zn(acac)2) in ethanol solutions tends to be hydrolysed under room temperature laboratory conditions resulting in gradual conversion of colorless and non luminescent solution to yellowish liquid accompanied by cedimentation of nonluminescent amorphous ZnO:OH. The yellow component of the solution has been identified as dispersion of carbon precipitates. The most important is that the process of hydrolysis in very slow with changing color and PL development within several months. Such a slow process allows following the details of PL development and evolution in time correlation with carbon precipitation.Ethanol solutions of Zn(acac)2 with concentrations in range of 0.1-4.0 % were prepared and their photoluminescence was monitored for time period of several months. It has been found that early stage of carbon precipitation is resulted in development of relatively narrow PL band with maximum at about 400 nm and corresponding excitation band at 360 nm. The spectrum of the emission band is excitation independent as well as excitation band is not dependent on emission wavelength. In the course of further aging and carbon precipitation the PL band is broaden and shifted to visible range with maximum intensity in range of 420-500 nm depending on excitation wavelength. Detailed emission/excitation study revealed that the visible emission band is composed of at list two components centered at about 420-450 nm and 500 nm, with the corresponding excitation bands at 365 nm and 420 nm. Time-resolved photoluminescence spectroscopy showed that the decay of low energy emission band follows the classical mono-exponential low with the characteristic time of several nanoseconds, while the behavior of high energy component can be described by the stretched exponential low with the average decay time of several nanoseconds. PL data is summarized and discussed in the terms of subnanometer molecular-like carbon emitters and core/shell structural model of amorphous carbon nanoparticles.

Zinc - Iodine Rechargeable Flow Battery with Optimized Zn Solution for High Energy Density Devices

Nowadays, electrochemical energy storage systems have gaining interest because they constitute an essential element in the development of sustainable energy technologies [1,2]. Among them, rechargeable flow batteries (RFBs) are one of the most promising technology for the integration in grid-connected electricity, especially if combined with unpredictable and intermittent renewable energy sources, due to their high efficiency, power/energy independent sizing and room temperature operation [3]. At the moment, among all RFBs systems, the most investigated and advanced technology is the vanadium based RFB, characterized by an energy efficiency equal to 80% and energy density ranging 15-45 Wh/l [4]. However, currently the main bulk of research is focused on finding an economically convenient and technically competitive flow battery chemistry, able to ensure long lifetime and high energy efficiency [5,6]. In this study, a zinc-iodine RFB with low cost and high energy density will be presented. In particular, inorganic electrolytes based on high soluble salts have been developed to increase the charge density of the device. Moreover, a deep study on the effects of organic additive for the proper zinc developed electrolyte, aiming to reduce the dendrites growth and to increase the current efficiency, have been analyzed. In order to investigate the effect of these chemical compounds, the developed solutions have been characterized by means of cyclic voltammetries while the obtained zinc metallic coatings have been morphological characterized using scanning electron microscopy. The combination of high energy efficiency of the Zn-I RFB, in the order of 70% at 20 mA cm-2, with its very high energy density ranging from 25 to 60 Wh/l, depending on the formulation of the electrolytes, its ability to withstand a large number of charge/discharge cycles and the low cost, makes this battery system suitable for large energy storage applications. References P. Alotto, M. Guarnieri, and F. Moro. Renewable and Sustainable Energy Reviews 29 (2014): 325-335.A. Z. Weber, M.M. Mench,, J.P. Meyers, P.N. Ross, J.T. Gostick and Q. Liu. Journal of Applied Electrochemistry (2011), 41(10), 1137.G. Kear, A.A Shah, and F.C. Walsh. International journal of energy research, (2012), 36(11), 1105-1120.C. Ding, H. Zhang, X. Li, T. Liu, and F. Xing. The Journal of Physical Chemistry Letters, (2013), 4(8), 1281-1294.C- Xie, Y. Duan, W. Xu, H. Zhang, and X Li. Angewandte Chemie International Edition, (2017) 56(47), 14953-14957.S. Selverston, R. F. Savinell, and J. S. Wainright. Journal of The Electrochemical Society 164.6 (2017): A1069-A1075.

Study of Zwitterionic Homopolymer Polysulfobetaine and Gel Properties in Various Solutions of Different Anion Species and Cation Valences

Z witterionic homopolymer polysulfobetaine (PBET) gels were synthesized using free radical polymerization. The effect of temperatures on adsorption behavior of the gel and transition temperature of the polymer in various solutions of LiCl, KCl, NaCl, Al(NO 3 ) 3 , Zn(NO 3 ) 2 , and NaNO 3 were studied. The tendency of poly(BET)s transition temperature in Cl solutions very identical. All of poly(BET) solution resulted in Upper Critical Temperature (UCST). Its number increased along with the elevation of salt concentration. The number declined again when the concentration was too high. BET gel successfully adsorbed various ions with the amount of adsorption tendency of LiCl < NaCl < KCl.

Evolution of UV/VIS Photoluminescence of Aged Zn(acac)2 Solutions in Correlation with Carbon Precipitation

Evolution of photoluminescence of ethanol solutions of Zn(acac) from near UV to VIS was monitored for time period of several months. It has been found that transparent solutions with time colored in light brown that is accompanied by development of strong visible photoluminescence. This phenomenon is analyzed and discussed in terms of carbon precipitation. It has been demonstrated that at short aging period the photoluminescence is observed as relatively narrow and excitation independent emission band centered at at about 400 nm. In course of aging period emission is converted from violet to blue and green with corresponding shift of excitation band from UV to VIS. Electron paramagnetic resonance spectroscopy allows to identify carbon precipitates in the solutions approving hypothesis on nanocarbon nature of the photoluminescence.

Role of Zn and Mg substitutions on the mechanical behaviour of biomimetic hydroxyapatite and insight of the emergence of hydroxyapatite-ZnO nanocomposite

A simple and inexpensive biomimetic method is attempted to produce hydroxyapatite (HAp), Mg-/Zn-doped HAp and HAp-ZnO nanocomposite. An aqueous calcium solution with and without precursors of Mg2+ or Zn2+ and a carbonate containing phosphate solution are prepared at a temperature of 37 °C with pH of 7.4 and mixed in equal volumes to obtain the calcifying solution, which has similar ionic constituents as that of human blood plasma. At a temperature of 37 °C, reactions drive the calcifying solution to supersaturation for the crystallization of carbonated HAp, Mg-/Zn-doped HAp, and HAp-ZnO nanocomposite. The microstructural and morphological analyses reveal that the carbonated HAp can sustain low doping of Mg and Zn substituting at Ca sites, wherein Zn is likely to replace screw axis Ca preferentially. Significant lattice distortion leads to the transformation of nanophase HAp to amorphous calcium phosphate when Mg content in the calcium solution is increased to 40% of (Ca + Mg) solute concentration. The role of Zn is more intriguing – Ca-vacancy mediated substitution is favourable when Zn content is below 15% of (Ca + Zn) solute concentration and subsequent increase leads to the emergence of spherical ZnO nanocrystals coexisting with needle-like HAp nanocrystals. The present work describes a new way of synthesizing HAp-ZnO nanocomposite – a potential candidate for the orthopaedic and the prosthodontic applications. Simply increasing Zn content in the calcium solution and without using additional precursors, reaction pathways lead to the precipitation of HAp-ZnO nanocomposite. Field emission transmission electron microscopy reveals that when Zn/(Ca + Zn) molar ratio in the calcifying solution is set at 40%, the resulting nanocomposite is characterized by 5 nm average diameter needle shaped HAp with 15–30 nm spherical ZnO particles as an intimate mixture of two nanophase systems. The mechanical properties of HAp evaluated using the X-ray elastic constants and the modified Williamson-Hall analyses suggest a clear decreasing trend of the apparent domain size with increasing Mg and Zn incorporations while microstrain, isotropic stress, and uniform deformation energy density of nanophase HAp rise only with increasing Mg substitutions.

Stacking-fault mediated plasticity and strengthening in lean, rare-earth free magnesium alloys

A magnesium alloy with lean additions of Zn (1 wt.%) and Ca (0.3 wt.%), ZX10, and pure Mg were subjected to orientation-dependent micropillar indentation tests at ambient temperature. Single-crystalline micropillars of two different orientations were fabricated to activate extension and compression along the c-axis, respectively. For both loading conditions, ZX10 exhibits a strengthening increment by a factor of 2 to 2.5 compared to pure Mg along with plasticity enhancement. Correlative transmission electron back-scattered diffraction and transmission electron microscopy reveal that deformation in ZX10 proceeds by deformation twinning under c-axis extension, generating homogeneous activation of basal and non-basal slip at higher strains. In contrast, pure Mg displays deformation through tension twinning and basal slip. Pure Mg under c-axis compression deforms by basal dislocation-mediated massive sliding, while ZX10 reveals dual activation of basal 〈a〉 and pyramidal 〈c+a〉 dislocations. Mechanistically, the minute additions of Zn and Ca solutes modify the intrinsic stacking-fault energy, which accounts for the simultaneous strengthening and ductility enhancement. These findings highlight the beneficial impact of dilute additions of Zn and Ca in activating novel deformation pathways that are critical for designing rare-earth (RE) free high-strength, highly ductile magnesium alloys for structural and biomedical applications.

Laboratory Adsorption Studies on Ni(II) and Zn(II) Solutions by Sugarcane-Bagasse Ash

Large volumes of sugarcane-bagasse ash are produced as residues from the sucro-alcohol industry and have some practical applications. The use of this ash as an adsorbent for the removal of Ni(II) and Zn(II) is studied in the present paper. Effects of pH, adsorbent concentration and equilibrium time have been studied in order to establish the best conditions for the removal of metal ions. The kinetic parameters, i.e. the constant rate, equilibrium sorption capacity and related coefficients of each kinetic model (pseudo-first order, pseudo-second order and Elovich), have been evaluated by means of nonlinear regression fit: the pseudo-second order best describes the kinetics of the process. The experimental data obtained from the equilibrium study were analysed using nonlinear Freundlich, Langmuir, Temkin and Toth models: the Langmuir and Toth isotherms best represent the sorption of the metal ions. The highest experimental sorption capacities obtained as regards the removal of Ni(II) and Zn(II) from the sugarcane-bagasse ash were 0.0298 and 0.0416 mmol g−1, respectively. The adsorption mechanism through the formation of covalent bonds and hydrogen bonds demonstrates the affinity between the adsorbent and the adsorbates. The studies were conducted separately, using independent solutions of each metal.

Modelling the thermodynamic data for hcp Zn and Cu–Zn alloys– an ab initio and calphad approach

The phase diagrams of systems between zinc and elements such as Cu, Ag and Au show two distinct hcp phases on the Zn side of the system. Because of this, it is difficult to model the thermodynamic properties of these phases within a single dataset. As a result it is common to assess the data for these systems with two hexagonal phases, a phase HCP_A3 with a near ideal c/a ratio and the terminal solid solution of Zn with an anomalously high value for this ratio designated as HCP_ZN. We have examined the effect of additions of Cu on the enthalpy of mixing and lattice parameters of HCP_ZN in order to verify, using ab initio calculations, the origin of the above mentioned thermodynamic model for the alloy. The analysis of the calculations allows us to suggest a possible alternative to the state-of-the-art two hcp phases approach akin to the magnetic model used with success within the CALPHAD modelling.

Antimicrobial composites of nanoparticles generated by gamma irradiation supported in clinoptilolite-rich tuff

In developing countries, rates of hydric illness in children are high because of the consumption of non-potable water. Therefore, it is important to investigate new methodologies to diminish microorganisms’ concentration in the water that is used in rural areas for drinking. Microbicide agents with a base of natural zeolites can be an alternative to water disinfection instead of using other kinds of disinfectants that produce by-products. Hence, the synthesis and characterization of metallic or oxide-metallic nanoparticles-natural zeolite composites to evaluate the antimicrobial activity in front of Salmonella typhimurium and Candida albicans in this work were investigated. The natural zeolite was in contact with salt solutions of Ag, Cu, or Zn to obtain the modified natural zeolites, and they were then gamma irradiated to generate the nanoparticles. The samples were characterized by different techniques. The Salmonella typhimurium and Candida albicans were suspended in distilled water and put in contact with the composites at different times. The kinetic of the cellular decay was obtained using the Chick model. The chemical species of the nanoparticles obtained were Ag, Cu2O, and ZnO. The kinetic parameter of the cell decay of both Salmonella typhimurium and Candida albicans is the biggest for silver nanoparticles-natural zeolite composite (Z-NpsAgγ). Between two independent experiments of the cellular decay, differences in the k values were observed. The antimicrobial activity of these composites depends on the characteristics of each microorganism, the mass of the composite, the content of the metallic or oxido-metallic nanoparticles in the natural zeolites, their distribution on the zeolitic material surfaces, and the chemical species obtained during the gamma irradiation. The Z-NpsAgγ could be an alternative for water potabilization.