Concentration Of Zn2 Research Articles

ZnO Electrodeposition on Boron-Doped Diamond: Effects of Zinc Precursor Concentration

ZnO is a wide band gap (3.32 eV) semiconductor with n-type conductivity, which is used in many devices for different applications, including gas sensors, transparent electrodes, and acousto- and electro-optical devices. Recently, the combination of ZnO with boron-doped-diamond (BDD) was used in order to make heterojunctions [1], surface acoustic-wave (SAW) devices [2] and biosensors electrodes [3]. On the majority of presents works, ZnO was deposited on BDD by chemical vapor deposition (CVD) [4], magnetron sputtering [5] or atomic layer deposition (ALD) [6]. The electrodeposition represents an interesting new way for the deposition of ZnO on BDD. The electrodeposition of ZnO has been successfully performed on many conductive substrates [7] but only one time on BDD [8]. This chemical route presents a few advantages such as low cost and possibility to obtain a large range of structures from the dense layer up to well-defined nanostructures. The electrodeposition of a metal oxide such as ZnO consists to a redox process at the electrode surface, to raise the local pH and then to precipitate an oxide or hydroxide phase. Three different precursors can be used to produce hydroxide at electrode surface: hydrogen peroxide, nitrite salt or dissolved oxygen. This last one is used in our work. Dissolved oxygen is reduced, raising the local pH on the conductive diamond electrode and causing the precipitation of zinc hydroxide [9]. Then the dehydration of hydroxide leads to zinc oxide according to the following scheme. O2 + 2 H2O + 4 e- -> 4 OH- (1) Zn2+ + 2 OH- -> Zn(OH)2 (2) Zn(OH)2 -> ZnO + H2O (3) In this work, zinc chloride (ZnCl2) as precursor is used for the first time on BDD and potassium chloride (KCl) as support electrolyte. Our aim was to study the influence of deposition parameters such as zinc precursor concentration, substrate’s surface chemistry or bath temperature, on ZnO morphologies. The resulting ZnO deposits were characterized using X-ray Diffraction (XRD) and scanning electron microscope (SEM). The effect of [Zn2+] is illustrated on figures 1 and 2. As evidencing by XRD (Fig. 1), deposits obtained at 60°C, on as-grown BDD substrate, with 1 mM and 5 mM of Zn2+ correspond to well-crystallized zinc oxide. In both cases, the intensity of diffraction peak (002) indicates a preferential growth to the c-axis. The diffraction peaks from the substrate are labeled with an asterisk. SEM images (fig. 2) confirm the preferential orientation along c-axis. However, ZnO morphologies are completely different by changing Zn2+ concentration. Indeed, with a concentration of 5 mM, micrometric hexagonal grains are obtained while with a concentration ≤1 mM, nanometric pyramids are grown. Finally, our work shows that electrodeposition of ZnO is fully applicable on diamond substrate. And, parameters such as concentration of Zn2+, BDD’s surface chemistry or bath temperature, allow modifying the morphology of deposits.

Effects of Zinc on the Growth of Several Vegetables

Heavy metal zinc is one of the trace elements necessary to the growth of vegetable, but Zn excessiveness also could cause damage. In this research, four vegetables were planted by soil culture method under different Zn2+concentration controlled by the exogenous Zn2+addition; their growth characteristics were analyzed to find the sensitive growth indexes to Zn and compare their tolerance to Zn pollution. Results show that: low concentration of Zn2+(< 100 mg/kg) can promote significantly the plant height and the root length growth of all the four vegetables, while, as the exogenous Zn2+increased to the concentration of 150 mg/ kg, the number of leaves, the above-ground dry biomass and the underground dry biomass were suppressed significantly; in this experiment, the four vegetables appeared different sensitivity to Zn stress,Lactucasativavar.longifoliafappeared highest tolerance andBrassicachinensisappeared less sensitivity to Zn stress.

3-py-TTF: Efficient and Simple Colorimetric Sensor for Copper Ion in Aqueous Solutions

Compound 1 shows remarkable sensing and coordinating properties only to Zn2+ ion, not to the other metal ions. Addition of a micromolar concentration of Zn2+ ion to the solution of 1, a dramatic change is observed in the UV–vis absorption spectrum and redox property, and the discrimination is readily possible even by “the naked eye.” Comparison of the recognition ability between 1 and its reference compound 2 suggests that the nature of the space linking tetrathiafulvalene and acceptor moiety plays an important role in the intramolecular charge-transfer state.

Removal of Zinc Ions from Aqueous Solutions by Micro-Electrolysis and Iron Hydroxide Self-Flocculation

This study was performed to determine the feasibility of enhancing removal of zinc ions from aqueous solutions using an iron-carbon internal micro-electrolysis (ICIME) followed by iron hydroxide self-flocculation (IHSF) process. Results shown that the Zn2+ removal using ICIME was improved by IHSF significantly. The pH=3, mass ratio of Fe/AC=2: 1, hydraulic reaction time=30min of ICIME and pH=9, both aeration time and static placing time were 60min of IHSF were proposed as the optimum conditions. Under these conditions, the removal efficiency and residual concentration of Zn2+ from lead and zinc smelting wastewater were reached 99.10%, 1.32mg/L. Meanwhile, other metal ions and the F- also were removed effectively. Lead and zinc smelting wastewater could meet the discharging standard (integrated wastewater discharge standard (GB8978-1996)) of China. The Zn2+ removal was significantly influenced by other metal ions existing in aqueous solutions. Contrast and breakthrough time experiment indicated the Compare with single Fe and ICIME, ICIME followed by IHSF have a higher efficiency and bearing capacity for Zn2+ removal. ICIME removal of Zn2+ enhanced by IHSF is a feasible method.

Potential foliar fertilizers with copper and zinc dual micronutrients in nanocrystal suspension

Control preparation, aqueous stability, and ion release of several Cu–Zn-containing crystals in suspensions have been investigated as potential dual micronutrient foliar fertilizers. These crystals were prepared by quick co-precipitation through simultaneously adding potassium hydroxide and copper salt solutions into zinc salt solution, and characterized in structure and composition with XRD, FTIR, SEM, TEM, and ICP in detail. As-prepared Cu–Zn mixed hydroxide nitrate was identified as a two-phase mixture while Cu–Zn mixed hydroxide sulfate as a single-phase compound. These crystals are all sheet-like in morphology and stable in aqueous solutions with pH 5–9. No phase change was detected after the samples were kept in shelf for >3 months, suggesting that these crystals have long shelf lives. In terms of ion release, Cu–Zn mixed hydroxide nitrate and Cu–Zn mixed hydroxide sulfate can afford ~4 and ~1 mg L−1 of Cu2+, respectively, which could be suitable for different levels of copper deficiency in plants. Moreover, both compounds can provide 38–39 mg L−1 of Zn2+ in aqueous suspensions. Thus, our findings suggest that as-prepared compounds can be potentially applied as long-term foliar fertilizers to simultaneously correct deficiencies of copper and zinc in various crops. Cu–Zn dual micronutrient foliar fertilizer crystals provide a certain concentration of Zn2+ and Cu2+ for foliar uptake by the plant to correct the element deficiency.

Zn2+ doped ormosil–phosphotungstate hybrid films with enhanced photochromic response

Owing to the wide use of photochromic materials in UV sensors and dosimeters, considerable efforts have been made to increase the UV-response and sensitivity of the existing classes of photochromic materials. In this study, we report a simple sol–gel route for the preparation of highly photochromic transparent films based on ormosil–phosphotungstate hybrid materials. The effect of addition of Zn2+ ions on the photochromic response of these hybrid films and the possible mechanism involved is discussed. Compared to the undoped samples, the photochromic response of the Zn2+-doped hybrid films increases by 59–237 % depending on the concentration of Zn2+ ions added to the sol formulation. No structural or electronic change in the phosphotungstate dye was observed by vibrational spectroscopy or UV spectroscopy, though micro X-ray fluorescence (μ-XRF) analysis showed that the addition of Zn2+ in the sol–gel preparations leads to an increase in the amount of phosphotungstate (HPW) incorporated in the dip-coated films. Furthermore, TEM and nano-energy-dispersive X-ray showed formation of nano-agglomerates consisting of Zn and HPW in the Zn2+-doped samples. Zn K-edge X-ray absorption near edge structure analysis also confirmed the formation of the salt Hx[Zn(OH2)6] 2−xPW12O40. It is suggested that these Zn-phosphotungstate nano-agglomerates get trapped into the ormosil network during films preparation leading to increased concentration of the phosphotungstate anions in the films, in accordance with results from μ-XRF analysis. Raman spectroscopy confirmed that the Keggin structure of HPW is preserved in the hybrid films. FTIR spectra of the matrix part of the samples are identical before and after UV-irradiation, which suggests that the photochromic process does not involve oxidation of the organic functionalities. These highly photochromic hybrid films are promising candidates for the design of practical UV-sensing devices and dosimeters.

Effect of Zn2+ on the Performances and Methanogenic Community Shifts of UASB Reactor During the Treatment of Swine Wastewater

Zn2+ was added to one of the two identical bench-scale upflow anaerobic sludge blanket (UASB) reactors in steady-state period treating swine wastewater to evaluate the effects of Zn2+ on performance and methanogenic population. Real-time quantitative PCR (QPCR) was used to quantify the 16S rRNA gene concentrations of the four methanogenic orders. In both reactors, the hydraulic retention time (HRT) was sustained at 48 h and the inner temperature was kept at 35 °C. Both promotion and inhibition of Zn2+ on chemical oxygen demand (COD) removal, methane production and methanogens community were observed in accordance with different Zn2+ dosages. COD removal rate and methane production reacted in the same way as methanogens, suggesting that the impact of Zn2+ on the methanogenic community was the critical reason that caused the changes of UASB performance in treating swine wastewater with unstable Zn2+ concentration. Among the methanogenic community, Methanomicrobiales (MMB) was the dominant group which got visibly impacted by the dosed Zn2+. Overall, lower concentration of Zn2+, e.g., less than 17.8 mg/L, was supposed to be advisable for a stable and high efficient treatment of swine wastewater by UASB reactor in practice.

Soil factors affecting solubility and mobility of zinc in contaminated soils

In view of modern worldwide research carried out in the context of broadly understood soil chemistry and monitoring of the natural environment, the methods of assessing the risk of Zn contamination in soil and agricultural crops based on the analyses of Zn concentration in the soil solution have gained more recognition. Accordingly, research on the evaluation of the effects of selected soil properties on changes in solid/solution partitioning coefficient (K d), the total concentration and activity of zinc in the soil solution was undertaken in this study. The study was based on the microplot field experiment. Investigated soil factors were as follows: soil texture, pH, organic carbon content and the degree of Zn contamination. The results indicated that zinc activity in the soil solutions was very high and comparable to the total concentration of zinc. The investigated soil properties significantly influenced the K d, the total concentration of zinc, as well as the concentration of Zn2+ in the soil solution. The total concentration and activity of zinc in the soil solution increased with increasing Zn content in the soil and rising soil acidity, while they decreased with increasing the content of organic carbon and clay particles. The values of K d increased significantly with rising soil pH and total Zn content and decreased with increasing soil organic content. Observed K d values were significantly higher in soil with 13 % clay than in soil with 7 % clay.

Polymer-based biocompatible fluorescent sensor for nano-molar detection of Zn2+ in aqueous medium and biological samples

Chemosensors are prepared through condensation reactions between polymeric amines and three different aldehydes; the activities of the three products were evaluated in DMF–H2O (7 : 3, v/v) solvent system. Chemosensor 2c demonstrated selectivity for Zn2+ enhancement of the fluorescence intensity at 420 nm. Upon binding of 2c with Zn2+, an approximately 9 fold enhancement in fluorescence intensity was observed due to the combined effect of ESIPT, CN isomerisation and the two-channel quenching of PET. The investigation of the photophysical properties of 2c revealed that the sensor at low pH led to a shift in the emission profile because of the presence of two types of nitrogen i.e. sp2 and sp3 nitrogens and the pH dependent fluorescence profile is due to the protonation at sp3 hybridised nitrogen that influences the charge transfer transitions of 2c. However, the salt effect has not much influence on the photophysical properties of 2c; and 2c was found to form organic nano-particles (ONP) in a DMF–H2O (1 : 99, v/v) solvent system and this material was found to detect a minimum of 40 nM concentration of Zn2+. The receptor 2c was found to be biocompatible through MTT assay and potent to detect Zn2+ in real biological conditions of microbial cells. The compounds 2a, 2b and 2c while immobilized in PVC based membrane, exhibited their selectivity for zinc ions as ion selective electrodes. These electrodes responded linearly in a wide concentration range with a lower detection limit of 10 μM. The electrodes have been successfully used as indicator electrodes in potentiometric titration of zinc ions with EDTA.

Fabrication of porous microspheres and network arrays of Zn–Al hydrotalcite-like compounds on Al substrate via facile hydrothermal method

The porous microspheres and network arrays of Zn–Al hydrotalcite-like compounds were synthesized on Al substrate using sodium oxalate via a facile one-step hydrothermal approach at low temperature (70°C). The Zn–Al hydrotalcite-like microspheres assembled by numerous interlaced curved nanoplates with thickness of about 50nm were generated when the concentration of sodium oxalate is 0.21M. The XRD pattern indicates that the product was of good quality in terms of phase purity and crystallinity. The morphology of Zn–Al hydrotalcite-like compounds and the thickness of nanoplates varied with the concentration of sodium oxalate, which should be attributed to the different nucleation density and growth rate. When the concentration of Zn2+ and sodium oxalate was proportionally reduced the low nucleation density and growth caused the formation of porous network arrays. The reaction temperature directly affected the diffusion rates of ions and thus the density of the nucleation and growth is responsible for the morphology change when the reaction temperature is varied. Additionally, the Zn–Al hydrotalcite-like microspheres transformed into porous network arrays when the sodium oxalate was substituted by the equivalent sodium acetate, which should be attributed to the low alkalinity of sodium acetate. The density and thickness of nanoplates composed of the porous network arrays can be effectively tailored by adjusting the concentration of sodium acetate. On the basis of experimental results, the growth mechanism was proposed and discussed.

The Effects of Nano-SiO<sub>2</sub> and Nano-ZnO on the Concentration of Chlorophyll-a in Seawater

Effects of nano-SiO2 and nano-ZnO on the concentration of chlorophyll-a in seawater were studied. Different particle size of nano-SiO2 and nano-ZnO (10~500nm) were added into seawater with different content ranging between 5~100mg/L, led to the v (growth rate) of chlorophyll-a were -11.4~-44.8% and -39.6~-74.0% respectively, and v decreased with the increasing of the concentration of nanoparticles and raised with the increasing of the nanoparticles size, and nano-ZnO had the stronger inhibitory effect than nano-SiO2. While to nano-ZnO and Zn2+(concentrations of zinc were 0.05~1.00mmol/L), chlorophyll-a growth rate decreased as the concentration of zinc increased and the average growth rates were -60.2～-68.8%, meant that nano-ZnO and Zn2+ have the same toxical mechanism. Concentrations of Zn2+ released from nano-ZnO (30nm and 90nm) with content of 5~100mg/L were 1.56~4.29mg/L, and rose with the increasing of nano-ZnO concentration, and 30nmZnO released more Zn2+ than 90nm. To nano-ZnO, percentage of the concentration of Zn2+ released by it and its v values have linear correlation, indicated that the released Zn2+ is the main reason for toxicity of nano-ZnO.

Zn/Zn(II) Redox Kinetics and Zn Deposit Morphology in Water Added Ionic Liquids with Bis(trifluoromethanesulfonyl)imide Anions

The use of room temperature ionic liquids (RTILs) as potential electrolytes for rechargeable Zn-anode batteries suffers from a disadvantage of insufficient conductivity. In this study, water added ionic liquids composed of pyrrolidinium/imidazolium cations and bis(trifluoromethanesulfonyl)imide anions were investigated with regard to their physicochemical behavior and their response to Zn/Zn(II) redox reactions. Peak conductivity was achieved by adding water within the range of 2.0–2.5 wt%. The best kinetic properties for Zn/Zn(II) redox, including decreased redox overpotential and on average three times the diffusion rate and exchange current density, were also achieved for this composition range. Density functional theory (DFT) calculations showed that water addition led to the weakening of Zn-TFSI bonds and, consequently, an increase in the concentration of Zn2+ dissolved in RTILs and involved in the redox reaction, which accounts for the improved Zn redox kinetics. Water also affected the morphology of Zn electrodeposited from RTILs. Zinc deposits grew from nanocrystalline to microcrystalline in scale with poorer adhesion in water added RTILs with pyrrolidinium cations. However, Zn deposits obtained from water added RTILs with imidazolium cations showed no obvious change in size and adhesion properties.

Growth of ZnO Nanosturctures on Porous Silicon in Different Concentration of Zn2+ Ion

In this work, zinc nitrate was used as starting materials while hexamethylenetetramine as stabilizier and deionized water as a solvent. Electrochemical etching method was employed to modify p-type silicon wafer surface in substrate preparation. ZnO nanostructures were simply deposited on substrate by sol-gel immersion method. Different molarities of precursor were prepared to study the effect of Zn2+ ion concentration in growth of ZnO nanostructures. Field Emission Scanning Electron Microscopic (FESEM) revealed that concentration of Zn2+ ion precursor influences the growth of ZnO nanostructures. ZnO nanoflower was formed in low molarity and becomes nanospherical composed by nanorods in high molarity. X-Ray diffraction (XRD) spectroscopy was employed to analyse the structural properties. The result was confirming the formation of hexagonal wurtzite of ZnO nanostructures. Besides, the growth of ZnO nanostructures was aligned to (002) towards higher molarity.

Readily dispersible clay and its role in the mobility of transition metals Cd2+, Cu2+ and Zn2+ in an alkaline alluvial soil

Readily dispersible clay is the part of the clay fraction in soils that potentially disperses in water when a small amount of mechanical energy is applied to soil. Column and batch experiments were conducted to identify the effect of readily dispersible clay on the mobility of some metal ions in a disturbed soil sample. The clay fraction (<0.002 mm) was separated from an alkaline Vertisol from the Nile River Delta. X-ray diffraction technique was used to identify minerals present in the clay fraction. Clay suspensions and deionized H2O solutions of Cd2+, Cu2+, and Zn2+ were prepared and used as influents in soil columns. Adsorption capability of the studied soil among the three metal ions was investigated. The results showed high adsorption capacity of Cd2+, Cu2+, but not Zn2+ for the studied soil. Cu2+ was the highest adsorbed metal by soil and its sorption increased at small equilibrium concentrations compared with Cd2+ and Zn2+. For the three studied metal ions, Langmuir model represented the best fit to the adsorption data. The concentration of Zn2+ and Cd2+ in leachates increased as the leaching solution volume increased, while Cu2+ showed a homogeneous distribution throughout the soil column. According to DTPA extractable metals, Zn2+ was appeared at greater depths than Cd2+, while Cu2+ had homogeneous distribution through the soil column.

Effect of surface modification of zinc oxide on the electrochemical performances of [Ni4Al(OH)10]OH electrode

Surface modification of zinc oxide on the [Ni4Al(OH)10]OH has been performed by a chemical surface precipitation method. Inductively coupled plasma measurements show that the amount of ZnO of prepared samples increases with the increase of initial concentration of Zn2+ in the mother solution. Powder X-ray diffraction measurements and scanning electron microscope images show that the modification of ZnO has little effects on the lattice parameters and the particle sizes of the [Ni4Al(OH)10]OH, but does change the morphology. The charge–discharge cycles results show that the deterioration rate of discharge capacity for the electrode with ZnO is only 4.0 % after 255 cycles, which is lower than that of electrode without ZnO (8.5 %); meanwhile, the maximal numbers of exchanged electrons per nickel atom for the electrodes with ZnO are basically over 1.83, which are higher than that of the electrode without ZnO (1.73), indicating that the modification of ZnO can improve the utilization of active material. In addition, the cyclic voltammogram tests results show that the modification of ZnO not only improves electrochemical cyclic reversibility but also elevates the oxygen evolution potential. Electrochemical impedance spectroscopy measurements show that the modification of ZnO can lower the double layer capacitance and the charge transfer resistance.

Deployment of microbial sensors to assess zinc bioavailability and toxicity in soils

Zinc (Zn) is a metal ubiquitous in the environment and essential to biological systems. Elevated concentrations of Zn in soil, however, can pose a threat to biota. This study measured bioavailability and toxicity of Zn in soil using the luminescence marked constitutively expressed Escherichia coli HB101 (pUCD607) and the Zn specific E. coli MG1655 (pZNT-lux) sensors. Four soils, representing a range of physico-chemical properties, were amended with known amounts of Zn doses and subsequently conditioned to remove artefacts of metal amendment. Field soils contaminated by Zn from galvanised electricity pylons were collected. In all soils, free Zn2+, total dissolved and exchangeable Zn were operationally defined using standard techniques. Bioavailability and toxicity of Zn was assessed in soil solutions, soil water extracts and corresponding slurries. In soil solutions, the biological responses of both of the bacterial biosensors correlated significantly with the concentration of Zn2+. In comparison to soil water extracts, soil slurries in which the sensors were exposed both to the aqueous and solid associated Zn, resulted in enhanced Zn toxicity and higher bioavailability. This enhanced Zn dosing has come from the mobilisation of exchangeable Zn from the soil sorption sites displaced by the added bacterial sensors and the associated buffer. The extent of mobilisation of exchangeable Zn and its subsequent bioavailability was governed by intrinsic soil properties. Soil slurry assays may offer a new angle in interpreting biosensor responses in soils but this must be seen both in the context of the soil aqueous response and after collating relevant chemical data about the metal of interest.

Chronic toxicity of zinc sulphate in Procambarus clarkii

We evaluated the chronic toxicity of zinc sulphate in the crayfish Procambarus clarkii.Mature P.clarkii were exposed to 0,0.40,4.04,or 40.37 mg/L Zn2+ for 21 days.Each day,we randomly selected five crayfish in each group and collected samples of the hepatopancreas,gill,and muscle tissue from males and females and ovar-ian tissue from each female.The tissues were placed in Bouin's fixative for 24 h,sectioned in paraffin,and stained using H?E.We observed a number of brick red particles in the cytoplasm of cells from the hepatopancreas and antennal gland in animals exposed to Zn2+.The number of these particles was positively correlated with the con-centration of Zn2+ and exposure time.There was no obvious histopathology in the group exposed to 0.40 mg/L Zn2+.We observed bleeding and necrosis in hepatopancreas,antennal gland,and gills in the group exposed to 4.04 mg/L after 7 d.The proportion of necrotic cells increased as the concentration of Zn2+ and time of exposure in-creased.We observed spermatocyte necrosis after 14 d in exposure to 40.37 mg/L Zn2+.After 21 d,we observed bleeding of the spermary and ovary and necrosis of the ootid and spermatocyte cells.A large number of hepato-cytes exhibited necrosis and had dropped from the hepatic ducts.The connective tissue exhibited hyperplasia,with large numbers of cells blocking the hepatic ducts,resulting in macroscopical bulky grains in the hapatopancreas of the group exposed to 40.37 mg/L.Our results suggest that exposure to 4.04 mg/L Zn2+ for 21 d causes pathological changes in the hepatopancreas,antennal gland,gills,and gonad tissue of P.clarkii.Given that zinc sulphate inter-feres with the metabolic,respiratory,and reproductive systems,chronic exposure is likely to threaten the survival of P.clarkii populations.

The Effects of Trace Elements on the Lipid Productivity and Fatty Acid Composition ofNannochloropis oculata

The effects of trace elements on the lipid productivity and fatty acid composition ofNannochloropis oculata (N. oculata)were studied. The results showed that trace elements had a strong influence on not only the lipid productivity but also the fatty acid composition. The addition of Fe3+, Zn2+, Mn2+, Mo6+, and EDTA and the deletion of Cu2+and Co2+can increase the lipid productivity. The optimum concentrations of the trace elements in the culture medium are 6 times of Fe3+and EDTA, the same concentration of Zn2+, Mn2+, and Mo6+as the control group, but the optimum medium has no Cu2+or Co2+. Fe3+, Zn2+, Mn2+, Mo6+, and EDTA are indispensable during the EPA formation ofN. oculata. The addition of Fe3+, Zn2+, Mn2+, Mo6+, and EDTA can strongly increase the content of EPA in the lipid ofN. oculata, but the concentration of the trace elements had little influence on the level of EPA.

Effect of the lattice ions on the calcite flotation in presence of Zn(II)

The effect of Zn2+ on calcite flotation and the effect of lattice ions on calcite flotation in presence of Zn2+ were investigated through microflotation tests, zeta potential measurements, and surface analysis. The results show that Zn species inhibit the interaction between the reagents and calcite through the formation of surface precipitation coating on the calcite surface, when the concentration of Zn2+ is higher than 10−5mol/L. The effect of Zn species on calcite flotation can be decreased with the increase of Ca2+, instead of CO32-. In presence of Ca2+ and CO32-, the change of floatability suggests that Zn species can be desorbed with an optimum ratio of Ca2+/CO32-. The zeta potential measurements and surface analysis show the existence of a mixture of hydrozincite and zinc hydroxide products on mineral surface, and zinc surface coating can be desorbed due to the strong chemical adsorption of Ca2+ and the formation of hydrozincite in the bulk solution.

Cytotoxic effects of ZnO hierarchical architectures on RSC96 Schwann cells

The alteration in intracellular Zn2+ homeostasis is attributed to the generation of intracellular reactive oxygen species, which subsequently results in oxidative damage of organelles and cell apoptosis. In this work, the neurotoxic effects of ZnO hierarchical architectures (nanoparticles and microspheres, the prism-like and flower-like structures) were evaluated through the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay using RSC96 Schwann cells as the model. Cell apoptosis and cell cycle were detected using flow cytometry. The concentration of Zn2+ in the culture media was monitored using atomic absorption spectrometry. The results show that ZnO nanoparticles and microspheres displayed significant cytotoxic effects on RSC96 Schwann cells in dose- and time-dependent manners, whereas no or low cytotoxic effect was observed when the cells were treated with the prism-like and flower-like ZnO. A remarkable cell apoptosis and G2/M cell cycle arrest were observed when RSC96 Schwann cells were exposed to ZnO nanoparticles and microspheres at a dose of 80 μg/mL for 12 h. The time-dependent increase of Zn2+ concentration in the culture media suggests that the cytotoxic effects were associated with the decomposition of ZnO hierarchical architecture and the subsequent release of Zn2+. These results provide new insights into the cytotoxic effects of complex ZnO architectures, which could be prominently dominated by nanoscale building blocks.