Reduction Of Zinc Ions Research Articles

Hydrophilic and Insulative Interface Strategy Against Side Reactions for Dendrite‐Free Zinc Metal Anodes

AbstractThe zinc dendrite growth and the parasitic hydrogen evolution reactions (HER) hinder the commercialization of zinc batteries. To address this, a hydroxyl‐rich Boehmite coating (HR‐BC) strategy is developed that combines excellent electrical insulation and high zinc ion conductivity. The hydrophilic hydroxyl groups facilitate hydrogen bond formation with the hydrated zinc ions, accelerating the de‐solvation process and suppressing the HER. Additionally, the electrically insulative nature of Boehmite prevents the reduction of zinc ions within HR‐BC and results in preferential Zn deposition underneath it, leading to a dendrite‐free “sandwich structure” of HR‐BC//Zn deposition//Zn foil. Symmetric cells using HR‐BC‐Zn electrodes obtain an ultralong and stable cycling lifetime of 1700 h at 5 mA cm−2, along with a high cumulative plating capacity of 4250 mAh cm−2. When paired with a V2O5 cathode, the HR‐BC‐Zn anode demonstrates a high capacitance retention of 90% and an average Coulombic efficiency (CE) of 99.8% after 4000 cycles. Furthermore, when combined with a heteroatoms‐doped carbon (HDC) cathode, the HR–BC–Zn//HDC pouch‐type cell exhibits superior lifetime performance with nearly 100% average CE after 15000 cycles at 3.0 A g−1. This work highlights the effectiveness of hydrophilic and insulative coating strategies in fostering the progression of long‐lasting zinc‐based energy storage systems.

Phytomediated Synthesis of Zinc Oxide (ZnO) Nanoparticles via Vitex negundo Leaf Extract: Characterization, Antibacterial and Antibiofilm Activity

This study provides evidence for the green synthesis of zinc oxide nanoparticles (ZnO NPs) using Vitex negundo leaf extract. The UV–Visible (UV–Vis) spectrum of ZnO NPs and calcinated ZnO NPs (ZnO-C) showed peaks at 370[Formula: see text]nm and 374[Formula: see text]nm, respectively, confirming zinc ion reduction to zinc oxide. The ZnO NPs and calcinated counterparts were further characterized by FTIR, XRD, FE-SEM and EDX. FTIR results revealed the presence of alcoholic and aromatic groups, like flavonoids, in the leaf extract. The XRD pattern showed a distinctive Wurtzite crystalline phase with a hexagonal shape. The Brunauer–Emmett–Teller (BET) analysis data revealed that ZnO’s surface area and pore size is 22.8[Formula: see text]m2/g and 12.9[Formula: see text]nm, whereas ZnO-C exhibited a surface area of 23.5[Formula: see text]m2/g and pore size of 13.1[Formula: see text]nm. The SEM data demonstrated numerous irregular and agglomerated flakes fusing to form a roughly spherical morphology with the size, in the range of 15–20[Formula: see text]nm and 11–16[Formula: see text]nm for ZnO and ZnO-C NPs, respectively. The results of the antimicrobial assay by disc diffusion method and MIC testing revealed that ZnO and ZnO-C NPs exhibited moderate to high antimicrobial activity against various microorganisms, indicating their application against bacterial infection. In addition, the ZnO NPs significantly disrupted the biofilm of Bacillus cereus and Pseudomonas aeruginosa, as confirmed by CV assay and fluorescent microscopy.

Synthesis and Characterization of Zinc Oxide Nanoparticles at Different pH Values from Clinopodium vulgare L. and Their Assessment as an Antimicrobial Agent and Biomedical Application.

The current study attempts to evaluate the formation, morphology, and physico-chemical properties of zinc oxide nanoparticles (ZnO NPs) synthesized from Clinopodium vulgare extract at different pH values and to investigate their antimicrobial and biomedical application potential. The reduction of zinc ions to ZnO NPs was determined by UV spectra, which revealed absorption peaks at 390 nm at pH 5 and 348 nm at pH 9, respectively. The spherical morphology of the nanoparticles was observed using scanning electron microscopy (SEM), and the size was 47 nm for pH 5 and 45 nm for pH 9. Fourier-transformed infrared spectroscopy (FTIR) was used to reveal the presence of functional groups on the surface of nanoparticles. The antibacterial activity was examined against Staphylococcus aureus, Streptococcus pyogenes, and Klebsiella pneumonia via the agar-well diffusion method. Comparatively, the highest activities were recorded at pH 9 against all bacterial strains, and among these, biogenic ZnO NPs displayed the maximum inhibition zone (i.e., 20.88 ± 0.79 mm) against S. aureus. ZnO NPs prepared at pH 9 exhibited the highest antifungal activity of 80% at 25 mg/mL and antileishmanial activity of 82% at 400 mg/mL. Altogether, ZnO NPs synthesized at pH 9 show promising antimicrobial potential and could be used for biomedical applications.

Phyto-assisted synthesis of zinc oxide nanoparticles using mango (Mangifera indica) fruit peel extract and their antibacterial activity

A facile and eco-friendly procedure was developed to fabricate zinc oxide nanoparticles (ZnO NPs) using an aqueous extract of mango fruit peel (MFP), a by-product of agroindustry. The ZnO NPs were fabricated using zinc acetate as a precursor and MFP extract as a reducing and capping agent in a neutral environment (pH 7). The UV-visible spectrum supported the formation of ZnO NPs, showing a distinctive absorption peak at 368 nm. The presence of a ZnO crystalline phase was identified by X-ray diffraction (XRD) analysis. The Fourier transform infrared (FTIR) evaluation demonstrated that the biomolecules present in the MFP extract actively contributed to zinc ion reduction. According to the scanning electron microscopy (SEM) image, the surface morphology of ZnO NPs showed a mixture of spherical and flake-like shapes with particle sizes ranging from ~20 to ~90 nm. Based on antibacterial analysis using the agar diffusion method, the biosynthesized ZnO NPs at 3% w/v were active against Escherichia coli, Bacillus subtilis, and Staphylococcus aureus with diameter inhibitions of 8, 19, and 10 mm, respectively. In summary, this present work highlights that ZnO NPs can be synthesized using a by-product of agroindustry. More importantly, the biosynthesized ZnO NPs can be applied as an antibacterial agent.

Effect of Calotropis procera (Aiton) Dryand.based zinc oxide nanoparticles on the cotton pest Spodoptera litura Fab.

Major loss in agricultural crops is caused by insect pests. In India, various synthetic insecticides are used against pests. These are much expensive and cause environmental hazards. The nanoparticles, as an alternative approach is gaining considerable interest in this field. In the present study, we explored the biological synthesis of zinc oxide nanoparticles using Giant milkweed, Calotropis procera (Aiton) Dryand. and its effects on the tobacco cutworm, Spodoptera litura. The reduction of zinc ions (Zn2+) to zinc nanoparticles (ZnO NPs) was prepared by mixing 50 g of C. procera leaves with 100 mL of single distilled water in a 250 mL glass beaker. To synthesize nanoparticles, 50 mL of C. procera leaf extract was taken using a stirrer-heater and 5 g of zinc oxide was added at 60ºC, boiled, then kept in a hot air oven at 70ºC for 24 h. Finally, the obtained light yellow coloured powder was carefully collected and characterized using X-ray diffraction (XRD) analysis. The results revealed that the biologically synthesized zinc oxide nanoparticles pesticide was highly effective against the pest. The weight of the pest decreased from low concentration to high concentration. It is concluded that the Calotropis Procera based zinc oxide nanoparticles could be used for the control of Spodoptera litura.

Активация угольного электрода соединениями цинка

The process of cathodic polarization of a carbon electrode in an aqueous solution of zinc chloride with a concentration of 0,5 mmol/l in the potential range from equilibrium to –1,6 V was studied. It was found that staged reduction of zinc ions occurs in this region. At the initial moment after the completion of polarization, the potential of the carbon electrode was –1,2 V, later it increased to 0,8 V under the condition of stabilization in the electrolyte solution, and up to 1 V when the electrode was exposed to air for 15 min after polarization (then it was returned to aqueous electrolyte solution, where the potential increase occurred). To explain the potential shift phenomenon, a reaction scheme was proposed, where one of the stages is the formation of zinc peroxide on the surface of the working electrode. The carbon electrode modified with zinc in the course of further studies showed good reproducibility of electrochemical properties, which are proved by the cyclic current-voltage characteristics of cathodic and anode processes.

Ferroelectric Polymer-Based Composite Layer Coated Zinc Ion Batteries Toward Dendrite-Free Zinc Anodes

The lithium ion batteries are dominating rechargeable battery market with advantages of long cycle life, adaptability, and high energy density; however, disadvantages including lithium resource shortage, high processing cost arising from the other battery components (Co-based cathode and electrolyte), and safety concerns due to flammable organic electrolytes and highly reactive lithium species hinder further development to grid-scale batteries.The zinc ion batteries have been proposed as an alternative for lithium ion batteries owing to suitable electrochemical properties for grid-scale batteries of large specific capacity (820 mAh/g), high volumetric capacity (5854 mAh/cm3), and low redox potential (-0.76 V). Also, zinc’s low cost, environmental abundance, inexpensive mass production, and superior safety due to usage of aqueous electrolyte make zinc ion battery extremely promising for future battery applications.Prior to the commercialization of zinc ion batteries, a detrimental issue remains with rapid degradation of battery performance mainly due to dendrite formation and additional side reactions during charging and discharging processes. The dendrite growth in association with the reduction of zinc ions during the discharging process causes lifespan shortening related to short circuit arising from separator piercing as well as a decrease of capacity via unceasing of water/electrolyte decomposition accompanied with fast electrolyte depletion. Also, parasitic side reactions between electrode and electrolyte produce hydrogen and zinc sulfate hydroxide while wasting both electrolyte and zinc electrode. These reactions involves electron consumption which severely reduce a Coulombic efficiency and prohibit us from reaching theoretically expected electrochemical performances. Several strategies have been proposed to suppress the dendrite growth and side reactions, such as interfacial electrode modification through an increase of the surface area of zinc anodes, insertion of electrolyte additive, manipulation of crystallographic orientation of electrode.Here, we propose an additional ferroelectric layer coating onto the zinc electrode for the compression of dendrite growth and the hindrance of the side reaction. Among the ferroelectric materials, we select composites consisting of poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) and barium titanate nanoparticles to take both advantages of P(VDF-TrFE) — cost-effective fabrication, compatibility with battery components, and non-toxicity and of barium titanate — lead-free inorganic ferroelectric materials with high ferroelectricity. The 800 nm-thick P(VDF-TrFE)/barium titanate nanocomposite ferroelectric layer is spin-coated onto a bare zinc electrode and works as an anode for battery operation.A coated ferroelectric layer serves as a physical barrier to block zinc corrosion and hydrogen reaction. Meanwhile, dendrite suppression achieved by ferroelectric layer resulting from the uniform electric field and additional ionic path can be attributed to longer cycle life. Therefore, we could observe about three times extended cycle life and a decrease of side reaction products (hydrogen, zinc sulfate hydroxide) to the half value or less than bare zinc electrode.

Doxorubicin-Conjugated Zinc Oxide Nanoparticles, Biogenically Synthesised Using a Fungus Aspergillus niger, Exhibit High Therapeutic Efficacy against Lung Cancer Cells.

This study reports the therapeutic effectiveness of doxorubicin-conjugated zinc oxide nanoparticles against lung cancer cell line. The zinc oxide nanoparticles (ZnONPs) were first synthesised using a fungus, isolated from air with an extraordinary capability to survive in very high concentrations of zinc salt. Molecular analysis based on 18S rRNA gene sequencing led to its identification as Aspergillus niger with the NCBI accession no. OL636020. The fungus was found to produce ZnONPs via the reduction of zinc ions from zinc sulphate. The ZnONPs were characterised by various biophysical techniques. ZnONPs were further bioconjugated with the anti-cancer drug doxorubicin (DOX), which was further confirmed by different physical techniques. Furthermore, we examined the cytotoxic efficacy of Doxorubicin-bioconjugated-ZnONPs (DOX-ZnONPs) against lung cancer A549 cells in comparison to ZnONPs and DOX alone. The cytotoxicity caused due to ZnONPs, DOX and DOX-ZnONPs in lung cancer A549 cells was assessed by MTT assay. DOX-ZnONPs strongly inhibited the proliferation of A549 with IC50 value of 0.34 μg/mL, which is lower than IC50 of DOX alone (0.56 μg/mL). Moreover, DOX-ZnONPs treated cells also showed increased nuclear condensation, enhanced ROS generation in cytosol and reduced mitochondrial membrane potential. To investigate the induction of apoptosis, caspase-3 activity was measured in all the treated groups. Conclusively, results of our study have established that DOX-ZnONPs have strong therapeutic efficacy to inhibit the growth of lung cancer cells in comparison to DOX alone. Our study also offers substantial evidence for the biogenically synthesised zinc oxide nanoparticle as a promising candidate for a drug delivery system.

Short Communication: Characterization and biological synthesis of zinc oxide nanoparticles by new strain of Bacillus foraminis

Abstract. El-Ghwas DE. 2021. Short Communication: Characterization and biological synthesis of zinc oxide nanoparticles by new strain of Bacillus foraminis. Biodiversitas 23: 548-553. The production of ZnO Nanoparticles (ZnONPs) has gained a lot of interest because of its wide antibacterial and eco-friendly activity. This work was performed for the biosynthesis of ZnONPs using isolated bacteria strains. A new bacterial strain isolated from farm soil in Jeddah, Saudi Arabia, was identified by molecular identification using 16S ribosomal RNA. The isolated sequence had the highest similarity (99 %) with Bacillus foraminis. On the other hand, the appearance of white precipitate at the end of incubation time confirms the production of ZnONPs. Also, UV, TEM, and FTIR were used to investigate the stability and structure of ZnONPs. The absorbance of ZnONPs was measured at 386 nm in a UV experiment. TEM result revealed that the particles were polydisperse and usually spherical, with maximum particles in the 5.40 - 6.79 nm range. In addition, FTIR confirms the reduction of zinc ions by bacteria. This is the first report on the biosynthesis of ZnONPs by B. foraminis.

Synthesis of perovskite BaTaO2N with low defect by Zn doping for boosted photocatalytic water reduction

Perovskite BaTaO2N (BTON) is one of the most promising photocatalysts for solar water splitting due to its wide visible-light absorption and suitable conduction/valence bands, but it still confronts the challenge of high defect density causing decreased charge separation as well as photocatalytic activity. In this work, we develop a simple zinc doping strategy to greatly suppress its defect density and promote its water reduction performance. It is found that the defect formation on the nitrided Ba(Zn1/3-xTa2/3)O3-yNz (denoted as BZTON hereafter) will be greatly inhibited when the Zn-doped Ba(Zn1/3Ta2/3)O3 (BZTO) oxide is used as the nitridation precursor. The structural characterizations and discussion demonstrate that the effective inhibition of Ta5+ into Ta4+ defects in BZTON mainly results from the easy reduction of zinc ions into metal and further the evaporation of zinc metal under the thermal ammonia flow. Interestingly, this simply doping methodology can be easily extended into the synthesis of SrTaO2N (STON) with extremely low defect density, demonstrating its generality. Benefiting from the successful control to the defect density, the as-obtained BZTON photocatalyst exhibits remarkably promoted charge separation as well as water reduction activity to produce hydrogen with respect to the pristine BTON. Our work may provide an alternative avenue to prepare oxynitride semiconductors with reduced defect density for promoted solar energy conversion.

Synthesis of Metallic Zinc Nanoparticles by Reduction of Zinc Ions in Protonic Solvent

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.

Green synthesis of ZnO nanoparticles from Syzygium Cumini leaves extract with robust photocatalysis applications

The textile industry consumes excess water for their dyeing process and as a response, they are polluting water bodies. This toxic water is perilous to humans; lessen the aquatic plants' activity too. For the removal of dye toxicity, photocatalytic degradation activity is a practical method of interest. In this work, ZnO NPs were synthesized by biogenic synthesis. ZnO NPs bear the desired physicochemical properties in terms of structural, optical, thermal and photocatalytic properties. In this study, the leaf extract of Syzygium Cumini was used for the synthesis of nanoparticles for the removal of toxicity of MB dye with various properties like eco-friendly, cheap, non-toxic and low time-consuming properties. The aqueous leaf extract was put into the ZnO solution results in the change of colour from yellow to reddish-brown that indicates the reduction of zinc ions in the solution. The synthesized ZnO NPs were characterized by XRD, SEM, FTIR spectrum and UV–Vis spectrophotometer which was used to identify the crystallinity, morphology and functional group responsible for reducing and capping of synthesized ZnO NPs and photocatalytic degradation. The photocatalysis of synthesized ZnO NPs were observed by the degradation of methylene blue (MB, a toxic dye) under sunlight which follows pseudo-first-order kinetics. Synthesized nanoparticles effectively helpful in degrading the MB dye nearly 91.4% at pH 7 and 180 min of exposure time and under sunlight. By using this biogenic method, nanoparticles can be synthesized and used in the removal of other harmful dyes.

Understanding the zinc discharge from sodium sulphate solution in the presence of surfactants

This paper aims to understand the effect of surfactants on zinc discharge in sulphate solutions on a solid electrode and to collect new experimental data that would give a deeper insight into the processes involved in industrial electrolysis. Anionic and cationic coagulants (flocculants) and an anionic frother were used as surfactants. Electrolysis was conducted in the potential region of –1050 to –1250 mV (Ag/АgCl) in stationary and dynamic conditions in sodium sulphate solution under intensive stirring. The authors obtained comparative data on the zinc discharge current in electrolyte with and without frother at the scan velocities of 2 to 100 mV/sec. It is noted that at higher scan velocities (>10–20 mV/sec) and in the initial electrolysis phase the zinc discharge process develops in a mixed mode. In this case, as the study showed, the positive effect of the frother on zinc discharge is most distinguished. A reaction order was designed based on zinc ion with four potentials to prove that the zinc electrowinning process develops in a mixed mode. It is shown that the addition of frother raises the reaction order from 1.2 to 1.5, which is attributed to a larger effective cathode surface area. The data obtained in a galvanostatic mode under intensive stirring conditions indicate that, at the current density of 1.7 mA/cm2, the electrode polarization is 1.6 times lower in the presence of cationic coagulant and almost 3 times lower in the presence of anionic coagulant. The data given in this paper are also indicative of a changing electrolysis mode. Under stirring, a transition is observed from a diffusion mode of zinc ion reduction to a mixed one. The experimental data obtained under intensive stirring conditions in sodium sulphate solution with frother, as well as anionic and cationic coagulants are in line with the theory of electrochemical processes.

Sex differences, growth, reproduction and zinc ion homeostasis of zebrafish after chronic dietary l-selenomethionine exposure

Several mechanisms regarding the developmental and reproductive toxicity of l-selenomethionine (SeMet) in freshwater fish have been widely reported. However, limited information was available on endocrine-disrupting effects of SeMet. In this study, zebrafish larvae (day 24 post-fertilization) were exposed to environmentally-relevant levels of dietary SeMet (control, 1.11 ± 0.11, 3.59 ± 0.20, 10.80 ± 0.52, 29.19 ± 0.46, and 58.63 ± 0.70 μg Se/g d.w. diet) for 90 days until sexual maturity. For the first time, a gender difference in the effect of SeMet on body mass of zebrafish was observed. The lowest observed adverse effect level (LOAEL) in male was 10.80 ± 0.52 μg Se/g d.w., while it was 29.19 ± 0.46 μg Se/g d.w. in female. Chronic exposure to dietary SeMet reduced the percentage of early vitellogenic oocyte in female and the percentage of spermatid in male by inhibiting the growth hormone/insulin-like growth factors (GH/IGFs) and hypothalamus-pituitary-gonad (HPG) systems, which was characterized by significant decreases in the transcriptional levels of gh, igf1, era, and ar. Se content in the liver of male was significantly higher than that in female when dietary Se level reached 10.80 ± 0.52 μg Se/g d.w.. Furthermore, the zinc content in the livers and gonads of both female and male treated with 29.19 ± 0.46 and 58.63 ± 0.70 μg Se/g d.w. diets was significantly reduced. Reduction of zinc ion not only led to the significantly upregulated transcriptional levels of zip1 and znt2, but also downregulated transcriptional levels of znf219l and sp7. In summary, this study provides a new evidence that chronic exposure to high level of dietary SeMet (≥10.80 μg Se/g d.w.) could impair the development and reproduction of zebrafish with gender difference by interfering the GH/IGFs and HPG systems. Moreover, disruption of zinc ion homeostasis might exacerbate the toxicity of Se to zebrafish.

Electrochemical Studies of Amino Acid: Metal Ion Interactions

Introduction Previous studies (1-3) in this laboratory have involved electrochemical studies of the interaction of Zn(II) ions with L-cysteine in an attempt to more fully characterize the formation of “zinc finger” proteins (4). Subsequent work has involved similar investigations of L-histidine (5), and the work has now been extended to L-tryptophan. Clear evidence for the formation of Zn(II) complexes with L-cysteine and L-histidine has been obtained by cyclic voltammetric peak potential shifts for zinc ion reduction (2, 5). In the present study, we have extended this work to L-tryptophan by means of voltammetric studies of the amino acid and by investigation of its interactions with metals such as zinc and copper. Results for the interaction of bismuth(III) with L-cysteine and with glutathione, prompted by the significance of such interactions in human biochemistry (6-8), are also planned for presentation. Experimental L-Cysteine, L-glutathione, L-histidine, and MOPS (3-(N-morpholino)propanesulfonic acid) were obtained from Sigma-Aldrich Corporation, and L-tryptophan was obtained from Nutritional Biochemicals Corporation. Electrochemical experiments were carried out under nitrogen using a Gamry Instruments Interface 1000 potentiostat and Gamry Framework software. Working electrodes were obtained from BASi (Glassy carbon, 3.0 mm diameter; platinum 1.6 mm) and eDAQ (gold, 1.0 mm diameter). Potentials were measured with respect to a silver/silver chloride saturated KCl reference electrode (BASi). Results and Discussion Electrochemical studies of L-tryptophan in pH 7.4 phosphate buffer have shown that this amino acid undergoes oxidation at +0.82 V vs Ag/AgCl at 100 mV/s, which is a considerably less positive potential than that observed for L-histidine (5). The effects of L-tryptophan additions to ZnSO4 added to pH 7.4 MOPS buffer were found to be generally similar to those for L-histidine (5). For the case of interactions of L-cysteine with Bi(III) in pH 7.4 MOPS buffer, Bi(NO3)3 was added to pH 7.4 MOPS buffer resulting in the formation of slightly soluble hydroxyl bismuth complexes. Upon addition of 1:1 bismuth(III):L-cysteine, the solution appearance changed from cloudy to clear, and voltammetric currents increased substantially, indicating a strong interaction between bismuth(III) and L-cysteine. In addition, a negative voltammetric shift for the bismuth(III) reduction potential was observed, as was the case for the zinc(II):L-cysteine interaction (2). Further additions of L-cysteine were found to produce additional negative shifts for bismuth(III) reduction. Similar behavior for L-glutathione was observed. MALDI-TOF spectra for the 1:2 Bi(III):L-glutathione and similar complexes in aqueous solutions have been reported (10) and provide supporting evidence for the electrochemical results in the present study. A similar spectrum for the 1:2 Bi(III):L-glutathione complex in pH 7.4 MOPS buffer has been obtained in the present work.

A POTENT CYTOTOXICITY AND ANTIMICROBIAL ACTIVITY OF ZINC OXIDE NANOPARTICLES SYNTHESIZED BY LEAF OF IPOMOEA PES-CAPRAE (L.) R. BR.

Objective: The present study was conducted to investigate the cytotoxicity and antimicrobial activity of zinc oxide nanoparticles (ZnO NPs) synthesized as eco-friendly technique from the leaf extract of Ipomoea pes-caprae (L.) R. Br. against human lung adenocarcinoma (A549), brain tumor (U87) cells, and human pathogens Salmonella typhi, Staphylococcus aureus, Klebsiella pneumonia, Pseudomonas aeruginosa, and Bacillus subtilis.
 Materials and Methods: The work was carried out with varying precursor (plant extract) volume to optimize the synthesis of ZnO NPs and it was confirmed by ultraviolet (UV)-visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, scanning electron microscopy, and atomic force microscope (AFM) characterization techniques and evaluate its cytotoxicity activity by 3-(4,5-dimethyl-2- thiazolyl)-2,5-diphenyl--tetrazolium bromide assay method, antimicrobial activity by disk diffusion method.
 Results: A peak at 320 nm with maximum intensity was observed at temperature of 80°C with pH of 8.0 in UV-visible spectroscopy confirmed the formation of ZnO NPs and we calculate the size of ZnO NPs from XRD data found as 15.8 nm. The FTIR analysis evaluated that the presence of different functional groups is carboxyl, amine, and phenolic compounds of leaves extract which are involved in the reduction of zinc ions and acts as capping the ZnO NPs. AFM microgram confirms that ZnO NPs were in nanorange and spherical in nature. The cytotoxicity activity of A549 and U87 cell lines treated with various concentrations of ZnO NPs showed a dose-dependent increase in cell inhibition and the half maximal inhibitory concentration value was calculated to be 7.8 μg/ml. The antibacterial activity of selected pathogens shows higher zone of inhibition.
 Conclusion: The present study reveals that synthesized ZnO NPs capping with various bioactive compounds present in the leaf of I. pes-caprae show promising activity of cancer cell lines and antimicrobial agents; hence, further detailed study may lead to develop at a novel phytomedicine for the anticancer and antimicrobial drugs.

Retraction of “Composite of Zinc Using Graphene Quantum Dot Bath: A Prospective Material For Energy Storage”

The electrodeposition of a zinc–graphene composite has been achieved for the first time using a graphene quantum dot (GQD) electrode. At the GQD electrode, the electrochemical reduction of zinc ion is shifted to a lesser negative potential with the complementary anodic peak due to the oxidation of the composite shifted toward a positive potential as compared to zinc ion reduction in the GQD bath. The charge ratio of anodic to cathodic peaks is one that represents a gain of nearly ten percent over the conventional Zn/Zn2+ in the energy storage systems. In galvanostatic electrolysis, the deposition of zinc–graphene composite is carried out under neutral and acidic conditions. The X-ray diffraction of the electrolytically prepared composite shows distinct features of 2 theta reflection at 8° due to (001) plane of graphene, in addition to the characteristic reflections at 38.9°,43.2°, 54.3°, 70.1° and 90° arising from Zn at (002), (100), (101), (102) and (110). A large scale preparation of the zinc–graphene c...

Kinetics of Zinc Ion Removal from Wastewater By Electrocoagulation

In this work, the research focused on the removal of zinc ions from the synthetic wastewater by electrocoagulation (EC) with aluminum electrodes. The effects of current density, electrode spacing, initial concentration, wastewater pH and conductivity on the removal efficiency and energy consumption were systematically investigated. The results showed that the zinc removal efficiency increased with the increasing current density and residence time. With a relatively low energy consumption of 0.35 kWh/m3, all of zinc ions (50 mg/L) were removed from the synthetic wastewater within 20 minutes EC treatment, 8.3 mA/cm2 for current density, and 5.3 for pH. Later with an energy consumption of 0.88 kWh/m3, all of zinc ions (250 mg/L) were removed from the wastewater at EC time of 50 minutes. In addition, the kinetic study was applied to analyze the removal rate of zinc ions by EC at different current densities and initial concentrations. Different mechanisms of zinc removal were implied by comparing the results of the low initial concentration (≤ 250 mg/L) and the high one (≥ 500 mg/L). It was reasonable to conclude that, besides the co-precipitation effect of the aluminum hydroxide flocculation, the electrochemical reduction of zinc ions at the cathode also contributed to the zinc removal, especially at a high initial concentration.

Composite of Zinc Using Graphene Quantum Dot Bath: A Prospective Material For Energy Storage

The electrodeposition of a zinc–graphene composite has been achieved for the first time using a graphene quantum dot (GQD) electrode. At the GQD electrode, the electrochemical reduction of zinc ion is shifted to a lesser negative potential with the complementary anodic peak due to the oxidation of the composite shifted toward a positive potential as compared to zinc ion reduction in the GQD bath. The charge ratio of anodic to cathodic peaks is one that represents a gain of nearly ten percent over the conventional Zn/Zn2+ in the energy storage systems. In galvanostatic electrolysis, the deposition of zinc–graphene composite is carried out under neutral and acidic conditions. The X-ray diffraction of the electrolytically prepared composite shows distinct features of 2 theta reflection at 8° due to (001) plane of graphene, in addition to the characteristic reflections at 38.9°,43.2°, 54.3°, 70.1° and 90° arising from Zn at (002), (100), (101), (102) and (110). A large scale preparation of the zinc–graphene c...

A new graphene composite with a high coulombic efficiency

Abstract Zinc-graphene composite has been electrolytically produced for the first time using a graphene quantum dot (GQD) electrode. The electrochemical reduction of zinc ion at a GQD electrode is shifted to a lesser negative potential with the complimentary anodic peak due to the oxidation of the composite shifted towards a positive potential as compared to zinc ion reduction in the GQD bath. The coulombic efficiency of the composite represents a gain of nearly 10% over the conventional Zn/Zn2+ in the energy storage systems. In galvanostatic electrolysis, the deposition of zinc-graphene composite is carried out under neutral and acidic conditions. The X-ray diffraction of the electrolytically prepared composite shows distinct features of 2 theta reflection at 8° due to (001) plane of graphene, in addition to the characteristic reflections at 38.9°,43.2°, 54.3°, 70.1° and 90° arising from Zn at (002), (100), (101), (102) and (110). A large scale preparation of the zinc-graphene composite has been achieved at a zinc plate as the working electrode in the GQD bath. The composite is stable up to 250 °C. Scanning electron microscopic (SEM) and energy dispersion X-ray analysis (EDAX) shows a string like structure with peaks for carbon and zinc in EDAX.