Presence Of Zinc Oxide Research Articles

Properties of a new renewable sesame protein adhesive modified by urea in the absence and presence of zinc oxide

Sesame protein (SP) is a new renewable resource for wood adhesives because of its brilliant performance, which is non-toxic and harmless to human health during the process of using plywood.

Effects of zinc supplementation on Shiga toxin 2e-producing Escherichia coli in vitro.

Swine edema disease is caused by Shiga toxin (Stx) 2e–producing Escherichia coli (STEC). Addition of highly concentrated zinc formulations to feed has been used to treat and prevent the disease, but the mechanism of the beneficial effect is unknown. The purpose of the present study was to investigate the effects of highly concentrated zinc formulations on bacterial growth, hemolysin production, and an Stx2e release by STEC in vitro. STEC strain MVH269 isolated from a piglet with edema disease was cultured with zinc oxide (ZnO) or with zinc carbonate (ZnCO3), each at up to 3,000 ppm. There was no effect of zinc addition on bacterial growth. Nonetheless, the cytotoxic activity of Stx2e released into the supernatant was significantly attenuated in the zinc-supplemented media compared to that in the control, with the 50% cytotoxic dose values of 163.2 ± 12.7, 211.6 ± 33.1 and 659.9 ± 84.2 after 24 hr of growth in the presence of ZnO, ZnCO3, or no supplemental zinc, respectively. The hemolytic zones around colonies grown on sheep blood agar supplemented with zinc were significantly smaller than those of colonies grown on control agar. Similarly, hemoglobin absorbance after exposure to the supernatants of STEC cultures incubated in sheep blood broth supplemented with zinc was significantly lower than that resulting from exposure to the control supernatant. These in vitro findings indicated that zinc formulations directly impair the factors associated with the virulence of STEC, suggesting a mechanism by which zinc supplementation prevents swine edema disease.

Photocatalytic degradation of indigo carmine by ZnO photocatalyst under visible light irradiation

In this work, the photocatalytic degradation of indigo carmine (IC) using zinc oxide suspension was studied. The effect of influential parameters such as initial indigo carmine concentration and catalyst loading were studied with the effect of Vis irradiation in the presence of reused ZnO was also investigated. The increased in initial dye concentration decreased the photodegradation and the increased catalyst loading increased the degradation percentage and the reused-ZnO exhibits lower photocatalytic activity than the ZnO catalyst. It has been found that the photocatalytic degradation of indigo carmine obeyed the pseudo-first-order kinetic reaction in presence of zinc oxide. This was found from plotting the relationship between ln (C0/Ct) and irradiation the rate constant of the process.UV- spectrophotometer was used to study the indigo carmine photodegradation.

Effect of ethyl cellulose on thermal resistivity of thixotropic ZnO nano-particle paste for thermal interface material in light emitting diode application

A large amount of heat trapped inside Light Emitting Diode (LED) is the consequence of large thermal resistance between the heat source and the heat sink. Zinc oxide (ZnO) thick film was screen-printed from thixotropic paste that consisted of binder, filler and solvent to act as thermal interface material. Structural, surface morphology, vibrational and thermal properties of the samples were studied by means of Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Measurement (AFM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermal Transient Tester (T3ster). XRD analysis revealed that the formation of hexagonal wurtzite ZnO powder, which is free of hydroxide. FESEM results indicated that 50wt% of filler loading in the thick film had created longer thermal transportation chain. The surface roughness of thick film displays variation in the range of from 64.8 to 218nm. The presence of ZnO and binder were confirmed by FTIR spectrum at 518cm−1 and 668cm−1 to 2974cm−1, respectively. Thermal characterization reveals a drop in film’s resistivity with the higher content of filler loading of 50wt% and 55wt%. The lowest rise in junction temperature of tested LED is reported to be 14.7°C of 50wt% of filler loading.

Synthesis of ZnO nanoparticles using Melia dubia leaf extract and its characterisation.

The present work deals with the synthesis of zinc oxide (ZnO) nanoparticles (Nps) using the biocompounds extracted from Melia dubia leaves (MD L.) and zinc acetate as precursors. The choice of the precursors was based on the intention to use the synthesised ZnO Nps for the healthcare applications. In this line, the antimicrobial property of ethanolic extract of MD L., uncalcined ZnO Nps and calcined ZnO Nps has been assessed and compared. The prepared particles have been characterised by comparing their Fourier transform infrared spectrum, X-ray diffraction (XRD) diffractogram and TEM images. The presence of ZnO has been confirmed using IR spectrum. The crystal structure and crystallite size have been found out using XRD diffractogram, and the obtained crystallite size was confirmed using TEM images. Finally, an attempt has been made to correlate the structure with the antimicrobial property of the material.

Simultaneous synthesis of nano ZnO and surface modification of polyester fabric

In this study, synthesis of zinc oxide nanoparticles was carried out along with the hydrolysis of polyester fabric using sodium hydroxide to increase the surface activity and enhance the nanoparticles adsorption. The polyester fabrics were treated with zinc acetate and sodium hydroxide at different bath conditions, ultrasound and stirrer, resulting in formation of ZnO nanospheres and ZnO nanorods. The presence of zinc oxide with different shapes on the surface of the polyester fabrics was confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Also, the X-ray diffraction patterns established the composition of wurtzite structure of zinc oxide. The self-cleaning property of treated polyester fabrics was evaluated through discoloring dye stain under sunlight irradiation. The antibacterial activities of the samples against two common pathogenic bacteria including Escherichia coli and Staphylococcus aureus were also assessed. The results indicated that the photocatalytic and antibacterial activities of the ultrasound treated polyester fabrics were superior compared to the stirrer treated samples.

Nanoparticules Mass Effect of ZnO on the Properties of Poly(4-Chloroaniline)/Zinc Oxide Nanocomposites

4-Chloroaniline (4ClAni) in the presence of zinc oxide (ZnO) nanoparticles were prepared by chemical oxidative polymerization in hydrochloric acid solution using Ammonium persulfate as oxidant. The effects of amount of ZnO nanoparticles (1, 1.5, 2, 2.5 and 3 g, respectively) on the properties of products were investigated. The obtained nanocomposites was characterized using XRD, IR, UV–visible, and XPS which confirmed the incorporation of the nanoparticle ZnO in the P(4ClAni) matrix and the maximum interaction occurs for 2 g ZnO loading. The TGA analysis was used to confirm the thermal stability and number of water molecules in each nanocomposites chain unit. Although the incorporation of ZnO nanoparticles reduces the electric conductivity of the P(4ClAni), the resulting nanocomposites still keep high conductivities, ranging between 2.19 × 10−2 and 5.92 × 10−4 S cm−1. Good electrochemical response has been observed for samples of amounts ZnO less than 2 g; the observed redox processes indicate that the polymerization on ZnO nanoparticles produces electroactive polymers. The P(4ClAni) layer adhered well to the ZnO nanoparticles and can be used as practical applications.

Effect of reduced graphene oxide-hybridized ZnO thin films on the photoinactivation of Staphylococcus aureus and Salmonella enterica serovar Typhi

The immobilization of photocatalyst nanoparticles on a solid substrate is an important aspect for improved post-treatment separation and photocatalyst reactor design. In this study, we report the simple preparation of reduced graphene oxide (rGO)-hybridized zinc oxide (ZnO) thin films using a one-step electrochemical deposition, and investigated the effect of rGO-hybridization on the photoinactivation efficiency of ZnO thin films towards Staphylococcus aureus (S. aureus) and Salmonella enterica serovar Typhi (S. Typhi) as target bacterial pathogens. Field-emission scanning electron microscopy (FESEM) revealed the formation of geometric, hexagonal flakes of ZnO on the ITO glass substrate, as well as the incorporation of rGO with ZnO in the rGO/ZnO thin film. Raman spectroscopy indicated the successful incorporation of rGO with ZnO during the electrodeposition process. Photoluminescence (PL) spectroscopy indicates that rGO hybridization with ZnO increases the amount of oxygen vacancies, evidenced by the shift of visible PL peak at 650 to 500nm. The photoinactivation experiments showed that the thin films were able to reduce the bacterial cell density of Staph. aureus and S. Typhi from an initial concentration of approximately 108 to 103CFU/mL within 15min. The rGO/ZnO thin film increased the photoinactivation rate for S. aureus (log[N/No]) from −5.1 (ZnO) to −5.9. In contrast, the application of rGO/ZnO thin film towards the photoinactivation of S. Typhi did not improve its photoinactivation rate, compared to the ZnO thin film. We may summarise that (1) rGO/ZnO was effective to accelerate the photoinactivation of S. aureus but showed no difference to improve the photoinactivation of S. Typhi, in comparison to the performance of ZnO thin films, and (2) the photoinactivation in the presence of ZnO and rGO/ZnO was by ROS damage to the extracellular wall.

Application of ZnO Nanoparticles for Improving the Thermal and pH Stability of Crude Cellulase Obtained from Aspergillus fumigatus AA001.

Cellulases are the enzymes which are responsible for the hydrolysis of cellulosic biomass. In this study thermal and pH stability of crude cellulase has been investigated in the presence of zinc oxide (ZnO) nanoparticles. We synthesized ZnO nanoparticle by sol-gel method and characterized through various techniques including, X-ray Diffraction, ultraviolet-visible spectroscope, field emission scanning electron microscope and high resolution scanning electron microscope. The crude thermostable cellulase has been obtained from the Aspergillus fumigatus AA001 and treated with ZnO nanoparticle which shows thermal stability at 65°C up to 10 h whereas it showed pH stability in the alkaline pH range and retained its 53% of relative activity at pH 10.5. These findings may be promising in the area of biofuels production.

Surface functionalization of rubber latex nanoparticles with sulfidosilane moieties

ABSTRACTPolybutadiene latex particles were functionalized with bis[3‐(triethoxysilyl) propyl] tetrasulfide (TESPT) in the presence of zinc oxide as an activator and ethanol as a co‐solvent. The success of this reaction was confirmed both by the peaks attributed to Si‐O groups at 1085 and 1110 cm−1 and C‐S bond at 630 cm−1 which appeared after reaction in Attenuated Fourier Transform Infrared (ATR‐FTIR) Spectra and also by increasing in the particle size diameter of latex particles (from 95 to 127 nm) in Dynamic Light Scattering analysis. X‐ray Diffraction results also showed changes in crystalline structure of the modified particles (as a strong decrease in the intensity of peak at 2θ=19.54). The effect of reactant concentration in a constant amount of TESPT (by varying the water and ethanol content), reaction time, activator size (micro and nanoparticles), and pH (≈7, 8.5) were investigated on degree of grafting (obtained from thermogravimetric analysis and ATR‐FTIR spectra), particle size diameter, cross‐link density, and swelling ratio of the samples. The amounts of silane grafting and cross‐link density of polymer particles were increased by an increase in the reaction time. The highest grafting degree was observed at low concentration of TESPT. Silane functionalization was also improved in a slight basic condition (pH=8.5) rather than neutral pH. The grafting reaction took place such as sulfur pre‐vulcanization and the possible mechanism of this reaction was discussed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43268.

Environmental Applications of ZnO Materials.

This review article comprehensively discusses the recent development of various environmental applications of Zinc Oxide (ZnO) semiconductor materials. The synthesis of various nano/micro structured ZnO using different methods and the influence of various preparation conditions on ZnO morphology are discussed. The environmental applications of nano/micro structured zinc oxide as an adsorbent, photocatalyst, and catalyst in catalytic ozonation processes are discussed. The adsorption of various organic pollutants and metal ions on the ZnO surface at different conditions are discussed. The ZnO assisted photocatalytic degradation of pollutants, water splitting, and disinfection under various conditions are reported on. Ozonation in the presence of zinc oxide and its influence on the removal of pollutants are also included.

One‐Pot Formation of ZnO‐graft‐Poly(d,l‐Lactide) Hybrid Systems via Microwave‐Assisted Polymerization of d,l‐Lactide in the Presence of ZnO Nanoparticles

The surface modification of inorganic nanoparticles by polymer grafting is generally required for obtaining well dispersed polymer‐based (bio)nanocomposites, and the in situ polymerization of corresponding monomers is considered to be a versatile approach to this purpose. In this work, the microwave‐assisted ring‐opening polymerization of d,l‐lactide in the presence of zinc oxide (ZnO) nanoparticles affords an original and straightforward method for generating ZnO‐graft‐poly(d,l‐lactide) hybrid systems. The influence of ZnO particle size and concentration on polymerization kinetics and molar masses of free poly(d,l‐lactide) (PLA) chains is analyzed. Several physico‐chemical techniques, including proton nuclear magnetic resonance (1H NMR), Fourier‐transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and thermogravimetric analysis, are used to characterize intermediates and/or reaction products. Taking into account the kinetic and spectroscopic investigation, competitive chemical pathways based on grafting from and grafting onto reactions are proposed for the one‐pot formation of PLA‐grafted ZnO nanoparticles. image

Optical Studies on the Effect of Different Layers of TiO<sub>2</sub> Seeded-Template to the Growth of Nanostructured ZnO

In this study, Zinc oxide (ZnO) nanostructures have been fabricated on glass substrates coated with Titanium dioxide (TiO2) of different layers, which act as seeded-template, by a solution-immersion method. The substrates were coated with TiO2 by using sol-gel spin coating at five different layers of TiO2: 1, 3, 5, 7 and 9. The effects of the layers to the growth of ZnO nanostructures were observed by using Ultraviolet-Visible (UV-Vis) spectroscopy, Raman spectroscopy and Photoluminescence (PL) spectroscopy. UV-vis spectra of films display the increasing of absorbance properties at visible region as the TiO2 layers increase, as well as at UV region. Meanwhile, at visible region the transparency of TiO2: ZnO films reduce as the layers of TiO2 increase from 1 layer to 9 layers. Raman analysis shows the presence of ZnO in all the TiO2 seeded-templates. From the result, it is confirmed the existence of mixed crystalline structure of both materials in these TiO2: ZnO thin films and PL spectra of the films show seeded TiO2 thin films has lower intensity of visible emission and high ratio of IUV/IVIS compared to the non-seeded TiO2 This contributes to the lower structural defects, oxygen vacancies, impurities and has the most improved optical properties.

Hydrogen production by methanol steam reforming: Catalytic performance of supported-Pd on zinc–cerium oxides’ nanocomposites

Two series of supported palladium catalysts (2wt%) were prepared on ZnO–CeO2 nanocomposites (Zn-to-Ce atomic ratio between 0.5 and 2) obtained by oxalate or carbonate coprecipitation (OC and CC series, respectively). Methanol steam reforming (MSR) reaction was tested in a wide range of temperature (398–623K) for CH3OH/H2O=1/1 gas mixtures. Pd on pure CeO2 was only able to decompose methanol to CO, under 523K, but the reverse water gas shift reaction took place at higher temperatures. The MSR reaction only occurred in the presence of zinc oxide and the selectivity to CO2 was higher for the CC series, due to the better dispersion of the ZnO phase over these carbonate-derived nanocomposites. Although the CO2 selectivity seems to be modulated by the reverse water gas shift reaction, the palladium supported on the mixed oxides was more stable than Pd/ZnO, which continuously deactivated. A detailed characterization by high resolution atomic microscopy, X-ray photoelectron spectroscopy and a novel carbon monoxide step chemisorption technique, proved the formation of bulk and surface PdZn alloying in the ternary catalyst, Pd supported on the nanosized ceria and zinc oxide supports. It is concluded that although a better catalytic stability was observed on the ZnO–CeO2 nanocomposites, the employment of temperatures higher than 450K would impose an insurmountable limitation in terms of CO2 selectivity.

English

In this study, the photocatalytic degradation of batik wastewater in the presence of zinc oxide (ZnO) as photocatalyst was investigated. The effect of various operating parameters, such as pH of batik wastewater, catalyst dosage and aeration on the photocatalytic degradation process, was examined. The mineralization of batik wastewater was also evaluated through chemical oxygen demand analysis. The decolorization of batik wastewater was enhanced at acidic conditions (pH3) which was 88.2% after 10 h irradiated under solar light, meanwhile its mineralization was 286 mg/L after 12 h irradiation time. The data obtained for photocatalytic degradation of batik wastewater was well fitted with the Langmuir-Hinshelwood kinetic model. It can be concluded that batik wastewater could be decolorized and mineralized under solar light irradiation with presence of ZnO.

Effect of zinc oxide on the viscosity and adhesion property of epoxidized natural rubber/acrylonitrile‐butadiene rubber‐based pressure‐sensitive adhesives

Viscosity, loop tack, peel strength, and shear strength of epoxidized natural rubber (ENR 50)/acrylonitrile‐butadiene rubber (NBR)–based pressure‐sensitive adhesive were studied in the presence of zinc oxide. The zinc oxide concentration was varied from 10 to 50 parts by weight per hundred parts of rubber (phr). Coumarone–indene resin with loading of 40 phr was chosen as the tackifier resin. Toluene and polyethylene terephthalate were used as the solvent and coating substrate, respectively, throughout the experiment. The adhesive was coated on the substrate by using a SHEEN hand coater. Viscosity of the adhesive was determined by a Brookfield Viscometer, whereas the loop tack, peel strength, and shear strength were measured by a Lloyd Adhesion Tester operating at 30 cm/min. Results indicate that viscosity increases with zinc oxide concentration owing to the concentration effect. Loop tack and peel strength pass through a maximum value at 20 phr of zinc oxide concentration. This observation is associated with the effect of varying degrees of wettability of the adhesive on the substrate. Shear strength, however, increases steadily with increasing zinc oxide loading owing to the steady increase in cohesive strength. In all cases, the adhesion properties of adhesives increase with increasing coating thicknesses. J. VINYL ADDIT. TECHNOL., 22:410–414, 2016. © 2015 Society of Plastics Engineers

Structural and morphological properties of HA-ZnO powders prepared for biomaterials

Abstract The purpose of this study was to investigate the structural and morphological properties of hydroxyapatite – zinc oxide (HA-ZnO) powders prepared to be used in an endodontic sealer formulation. The HA-ZnO was synthesized from hydroxyapatite (HA) in the presence of zinc oxide (ZnO) sol. The starting reagents were CaO, H3PO4 and a suspention of ZnO (25% in water). Following precipitation, the obtained sol was subjected to heat treatment at 110°C, 400°C, 850°C and 1050°C. The study focused on the influence of the thermal treatment on the cristallinity of precipitated powders. X-ray diffraction was used in order to study the structural properties of the obtained powder. Fourier Transform Infrared Spectroscopy (FT-IR) was used in order to evaluate the interactions between HA and ZnO. The morphology of the samples was studied by Scanning Electron Microscopy (SEM). Transmission Electron Microscopy and High Resolution Transmission Electron Microscopy (TEM, HRTEM) were used for the determination of particle size and fractal analysis. The fractal analysis of images using the standard box-counting method is presented and the results are discussed. It was demonstrated that the fractal dimension analysis is a useful method to quantitatively describe the complex microstructures and it can reveal the relation between fractal parameters.

Anticancer activity of fungal l-asparaginase conjugated with zinc oxide nanoparticles

Demand for developing novel delivery system for cancer treatment has increased due to the side effects present in intravenous injection of L-asparaginase. Nanoparticles are used for delivering the drugs to its destination in cancer cure. Nanobiocomposite of zinc oxide nanoparticles conjugated with L-asparaginase was produced by Aspergillus terreus and was confirmed using maximum UV-Vis absorption at 340 nm in the present work. The presence of functional groups like OH, C-H, -C=N and C=O on the surface of nanobiocomposite was found from Fourier transform infrared spectrum analysis. Size of the produced nanocomposite was found in the range of 28-63 nm using scanning electron microscope. The crystalline nature of the synthesized nanobiocomposites was confirmed by X-ray diffraction analysis. The presence of zinc oxide on synthesized nanobiocomposite was confirmed by energy dispersive spectrum analysis. The anti-cancerous nature of the synthesized zinc oxide conjugated L-asparaginase nanobiocomposite on MCF-7 cell line was studied using MTT assay. The viability of the MCF-7 cells was decreased to 35.02 % when it was treated with L-asparaginase conjugated zinc oxide nanobiocomposite. Hence it is proved that the synthesized nanobiocomposites of zinc oxide conjugated L-asparaginase has good anti-cancerous activity.

Resistance to Thermal Degradation of Polypropylene in Presence of Nano Zinc Oxide

Polypropylene/zinc oxide composites were prepared using melt mixing method and made into sheets using compression moulding. 0–5 wt% of zinc oxide (ZnO) with different crystallite sizes were incorporated into the polypropylene (PP). Mechanical properties of the PP were increased by the addition of ZnO. Morphology of the composites showed good dispersion of ZnO in the composites. Thermal ageing was carried out on neat PP and composites for 24 hrs. Mechanical properties of the PP and composites were decreased after thermal ageing. However composites showed increased properties compared to neat PP even after thermal ageing. IR studies indicated better thermal stability of PP in presence of ZnO. PP filled with less crystallite size ZnO showed better properties compared to PP filled with high crystallite size ZnO and neat PP.

Degradation of High Level m‐Cresol by Zinc Oxide as Photocatalyst

In this study, the high concentration of m‐cresol as a sample of organic pollutants was degraded in the presence of zinc oxide and UV irradiation during 6 h at laboratory scales. The amount of photocatalyst, pH and m‐cresol concentration were considered as effective factors on the photodegradation. The demineralization of m‐cresol was measured by UV–Vis spectrophotometry while the total organic carbon‐analyzer was used to determine the mineralization. The ultrahigh performance LC was used to identify probable intermediates. The results showed optimum condition at pH 7–9, which is the natural pH of industrial wastewater. Moreover, 100% of m‐cresol was removed after 5 h of irradiation time, which is quite significant. The detected intermediates were 3,5‐hydroxytoluene, 2,5‐hydroxy‐benzaldehyde, and 3‐hydroxy‐benzaldehyde after 3 h of reaction time. Reusability of the photocatalyst showed insignificant reduction in the photo‐catalytic performance. In conclusion, this investigation indicated high potential of zinc oxide suspension to remove high level concentration of m‐cresol under UV irradiation.