Papers by Keyword: ZnO Nanoparticle

Abstract: Red Grapes or Red Globe (Vitis vinifera Linn.) is a delicate fruit easily damaged and bruised. The changes in the texture of Red Globe flesh and shrinkage happened if it kept too long, even in the low temperature. This condition is disadvantageous, especially for fruit sellers or vendors. Therefore, the edible coating is important to help the fruit's freshness by protecting its surface with its coating. Starch is one of the sources of an edible coating obtained from jackfruit seed since it contains 52.53% of amylase. This study aimed to examine the potential of jackfruit seed starch as an edible coating for the preservation of Red Globe. Furthermore, the incorporation of ZnO nanoparticles in the edible coating matrix was also examined for vitamin C of the Red Globe since ZnO has selective toxicity toward bacteria. The edible coating incorporated with ZnO nanoparticle was characterized based on ash content, water content, FTIR, and SEM. The results showed that ZnO nanoparticle was successfully incorporated in the edible coating matrix. In addition, the effect of edible coating on Red Globe freshness was also observed.

Abstract: Metal corrosion generally refers to metal deterioration process that is caused by electrochemical reactions between the metallic substrate with corrosive environment. Marine grade stainless steel type 316L (SS 316L) is a premium material for marine applications. Prolonged exposure to chloride-containing environments increases the susceptibility of unprotected SS 316L to localized corrosion namely pitting and crevice corrosion. In this study, the potential protective coating comprising of the epoxy matrix with ZnO nanoparticles combination was formulated and its anticorrosive properties on SS 316L substrate were analyzed. Variation in corrosion behaviour of SS 316L coated with a series of epoxy coating solution containing 1, 3, 5, 7 and 10 wt % ZnO nanoparticles were thoroughly observed. The coating formulations were characterised by using X-ray Diffraction (XRD) spectroscopy and Scanning Electron Microscope (SEM). Meanwhile, the corrosion performance testing was measured by using Potentiodynamic Polarization (PP) technique. The results revealed that epoxy coating incorporated with 3 wt % of ZnO nanoparticles provided the best corrosion protection on SS 316L as the corrosion rate for the metal substrate has been minimized from 0.05268 mm/year to as low as 0.00047 mm/year after coating. Dispersion of ZnO nanoparticles in epoxy matrix increases the barrier properties of the coating and impeded corrosion process on SS 316L through suppression of anodic reaction.

Abstract: Zinc oxide nanoparticles (ZnO-NPs) were successfully prepared by hydrothermal method at low temperatures (80°C) for 2 hours using zinc nitrate as starting materials. The average size of hydrothermally synthesized ZnO-NPs were comparable with commercial one as confirmed by Particle Size Analyzer (PSA). The incorporation of hydrothermally synthesized ZnO-NPs (0.5% and 1%, w/w) and glycerol as plasticizer (20%, w/w) into tapioca starch film significantly reduce water absorption capacity and water vapor transmission rate while increasing tensile strength and elongation at break of the composite film. These results suggest that hydrothermally synthesized ZnO-NPs have the potential as nanofiller to improve the physical and mechanical properties of biobased film.

Abstract: The objective of this study was to develop biopolymer based films as alternative of synthetic petroleum based-packaging. The ZnO NPs (0.5 and 1% ^w/_w carrageenan) and beeswax (3% ^v/_v), as hydrophobic component, were incorporated into carrageenan polymer to produced bionanocomposite films. The resulting films were characterized using SEM. The physical and mechanical properties of films were also investigated. The addition of ZnO NPs and beeswax resulted in different morphological surface as well as influenced the surface color of carrageenan film. Incorporation of ZnO NPs increased TS and EAB of the film, while WVTR decreased. Furthermore, the presence of beeswax within the carrageenan and or its nanocomposite films promoted synergistic effect with ZnO NPs in reducing WVTR and EAB, however decreased TS of films. Therefore, these bionanocomposite films were potentially used in packaging industry to maintain the quality of food stuffs.

Abstract: In this paper, the synthesis and characterisation of ZnO nanoparticles have been carried out for textiles applications. The ZnO nanoparticles have been synthesized by precipitation method. This technique is based on precipitation procedure by using zinc nitrate and sodium hydroxide as precursors. The scanning electron microscopy, dynamic light scattering, UV-Visible spectrophotometry and X-ray diffraction were used to characterize the particle size and morphology. The synthesized ZnO nanoparticles were spherical with the size in the range of 200-400 nm. Next step, the ZnO nanoparticles were directly applied on to the fabric using pad-dry-cure method. Finally, the antibacterial efficiency of modified fabrics was quantitatively evaluated and compared against gram-negative Escherichia coli and aerobic gram-positive Staphylococcus aureus according to AATCC 147. The results showed that the modified fabric demonstrated significant antibacterial activity against Escherichia coli and Staphylococcus aureus. These results suggest that synthesized ZnO nanoparticles could be used effectively for textiles applications.

Abstract: Zinc acetate as starting material along with diethanolamine as a stabilizer and isopropyl as a solvent were used in ZnO precursor preparation while p-type silicon was used as a substrate in this work. ZnO thin films were deposited on silicon wafer by spin coating deposition method. Samples were annealed at different temperature in range 500°C to 800°C. In other to study the surface morphology of thin film, Field Emission Scanning Microscopic (FESEM) was employed for every sample. It was found that, the thin films are composed by ZnO nanoparticles with size of about 18.3 nm to 32.95 nm. Topology of ZnO thin films was characterized by atomic force microscopy (AFM). In other to study the photoluminescence properties, 325 nm of xenon lamp was used as sources within range of 350 nm and 600 nm. It is found that two peaks are appears for the entire sample with the high intensity peak at 373 nm originated from the contribution of near band edge recombination from ZnO and low intensity at 573 nm was corresponding to ZnO defects.

Abstract: In the current study, bamboo rayon fabrics grafted with mixture of acrylic acid and acrylamide was utilized as a backbone to immobilize ZnO nanoprticles. The swollen grafted fabric was treated with ZnCl₂ followed by conversion of Zn²⁺ ions into ZnO nanoparticles. The modified product was characterized using FTIR, TGA and SEM and then evaluated for antibacterial activity against gram positive and gram negative bacteria as well as durability of their antibacterial activity after washing. The product showed antibacterial activity against both types of bacterias which was found to be durable till 40 washes. The modified material also showed improved UV protection because of presence of ZnO nanopartcles. The product can be claimed as suitable sustainable candidate for textile products in health and well being of the users.

Abstract: Supercapacitors have been successfully fabricated using nano-sized ZnO/nanoporous carbon (nano-sized ZnO/NPC) electrodes and various hydrogel electrolytes. The nano-sized ZnO/NPC materials have been prepared from zinc acetate (Zn(CH3COO)2) and coconut shell using a simple heating method. Polyvinyl alcohol (PVA) hydrogel blended with phosphoric acid (H3PO4), lithium hydroxide (LiOH) and sodium sulfate (Na2SO4) electrolytes, respectively, has been located between the electrodes. Two of the nano-sized ZnO/NPC electrodes with area of 1 cm2 and those PVA hydrogel electrolytes were pressed together and annealed at 60 °C for 60 min. to construct the supercapacitors. It has been found that the supercapacitor with nano-sized ZnO/NPC electrodes and Na2SO4 electrolyte has the highest capacitance of 60.4 Fg-1.

Abstract: Pure ZnO and Ag, Co doped ZnO nano particles [Zn1-xAgxCoyO, where x = 0.00 and 0.05, y = 0.05] were synthesized by chemical co precipitation method without use of surfactant. All the prepared samples calcinated in 1 hour at 500oC, after that the morphology of the samples were evaluated by Scanning Electron Microscope (SEM). The X- ray diffraction (XRD) results indicated that the synthesized co-doped ZnO nano crystals had the pure hexagonal structure without any significant change in the structure affected by Ag and Co substitution. Dopant elements Ag and Co are present in the ZnO host material and conformed by Energy Dispersive Analysis of X-ray Spectra (EDAX). The incorporation of Ag+ in the place of Zn2+ has made a considerable decrease in the size of nano crystals as compared to pure ZnO nano particles (It is to be noted that Co should be kept constant at 5 mol %). Blue emission was observed by Photo Luminescence (PL) Spectra.

Abstract: The widespread use of nanoparticles (NPs) in consumer goods could put these materials in the waste stream, potentially to soil and sediments. However, little is known about their transport in water and soils. In this study, transport behavior and attachment of ZnO NPs in soil components were studied through column experiments and sequential extraction, respectively. Bare and sodium citrate coated ZnO NP suspended in CaCl2 solutions at different ionic strengths, were passed through glass columns packed with sandy soils (SS) and sandy loam soils (SLS) and the effluents were analyzed by ICP-OES. The distribution of Zn in soil particles was studied by electron microprobe (EMP). Results showed that 99% of Zn/ZnO NPs was retained in SLS and 68% ~ 99% was retained in SS, for ionic strengths varying from 0 to 1 mM. Travel distances (cm) for bare ZnO NPs in SS and SLS were 19.2 and 5.3, respectively, while for coated NPs the distances were 21.4 and 6.9 cm, respectively. The surface coating reduced deposition rates from 0.73 to 0.65 and from 2.28 to 1.74 for SS and SLS, respectively. In both soils the amounts of uncoated NPs in the exchangeable fraction were less than 1%; however, 30% of coated NPs remained in the exchangeable fraction. EMP mapping showed that Zn/ZnO NPs associated with silica and aluminum, which are indicators of soil clay minerals. Long term observations are still needed to evaluate the bioavailability to plants of Zn released from coated and uncoated ZnO NPs.