Papers by Keyword: Hot Water Treatment

Abstract: Sol-gel precursor has been prepared by using zinc acetate (ZnAC) as starting material dissolved in isopropanol (IPA), diethanolamine (DEA) and distilled water (H₂O) were added to produce a homogeneous and stable solution. The sol-gel precursor was deposited on ITO/PET substrate by spin-coat route. Oxidation process was held in deionized water at 90 °C for a specific time. The (100) and (101) ZnO planes were formed as the preferred orientation. RMS values of ZnO samples found to be 280 nm, 272 nm and 241 nm for 8 h, 12 h and 16 h, respectively by hot water treatment (HWT). ZnO nanorods-hourglass-like, nanosheet-leafs-like and nanorods-oval-like were obtained with different HWT time.

Abstract: Zinc Oxide (ZnO) is well known for its wide band gap semiconductor with large excitation energy that serves various application. These unique characteristics had gained much research attention on ZnO nanostructure synthesis and physical properties. In this study, ZnO thin films were deposited on ITO/PET substrate by a spin coating sol-gel process. The starting solution were prepare by dissolved zinc acetate dehydrate (ZnAc) and diethanolamine (DEA) in water (H₂O) and 2-propanol (2-PrOH). Acid Citric (C₆H₈O₇) from 0.2 to 1.0 M were dropped into 100 ml sol-gel solution to study effect of sol-gel environment condition. ZnO thin films were obtained after pre-heating the spin coated thin films at 100 °C for 5 minutes after each coating. The coated substrates were undergone for Hot Water Treatment (HWT) process at 90 °C for 6 hours to grow ZnO nanostructures. The effects of sol-gel environment condition by drop different concentrations of C₆H₈O₇ into the solution were studied. Nanoflakes ZnO were obtained after hot water and hydrothermal treated at 90 °C for 6 hours with 0.2 till 1.0 concentration of C₆H₈O₇ dropped directly in the sol-gel solution. On the basis of the changes in morphology and microstructure induced by hot water treatment, it is concluded that the nanosheets were highly transparent with the visible range (350 – 800 nm) with 70%-90% of Transmittance spectra. Growth of ZnO nanosheet influenced by increment of C₆H₈O₇ mol concentration also with value of roughness RMS.

Abstract: Zinc Oxide (ZnO) known as wide band gap semiconductor with large excitation energy 60 meV, noncentral symmetry, piezoelectric and biocompatible for biomedical application are the unique characteristic that attract many researcher’s attention on ZnO nanostructure synthesis and physical properties. ZnO thin films were deposited on Si Glass substrate by a sol-gel process. The starting solution were prepare by dissolved zinc acetate dehydrate (ZnAc) and diethanolamine (DEA) in water (H₂O) and 2-propanol (2-PrOH). 0 to 60 drops of NaOH were dropped into 100 ml sol-gel solution to study effect of sol-gel modification. ZnO thin films were obtained after preheating the spin coated thin films at 100 °C for 10 minutes after each coating. The coated substrates were undergone for Hot Water Treatment (HWT) process at 90 °C for 6 hours to grow ZnO nanostructures. The effects of sol-gel modification by drop of NaOH into the solution were studied. ZnO nanorods and nanoflakes were obtained after hot water treated at 90 °C for 6 hours with different amount of NaOH dropped directly in the sol-gel solution. On the basis of the changes in morphology and microstructure induced by hot water treatment, it is concluded that the amount of NaOH dropped into sol-gel effected morphology of ZnO growth.

Abstract: The effects of surface oxidation of etched metallic Zn foils by hot water treatment for variable times and temperature investigated. ZnO nanostructures were obtained after undergoing hot water treatment at 50°C and 90°C for 2 to 24 hours. The SEM morphology showed ZnO nanostar-like and nanoneedle-like were observed with different hot water treatment temperature. XRD analysis confirmed the existing of ZnO nanostar-like and nanoneedle-like in a hexagonal wurzite structure. Growth of peak on (002) direction confirmed ZnO crystals are columnar in shape and anisotropic with wurzite structure oriented along c-axis. On the basis of the changes in morphology and microstructure induced by hot water treatment, it is concluded that the formation of ZnO are promising at low temperature.

Abstract: TiO₂/SiO₂ composite films were prepared by treating the sol-gel derived films with hot water. Amorphous silica was used as a binder with the aim of producing Si-O-Ti bonds. This process was done at 90°C under atmospheric pressure, and thus anatase nanocrystals-dispersed films can be formed on various kinds of substrates including organic polymers with poor heat resistance. The formation of anatase nanocrystals was found to proceed to hydrolysis of Si-O-Ti bonds. The crystalline phase, structure, morphology and photocatalytic performance of the films have been investigated.

Abstract: In order to learn effective methods for oleocellosis control, the induction of disease resistance and reactive oxygen species metabolism in valencia oranges by postahrvest polyamines treatment was investigated in this study. As showed in the result, polyamines and polyamine with hot water treatment had a significant effect on controlling oleocellosis during storage. Compared with control, MDA content in polyamine-treated fruit was rapidly decreased, but catalase and peroxidase activity had a sudden increase. Moreover, fruit in polyamines and polyamines with HWT treatment had a rapid increase in ASA-GSH anti-oxidation ability, and total phenols content in treated fruit also increased suddenly before 9 d, then followed by a sudden decline. Fruit in polyamines and polyamine with HWT treatment had a lower polyphenoloxidase (PPO) activity. Thus, polyamines may enhance antioxidation of citrus peel to improve disease resistance and decrease PPO activity to produce little rind spot during storage.

Abstract: Photocatalytic titania coatings loaded with palladium catalyst were prepared onto soda-lime glass substrates by using a low temperature synthesis for application of optical hydrogen gas sensor. Titania coatings were formed on the glass substrate by a sol-gel spin-coating process followed by a hot water treatment at 55°C. Metallic palladium nanoparticles were deposited onto the titania coatings, which obtained with addition of poly(ethylene glycol) (PEG) and without PEG after the hot water treatment, by means of a photodeposition technique at room temperature using UV-light irradiation. The whole fabrication process was carried out under atmospheric pressure. The Pd-photodeposited titania coating obtained with addition of PEG after hot water treatment showed higher hydrogen sensing properties than that obtained without PEG.

Abstract: Palladium (Pd) nanoparticles were prepared on photocatalytic TiO2-coated glass substrate by a photodeposition process and the optical hydrogen sensing properties were examined at room temperature. The TiO2 coatings were prepared on a non-alkaline glass substrate by a sol-gel process and hot water treatment. Pd nanoparticles were deposited on the TiO2 film by photodeposition using UV light. The obtained Pd/TiO2 thin film showed remarkable optical transmittance response to hydrogen gas at room temperature. The normalized transmittance of the Pd/TiO2 thin film at a wavelength of 640 nm decreased to 0.9 on exposing the film to hydrogen gas for only 5 s. This transmittance decrease is considered to be due to a gaschromic effect of the TiO2 photocatalytic coating.

Abstract: Zn-Al layered double hydroxide (LDH) thin films intercalated with various organic anions were prepared by immersion of sol-gel derived amorphous Al2O3-ZnO thin films in hot water containing organic salts like sodium dodecyl sulfate (SDS), sodium p-toluenesulfonate, and benzenecarboxylates. In all the systems, extended interlayer spacing of the Zn-Al LDH was observed after immersion in distilled water with the organic salts in comparison to the LDH with carbonate anions, indicating that we have succeeded in direct formation of Zn-Al LDH films with various organic anions on the substrates. It is suggested that divalent anions such as terephthalate ion have higher selectivity than monovalent anions.