Advanced Materials Research Vol. 1024

Abstract: Incorporation of iron oxide nanoparticles into Poly(diallydimethylammonium chloride) coated silica colloids is developed to produce novel nanocomposite. The structure is synthesized via layer-by-layer assembly with the entire process driven by electrostatic interaction. Dynamic light scattering and zeta potential measurements are employed to monitor the evolution of the nanocomposite from its constituent materials to full development of final structure. Morphology of the as-synthesized nanocomposite is observed by transmission electron microscopy. The magnetic responsiveness under low magnetic field gradient enables the aforementioned nanocomposite to be recovered for recycle purpose. The engineering application of this material is tested by taking Methylene Blue and Remazol Brilliant Blue R dyes as model system. The study reveals the efficiency and activity of the nanocomposite for dye removal during four consecutive runs.

Abstract: Morphological evolution and phase transformations of copper ion doped TiO₂nanotubes after being calcined at different temperatures were studied by field emission scanning electronmicroscopy, transmission electron microscopy, and X-ray diffraction. After calcination at 300°C, the nanotubes with uniform diameter and length wereobtained. At 400°C, the nanotube structures were maintained. Nevertheless the inner tube diameter became narrower, and in same instances disappeared due to aggregation of nanotubes. The copper ion doped TiO₂nanotubes then transformed to nanorodsat 500°C and the length of the nanorodsshortens after calcination at 600 °C. When the calcination temperature was further increased to 700°C, the nanorodsdisintegrate to form nanoparticles. On the other hand the phase structures of copper ion doped TiO₂ nanotubes calcined at 300 and 400 °C were TiO₂ hexagonal. After calcined at higher temperature (600 and 700°C) they transformed to anatase TiO₂ (tetragonal).

Abstract: The effluent of wastewater treatment plants (WWTPs) is an important source of priority substances and is, therefore, one of the bottlenecks in achieving the European Water Framework Directive (WFD) objectives. At various locations in the Netherlands, standard for priority substances are exceeded. The current concern regarding the cost and treatment method of these micropollutants in receiving waters may call for new approaches in wastewater treatment. In this study, a new treatment alternative is developed to remove micropollutant and wastewater parameter effectively and in a more cost effective way. A potential solution is the used of clay coupled with biodegradable polymer flocculants. Clay is naturally abundant and relatively inexpensive compared to currently conventional used adsorbent which can also act as coagulants. Experimental studies were carried out with four different nanoclay to select the best nanoclay for further optimisation. The atrazine removal percentage archived is in the range of 10-99% based on the nanoclay concentration of 0.01-50 g/L. Optimisation of best nanoclay performer leads towards atrazine reduction of >99% with dosage of 0.1 g/L. The best and underperformed nanoclay then tested in other experiments with the addition of cationic starch flocculants. In this experiment, the addition of polymer increased the atrazine removal for the underperformer nanoclay to 46% with only 0.01 g/L clay dosages. This new approach in dealing with both micropollutant and wastewater parameter is promising and might help in reducing the compound concentration and the operational cost. However, further analysis and optimisation is required before any conclusion can be made.

Abstract: Nanosized Bismuth Iron Garnet (BIG) was synthesized via sol-gel method. The nanomaterials with ferrite structure were heat-treated at different temperatures from 700 to 1100 °C. The structure and morphology were characterized by Powder X-ray diffraction (PXRD) and Scanning electron microscope (SEM), respectively. The PXRD show that with the increase of temperature the size of crystallites for BIG gradually increased. The BIG ferrite nanopowder was composited with polyvinylidene fluoride (PVDF) by solution casting method with different ferrite ratios. The magnitudes of S-parameters of PVDF/BIG were investigated using rectangular waveguide in conjunction with a microwave vector network analyzer (VNA) at microwave frequencies. The S-parameters of PVDF/BIG are found to be slightly different from those of ferrite contents in polymer composites. The S₁₁ is found to be increased by increasing the ferrite content of the composites as well as with frequency while the S₂₁ is observed to decrease with increase in ferrite content.

Abstract: A low temperature sol-gel approach was demonstrated to prepare ZnO nanoparticles with controlled morphologies. By changing the concentration of NH₄OH, the ZnO nanoparticles evolves from sphere-like, star-like and sheet-like structures. No peak of additional phase was observed in the XRD patterns except the diffraction peaks of ZnO. The estimated crystallite size of ZnO nanoparticles decreases with the increase of NH₄OH. It is also found that the morphology of nanoparticles affects the optical bandgap of ZnO. The optical bandgap of sphere-like,star-like, and sheet-like ZnO nanoparticles are 3.55 eV, 3.48 eV and 3.45 eV, respectively. The growth mechanism of ZnO nanoparticles was discussed.

Abstract: It is difficult to produce a good film consisted of nanocrystals with good alignment. So far, a lot of methods and especially expensive vacuum-based methods have been used to produce such films. In this paper, sol gel and spin coating method were introduced. The combination of these simple and cheaper methods was used because of the high potential of those methods to produce good quality nanocrystals. First, nanocrystals were produced by sol gel method and later spin coating was done to control the thickness of the nanocrystals film. During the spin coating process, a metal tape was used to avoid solution from splashing out from the glass substrate. Subsequently, nanocrystals film was heated up from room temperature to 400 °C. To study the alignment of nanocrystals, Field Emission Scanning Electron Microscopy (FE-SEM) was used. Through this analysis, we found that the nanocrystals was in spherical pattern and the alignment of this film was well arrayed. Here, the combination of the two cheaper and simpler methods can be used to produce good quality of nanocrystals thin film and at the same time can save our research cost.

Abstract: Abstract: Thin anodic alumina (AAO) templates with uniform nanoscale pore diameters and interpore distances were fabricated by a two-step anodization technique on a Si-based (AAO/Ti/Si structure) under controllable anodizing conditions. The obtained thin AAO templates were approximately 60 nm in pore diameter and 1.2 µm in length with 110 nm interpore distances in area of 1 cm². A bottom barrier layer of the anodic alumina (AAO) templates was removed by a wet etching using phosphoric acid (5 wt%) under control of etching time. As an application, Cu nanorods arrays embedded in anodic alumina (AAO) template were fabricated by electrodeposition. The morphologies and structure of the templates and the Cu nanorods produced were analyzed using Field-emission scanning electron microscope (FESEM), Energy dispersive x-ray spectroscopy (EDX) and X-ray diffraction (XRD).

Abstract: In this work, 12 μm titanium oxide (TiO₂) nanotube arrays were formed by the anodization of titanium (Ti) foil in ethylene glycol containing 1 wt% water and 5 wt% fluoride for 60 min at 60 V. After annealing at 400 °C in argon for 4 hr, TiO₂ nanotube arrays were immersed in 0.02 M phosphoric acid (H₃PO₄) to incorporate phosphorus (P) into TiO₂ nanotube arrays. Results from x-ray photoelectron spectra revealed that the P-incorporated TiO₂ nanotubes contained Ti, oxygen (O), P and carbon (C) after wet impregnation process. The photocatalytic activity of the nanotube arrays immersed in H₃PO₄ at various impregnation times was evaluated by monitoring the degradation of methyl orange. Results indicate that the nanotube immersed in H₃PO₄ for 90 minutes with an average diameter of 100 nm and an optimal tube length of 12 μm with a thin tube wall (20 nm) is the optimum structure required to achieve high photocatalytic reaction. The incorporated C and P into TiO₂ nanotube arrays is believed to provide a shallow trap for photo-generated e^- and h⁺, inhibiting the recombination and extending the lifetime of the charge carriers. Thus, this sample resulted in high degradation of methyl orange as compared with other samples. In addition, the existence of C, P, and high degree of anatase crystallinity, smooth wall and absence of fluoride enhanced the photocatalytic activity of the sample.

Abstract: Carbon dioxide (CO2) is considered to be the main greenhouse gas contributing to global warming and climate change. Therefore, the present paper investigates the CO2-capture performance of synthesized calcium hydroxides, Ca(OH)2 sorbent at different temperatures which are 350, 450, 550 and 650°C. The CO2 adsorption of the materials synthesized was studied in a thermo-gravimetric analyzer (TGA). The CO2 adsorption temperature strongly influenced the capture performance of the absorbent. The Ca(OH)2 sorbent are prepared by hydrolysis of calcium alkoxides, NaOH as precipitating agent and mixed solvent of ethanol with deionized (DI) water as medium at 35°C. X- ray diffraction (XRD) result showed 40 nm crystallite size of Ca(OH)2 hexagonal crystal structures. The Ca(OH)2 particle size and morphological properties before and after CO2 adsorption are studied by Field Emission Scanning Electron Microscopy (FESEM). The FESEM image indeed showed the rod like shape of Ca(OH)2 structures with rod length increased from 765 to 893 nm while the diameter is between 140 to 160 nm. When Ca(OH)2 sorbent adsorbed CO2, the structures are rigid interconnected each others like a lump shaped. The prepared Ca(OH)2 sorbent possesses a great potential to capture CO2 when increased temperature. Nevertheless, at intermediate temperatures (350-450°C), Ca(OH)2 sorbent still demonstrates a higher CO2 capture capacity than other intermediate temperature adsorbents such as layered double hydroxides (LDHs), lithium zirconates (LiZrO3) and hydrotalcites.