Advanced Materials Research Vols. 931-932

Abstract: Direct contact membrane distillation (DCMD) process was applied for brine solution recovery. The energy consumption of the process was evaluated as varying feed temperature and cross flow velocity (CFV). The evaporation efficiency and energy consumption were also studied. The experiments was carried out using a hollow fiber PVDF membrane with pore size of 0.1 μm and NaCl 3.5 %wt as feed solution. The operating feed temperature and CFV were in range of 40 °C-70 °C and 0.14-0.42 m/s (laminar and transition flow region), respectively. The temperature and CFV of permeate were fixed at 20 °C and 1.97 m/s respectively. It was found that the flux rate was in function with the temperature, CFV and temperature polarization coefficient (TPC). The best result in terms of energy consumption and evaporation efficiency were obtained at CFV and temperature of 0.28 m/s and 70 °C about 188.6 W and 41.1 %, respectively.

Abstract: Removal of azo dye (Novacron Orange C-3R) in water using vacuum ultraviolet (VUV) process was investigated. The factors affecting the VUV process included concentration of dye, power of VUV and bicarbonate (HCO₃^-) were studies. Ultraviolet (UV) experiment was also performed for comparison. Initial dye concentrations of 5, 10, and 50 mg/L, VUV powers of 30, 60, and 120 W and bicarbonate 450 and 900 mg/L as CaCO₃ were tested. At lamp power of 120 W, VUV process could be reduced 99.85 % of dye and 99% of chemical oxygen demand (COD) while UV process reduced 44.69 % of dye, 50% of COD. Bicarbonate was found to have little impact on dye removal rate.

Abstract: This work reports the fabrication and photoelectrochemical response of titanium dioxide (TiO₂) nanofiber photoelectrode prepared by an electrospinning technique. Transmission electron microscopy (TEM) images reveal that the electropun nanofibers are composed of TiO₂ nanoparticles with the average diameter size of 25 nm. The scanning electron microscopy (SEM) image of the photoelectrode confirms the existence of TiO₂ nanofiber networks on Ti/Si substrate after the electrode preparation using a doctor-blade technique. The photoelectrochemical performance of TiO₂ nanofiber electrode is investigated in comparison with that of TiO₂ (Aeroxide P25) nanoparticle electrode. When the TiO₂ electrodes are subjected to light illumination at 100 mW/cm², the maximum photoconversion efficiency (PCE) of 0.95% is obtained at the TiO₂ nanofiber electrode while reduced PCE of 0.75% is obtained at the TiO₂ nanoparticle electrode.

Abstract: The L1₀-FePt/Fe based exchange coupled composite (ECC) bilayer media is one candidate to extend the areal density of magnetic recording system and solve writability issue in trilemma. L1₀-FePt is the great high magnetic anisotropy material. Therefore, the magnetic parameters of this material such as magnetocrystalline anisotropy constant, K_u, saturation magnetization, M_s, and exchange coupling between a soft/hard interface, are important on magnetic material properties. In this work, the effects of magnetic parameters on magnetic properties of L1₀-FePt/Fe based ECC bilayer media are simulated by the object oriented micromagnetic framework based on Landau-Lifshitz-Gilbert equation. The ECC bilayer media can reduce switching field, H_sw, of media lower than available writing head field. Hence, writability issues of high K_u media can be achieved. Reducing H_sw of ECC bilayer media obtains from lower K_u and higher M_s values. This work can achieve writing capability of a future magnetic recording system.

Abstract: The main objective of this research is to synthesize silk sericin and silk sericin powder for turbidity removal of synthetic turbid water. Silk sericin used as coagulant aid in this study was extracted from silk cocoons by boiling them with 0.5% (w/w) Na₂CO₃ solution at 90°C for 60 min. Synthetic turbid water with the initial turbidity of about 50 NTU, 75 NTU, and 100 NTU, the turbidity removal efficiencies 89.2±5.41%, 90±3.48% and 87±4.31% respectively. For the powder silk sericin, the turbidity removal efficiencies 96±0.77%, 88±2%, and 96±1.73% respectively. Introduction

Abstract: The purpose of this research was to synthesize and form fibroin silk air filter (SF filter) coated and non-coated with titanium dioxide. For use in indoor air pollution treatment. The main air pollutant to be treated is PM_2.5. However, VOC removal also investigaed in this study. The synthesis involved degumming process using 0.5 wt % Na₂CO₃ at 90°C for 60 minutes. Titanium dioxide (TiO₂) used in the study was a catalyst Tipaque brand (code A-220 (Anatase)). Results from studying on physical property by scanning electron microscope found that silk fibre was an ununiformly arrangement structure. SF filter coated with TiO₂ showed that TiO₂ distributed uniformly on the filter. The silk fibroin filters were brought to analyze for the energy band gap in order to find the energy value that the catalyst was needed to stimuate reaction in the photocatalytic process. It was found that TiO₂ 1-7.5 %(w/v) catalyst coated on the silk fibroin filters had the highest value of light absorption at 390 nanometers, which agreed with the value of energy level in the band gap period of 3.18 eV.The results from efficiency studies of SF filters in the treatment of indoor air pollution (generated from incense fume of 0-2 micron in size) indicated that the best treatment efficiency was 99.76%. In which SF filter non-coated with TiO₂ was used, and initial PM_2.5 concentration was 5 mg/m³, air flow rate was 3.93 m³/min. Treatment period was 8 hours.

Abstract: The intention of this study was to prepare the environment friendly durian seed starch/polyvinyl alcohol (DSS/PVOH) composite hydrogels modified by chemical cross-linking with glutaraldehyde and to assess the adsorption potential of the DSS/PVOH composite hydrogels for the removal of the synthetic dyes from aqueous solution. The hydrogels were characterized by swelling behavior and scanning electron microscope (SEM). The effect of DSS content and initial dye solution pH on the adsorption capacity was studied conducting batch experiment system. The DSS/PVOH composite hydrogels consisting 3% DSS has optimum adsorption capacity of 3.411 mg/g (for methylene blue under the condition of pH 7) and 3.274 mg/g (for acid orange 8 under the condition of pH 2.5) at 24 h of contact time. The adsorptions were well fitted by the pseudo-second order kinetic model. It was indicated that the mechanism of removal predominant is effective for low dye concentrations, below 10 mg/l.

Abstract: Titanium dioxide (TiO₂) powder was prepared by hydrothermal route. Titanium isopropoxide, ammonium hydroxide and nitric acid were used as the starting materials. The final pH value of mixed solution was 1 and treated at 80 and 100 °C for 26h. The phase transition of TiO₂ powder was studied by Xray diffraction (XRD). Multiphase of anatase and rutile of TiO₂ powder were obtained at 80 and 100 °C for 26h without calcination steps. The morphology of TiO₂ powder was investigated by scanning electron microscopy (SEM). The particle was highly agglomerated and irregular in shape with the range of particle size of 0.10.3 μm. The chemical composition of TiO₂ powder was examined by energy dispersive spectroscopy (EDS). The element chemical compositions show the characteristic Xray energy level as follows: titanium K_α = 4.51 keV and K_β = 4.93 keV and oxygen K_α = 0.52 keV, respectively. The photocatalytic degradation efficiency of 2chlorophenol (2CP) over TiO₂ powder was determined by gas chromatography (GC). It was found that TiO₂ powder prepared by hydrothermal route at 80 °C for 2h was the best efficiency for photocatalytic degradation of 2CP.

Abstract: Cold and hot work tool steels AISI D2 and AISI H13, respectively, were borided using a packed boriding process. Boriding temperature range of 1123 1223 K was performed with different boriding time up to 6 hr, afterwards, near-surface properties of the borided tool steels AISI D2 and H13 were characterized. Boride layer thicknesses were measured using an optical microscope with an image analyzer program. An X-ray diffraction (XRD) was performed to identify the boride coating layer. Kinetics of boriding process was analyzed using diffusion and Arrhenius equations. Activation energies and empirical data of the boriding process can be finally determined. It was found that the thickness of the boride coating increases with increasing boriding temperature and time taking into account the diffusion and Arrhenius equations. Activation energies of 177.4 and 185.7 kJ/mol were determined for cold and hot work tool steels AISI D2 and AISI H13, respectively. Thus, empirical relationships of boride thickness as a function of boriding temperature and time will be presented. Finally, predicted boride thickness diagram of cold and hot work tool steels AISI D2 and AISI H13, respectively can be established.

Abstract: Bone grafting is the standard treatment for cleft palate patients. However, a downside to this method is that it requires multiple surgeries to fill the gap in the mouth. Bone tissue engineering can be employed as a solution to this problem to fabricate artificial bone based on synthetic biomaterials. The objectives of this study focus on preparing phosphate glass and hydroxyapatite (HA) as well as developing appropriate forming conditions for scaffold based on the polymeric replication method. Various glass compositions and sintering temperatures were examined in order to investigate scaffold structure, compressive strength, and biodegradability. Amounts of CaO and sintering temperatures were varied in order to explore their impacts on scaffold properties. Results from XRD clearly show that phosphate glass and HA can be successfully synthesized using natural materials. It was also found that polymeric foam replication can be successfully used for scaffold fabrication and the scaffold microstructure revealed that the appropriate pore size for bone tissue engineering is in the 240 360 μm range. Results indicate that biodegradability can be regulated by the amount of CaO used. For example, specimens with the highest level of biodegradability were obtained from 30 mol% of CaO composition. The highest compressive strength (6.54 MPa) was obtained from scaffold containing 40 mol% of CaO, sintered at 750 °C.