Apiluck Eiad-Ua

Sensitivity Enhancement of Benzene Sensor Using Ethyl Cellulose-Coated Surface-Functionalized Carbon Nanotubes

A hybrid sensor based on the integration of functionalized multiwalled carbon nanotubes (MWCNTs) with ethyl cellulose (EC) was fabricated for sensitivity enhancement of benzene detection. To functionalize the surface of MWCNTs, MWCNTs were treated with hydrochloric acid for 60 min (A60-MWCNTs), while other MWCNTs were treated with oxygen plasma for 30, 60, 90, and 120 min (P30-MWCNTs, P60-MWCNTs, P90-MWCNTs, and P120-MWCNTs, resp.). Pristine MWCNTs, A-MWCNTs, and P-MWCNTs were dispersed in 1,2-dichloroethane, then dropped onto a printed circuit board consisting of Cu/Au electrodes used as the sensor platform. Next, EC was separately spin coated on the pristine MWCNTs, A-MWCNTs, and P-MWCNTs (EC/MWCNTs, EC/A-MWCNTs, and EC/P-MWCNTs, resp.). All sensors responded to benzene vapor at room temperature by increasing their electrical resistance which was sensitive to benzene vapor. The EC/P90-MWCNTs enabled an approximately 11-fold improvement in benzene detection compared to EC/MWCNTs. The sensitivity of all sensors would be attributed to the swelling of EC, resulting in the loosening of the MWCNT network after benzene vapor exposure. The differences of the sensing responses of the EC/MWCNTs, EC/A-MWCNTs, and EC/P-MWCNTs would be ascribed to the differences in crystallinity and functionalization of MWCNT sidewalls, suggesting that acid and oxygen plasma treatments of MWCNTs would be promising techniques for the improvement of benzene detection.

Influence of Temperature and Alkaline Activation for Synthesis Zeolite A from Natural Kaolin

Zeolite A from natural kaolin have been successfully synthesized via calcination and hydrothermal. However, these techniques have one drawback since, the impurities in kaolin such as muscovite and quartz in the kaolin structure, which depend on temperature and alkaline activation. This work was separated into two steps, first step was used calcination technique, and second step was used hydrothermal technique. Reaction of temperature in the first step was studied the influence of temperature from 500°C to 800°C for 3 hours. In this step, kaolin transformed to metakaolin and remain the impurities. Next, reaction of alkaline activation in second step was studied about the influence of NaOH. The concentration of NaOH in hydrothermal was varied from 1M to 4M and mixed with metakaolin at 90°C for 72 hours. X-ray Diffraction Spectroscopy (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) were used for characterization. The solid products were formed to zeolite A at 1M NaOH hydrothermal with 500°C to 800°C calcination and it can be seemed good of euhedral structure at 700°C

The Effect of Calcium-Based Salt on Hydrothermal Carbonization of Corncob

Corncob represents a great potential as a raw material for the production of high-value added chemicals, fuels and other industrial products. Thus, corncob is suitable residue for study molecular structure through the pretreatment method. In this study, the effect of calcium-based salts on the hydrothermal carbonization (HTC) of corncob were studied at 160, 180, and 200 °C for 2 h. CaSO4 and Ca3(PO4)2 were used as a reaction medium. Hydrochar was characterized by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and ATR-Fourier transform infrared spectroscopy (ATR-FTIR). Characteristics of the hydrochar varied with calcium-based salt. Cellulose crystallinity in hydrochar decreased dramatically and carbon content in hydrochar obviously increased when Ca3(PO4)2 and CaSO4 were added, respectively. In case of hydrothermal at 180°C with Ca3(PO4)2 and CaSO4, the carbon microsphere was occurred.

Synthesis of Carbon Nanoparticles from Used Motor Oil and Benzene via Solution Plasma Process

Carbon nanoparticles (CNPs) were successfully synthesized from the mixture of used motor oil and benzene via a solution plasma process (SPP). The synthesis was achieved within a single step at room temperature and atmospheric pressure. The effects of mixing ratio between used motor oil and benzene on the physical and chemical properties of CNPs were investigated by means of field-emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Raman spectroscopy. The results revealed that there were no significant changes in morphological feature and chemical functional groups on CNPs at different mixing ratios. The CNPs exhibited the aggregates of fine particles with the diameter of about 20–30 nm. The crystallinity of CNPs was found to be slightly increase when synthesized under the presence of used motor oil, possibly due to the effect of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons in used motor oil. We expect that the conversion of used motor oil into CNPs by SPP could be another attractive way to add the value to used motor oil prior to disposing.

Fabrication of Low Cost Membrane from Anodic Aluminum Oxide

Anodic Aluminum Oxide (AAO) membrane has been successfully fabricated from two-step anodization with aluminum low grade (Al6061). The pore density, the pore diameter, and the interpore distance can be controlled by varying anodization process conditions. However, there are limits to control the mechanical strength and growth of AAO arrays, such as pore density, pore diameter and interpore distance. In this research the self-organized two-step anodization is carried out varying time at 24, 48 and 72 hours, respectively with 40V at the low temperature 2-5°C. The optimum conditions of AAO with two-step anodization is 40V for 48 hr. Finally, AAO substrate is separated from aluminum low-grade and enlarged pore diameter with pore widening process by 5% H3PO4. The physical properties were investigated by mean of field emission scanning electron microscope (FE-SEM) show that the average pore diameter and average interpore distance increase with the anodization time. Al6061 Aluminum substrate can be used to fabricate a nanoporous AAO film with an average pore diameter and average interpore distance larger than 70 and 90 nanometers, respectively but less mechanical stability.

Production of γ-Valerolactone from Methyl Levulinate via Catalytic Transfer Hydrogenation on Nickel-Copper Oxide Catalyst

γ-Valerolactone (GVL) is successfully produced via catalytic transfer hydrogenation from methyl levulinate on nickel copper oxide catalysts with the comparable result to that of Raney-nickel. This catalyst is prepared at lower temperature (lower than 1000oC) and pretreatment is not required before its use. Among different calcination temperature, Ni-Cu-O which synthesis at 700oC shows the best catalytic performance with 100% methyl levulinate conversion and more than 95% GVL yield and characterization result was shows this calcination temperature was affect catalyst to highest crystallization and surface area. The study of atomic ratio effect indicates that nickel-copper oxide which had nickel oxide more than copper oxide is better for this reaction.

Effect of Anodizing Voltage on Anodic Titanium Dioxide (ATO) Growth Based on an Ethylene Glycol Solution Containing NH4F

We reported on the influence of applied voltage on the surface morphology of anodic titanium dioxide (ATO) thin films. At first, titanium (Ti) thin films were prepared by DC-magnetron sputtering for use as a base material in the anodization process. The titanium dioxide (TiO2) nanoporous ATO was fabricated by the anodization process from the Ti thin film, with different applied voltages from 20 V to 60 V in an electrolyte based on an ethylene glycol containing NH4F. Pore size distribution of ATO thin films can be varied from 20-50 nm by increasing the applied voltage, while the thickness of the film also increases. In addition, to observe the effect of time, the optimal condition of anodizing voltage was studied by increasing the anodizing time. The results clearly showed the nanoporous ATO over the films and the thickness of the nanoporous ATO is approximately 260 nm.

Effect of Alkaline Activation on Low Grade Natural Kaolin for Synthesis of Zeolite A

The conventional technique to synthesizes zeolite A from kaolin is calcination. However, this technique has one drawback since, the impurities in kaolin, such as muscovite and quartz, remain. Therefore, the hydrothermal process without calcination is used to synthesize high purity zeolite A. Hydrothermal synthesis without calcination can be separated into two steps, namely first and second hydrothermal steps. Alkaline activation reaction in the first hydrothermal step was used to study the effect of NaOH concentration ranging from 4M, 6M, 8M, 10M to 12M at 200°C for 3 hours. In this step, sodium aluminosilicate (cancrinite and nepheline hydrate) was produced and then dissolved in HCl. After filtration, the impurity was removed, and adjusted for neutral pH of 7 to form amorphous aluminosilicate gel. For the second hydrothermal step, amorphous gel was mixed with NaOH (1-4M) to form zeolite A at 90°C for 3 days. The x-ray diffraction (XRD) and Scanning Electron Microscope (SEM) were used for characterization.

Fantastic Carbon Material for Nickel/Carbon Support Catalyst Reducing via Calcination Enhanced with Hydrothermal Carbonization

In generally, the metal catalyst which synthesis by conventional techniques is usually in metal oxide form or easily oxidize in the air thus the metal catalyst must reduce to metallic form before using. It was complex process and dangerous. In the research, Carbon material from cattail flower (CF) were used as supporter of Nickel/Carbon supported metal catalyst (Ni/C). This research were studied effect of used carbon material from CF as supporter of Ni/C and varying nickel loading. The Ni/C catalyst were prepared by hydrothermal, impregnation and calcination process. Firstly, Dried CF has been pretreat via hydrothermal process with optimized condition at 180°C for 8h. Then, the nickel solution was added to support via impregnation method by varying Ni loading from 20 to 60 wt% of supported. Finally, the sample has been pelleted into 0.5mm-Ni/C pellet and calcined at 900°C for 2h under nitrogen atmosphere. Ni/C were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), surface area and pore size distribution was determined by N2 adsorption. The result indicate that nickel particle on Ni/C were in the free metal from without reduction and well dispersed on supported surface. Particle size and surface area of Ni/C were decreases at the increase metal loading. Nickel/Carbon supported metal catalyst were ready to use and could be controlled particle size, surface area and crystallinity by metal loading.

Synthesis of Carbon-Supported Metal Catalysts by HTC and Electroplating Processes from Cattail Flower

Carbon-supported metal (nickel) catalysts has been synthesized from Cattail flower (CF) by two stage processes: hydrothermal carbonization (HTC) and electroplating technique. In the first stage, CF has been transformed in the HTC process with optimized condition at 180°C for 8h. Then the samples have been compressed into the 5 mm-pellet and calcined under nitrogen atmosphere at 900°C for 2 h to active-surface carbon which produced high surface area and good conductivity. In the second stage, the products obtained from HTC were subjected to produce the carbon-supported metal catalysts. Due to the good electrical conductivity of the carbon from HTC process, the metal can be effectively deposited on the carbon surface. Various parameters such as temperature of solution (40-60°C) and voltage (3.0-5.0V) have been studied. The results indicated that the electroplating process of solution temperature 50°C under applied voltages at 4.0V were the optimal conditions produced to mostly metallic phase.