Wipada Sanongraj

Mathematical Model for Photocatalytic Destruction of Organic Contaminants in Air

Abstract Photocatalytic oxidation (PCO) was investigated in a bench-scale reactor for the abatement of two airborne organic contaminants: toluene and ethanol. A mathematical model that includes the impacts of light intensity, initial contaminant concentration, catalyst thickness, and relative humidity (RH) on the degradation of organic contaminants in a photocatalytic reactor was developed to describe this process. The commercially available catalyst Degussa-PtTiO2 was selected to compare with the MTU-PtTiO2-350 catalyst, which was synthesized by the sol-gel process, platinized, and calcined at 350 °C. For toluene removal using the MTU-PtTiO2-350 catalyst, the degradation rate increased with increases in light intensity from 0.2 to 2.2 mW/cm2 and in catalyst thickness from 0.00037 to 0.00361 cm. However, further increases in light intensity and catalyst thickness had only slight effect on the toluene degradation rate. Increasing the initial concentration from 6.29 to 127.9 μg/L and the RH from 10 to 85% resulted in decreases in the toluene degradation rate. For ethanol removal using the MTU-PtTiO2- 350 catalyst, the degradation rate increased more rapidly with an increase in RH from 17 to 56%; the RH had little effect on the ethanol degradation rate while it further increased from 56% to 82%. We discuss applicability of the model to estimate the influence of process variables and to evaluate photocatalyst performance.

Characteristics of Bacterial Cellulose Production from Agricultural Wastes

There are increasing demands to substitute the plastic from the petrochemical industry with bacterial cellulose which were produced from microorganisms as Acetobactor xylinum strain. The aim of this study was to produce bacterial cellulose from banana peels which are agricultural waste around Walailak University area. The banana peels were used as a carbon source together with nutrient medium for the growth of bacteria. The ratio between Hestrin and Schramm nutrient medium (HS) with banana peel to DI water was 1:0.5, 1:1, and 1:1.5 (%V/V). Sugar content in banana peel (control) was 4.0% Degree Brix. The initial pH was 6.0 and sugar contents varied in this study were 5.5%, and 11% Degree Brix. A.xylinum dosages used in the cultivation were 5, 6.67, and 8.33 (%V/V) respectively. The cultivation times were 15 days at the temperature of 30 °C. As a result, the highest yield of produced bacterial cellulose was 19.46 gram and the best condition which maximum yield of bacterial cellulose 1.95% can be obtained was 11% (Brix) of sugar content, 6.67 (%V/V) of A.xylinum added, and 1:1.5 of banana peel to DI water. The physical properties of bacterial cellulose were studied with ATR-FTIR spectroscopy which shown adsorption spectrum at 3279, 2915, 1627 and 1013 cm-1 corresponding to the-OH,-CH,-CH2 and carboxyl function groups, respectively. Glass transition Temperature (Tg) was 116.85°C. Tensile strength was measured with UTM and had average value of 41.13±5.43 Mpa. The bacterial cellulose had moisture content of 90.00±0.02%. The synthesized bacterial cellulose can be used as adsorption media and also has its chemical properties like petroleum polymer. Result suggested that the similar property can be observed when compared with petroleum plastic, however with the exception of methyl group (CH3). Methyl group which can be found in plastic synthesized from petrochemical is responsible for the strength of plastic. Thus, bacterial cellulose, synthesized in this study, is not as strong as petrochemical plastic. But it can be used to produce bio-plastics because of the-CH and-CH2 functional group attached. With the similar physical and chemical properties to those of petrochemical plastic, bacterial cellulose can be used as biopolymer.

The Synthesis of Air Filters from Silk Cocoons Coated TiO2 for Use in Air Purifier

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 PM2.5. 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 PM2.5 concentration was 5 mg/m3, air flow rate was 3.93 m3/min. Treatment period was 8 hours.

Preparation and Characterization of the TiO2 Coated Silk Fibroin Filters

The main objectives of this research are the synthesis and characterization of the TiO2 coated silk fiborin filters for indoor air contaminant removal. Silk fibroin was degummed from silk sericin using sunlight soap solutions at 90 °C for 60 mins. Next it was washed with distilled water, reformed into a rectangle shape, and dried at 80 °C for 3 hrs in a vacuum oven. Silk fibroin filters were then coated with TiO2 solution at different dosages and dried in sunlight. Morphological structure of the TiO2 coated silk fiborin filters was analyzed using a scanning electron microscope (SEM). The band gap energies of the filters were measured using a UV/VIS/NIR spectrophotometer. Pressure drop across the filters was also examined using the manometer technique. SEM micrographs revealed the fibrous morphology of the SF fiber. An average diameter of the SF fiber was estimated to be approximately 10 μm. The spectral data recorded from the UV/VIS spectrophotometer showed the strong cut off at 390 nm. Therefore, the band gap engergy can be caculated to be approximately 3.17 eV. From the pressure drop testing, differential pressure of the filters without TiO2 was very small, and it was relatively increased with percent TiO2 coated on the SF filters. However, the differential pressures of the SF filter are less than that of the commercial air filter. The VOCs removal efficiency of the synthesized filters will be further investigated.

Improvement of TiO2/LDPE Composite Films for Photocatalytic Oxidation of Acetone

Titanium dioxide with coupling agent (ETES) was applied as a photocatalyst for a synthesis of the TiO2/LDPE composite film. The physical properties of TiO2/LDPE composite film were analyzed by a Scanning Electron Microscope (SEM). TiO2 particles were impregnated into the polymer matrix film as a LDPE composite film. The results from the X-ray Diffraction (XRD) technique revealed that the structure of TiO2/LDPE composite film were anatase crystalline. The chemical structure of the TiO2/ LDPE composite films were analyzed by an ATR-Fourier transforms infrared (ATR-FTIR) spectrometer. Wavenumber of FTIR spectra at 719 cm1 indicated the Ti-O-Ti bond. Band gap energies of the films ranged from 3.19-3.29 eV. The photocatalytic activity of the film was tested for removal of gaseous acetone in a closed chamber. Experimental conditions were set as follows: a UV light intensity of approximately 2.7 mW.cm-2, flow rate of 2 L.min-1, and an initial acetone concentration of about 435±20 ppm. While the catalyst dosage was varied from 3% to 15% (wt. cat/wt. film).The degradation rate of acetone increased when increasing dosage of TiO2 from 3% to 10%, then decreased a little bit when increasing the dosage to 15%. The TiO2/LDPE composite film at the dosage of 10% yielded the highest removal efficiency of 75%, followed by the film at the dosage of 15%, 5%, and 3%, respectively.

Quantity of Formaldehyde in Particleboards

The objective of this study was to determine formaldehyde emission considering the following factors; indoor air temperature, type of resin, and thickness of particleboard. Formaldehyde emissions from particleboards were analyzed using the JIS A 1460 and the Perforatored EN 120 methods. Three sets of experiments were conducted to investigate effects on formaldehyde emission from particleboard samples due to these factors. For the first factor, test specimens were conditioned in a dry oven at 20, 35, and 40 °C for a period of 1, 2, 3, 5, and 7 days, emission were analyzed using the JIS A 1460 method. The second factor, type of resin, formaldehyde emissions and remaining were analyzed by the JIS A 1469 and the Perforatored EN 120 methods. For the third factor, thickness of particle board, samples with different thickness were used in the experiments. Results of the first factor indicated that the highest formaldehyde emission was obtained at the condition temperature of 20 °C followed by the emissions at the condition temperature of 35 °C and 40 °C, respectively. In addition, formaldehyde emissions decreased as the condition time increased. Results of the second factor showed that for the JIS A 1469 method, particleboards made with the 10L617A (UF:E1) resin emitted the lowest amount of formaldehyde. While particleboards made with the 10L631 (MUF:E2) resin emitted the lower amount of formaldehyde as compared to the particleboards made with the 10L686 (UF:E2) resin. For the Perforatored EN 120 method, formaldehyde remaining in samples made with UF:E0 was lowest followed by samples made with UF:E1 and UF:E2, respectively. Results for the third factor indicated that the thickness of particleboard has no significant effect on formaldehyde emission. This effect was found for both methods of analysis.

Turbidity Removl Using Silk Sericin and Silk Sericin Powder as Coagulant Aid

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