Ratchadaporn Puntharod

Preparation and Characterization of BiVO4 Powder by the Sol-gel Method

Bismuth vanadate (BiVO4) powder was successfully prepared by the sol-gel method. Bismuth nitrate and ammonium vanadate were used as the starting precursors with mole ratio of 1:1 in ethanol media at 70°C for 1 h. The yellow gel was calcined at 400–600°C for 2 h. The phase of BiVO4 powder was characterized by X-ray diffraction (XRD). The morphology and chemical composition of BiVO4 powder were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). The functional groups of BiVO4 powder was identified by Fourier transform infrared spectroscopy (FTIR) and the surface area of BiVO4 powder was determined by Brunauer, Emmett and Teller technique (BET).

Supramolecular interactions playing an integral role in the near-infrared Raman "excitonic" enhancement observed in β-hematin (malaria pigment) and other related heme derivatives.

To gain more understanding into the mechanism that enables the dramatic resonant Raman enhancement of totally symmetric modes observed in hemozoin (malaria pigment) and other related heme supramolecular arrays when applying near-infrared excitation wavelengths, the iron(III) porphyrins Fe(TPP)Cl, [Fe(TPP)](2)O, Fe(OEP)Cl, and [Fe(OEP)](2)O along with β-hematin (synthetic hemozoin or malaria pigment) were analyzed in the solid state using resonance Raman spectroscopy. The critical finding was that from the model compounds investigated, all except [Fe(OEP)](2)O exhibited the enhancement of the totally symmetric mode ν(4) when exciting the molecules with 782 and 830 nm laser lines. Through a detailed comparison of X-ray crystallographic structures, it is proposed that intermolecular noncovalent interactions play an integral role in enabling excitonic interactions to occur in these heme supramolecular systems. Comparison of the solid- and solution-phase electronic spectra in the near-IR region indicated more absorbance in the solid state between 800 and 900 nm. The electronic spectrum of [Fe(OEP)](2)O shows minimal absorbance in this region compared to that of the other compounds. All heme derivatives investigated have similar structure with a five-coordinate high-spin iron(III) ion. The crystallographic data indicate no significant differences in porphyrin geometry between TPP and OEP derivatives studied. However, [Fe(OEP)](2)O contains less supramolecular interactions in comparison to the other species. The supramolecular bonding enhances the probability of through-space interactions between the transition dipoles from electronic transitions of extended π systems. Our results indicate that the intensity of ν(4) is in part strongly affected by C-H···X hydrogen bonding interactions when X is an electron-donating entity. Such information may have important implications in the design and monitoring of antimalarial drugs that specifically interfere with hemozoin formation.

Characterization of bismuth vanadate (BiVO4) nanoparticle prepared by solvothermal method

ABSTRACT Bismuth vanadate (BiVO4) nanoparticle was prepared by solvothermal method. The starting precursors were used as bismuth nitrate pentahydrate (Bi(NO3)3•5H2O), ammonium metavanadate (NH4VO3) and absolute ethanol (C2H5OH). Solution I: Bi(NO3)3•5H2O was dissolved in 2.0 M nitric acid (HNO3) and absolute ethanol (C2H5OH). Solution II: NH4VO3 was dissolved in 2.0 M ammonium hydroxide (NH4OH) and absolute ethanol (C2H5OH). The mixed solutions were stirred for 5 min and left into Teflon-lined stainless steel autoclave treatment at 200°C for 3 and 5 h. The yellow final solution was filtered and dried at 100°C for 24 h. All BiVO4 nanoparticle samples were characterized by X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectrometer (EDXS) and Fourier transform infrared spectrometer (FTIR).

Microwave-assisted Synthesis Bismuth Vanadate (BiVO4) Powder

Bismuth vanadate (BiVO4) powder was synthesized by the microwave method. Bismuth nitrate pentahydrate (Bi(NO3)3.5H2O) and ammonium vanadate (NH4VO3) were used as the starting precursors with the mole ratio of 1:1. The mixed solution was stirred and adjusted the pH of solution to 7 with ammonium hydroxide (NH4OH). The yellow final solution was treated in the microwave with an irradiation power at 600, 700 and 800 Watt for 2, 4 and 6 min, respectively. The phase of BiVO4 powder was identified by X–ray diffraction (XRD). The morphology and chemical composition of BiVO4 powder were investigated by scanning electron microscopy (SEM) and energy dispersive X–ray spectroscopy (EDXS), respectively. The surface area of BiVO4 powder was determined by Brunauer–Emmett–Teller analysis (BET).

The Photocatalytic Degradation of Phenol and Chlorophenol onto Bismuth Vanadate Powder Prepared by the Solvothermal Method

Bismuth vanadate (BiVO4) powder was prepared by the solvothermal method. Bismuth nitrate and ammonium vanadate were used as the starting precursors with mole ratio of 1:1. The mixed solution was heated in the solvothermal vessel at 100°C for 2–6 h. The phase of BiVO4 powder was characterized by X–ray diffractometer (XRD). The morphology and chemical composition of BiVO4 powder were investigated by scanning electron microscope (SEM) and energy dispersive X–ray spectroscope (EDXS). The surface area of BiVO4 powder was determined by Brunauer, Emmett and Teller analyzer (BET). The photocatalytic degradation of phenol and chlorophenol onto BiVO4 powder was studied and determined by gas chromatograph (GC).

Utilization of Expanded Perlite as a Source of Silica for Synthesizing Wollastonite by Solid State Reaction

Naturally occurring volcanic glass in the form of the expanded perlite consist of 72.59wt% silica was used as a starting material together with the calcined eggshell in order to explore the wollastonite formation via solid state reaction. The molar mixing ratios of CaO:SiO2 were carried out from 1:0.8 to 1:1.4, calcined in the range of 600 - 1100°C for 2 - 5 hours. The XRD results confirm the formation of wollastonite (CaSiO3) started at 800°C, and increasing of calcination temperature favoured the formation of gelehnite (Ca2Al2SiO7) associated with wollastonite. The morphology characterized by SEM clearly show tiny needle-like shape of primary wollastonite on the surface of agglomerate particles. The CaO:SiO2 ratio of 1:1.4 which calcined at 1100 °C for 2-5 hours was found to be the most appropriate molar ratio in the case of using the calcined eggshell and expanded perlite as starting materials.

BiVO 4 Powder Synthesized via the Solvothermal Method

Bismuth vanadate (BiVO4) powder was synthesized via the solvothermal method at 100200 °C for 26h by using acetic acid as solvent without calcination steps. The phase transition of BiVO4 powder was studied by Xray diffraction (XRD). The morphology and chemical composition of BiVO4 powder were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The functional groups of BiVO4 powder was identified by Fourier transform infrared spectroscopy (FTIR).

Resonance Raman Enhancement of the ν4 Band in Fe (TMPP)Cl at NIR Laser Excitation Attributed to Supramolecular Interaction

The strong enhancement when applying near-infrared excitation wavelengths, of totally symmetric modes of heme derivatives including β-hematin (malaria pigment), was hypothesized to be due to supramolecular interaction. Specifically, the intensity of the electron density or oxidation state marker band, ν4, is in part strongly affected by CH(((X hydrogen bonding interactions when X is an electron-donating entity. Chlorotetra (p-methoxyphenyl) porphyrinatoiron (III), Fe (TMPP)Cl, is a model compound that supports this hypothesis. The single crystal X-ray structure of Fe (TMPP)Cl, recrystallized by vapor diffusion of diethyl ether into dichloromethane solution, was determined. There are πpor···πpor interactions and numerous additional supramolecular interactions in the form of CH···Cl and CH···O, and CH···π hydrogen bond interactions. The corresponding resonance Raman intensity of Fe (TMPP)Cl exhibited great enhancement of the ν4 band when using 780 and 830 nm laser sources supporting the correlation of the strong CH(((X hydrogen bonding interaction and the strong resonance Raman enhancement of totally symmetric modes, especially ν4, observed in malaria pigment supramolecular arrays when applying near-infrared wavelengths.

Microwave-Assisted Preparation of Sodium Silicate as Biodiesel Catalyst from Rice Husk Ash

In this research, sodium silicate (Na2SiO3) was prepared by rice husk ash reacted with 10 M sodium hydroxide. The mixtures were heated by microwave at 400, 600, and 800 watt for 5 and 10 minutes. The formation of sodium silicate was characterized by Fourier transform infrared spectrophotometer. The vibrations of (Na)O–Si–O(Na) and O–Si–O were observed at 595 and 1023-986 cm-1, respectively, except at 800 watt disappeared those vibrations. The results of flame atomic absorption spectrophotometer provided the mole ratio of sodium and silicon was 2:1 as heating the product at 600 watt for 5 and 10 minutes. The phase of sodium silicate was characterized by X-ray diffraction. Sodium silicate could be used as catalyst as in biodiesel production from palm oil. The percentage of yield was 81 by volume.

The Photocatalytic Degradation of Methomyl over TiO2 Nanopowder Prepared by the Low Temperature Solvothermal Route

Titanium dioxide (TiO2) nanopowder was prepared by the low temperature solvothermal route with starting chemicals containing titanium isopropoxide, ammonium hydroxide, nitric acid and ethanol in a PTFE–lined autoclave. The final pH of the mixed solution was 1 and treated at 100 °C for 2–6 h. The white precipitated was filtered and dried in an oven at 80 °C for 24 h. The phase transition was characterized by X–ray diffractometer (XRD). Single phase anatase structure was obtained without calcination step. The morphology and particle size of TiO2 nanopowder was investigated by scanning electron microscope (SEM). The average of TiO2 nanopowder size was 80–120 nm. The average particle size increased with temperature and time increased. The photocatalytic degradation of methomyl in natural water was studied by high performance liquid chromatograph (HPLC). The percentage of methomyl was decreased in the presence of 34, 23 and 24 over TiO2 nanopowder prepared by the low temperature solvothermal route at 100 °C for 2, 4 and 6 h, respectively.