 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Natural Radionuclide Contents in Ceramic Clays in Southern Thailand and their Radiation Hazard Indices) ผู้เขียน: Sunaree Bordeepong, Darunee Bhongsuwan, Thongchai Pungrassami, Tripob Bhongsuwan สื่อสิ่งพิมพ์:pdf AbstractThe present study aimed to: 1) measure the natural radioactivity due to the presence of radionuclides in natural clay, used widely as raw material in the ceramics industry; and 2) assess the possible radiological hazard associated with the ceramic products made with them. Natural clays from 17 localities in southern Thailand and commercial clay used in ceramics and pottery factories were studied. The activity concentrations of natural radionuclides, Th-232, Ra-226 and K-40, were measured by means of low background gamma-ray spectroscopy with a high purity germanium detector. The measured activity concentrations of Th-232, Ra-226 and K-40 of all clay samples ranged from 83 to 476, 67 to 576 and 161 to 1200 Bq/kg, respectively. These levels were comparable to those of other clays globally. The calculated radium equivalents varied from 327 to 1226 Bq/kg, with the average value (662 Bq/kg) being significantly higher than the standard criterion of 370 Bq/kg. The external hazard indices varied from 0.88 to 3.31, with an average of 1.79, which was higher than the standard criterion (1). The gamma radiation hazard indices of all samples studied ranged from 1.14 to 4.22, which were below the criterion limit (< 6) corresponding to a dose rate <1 mSv/y for superficial use and use with other materials with restricted use, but were higher than the criterion limit (1) when used in bulk amounts. Therefore, the hazard indices should be reduced by choosing carefully among the clays studied and other mixing ingredients. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Preparation of Cellulose Acetate Membranes for Ultra- Nano- Filtrations) ผู้เขียน:Darunee Bhongsuwan, Tripob Bhongsuwan สื่อสิ่งพิมพ์:pdf AbstractCellulose acetate (CA) membranes were prepared from CA powder, formamide and acetone by phase inversion. Production conditions used included evaporation times of 20, 30 and 60 seconds, gelation temperature of 1 – 2 ?C and annealing temperature of 70 and 75?C. The product membranes were coded CA620-70, CA630-70 CA660-70, CA620-75, CA630-75 and CA660-75 and were tested to have Molecular weight cutoff (MWCO) between 1500 and 10000 Da. The pure water flux tests classified the membranes CA620-70, CA630-70 CA660-70, CA620-75 as ultra-filtration type and CA630-75 and CA660-75 as nano-filtration membranes. Tannin was easily filtered with the rejection of 78 - 100 % for different membrane types and pressures. Rejection of protein BSA was successful at nearly 100 % rejection for all the product membranes. SEM micrographs showed an average pore longest axis of 0.066 ? 0.029 micron and pore densities of 1.95 – 3.02 pores/micron2. The membrane strength was tested to have the ultimate tensile strength of 1.64 – 2.82 N, Young’s modulus of 54.74 – 175.36 MPa and the percent elongation at failure of 15.57 – 23.00 |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Mineralogy, Chemical Composition and Ceramic Properties of Clay Deposits in Southern Thailand) ผู้เขียน:Sunaree Bordeepong, Darunee Bhongsuwan, Thongchai Pungrassami, Tripob Bhongsuwan สื่อสิ่งพิมพ์:pdf AbstractThe mineralogical, chemical composition and ceramic properties of clay deposits from southern Thailand were studied to assess their potential for use in the ceramics industry. Samples were collected from 11 localities where clay mining and processing plants are active in southern Thailand. X-ray powder diffraction patterns with sample treatments by glycolation and heat treatment were used to analyze the clay and non-clay minerals and the X-ray fluorescence method was used for elemental analysis. The data collected from these techniques showed that the clay minerals were kaolinite, halloysite and illite and the non-clay minerals consisted of quartz, microcline, gibbsite and anatase. The results from the chemical analysis of the clay samples showed that the most important components were SiO2 (46.75–63.17%) and Al2O3 (20.01–37.03%), since they have a conclusive influence on the refractoriness and strength of the final product. Firing characteristics from 800 to 1,300 ?C were used to determine firing shrinkage, color, bulk density, modulus of rupture, water absorption and phase transformation. Ranong clays had the necessary properties for the manufacturing of ceramic products. However, for clays from Nakhon Si Thammarat, Surat Thani and Songkhla, it will be necessary to add other components to enhance their workability. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Magnetic Properties of Magnetite Nanoparticles Synthesized by Oxidative Alkaline Hydrolysis of Iron Powder) ผู้เขียน:Nucharee Chomchoey, Darunee Bhongsuwan, Tripob Bhongsuwan สื่อสิ่งพิมพ์:pdf AbstractThe black magnetic nanoparticles (MNPs) of magnetite (Fe3O4) were synthesized by oxidative alkaline hydrolysis of the atomized iron powder precursor. The synthesized particles prepared at different precipitation temperatures were characterized using X-ray powder diffraction (XRD), the Brunauer– Emmett–Teller (BET) method and transmission electron microscopy (TEM). Their magnetic properties were examined using a vibrating sample magnetometer (VSM), measurement of the initial magnetic susceptibility, acquisition of the isothermal remanent magnetization (IRM) and alternating field (AF) demagnetization of the acquired IRM. The results showed that the sizes of MNPs depended upon the precipitation temperature, which affected the magnetic susceptibility, magnetic hysteresis properties and remanent properties of the synthesized MNPs. The maximum grain size, magnetic susceptibility and magnetic hysteresis properties were obtained from the MNPs synthesized at a precipitation temperature of 70?C. The MNPs prepared by this method exhibited a cubo-octahedral structure with average particle sizes of 25-70 nm. Room temperature magnetic hysteresis properties confirmed the ferromagnetic behavior of stable single domain particles with saturation magnetization of 11.64-77.45 emu/g, remanent magnetization of 1.28-15.769 emu/g, and coercivity of 112.42-158.03 G. |