Anchaleeporn Waritswat Lothongkum

Application of the AERMOD modeling system for environmental impact assessment of NO2 emissions from a cement complex.

We applied the model of American Meteorological Society-Environmental Protection Agency Regulatory Model (AERMOD) as a tool for the analysis of nitrogen dioxide (NO2) emissions from a cement complex as a part of the environmental impact assessment. The dispersion of NO2 from four cement plants within the selected cement complex were investigated both by measurement and AERMOD simulation in dry and wet seasons. Simulated values of NO2 emissions were compared with those obtained during a 7-day continuous measurement campaign at 12 receptors. It was predicted that NO2 concentration peaks were found more within 1 to 5 km, where the measurement and simulation were in good agreement, than at the receptors 5 km further away from the reference point. The Quantile-Quantile plots of NO2 concentrations in dry season were mostly fitted to the middle line compared to those in wet season. This can be attributed to high NO2 wet deposition. The results show that for both the measurement and the simulation using the AERMOD, NO2 concentrations do not exceed the NO2 concentration limit set by the National Ambient Air Quality Standards (NAAQS) of Thailand. This indicates that NO2 emissions from the cement complex have no significant impact on nearby communities. It can be concluded that the AERMOD can provide useful information to identify high pollution impact areas for the EIA guidelines.

A Reaction Flux Model for Extraction of Cu(II) with LIX84I in HFSLM

Hollow fiber supported liquid membrane (HFSLM) is a favorable method to extract both valuable compounds and heavy metal pollutants such as chromium, copper, and nickel at a very low concentration. In this work, the extraction of Cu(II) by LIX84I dissolved in kerosene was theoretically and experimentally investigated. A model to estimate the percentage of extraction of copper ions from synthetic water considering the effect of reaction flux in membrane phase of the HFSLM system was studied. H2SO4 solution was used as the stripping solution. The facilitated transport mechanism of the chemical reaction at the feed-membrane interface was taken into account in the model equations. The percentage of copper ion extraction was plotted against its initial concentration in feed and also feed flow rate. Subsequently, the separation time and separation cycle were determined in accordance with the simulated values of copper ion concentration and the feed flow rate from the model. The modeled results were in good agreement with the experimental data at the average percentage of deviation about 2%.

Arsenic Removal from Natural Gas Condensate using a Pulsed Sieve Plate Column and Mass Transfer Efficiency

This work applied a pulsed sieve plate column in conjunction with liquid-liquid extraction technique to remove arsenic from natural gas condensate. The relevant parameters, that is the type and concentration of the extractant, pulse velocity, volumetric-flow rate ratio of the condensate to the extractant, operating time, and extraction cycle were investigated. Mass transfer efficiency in terms of the overall height of transfer unit (HTU oy , cm) and the interfacial area (m2/m3) were calculated. The highest percentage of arsenic removal in this study was 94% corresponding to the calculated HTU oy of 26 cm and the calculated interfacial area of 118 m2/m3 at the optimum conditions: the mixture of the extractant (1 M hydrochloric acid and 20% (v/v) methanol), pulse velocity of 20 mm/s, and volumetric-flow rate ratio of the condensate to the extractant of 1:4. By using continuous operation in the cycle mode, the percentages of arsenic removal were observed at 94, 85, and 80 from the respective 1st, 2nd, and 3rd cycles. The operation was based on the condition that fresh feed was introduced in each cycle while the extractant was reused.

Modelling and experimental validation of enantioseparation of racemic phenylalanine via a hollow fibre-supported liquid membrane

This paper reports on the enantioseparation of racemic phenylalanine or D-phenylalanine and Lphenylalanine via a hollow fibre-supported liquid membrane (HFSLM) and the results are compared with the mathematical model. The enantioseparation results, of 80 % and 73 %, showed the highest extraction and stripping of l-phenylalanine from the feed phase and the enantiomeric excess (% ee) of 60 % from 6 mmol L−1 of initial rac-phenylalanine in the feed solution. The optimum parameters were feed solution at pH 5, 6 mmol LL−1 of O,O′-dibenzoyl-(2S,3S)-tartaric acid ((+)-DBTA) as the extractant in octanol as the liquid membrane, and deionised water as the stripping solution. Equal flow-rates of feed and stripping solutions of 100 mL minL−1 were adjusted in a batch operation mode for 50 min at ambient temperature. From the calculation, the equilibrium constants of extraction (Kex) and mass transfer coefficients in the feed phase (kf) and in the liquid membrane phase (km) were found to be 1.81 L mmol−2, 3.50 × 10−2 cm s−1, and 1.40 × 10−2 cm s−1, respectively. Finally, the change in concentrations of d,l-phenylalanine over time in the feed and stripping solutions by mathematical model were estimated and compared with the experimental results. The values thus calculated were in agreement with the experimental data with the average deviation of approximately 3 %.

Wear resistance of laser cladded Stellite 31 coating on AISI 316L steel

Abstract Laser cladding of Stellite 31 powder on AISI 316L plate size of 50 × 50 × 25 mm using diode laser powers of 3.5, 4.0, 4.5 and 5.0 kW was produced. The wear tests of clad layers were investigated according to ASTM G99. Equiaxed and elongated grains were found in clad layer using laser powers of 3.5, 4.0 kW and 4.0, 5.0 kW, respectively. Compressive residual stress was detected at the surface of the clad layers. They decreased as laser power increased. After polishing, compressive residual stress and the wear resistance of the clad layers subjected to higher laser power were higher than those subjected to lower laser power. The friction coefficient of the clad layer subjected to higher laser power was lower than that subjected to lower laser power.

Effect of the batch annealing atmosphere on the oxide scale of hot-rolled AISI 430 stainless steel

Abstract The main purpose of this experiment is to study the effect of batch annealing atmospheres on oxide scales by annealing in air, hydrogen and nitrogen at 1123 K for 72, 90 and 108 ks. Grazing incidence x-ray diffraction (GIXRD) and energy dispersive X-ray (EDX) were used to characterize oxide scales after batch annealing process. The morphology and oxide scale of the studied specimens were investigated by scanning electron microscopy (SEM) and optical microscope. Result obtained by GIXRD showed Fe3O4 and spinel FeCr2O4 oxide scales on the as-received hot-rolled specimens. After batch annealing in air, Fe2O3 and (Fe,Cr)2O3 oxide scales were found. Whereas after batch annealing in hydrogen, Fe3O4 and spinel FeCr2O4 oxide scales were found. In addition, after batch annealing in nitrogen, Fe3O4, (Fe,Cr)2O3 and spinel FeCr2O4 oxide scales were seen. Oxide scales after batch annealing in air are thicker than the scales after batch annealing in hydrogen, however thinner than those scales after batch annealing in nitrogen. The oxide scales thickness after batch annealing in hydrogen is quite equivalent to that found in the as-received hot-rolled oxide scales. Cracks were observed perpendicular to the rolling direction. Weight change after batch annealing in air is higher than that after batch annealing in nitrogen and hydrogen, respectively.

Antibacterial activity and nanocomposite properties of monodispersed silver nanoparticles synthesized by the microwave method

Abstract Monodispersed colloidal silver nanoparticles (Ag-NPs) were synthesized by a simple and rapid microwave method. A precursor, AgNO3, was reduced by ethylene glycol (EG) and N,N-dimethylformamide (DMF) in the presence of polyvinylpyrrolidone (PVP) as a stabilizer or capping agent. It was found that the concentration of AgNO3 significantly affected Ag-NPs particle sizes. The particle sizes decreased when the concentration decreased from 0.1 to 0.05 and 0.01 M, which corresponded to narrow size distribution of the particle diameters of approximately 60 to 80, 30 to 40 and 10 to 20 nm. The spherical-shaped monodispersed Ag-NPs were obtained by using a volume ratio of EG to DMF of 2.75 : 2.25, microwave power of 400 W and heating time of 2 min. The volume ratio of EG to DMF and the microwave power influenced the uniformity of the Ag-NPs shape and size, while the heating time had no effect. For antibacterial application, 60–80 and 10–20 nm Ag-NPs showed good disinfection ability against Escherichia coli (ATCC 25922) at the minimum inhibitory concentrations (MIC) of 32 and 16 µg × ml−1, respectively. In addition, the electrical resistance of the nanocomposites of DMF-loaded Ag-NPs (20–50 nm) without PVP on single-walled carbon nanotubes and polyethylene terephthalate (PET) was measured. As a result, it is obvious that the Ag-NPs help to increase the electrical conductivity of the nanocomposites as the electrical resistance of the Ag-NPs nanocomposites was 4.68 kΩ × cm−2 compared to that of the nanocomposites without Ag-NPs of 8.76 kΩ × cm−2.