Comparative Study between ADMS and CFD in Modeling Dust Dispersion from a Blasting Events in Quarry

Two frequently used methods in atmospheric dispersion modeling (ADMS and CFD) were compared in this study to predict pit retention within an open quarry. Conventional Gaussian plume models developed by CERC, ADMS 3 and ADMS 4, were used to predict the pit retention. This study mimicked Fluent CFD modeling of dust dispersion of a blasting event in Old Moor Quarry.  A single blast event that liberated a typical 25,000 tons of rock released 1,900 kg of Total Suspended Particle (TSP). The emission source geometry was defined as a three dimensional block volume source of 70 m normal to the face, 80 m in width and 20 m in height. It was also assumed the TSP liberated over one hour had an emission rate of 4.71x10-3 g/m3/s. The four particle sizes were defined as 2.5, 10, 30 and 75 m at mass fractions of 0.05, 0.45, 0.3 and 0.2 respectively and the particles were assumed have uniform limestone density of 2600 kg/m3. The results indicated that ADMS and model based on CFD indicates similar trend, that is, pit retention is proportional to distance from source to pit edge along wind direction and proportional to inverse quarry gradient.Keywords: dust dispersion, blasting, ADMS, CFD, pit retentio

Microwave Assisted Co/SiO2 preparation for Fischer-Tropsch synthesis

Cobalt catalyst has been widely used for Fischer-Tropsch (FT) Synthesis in Industry. The most common method to prepare cobalt catalyst is impregnations. Metal is deposited on porous support by contacting dry support with solution containing dissolved cobalt precursor. This step will follow by drying, calcination and reduction. The heating step used in this conventional method, however, may lead to the formation of metal silicate which is inactive site for catalysis.  In this study, author explore the use of microwave to prepare catalyst compared to conventional drying method. Cobalt catalyst with SiO2 support was prepared and characterized. Particle size, surface area, and cobalt content were investigated. Crystallite size of 3-8 nm was formed which was reported to be the optimum size for cobalt catalyst in FT Synthesis. Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM) image revealed that microwave catalyst showed better uniformity and cobalt dispersion on silica support. Thermo-Gravimetric Analysis (TGA) study also indicated that this catalyst has good stability at Low Temperature Fischer-Tropsch Synthesis. The catalysts were then applied plasma assisted FT process over a range of power plasma (20-60W) to investigate the effect on the conversion and selectivity. The results showed that microwave catalyst exhibit lower CO conversion at 42.06% compared to conventional method at 68.32%. However, microwave catalyst is more favourable for long chain hydrocarbon selectivity

Differential tolerance of Trichoderma harzianum and Rhizoctonia solani towards silver nanoparticles: potential for agricultural applications?

In the previous study, we examined the effect of silver nanoparticles (AgNPs) on beneficial soil fungus including Trichoderma harzianum (T22), and pathogenic soil-borne fungus, Rhizoctonia solani (AG3-PT). The result exhibited that T. harzianum (T22) is tolerance towards AgNPs. On the other hand, the pathogenic fungi, R.solani (AG3-PT), is more sensitive to AgNPs. T. harzianum is well known as biocontrol agent to suppress R. solani. Therefore, in this study we investigated the combination of T. harzianum (T22) and AgNPs at low concentration to control two strains of R. solani (AG3-PT and AG2-1). The effect of AgNPs at two different levels (20 mg L-1 and 50 mg L-1) was examined over the growth of the two strains of R. solani and T. harzianum (T22) using dual culture technique. The results shows that this combination have a potential to reduce colony growth of R. solani (AG2-1) at higher AgNPs concentration. However, it was not the case for R. solani (AG3-PT). It can be concluded that AgNPs toxicity depend on several factors including species strain and the size of AgNPs particle

Intensification of Synthesis of Fatty Acid Isopropyl Ester using Microwave

Fatty acid isopropyl ester is one of the derivative products from vegetable oils such as crude palm oil (CPO). Chemically, fatty acid isopropyl esters can be synthesized from oils or vegetable fats with isopropanol using inorganic catalysts. The purpose of this research was to intensify the process of synthesis of fatty acid isopropyl esters from CPO using microwaves. Research variables used were CPO to isopropanol molar ratios of 1:3, 1:5, 1:7, 1:9, 1:11, and 1:13; reaction times of 1, 3, and 5 minutes; and KOH catalyst concentrations of 0.10, 0.15, 0.20, and 0.30 (%-w of CPO). The experimental result showed that the process variables affected the yield of fatty acid isopropyl esters. The highest yield obtained (80.5%) was found at molar ratio of CPO to isopropanol of 1:11, catalyst concentration of 0.2% (%-w of CPO), and reaction time of 5 minutes. With the same conditions, a 72.2% yield was obtained in 150 minutes using conventional transesterification. Fourier transform infrared analysis showed some specific functional groups in fatty acid isopropyl esters. In addition, viscosity, density, and acid number of fatty acid isopropyl esters produced conformed to the Indonesian National Standard (SNI) No. 7182-2015

Comparative Study between ADMS and CFD in Modeling Dust Dispersion from a Blasting Events in Quarry

Two frequently used methods in atmospheric dispersion modeling (ADMS and CFD) were compared in this study to predict pit retention within an open quarry. Conventional Gaussian plume models developed by CERC, ADMS 3 and ADMS 4, were used to predict the pit retention. This study mimicked Fluent CFD modeling of dust dispersion of a blasting event in Old Moor Quarry.  A single blast event that liberated a typical 25,000 tons of rock released 1,900 kg of Total Suspended Particle (TSP). The emission source geometry was defined as a three dimensional block volume source of 70 m normal to the face, 80 m in width and 20 m in height. It was also assumed the TSP liberated over one hour had an emission rate of 4.71x10-3 g/m3/s. The four particle sizes were defined as 2.5, 10, 30 and 75 m at mass fractions of 0.05, 0.45, 0.3 and 0.2 respectively and the particles were assumed have uniform limestone density of 2600 kg/m3. The results indicated that ADMS and model based on CFD indicates similar trend, that is, pit retention is proportional to distance from source to pit edge along wind direction and proportional to inverse quarry gradient. Keywords: dust dispersion, blasting, ADMS, CFD, pit retentio

A study on CO2 and CH4 conversion to synthesis gas and higher hydrocarbons by the combination of catalysts and dielectric-barrier discharges

The conversion of CH4 and CO2 to synthesis gas (H2 + CO) and higher hydrocarbons was investigated over BaTiO3, glass, Ni/SiO2, NiFe/SiO2, and a mixture of Ni/SiO2 and BaTiO3 in dielectric-barrier discharges (DBDs) at low temperatures and ambient pressure. The fresh and spent Ni/SiO2 catalyst samples were characterized by SEM, XRD, BET and TEM. The variation of the permittivity of packing materials with the same size did not influence the reaction significantly. Exposing one metal electrode to plasma could enhance the selectivity to CO in the reaction. The conversion of CO2 and CH4 decreased in the sequence of BaTiO3 > NiFe/SiO2 > Ni/SiO2. A NiFe/SiO2 catalyst increased the selectivity to H2, and both Ni/SiO2 and NiFe/SiO2 catalysts enhanced the selectivity to CO in the reaction. A reaction mechanism of plasma assisted CO2 and CH4 conversion was proposed. Specific input energy (SIE) was an important factor affecting the reaction, and it was possible to alter the product selectivity by optimizing the residence time at a certain SIE over a Ni/SiO2 catalyst