Chemical Stabilization of Coal Fly Ash for Simultaneous Suppressing of As, B, and Se Leaching

The discard of coal fly ash produced from the combustion of pulverized coal in a coal-fired boiler of thermal power plants has led to environmental concerns. Due to the interaction of fly ash particles with weathering and hydrological processes, the rainfall leaches out toxic elements in coal fly ash from the ash heaps. This situation has been pointed out as a potential contamination of soil, surface, and groundwater. In this chapter, the available fly ash treatment techniques to minimize future release of toxic trace elements (arsenic, boron, and selenium) have been documented, and the recent investigations dealing with leaching suppression effect of arsenic, boron, and selenium from coal fly ash have been reviewed. The leaching characteristics of arsenic, boron, and selenium are discussed, and a simple and low-cost leaching control method is presented in the context of treating the fly ash through chemical stabilization technique using additives containing high levels of calcium. Experimental results described in this chapter show the chemical stabilization technique utilizing Ca-containing additives is an effective technique for simultaneous suppressing of As, B, and Se leaching from coal fly ash

Preliminary Study on Additives for Controlling As, Se, B, and F Leaching from Coal Fly Ash

The application of paper sludge ash as an additive in controlling the leaching of trace elements has been satisfactorily effective to date. Previous studies have found that paper sludge ash has a promising effect in controlling the leaching of arsenic, selenium and boron. The content of calcium oxide in paper sludge ash is believed to be one of the important factors in decreasing the concentration of trace elements in leachate. Therefore, this study aimed to verify the effect of paper sludge ash in the leaching process and to propose an effective and applicable suppressing material that can control the leaching of As, Se, B and F simultaneously. In light of this aim, Ca(OH)2, PS ash 8 and blast furnace cement (BF cement) were tested as single and mixed additives in two different coal fly ashes (FA C and FA H). The results indicate that the application of a mixture of additives is necessary to control the leaching of trace elements. A mixture of PS ash 8, Ca(OH)2 and blast furnace cement (BF cement) was proposed to be an applicable and suitable additive that could suppress arsenic, selenium, boron, and fluorine leaching simultaneously. Keywords: additives; calcium; paper sludge ash; coal fly as

The Role of Calcium Compound on Fluorine Leaching Concentration

The performance of calcium compound in leaching mechanisms has been known through the addition of high calcium compound material. The addition of those materials was proven that the additives could simultaneously inhibit the leaching of several trace elements such as arsenic, selenium, boron and fluorine. This study will be focused on the role of calcium compound onto fluorine leaching concentration. Fluorine is one of trace elements consisting in most of coals that has effect in environmental pollution. The application of mixture additives in leaching process was given a promising effect in inhibit the leaching of fluorine until less the environmental limit (0.8 mg/L). This researched will present the information about calcium compound related with fluorine leaching mechanism after the addition of mixture additives (Ca(OH)2, PS ash 8, and BF cement) into 14 different coal fly ashes (FA A, B, C, B, E, F, G, H, I, J, K, L, M, and N). This information will be important in the coal fly ash utilization to minimize the effect of fluorine leaching concentration into the environment

Antitumor studies. Part 1: Design, synthesis, antitumor activity, and AutoDock study of 2-deoxo-2-phenyl-5-deazaflavins and 2-deoxo-2-phenylflavin-5-oxides as a new class of antitumor agents

Novel 2-deoxo-2-phenyl-5-deazaflavins and 2-deoxo-2-phenylflavin-5-oxides were prepared as a new class of antitumor agents and showed significant antitumor activities against NCI-H 460, HCT 116, A 431, CCRF-HSB-2, and KB cell lines. In vivo investigation, 2-deoxo-10-methyl-2-phenyl-5-deazaflavin exhibited the effective antitumor activity against A 431 human adenocarcinoma cells transplanted subcutaneously into nude mouse. Furthermore, AutoDock study has been done by binding of the flavin analogs into PTK pp60(c-src), where a good correlation between their IC50 and AutoDock binding free energy was exhibited. In particular, 2-deoxo-2-phenylflavin-5-oxides exhibited the highest potential binding affinity within the binding pocket of PTK

Effect of dietary fatty acid composition on Th1/Th2 polarization in lymphocytes.

BACKGROUND: It has become increasingly clear that polyunsaturated fatty acids (PUFAs) have immunomodulatory effects. However, the intake of these fatty acids used in animal studies often greatly exceeds dietary human intake. Whether differences in the composition of fatty acids that are consumed in amounts consistent with normal dietary intake can influence immune function remains uncertain. METHODS: We manufactured 3 types of liquid diet, related to modified fatty acid composition (omega-6/omega-3 = 0.25, 2.27 and 42.9), but excluding eicosapentaenoic acid and docosahexaenoic acid, based upon a liquid diet used clinically in humans. We assessed CD3-stimulated cytokine production of splenocytes in female BALB/c mice (n = 4 per group) fed 1 of 3 liquid diets for 4 weeks. We also measured the cytokine production of peripheral blood mononuclear cells stimulated with phorbol myristate acetate and ionomycin in humans at the end of a 4-week period of consumption of 2 different liquid diets (omega-6/omega-3 = 3 and 44). RESULTS: We found that the ratio of interfero omega-gamma (IFN-gamma) / interleukin-4 (IL-4) was significantly higher in mice fed the omega-3 rich diet than in others. In humans, IFN-gamma / IL-4 was significantly higher after the omega-3 versus the omega-6 enhanced diet. CONCLUSIONS: Differences in the composition of omega-3 and omega-6 PUFAs induces a shift in the Th1/Th2 balance in both mouse and human lymphocytes, even when ingested in normal dietary amounts. An omega-3 rich diet containing alpha-linolenic acid modulates immune function

Hydrogen Production from Ammonia Using Plasma Membrane Reactor

In this study, an efficient method for using pulsed plasma to produce hydrogen from ammonia was developed. An original pulsed plasma reactor with a hydrogen separation membrane was developed for efficient hydrogen production, and its hydrogen production performance was investigated. Hydrogen production in the plasma was affected by the applied voltage and flow rate of ammonia gas. The maximum hydrogen production flow rate of a typical plasma reactor was 8.7 L/h, whereas that of the plasma membrane reactor was 21.0 L/h. We found that ammonia recombination reactions in the plasma controlled hydrogen production in the plasma reactor. In the plasma membrane reactor, a significant increase in hydrogen production was obtained because ammonia recombination reactions were inhibited by the permeation of hydrogen radicals generated in the plasma through a palladium alloy membrane. The energy efficiency was 4.42 mol-H2/kWh depending on the discharge power

Hydrogen Production and Heat Transfer Distributions of Ammonia Decomposition in an Atmospheric Pressure Plasma Plate Reactor

This study extensively investigated the hydrogen production and heat transfer distribution in atmospheric pressure dielectric barrier discharge plasma reactor. Ammonia gas was fed into a plasma plate reactor at flow rates of 0.1-1 L/min with different electrode gap distances of 1 mm and 4.5 mm. The heat transfer distribution was determined for the metallic and dielectric electrodes. The maximum conversion rates of the reactor with electrode gap distances of 4.5 mm, 1 mm were 83% and 19.2%, respectively. At a reactor electrode gap distance of 4.5 mm, the maximum energy efficiencies were 0.193%, 0.178%, and 0.105% at ammonia input flow rates of 1, 0.5, and 0.1 L/min, respectively. The results at an electrode gap distance of 1 mm were 0.042%, 0.038%, and 0.022% at ammonia input flow rates of 1, 0.5 and 0.1 L/min, respectively

Study of the reactor temperature effect on H2 production from steam decomposition using DBD plasma

Heat transfer data for the effect of the reactor and surrounding temperature on the hydrogen production from water vapour decomposition using Dielectric-Barrier Discharge (DBD) plasma are reported. The water vapour was injected into the plate micro channel reactor (PMCR) where the PMCR and its surrounding temperatures were raised using an insulated constant temperature heater type in a range of 20-130°C. This experiment was run at the following steam inlet conditions: pressure 100 kPa, temperature 300°C and flow rates of 100-200 ml/h, while the plasma applied voltage was in a range of 14-18 kV. In particular, the concentrations of hydrogen and oxygen species were analysed using gas phase chromatography (GC). It was observed that the hydrogen concentration percent increased with the reactor and surrounding temperature increased at all tested steam flow rates. Also, it was seen that the maximum obtained H2 concentrations were at high reactor temperature 130°C and plasma applied voltage of 18 kV. The effect of reactor temperature on the total heat transfer resistances at different steam flow rates was investigated. The trend behaviour of these resistances reveals interesting information about how these resistances interact and distribute according to the reactor heating temperature. Also, it was found that the total heat transfer rate decreased with the reactor temperature increased while the overall heat transfer rate increased with plasma voltage and reactor heating temperature. It can be concluded that the DBD plasma effect improved by decreasing the temperature difference between input steam and the PMCR temperatures. Further, it was clear that the steam dissociation processes not mainly depending on the plasma applied voltage but also the reactor heating temperature

Exposure Assessment of Mercury and Its Compounds by Dispersion Modeling: A Case Study in the Sea of Japan Coastal Area

In Japan, mercury and its compounds were categorized as hazardous air pollutants in 1996 and are on the list of “Substances Requiring Priority Action” published by the Central Environmental Council of Japan. The Air Quality Management Division of the Environmental Bureau, Ministry of the Environment, Japan, selected the current annual mean environmental air quality standard for mercury and its compounds of 0.04 μg/m 3 . Long-term exposure to mercury and its compounds can have a carcinogenic effect, inducing eg, Minamata disease. This study evaluates the impact of mercury emissions on air quality in the coastal area of the Sea of Japan. Average yearly emission of mercury from an elevated point source in this area with background concentration and one-year meteorological data were used to predict the ground level concentration of mercury. The annual mean concentration distribution of mercury and its compounds were calculated for the middle part of Honshu Island, which served as a background level of mercury concentration for the coastal are of the Sea of Japan. To estimate the concentration of mercury and its compounds in air of the local area, two different simulation models have been used. The first is the National Institute of Advanced Science and Technology Atmospheric Dispersion Model for Exposure and Risk Assessment (AIST-ADMER) that estimates regional atmospheric concentration and distribution. The second is the Ministry of Economy, Trade and Industry Low Rise Industrial Source Dispersion Model (METI-LIS) that estimates the atmospheric concentration distribution in the vicinity of facilities

Effect of Additives on Arsenic, Boron and Selenium Leaching from Coal Fly Ash

The establishment of an inexpensive leaching control method to prevent the leaching of trace elements from fly ash is required for the utilization of large-scale fly ash as an embankment material. This study examined the effects of the additives on suppressing As, B, and Se leaching from coal fly ash using Ca(OH)2, paper sludge ashes (PS Ash 3, PS Ash 4 and PS Ash 5), and filter cake (FC). PS Ash and FC are waste generated in the papermaking and lime industry processes and contain high levels of calcium. The treated fly ash H (FAH) and the resulting mixtures were subjected to a leaching test as per the Environmental Agency of Japan Notifications No. 13. The results indicate that the leaching concentrations of As, B, and Se could be greatly reduced in FAH with the highest effect given by Ca(OH)2, followed by PS Ash 3 and PS Ash 5. Ca(OH)2 greatly reduced both the leaching concentrations of As, B, and Se by about 91–100%, while PS Ash 3 reduced the As and B leaching concentrations by approximately 89–96% and 83–92%, respectively; and PS Ash 5 reduced the Se leaching concentration by about 87–96%. FC did not have any impact on As and B leaching, but reduced Se leaching by about 58–78%. A reason for the decrease in leaching concentrations of As, B, and Se may be the precipitation with calcium or the formation of ettringite. The presence of leached Ca and Na ions are key factors affecting the decrease of As, B, and Se leaching concentrations from fly ash. The utilization of PS Ash 3 and PS Ash 5 as inexpensive additives is a promising method to control the leaching of As, B, and Se into the environment