Displaying publications 1 - 20 of 129 in total

Abstract:
Sort:
  1. Lee KT, Bhatia S, Mohamed AR, Chu KH
    Chemosphere, 2006 Jan;62(1):89-96.
    PMID: 15996711
    High performance sorbents for flue gas desulfurization can be synthesized by hydration of coal fly ash, calcium sulfate, and calcium oxide. In general, higher desulfurization activity correlates with higher sorbent surface area. Consequently, a major aim in sorbent synthesis is to maximize the sorbent surface area by optimizing the hydration conditions. This work presents an integrated modeling and optimization approach to sorbent synthesis based on statistical experimental design and two artificial intelligence techniques: neural network and genetic algorithm. In the first step of the approach, the main and interactive effects of three hydration variables on sorbent surface area were evaluated using a full factorial design. The hydration variables of interest to this study were hydration time, amount of coal fly ash, and amount of calcium sulfate and the levels investigated were 4-32 h, 5-15 g, and 0-12 g, respectively. In the second step, a neural network was used to model the relationship between the three hydration variables and the sorbent surface area. A genetic algorithm was used in the last step to optimize the input space of the resulting neural network model. According to this integrated modeling and optimization approach, an optimum sorbent surface area of 62.2m(2)g(-1) could be obtained by mixing 13.1g of coal fly ash and 5.5 g of calcium sulfate in a hydration process containing 100ml of water and 5 g of calcium oxide for a fixed hydration time of 10 h.
    Matched MeSH terms: Coal Ash
  2. Pariatamby A, Subramaniam C, Mizutani S, Takatsuki H
    Environ Sci, 2006;13(5):289-96.
    PMID: 17096003
    Fly ash samples from a mixed hazardous waste (MHW) incinerator were subjected to solidification and stabilization (S/S) studies using ordinary Portland cement (OPC) as the binder. Additives (i.e., activated carbon and rice husk) were also homogenized with the binder and waste to determine the effectiveness of the immobilization of heavy metals. The toxicity characteristics leaching procedure (TCLP), Japanese Leaching Test (JLT-13) and the American Nuclear Test 16.1 (modified) ANS 16.1 were used to gauge the leaching of heavy metals from the solidified matrixes. Compressibility strength of the solidified matrixes was also tested using the American Standard Testing Material (ASTM) test procedure for the compressive strength of hydraulic cement mortars.
    Matched MeSH terms: Coal Ash
  3. Raymond-Ooi EH, Lee KT, Mohamed AR, Chu KH
    PMID: 16423725
    The mechanistic modeling of the sulfation reaction between fly ash-based sorbent and SO2 is a challenging task due to a variety reasons including the complexity of the reaction itself and the inability to measure some of the key parameters of the reaction. In this work, the possibility of modeling the sulfation reaction kinetics using a purely data-driven neural network was investigated. Experiments on SO2 removal by a sorbent prepared from coal fly ash/CaO/CaSO4 were conducted using a fixed bed reactor to generate a database to train and validate the neural network model. Extensive SO2 removal data points were obtained by varying three process variables, namely, SO2 inlet concentration (500-2000 mg/L), reaction temperature (60-80 degreesC), and relative humidity (50-70%), as a function of reaction time (0-60 min). Modeling results show that the neural network can provide excellent fits to the SO2 removal data after considerable training and can be successfully used to predict the extent of SO2 removal as a function of time even when the process variables are outside the training domain. From a modeling standpoint, the suitably trained and validated neural network with excellent interpolation and extrapolation properties could have immediate practical benefits in the absence of a theoretical model.
    Matched MeSH terms: Coal Ash
  4. Khairul Nizar Ismail, Kamarudin Hussin, Mohd Sobri Idris
    MyJurnal
    Fly ash is the finely divided mineral residue resulting from the combustion of coal in electric generating plants. Fly ash consists of inorganic, incombustible matter present in the coal that has been fused during combustion into a glassy, amorphous structure. Fly ash particles are generally spherical in shape and range in size from 2 μm to 10 μm. They consist mostly of silicon dioxide (SiO2), aluminium oxide (Al2O3) and iron oxide (Fe2O3). Fly ash like soil contains trace concentrations of the following heavy metals: nickel, vanadium, cadmium, barium, chromium, copper, molybdenum, zinc and lead. The chemical compositions of the sample have been examined and the fly ash are of ASTM C618 Class F.
    Matched MeSH terms: Coal; Coal Ash
  5. Faizul Che Pa, Mohd. Zaheruddin Kasmuin, Suhaina Ismail, Norlia Baharun
    MyJurnal
    Fly ash (PFA) is a complex material produced after combustion in coal-fired power plants. About half of this fly ash is disposed as solid wastes. A possible alternative to disposal of the fly ash is the synthesis of zeolite. Zeolite Boggsite (Na37Ca74Al185Si775O192 7H2O) was synthesized from fly ash by hydrothermal treatment with NaOH solutions as identified by x-ray diffraction. The zeolite type and degree of crystallization were found to be dependent on the reaction conditions and mineralogy of the raw material, particularly in terms of the relative concentrations of SiO2 and Al2O3.
    Matched MeSH terms: Coal; Coal Ash
  6. Khoo KS, Lim AL, Sukiman Sarmani
    Sains Malaysiana, 2007;36:45-52.
    Characterisation of the leaching behaviour of coal fly ash from Tenaga Nasional Berhad (TNB) by using tank leaching test method has been reported. The leachability of the constituents such as major elements and toxic metals in the coal fly ash was studied. Eight renewed leachant solutions after 6 hours, 1, 2, 5, 8, 21, 36 and 64 days were investigated after filtration. The parameters namely pH, cumulative release regarding the major elements and toxic metals to duration were presented. The results showed that the pH solutions increased from pH 4 to neutral and remained stable during the test. It might have resulted from the large buffering capacity of the coal fly ashes. Five major elements namely Al, Ca, K, Mg and Na were detected with Ca concentration in the leachant solutions was the highest for all samples. Toxic metals such as As, Ba, Co, Cr, Mn, Ni, Pb, Se and Zn were found and the test showed consistent results on the As, Ba, Mn, Se and Zn in leachant solutions. The findings also showed that some of the toxic metal concentrations namely As, Ba, Cr, Pb and Se exceeded the maximum allowance of the guideline of drinking water quality in Malaysia and WHO. Obviously, proper waste management has to be applied in this scenario.
    Matched MeSH terms: Coal; Coal Ash
  7. Yin CY, Wan Ali WS, Lim YP
    J Hazard Mater, 2008 Jan 31;150(2):413-8.
    PMID: 17543446
    In this study, solidification/stabilization (S/S) of nickel hydroxide sludge using ordinary Portland cement (OPC) and oil palm ash (OPA) was carried out. The effects of increased substitution of OPA wt% in the S/S mix designs on the treated samples' physical and chemical characteristics were investigated. The physical characteristics studied were unconfined compressive strength (UCS) and changes in crystalline phases while chemical characteristics studied were leachability of nickel and leachate pH. Results indicated the optimum mix design for S/S of nickel hydroxide sludge using both OPC and OPA at B/S(d)=1 in terms of cost-effectiveness and treatment efficiency was 15 wt% OPA, 35 wt% OPC and 50 wt% sludge. The sufficient UCS and low leached nickel concentrations shown for this mix design indicate the viability of using OPA as substitute of OPC as it can significantly reduce cost normally incurred by usage of high amounts of OPC.
    Matched MeSH terms: Coal Ash
  8. Muneer Saleh, Ahmad Suhaimi
    MyJurnal
    An instrumental neutron activation analytical (INAA) technique is used for the determination of thirty elements in five coal samples collected from Kapar power station, imported from Indonesia and Australia. Analyses of the samples are being associated with standards. All irradiations were performed in the nuclear reactor of Malaysia Nuclear Agency (MNA). Samples were counted by Hyper Pure Germanium (HPGe) detector for short period irradiations at MNA, while for the long period irradiations the samples were counted at Universiti Kebangsaan Malaysia (UKM). The concentrations of thirty elements have been determined: The major components are Cl, Ca, Mg, K, Fe, Ti and Na with the mean concentrations in the range between 70±69 ppm- 6100±1639 ppm; and the trace elements are Zr, V, Mn , Sc, Cr, Co, As ,Br ,Rb ,Sb ,Ba , La, Ce, Nd, Sm, Eu, Tb, Yb, Lu, Hf, Th, U and Ta with the mean concentrations in the range between 0.1381±0.0202 - 69.0±2.8 ppm. The results have been compared to the reported data of eight coal samples from the United States and the reported data of Australian bituminous coal.
    Matched MeSH terms: Coal
  9. Ghani WA, Alias AB, Savory RM, Cliffe KR
    Waste Manag, 2009 Feb;29(2):767-73.
    PMID: 18614348 DOI: 10.1016/j.wasman.2008.03.025
    Power generation from biomass is an attractive technology that utilizes agricultural residual waste. In order to explain the behavior of biomass-fired fluidized bed incinerator, biomass sources from agricultural residues (rice husk and palm kernel) were co-fired with coal in a 0.15m diameter and 2.3m high fluidized bed combustor. The combustion efficiency and carbon monoxide emissions were studied and compared with those for pure coal combustion. Co-combustion of a mixture of biomass with coal in a fluidized bed combustor designed for coal combustion increased combustion efficiency up to 20% depending upon excess air levels. Observed carbon monoxide levels fluctuated between 200 and 900 ppm with the addition of coal. It is evident from this research that efficient co-firing of biomass with coal can be achieved with minimal modifications to existing coal-fired boilers.
    Matched MeSH terms: Coal*
  10. Hashim R, Jackson DC
    Trop Life Sci Res, 2009 Dec;20(2):29-47.
    PMID: 24575177 MyJurnal
    A three-year study (July 2000 - June 2003) of fish assemblages was conducted in four tributaries of the Big Black River: Big Bywy, Little Bywy, Middle Bywy and McCurtain creeks that cross the Natchez Trace Parkway, Choctaw County, Mississippi, USA. Little Bywy and Middle Bywy creeks were within watersheds influenced by the lignite mining. Big Bywy and Middle Bywy creeks were historically impacted by channelisation. McCurtain Creek was chosen as a reference (control) stream. Fish were collected using a portable backpack electrofishing unit (Smith-Root Inc., Washington, USA). Insectivorous fish dominated all of the streams. There were no pronounced differences in relative abundances of fishes among the streams (P > 0.05) but fish assemblages fluctuated seasonally. Although there were some differences among streams with regard to individual species, channelisation and lignite mining had no discernable adverse effects on functional components of fish assemblages suggesting that fishes in these systems are euryceous fluvial generalist species adapted to the variable environments of small stream ecosystems.
    Matched MeSH terms: Coal
  11. Razak HA, Naganathan S, Hamid SN
    J Hazard Mater, 2009 Dec 30;172(2-3):862-7.
    PMID: 19665294 DOI: 10.1016/j.jhazmat.2009.07.070
    Controlled low-strength material (CLSM) is slurry made by mixing sand, cement, ash, and water. It is primarily used as a replacement for soil and structural fillings. This paper presents the findings of a preliminary investigation carried out on the performance of industrial waste incineration bottom ash as CLSM. CLSM mixes were designed using industrial waste incineration bottom ash, and cement. Tests for density, setting time, bleed, and compressive strength on cubes under various curing conditions, corrosivity, and leaching of heavy metals and salts were carried out on the CLSM mixtures, and the results discussed. Compressive strength for the designed CLSM mixtures ranged from 0.1 to 1.7 MPa. It is shown that the variations in curing conditions have less influence on the compressive strength of CLSM at high values of water to cement ratio (w/c), but low values of w/c influences the strength of CLSM. The CLSM produced does not exhibit corrosive characters as evidenced by pH. Leaching of heavy metals and salts is higher in bleed than in leachate collected from hardened CLSM. Cement reduces the leaching of Boron in bleed. It is concluded that there is good potential for the use of industrial waste incineration bottom ash in CLSM.
    Matched MeSH terms: Coal Ash
  12. Idris SS, Abd Rahman N, Ismail K, Alias AB, Abd Rashid Z, Aris MJ
    Bioresour Technol, 2010 Jun;101(12):4584-92.
    PMID: 20153633 DOI: 10.1016/j.biortech.2010.01.059
    This study aims to investigate the behaviour of Malaysian sub-bituminous coal (Mukah Balingian), oil palm biomass (empty fruit bunches (EFB), kernel shell (PKS) and mesocarp fibre (PMF)) and their respective blends during pyrolysis using thermogravimetric analysis (TGA). The coal/palm biomass blends were prepared at six different weight ratios and experiments were carried out under dynamic conditions using nitrogen as inert gas at various heating rates to ramp the temperature from 25 degrees C to 900 degrees C. The derivative thermogravimetric (DTG) results show that thermal decomposition of EFB, PMF and PKS exhibit one, two and three distinct evolution profiles, respectively. Apparently, the thermal profiles of the coal/oil palm biomass blends appear to correlate with the percentage of biomass added in the blends, thus, suggesting lack of interaction between the coal and palm biomass. First-order reaction model were used to determine the kinetics parameters for the pyrolysis of coal, palm biomass and their respective blends.
    Matched MeSH terms: Coal/analysis*
  13. Lau LC, Lee KT, Mohamed AR
    J Hazard Mater, 2010 Nov 15;183(1-3):738-45.
    PMID: 20724075 DOI: 10.1016/j.jhazmat.2010.07.088
    In order to reduce the negative impact of coal utilization for energy generation, the pollutants present in the flue gas of coal combustion such as sulfur dioxide (SO(2)) and nitrogen oxide (NO) must be effectively removed before releasing to the atmosphere. Thus in this study, sorbent prepared from rice husk ash that is impregnated with copper is tested for simultaneous removal of SO(2) and NO from simulated flue gas. The effect of various sorbent preparation parameters; copper loading, RHA/CaO ratio, hydration period and NaOH concentration on the sorbent desulfurization/denitrification capacity was studied using Design-Expert Version 6.0.6 software. Specifically, Central Composite Design (CCD) coupled with Response Surface Method (RSM) was used. Significant individual parameters that affect the sorbent capacity are copper loading and NaOH concentration. Apart from that, interaction between the following parameters was also found to have significant effect; copper loading, RHA/CaO ratio and NaOH concentration. The optimum sorbent preparation condition for this study was found to be 3.06% CuO loading, RHA/CaO ratio of 1.41, 8.05 h of hydration period and NaOH concentration of 0.80 M. Sorbent characterization using SEM, XRD and surface area analysis were used to describe the effect of sorbent preparation parameters on the desulfurization/denitrification activity.
    Matched MeSH terms: Coal/adverse effects
  14. Asnor Azrin Sabuti, Che Abd Rahim Mohamed, Zaharudin Ahmad
    MyJurnal
    Various environmental samples (seawater, TSS, sediment, rainwater and fly ash) from eight different stations near Kapar coastal area were analyzed. The 210 Po activity concentrations in liquid samples (seawater and rainwater) varied between 0.34 ± 0.03 mBq L-1 to 22.44 ± 0.53 mBq L-1 . Whereas the concentrations in particulate samples (TSS, sediment and fly ash) varied between 43.79 ± 2.31 Bqkg-1 to 364.48 ± 5.43 Bqkg-1 . Results also showed the radioactivity in Kapar coastal is higher than most of Malaysian coast, reaching a factor of seven. This condition is mainly due to the operation of a coal-fired power plant nearby. This study also clarify the variability of 210 Po in environment was strongly influenced from rainfall events especially during wet seasons.
    Matched MeSH terms: Coal; Coal Ash
  15. Alam L, Mohamed CA
    Environ Health, 2011 May 20;10:43.
    PMID: 21595985 DOI: 10.1186/1476-069X-10-43
    BACKGROUND: Po²¹⁰ can be accumulated in various environmental materials, including marine organisms, and contributes to the dose of natural radiation in seafood. The concentration of this radionuclide in the marine environment can be influenced by the operation of a coal burning power plant but existing studies regarding this issue are not well documented. Therefore, the aim of this study was to estimate the Po²¹⁰ concentration level in marine organisms from the coastal area of Kapar, Malaysia which is very near to a coal burning power plant station and to assess its impact on seafood consumers.

    METHODS: Concentration of Po²¹⁰ was determined in the edible muscle of seafood and water from the coastal area of Kapar, Malaysia using radiochemical separation and the Alpha Spectrometry technique.

    RESULTS: The activities of Po²¹⁰ in the dissolved phase of water samples ranged between 0.51 ± 0.21 and 0.71 ± 0.24 mBql⁻¹ whereas the particulate phase registered a range of 50.34 ± 11.40 to 72.07 ± 21.20 Bqkg⁻¹. The ranges of Po²¹⁰ activities in the organism samples were 4.4 ± 0.12 to 6.4 ± 0.95 Bqkg⁻¹ dry wt in fish (Arius maculatus), 45.7 ± 0.86 to 54.4 ± 1.58 Bqkg⁻¹ dry wt in shrimp (Penaeus merguiensis) and 104.3 ± 3.44 to 293.8 ± 10.04 Bqkg⁻¹ dry wt in cockle (Anadara granosa). The variation of Po²¹⁰ in organisms is dependent on the mode of their life style, ambient water concentration and seasonal changes. The concentration factors calculated for fish and molluscs were higher than the recommended values by the IAEA. An assessment of daily intake and received dose due to the consumption of seafood was also carried out and found to be 2083.85 mBqday⁻¹person⁻¹ and 249.30 μSvyr⁻¹ respectively. These values are comparatively higher than reported values in other countries. Moreover, the transformation of Po²¹⁰ in the human body was calculated and revealed that a considerable amount of Po²¹⁰ can be absorbed in the internal organs. The calculated values of life time mortality and morbidity cancer risks were 24.8 × 10⁻⁴ and 34 × 10⁻⁴ respectively which also exceeded the recommended limits set by the ICRP.

    CONCLUSIONS: The findings of this present study can be used to evaluate the safety dose uptake level of seafood as well as to monitor environmental health. However, as the calculated dose and cancer risks were found to cross the limit of safety, finding a realistic way to moderate the risk is imperative.

    Matched MeSH terms: Coal
  16. Jie Y, Ismail NH, Jie X, Isa ZM
    J Formos Med Assoc, 2011 Sep;110(9):555-63.
    PMID: 21930065 DOI: 10.1016/j.jfma.2011.07.003
    This review summarizes the results of epidemiological studies focusing on the detrimental effects of home environmental factors on asthma morbidity in adults. We reviewed the literature on indoor air quality (IAQ), physical and sociodemographic factors, and asthma morbidity in homes, and identified commonly reported asthma, allergic, and respiratory symptoms involving the home environment. Reported IAQ and asthma morbidity data strongly indicated positive associations between indoor air pollution and adverse health effects in most studies. Indoor factors most consistently associated with asthma and asthma-related symptoms in adults included fuel combustion, mold growth, and environmental tobacco smoke. Environmental exposure may increase an adult's risk of developing asthma and also may increase the risk of asthma exacerbations. Evaluation of present IAQ levels, exposure characteristics, and the role of exposure to these factors in relation to asthma morbidity is important for improving our understanding, identifying the burden, and for developing and implementing interventions aimed at reducing asthma morbidity.
    Matched MeSH terms: Coal
  17. Zain S, Roslani N, Hashim R, Anuar N, Suja F, Basri N, et al.
    Fossil fuels (petroleum, natural gas and coal) are the main resources for generating electricity. However, they have been major contributors to environmental problems. One potential alternative to explore is the use of microbial fuel cells (MFCs), which generate electricity using microorganisms. MFCs uses catalytic reactions activated by microorganisms to convert energy preserved in the chemical bonds between organic molecules into electrical energy. MFC has the ability to generate electricity during the wastewater treatment process while simultaneously treating the pollutants. This study investigated the potential of using different types of mixed cultures (raw sewage, mixed liquor from the aeration tank & return waste activated sludge) from an activated sludge treatment plant in MFCs for electricity generation and pollutant removals (COD & total kjeldahl nitrogen, TKN). The MFC in this study was designed as a dual-chambered system, in which the chambers were separated by a NafionTM membrane using a mixed culture of wastewater as a biocatalyst. The maximum power density generated using activated sludge was 9.053 mW/cm2, with 26.8% COD removal and 40% TKN removal. It is demonstrated that MFC offers great potential to optimize power generation using mixed cultures of wastewater.
    Matched MeSH terms: Coal
  18. Idris SS, Rahman NA, Ismail K
    Bioresour Technol, 2012 Nov;123:581-91.
    PMID: 22944493 DOI: 10.1016/j.biortech.2012.07.065
    The combustion characteristics of Malaysia oil palm biomass (palm kernel shell (PKS), palm mesocarp fibre (PMF) and empty fruit bunches (EFB)), sub-bituminous coal (Mukah Balingian) and coal/biomass blends via thermogravimetric analysis (TGA) were investigated. Six weight ratios of coal/biomass blends were prepared and oxidised under dynamic conditions from temperature 25 to 1100°C at four heating rates. The thermogravimetric analysis demonstrated that the EFB and PKS evolved additional peak besides drying, devolatilisation and char oxidation steps during combustion. Ignition and burn out temperatures of blends were improved in comparison to coal. No interactions were observed between the coal and biomass during combustion. The apparent activation energy during this process was evaluated using iso-conversional model free kinetics which resulted in highest activation energy during combustion of PKS followed by PMF, EFB and MB coal. Blending oil palm biomass with coal reduces the apparent activation energy value.
    Matched MeSH terms: Coal/analysis*
  19. Ho WW, Ng HK, Gan S
    Bioresour Technol, 2012 Dec;125:158-64.
    PMID: 23026328 DOI: 10.1016/j.biortech.2012.08.099
    Novel heterogeneous catalysts from calcium oxide (CaO)/calcined calcium carbonate (CaCO(3)) loaded onto different palm oil mill boiler ashes were synthesised and used in the transesterification of crude palm oil (CPO) with methanol to yield biodiesel. Catalyst preparation parameters including the type of ash support, the weight percentage of CaO and calcined CaCO(3) loadings, as well as the calcination temperature of CaCO(3) were optimised. The catalyst prepared by loading of 15 wt% calcined CaCO(3) at a fixed temperature of 800°C on fly ash exhibited a maximum oil conversion of 94.48%. Thermogravimetric analysis (TGA) revealed that the CaCO(3) was transformed into CaO at 770°C and interacted well with the ash support, whereas rich CaO, Al(2)O(3) and SiO(2) were identified in the composition using X-ray diffraction (XRD). The fine morphology size (<5 μm) and high surface area (1.719 m(2)/g) of the fly ash-based catalyst rendered it the highest catalytic activity.
    Matched MeSH terms: Coal Ash/chemical synthesis*
  20. Abdullah MM, Jamaludin L, Hussin K, Bnhussain M, Ghazali CM, Ahmad MI
    Int J Mol Sci, 2012;13(4):4388-95.
    PMID: 22605984 DOI: 10.3390/ijms13044388
    This paper presents the results of a study on the effect of temperature on geopolymers manufactured using pozzolanic materials (fly ash). In this paper, we report on our investigation of the performance of porous geopolymers made with fly ash after exposure to temperatures from 600 °C up to 1000 °C. The research methodology consisted of pozzolanic materials (fly ash) synthesized with a mixture of sodium hydroxide and sodium silicate solution as an alkaline activator. Foaming agent solution was added to geopolymer paste. The geopolymer paste samples were cured at 60 °C for one day and the geopolymers samples were sintered from 600 °C to 1000 °C to evaluate strength loss due to thermal damage. We also studied their phase formation and microstructure. The heated geopolymers samples were tested by compressive strength after three days. The results showed that the porous geopolymers exhibited strength increases after temperature exposure.
    Matched MeSH terms: Coal Ash/chemistry*
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links