Fly Ash Extract Research Articles

Modern Rare Earth Imprinted Membranes for the Recovery of Rare Earth Metal Ions from Coal Fly Ash Extracts.

The need to identify secondary sources of REEs and their recovery has led to the search for new methods and materials. In this study, a novel type of ion-imprinted adsorption membranes based on modified chitosan was synthesized. Their application for the recovery of chosen REEs from synthetic coal fly ash extracts was analyzed. The examined membranes were analyzed in terms of adsorption kinetics, isotherms, selectivity, reuse, and their separation abilities. The experimental data obtained were analyzed with two applications, namely, REE 2.0 and REE_isotherm. It was found that the adsorption of Nd3+ and Y3+ ions in the obtained membranes took place according to the chemisorption mechanism and was significantly controlled by film diffusion. The binding sites on the adsorbent surface were uniformly distributed; the examined ions showed the features of regular monolayer adsorption; and the adsorbents showed a strong affinity to the REE ions. The high values of Kd (900-1472.8 mL/g) demonstrate their high efficiency in the recovery of REEs. After five subsequent adsorption-desorption processes, approximately 85% of the value of one cycle was reached. The synthesized membranes showed a high rejection of the matrix components (Na, Mg, Ca, Al, Fe, and Si) in the extracts of the coal fly ashes, and the retention ratio for these Nd and Y ions was 90.11% and 80.95%, respectively.

Pemanfaatan Limbah Fly Ash Sebagai Koagulan Dalam Pengolahan Air Melalui Ekstraksi Aluminium Dan Besi Menggunakan Metode Kalsinasi – Pengasaman

The process of burning coal by PLTU produces large amounts of fly ash waste that has the potential to pollute the environment if not handled properly. Various kinds of research have been carried out to deal with fly ash waste, one of which is to make fly ash a coagulant material because it has a dominant aluminum and iron content. The conviction of the use of fly ash as a coagulant aims to determine the highest recovery presentation of aluminum and iron using HCl and H2SO4 solvents with variations in concentrations of 6%, 8%, and 10%, variations in extraction time of 2 hours, 4 hours, and 6 hours, and determine the rate of decrease in turbidity using the resulting coagulants. This study began with the preparation and characterization of fly ash samples using X-Ray Fluorescence (XRF), then the reparated sample mixed with Na2CO3 4 M is then calcined at a temperature of 950 ⁰C to be then extracted using HCl and H2SO4. The results showed that the highest percentage of extracted aluminum and iron recovery used 10% HCl for 6 hours ie 97.91% and 96.01%, and used 10% H2SO4% for 6 hours, 99.66% and 97.79%. Increasing solvent concentrations and extraction times cause increased concentrations of aluminum and extracted iron. Coagulant quality testing of fly ash using the jar test method, obtained the result that the coagulant results from the extraction of fly ash with HCl and H2SO4 solvents at 10% concentration% with an extraction time of 6 hours is the best coagulant that can reduce the value of turbidity to 0.61 NTU and 0.74 NTU.

Concentrations, Speciation, and Potential Release of Hazardous Heavy Metals from the Solid Combustion Residues of Coal-Fired Power Plants.

Hazardous heavy metal-laden coal combustion byproducts exposed to precipitation or surface/groundwater are of environmental concern. This study analyzed fly ash (FA) and desulfurization gypsum (FGD gypsum) samples obtained from 16 coal-fired power plants in Guizhou Province, China. A combination of field and laboratory studies was used to investigate the binding forms of lead (Pb), cadmium (Cd), and chromium (Cr) and their leaching characteristics under natural storage conditions. The results showed that there were significant proportions of residual states of these elements in FA (84–99% for Pb, 83–91% for Cd, and 73–97% for Cr), indicating a lack of migration to other environmental media. FGD gypsum contained high proportions of metals in migratable states, but the environmental risks were low due to their very low concentrations. The release of Pb, Cd, and Cr from FA and FGD gypsum into extracts varied according to pH. This is related to the form of each element in the solid and the series of reactions that occurs during the leaching process. However, aside from Cr in FA, all heavy metals in FA and FGD gypsum samples were present in concentrations below the relevant standards for landfill leachate, indicating very low release rates. The Cr levels (206–273 μg/L) in some of the FA extracts were higher than the limits for water pollution from domestic landfill, indicating that Cr in FA poses a leaching risk. The results of field leachate sampling and indoor simulated rainfall experiments further validated these findings, indicating that the release of Cr from stockpiled coal FA is a cause for concern.

Synthesis of synthetic amorphous silica powder from palm oil mill fly ash extract by carbon dioxide impregnation

Palm oil mill fly ash (POMFA) is rich in amorphous silica and can be extracted by sodium hydroxide solvent. This work aims to synthesize synthetic amorphous (SAS) powder silica that has mesoporous pores and a high specific surface area. The sol–gel precipitation process was applied by CO 2 impregnation and polyethylene glycol (PEG) 400 was used as the surfactant to obtain the synthetic silica powder from the extract. A temperature-controlled 1000 cm 3 glass precipitator equipped with a stirrer was used for the precipitation process. The extracted silica was mixed with PEG at pre-determine concentration, and 500 cm 3 of the mixed liquid was put in the precipitator and stirred at 1000 RPM. The carbon dioxide impregnated at a flow rate of 100 cm 3 min −1 to destabilize the silica extract. The study was done by using PEG-400 as a dispersant to improve the specific surface area of the obtained precipitated silica. The temperature, precipitation time, and the PEG concentration were varied to study their effect on SAS yield. The optimum SAS yield of 80.01% was obtained at a temperature of 70 °C, time of 90 min, and a PEG concentration of 5%. The characteristics of the SAS obtained are SSA of 198.55 m 2 g −1 , volume pore of 0.289 cm 3 g −1 , and pore diameter of 5.32 nm.

Magnetic Fly Ash as a Chronological Marker in Post-Settlement Alluvial and Lacustrine Sediment: Examples from North Carolina and Illinois

Fly ash consists of mainly silt-size spherules that form during high-temperature coal combustion, such as in steam locomotives and coal-burning power plants. In the eastern USA, fly ash was distributed across the landscape atmospherically beginning in the late 19th century, peaking in the mid-20th century, and decreasing sharply with implementation of late 20th century particulate pollution controls. Although atmospheric deposition is limited today, fly ash particles continue to be resedimented into alluvial and lacustrine deposits from upland soil erosion and failure of fly ash storage ponds. Magnetic fly ash is easily extracted and identified microscopically, allowing for a simple and reproducible method for identifying post-1850 CE (Common Era) alluvium and lacustrine sediment. In the North Carolina Piedmont, magnetic fly ash was identified within the upper 50 cm at each of eight alluvial sites and one former milldam site. Extracted fly ash spherules have a magnetite or maghemite composition, with substitutions of Al, Si, Ca, and Ti, and range from 3–125 µm in diameter (mainly 10–45 µm). Based on the presence of fly ash, post-1850 alluvial deposits are 15–45 cm thick in central North Carolina river valleys (<0.5 km wide), ~60% thinner than in central Illinois valleys of similar width. Slower sedimentation rates in North Carolina watersheds are likely a result of a less agricultural land and less erodible (more clayey) soils. Artificial reservoirs (Lake Decatur, IL) and milldams (Betty’s Mill, NC), provide chronological tests for the fly ash method and high-resolution records of anthropogenic change. In cores of Lake Decatur sediments, changes in fly ash content appear related to decadal-scale variations in annual rainfall (and runoff), calcite precipitation, land-use changes, and/or lake history, superimposed on longer-term trends in particulate pollution.

Arsenic and selenium distribution and speciation in coal and coal combustion by-products from coal-fired power plants

This study investigated arsenic (As) and selenium (Se) distribution and speciation in coal and the burning by-products (fly ash and gypsum) in five coal-fired power plants in China. Total concentrations of As and Se in coal varied significantly among different power plants, but most of them were below the average As and Se content in Chinese coal. The concentrations of As and Se in fly ash were much higher than that in coal. Total As contents in four gypsum samples were lower than that in coal, while Se contents in four gypsum samples were much higher than that in coal. The species of inorganic As (AsIII and AsV) and Se (SeIV and SeVI) were determined by high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry after solvent extraction. The extraction efficiencies of As and Se in coal were low, but a considerable amount of As and Se in fly ash and gypsum can be extracted, showing that elements As and Se were easily leached from the burning by-products. Speciation analysis indicated that Se was mostly present as SeIV in all the fly ash and gypsum extracts, and AsV was the dominating species in coal and fly ash extracts. In contrast, AsIII, much more toxic than AsV, was mainly detected in gypsum. Large amounts of coal-fired by-products are produced every year, most of which end up in landfills or stockpiled in the open areas. Our results suggest that the proper disposal of coal-fired solid wastes is urgently demanded.

Preservation of geochemical markers during co-combustion of hard coal and various domestic waste materials

Combustion of domestic waste for heating purposes in non-adapted furnaces is a common environmental problem all over the world since it leads to significant emission of harmful substances to the atmosphere. In this project fly and bottom ash from hard coal and domestic waste co-combustion were investigated on the occurrence and distribution of geochemical markers, polycyclic aromatic hydrocarbons (PAHs), and their alkyl derivatives. Hard coal with a domestic waste admixture (paper, ethylene propylene diene rubber, tire rubber, polyethylene, polyvinyl chloride) was combusted in a certified domestic central heating furnace equipped with a control and measurement system. Fly ash was collected on glass microfiber filters inside the flue gas chimney. Raw fuels, fly and bottom ash extracts were analyzed with gas chromatography–mass spectrometry (GC–MS). Geochemical markers survived the coal/domestic waste combustion and can be identified despite the presence of other organic compounds derived from domestic waste thermal decay. The highest changes in distribution and values of geochemical ratios concern light-weight compounds, i.e. lighter n-alkanes and acyclic isoprenoids (pristane and phytane), with distinct differences between fly and bottom ash. n-Alkanes expulsion significantly decreased values of Pr/n-C17 and Ph/n-C18 ratios. Due to their high molecular weight pentacyclic triterpanes mostly retained their original distributions; however, some shifts in values of their thermal maturity ratios occurred due to artificial maturation of organic matter under the heat of combustion. PAHs diagnostic ratios showed variable utility in the indication of domestic waste admixture to hard coal combusted. The highest sensitivity was found for BaP/BghiP, MPI-1, and MPI-3 whereas Fl/(Fl + Py) rather pointed out at hard coal dominating in the fuel mixture. The addition of EPDM and tires significantly worsened the quality of combustion, which is reflected in high extract yields and the retained hard coal geochemical features such as the Pr/Ph value closest to the raw coal value.

Municipal Solid Waste as Secondary Resource: Selectively Separating Cu(II) from Highly Saline Fly Ash Extracts by Polymer-Assisted Ultrafiltration

Urban mining from fly ash resulting from municipal solid waste incineration (MSWI) is becoming more and more important due to the increasing scarcity of supply-critical metals. Metal extraction from acid fly ash leaching has already been established. In this context selective Cu recovery is still a challenge. Therefore, our purpose was the separation of Cu(II) from MSWI fly ash extracts by polymer-assisted ultrafiltration (PAUF). We investigated three polyethyleneimines (PEIs) with regard to metal retention, Cu(II) selectivity, Cu(II) loading capacity, and the viscosity of the PEI containing solutions. A demanding challenge was the highly complex matrix of the fly ash extracts, which contain up to 16 interfering metal ions in high concentrations and a chloride content of 60 g L−1. Overcoming that, Cu(II) was selectively enriched and separated from real fly ash extract at pH 3.0. At pH 1.0, a PEI-free Cu(II) concentrate was obtained and PEIs could be regenerated for reuse in further separation cycles. The PAUF conditions developed at laboratory scale were successfully transferred to pilot scale, and hyperbranched PEI (HB-PEI) was found to be the most suitable reagent for PAUF in a technical scale. Moreover, HB-PEI enables photometric control of the Cu(II) enrichment.

Cr(VI) Leached from Lignite Fly Ash—Assessment of Groundwater Contamination Risk

The leaching of Cr(VI) from lignite fly ash was investigated by means of experimental standards and theoretical simulations. Two lignite fly ash samples with different calcium oxide concentration were examined. Acid extraction of fly ash and batch leaching tests were performed at various liquid (water) to solid (fly ash) ratios (L/S) for the estimation of Cr(VI) leaching rate. The mobility of Cr(VI) in soil and soil’s hydraulic conductivity at different temperatures was also examined. The results indicate that chromium in fly ash occurs mainly in its trivalent form and that Cr(VI) can be leached, but at lower degree. Along with Cr(VI), the strong reducing agent Fe(II) is also leached. A portion of the Cr(VI) is readily leached, while several hours are needed for reaching Cr(VI) equilibrium concentration in leachate. The fly ash hydraulic conductivity is greatly affected by its pozzolanic characteristics, decreasing from around 10 mm/h (2.78 × 10−6 m/s) to values lower than 1 mm/h (2.78 × 10−7 m/s) in few hours. In continuous leaching tests, relatively low Cr(VI) concentrations (< 20 μg/L) were detected, while in batch leaching tests with higher water/fly ash contact time, leachate Cr(VI) concentrations up to 700 μg/L were detected depending on the applied L/S ratio. However, for low L/S (0.5–1) ratios, no leachate was obtained. Theoretical calculations were performed in order to estimate the L/S ratios at real conditions (by taking into account the volume and the surface of an ash disposal, the density of ash, the hydraulic conductivity of ash, rainfall rate, and rainfall duration). It was found that in real conditions, high L/S can be obtained only when various specific conditions are fulfilled. Experiments with soil showed that only a small portion (approximately 4%) of the leached Cr(VI) can pass through a relatively thin (12–15 cm) layer of soil, even at low temperatures. Based on the experimental results and the groundwater and surface water quality data of a studied basin, a low contamination risk due to Cr(VI) leaching from lignite fly ash is assessed.

Stabilization of heavy metals in MSWI fly ash with a novel dithiocarboxylate-functionalized polyaminoamide dendrimer

A novel heavy metal chelating agent, dithiocarboxylate-functionalized polyaminoamide dendrimer (PAMAM-0G-DTC), was evaluated for the stabilization of heavy metals from municipal solids waste incineration (MSWI) fly ash. PAMAM-0G-DTC achieved overall stabilization performance at a lower dosage (3% w/w) and a wider pH range (2–13) compared to conventional chelating agents such as sodium dimethyl dithiocarbamate (SDD) and dithiocarboxylate-functionalized tetraethylenepentamine (TEPA-DTC). The leaching toxicity of Pb and Cd in the MSWI fly ash by PAMAM-0G-DTC stabilization met the landfill requirements but could not be achieved by SDD and TEPA-DTC even at a 10 wt% concentration. Sequential chemical extraction of fly ash before and after stabilization shows that PAMAM-0G-DTC can be combined with active heavy metals in water-soluble, interchangeable, and carbonate states to form more stable heavy metals in organic and residual states. Mechanistic studies show that multiple PAMAM-0G-DTC molecules can combine with multiple heavy metals to form three-dimensional network-like super-molecular compounds with an infinite extension of space size. This makes the heavy metals more stable and embedded in the network-like super-molecular structure, thus minimizing the potential risk of leaching. Overall, by forming more geochemically stable phases, the treatment of fly ash with PAMAM-0G-DTC has a strong ability to reduce the toxic leaching of heavy metals at a lower dosage and suppress the risk of secondary pollution in a landfill at a wide range of pH values (2–13).

Speciation of Trivalent/Hexavalent Chromium in Fly-ash Extracts by Solid-phase Extraction/Atomic Absorption Spectrometry Using a Chelate Resin Treated with Iron(III) Nitrate

Speciation of Trivalent/Hexavalent Chromium in Fly-ash Extracts by Solid-phase Extraction/Atomic Absorption Spectrometry Using a Chelate Resin Treated with Iron(III) Nitrate

Synthesis and characterization of pure phase zeolite 4A from coal fly ash

This study was aimed at the synthesis of pure phase zeolite 4A from coal fly ash sourced from Nishat power plant in the Punjab province of Pakistan. Analysis of fly ash (FA) demonstrated that it can be used to produce low silicate type zeolites specifically zeolite 4A due to its Si/Al molar ratio of ∼2. The current investigation emphasized on the addition of induction time (before and after crystallization) to the fly ash extract of Si-Al-Na species that was extracted from fly ash. The induction time helped in catalysing primary and secondary gel formation during the synthesis leading to controlled formation of single phase with high crystallinity and small crystallite size. The physiochemical investigations of synthetic zeolite 4A by using various analytical techniques made the proposed process justified on comparison with commercial zeolite 4A. The X-Ray Diffraction (XRD) analysis for synthesize zeolite 4A confirmed only one crystallographic phase and small crystallite size with 82% crystallinity compared to reference zeolite with 75% crystallinity. Fourier-Transform Infrared spectroscopy (FTIR) spectra revealed the structural aspects of synthesis and reference zeolite by indicating the presence of identical structural units with same height and width of peaks. Morphological analysis by Scanning Electron Microscope (SEM) showed a well-defined cubic shape of synthesis zeolitic crystals. Surface area analyses by Brunauer–Emmett–Teller (BET) showed that synthesized zeolite possessed 122 m2/g surface area that is 3 times higher than reference zeolite of 36.3 m2/g. The synthesized zeolite was also found to have smaller particle size than reference zeolite. Thermal stability comparison of both zeolites was studied by non-isothermal Thermo Gravimetric Analysis-Differential Thermal Analysis (TGA-DTA) thermograms from 25 to 800 °C temperature and both the samples were found to be stable at 800 °C.

Dynamic hydrothermal synthesis of xonotlite fibers by alkali silica extraction of fly ash

The silica leached from coal fly ash using alkali, via the hydrothermal method, can be used as the raw material for the synthesis of xonotlite fibers through the hydrothermal synthesis method. This investigation was made to examine how the fly ash desilicated liquid influences the crystal growth and microstructure of xonotlite fibers. The obtained samples were characterized by X-ray diffraction and scanning electron microscope techniques to investigate their mineralogical composition and morphological characteristics. The results indicated that the pure desilication liquid leached from coal fly ash could be used to prepare xonotlite fibers. Xonotlite fibers with single crystal characteristics and large aspect ratio of 100–400 were successfully fabricated from fly ash desilication liquid, which is used as the silica material, at 240°C for 6 h.

Application of sequential extraction and hydrothermal treatment for characterization and enrichment of rare earth elements from coal fly ash

Rare earth elements (REE) play a critical role in the global economy. The concern about the REE supply challenge has stimulated global interest in recovering REE from alternative non-conventional REE sources such as coal fly ash. In this paper, sequential extraction, physical separations and hydrothermal alkaline treatment were explored for characterization and enrichment of REE from coal fly ash. Seven-step sequential extraction of coal fly ash has demonstrated that 86.1% of total REE were associated with the glassy phase of the fly ash, with the remaining REE mainly distributed in the organic and sulfides phase (8.3%), the exchangeable phase (3.7%), and the carbonates phase (1.5%). A process combining physical separations, namely, particle size separation and magnetic separation, and hydrothermal alkaline treatment was proposed for enrichment of REE from coal fly ash. The optimal hydrothermal alkaline treatment condition was determined. It was demonstrated that NaOH concentration, solid-to-liquid ratio, temperature, and reaction duration had significant influence on ash dissolution in NaOH solution. Grinding could also enhance ash dissolution during subsequent hydrothermal alkaline treatment. REE were enriched from coal fly ash from 325 mg/kg to 877 mg/kg via the proposed process under optimal hydrothermal alkaline treatment conditions.

Effects of calcium oxide and ferric oxide on the process of alumina extraction of coal fly ash activated by sodium carbonate

The efficient utilization of aluminum and silicon resources simultaneously is expected to reach by the process of alumina extraction from coal fly ash via Na2CO3 activation-acid leaching method. The impurities in the system, CaO and Fe2O3 especially, would affect the process. The effects of CaO and Fe2O3 on the “Na2CO3 activation-acid leaching” process were studied systematically using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and Inductively Coupled Plasma (ICP). The possible influencing mechanisms in the process were proposed. The results showed that soda-nepheline ((Na2O)0.33NaAlSiO4) was the main product in FA-Na2CO3 system. The presence of CaO, however, would react with Al2O3 and SiO2 and form Ca3Al2O6 and Ca2SiO4. The presence of Fe2O3 would limit the formation of (Na2O)0.33NaAlSiO4 by capturing small amount of Na2O to form Na2Fe2O4, leading to the formation of NaAlSiO4. Overall, the dissolution of Al2O3 was predominately affected by CaO, but less by Fe2O3. The compositions of Al-extracted residue would not be significantly affected by merely increasing the amount of CaO or Fe2O3. In the presence of CaO and Fe2O3 together in the FA-Na2CO3 system, an insoluble Ca2Fe2O4 was formed preferentially during the calcination process, and therefore decreased the content of SiO2 in Al-extracted residue. The further study showed that both the dissolution of Al2O3 and the content of SiO2 in Al-extracted residue could reach >90% if the contents of CaO and Fe2O3 were controlled within 6.33% and 15.27% respectively, by which the synergistically utilization of Al2O3 and SiO2 could be realized.

Conversion of South African Coal Fly Ash into High-Purity ZSM-5 Zeolite without Additional Source of Silica or Alumina and Its Application as a Methanol-to-Olefins Catalyst

Characteristics of ZSM-5 synthesized from H2SO4-treated coal fly ash and fused coal fly ash extracts are compared in this study. In the synthesis process, fused coal fly ash extract (without an additional silica source) was used in the synthesis of ZSM-5. The effect of the structure-directing agent (tetrapropylammonium bromide, 1,6-hexanediamine or 1-propylamine) on the properties and methanol-to-olefins (MTO) effectiveness of the fly ash-based ZSM-5 was also investigated. A pure ZSM-5 synthesized from the fused coal fly ash extract led to a methanol conversion higher than 90% after 5 h on stream. The template 1,6-hexanediamine led to the synthesis of the most stable fly ash-based catalyst keeping a 44% methanol conversion after 24 h on stream.

An assessment of different extraction and quantification methods of penta- and hexa-chlorobenzene from SRF fly-ash

Highly chlorinated benzenes, produced in the presence of organic matter and chlorine, are considered PCDD/Fs precursors, and are used as cost and time convenient substitute indicators for the indirect measurement of the latter. In this study penta- and hexa-chlorobenzene are quantified for the determination of the organochloride load of fly ash from solid recovered fuel incineration. Some of the chlorobenzenes are formed under ‘de novo’ conditions, through heterogeneous (ash particles/flue gases) reactions and are therefore deeply incorporated within fly ash. Accelerated solvent extraction (ASE) and ultrasonic solvent extraction (USE), along with the equivalent clean-up methods suggested by literature were compared to traditional Soxhlet. The extraction efficiencies achieved were 83 ± 7.5% for Soxhlet, 111 ± 19% for PFE, and 67 ± 17% for ultrasonication. Soxhlet extraction and clean-up through a multilayer silica gel column gave more precise results compared to the other sample preparation methods. Furthermore, performance comparison of gas chromatography fitted with either a mass spectrometer operated in single ion monitoring mode (GC-MS-SIM), or electron capture detector (GC- ECD) highlighted that ECD can be used for measuring chlorobenzenes traces down to 0.21 ng g−1, when the equivalent LOQ for MS-SIM was 3.26 ng g−1. The results further suggest that ECD can provide better peak integration than MS-SIM in the detection of chlorobenzenes in fly ash extracts, due to the detector's sensitivity to halogenated compounds.

Identifikacija PAHova u pepelu poljoprivredne biomase metodom GC/MS

Biomass is considered as the source of energy with the highest perspective both in terms of reducing greenhouse gas emission and limited resources of fossil fuels. Therefore, in the last few years, constantly working on developing and improving of combustion technology has been of great significance, and that would enable the use of agricultural biomass beams of different sizes and shapes as a renewable fuel for energy production. In Serbia, biomass has huge potential, many types and forms of biomass are available and can be obtained from various sources. On the other hand, such diversity of biomass makes it very complex fuel for producing energy. In the Agricultural Corporation PKB, the technology of cigarette combustion has been applied for nearly a decade and it is used for greenhouse heating. Considering that the law will regulate the monitoring and control of the content of volatile and semi-volatile organic compounds, such as polycyclic aromatic hydrocarbons, emitted during combustion of biomass, it is necessary to develop a method for their identification. GC/MS method was used for separation and detection of PAHs in fly ash extracts of agricultural biomass. It was found that of the 16 priority PAHs, only the last three (indeno (1,2,3-c, d) pyrene, dibenzo (a, h) anthracene and benzo (g, h, i) perylene) were not detected in cyclone fly ash.

Influence of aluminium source on the crystal structure and framework coordination of Al and Si in fly ash-based zeolite NaA

In this study zeolite NaA with different crystal sizes and % crystallinity was prepared from a clear solution extract of fused fly ash. Sodium aluminate or aluminium hydroxide was used to adjust the aluminium content in the fused fly ash extract and hence adjust the Si/Al ratio of the various synthesis molar regimes for the synthesis of zeolite NaA. Each molar regime was hydrothermally treated for 3h at 100°C. Chemical, mineralogical, morphological and structural composition of the synthesized products was determined using XRF, laser ablation ICP-MS, XRD, SEM and 29Si and 27Al NMR. This study showed that the variation of Si/Al ratio of the synthesis mixture (0.27 to 0.80) allowed control of zeolite NaA crystal/sizes that ranged from 0.67 to 3.18μm. The decrease in Si/Al ratio of the synthesis mixture was proportional to the crystal size (μm) and the 29Si NMR peak width and area of the synthesized zeolite NaA. The increase in crystallinity and decreases in crystal size caused the 29Si NMR peak width to be narrower as the peak area reduces. Interestingly, the Si/Al ratio of the synthesis mixture was inversely proportional to the crystallinity of zeolite NaA when Na-aluminate was used as Al source. The effect of Al source was also noticed by the appearance of a small additional distorted tetrahedral Al peak between 15 and 17ppm (27Al NMR) when Al-hydroxide was added to fused fly ash extract.

Fly ash effect on hatching, mortality and penetration of root-knot nematode (Meloidogyne incognita) in pumpkin roots

An experiment was conducted to observe the effect of fly ash on hatching, mortality and penetration of root-knot nematode (Meloidogyne incognita) in pumpkin roots. For hatching experiment different fly ash-extract concentrations (5, 10, 20, 30, 40, and 50%) were prepared. Hatching was significantly reduced in all concentrations, maximum being at 50% concentration. The mortality (%) of juveniles was observed in 1, 2, 3, 4, 5, 6 and 7th days with different levels (5, 10, 20, 30, 40 and 50 %) of fly ash-extract. All the levels were found harmful to juveniles. As the level was increased, the killing percentage of juveniles was also increased. Highest mortality was observed in 7th day with 50% level.For the penetration experiment, fly ash was mixed with soil to prepare different concentrations (5, 10, 20, 30, 40, and 50%). Seeds of pumpkin were grown in coffee cups filled with different mixtures. At two leaf stage, seedlings were inoculated with 2000 larvae. The penetrated larvae in roots were observed after 1, 2, 3, 4, 5, 6 and 7 days. Root penetration was found inversely proportional to concentration. Significant results in the suppression of nematode penetration were noted up to 40% concentration. However, none of the juveniles was penetrated at 50% concentration.International Journal of Environment Vol.5(3) 2016, pp.66-73