Physicochemical Properties Of Fly Ash Research Articles

An integrated approach of bioleaching-enhanced electrokinetic remediation of heavy metals from municipal waste incineration fly ash using Acidithiobacillus spp

Introduction: Municipal solid waste (MSW) incineration fly ash is a harmful residue formed during the incineration process. It contains high concentrations of hazardous heavy metals, such as lead, zinc, aluminum, and iron.Methodology: In this study, bioleaching integrated with an electrokinetic approach for heavy metal remediation from MSW incineration fly ash using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans bacteria was tested.Results and discussion: The physicochemical properties of fly ash included a particle size of 26.1 μm, with the presence of heavy metals. A. ferrooxidans and A. thiooxidans produced sulphuric acid (0.0289 M and 0.0352 M) during the proliferation; this acid enhances the bioleaching of heavy metals from fly ash. The results of an integrated approach showed an 85%, 47%, 92%, 85%, 46%, 67% 11%, and 55% removal of the heavy metals K, Na, Ca, Mg, Al, Zn, Pb, and Mg, respectively, in the presence of A. ferrooxidans. Overall, these results evidenced that heavy metals were completely removed from the fly ash using an integrated approach. Therefore, this integrated approach can be used as an effective heavy metal removal method for treating fly ash in MSW.

Adsorption of low-concentration organic pollutants from typical coal-fired power plants by activated carbon injection

Activated carbon (AC) injection was applied to remove the organic pollutants from coal-fired power plants. The total hydrocarbon (THC) concentration in flue gases was 0.512–0.998 mg/m3, aromatic hydrocarbons and oxygenated volatile organic compounds (VOCs) were the major components. With the AC injection (150 mg/m3), the THC was removed by 36.52–46.49%. The mesopores could capture some larger organic molecules and facilitate the intrapore diffusion. Improving the AC injection amount promoted the organic pollutant adsorption, but lowered the AC adsorption capacity. Removal performance of organic pollutants was affected by their physicochemical properties. The removal efficiency for most VOCs was within the range of 15–50%, while that was 45–90% for semi-VOCs. Minor amounts of VOCs achieved high removal efficiency through specific interactions, especially oxygenated VOCs. However, the removal efficiency of the total oxygenated VOCs was lower due to competition adsorption with inorganic components. AC injection had no significant effect on the physicochemical properties of fly ash. This work and results provide a feasible method and reference for the reduction of organic pollutants in coal-fired power plants and other combustion exhaust gases.

Physico-Chemical Properties of Fly Ash and Its Applications in Agriculture Field

The Physical properties of fly ash is depending upon the coal type, boiler type, ash content in coal, combustion method and collector setup. The factor affecting or influencing the physical properties are also responsible for wide variation of chemical properties of fly ash. Two types of fly ash are generated in the thermal power plants; it is also contain micro and macro nutrients, required for growth of plants. Quality of soil is affects the growth of plant, due to low pH of soil plant growth has been affected, it is minimizing with external addition. Fly ash has many micro and macro nutrients with application of fly ash in soil pH of soil becomes controlled.

Assessment of leaf morphological characteristics, phenolics content and metal(loid)s concentrations in Calendula officinalis L. grown on fly ash amended soil

An experiment in pot culture was conducted to analyze the ameliorative impact of different doses of fly ash (FA) in soil on the plant growth performance, total phenolics and flavonoids, and elemental uptake in Calendula officinalis. To determine the growth status of Calendula officinalis, various concentrations of FA and soil [100% garden soil (T1), 20% FA+ 80% garden soil (T2), 40% FA+ 60% garden soil (T3), 60% FA+ 40% garden soil (T4), 80% FA+ 20% garden soil (T5), and 100% FA (T6)] were selected. The physico-chemical properties of FA and soil and elemental concentrations (Ca, Mg, Al, As, Co, Zn, Fe, Mn, and Ni) in all FA treatments were determined. The results showed that under low ratio of FA amendment to the soil (40% FA treatment), the plant growth performance was increased in comparison to plants grown in control (garden soil). However, at high FA doses in soil (60%, 80% and 100% FA treatments), these parameters tend to decrease. Fly ash at 40% concentration did not contain toxic concentrations of these elements such as Co, Zn, Fe, Mn, Ca, Mg, Al, As, and Ni, therefore, beneficial effects of fly ash in terms of improved growth and yield were evident. Furthermore, the leaves showed increasing trend of total phenolic and flavonoid content with increasing FA application up to 60% FA treatment. Therefore, this study showed that 40% FA treatment to the soil is suitable for the growth and yield of Calendula officinalis. Thus, this plant has the phytoremediation potential that can promote cleanup of FA polluted sites for sustainable development.

The effect of mechanical-chemical-brominated modification on physicochemical properties and mercury removal performance of coal-fired by-product

Coal combustion is one of the largest anthropogenic mercury emission source in China, while the coal-fired by-product such as fly ash (FA) and bottom ash (BA) are raw material for making mercury removal adsorbent with low-cost and high efficient and recycling. The mechanical-chemical brominated FA (FA-MC-Br) and BA (BA-MC-Br) were prepared through the omni-directional planetary ball mill. The physicochemical properties of FA, FA-MC-Br, BA, and BA-MC-Br were compared and discussed based on analyses of the X-ray photoelectron spectroscopy, Brunauer-Emmet-Teller, Scanning Electron Microscopy, and mercury temperature programmed desorption, etc. The mercury-removal ability of the four samples was estimated by fixed-bed react system which showed that the mechanical-chemical-brominated modification has no significant effect on the pore structures of FA and BA but obviously reducing their particle sizes and increase the amorphous phase on surface of FA and BA. Besides, the Fe content on the surface of BA was enhanced as well. The Br loading rate of FA-MC-Br and BA-MC-Br is 61.35% and 48.67%, respectively. The mercury removal ability of FA/BA can be significantly improved by the mechanical-chemical-brominated modification. The reaction mechanism and pathways of Hg0 removal by FA-MC-Br and BA-MC-Br can be deduced as the following two parts: (a) HgO is adsorbed and oxidized by the active chemisorbed oxygen and Fe3+ on the surface of samples. (b) HgBr2 is generated by the reaction between the C-Br and Hg0, which follows the Eley-Rideal mechanism.

Studies on the correlation between physicochemical properties of fly ash and its sorption of gas-phase arsenic

ABSTRACTThis study investigated the adsorption behaviors of gas-phase arsenic on four kinds of fly ashes through using a fixed-bed reactor, and analyzed the correlation between sorption of gas-phase arsenic and physicochemical properties of fly ashes at different adsorption temperatures. The results showed that different fly ashes all had an adsorption effect on arsenic. The carbon content and specific surface area had a promoting effect on arsenic adsorption at the low temperature of 400℃, but there was no obvious correlation between arsenic adsorption and the contents of Fe2O3 and CaO. However, it was exactly the opposite at the high temperature of 600℃. So the correlation between physicochemical properties of fly ash and its sorption of arsenic was proved to vary with temperature. It was further revealed that the physical adsorption predominated in temperatures ranging between 200℃ and 400℃, while the chemical adsorption predominated at further higher temperatures. The optimal temperature to maintain a high arsenic capture efficiency should be around 600℃.

Efficacy of carbonated petroleum coke fly ash as supplementary cementitious materials in cement mortars

Abstract In this study, an innovative valorization of petroleum coke fly ash as supplementary cementitious materials in blended cement mortars was investigated. To stabilize and upgrade the properties of fly ash, accelerated carbonation was performed to convert calcium oxide and other calcium-bearing species in fly ash into calcium carbonate. The results indicated the achievable carbonation conversion of fly ash was approximately 40%. The changes in physico-chemical properties of fly ash before and after carbonation also were examined by thermal analysis and Fourier-transform infrared spectroscopy. Several material function tests of blended cement mortars with carbonated fly ash, including workability, strength development and durability, were carried out. We found that the strength of cement mortars blended with carbonated fly ash was 20% higher than that of original Portland cement. A mathematical model on the strength development kinetics was developed to elucidate the relationship between mineral compositions and curing times. The carbonated fly ash could facilitate the hydration reaction in blended cement, as well as accelerating the strength development of blended cement by 28%. This study revealed the possibility of establishing a waste-to-resource supply chain by connecting CO2 mineralization with fly ash valorization as cementitious materials.

The influence of physico-chemical properties of fly ash and CKD on strength generation of high-volume fly ash concrete

This paper presents a laboratory study on the use of cement kiln dust (CKD) as an activator of fly ash when used in high volumes within concrete. Two separate batches of fly ash and CKD were tested to assess the effect of material variability on binder properties and compressive strength gain. Ternary blends of fly ash (55–65%), CEM 1 (30%) and CKD (5–15%) and quaternary blends that included moderate amounts (15–18·5%) of ground granulated blast-furnace slag (GGBS) were prepared. Physico-chemical properties of individual binder materials were compared and concrete compressive strength was measured at 2 d, 7 d and 28 d. Ternary blends of 60% fly ash, 30% cement and 10% CKD resulted in moderate early age and 28 d strength and addition of GGBS enhanced strength significantly due to increased ettringite formation. Particle fineness, water demand and loss on ignition content of fly ash, and calcium oxide and sulfur trioxide content of CKD were found to be the main physico-chemical factors that influence compressive strength gain.

Effects of the physicochemical properties of fly ash on the compressive strength of high-volume fly ash mortar

This study investigated the effect of the physicochemical properties of fly ash, including the particle sizes and chemical composition of the amorphous phase, on the compressive strength of high-volume fly ash mortars in which 50vol.% of ordinary Portland cement was replaced with fly ash. The enhancement in the compressive strength of the high-volume fly ash mortars was observed due to the pozzolanic reaction after 7days of hydration. This was found to depend on a combination of factors, including the content of amorphous SiO2 and Al2O3, amorphous alkalinity, and surface area per volume of fly ash.

Physico-Chemical Properties of Fly Ash Amended Soils and their Impact on Potato Crop

A study was conducted to observe the physico-chemical properties of fly ash amended soils (0%, 5%, 10%, 15%, 20%, 25%, 30%, 40% and 50%) before planting and after harvesting of potato crop and at the same time their impact was also observed on various parameters of potato. As the levels of fly ash were increased, the physico-chemical properties pH, electrical conductivity, cation exchange capacity, water holding capacity, pore space, sulphate and chloride contents, P, K, Mg, Zn, Mn and B were increased before planting. However, N was decreased significantly. After harvesting of potato crop all physico-chemical properties were still greater than control but less than pre-planting of potato, except sulphate, P, K, Zn and Mn which were first decreased upto certain levels and then increased in subsequent levels. N was found nil in all the treatments of fly ash. All the growth, productivity and biochemical parameters of potato were increased upto 25% level of fly ash and were highest at 15% level. After 25% level, all parameters were declined. Thus, 15% soil application of fly ash was found beneficial for the potato crop.

Physicochemical properties and heavy metals leachability of fly ash from coal-fired power plant

The physicochemical properties of fly ash from two kinds of coal-fired power plants were studied. Three aspects were examined: the micro-morphology, the mineral composition and the content of heavy metals. The results show that the fly ash from plants using a circulating fluidized bed are more irregular particles, while the particles from the plants using a pulverized coal-fired boiler are mainly spherical in shape. Quartz and mullite are the main crystalline phases in the ash. Clearly, both the technology and the coal used by a power plant can influence the mineral composition of the ash. The mineral composition of fly ash from a circulating fluidized bed is more complex than that from a pulverized coal-fired boiler. The quantity of elements found in the fly ash is greater than that found in the bottom ash for the same plant. Heavy metals are likely to be enriched in the fly ash. Heavy metal leachability was studied using two leaching methods. The results indicate that most of the heavy metals that leached during either batch leaching or column leaching experiments did not exceed the related maximum concentration standards. But Ni concentrations in the leachates from both batch and column tests exceed the standard. The highest excess rates in both tests were 572% and 497%, which levels might threaten the environment.

Study of ashes from a medical waste incinerator in China: Physical and chemical characteristics on fly ash, ash deposits and bottom ash

In this study, the composition and physicochemical properties of fly ash, air preheater deposits, and bottom ash from a typical medical waste incinerator (MWI) were analyzed. The MWI unit studied consists of a rotary pyrolyser, followed by a vertical cylindrical combustor, featuring an extractor grate above which granular material is fluidized. Fly ash consisted mainly of Ca, Al, Si, Mg, Na, O, C, Cl, and S; the chlorine content in fly ash from this MWI was higher than that in the fly ash generated by a municipal solid waste incinerator (MSWI). Bottom ash consisted mainly of CaCO3, SiO2, and Ca(OH)2, and the major components measured in fly ash and in air preheater ash deposits were CaCO3, CaSO4, NaCl, KCl, SiO2, and Ca2Al2SiO7. The carbon content of fly ash was positively correlated with the specific surface area. The porous structure is much more pronounced in fly ash and deposits than in bottom ash. Ash deposits showed low pH‐values, fly ash and especially bottom ash were found to be basic. High contents of chloride and Ca in the fly ash lowered the ash melting point when compared with that in the fly ash generated by the MSWI. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 496–504, 2013

The effect of sodium silicate and sodium hydroxide on the strength of aggregates made from coal fly ash using the geopolymerisation method

AbstractGeopolymerisation of coal fly ash to produce synthetic aggregates as a potential means of utilising coal combustion by‐product has been investigated. It has been revealed that the geopolymerisation strongly depends on the physicochemical properties of fly ash, the availability of soluble silicates and aluminates, and the concentration of added sodium hydroxide. The presence of sodium hydroxide increases the amount of soluble silicates and aluminates in the mixture through fly ash solubilisation. Solubility tests on various fly ash samples have shown that solubility increases as the concentration of sodium hydroxide in the fly ash increases, which also increases the strength of the resulting geopolymer aggregates. The compression strength of the geopolymer aggregates also increases to a maximum before decreasing again as the amount of sodium silicate is increased. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Fly ash from a Mexican mineral coal I: Mineralogical and chemical characterization

The properties of coal fly ash are strongly dependent on the geological origin and the combustion process of the coal. It is important to characterize regional fly ash in detail to ascertain its potential uses as raw material in the production of high value products. The physicochemical properties of fly ash coming from the “Jose Lopez Portillo” coal-fired power plant, Coahuila, Mexico (MFA), are presented in this work. A detailed study of trace elements, the chemical composition of the amorphous phase, thermal stability and the leaching of contaminant elements under different conditions are included. MFA is composed of mullite, quartz, calcite, magnetite and an amorphous phase. This material contains mainly silica (59.6%), alumina (22.8%) and magnetite (5.6%). Its amorphous phase (78.3%) has a high silica (49.4%) and alumina (14.4%) content. According to its mineralogical and chemical composition, MFA is potentially useful as a raw material for making cement, silica, and alumina, as well as low silica/alumina ratio zeolites. Deleterious elements could be removed during the zeolitization process or with an additional acid treatment. Because of its morphological properties and structural and thermal stability, MFA can be used in thermal isolation and refractory materials and as a support for heterogeneous catalysts.

Application of Solid Ash Based Catalysts in Heterogeneous Catalysis

Solid wastes, fly ash, and bottom ash are generated from coal and biomass combustion. Fly ash is mainly composed of various metal oxides and possesses higher thermal stability. Utilization of fly ash for other industrial applications provides a cost-effective and environmentally friendly way of recycling this solid waste, significantly reducing its environmental effects. On the one hand, due to the higher stability of its major component, aluminosilicates, fly ash could be employed as catalyst support by impregnation of other active components for various reactions. On the other hand, other chemical compounds in fly ash such as Fe2O3 could also provide an active component making fly ash a catalyst for some reactions. In this paper, physicochemical properties of fly ash and its applications for heterogeneous catalysis as a catalyst support or catalyst in a variety of catalytic reactions were reviewed. Fly-ash-supported catalysts have shown good catalytic activities for H2 production, deSO(x), deNO(x), hydrocarbon oxidation,and hydrocracking, which are comparable to commercially used catalysts. As a catalyst itself, fly ash can also be effective for gas-phase oxidation of volatile organic compounds, aqueous-phase oxidation of organics, solid plastic pyrolysis, and solvent-free organic synthesis.

Investigations of the influence of different fly ashes on cement hydration

Investigations of physico-chemical properties of three kinds of fly ash and their influence on cement hydration were performed in this work. Thermal analysis, microcalorimetry, infrared absorption and others were used. It was confirmed that the kind of coal and combustion conditions essentially influence physico-chemical properties of fly ash and in consequence influence cement hydration. Investigated fly ashes show in cement system so-called pozzolanic activity. Fly ash from combustion of brown coal in fluidized furnace revealed better activity compared to other investigated ones. This work is an introduction to more extensive investigation of fly ash activation.

Analyse des molecules organochlorées piegées dans la matrice minérale des REFIOM

Abstract Analysis of the chloroorganic trapped in the mineral matrix of fly ash. Incineration is often considered as the most efficient process for urban waste destruction. Although it is a rather clean technique, it is often suspected to be the source of severe pollutions such as metal pollution or dioxin and furan emissions. In order to reduce hazardous emissions, various operating furnace parameters can be controlled, like gas residence time, flame temperature and excess air flow rate, among others. According to European regulations, incineration fly ash corresponds to class I disposal landfills, which demonstrates that it is considered as a toxic waste. The aim of this work was to develop a non equilibrium plasma process in order to study the behaviour of chloroorganics trapped on fly ash by on-line mass spectrometric analysis. The identification of the desorption of chloroorganics trapped within the mineral matrix presents juridical and scientific aspects. This study shows the existence of chemical reactions between the excited species produced from the plasma and the molecules desorbed from the mineral matrix of fly ash during the plasma treatment through the chemical analysis of the gaseous effluent. Special emphasis was put on the physicochemical properties of fly ash (composition of mineral matrix, particles size…)

Edaphic properties of fly ash from A coal-fired power plant at Kanpur, India

This paper deals with certain physico-chemical properties of fly ash collected from a coal-fired power plant at Kanpur (26° 26′ N latitude and 80° 22′ E longitude), India. Textural analysis reveals that a major fraction of fly ash mass (65%) is composed of silt-sized particles (0·02 to 0·002 mm). Sand-sized particles (2·0 to 0·02 mm) represented 25%, while clay-sized particles (<0·002 mm) represented only 10%. The bulk density and optimum moisture content of freshly collected fly ash samples were measured, being 1·02 g cm −3 and 2·1%, respectively. Water extracts from fly ash were alkaline and contained excessive amounts of soluble salts. Samples of each fraction of fly ash (sand, silt and clay) were analysed for concentrations of four macro-elements (N, P, K and Ca) and four trace elements (B, Cu, Mn and Zn). Except for N, fly ash contained higher concentrations of all elements than normally found in soil.