Industrial Waste Fly Ash Research Articles

Cadmium Removal from Contaminated Water Using Polyelectrolyte-Coated Industrial Waste Fly Ash.

Fly ash (FA) is a major industrial waste generated from power stations that add extra cost for proper disposal. Recent research efforts have consequently focused on developing ways to make use of FA in environmentally sound applications. This study, therefore, investigates the potential ability of raw fly ash (RFA) and polyelectrolyte-coated fly ash (PEFA) to remove cadmium (Cd) from polluted water. Using layer-by-layer approach, functionalized fly ash was coated with 20 layers from 0.03% (v/v) of cationic poly(diallyldimethylammonium chloride) (PDADMAC) and anionic polystyrene sulfonate (PSS) solutions. Both surface morphology and chemical composition of the adsorbent (PEFA) were characterized using Field-Emission Scanning Electron Microscope (FE-SEM), X-Ray Diffraction (XRD), Fourier-Transform Infrared (FTIR), and X-Ray Fluorescence (XRF) techniques. The effects of pH, adsorbent dosage, contact time, initial contaminant concentration, and mixing rate of the adsorption of Cd were also studied in batch mode experiments. Results of the study revealed that a 4.0 g/L dosage of PEFA removed around 99% of 2.0 mg/L of Cd in 15 min at 150 rpm compared to only 27% Cd removal achieved by RFA under the same conditions. Results also showed that adsorption by PEFA followed both Langmuir and Freundlich models with correlation coefficients of 98% and 99%, respectively.

Poly(vinyl butyral) -polyaniline-magnetically functionalized fly ash cenosphere composite film for electromagnetic interference shielding

The present study is about the electromagnetic interference (EMI) shielding effectiveness of polymer magnetically functionalized industrial waste fly ash cenosphere (FAC, hollow microspheres) composite film. The size range of the used FAC was 5-70 mu m (average size similar to 45 mu m) and these were Co/Ni coated chemically and efficiently functionalized by in situ synthesis of polyaniline under nitrogen at -30 +/- 2 degrees C. Poly(vinyl butyral) polyaniline-Co/Ni-FAC composite films (PVB-PANI-Ni/Co-FAC) were prepared by solution processing and electromagnetic interference (EMI) shielding property was investigated in the J-band (5.8-8.2 GHz) and X-band (8.2-12.4 GHz) frequency range. The most effective EMI shielding effectiveness (SE) of similar to 20 +/- 1 dB and similar to 23 +/- 1 dB was obtained for PVB-PANI-Ni-FAC (PVBPNC) film (thickness 259 +/- 2 mu m) in the frequency range 5.8-8.2 GHz and 8.2-12.4 GHz respectively, whereas EMI SE of PVB-PANI film (268 +/- 2 mu m) was found to be similar to 11 +/- 0.52 dB and similar to 13 +/- 1 dB. For all the composite films, majority of EMI shielding occurs due to the absorption. The obtained EMI shielding due to absorption (SEA) of PVBPNC film was found to be similar to 17 +/- 1 dB and similar to 20 +/- 0.53 dB for J-band and X-band, respectively. In contrast to PVB-PANI (PVBP) film the SEA of PVB-PANI-Co/Ni-FAC composite film was found to increase with frequency. This behaviour of these composite films is exchanged as due to the increase of frequency dependent conductivity and EM attenuation constant. The dielectric studies, also carried out in this investigation, calculated complex permittivity (epsilon* = epsilon' - i epsilon `'), and complex permeability (mu* = mu' - i mu `') values show the excellent electrical (epsilon `') and magnetic loss (mu `') for enhancing the EMI shielding due to absorption. (C) 2016 Elsevier Ltd. All rights reserved.

Development of Novel Natural Composites with Fly Ash Reinforcements and Investigation of their Tensile Properties

Increasing demand for special materials leads to new inventions. One of the most promising inventions is the concept of composites. Natural fibers have the potential as a reinforcing material as an alternative to the use of glass, carbon and other synthetic fibers in automotive industries. Among various natural fibers, Kenaf is a widely used fiber due to its easy availability, low density, low production cost and satisfactory mechanical properties. To enhance the mechanical properties of natural fibre composites, strengthening of the matrix and fibre is very much essential. A prospective reinforcement in this regard is fly ash, which is abundantly available as a waste product from thermal power plants. In this paper, a new novel natural composite with epoxy as a resin and reinforcing both bio waste (Kenaf) and industrial waste (Fly ash) has been developed. All the laminates were prepared with a total of 4 plies. Laminates without fly ash filler were also fabricated for comparison purpose. A hand lay-up method was used for the fabrication of composites and was tested as per ASTM standards for evaluation of tensile properties. The effect of fly ash weight percentage (5, 10, 15% wt.) on tensile properties was studied experimentally. Due to the incorporation of fly ash fillers into the kenaf fiber composites, there is considerable improvement in the mechanical properties. Overall results supported the effective utilization of natural composites for automotive applications.

Superior photocatalytic, electrocatalytic, and self-cleaning applications of Fly ash supported ZnO nanorods

Ever growing research on modified semiconductor oxides made a significant progress in catalytic functional materials. In this article, we report the modification of ZnO photocatalyst by a simple hydrothermal decomposition method utilizing the cheaply available industrial waste fly ash. This modified Fly ash-ZnO photocatalyst was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), high resolution transmission electron microscopy (HR-TEM), Atomic force microscopy (AFM), photoluminescence spectroscopy (PL) and diffuse reflectance spectroscopy (DRS). The XRD pattern indicates the presence of fly ash components and the hexagonal wurtzite structured ZnO. TEM images reveal well defined nanorod like structure. Reduction of photoluminescence intensity of Fly ash-ZnO at 418 nm, when compared to, prepared ZnO, indicates the suppression of recombination of the photogenerated electron–hole pair by loaded Fly ash on ZnO. Fly ash-ZnO exhibits enhanced photocatalytic activity for the degradation of azo dyes Reactive Orange 4, Rhodamine-B and Trypan Blue. This catalyst shows higher electrocatalytic activity than ZnO in the oxidation of methanol. Significant hydrophobicity of Fly ash-ZnO reveals its self cleaning property.

SHS production of heat-shield materials from minerals and residual products: Influence of preliminary mechanochemical treatment and modifying agents

We report on preparation of porous refractory ceramics from natural quartz sand and industrial wastes (fly ash and wastes of concrete production) by SHS in a mode of thermal explosion with preliminary mechanochemical treatment of charge mixtures in the presence of carbonaceous modifying agents (activated carbon and polystyrene). The Al2O3–AlN-based composite synthesized in optimized conditions exhibited low thermal conductivity [0.185–0.228 W/(m K)], finely porous structure, and high compression strength (30–96 MPa).

Microstructure and wear characterization of aluminum matrix composites reinforced with industrial waste fly ash particulates synthesized by friction stir processing

Fly ash (FA) is a waste product of coal combustion in thermal power plants which is available in massive quantities all over the world causing land pollution. This paper reports the characterization of AA6061 aluminum matrix composites (AMCs) reinforced with FA particles synthesized using friction stir processing (FSP). The volume fraction of FA particles was varied from 0 to 18 in steps of 6. The prepared AMCs were characterized using optical microscopy (OM), scanning electron microscopy (SEM) and electron backscattered diagram (EBSD). The wear rate was estimated using a pin-on-disc wear apparatus. FA particles were observed to be distributed homogeneously in the AMC irrespective of the location within the stir zone. The EBSD micrographs revealed remarkable grain refinement in the AMC. The incorporation of FA particles enhanced the microhardness and wear resistance of the AMC. The strengthening mechanisms of the AMC were discussed and correlated to the observed microstructures. The wear mechanisms were identified by characterizing the wear debris and worn surfaces.

Designing Of LDPE/fly Ash/ Expanded Graphite Sheet For Electrostatic Charge Dissipation Application

The paper aims to explore the utilization of industrial waste fly ash as a filler material into low density polyethylene (LDPE) polymer matrix with / without expanded graphite to optimize the electrostatic charge dissipative (ESD) properties as injection molded sheets. Homogeneous mixing of composite mixture has been carried out in a single screw extruder via melt blending and designed to sheet form by using an injection molding machine. The mechanical and thermal properties of the composite sheet depend on the formulation of composite material. The presence of fly ash particles and fly ash/ expanded graphite in the polymer system allows the composite sheet to acquire good mechanical and electrostatic charge dissipative properties. Static voltage decay rate and decay value measurement were carried out for LDPE and LDPE/fly ash/expanded graphite composite sheet. LDPE/fly ash/expanded graphite composite sheet having high percentage of expanded graphite showed good electrostatic charge dissipative properties. Further, structural analysis, surface morphology, thermal stability and mechanical properties have been explored by XRD, SEM, TGA and tensile testing. Copyright © 2016 VBRI Press.

A COMPARATIVE INVESTIGATION ON PHYSICAL AND MECHANICAL PROPERTIES OF MMC REINFORCED WITH WASTE MATERIALS

Abstract— Aluminium alloy based metal matrix composites (MMC) are produced with agro waste Rice Husk Ash (RHA) and industrial waste Fly Ash as reinforcement. By the continuous stir casting method the MMCs were fabricated in a bottom pouring furnace at 7000C. A rectangular metal mould was used to prepare the casting having dimension 300x50x20 mm3. The effect of adding the different reinforcement were realized through various mechanical behaviour tests. Based upon the standards in the mechanical workshop samples were prepared for measuring mechanical properties such as Impact strength, Compression strength, Tensile strength, Brinell hardness and Density test of both the MMCs. The Fly Ash and Rice Husk distributions in the MMCs were confirmed through the examinations conducted of the microstructure on image analyzer and scanning electron micrographs. Results thus found revealed that there is a great effect of reinforcing Flyash and Rice Husk in aluminium alloy matrix composites. Fly ash gave more enhanced mechanical properties as compared to Rice Husk. Thus selection of waste material from industry based and agro based for reinforcement was found one of the most important criteria for fabricating aluminium matrix composites.

Processing of cenosphere/HDPE syntactic foams using an industrial scale polymer injection molding machine

Rapid production of high quality components is the key to cost reduction in industrial applications. The present work is the first attempt of manufacturing syntactic foams, hollow particle filled lightweight composites, using an industrial scale injection molding machine. High density polyethylene (HDPE) is used as the matrix material and fly ash cenospheres are used as the filler. Development of syntactic foams with cenospheres serves dual purpose of beneficial utilization of industrial waste fly ash and reduction in the cost of the component. The pressure and temperature used in the injection molding process are optimized to minimize fracture of cenospheres and obtain complete mixing of cenospheres with HDPE. The optimized parameters are used for manufacturing syntactic foams with 20, 40 and 60wt.% cenospheres. With increasing cenosphere content, density and strength reduce and modulus increases. Surface modification of constituents results in rise in strength with increasing filler content. A theoretical model based on a differential scheme is used to estimate the properties of cenospheres by conducting parametric studies because of inherent difficulties in direct measurement of cenosphere properties. The potential for using the optimized injection molding process is demonstrated by casting several industrial components.

Utilization of Industrial Waste Copper Slag and Fly Ash in Concrete

Utilization of Industrial Waste Copper Slag and Fly Ash in Concrete

Development and Characterizations of Green Coupling Agent Coated Fly Ash Reinforced Recycled Polypropylene Matrix Composites

Two industrial wastes fly ash and polypropylene was used to develop novel composite materials. The fly ash (FA) particles were coated with stearic acid (SA) and palmitic acid (PA) in 1 wt% concentration. The surface coated fly ash particles were incorporated as filler in recycled polypropylene (RPP) matrix composites by melt mixing in 1:1 weight ratio. The composites were tested for their flexural properties, impact behaviour, dynamic mechanical properties and fracture surface analysis. Increase in flexural strength, modulus and impact strength was observed in the coated FA/RPP composites. 1wt % PA coated FA/RPP composites showed great increase in flexural strength. In 1 wt% SA treated FA/RPP (RFASA1) composites highest shift in glass transition to a higher temperature were found. Fracture surface analysis revealed efficient filler matrix interactions in the SA and PA treated FA/RPP composites. Thus, green, renewable, inexpensive chemicals like stearic and palmitic acid was found to be an effective coupling agent in FA/RPP composites.

Study on the Strength Properties and Failure Mode of Recycled Sludge Lightweight Soil

Lightweight technology is to transform the discarded materials, such as dredged silt, construction waste soil, waste foam plastics, industrial waste fly ash, waste gypsum, etc., into lightweight soil. This kind of soil has been utilized comprehensively, which can produce good economic benefit, environmental and social benefits. In order to further investigate the properties of mixed lightweight soil, this paper uses indoor test method to study the recycled sludge lightweight soil samples prepared from the construction waste soil by mixing with EPS particles and cement according to certain mass/volume ratio and cured in standard curing conditions. The strength properties and failure mode are analyzed using the direct shear test and unconfined compressive strength test, and the effect of curing period, cement content, EPS particle fraction, etc., on the strength and failure mode is analyzed.

Attenuation of Metal Bioavailability in Acidic Multi-Metal Contaminated Soil Treated with Fly Ash and Steel Slag

A pot experiment was conducted with multi-metal (Pb, Cd, Cu, and Zn) contaminated acidic soil to investigate changes in available metal burden resulting from the application of industrial wastes (fly ash and steel slag). The efficiency of amendments-induced metal stabilization was evaluated by diffusive gradients in thin films (DGT), sequential extraction, and plant uptake. The stability of remediation was assessed by an acidification test and by chemical equilibrium modeling. Addition of fly ash (20 g kg−1) and steel slag (3 g kg−1) resulted in similar increase in soil pH. Both amendments significantly decreased the concentrations of metals measured with DGT (CDGT) and the metal uptake by Oryza sativa L. Significant correlations were found between CDGT and the concentration of a combination of metal fractions (exchangeable, bound to carbonates, and bound to Fe/Mn oxides), unraveling the labile species that participate in the flux of metal resupply. The capability of metal resupply, as reflected by the R (ratio of CDGT to pore water metal concentration) values, significantly decreased in the amended soils. The CDGT correlated well with the plant uptake, suggesting that DGT is a good indicator for bioavailability. Acidification raised the extractable metal concentration in amended soil but the concentration did not return to the pre-amendment level. Equilibrium modeling indicated that the soil amendments induced the precipitation of several Fe, Al and Ca minerals, which may play a positive role in metal stabilization. Chemical stabilization with alkaline amendments could be an effective and stable soil remediation strategy for attenuating metal bioavailability and reducing plant metal uptake.

Alkali activation of biomass fly ash–metakaolin blends

In this paper alkali activation of biomass fly ash – an industrial waste and biomass fly ash–metakaolin blends is investigated. Mixtures of biomass fly ash and commercially available metakaolin ARGICAL 1200 were used as solid components. Different molar volumes of NaOH and sodium silicate solutions were used for the preparation of alkali activators. The mechanical strength was determined after 10days of curing. The concentration of alkali solution and the mix compositions were optimised for the preparation of mortar samples. The mineral and microstructural properties of the alkali activated binders were carried out by X-ray diffraction (XRD), Thermogravimetric/Differential thermal analysis (TG/DTA) and Scanning electron microscopy (SEM) methods. The mortar samples of biomass fly ashes gave a compressive strength of 18MPa. The metakaolin incorporated samples showed a higher strength. The highest value was obtained for 40% metakaolin incorporated mortars for around 38MPa. The biomass fly ash metakaolin blend is working well in the alkali activation application resulting in the contribution of both aluminosilicates and hydrated phases formation.

Effect of reinforcements and heat treatment on tensile strength of Al-Si-Mg based hybrid composite

Metal Matrix Composites (MMCs) constitute an important class of design and weight-efficient structural materials that are encouraging every sphere of engineering applications and mainly in aerospace applications. The present investigation is focused on formation of a hybrid composite by using industrial waste fly ash and E glass short fibers by dispersing them into AA7075 alloy by Stir casting method. The MMC is obtained for the different compositions of E-glass and Fly ash particulates. The test specimens are prepared to the standard size by turning and facing operations to conduct tensile test and the specimens are subjected to heat treatment. The specimens were tested for tensile test at different loads by using Universal Test Machine. The results are plotted and it is concluded that the MMC obtained has got better tensile strength compared to Aluminum alloy (7075) alone. Further, tensile strength slightly increased with I hour aging heat treatment.

Study on Preparation and Properties of Cement-Based Foamed Lightweight Thermal Insulation Material

A cement-based foamed lightweight thermal insulation material was prepared with cement, industrial waste (fly ash, steel slag) as the main raw materials, by using self-developed composite activator and foaming agent. The influence of foam content on dry density, compressive strength and thermal conductivity coefficient of material was studied, the activation mechanism of composite activator to fly ash and steel slag was discussed. Results showed that, the dry density and compressive strength of material decreased, and thermal conductivity coefficient decreased first and then increased with the increasing foam content.

Fabrication and characterization of macroporous flyash ceramic pellets

Macroporous ceramic pellets (MCPs) were prepared from industrial waste flyash via a mechanical foaming and pseudo-double-emulsion (PDE) method. The MCPs with different relative densities (ρr) were characterized in terms of total and open porosities (εt and εo), average pore size (davg), specific surface area (Sp), surface roughness, and microstructure. The inner and outer pore structure of the MCPs was found to be composed of interconnected circular pores. The average size of the MCPs was controlled over the range of 2.0–3.0 mm by varying the solid loading ratio of slurries. Increasing the slurry loading led to increasing viscosity of the slurry and consequently greater size of the MCPs. The physical properties of the MCPs investigated herein (i.e., εt, εo, davg, Sp, and surface roughness) increased with decreasing ρr (i.e., increasing foaming ratio). It was found that the degree of pore connectivity can be controlled by the ρr of the MCPs. Heavy metal leaching test results showed that the amount of heavy metals released from the MCPs was much lower than that from flyash powders. The results were attributed to melting and subsequent immobilization of the heavy metals as well as their partial sublimation during the sintering process.

Experimental Study on Freeze-Thaw Resistance Durablilty of High Performance Concrete

Freeze-thaw cycle experiments on high performance concrete were carried out while cement was respectively replaced by fly ash for 30%～50%. The test results showed that maximum weight loss rate of concrete was 1.78% and minimum relative dynamic elastic modulus was 94.08% after 300 freeze-thaw cycles for high performance concrete based on low water-cement ratio, efficient air-water-reducing agent and large quantities of industrial waste fly ash. The test data were far less than limits of 5% and 60% in specification. Freeze-thaw resistance performance of high performance concrete with large volume fly ash was excellent according to test results. The high performance concrete with large volume fly ash can meet the requirements of frost resistance performance of concrete in the cold regions. Particularly, it can be fit for the railway concrete engineering.

Recycling of fly ash for preparing porous mullite membrane supports with titania addition

In order to effectively utilize industrial waste fly ash, porous mullite ceramic membrane supports were prepared from fly ash and calcined bauxite with chemically pure titania as sintering additive. The effects of TiO 2 on the sintering behaviors and main properties of porous mullite were studied in detail. Due to the addition of titania, the sintering of the flyash-based mullite was inhibited at low temperatures, but effectively improved at high temperatures, the latter is suitable for preparing porous mullite membrane supports by incomplete sintering. Titania entered into liquid glassy phase with low high-temperature viscosity during sintering, resulting in the improvement of sintering activity, as well as the lowering of secondary mullitization temperature (where 2.0% titania). Between 1300 and 1500 °C, with increasing titania content, the samples exhibit increased trends in both linear shrinkage percent and bulk density, but a slightly decreased trend in open porosity, at all sintering temperatures. At 1300–1500 °C, the samples sintered at 1450 °C for 2 h exhibit the lowest shrinkage and bulk density, as well as the highest open porosities in the investigated titania content range of 0–6.0 wt.%. Also, with increasing titania content, the pore size decreases slightly but the three-point flexural strength increases gradually at 1450 °C.

Utilisation of Industrial Waste Flyash as an Adulterant to Clay for The Manufacture of Mangalore Roofing Tiles

Utilisation of Industrial Waste Flyash as an Adulterant to Clay for The Manufacture of Mangalore Roofing Tiles