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Number of results: 4
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Abstract

The study investigates chemical modifications of coal fly ash (FA) treated with HCl or NH4HCO3 or NaOH or Na2edta, based on the research conducted to examine the behaviour of Cd(II) and Pb(II) ions adsorbed from water solution on treated fly ash. In laboratory tests, the equilibrium and kinetics were examined applying various temperatures (293 - 333 K) and pH (2 - 11) values. The maximum Cd(II) and Pb(II) ions adsorption capacity obtained at 293 K, pH 9 and mixing time 2 h from the Langmuir model can be grouped in the following order: FA-NaOH > FA-NH4HCO3 > FA > FA-Na2edta > FA-HCl. The morphology of fly ash grains was examined via small-angle X-ray scattering (SAXS) and images of scanning electron microscope (SEM). The adsorption kinetics data were well fitted by a pseudo-second-order rate model but showed a very poor fit for the pseudofirst order model. The intra-particle model also revealed that there are two separate stages in the sorption process, i.e. the external diffusion and the inter-particle diffusion. Thermodynamics parameters such as free energy, enthalpy and entropy were also determined. A laboratory test demonstrated that the modified coal fly ash worked well for the Cd(II) and Pb(II) ion uptake from polluted waters.

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Authors and Affiliations

Eleonora Sočo
Jan Kalembkiewicz
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Abstract

In the present paper changes of polycyclic aromatic hydrocarbons (PAHs) content were evaluated during composting of sewage sludge stabilized with coal fly ash. The content of PAHs in sewage sludge used for composting was I 0385 μg/kg (±830). In fly ash only three PAHs were determined (phenanthrene - 0.9 μg/kg, anthraccnc - 1.9 μg/kg and chrysenc - 2.7 μg/kg). Addition of fly ash to composted sewagesludge had various - dependent on its share - effect on PAHs mineralization. Relatively best degradation (66.3%) was noted when sewage sludge was mixed with fly ash in amount 20% (w/w). In composted sewage sludge and sludge with 30% addition of fly ash a decrease of PAH content was also observed (38 and 32.4% respectively). Relatively "best" mineralization was noted for 3-ring PAHs. Estimated half-lives of all investigated compounds depended on individual PAHs properties and ranged from 59 to 1164 days.
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Authors and Affiliations

Patryk Oleszczuk
Stanisław Baran
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Abstract

A laboratory study was performed to study the effects of various operating factors, viz. adsorbent dose, contact time, solution pH, stirring speed, initial concentration and temperature on the adsorption of triphenyltin chloride (TPT) onto coal fly ash supported nZnO (CFAZ). The adsorption capacity increases with increase in the adsorbent amount, contact time, pH, stirring speed and initial TPT concentration, and decrease with increase in the solution temperature. The adsorption data have been analyzed by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) adsorption models to determine the mechanistic parameters associated with the adsorption process while the kinetic data were analyzed by pseudo first-order, pseudo second-order, Elovich, fractional power and intraparticle diffusivity kinetic models. The thermodynamic parameters of the process were also determined. The results of this study show that 0.5 g of CFAZ was able to remove up to 99.60% of TPT from contaminated natural seawater at 60 min contact time, stirring speed of 200 rpm and at a pH of 8. It was also found that the equilibrium and kinetic data fitted better to Freundlich and pseudo second-order models, respectively. It can therefore be concluded that CFAZ can be effectively used for shipyard process wastewater treatment

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Authors and Affiliations

Olushola S. Ayanda
Olalekan S. Fatoki
Folahan A. Adekola
Bhekumusa J. Ximba
Olatunbosun S. Akinsoji
Leslie F. Petrik
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Abstract

The methods arc described for determinations of Al, Fe, Ca, Mg, Ba, Cr, Mn, Ni, Cu, Zn, Pb, Cd, V and Sr in botanical, coal fly ash and soil samples by flame atomic absorption spectrometry (FAAS), and inductively coupled plasma atomic emission spectrometry (!CP-AES). Special attention has been paid to sample preparation, an important stage at which a sample is explored to contaminants. Results of the analysis of all samples arc discussed.
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Authors and Affiliations

Krystyna Srogi

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