Publikacje

Abstract:

The aim of the study was to assess the possibility of using natural carbonaceous materials such as
peat, lignite, and hard coal as low-cost sorbents for the removal of Direct Orange 26 azo dye from an aqueous
solution. The adsorption kinetics and the influence of experimental conditions were investigated. The following
materials were used in the research: azo dye Direct Orange 26, Spill-Sorb “Fison” peat (Alberta, Canada), lignite
(Bełchatów, Poland), and hard coal (“Zofiówka” mine, Poland). The morphology and porous structure of the
absorbents were tested. Dye sorption was carried out under static conditions, with different doses of sorbents,
pH of the solution, and ionic strength. It was observed that the adsorption of Direct Orange 26 dye on all three
adsorbents was strongly dependent on the pH of the solution, while the ionic strength of the solution did not affect
the adsorption efficiency. The adsorption kinetics were consistent with the pseudo-second-order reaction model.
The stage which determines the rate of adsorption is the diffusion of the dye in the near-surface layer. The process
of equilibrium adsorption of Direct Orange 26 dye on all tested adsorbents is best described by the Langmuir
isotherm. The maximum adsorption capacity for peat, brown coal and hard coal was 17.7, 15.1 and 13.8 mg/g,
respectively. The results indicate that peat, lignite, and hard coal can be considered as alternative adsorbents for
removing azo dyes from aqueous solutions.

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Removal of Direct Orange 26 azo dye from water using natural carbonaceous materials