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Sorption characteristics and mechanisms of ammonium by coal by-products: slag, honeycomb-cinder and coal gangue
Zhang, L. Y.; Zhang, H. Y.; Guo, W. & Tian, Y. L.
Abstract
The adsorption behaviors of ammonium from
aqueous solutions were investigated for three solid coal
wastes, slag, honeycomb-cinder and coal gangue. The
ammonium sorption processes were well modeled by the
pseudo second-order model (R2 > 0.99). The experimental
data were fitted to both the Langmuir model and the Freundlich model, with the Langmuir model better representing the data. The maximum ammonium sorption
capacities calculated from the Langmuir model were 3.1,
5.0 and 6.0 mg/g for the slag, honeycomb-cinder and coal
gangue samples, respectively. The pH value of the solution
affected the ammonium removal, and the higher uptakes
found in either neutral or alkaline conditions for the three
materials. The thermodynamic parameters, ΔH, were calculated to be 29.75, 25.21 and 17.91 kJ/mol for the SL, HC
and CG samples, respectively, with the positive values
indicating that the ammonium sorption processes were
endothermic. Based on the results, it can be concluded that
coal gangue may have more potential for being used as a
sorbent for the ammonium removal from wastewater
among the three coal by-products.
Keywords
Ammonium; Coal gangue; Honeycomb-cinder; Slag; Sorption
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