Influence of coal fly ash particle size on structure and adsorption properties of forming adsorbents for Cr⁶⁺

Abstract

Forming adsorbents FFA-R, FFA-A and FFA-B were prepared from different particle size coal fly ashes FA-R, FA-A and FA-B, their average particle sizes (d ₅₀) were 15.75, 3.61 and 1.73 μm respectively. The structure and adsorption properties for Cr⁶⁺ of forming adsorbents from aqueous solution were studied. The results show that forming adsorbent prepared from the coal fly ash with smaller particle size exhibits higher specific surface area, higher pore volume and better adsorption properties for Cr⁶⁺.The adsorption kinetics of Cr⁶⁺ on FFA-R, FFA-A and FFA-B fitts the second order kinetic model and the second adsorption rate constants are 7.523, 3.197 and 2.187 mg·g^-1· min^-1/2, respectively. The adsorption of Cr⁶⁺ on FFA-R, FFA-A and FFA-B can be described in terms of Langmuir isotherms better, and the adsorption processes are spontaneous and exothermic.

Keywords

coal fly ash / forming adsorbent / adsorption / Cr⁶⁺

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