Summary: Naphthalene and o-Xylene Adsorption
onto High Carbon Fly Ash
M. Melih Demirkan1
; Ahmet H. Aydilek, M.ASCE2
; Eric A. Seagren, A.M.ASCE3
; and James C. Hower4
Abstract: Adsorption is an effective remediation technique for petroleum hydrocarbons because of its ease of use and high efficiency. The
utilization of high-carbon content industrial by-products in such applications can present significant economic and environmental advantages.
In this study, batch adsorption tests and petrographic analyses were used to investigate the adsorption of two nonpolar petroleum contam-
inants, naphthalene and o-xylene, onto seven fly ashes with varying carbon contents, with powdered activated carbon (PAC) as a control. Six
equilibrium isotherm models were used to evaluate the batch data. The results yielded nonlinear sorption isotherms characterized by high
sorption capacity at low concentrations. The naphthalene and o-xylene adsorption capacity of the fly ashes was correlated with the unburned
carbon content, specific surface area of the sorbent, and the percentage of the anisotropic and isotropic carbon content of the ash. On the basis
of the Polanyi-Dubinin-Manes model, a pore-filling mechanism is the dominant mechanism for the adsorption of the nonpolar organic
chemicals onto PAC, whereas the adsorption onto fly ash is likely to be governed by the unburned carbon content and the specific surface
area of the ash. DOI: 10.1061/(ASCE)EE.1943-7870.0000335. © 2011 American Society of Civil Engineers.
CE Database subject headings: Adsorption; Hydrocarbons; Fly ash; Activated carbon.
Author keywords: Adsorption; Hydrocarbons; Fly ash; Activated Carbon.
Groundwater contamination by petroleum hydrocarbons is a com-