title: The power of power: electrokinetic control of PAH interactions with exfoliated graphite.
abstract: Exfoliated graphite (EG) exhibits exceptional sorption capacity for petroleum and dissolved hydrocarbons owing to its highly hydrophobic surface and wide pore size distribution. The high price of preparing EG, however, restricts its application. Methods which increase the rate or extent of sorption to EG even further are thus longed for. Here, we assess the effects of weak direct current (DC) fields on the sorption of the polycyclic aromatic hydrocarbon phenanthrene (PHE) to EG. DC applied to an ionic solution in a solid matrix invokes electroosmotic flow (EOF), i.e., the surface charge-induced movement of the solution. EG was exposed to weak DC fields in the presence of dissolved PHE to test if EOF increases transport of PHE to poorly accessible sorption sites. DC fields increased PHE sorption rates in EG sevenfold and reduced the desorption rate of sorbed PHE by >99%. EOF thus appeared to be highly effective in translocating PHE into pores, which contribute most of the sorption sites, but are difficult to access in the absence of EOF by molecular diffusion only. The observed 'power of power' may be used to kinetically regulate the interaction of sorbates with EG or other porous sorbents in environmental (bio-) technology.
authors: Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Microbiology, 04318 Leipzig, Germany.
authors: Jinyi
authors: J
authors: Qin
authors: University of Alberta, Department of Civil and Environmental Engineering, 3-133 Markin/CNRL Natural Resources Engineering Facility, Edmonton, AB T6G 2W2, Canada.
authors: Ahmed
authors: A
authors: Moustafa
authors: Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Microbiology, 04318 Leipzig, Germany.
authors: Hauke
authors: H
authors: Harms
authors: University of Alberta, Department of Civil and Environmental Engineering, 3-133 Markin/CNRL Natural Resources Engineering Facility, Edmonton, AB T6G 2W2, Canada.
authors: Mohamed Gamal
authors: MG
authors: El-Din
authors: Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Microbiology, 04318 Leipzig, Germany; University of Alberta, Department of Civil and Environmental Engineering, 3-133 Markin/CNRL Natural Resources Engineering Facility, Edmonton, AB T6G 2W2, Canada. Electronic address: lukas.wick@ufz.de.
authors: Lukas Y
authors: LY
authors: Wick
mesh_terms: D000327:Adsorption; D004563:Electrochemistry; D004574:Electromagnetic Fields; D053841:Electroosmosis; D006108:Graphite / Q000737:chemistry*; D010616:Phenanthrenes / Q000737:chemistry; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*; D013816:Thermodynamics; D013818:Thermogravimetry
chemical_list: D010616:Phenanthrenes; D011084:Polycyclic Aromatic Hydrocarbons; D006108:Graphite
keywords: DC electric field; Electroosmosis; Exfoliated graphite; Polycyclic aromatic hydrocarbons (PAH); Sorption