Phenanthrene and Pyrene Sorption and Intraparticle Diffusion in Polyoxymethylene, Coke, and Activated Carbon

Abstract

We report sorption isotherms and uptake kinetics for phenanthrene and pyrene with three organic model sorbents: polyoxymethylene (POM), coke, and activated carbon. We combine batch equilibration and kinetic experiments with the direct observation of the long-term diffusion of phenanthrene and pyrene as measured within cross-sectioned particles using microprobe laser-desorption laser-ionization mass spectroscopy (muL2MS). For POM pellets, the intraparticle concentration profiles predicted from kinetic batch experiments and a polymer diffusion model with spherical geometry are in agreement with the independent muL2MS measurements. For coke particles, the apparent diffusivities decreased with smaller particle size. These trends in diffusivities were described by a sorption-retarded pore diffusion model with a particle-size-dependent solid-water partitioning coefficient obtained from apparent equilibrium observed in the kinetic batch studies. For activated carbon, the muL2MS measurements showed faster radial diffusion of phenanthrene and pyrene into the particle interior than predicted from diffusion models based on a single sorption domain and diffusivity. A branched pore kinetic model, comprising polycyclic aromatic hydrocarbon (PAH) macropore diffusion with kinetic exchange of PAH between macroporous and microporous domains, fits the experimental observations better. Because of parallel macro- and microdiffusion processes, nonlinear sorption isotherms, and a concentration-dependent diffusivity, it is not possible to make independent parameter estimations for intraparticle diffusion in activated carbon using our present procedures.

Investigation of heavy metal (Cu, Pb, Cd, and Cr) stabilization in river sediment by nano-zero-valent iron/activated carbon composite

“…Lebo et al (2003) compared the coarse and fine version of two carbons for reducing bioavailability of hydrophobic organic carbon and concluded that fine particles in the range of 0.075-0.3 mm are better. Ahn et al (2005) argued that fine particles were more effective because of the larger external surface area and short intra-and interparticle diffusion path. Leaching of Cu, Pb, and Cr increased slightly as even finer particles (0.025-0.075 mm) were used.…”

Sorption kinetics of polycyclic aromatic hydrocarbons removal using granular activated carbon: Intraparticle diffusion coefficients

“…As a general rule, values of D s were in the same order as the measured values of the PAH evaluated. Ahn et al [43] reported surface diffusion coefficients for phenanthrene and pyrene on coarse activated carbon using a branched pore kinetic model, the values of which were 2 × 10 −15 and 3 × 10 −16 m 2 s −1 , respectively.…”

Impact of petroleum coke characteristics on the adsorption of the organic fractions from oil sands process-affected water

“…BET surface area of PC was calculated as 7.7 m 2 /g ( Table 4). The low surface area of PC as compared to 912 and 800 m 2 /g for GAC and PAC, respectively, implies that PC has lower porosity as compared to the highly porous structure of the GAC and PAC (Ahn et al 2005;Alhamed and Bamufleh 2009;Carter et al 2011;Ding et al 2008;Lu and Sorial 2004). The pore size distribution curves of PC, GAC, and PAC are shown in Fig.…”