Adsorption of Polycyclic Aromatic Hydrocarbons onto Activated Carbon from Non‐Aqueous Media: 1. The Influence of the Organic Solvent Polarity (original) (raw)
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Asian Journal of Chemistry, 2013
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Activated carbon adsorption of PAHs from vegetable oil used in soil remediation
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Granular activated carbon (GAC) was evaluated as a suitable sorbent for polycyclic aromatic hydrocarbons (PAHs) removal from aqueous solutions. For this purpose, kinetic measurements on the extraction of a family of six PAHs were taken. A morphology study was performed by means of a scanning electron microscopy (SEM) analysis of GAC samples. Analyses of the batch rate data for each PAH were carried out using two kinetic models: the homogenous particle diffusion model (HPDM) and the shell progressive model (SPM). The process was controlled by diffusion rate the solutes (PAHs) that penetrated the reacted layer at PAH concentrations in the range of 0.2-10 mg L −1 . The effective particle diffusion coefficients (D eff ) derived from the two models were determined from the batch rate data. The Weber and Morris intraparticle diffusion model made a double contribution to the surface and pore diffusivities in the sorption process. The D eff values derived from both the HPMD and SPM equations varied from 1.1 × 10 −13 to 6.0 × 10 −14 m 2 s −1 .
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The aim of this paper is to study the abatement of three-ring polycyclic aromatic hydrocarbons (PAHs) from hot gas emissions during energy generation in coal combustion. The three-ring PAHs are one of the most abundant PAH groups emitted during coal combustion. Four of them—Acenaphthene (Ac), Phenanthrene (Phe), Fluorene (Fu) and Anthracene (An)—have been listed by US EPA as priority pollutants. The three-ring PAH adsorption capacities are related to the textural properties of the 16 sorbents used in this work. Single and multiple linear regressions —principal component regression (PCR)—were applied in this study. The main conclusions reached are two: (1) the micropore volume is the most determinant parameter for these PAH removal; (2) the adsorption of three-ring PAH by sorbents from waste hot gas emissions is inversely proportional to their volatility: the lower the PAH volatility, the higher the adsorbent adsorption capacity. The adsorption isotherms show that Phe and An, both examples of PAHs with three aromatic rings, behave similarly. However, their behaviour differs from that of Ac and Fu, compounds where only two of their three rings exhibit an aromatic nature.
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Addition of activated carbon (AC) to sediments has been proposed as a method to reduce ecotoxicological risks of sedimentbound contaminants. The present study explores the effectiveness of granular AC (GAC) in extracting polycyclic aromatic hydrocarbon (PAH) from highly contaminated sediments. Four candidate GAC materials were screened in terms of PAH extraction efficiency using single-step 24-h GAC extractions, with traditional 24-h Tenax extraction as a reference. Subsequently, sorption of native PAHs to the best performing GAC 1240W (0.45-1.70 mm) was studied for sediment only and for GAC-sediment mixtures at different GAC-sediment weight ratios, using 76-mm polyoxymethylene (POM) passive samplers. Granular AC sorption parameters for PAHs were determined by subtracting the contribution of PAH sorption to sediment from PAH sorption to the GAC-sediment mixture. It appears that the binding of PAHs and the effectiveness of GAC to reduce sediment porewater concentrations were highly dependent on the GAC-sediment mixing ratio and hydrophobicity of the PAH. Despite the considerable fouling of GAC by organic matter and oil, 50 to 90% of the most available PAH was extracted by the GAC during a 28-d contact time, at a dose as low as 4%, which also is a feasible dose in field-scale applications aimed at cleaning the sediment by GAC addition and removal. Environ. Toxicol. Chem.
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