The adsorption of phenanthrene onto activated carbons produced from Vitis vinifera leaf litter (a waste plant biomass) was investigated in this study. Zinc chloride (ZnCl 2) and phosphoric acid (H 3 PO 4) were utilised as activating agents in producing the activated carbons. The characterisation of the activated carbons was achieved with Fourier transform infrared spectroscopy (for surface functional groups), scanning electron microscopy (for surface morphology) and Brunauer-Emmett-Teller (BET) (for surface area determination). The adsorption of phenanthrene onto the activated carbons was optimised in terms of solution pH, adsorbent dosage, initial concentration of adsorbate solution and contact time. Experimental results showed that H 3 PO 4 modified activated carbon gave better yield (up to 58.40%) relative to ZnCl 2 modified activated carbon (only up to 47.08%). Meanwhile, surface characterisation showed that ZnCl 2 modification resulted in higher BET surface area (up to 616.60 m 2 /g) and total pore volume (up to 0.289 cm 3 /g) relative to BET surface area of up to 295.49 m 2 /g and total pore volume of up to 0.185 cm 3 /g obtained from H 3 PO 4 modified activated carbons. Adsorption equilibrium data fitted well into Freundlich isotherm model relative to other applied isotherm models, with maximum K f value of 1.27 for ZnCl 2 modified activated carbon and 1.16 K f value for H 3 PO 4 modified activated carbon. The maximum adsorption capacity for ZnCl 2 and H 3 PO 4 activated carbons for the removal of phenanthrene were 94.12 and 89.13 mg/g, respectively. Kinetic studies revealed that dynamic equilibrium was reached at 80 min contact time. Experimental data fitted best into the Elovich kinetic model relative to other kinetic models, based on the correlation coefficient (R 2) values obtained from kinetic studies. Chemisorption was deduced as a major phenanthrene removal pathway from aqueous solution and the physicochemical characteristics of the adsorbents have major influence on phenanthrene removal efficiencies.

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This study investigated the levels of polycyclic aromatic hydrocarbons (PAHs) in water and sediment samples of the Diep River freshwater system of Western Cape Province, South Africa. A solid-phase extraction -gas chromatography -flame ionisation detection (SPE-GC-FID) method was utilised to simultaneously determine the 16 United States Environmental Protection Agency (US EPA) listed priority PAHs in water and sediment samples. The seasonal averages of individual PAH detected at the studied sites, ranged between not detected (Nd) and 72.38 AE 9.58 μg/L in water samples and between Nd and 16.65 AE 2.63 μg/g in the corresponding sediment samples. The levels of PAHs measured in water and sediment samples were subjected to probabilistic risk assessment to predict the possibility of regulatory values being exceeded. The average percentage exceedence of 63.26 was obtained for PAHs in water samples of the Diep River, while the corresponding average percentage exceedence obtained for sediment sample was 63.71. Sufficient exposure of humans and aquatic organisms to the exceedance levels obtained, would cause adverse health effect.

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