Nanopore-filling effect of phenanthrene sorption on modified black carbon

Abstract

Black carbon was produced by slow pyrolysis under an oxygen-limited condition at 500 °C, and was modified by some chemical methods (oxidation, hydrolysis, activation, and surface recombination). The modified samples were characterized by using elemental analysis, Fourier transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) surface analysis, Boehm titration, cation exchange capacity(CEC)analysis, CO2 adsorption analysis, and then used to investigate the sorption behavior of phenanthrene. The results showed that the activation of ZnCl2 gave a maximum nanopore volume of 96.5 μL/g and a specific surface area of 241 m2/g, while the oxidation of NaClO gave a minimum nanopore volume of 63.3 μL/g and a specific surface area of 158 m2/g. The FTIR, XPS, and Boehm titration analysis showed that the new oxygen-containing functional groups were introduced during the oxidation treatments of H2O2 and NaClO. The sorption of phenanthrene on all samples was typically nonlinear, and the nonlinear factor (n) was negatively correlated with Vo, especially with Vo at 0–1.1 nm. The sorption parameter (log KOC) was positively correlated with nanopore volume (Vo) and specific surface area (SSA). Moreover, the model analysis showed that the nanopore filling was the main sorption mechanism, and molecular sieve effect was observed in the sorption of phenanthrene.