Thermally treated sediments with high organic carbon content were proven to be more efficient in retaining carbon in comparison to common biochars. These particles also showed high sorption to various pollutants. The sorption of five organic contaminants and three heavy metals was investigated and compared to evaluate the potential use of thermally treated sediments (TTSs) with high organic matter content. Phenanthrene (PHE) and sulfamethoxazole (SMX) showed increased sorption with increased pyrolysis temperature, while the sorption of bisphenol A (BPA), ofloxacin (OFL) and norfloxacin (NOR) in the original sediment was comparable to those in the thermally treated samples. Electrostatic repulsion played an important role in SMX sorption as suggested by its lowest hydrophobicity-normalized sorption coefficients among the five chemicals. Cu (II) and Cd (II) sorption generally decreased with the increasing of pyrolysis temperature, concurred with decreased oxygen-containing functional groups of the adsorbents. Sediment particles pyrolyzed at 400 and 500� C showed higher sorption to Pb (II) than other temperatures. The small hydrated ionic radius of Pb (II) may enable its close contact with solid particles and thus facilitated the diffusion of Pb (II) into the pores and the formation of cation�p bond with aromatic structures generated by pyrolysis. Consider the specificity of SMX sorption, desorption properties and sorption thermodynamic was used to comprehensive understanding of SMX�TTS interactions. Desorption ratio of the adsorbed SMX in TTSs generally decreased with increased pyrolytic temperature and with decreased solid-phase concentrations. The thermodynamic analysis showed that the higher entropy increase was well related with the decreased desorption ratio with increased solid-phase concentration for the original sediments. Most sorption of organic contaminants and heavy metals on TTSs showed higher sorption than natural adsorbents and most of the biochars from biomass, indicating that sediment with high organic carbon content could be used as a source of biochar production to benefit organic contaminants and heavy metals immobilization.

Comparison of adsorption behavior of organic contaminants and heavy metals on thermally treated sediments with high organic carbon content

248th National Meeting (2014)

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