Impact of organic matter properties on sorption domains of phenanthrene on chemically modified geosorbents and synthesized charcoals

Abstract

To study the impact of organic matter (OM) properties on different sorption domain of hydrophobic organic contaminants, phenanthrene sorption on chemically modified geosorbents and synthesized charcoals (SCs) was investigated and explored using Dual-Mode model (DMM). Sorption of phenanthrene on two geosorbents, peat and lignite, and their modified forms by hydrolysis, oxidation, and oximation, as well as on three SCs with different pyrolytic degrees changed were significantly affected by the aromaticity (A) and polarity index (PI) of OM. Positive correlation between OM normalized parameter of Langmuir sorption capacity of DMM (S(DM)/f(OM)) and A×PI(-1) was observed. To distinguish the deviation of DMM, S(DM) was corrected by assigning the Langmuir affinity parameter (b(DM)) of DMM to the high energy Langmuir affinity parameter (b(H)) in Dual-Langmuir model (DLM). More significant correlation was observed between A×PI(-1) and corrected S(DM), which confirms that the nonpolarity and aromaticity of sorbent OM contribute much to the hydrophobic organic contaminants sorption with high energy. Besides, the partition coefficient of linear domain of DMM normalized by OM (K(P)/f(OM)) was positively related to PI(-1) rather than negatively related to PI, suggesting that PI(-1) is more suitable than -PI to evaluate the nonpolarity of sorbent OM.