Roles of hydrophobic and hydrophilic fractions of dissolved organic matter in sorption of ketoprofen to biochars
Hydrophobic acid (HoA) and hydrophilic neutral (HiN) are two major fractions of dissolved organic matter (DOM). Their role in the sorption of ketoprofen (KTP) to wheat straw-derived biochars pyrolyzed at 300 °C (WS300) and 700 °C (WS700) was investigated to further probe the mechanisms responsible. WS700 has much higher pore volume and specific surface area (SSA) than WS300. Loading of HoA and HiN resulted in surface coverage of biochars. HoA with larger molecular size led to more pore blockage of biochars than HiN. Higher HoA binding affinity also caused a stronger competition with KTP on biochars. These factors reduced the accessibility of sorption sites for KTP, and significantly inhibited KTP sorption to biochar of lower SSA (i.e., WS300) by HoA. Water solubility (Sw) of KTP was slightly enhanced (3%) in the presence of HoA. In contrast, the presence of HiN reduced (22%) Sw of KTP. The decreased Sw of KTP by HiN exerted a more dominant influence than its competitive and loading effects, thus led to apparent enhanced sorption of KTP, especially to biochar of higher SSA (i.e., WS700). The results demonstrated the diverse effects of HoA and HiN on KTP sorption, which is helpful in understanding pharmaceutical-DOM-biochar interactions and environmental behaviors of pharmaceuticals.
KeywordsKetoprofen Biochar Sorption Solubility Dissolved organic matter (DOM) DOM fractions
Wheat straw-derived biochar at 300 °C
Wheat straw-derived biochar at 700 °C
Dissolved organic matter
Dissolved organic carbon
High performance liquid chromatography
Specific surface area
Scanning electron microscope
This study was supported by the National Natural Science Foundation of China (No. 41472231), Beijing Natural Science Foundation (No. 8162021), and the Fundamental Research Funds for the Central Universities (No. 2652017181).
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