Sorption of naphthalene and 2-naphthol onto porous carbonaceous materials as a function of pore size, metals, and oxygen-containing groups
2020
Wang, Bingyu | Wang, Yunhao | Wang, Jing
The important role of oxygen-containing groups of porous carbonaceous materials (PCMs) on sorption of organic compounds has been realized, but whether these groups can generate different joint effects, especially when oxidized PCMs with different pore sizes are complexed with heavy metals (Cu²⁺), remains ambiguous. The present study aimed to determine how pore sizes, metal ions, and oxygen-containing groups as a function affect the sorption of naphthalene and 2-naphthol to PCMs (e.g., activated carbons/ACs and mesoporous carbon/CMK-3). The H₂-reduced oxidized PCMs were used as the control of low oxygen content to avoid changes in the pore structure properties compared with the oxidized PCMs. Oxygen-containing groups considerably decreased the sorption of naphthalene and 2-naphthol to PCMs because of their weaker hydrophobic interaction and fewer sorption sites. Notably, naphthalene sorption on oxidized AC was inhibited with Cu²⁺ because of the steric constraint of Cu²⁺ hydration shells of the micropores. However, pore blockage by Cu²⁺ reduced the mesopore size of oxidized CMK-3, leading to enhanced pore filling effect and cation–π bonding, and therefore increased naphthalene sorption. For 2-naphthol, the sorption to oxidized PCMs initially increased and then decreased with increasing Cu²⁺ concentration attributed to the fewer Cu²⁺ acting as a bridging agent and excess Cu²⁺ competing for sorption sites.
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