title: Adsorption of aromatic compounds on porous covalent triazine-based framework.
abstract: Covalent triazine-based frameworks (CTFs) are an emerging class of polymers whose adsorption properties of organic chemicals are not well understood. The main objective of this work was to evaluate combined effects of the functional groups of aromatic solutes and the triazine structure of a synthesized CTF on adsorption in aqueous solutions. Adsorption of the hydroxyl-, amino-, nitro-, and sulfonate-substituted monocyclic and bicyclic aromatic compounds was generally stronger than their non-substituted, nonpolar counterparts (benzene and naphthalene). When compared with Amberlite XAD-4 resin, one of the most common and widely used polymeric adsorbents, the CTF showed much stronger adsorption toward the polar and/or ionic compounds. To explain the adsorption enhancement of CTF, several specific, non-hydrophobic mechanisms were proposed, including hydrogen bonding (hydroxyl- and amino-substituted compounds), electrostatic attraction (anionized compounds), and π-π electron-donor-acceptor (EDA) interaction (nitroaromatic compounds) with the triazine structure of CTF. The hypothesized mechanisms were further supported by the observed pH dependence of adsorption. Resulting from size exclusion, adsorption of large-size dissolved humic acids on the homogeneous, nanopored (1.2 nm in size) CTF was negligible and did not affect adsorption of aromatic solutes. Additional advantages of fast adsorption/desorption kinetics and complete adsorption reversibility made CTF a superior adsorbent for aromatic compounds.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, PR China.
authors.forename: Jingliang
authors.initials: J
authors.lastname: Liu
authors.forename: Enmin
authors.initials: E
authors.lastname: Zong
authors.forename: Heyun
authors.initials: H
authors.lastname: Fu
authors.forename: Shourong
authors.initials: S
authors.lastname: Zheng
authors.forename: Zhaoyi
authors.initials: Z
authors.lastname: Xu
authors.forename: Dongqiang
authors.initials: D
authors.lastname: Zhu