Enhanced adsorption of phthalic acid esters (PAEs) from aqueous solution by alkylbenzene-functionalized polypropylene nonwoven and its adsorption mechanism insight

In this study, a novel adsorbent (PP-g-GMA-(n-OA)) was designed and synthesized via grafting polymerization of glycidyl methacrylate (GMA), and subsequent amination modification of 4-n-Octylaniline (n-OA) on the surface of polypropylene nonwoven. The morphological structure, composition and wettability of the PP-g-GMA-(n-OA) were thoroughly characterized by SEM, FT-IR, XPS, water contact angle. Results elucidated that the hydrophilic hydroxyl/amino groups and hydrophobic aromatic rings were successfully introduced onto the surface of PP-g-GMA-(n-OA), which could be selectively bind similar functional groups of phthalic acid esters (PAEs) by different adsorption interactions to achieve more satisfactory adsorption efficiently. Compared to unmodified PP nonwoven and several other reported adsorbents, PP-g-GMA-(n-OA) exhibited relatively high adsorption capacity for dioctyl phthalate (DOP) and dibutyl phthalate (DBP) (272.4 mg/g and 184.9 mg/g, respectively). The Freundlich isotherm model can be satisfactorily fitted the isotherm data, elucidating that it was a multilayer heterogeneous adsorption. The thermodynamic parameters confirmed the adsorption was spontaneous and exothermic process. In additional, the adsorbent still exhibited excellent adsorption capacity after multiple desorption/adsorption cycles. Adsorption mechanism was also investigated using the results of adsorption behavior and spectrum analyses after adsorption, which demonstrated that synergistic effect of π-π interaction, hydrophobic interaction and hydrogen bonds, especially π-π interaction played a dominated role in DOP and DBP adsorption. The current study provided a strategy for design and fabrication of high effective and low-cost adsorbents for remove of target contaminants from wastewater.