Bio‐based macroporous polymer sorbents: Synthesis, physicochemical properties and sorption kinetics

Abstract

Macroporous polymeric sorbents were synthesized via high internal phase emulsion (HIPE) templating. For this aim, water‐in‐oil (w/o) HIPEs were prepared with 80 vol.% of aqueous internal phase whereas plant‐based β‐myrcene (My) and D‐limonene (Lim) were used as renewable building blocks in the continuous oil phase. Moreover, biocompatible ethylene glycol dimetacrylate (EGDMA) was also added as a crosslinker comonomer. By varying the total volume fraction of My and Lim in the continuous phase composition between 90% and 50%, 14 different HIPE formulations were prepared. After polymerization of HIPE templates 28 different sorbents were obtained depending on the purification procedure (extraction & drying under vacuum or freeze drying). The effect of terpene composition in the obtained sorbents was investigated in terms of cross‐link density (υ), the molecular weight (Mc) and pore morphology. In this context, chemical structures and pore morphologies were characterized by FTIR spectroscopy and SEM analysis, respectively. The Brunauer‐Emmet‐Teller (BET) specific surface area was also measured to determine the relationship between pore morphology and surface area. Based on the characterization results, two sorbents were selected as model for sorption tests. Thereafter, solvent sorption tests were performed by immersing sorbents in either hexane, dichloromethane, deionized water, seawater, solvent/water mixture, or solvent/seawater mixture to determine maximum sorption capacities and determine reusability of the sorbents. Moreover, experimental data was fitted to pseudo‐first order and pseudo second order kinetic models, as well as Freundlich and Langmuir isotherms. In the end, it was found that varying My and Lim ratio is the key parameter of controlling pore morphology and physicochemical properties. Moreover, it was shown that resulting sorbents can be efficiently used in oil/water separation processes repeatedly for several cycles.