Phenol adsorption and desorption with physically and chemically tailored porous polymers: Mechanistic variability associated with hyper-cross-linking and amination
Atkinson, Mohsen Ghafari, Yanbin Cui, Abdulrhman Alali, John D. . 2018
Understanding phenol adsorption-desorption mechanisms allows adsorbent tailoring to improve capacity and adsorbent reuse. AmberliteTM XAD4, a commercial styrenic polymer that is convenient to physically and che- mically modify, was functionalized with dimethylamine (DMA) or trimethylamine (TMA) and/or hyper-cross- linked with 1,2-dichloroethane. These modifications were applied to enhance individual and/or synergistic phenol adsorption mechanisms, including hydrogen bonding, electrostatic interactions, and π-π dispersion forces. While XAD4-DMA adsorbs more phenol at pH = 6, XAD4-TMA has 23% higher capacity at pH = 11 due to adsorbate deprotonation that increases electrostatic interactions. Combining hyper-cross-linking with ami- nation maximizes adsorption capacity due to synergistic impacts associated with increased micropore volume and surface affinity. Amine groups reduce desorption efficiency by 6–94% due to stronger adsorbate-adsorbent interactions compared to π-π dispersion forces. Isobutanol, which forms hydrogen bonds, is the most efficient desorption solvent, followed by chloroform, which has the same polarity index but does not hydrogen bond. n- Hexane only desorbs phenol removed with π-π dispersion forces and is not appropriate to regenerate aminated polymers. 0.1 N NaOH is an environmentally benign solvent for regenerating as-received XAD4 and XAD4-DMA, but not XAD4-TMA. Understanding phenol adsorption mechanisms allows development of physiochemically modified polymers with increased phenol adsorption capacity and regeneration efficiency.
Understanding phenol adsorption-desorption mechanisms allows adsorbent tailoring to improve capacity and adsorbent reuse.
Oil spills in marine environments have been comprehensively studied, while oil spills in freshwaters, which occur frequently, have received less attention. With an increase in the transport of…