Novel Phenanthrene Sorption Mechanism by Two Pollens and Their Fractions

Abstract

A pair of pollens (Nelumbo nucifera and Brassica campestris L.) and their fractions were characterized by elemental analysis and advanced solid-state 13 C NMR techniques and used as biosorbents for phenanthrene (Phen). Their constituents were largely aliphatic components (including sporopollenin), carbohydrates, protein, and lignin as estimated by 13 C NMR spectra of the investigated samples and the four listed biochemical classes. The structure of each nonhydrolyzable carbon (NHC) fraction is similar to that of sporopollenin. The sorption capacities are highly negatively related to polar groups largely derived from carbohydrates and protein but highly positively related to alkyl carbon, poly-(methylene) carbon, and aromatic carbon largely derived from sporopollenin and lignin. The sorption capacities of the NHC fractions are much higher than previously reported values, suggesting that they are good sorbents for Phen. The Freundlich n values significantly decrease with increasing concentrations of poly(methylene) carbon, alkyl C, aromatic moieties, aliphatic components, and the lignin of the pollen sorbents, suggesting that aliphatic and aromatic structures and constituents jointly contribute to the increasing nonlinearity. To our knowledge, this is the first investigation of the combined roles of alkyl and aromatic moiety domains, composition, and accessibility on the sorption of Phen by pollen samples.

Composition and structure of natural organic matter through advanced nuclear magnetic resonance techniques

“…The two pollens (Nelumbo nucifera and Brassica campestris L.) were sequentially fractionated into the lipid (LP), lipid free (LF), residue obtained after successive TFA hydrolysis (TFAR), residue obtained after saponification (SR), and acid nonhydrolyzable carbon (NHC) to obtain the refractory component, as described elsewhere [53]. In brief, the lyophilized OS samples were extracted to separate lipids via Soxhlet extraction with CH 2 Cl 2 :CH 3 OH (2:1, v/v) for 24 h. The LP fractions were dried at 60 °C.…”

“…The cross polarization (CP) experiments included 13 C cross polarization/total sideband suppression (CP/TOSS), CP/TOSS plus dipolar dephasing (CP/TOSS/DD), and Figure S1). A pair of spectral editing techniques, dipolar dephasing, and 13 C CSA were employed to study the structures of the bulk pollens and their fractions in more detail [53].…”

Importance of Sporopollenin Structure and Accessibility in the Sorption of Phenanthrene by Biota Spores and Pollens

“…Because airborne pollens and fungal spores are not only generated in great abundance but also transported to high altitudes and for long distances, they are significant media for the global transportation of air pollutants. Recently, the observed organic carbon-normalized sorption coefficient ( K oc ) of phenanthrene (Phen) for the pollen fractions reached up to 670 000 mL/g . Moreover, spores/pollens can act as CNN or ice nuclei to form cloud droplets. , Furthermore, a portion of these particles was deposited on water and land by wet precipitation and were well preserved in millions of years of strata, with full retention of their morphology in the form of fossil spores (sporopollenins) .…”

“…Moreover, sporopollenins could also be a cost- and energy-saving alternative to activated carbon to remove environmental contaminants such as pesticides, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls from different sources such as waste water, soil, and sediments . However, only two studies have been conducted on sporopollenins for the removal of hydrophobic organic contaminants (HOCs). , Although structures of sporopollenins from various lower and higher plant species have been investigated in previous studies, − the role of the structures in the sorption of HOCs has not been examined. Moreover, there is a relative dearth of quantitative information available regarding spore/pollen-based sorption of hydrocarbon substances.…”

“…Numerous investigators have reported that the chemical structure, microporosity, and polarity of natural organic matter (NOM) influence the sorption capacities of HOCs. ,− Whether the aliphaticity or aromaticity of NOM is related to the sorption capacities of HOCs is still controversial . Previous studies have indicated the important role of the aromatic domains of NOM in the sorption affinities of HOCs. , However, the significant contribution of the aliphatic moieties of NOM in the interaction with HOCs has been emphasized in many studies. ,, The mobile (CH 2 ) n -type aliphatic structures in NOM could be derived from resistant biopolymers .…”