Sorption of 1-naphthol by plant cuticular fractions
CHEN Bao-liang , LI Yun-gui
DOI:
Received December 28, 2006,Revised March 18, 2007, Accepted , Available online
Volume 19,2007,Pages 1214-1220
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The contribution of aliphatic-rich plant biopolymer to sorption of hydrophobic organic compounds is significantly important because
of their preservation and accumulation in the soil environment, but sorption mechanism is still not fully understood. In this study,
sorption of 1-naphthol by plant cuticular fractions was examined to better understand the contributions of respective fraction. Toward
this end, cuticular materials were isolated from the fruits of tomato by chemical method. The tomato cuticle sheet consisted of waxes
(6.5 wt%), cuticular monomer (69.5 wt%), and polysaccharide (24.0 wt%). Isotherms of 1-naphthol to the cuticular fractions were
nonlinear (N value (0.82 – 0.90)) at the whole tested concentration ranges. The Koc/Kow ratios for bulk cuticle (TC1), dewaxed cuticle
(TC2), cutin (TC4), and desugared cuticle (TC5) were larger than unity, suggested that tomato bulk cuticle and cutin are much powerful
sorption medium. Sorption capability of cutin (TC4) was 2.4 times higher than the nonsaponifiable fraction (TC3). The 1-naphthol
interactions with tomato cuticular materials were governed by both hydrophobic-type interactions and polar (H-bonding) interactions.
Removal of the wax and polysaccharide materials from the bulk tomato cuticle caused a significant increase in the sorption ability of
the cuticular material. There was a linear negative trend between Koc values and the amount of polysaccharides or fraction’s polarities
((N+O)/C); while a linear positive relationship between Koc values and the content of cutin monomer (linear R2 = 0.993) was observed
for present in the cuticular fractions. Predominant sorbent of the hydrophobic organic compounds (HOCs) in the plant cuticular fraction
was the cutin monomer, contributing to 91.7% of the total sorption of tomato bulk cuticle.
