Pyrene Sorption by Natural Organic Matter

Abstract

Sorption of pyrene on various types of natural organic matter (NOM) varying in chemical composition (e.g. high aliphaticity or aromaticity) was examined in batch sorption studies. The NOM samples (cuticle, humin, humic acid, degraded lignin, peat and lignite) were characterized by elemental analyses and solid-state 13 C NMR spectra. Previous studies on polycyclic aromatic hydrocarbons (PAHs) sorption on soils and sediments led to the conclusion that aromatic component of the NOM determines the binding of nonionic compounds and that the polarity of the NOM reduces the binding coefficient of the aromatic NOM moieties. In this study we tested the hypothesis that aliphatic moieties of NOM derived from soils or sediments can contribute significantly to the binding of PAHs in aqueous media. Cuticle and a humin sample from an algal deposit exhibited the highest distribution coefficients (K oc ). Both samples were rich in aliphatic structures and had very low aromaticity (4.6 and 8.8% for cuticle and humin samples, respectively). A positive trend was observed between the K oc level and the aliphaticity of the NOM, calculated from the 13 C NMR spectra. This study demonstrates that aliphatic NOM compounds significantly sorb pyrene in aqueous solution, thus leading to the conclusion that the contribution of these groups to the sorption of aromatic nonionic pollutants in complex NOM matrices can be significant.

Role of extractable and residual organic matter fractions on sorption of phenanthrene in sediments

“…The latter possibility seems to be supported by the occurrence of N-containing compounds (average N $ 3.2%) in the LG isolates, which were supposed to contain no N. However, for the degraded lignin, amid functional groups can be added to the aromatic carbon in lignin during humification (Schmidt-Rohr et al, 2004). Moreover, the contents of C and O in the LG isolates were much close to the values for the reported lignin in the other studies, while H contents were slightly higher than their values (Xing et al, 1994;Chefetz et al, 2000;Wang et al, 2007b;Yang et al, 2010). Furthermore, a van Krevelen diagram (Fig.…”

“…The Phen sorption on the LG fractions did not exhibit strong nonlinearity, due in part to its aliphatic component. In contrast, nonlinear sorption (n = 0.80, 0.63) by an extracted lignin and a degraded lignin had been found in other studies (Chefetz et al, 2000;LeBoeuf and Weber, 2000). The variation in the nonlinearity of Phen sorption by lignin could be due in part to the different lignin sources, extraction methods, and sorption experiment approaches.…”

“…This is similar to findings by Kohl and Rice (1999) who used lipid free soil as sorbent. Another frequently investigated biopolymer is lignin because of its relatively high aromaticity and high abundance among natural biopolymers (Chefetz et al, 2000). Wang et al (2007a) found that the sorption isotherms of Phen and pyrene on a commercial lignin were almost linear, with the n value of 0.96 and 0.94, respectively.…”

“…Wang et al (2007a) found that the sorption isotherms of Phen and pyrene on a commercial lignin were almost linear, with the n value of 0.96 and 0.94, respectively. In contrast, pyrene displayed a strong nonlinear sorption isotherm on a degraded lignin (Chefetz et al, 2000). Gunasekara et al (2003) observed that Phen sorption isotherms were more linear on bleached humic acids that had lignin removed structurally than on the corresponding untreated humic acids.…”

Sorção do herbicida acetochlor em amostras de solo, ácidos húmicos e huminas de argissolo submetido à semeadura direta e ao preparo convencional

“…Os grupos oxigenados mais abundantes nesta fração contribuiriam para as reações da MO com o acetochlor por meio de pontes de H, assim como a maior presença de grupos alifáticos estimularia a retenção do produto por meio de interações hidrofóbicas. Chefetz et al (2000) verificaram para sorção de compostos hidrofóbicos em huminas valores de K OC 10 vezes superiores aos obtidos em ácidos húmicos. Naquele trabalho, a maior proporção de grupamentos alifáticos em huminas, determinada por espectroscopia de RMN 13 C, e a relação direta entre K OC e grau de alifaticidade obtida para os diferentes sorventes comprovaram a importância de estruturas alifáticas no processo de sorção.…”