Modeling of the sorption and diffusion processes of volatile organic air pollutants in grape fruits.

A mathematical model for the description of the sorption and diffusion processes of gaseous toluene and p-xylene in fruits of grape has been proposed. This model is based on the Fick's II low regarding a particle with a spherical shape (such as the berry of grapevine) and describes changes of air pollutant concentrations in different layers of the fruit, that is, the wax, peel, and pulp, during an exposure to contaminated air. The mass transfer coefficient and diffusion coefficients in the respective layers can be estimated using the experimental values. The theoretical data and the results from the exposure under steady-state laboratory conditions were compared and showed a good applicability of the proposed model for the prediction of volatile air pollutant partitioning in grape berries.

The sorption of airborne pollutants on natural and synthetic surfaces: correlation to the mathematical models

The laboratory experiments were carried out to study the sorption process of gaseous toluene in the peel of different fruits as well as in the chemically prepared material based on silica support (multiligand-adsorbent). For the sorption experiments, a vapor generating system was used that allows the exposure of sorbents to a constant flux of polluted air. The concentration of toluene in the tested sorbents was followed as a function of exposure time. The obtained results were correlated to the mathematical models describing the sorption kinetics in the leaves. The investigation with the plant material showed dual-phase behavior of the toluene partition ('mixed' sorption mechanism), in the case of multiligand-adsorbent a typical adsorption process was observed. Sorption kinetics to fruit material was well correlated to the two-compartment model, while for the chemically prepared material to the first-order model.

Volatile organic air contaminants in plants: Comparative investigations of toluene sorption in fruit and chemically modified adsorbents.

Comparative investigations of the sorption process of gaseous toluene were performed using fruit material (orange peel) and the mixture of chemically bonded phases (CBPs) as sorbents. For this study, a specially constructed system that allows exposure of sorbents to volatile air contaminants at constant concentrations was applied. The results for the prepared packings indicate a typical adsorption process described by Langmuir isotherm. In the case of orange peel, a mixed mechanism of the sorption process is suggested.

Determination of monocyclic aromatic hydrocarbons in fruit and vegetables by gas chromatography-mass spectrometry.

Monocylic aromatic hydrocarbons (MAHs: benzene, toluene, ehtylbenzene and xylenes) were isolated from fruit and vegetables using a solvent extraction technique. GC-MS (with selected-ion monitoring mode) was applied for determination of the isolated pollutants. It was observed that uptake of MAHs depends on the species and takes place in different morphological parts of the biological material. The highest concentrations of MAHs were found in parsley leaves (m- and p-xylene) and in orange peel (toluene). Estimation of the daily human exposure to MAHs through eating contaminated fruit and vegetables was performed.