H2S Loss through Nalophan™ Bags: Contributions of Adsorption and Diffusion.

Lidia Eusebio,Laura Capelli,Selena Sironi

doi:10.1155/2017/9690704

Abstract

Hydrogen-sulfide (H2S) is a molecule of small dimensions typically present in the odor emissions from different plants. The European Standard EN 13725:2003 set a maximum storage time allowed of 30 hours, during which the sampling bag has to maintain the mixture of odorants with minimal changes. This study investigates the H2S losses through Nalophan bags and it shows that nonnegligible losses of H2S can be observed. The percent H2S loss after 30 hrs with respect to the initial concentration is equal to 33% ± 3% at a relative humidity of 20% and equal to 22% ± 1% at a relative humidity of 60%. The average quantity of adsorbed H2S at 30 h is equal to 2.17 105 gH2S/gNalophan at a storage humidity of 20% and equal to 1.79 105 gH2S/gNalophan at a storage humidity of 60%. The diffusion coefficients of H2S through Nalophan, for these two humidity conditions tested, are comparable (i.e., 7.5 10−12 m2/sec at 20% humidity and 6.6 10−12 m2/sec at 60% humidity).

Highlights

Odors do not have a direct effect on human health, they are considered one of the main causes of discomfort for the population living in areas impacted by odor emissions
This study investigates the H2S losses through Nalophan bags and it shows that nonnegligible losses of H2S can be observed
The experiments described in this paper aim to investigate the relative contributions of the two phenomena causing H2S loss in Nalophan bags, that is, adsorption and diffusion

Summary

Introduction

Odors do not have a direct effect on human health, they are considered one of the main causes of discomfort for the population living in areas impacted by odor emissions. The standard methodology for odor concentration measurement is a sensorial technique, that is, dynamic olfactometry [2], which is commonly applied for testing odors for environmental management purposes [3]. This technique is based on the sensation caused by an odorous sample directly on a panel of human assessors [4]. Performing olfactometric analyses on site presents some difficulties. In order to regulate the quality of the olfactometric analysis, the European Standard on dynamic olfactometry [2] defines the requirements for the materials used for sampling equipment. The requirements determined by the EN13725 for the olfactometry materials are as follows: being odorless and being able to minimize the physical or chemical interaction between sample components and sampling materials and having low permeability in order to minimize sample losses caused by diffusion and smooth surface

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Conclusion