Modeling of pollutant degradation inside 3D reconstructed porous soil structures using plasma technology

Abstract

<p>A Dielectric Barrier Discharge (DBD) plasma reactor is modelled during soil remediation process. In this study we investigate the antibiotic degradation by highly reactive species that are created, when a nanosecond pulse is applied. Antibiotics are lately drawing much attention due to their highly concentration and persistency in soil ground. In addition, antibiotics transport enhances the need for immediate soil remediation. In this study, different soils are computationally reconstructed based on either random stochastic (such as Monte Carlo technique) or grid arrangement algorithms. Monte Carlo technique that is currently used is for randomly generated spheres with the constrain of non-overlapping spheres. On the other hand, structures based on grid arrangements are developed using equally sized spheres, creating structures according to FCC (face center cubic) packing and for the denser structures non-equally sized spheres are used according to HCP (hexagonal close packed). The structures that are regenerated through this process offer 3D computer representations, where plasma physics and mass transport models, using COMSOL Multiphysics&#174; are applied. Emphasis is placed on plasma generation inside porous structures. Parameters such as soil porosity (dense or sparse medium) and electric mobility (characteristic parameter for ionized species transport) are estimated inside multiple soil structures. The models show that soil porosity and mobility do affect the plasma generation inside pores. In addition, during plasma generation (i.e. ionized species creation) the oxidized species that are responsible for antibiotic degradation (for instance Ozon, Nox etc.) are estimated and introduced in a macroscopic model for solving the mass and reaction problem. Pollutant degradation curve is estimated for the case of Ozone, where Ozone species (from plasma model inside porous soil) react with the antibiotic molecules. According to these calculations, antibiotic degradation caused by Ozone species inside the porous soil is estimated at one fifth of the total degradation.</p>