Suppression of Dioxin Emission in Co-Incineration of Polyfvinyl Chloride) with TiO_2-Encapsulating Polystyrene

摘要

This paper presents an approach to the suppression of the emission of dioxin and its precursors as a result of the co-incineration of poly(vinyl chloride) (PVC) with TiO_2-encapsulating polystyrene (TEPS), in which TiO_2 nanoparticles with the capacity to adsorb dioxin and its precursors are encapsulated without significant agglomeration. Field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were used to show that spherical PS particles encapsulating a uniform dispersion of TiO_2 nanoparticles are obtained through the dispersion polymerization of styrene in an aqueous ethanol medium. To facilitate the encapsulation, the surface of the TiO_2 nanoparticles was modified with a polymerizable organic silane linker prior to polymerization. For comparison purposes, experiments were performed in which PVC was co-incinerated with neat PS (PVC/PS), TiO_2-encapsulating PS (PVC/TEPS), and mechanically mixed TiO_2/PS (PVC/PS-MTiO_2). Qualitative and quantitative investigations of the suppression of the emission of a model dioxin and its precursors were performed by analyzing the exhaust gases from the co-incinerations using gas chromatography/ mass spectrometry (GC/MS). The results show that the addition of TiO_2 nanoparticles into co-incineration systems reduces the concentration of the dioxin and its precursors in exhaust gases. Moreover, the quantitative removal efficiencies for PVC/TEPS and PVC/PS-MTiO_2 indicate that the suppression is successfully enhanced by the TiO_2-encapsulation: increases in the dispersity of the nanoparticles result in improved adsorption of the dioxin and its precursors.