Dibenzodioxin Adsorption on Inorganic Materials

Abstract

Dibenzodioxin adsorption/desorption on solid surfaces is an important issue associated with the formation, adsorption, and emission of dioxins. Dibenzodioxin adsorption/desorption behaviors on inorganic materials (amorphous/mesoporous silica, metal oxides, and zeolites) were investigated using in situ FT-IR spectroscopy and thermogravimetric (TG) analysis. Desorption temperatures of adsorbed dibenzodioxin are very different for different kinds of inorganic materials: ∼200°C for amorphous/mesoporous silica, ∼230°C for metal oxides, and ∼450°C for NaY and mordenite zeolites. The adsorption of dibenzodioxin can be grouped into three categories according to the red shifts of the IR band at 1496 cm -1 of the aromatic ring for the adsorbed dibenzodioxin: a shift of 6 cm -1 for amorphous/mesoporous silica, a shift of 10 cm -1 for metal oxides, and a shift of 14 cm -1 for NaY and mordenite, suggesting that the IR shifts are proposed to associated with the strength of the interaction between adsorbed dibenzodioxin and the inorganic materials. It is proposed that the dibenzodioxin adsorption is mainly via the following three interactions: hydrogen bonding with the surface hydroxyl groups on amorphous/mesoporous silica, complexation with Lewis acid sites on metal oxides, and confinement effect of pores of mordenite and NaY with pore size close to the molecular size of dibenzodioxin.

Importance of PCDD/F molecules’ polarizability and steric hindrance on their adsorption onto zeolites in a standard EN1948-1 sampling device for incinerator emission monitoring

“…The external surface of both zeolites is an oxygen-terminated, hydroxylated and partially water saturated polar surface (see scheme 1 showing interaction between adsorbed DD dioxin and zeolite in ref. [24]). So, it can be assumed that the outer surfaces of both crystals have quasi-identical physical-chemical properties.…”

“…Jäger et al demonstrated a selective adsorption of dioxins onto zeolites, with dioxins thermally desorbed from incineration ashes [19]. Adsorption properties of dioxins onto zeolites and energy of desorption were determined by temperature programmed desorption (TPD) due to dioxin low volatility [20][21][22][23][24].…”

Selective adsorption of 2,3-DCDD and 1,2,3,4-TCDD on *BEA, EMT, FAU and MFI-type zeolites as alternative adsorbents for on-line dioxin monitoring

“…Xi et al (2003) demonstrated that the nature of the cations trapped in the pores of zeolite could have an influence on the adsorption of dibenzofuran (zeolite framework not specified). Yang et al (1999) found that dibenzodioxin was thermally desorbed at 241°C from Y zeolite (FAU-structure type with Si/Al = 195), whereas Guan et al (2005) showed that the desorption temperature of dibenzodioxin adsorbed on NaY zeolite with Si/Al = 6 is about 450°C.…”

Experimental study of the zeolite affinity for the dioxin adsorption for a new direct and on-line measurement method

“…Thus, trapped dioxins amount will increase according to the selectivity of zeolites. Another characteristic of these materials is their capacity of thermal desorption due to mechanical resistance versus temperature: some zeolitic materials can be heated up to 600°C [7].…”