VOCs physisorption on micro–mesoporous solids: Application for dichloroethylene, trichloroethylene, and tetrachloroethylene on SiO2 and Ag/SiO2

• Micro–mesoporous SiO2 and Ag-doped SiO2 are tested for chloroalkene adsorption.
• Texture of SiO2 and Ag/SiO2 materials is assessed from N2 sorption isotherms.
• FTIR bands of SiO2 solids with and without adsorbed dichloroethylene are analyzed.
• Freundlich equation is found to fit CXHYClZ adsorption on silica.
• Interaction of chloroalkenes and SiO2 is measured via isosteric heat of adsorption.

An experimental physisorption study on the adsorption of chloroalkenes (CXHYClZ), such as dichloroethylene, trichloroethylene and tetrachloroethylene, on SiO2 and Ag-doped SiO2 micro–mesoporous solids is performed. The existence of the adsorbed phase is assessed by observing the position of the incumbent FTIR chloroalkene vibration bands. The SiO2 substrates are prepared from the reaction of tetraethyl orthosilicate and water in the presence of ethanol. Adsorption of CXHYClZ compounds on the pristine and Ag-doped SiO2 samples is measured in the temperature range 408–523 K by a chromatographic method. The uptake degree of the chlorinated compounds results to be temperature dependent, and the Freundlich adsorption model is found to fit the CXHYClZ adsorption data. The degree of interaction between these molecules and the SiO2 samples is analyzed through evaluation of the isosteric heat of adsorption of C2H2Cl2 at different sorption loadings on the SiO2 and Ag/SiO2 substrates. This heat is found to fulfill the following decreasing order: SiO2 > Ag/SiO2 (2 wt.% Ag) > Ag/SiO2 (10 wt.% Ag) > Ag/SiO2 (5 wt.% Ag).

An experimental physisorption study on the adsorption of dichloroethylene, trichloroethylene and tetrachloroethylene on SiO2 and Ag-doped SiO2 micro–mesoporous solids is performed in the range of temperatures 408–523 K.Figure optionsDownload as PowerPoint slide