Reactive adsorption of SO2 on activated carbons with deposited iron nanoparticles

• Published in: Journal of hazardous materials 2013-02, Vol.246-247, p.300-309
• Main Authors: Arcibar-Orozco, Javier A., Rangel-Mendez, J. Rene, Bandosz, Teresa J.
• Format: Article
• Language: English
• Subjects: Activated carbon; Adsorption; Air Pollutants - isolation & purification; Applied sciences; Atmospheric pollution; Charcoal - chemistry; Chemical engineering; Desulfurization; Exact sciences and technology; Ferric Compounds - chemistry; Iron oxyhydroxides; Metal Nanoparticles - chemistry; Nanoparticles; Pollution; Reactive adsorption; Sulfur dioxide; Sulfur Dioxide - isolation & purification
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2012.12.001

[Display omitted] ► Prehumidification of carbon surface increases two and half times the uptake of SO2. ► H2SO4 is the product of SO2 reactive adsorption on the unmodified carbon surface. ► Iron species react with H2SO4 forming sulfates. ► Small iron nanoparticles enhanced adsorption by providing well-dispersed reactive centers. The effect of iron particle size anchored on the surface of commercial activated carbon on the removal of SO2 from a gas phase was studied. Nanosize iron particles were deposited using forced hydrolysis of FeCl3 with or without H3PO4 as a capping agent. Dynamic adsorption experiments were carried out on either dry or pre-humidified materials and the adsorption capacities were calculated. The surface of the initial and exhausted materials was extensively characterized by microscopic, porosity, thermogravimetric and surface chemistry. The results indicate that the SO2 adsorption capacity increased two and half times after the prehumidification process owing to the formation of H2SO4 in the porous system. Iron species enhance the SO2 adsorption capacity only when very small nanoparticles are deposited on the pore walls as a thin layer. Large iron nanoparticles block the ultramicropores decreasing the accessibility of the active sites and consuming oxygen that rest adsorption centers for SO2 molecules. Iron nanoparticles of about 3–4nm provide highly dispersed adsorption sites for SO2 molecules and thus increase the adsorption capacity of about 80%. Fe2(SO4)3 was detected on the surface of exhausted samples.