Ammonia Removal Using Activated Carbons: Effect of the Surface Chemistry in Dry and Moist Conditions

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• 作者：Maraisa Gon莽alves ; Laura S谩nchez-Garc铆a ; Erika de Oliveira Jardim ; Joaqu铆n Silvestre-Albero ; Francisco Rodr铆guez-Reinoso
• 刊名：Environmental Science & Technology
• 出版年：2011
• 出版时间：December 15, 2011
• 年：2011
• 卷：45
• 期：24
• 页码：10605-10610
• 全文大小：808K
• 年卷期：v.45,no.24(December 15, 2011)
• ISSN：1520-5851

文摘

The effect of surface chemistry (nature and amount of oxygen groups) in the removal of ammonia was studied using a modified resin-based activated carbon. NH₃ breakthrough column experiments show that the modification of the original activated carbon with nitric acid, that is, the incorporation of oxygen surface groups, highly improves the adsorption behavior at room temperature. Apparently, there is a linear relationship between the total adsorption capacity and the amount of the more acidic and less stable oxygen surface groups. Similar experiments using moist air clearly show that the effect of humidity highly depends on the surface chemistry of the carbon used. Moisture highly improves the adsorption behavior for samples with a low concentration of oxygen functionalities, probably due to the preferential adsorption of ammonia via dissolution into water. On the contrary, moisture exhibits a small effect on samples with a rich surface chemistry due to the preferential adsorption pathway via Br酶nsted and Lewis acid centers from the carbon surface. FTIR analyses of the exhausted oxidized samples confirm both the formation of NH₄⁺ species interacting with the Br酶nsted acid sites, together with the presence of NH₃ species coordinated, through the lone pair electron, to Lewis acid sites on the graphene layers.