Research On The Factors Affecting The Adsorption Of Siloxanes On Activated Carbon

With the fast increasing of municipal solid waste (MSW), landfilling has become the main method to dispose of large amount of MSW. Along with the landfilling process, large amount of landfill gas (LFG) with abundant CH4would be produced. High CH4content brings LFG high recoverable value. However, siloxane, a kind of trace component is LFG, is one of the main disadvantage in the recoverable process of LFG.The main content of this paper is discussing how the textural parameters influence adsorption of siloxanes through testing siloxanes adsorption capacity of activated carbons with different textural parameter. Then we treated a selected activated carbon with hydrochloric acid, ammonium hydroxide and thermal N2, aiming to gain the best treating method which can improve siloxanes adsorption capacity of activated carbons mostly. At last, the treated activated carbons were characterized by using N2adsorption and Boehm titration. The relationship between siloxanes adsorption capacity and physical and chemical properties of activated carbons was analysed. We wanted to provide some theoretical evidence for the industrial application of activated carbon adsorbing siloxanes.In this study, model gas with a certain concentration of octamethylcyclotetrasiloxane (D4)/decamethylcyclopentasiloxane (D5) produced in lab was used in dynamic adsorption experiments of activated carbon. D4/D5concentration in treated gas was tested through timing sampling. D4/D5adsorption capacity at penetration time was caculated. The main conclusions of this study are as follows: 1. D4adsorption on activated carbons mainly occurs in pores with diameter increasing between1.7nm and5nm.2. Basicity of activated carbon was increased after ammonium hydroxide treatment and thermal disposal in N2. Oxygenous acid functional groups on activated carbon were increased after hydrochloric acid treatment. Volume of pores with diameter between1.7nm and5nm was increased after all the three treating methods above.3. High basicity of activated carbon could promote D4adsorption on it. Plenty acid functional groups reduced D4adsorption capacityof activated carbons.4. Existence of steam dramatically decreased D4adsorption capacity of activated carbon. And the higher the humidity, the larger the decreasing amount of D4adsorption capacity. Existence of CO2slightly decreased D4adsorption capacity of activated carbon.5. D5adsorption charateristics on activated carbons were similar to D4. The adsorption of D5also happened in pores with diameter between1.7nm and5nm. Plenty oxygenous acidic functional groups would also reduce the adsorption capacity of D5on activated carbons.