Biogas Purification: A Comparison of Adsorption Performance in D4 Siloxane Removal Between Commercial Activated Carbons and Waste Wood-Derived Char Using Isotherm Equations

Abstract

Biogas production from organic waste could be an option to reduce landfill and pollutant emissions into air, water, and soil. These fuels contain several trace compounds that are crucial for highly efficient energy generators or gas injection into the grid. The ability of adsorbents to physically remove such adsorbates was investigated using adsorption isotherms at a constant temperature. We experimentally modelled isotherms for siloxane removal. Siloxanes were considered due to their high impact on energy generators performance even at low concentrations. Octamethylcyclotetrasiloxane was selected as a model compound and was tested using commercially available carbon and char derived from waste materials. The results show that recyclable material can be used in an energy production site and that char must be activated to improve its removal performance. The adsorption capacity is a function of specific surface area and porous volume rather than the elemental composition. The most common adsorption isotherms were employed to find the most appropriate isotherm to estimate the adsorption capacity and to compare the sorbents. The Dubinin-Radushkevich isotherm coupled with the Langmuir isotherm was found to be the best for estimating the adsorption capacity.

Thermal Activation of Digested Sewage Sludges for Carbon Dioxide Removal from Biogas

“…The carbon dioxide capacity was determined by monitoring the response of the fixed-bed column with a simulated biogas blend (35% CO 2 and 65% CH 4 ) and identifying the breakthrough time from the data recorded by the mass spectrometer. The co-adsorption effects, like acid gasses (e.g., hydrogen sulphide) and siloxanes [42,43] The biogas flow rate and the GHSV were not changed during the experimental activity; for this reason, their influence on the adsorption capacity was not examined in the current work. The carbon dioxide adsorption capacity was computed using the following equation: 22.4 l mol is the molar volume of an ideal gas; -m sorb (g) is the mass of the sorbent; -10 6 is the unit conversion from ppmv to molar concentration.…”

“…The carbon dioxide capacity was determined by monitoring the response of the fixed-bed column with a simulated biogas blend (35% CO2 and 65% CH4) and identifying the breakthrough time from the data recorded by the mass spectrometer. The co-adsorption effects, like acid gasses (e.g., hydrogen sulphide) and siloxanes [42,43] have not been kept into account in the current study. Other relevant parameters for the adsorption tests are the following:…”

H2S Removal with Sorbent Obtained from Sewage Sludges

“…Porosity and surface chemistry, coupled to operating conditions (relative humidity, H 2 S concentration, O 2 concentration, presence of other contaminants in biogas stream, and temperature) are the main characteristics that involve the gas cleaning mechanisms [14][15][16][17][18][19][20][21][22].…”

Adsorption and Separation of the H2O/H2SO4 and H2O/C2H5OH Mixtures: A Simulated and Experimental Study

“…Some of their main characteristics for use as adsorbents are: selectivity on the element (molecule) that it is desired to adsorb or retain on its surface, great adsorption capacity (many pores), and the ability to withstand high temperatures for regeneration. There are many works found on the used of zeolites to adsorb water molecules [1][2][3][4][5][6][7][8][9][10][11]. In particular, García-Soto et al [12] presented an experimental study of a Na-A synthetic zeolite used for separation of the H 2 O/C 2 H 5 OH mixture, at temperatures of 120 and 140 • C , and at each of them different compositions by weight of ethanol: 50%, 60%, 70%, 80%, 85%, 90%, 95%, 97%, and 99%.…”