Multicomponent Organic Compounds Adsorption/Desorption Model for Prediction of the Lifetime of a Charcoal Filter

Abstract

In an attempt to predict the lifetime of a charcoal filter designed to remove gaseous organic compounds, a model was developed to simulate adsorption and desorption of multicomponent organic compounds in the filter. The model is composed of a mass balance equation and adsorption/desorption rate equations. When a charcoal filter is installed in a cleanroom airconditioning system, numerous types of organic compounds are competitively adsorbed onto adsorption sites (pores) of the activated carbon on the filter, which leads to displacement adsorption phenomenon. In order to consider this phenomenon in lifetime prediction, the adsorption/desorption rate equations are designed to express the concept that organic compounds of different types share or compete with each other for the limited number of adsorption sites. In this model, adsorption/desorption characteristics of each organic compound are represented by multiple parameters. A method was also proposed to estimate parameter values of organic compounds with unknown properties. In this method, the simulation model considers the total organic compound detected by means of gas chromatography (GC) analysis of cleanroom air sampled upstream of the charcoal filter. This newly developed simulation model was validated by comparing simulated and measured adsorption breakthrough curves for a multicomponent system. A charcoal filter with honeycomb-structure media was used in this validation. Simulated values were found to be in agreement with the measured values, which demonstrates that this simulation model is valid.

Citric acid-modified carbon chemical filtration for cleanroom air quality control: Study on N-methyl-2-pyrrolidone and the interference of co-existing toluene

“…To promote gas absorption, the porous activated carbons are frequently modified with either acids for the absorption of basic gases, or bases for the absorption of acidic gases. [15][16][17][18] Strong organic bases containing ammonia and amines were known to be effectively removed by ion exchange resins and acid-modified activated carbons 19,20 through chemisorption mechanisms mainly involving strong interactions between the contaminant molecules and the surface active sites. Despite that introducing acids to activated carbon could extend the number of oxygen functional groups such as O-H, C ¼ O and C-OH on materials' surface for adsorption efficiency improvements, [21][22][23] the molecular formula of citric acid (CA), HOOC-CH 2 -COH(COOH)-CH 2 -COOH, indicates that it is rich in carboxylic acid for sustaining favourable acid-base reactions.…”