Competitive Adsorption of Chloroform and Bromoform Using Commercial Bituminous and Coconut Based Granular Activated Carbons

Abstract

A study was made to compare efficiency and capacity of two types of granular activated carbon (GAC), Calgon F200 and Norit GCN1240, for removal of Trihalomethanes (THMs) in water and to examine the competition of one adsorbate in the presence of another. Coconut based Norit (GCN1240) and bituminous based Calgon F200 GACs were selected for the study. Multi-component adsorption isotherm models were established for both GACs using same model water containing chloroform (2.54 mg L^-1) and bromoform (1 mg L^-1). After sample bottles were agitated at the speed of 25 rpm in a mechanical shaker for 15 days, measurements were taken using gas chromatography. The results obtained were checked with Freundlich adsorption isotherm model. This model expresses well adsorption of one THM species in the presence of another with R² > 0.95. Based on the model, adsorption capacity of Calgon F200 and Norit GCN1240 were found higher for bromoform than chloroform. Calgon F200 showed a higher adsorption capacity compared to Norit GCN1240 for a lower equilibrium concentration (< 3 μg L^-1). However, for equilibrium concentrations in the range of 3 - 200 μg L^-1, both Calgon F200 and Norit GCN1240 showed similar capacity for competitive adsorption of THMs.
Keywords: Granular Activated Carbon; Adsorption; Bromoform; Chloroform; Trihalomethane