Absorption studies of aromatic compounds in aqueous solution onto activated carbons

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Date
2004
Authors
Faridah, Ghafar
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Abstract
The focus of this research was to investigate the removal of aromatic compounds; benzene, toluene and o-xylene from aqueous solutions by adsorption on commercial activated carbons; Norit GAC 1240 (N1240) and Calgon Filtrasorb 300 (F300). The experiments were conducted in batch and continuous systems. In a batch system, the operation parameters investigated were initial concentrations (60 – 600 mg/L for benzene; 60 – 480 mg/L for toluene and 30 – 150 mg/L for o-xylene); temperature (30 - 50C); pH of solutions (3 – 10) and contact time. In a continuous system, the parameters studied were initial concentrations (60 - 600 mg/L for benzene; 60 - 480 mg/L for toluene and 60 - 150 mg/L for o-xylene); flow rate (40 - 100 ml/min) and weight of adsorbent (3 and 6 g). In the batch system, the adsorption capacity of all adsorbate-adsorbent systems increased with increasing initial concentrations but decreased with temperatures. The equilibrium time was described in the following order: benzene > toluene > o-xylene. Adsorption isotherm studies using the Freundlich and Langmuir isotherm models indicated that the adsorption isotherms of benzene, toluene and o-xylene on both adsorbents; N1240 and F300 can be described by both isotherm models. The N1240 was found to exhibit higher adsorption capacity than F300 for all adsorbates due to its higher surface area and porosity. The pseudo second order kinetic model was found to be suitable to describe the adsorption kinetic of all adsorbate-adsorbent systems. Analysis of thermodynamic studies shows that the adsorption process was physical adsorption, spontaneous and exothermic in nature for all adsorbate-adsorbent systems. In the continuous system, the adsorption capacity of both adsorbates for all adsorbates increased with increasing initial concentration, flow rate and amount of adsorbent. Adam-Bohart and Yoon-Nelson kinetic models were suitable to represent the measured adsorption data well for all adsorbate-adsorbent systems. It was found that the adsorption capacities of both adsorbents in continuous system were higher than those in the batch system.
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Master
Keywords
Chemical Engineering , Aromatic Compund , Aqueous Solution
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