Pollution Research Paper

ADSORPTION ISOTHERM MODELS TEST BY ERROR FUNCTION ANALYSIS IN THE REMOVAL OF AROMATIC COMPOUNDS AND COLOUR USING ZELIAC

NURAZIM IBRAHIM, HAMIDI ABDUL AZIZ, AND MOHD SUFFIAN YUSOFF

Abstract

High concentrations of aromatic compounds in water sources physically intensify the colour and cause odour. More importantly, the reaction of this compounds with disinfectants during water treatment, produces toxic materials. Hence, the adsorption of aromatic compounds and colour in borehole water was examined using the new composite media, Zeliac. Batch adsorption experiments revealed that the maximum percentage removal of UV254 and colour were 86 % and 91 % respectively. Analysis of equilibrium sorption suggested the Langmuir isotherm as the most suitable model to describe the batch study data, with coefficients of determination (R2) of 0.8815 and 0.8373 for UV254 and colour, respectively. This finding was based on a comparison of isotherm models including the Langmuir, Freundlich, Dubinin–Raduskevich (DR), and Temkin models. In addition, validity test of the Langmuir and Freundlich isotherms using the separation factor (RL) and sorption intensity (n) indicated the favorable adsorption of UV254 and colour onto Zeliac. Mean while, the mean free energy (E)value computed from the DR isotherm, revealing that the adsorption process was physical in nature. Then, the isotherm models were analyzed using error function analysis to verify the validity of each linearized isotherm model and identify the best isotherm model that represent the experimental data. Among the tested models, the DR isotherm model had the lowest error, indicating that DR is the best model to represent this adsorption system. These results also suggest that physisorption was the dominant mechanism of UV254 and colour adsorption on Zeliac.