EQUILIBRIUM ADSORPTION STUDIES OF SOME AROMATIC POLLUTANTS FROM DILUTE AQUEOUS-SOLUTIONS ON ACTIVATED CARBON AT DIFFERENT TEMPERATURES

Aqueous solutions of phenol, p-chlorophenol, and p-nitrophenol have be en used to determine the adsorption isotherm for single solute systems on activated carbon at different temperatures. The experimental progr am has been conducted to investigate the influence of concentration an d temperature. All the reported equilibrium isotherm equations have be en tried on present and published experimental data. A generalized iso therm equation which was proposed by Khan et al. (6, 10) and tested fo r bi-solute adsorption data has been modified for single-solute system . The temperature dependency has also been incorporated into a general ized equation. It has been noticed that the Radke and Prausnitz (7) an d generalized isotherm equations could represent the entire data with a minimum average percentage error. The influence of different adsorbe nts, sorbate concentrations, and pH of aqueous solutions has also been discussed in detail. The temperature dependency has been investigated using both the Dubinin-Astakov(13) and the modified generalized equat ion. The generalized equation describes the experimental and published data adequately and provides a single value of differential molar hea t of adsorption, Delta H-ads, for a single solute adsorption system. T he Dubinin-Astakov isotherm equation has shown an increasing trend of Delta H-ads as the loading of adsorbent has increased. (C) 1997 Academ ic Press.