ADSORPTION OF PHENOL BASED ORGANIC POLLUTANTS ON ACTIVATED CARBON FROM MULTICOMPONENT DILUTE AQUEOUS-SOLUTIONS

Five organic phenolic compounds (phenol, o-chlorophenol, m-chloropheno l, p-chlorophenol and m-cresol) hale been used to determine the adsorp tion isotherms for single and bisolute systems from dilute aqueous sol utions on activated carbon. An experimental technique for the analysis of the equilibrium concentration of a bisolute in aqueous solutions u sing a UV spectrophotometer has been successfully developed and employ ed. Experimental data were obtained by conducting experiments in a sha ker-incubator at 30 C (local average ambient temperature). All common types of reported isotherms, including Langmuir. Freundlich, BET (Brun auer, Emmett and Teller) and empirical types, were tried. For single s olute systems the experimental data were found to be best represented by the Freundlich isotherm for all cases except for phenol, which foll owed the Langmuir isotherm. For bisolute systems, the coefficients for all the most commonly used models were determined accurately applying a modified Rosenbrock method for non-linear optimization. The present and previous published experimental data and predicted model results have been analysed statistically to validate the applicability of the models. The generalized and empirical models have shown a better fit t han the other most commonly used models (Langmuir and Freundlich). The empirical model has minimal error between predicted and experimental values due to more constants in the expression as compared to the gene ralized model, The generalized model has a unique characteristic, cove ring both extremes, Langmuir as well as Freundlich type isotherms, and could represent all types of data for multi-component systems with fe wer coefficients with almost the same degree of accuracy as the empiri cal model. (C) 1997 Elsevier Science Ltd.