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Abstract: The activated carbon was prepared from carbonaceous agriculture waste Parthenium hysterophorous by chemical activation using concentrated H2SO4 at 130±5°C. The prepared activated carbon was characterized and was found as an effective adsorbent material. In order to test the efficacy of parthenium based activated carbon (PAC), batch experiments were performed to carryout the adsorption studies on PAC for the removal of highly toxic pollutant p-cresol from aqueous solution. The p-cresol adsorption studies were also carried out on commercial grade activated carbon (AC) to facilitate comparison between the adsorption capabilities of PAC and AC. For PAC and AC, the predictive capabilities of two types of kinetic models and six types of adsorption equilibrium isotherm models were examined. The effect of pH of solution, adsorbent dose and initial p-cresol concentration on adsorption behaviour was investigated, as well. The adsorption on PAC and on AC was found to follow pseudo-first order kinetics with rate constant 0.0016min−1 and 0.0050min−1, respectively. The highest adsorptive capacity of PAC and AC for p-cresol solution was attained at pH 6.0. Further, as an adsorbent PAC was found to be as good as AC for removal of p-cresol upto a concentration of 500mg/l in aqueous solution. Freundlich, Redlich–Peterson, and Fritz–Schlunder models were found to be appropriate isotherm models for PAC while Toth, Radke–Prausnitz and Fritz–Schlunder were suitable models for AC to remove p-cresol from aqueous solution. [Copyright &y& Elsevier]

Batch studies were carried out for studying the adsorption behaviour of phenol and 4-nitrophenol on granular activated carbon from a basal salt medium (BSM) at pH ≈7.1 and temperature ≈30°C. The literature review was done in order to review the information for comparison purposes on equilibrium models of phenol and 4-nitrophenol adsorption on activated carbon. The units for measurements reported in these models were found to be diverse, thus making the comparison difficult. These units have been converted into similar units for easy reference. In all, six models of Freundlich, Langmuir, Redlich–Peterson, Radke–Prausnitz, Toth and Fritz–Schlunder as reported in the literature have been fitted to the data of phenol/activated carbon and 4-nitrophenol/activated carbon systems of the present studies using nonlinear regression technique. Based on maximum deviations and correlation coefficients, Langmuir gave the poorest fit for both compounds; Redlich–Peterson, Radke–Prausnitz, and four parameter model of Fritz–Schlunder could represent the data with similar accuracy, i.e. with R 2-value of 0.98 and maximum deviation ≈12%. However, for phenol, two parameter model of Freundlich may be recommended because of ease in its parameter estimation and better accuracy. 4-Nitrophenol was found to be more adsorbed than phenol, which is consistent with the result found in literature. The kinetics of the adsorption was found to be intra-particle diffusion controlled with diffusion coefficient values of the order of 10−13 m2/s. Three distinct phases of kinetics – rapid, medium, and slow – have been observed in this study. [Copyright &y& Elsevier]