Comparative Batch and Column Evaluation of Thermal and Wet Oxidative Regeneration of Commercial Activated Carbon Exhausted with Synthetic Dye

Abstract

The efficiency of regenerated spent commercial activated carbon for synthetic dye removal was studied using thermal and wet oxidative regeneration methods. Two types of experiments were carried out, batch adsorption experiments and continous flow (fixed bed) column experiment to study the mechanism of dye removal by the commercial activated carbon. The adsorption equilibrium data were tested using two isotherm models; Langmuir and Freundlich. The goodness of fit of the models to the experimental data was estimated from the three error criteria; R², SSE and SE which follow the order for the two models according to best fit; Langmuir (0.959) > Freundlich (0.901), Langmuir (3.889 and 3.118) < Freundlich (9.449 and 4.860).The theoretical maximum adsorption capacity of the virgin commercial carbon (q_max = 64.10mgg^-1) was compared with those obtained for thermal regeneration method (q_max = 61.73mgg^-1) and wet oxidative method (q_max = 53.72mgg^-1). It was in closer agreement with the thermal method than the wet method. The %regeneration efficiency (RE) of the two methods were compared and the thermal method had higher RE (96.30%) than the wet regeneration method with R.E of 83.80%. The column Breakthrough adsorption capacity (q_b) of the commercial activated carbon was 18.52mgg^-1 which represented 28.89% of the theoretical maximum adsorption capacity of the adsorbent. From the results, the methods compared favourably with those of commercially activated carbon.