Effective adsorption of anionic dye, Orange G, from aqueous solutions onto activated carbon derived from saw dust by chemical activation with perchloric acid

Present communication addressed the applicability of a low cost activated carbon derived from 'perchloric acid activated saw dust' as an alternate for the contemporary expensive methods for the removal of anionic textile dye from aqueous solutions. Dynamic batch mode operation was set up for the study of various factors such as pH, contact time and temperature, affecting the removal of dye. The surface characterization of the activated carbon was carried out by Fourier transform infrared (FTIR). The process of removal was found to be fast and equilibrium was established in 50 min. The maximum removal obtained was 95.67% at pH 2.0, temperature 30 degrees C, 50 mg L-1 initial concentration and a 10 g/L of adsorbent dose. The kinetic study reveals that the data was in close agreement with pseudo-second order than pseudo-first order expression. Equilibrium isotherm was analyzed by fitting the data into Langmuir and Freundlich models. The data are better fitted by Freundlich isotherm as compared with Langmuir. The calculated adsorption capacity of activated carbon was 64.93 mg/g at 30 degrees C. The thermodynamic parameters such as Delta G degrees, Delta H degrees and Delta S-0 were calculated for the removal process. The negative values of Delta H degrees and Delta G degrees indicates the exothermic and spontaneous nature of the process, respectively. According to these results, the activated carbon synthesized could be used as an alternate to the expensive commercial activated carbon for the removal of textiles dyes from waste water.