Abstract:
A noxious weed and an agricultural waste material Parthenium hysterophorous serves as a source for the preparation of activated carbon (PAC) for our study. The impregnation ratio used for the chemical activation process was 1:1.5:0.4 (PAC: H2SO4: (NH4)2S208). Characterization of the prepared PAC was done and it was found that it was an effective adsorbent for the removal of organic pollutants. Batch adsorption studies were carried out for the removal of major groundwater pollutants Trichloroethylene (TCE) and Tetrachloroethylene (PCE) from aqueous solutions. For both the adsorbates, predictive capabilities of three types of kinetic models and six types of adsorption equilibrium isotherms were investigated. Optimum adsorption conditions were determined with respect to pH, temperature, adsorbent dose and initial adsorbate concentration for both TCE and PCE. The thermodynamic parameters, AG°, AH° and AS°, were calculated to better understand the nature of the adsorption process. The adsorption of both the adsorbates was found to be following pseudo-second order kinetics with rate constants 0.00032 g mg-1 min-1 and 0.0029 g mg -1 min-1 for TCE and PCE, respectively . Among the six isotherm models examined, Freundlich model gave the best fit for TCE adsorption and Fritz-Schlunder model gave the best fit for PCE adsorption. The negative values of thermodynamic parameters represented the spontaneity, chemical control and exothermic nature of the adsorption process. Under optimum conditions, maximum removal efficiencies of TCE and PCE were found to be 98.64% and 83.75% respectively. From various results, it was established that the prepared PAC was more compatible in the removal of TCE than PCE at similar operating conditions. The study concluded that the prepared PAC is an excellent and effective alternative adsorbent for the removal of TCE and PCE from Industrial wastewater because of its negligible-cost, efficiency and ease of availability.
