Removal of safranin basic dye from aqueous solutions by adsorption onto corncob activated carbon

Adsorption of a basic dye, safranin, from aqueous solutions onto activated carbon prepared from corncobs (ACCC) has been investigated. Various experiments have been carried out using batch adsorption technique to study the effects of the process variables, which include initial pH, adsorbent dosage, initial dye concentration, particle size, temperature, and agitation speed, on the adsorption process. The adsorption of safranin onto the adsorbent was found to improve with the increase in adsorbent dosage and finer mesh size. Maximum adsorption was observed at pH > pH(zpc) in the pH values ranging from 5 to 9. It was observed that the rate of adsorption improves with increasing temperature and the process is endothermic with an Delta H value of 35.698 kJ/mol. The kinetics followed is first order in nature. The results showed that both Langmuir and Freundlich isotherms fit the equilibrium data. Also, the results revealed that activated carbon from corncob, an agricultural waste biomass, proved to be an excellent low-cost sorbent.