Characteristics of Nitrate Sorption onto Activated Carbon

The potential of activated carbon (a product of Merck) as an adsorbent has been studied for removal of nitrate from some polluted water sources. In line with this purpose, nitrate sorption kinetics and isotherms, as well as the effects of contact time, initial concentration, pH and temperature on nitrate sorption onto activated carbon were investigated. The surface characteristics of activated carbon were also studied, through FTIR and SEM techniques. Two simplified kinetics models, namely: pseudo-first and pseudo-second orders were tested to investigate the sorption mechanisms and while two isotherm models namely Freundlich and Langmuir employed to describe the equilibrium sorption of nitrate onto activated carbon. The results revealed that the amount of nitrate sorption increased with time and reached its maximum after ten minutes past. Maximum nitrate sorption occurred in a neutral pH figure, and with either increase or decrease in the pH level, the amount of sorption being decreased. The amount of nitrate sorption increased with a decrease in temperature, level, the depicting the exothermic nature of sorption. A comparison of the coefficient of determination of the fitted equations indicated that pseudo-second order equation (R2=1.000) was better fitting than pseudo-first order equation (R2=0.839) for description of nitrate sorption data. Sorption isotherm was proper, as described by Langmuier model (R2=0.998) and the maximum sorption parameter equaled 8.93 mg per gr of activated carbon.