Carbon nanotubes (CNTs) and La/CNTs composite as adsorbents were synthesized and characterized by FTIR, SEM, and BET analysis and literally were applied for the removal of nitrate from aqueous solutions at different conditions. Taguchi's method of design of experiments was used to study the effect of each parameter at three levels on the total amount of nitrate adsorption on adsorbents. The effects of important variables such as pH, temperature, initial concentration of nitrate, and contact time on adsorption process were optimized by Taguchi approach. Optimum values of 3, 00C, 10 ppm and 210 min were obtained for pH, temperature, initial concentration of nitrate, and contact time, respectively. At the optimized condition, the removal efficiencies were found to be 65.15% and 93.37% for CNTs and La/CNTs, respectively. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. Equilibrium data fitted well with the Langmuir model.
