Removal of nitrite ions from water by adsorption on chemically activated carbon

In the last years more and more attention has been paid to the surface chemistry of the active carbons selected for the adsorption of ions from solution. The purpose of this work was to study the adsorption of nitrite ions from solutions on CAN-7 active carbon that is a mesoporous active carbon with acidic surface due to method of obtaining (chemical activation with phosphoric acid). For the description of the nitrite ions adsorption process on CAN-7 active carbon the influence of various experimental parameters (pH value, initial concentration, and contacting time) was evaluated in batch experiments, at the ratio: liquid solid of 1: 500, the fraction of activated carbon was between 0.8 ÷ 2.0 mm. Adsorption equilibrium data were fitted to Langmuir and Freundlich isotherms and to different kinetic models (pseudo-first and pseudo-second kinetic models and intraparticle diffusion). The equilibrium adsorption data were best represented by the Langmuir isotherm; this means that the adsorption process is dominated by chemosorption on the energetic homogeneous surface.