[Adsorption property of chitosan composite resin for nitrite-nitrogen].

A novel composite resin of chitosan supported by activated carbon was prepared using the emulsification cross-linking technique. The adsorption properties of the resin for NO2(-)-N were studied. It is found that there are many developed micropores on the surface of the resin. Due to the addition of activated carbon, the bulk density, skeleton density and void ratio of composite resin are lower than those of the chitosan resin.The adsorption capacity of chitosan composite resin is much greater than the simple compounding made up of activated carbon and chitosan resin. When the temperature is lower than 40 degrees C, the adsorption is a physisorption process primarily caused by electrostatic attraction. The adsorption selectivity of composite resin for NO2(-)-N is affected by the concentration and negative charge number of co-existing anions. The adsorption reachs equilibrium in 60 min with a calculated equilibrium capacity of 0.479 mg/g. The adsorption velocity is high while the adsorption capacity is low. When the temperature is higher than 40 degrees C, the adsorption is a chemisorption process which is endothermic, spontaneous and entropy increasing. The adsorption reached equilibrium in 90 min with a calculated equilibrium capacity of 0.700 mg/g. The adsorption velocity drops while the adsorption capacity increases. The chemisorption and physisorption isotherm equations are conformed to the Freundlich model, and the adsorption process accords with second-order kinetic rate mode.