Characteristics of Nitrate Ion Adsorption onto N-doped Activated Carbon Derived from Pinecone and Urea

抄録

Currently, ion exchange resins are widely used to remove nitrate ions from water, but they have problems such as high production cost and difficulty to reuse, so there is a demand for the development of alternative adsorbents. In this study, we attempted to introduce the quaternary nitrogen (N-Q) to the activated carbon using the biomass material to enhance the nitrate ion adsorption in aqueous solution. Then, the relationships between nitrate ion adsorption and equilibrium solution pH (pH_e), the elemental ratio, and the surface functional group contents of the sample were investigated to examine the amount of the N-Q and its effect on nitrate ion adsorption. As a result, the amount of N-Q in the sample increased with raising the ratio of urea to pinecone, and the optimal weight ratio that can introduce a large amount of N-Q into the sample and improve nitrate ion adsorption performance was Pc:Ur:Zn=1:1.5:0.5. The sample prepared with the optimum weight ratio showed high nitrate ion adsorption (0.5 mmol/g) as a carbon material and maintained the high adsorption performance in a wide pH range. These results indicated that the relatively easy preparation method in this experiment efficiently could introduce the N-Q into biomass AC, which promoted nitrate ion adsorption in aqueous solution. Also, it would imply that the influence of N-Q amount on nitrate ion adsorption performance was greater than the specific surface area, which is general indicator of activated carbon adsorption capacity.