Adsorption characteristics of NH4-N by biochar derived from pine needles

Yun-Gu Kang1   Jun-Young Lee1   Jin-Hyuk Chun1   Jae-Han Lee1   Yeo-Uk Yun2,*   Taek-Keun Oh1,*   

1Department of Bio-Environmental Chemistry, College of Agriculture and Life Science, Chungnam National University, Daejeon 34134, Korea
2Chungnam Agricultural Research and Extension Services, Yesan 32418, Korea


Nitrogen applied to soil is highly prone to leaching and volatilization leading to gaseous emissions of nitrous oxide (N2O) and ammonia (NH3) which are of great environmental concern. Usage of biochar to reduce the discharge of nitrogen to the environment has attracted much interest in the recent past. Biochar is produced by pyrolyzing various biomasses under oxygen-limited conditions. Biochar is a carbonized material with high adsorptive powers for not only plant nutrients but also heavy metals. The objective of this study was to investigate the adsorption characteristics of NH4-N onto biochar made from pine needles. The biochar was produced at various pyrolysis temperatures including 300, 400 and 500℃ and holding times of 30 and 120 minutes. The Langmuir isotherm was used to evaluate the adsorption test results. The chemical properties of the biochar varied with the pyrolysis conditions. In particular, the pH, EC and total carbon content increased with the increasing pyrolysis conditions. The rate of adsorption of NH4-N by the biochar decreased with the increasing pyrolysis conditions. Of these conditions, biochar that was pyrolyzed at 300℃ for 30 minutes showed the highest adsorption rate of approximately 0.071 mg·g-1. Thus, the use of biochar pyrolyzed at low temperatures with a short holding time can most efficiently reduce ammonia emissions from agricultural land.

Figures & Tables

Fig. 1. Adsorption ratio of NH-N and adsorption amount by mass of biochar.