Determination of Optimum Temperature in Fast Pyrolysis for the Yield and Properties of Rice Husks Biochar.

For a poster presentation at

ASA, CSSA, & SSSA International Annual Meetings, Tempa, Florida, USA, Nov. 3-6, 2013

Determination of Optimum Temperature in Fast Pyrolysis

for the Yield and Properties of Rice Husks Biochar

Young-Jin Seo¹, Dong-Cheol Seo¹, Se-Won Kang¹, Sang-Gyu Lee¹, Ju-Wang Park¹, Ik-Won Choi¹, Ju-Dong Yang¹, Jae-Woo Park¹, Jong-Soo Heo², Ju-Sik Cho^1*

¹Department of Bio-Environmental Sciences, Sunchon National University, Sunchon, Korea,

²Division of Applied Life Science (BK21 program) & Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, Korea

Abstract

Biochar that is obtained by heating organic compounds in anaerobic condition has the potential both to improve power of soil and to mitigate greenhouse gases emissions (GHG) from soil. Although biochar also has lots of inorganic components for soil management and plant growth, the contents of inorganic components of biochar change according to pyrolysis temperatures. Biochar with process temperature suited to plant growth should be produced. Then, to determinate of optimum temperature in fast pyrolysis, the yield and properties of rice husks biochar pyrolyzed at 300, 500 and 700°C for 1 hr were investigated. The yield of rice husks biochar was 53.5% at 300°C, 39.8% at 500°C and 36.5% at 700°C. pH of rice husks biochar at 300, 500 and 700°C were 7.43, 10.75 and 11.03, respectively. EC of rice husks biochar were high in the order of 700°C (30.0 dS m^-1) > 500°C (15.6 dS m^-1) > 300°C (2.1 dS m^-1). The concentration of N in rice husks biochar produced at 300°C (0.40%) was higher than other temperatures. The concentration of P in biochar obtained from pyrolysis of rice husks at 700°C (0.23%) was higher than that at 300 (0.05%) and 500°C (0.08%). The concentrations of K in rice husks biochar at 300, 500 and 700°C were 0.48, 0.97 and 2.89%, respectively. At 700°C, P and K have similar trend. The concentration of all heavy metals (Zn, Pb, Ni, Hg, As and Cd) as total elements was found to increase with increasing temperature. Temperature in fast pyrolysis also had an effect on enrichment of heavy metals in the rice husks biochar. Therefore, optimum temperature of rice husks biochar in fast pyrolysis was 300°C considering the yield, biochar properties and energy saving effect.

*Corresponding Author. Ju-Sik Cho, Department of Bio-Environmental Sciences, Sunchon National University in Korea.

Tel.: +8261-750-3297; Fax: +8261-752-8011; E-mail: chojs@sunchon.ac.kr.

Keywords: Biochar, Rice husks, Pyrolysis, Temperature