Effects of pyrolysis temperature on soybean stover- and peanut shell-derived biochar properties and TCE adsorption in water Mahtab Ahmad a , Sang Soo Lee a , Xiaomin Dou b , Dinesh Mohan c , Jwa-Kyung Sung d , Jae E Yang a , Yong Sik Ok a,⇑ a Korea Biochar Research Center, Department of Biological Environment, Kangwon National University, Chuncheon 200-701, Republic of Korea b Department of Environmental Science and Engineering, Beijing Forestry University, P.O. Box 60, Beijing 100083, PR China c School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India d National Academy of Agricultural Science, RDA, Suwon 441-707, Republic of Korea highlights " Pyrolysis temperature influenced crop residue-derived biochar (BC) properties. " High pyrolysis temperature led to increased surface area and aromaticity of BC. " TCE adsorption capacity was related to aromaticity and polarity of BC. article info Article history: Received 20 January 2012 Received in revised form 9 May 2012 Accepted 11 May 2012 Available online 18 May 2012 Keywords: Crop residue Biomass Carbonization Proximate analysis Agricultural waste abstract Conversion of crop residues into biochars (BCs) via pyrolysis is beneficial to environment compared to their direct combustion in agricultural field. Biochars developed from soybean stover at 300 and 700 °C (S-BC300 and S-BC700, respectively) and peanut shells at 300 and 700 °C (P-BC300 and P- BC700, respectively) were used for the removal of trichloroethylene (TCE) from water. Batch adsorption experiments showed that the TCE adsorption was strongly dependent on the BCs properties. Linear rela- tionships were obtained between sorption parameters (K M and S M ) and molar elemental ratios as well as surface area of the BCs. The high adsorption capacity of BCs produced at 700 °C was attributed to their high aromaticity and low polarity. The efficacy of S-BC700 and P-BC700 for removing TCE from water was comparable to that of activated carbon (AC). Pyrolysis temperature influencing the BC properties was a critical factor to assess the removal efficiency of TCE from water. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Biochar (BC) is biomass-derived black C that has been recently recognized as a multifunctional material related to C sequestration, metal immobilization, and fertilization in soils (Awad et al., 2012; Chen et al., 2011; Uchimiya et al., 2010). Biochar is produced by thermal decomposition of biomass under a negligible or limited supply of oxygen (Novak et al., 2009). Various types of biomass including poultry litter, dairy manure, sewage sludge, and paper sludge have been used to produce BCs. The diverse natured BCs are being commonly applied to soils as conditioners; however, their use in soil and groundwater remediation is very scarce. The proper strategies of BCs applications are needed because of the variation in BCs’ characteristics. For example, the crop residues originated from agricultural byproducts are essential sources to maintain the plant nutrition cycle in soils and to sustain soil qual- ity or crop yield (Ok et al., 2011). However, an excessive supply of crop residue also causes environmental pollution when burned di- rectly in the field, dumped into the ocean or fertile land (Karlen et al., 2009). As a possible solution, the excessive crop residues may be transformed efficiently to bioenergy via pyrolysis. An esti- mated 5.7  10 5 tons of crop residue was used for biofuel produc- tion in Korea in 2009 (Kim et al., 2010). The BC being generated as a by-product during bio-oil production would offset the associated environmental problems and contribute to mitigate climate change with lower CO 2 emission (Boateng et al., 2010). Application of BC immobilizes heavy metals and herbicides in soils (Ahmad et al., 2012a; Cao and Harris, 2010). One of the most important functions of BCs is their capability to adsorb organic pol- lutants from the surrounding environment (Chen et al., 2011). The 0960-8524/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.biortech.2012.05.042 ⇑ Corresponding author. Address: Korea Biochar Research Center, Department of Biological Environment, Kangwon National University, 192-1 Hyoja 2-Dong, Chuncheon 200-701, Republic of Korea. Tel.: +82 33 250 6443; fax: +82 33 241 6640. E-mail address: soilok@kangwon.ac.kr (Y.S. Ok). Bioresource Technology 118 (2012) 536–544 Contents lists available at SciVerse ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech