Fabrication of magnetic biochar as a treatment medium for As(V) via pyrolysis of FeCl 3 -pretreated spent coffee ground * Dong-Wan Cho a , Kwangsuk Yoon a , Eilhann E. Kwon a , Jayanta Kumar Biswas b , Hocheol Song a, * a Department of Environment and Energy, Sejong University, Seoul 05006, South Korea b Pollution, Ecotoxicology and Ecotechnology Research Unit, Department of Ecological Studies, University of Kalyani, Kalyani, Nadia 741235, West Bengal, India article info Article history: Received 17 February 2017 Received in revised form 5 June 2017 Accepted 24 July 2017 Available online xxx Keywords: Reactive gas Mineral phase change Magnetic biochar Adsorption As(V) abstract This study investigated the preparation of magnetic biochar from N 2 - and CO 2 -assisted pyrolysis of spent coffee ground (SCG) for use as an adsorption medium for As(V), and the effects of FeCl 3 pretreatment of SCG on the material properties and adsorption capability of the produced biochar. Pyrolysis of FeCl 3 - pretreated SCG in CO 2 atmosphere produced highly porous biochar with its surface area ~70 times greater than that produced in N 2 condition. However, despite the small surface area, biochar produced in N 2 showed greater As(V) adsorption capability. X-ray diffraction and X-ray photoelectron spectrometer analyses identified Fe 3 C and Fe 3 O 4 as dominant mineral phases in N 2 and CO 2 conditions, with the former being much more adsorptive toward As(V). The overall results suggest functional biochar can be facilely fabricated by necessary pretreatment to expand the applicability of biochar for specific purposes. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction A concept of utilizing waste biomass for energy recovery has been gaining increasing attention as a sustainable approach to cope with massive amounts of organic wastes generated by human ac- tivities (Kwon et al., 2015). Pyrolysis is considered as a promising fuel processing technique since virtually all biomass wastes can be converted into hydrocarbons such as synthetic gas and oil, which can be further purified and/or upgraded with/without catalytic applications to meet the standard fuel properties. Biochar is another byproduct mainly composed of carbon with highly porous structure and biological/chemical stability (Ghaffar et al., 2015). Due to these favorable properties, biochar has been utilized in agricultural practices including land restoration (Lehmann, 2007), crop yield improvement (Zhang et al., 2014), and soil amendment (Li et al., 2016). The use of biochar as a treatment medium for environmental remediation has attracted much research interests because of its effectiveness and economic feasibility. Despite the material prop- erties varies in largely depending on the type of feedstock biomass and pyrolytic parameters, biochar commonly contains a large number of functional groups capable of binding various type of contaminants (Cho et al., 2016b). Biochar has been tested as adsorbent in the removal of various heavy metals and organic contaminants from water (Clemente et al., 2017; Sun et al., 2016). For example, Clemente et al. (2017) assessed the adsorption per- formance of diverse biochar fabricated in different conditions (feedstock, temperature, reaction time etc.) toward Cd(II), Ni(II), Pb(II), Cu(II) and Zn(II). Sun et al. (2016) examined the adsorption of sulfamethoxazole by biochar in the presence of low molecular weight organic acids. However, most biochar for environmental application exhibit high pH due to the escape of hydrogen molecules as well as the accumulation of highly alkaline mineral ash during pyrolysis (Jung et al., 2016; Luo et al., 2015; Tian et al., 2016), and this limits their application to treat anionic contaminants, especially As(V) that is highly mobile in high pH conditions (Zheng et al., 2012). In addi- tion, carboxyl group, one of the most common functional groups in biochar, has low affinity to As(V). Thus, it is desirable to find suit- able ways to modify or functionalize biochar for better treatment of As(V)-contaminated soils or waters. * This paper has been recommended for acceptance by Dr. Jorg Rinklebe. * Corresponding author. 209 Neungdong-Ro, Gwangjin-Gu, Seoul 05006, South Korea. E-mail address: hcsong@sejong.ac.kr (H. Song). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol http://dx.doi.org/10.1016/j.envpol.2017.07.079 0269-7491/© 2017 Elsevier Ltd. All rights reserved. Environmental Pollution xxx (2017) 1e8 Please cite this article in press as: Cho, D.-W., et al., Fabrication of magnetic biochar as a treatment medium for As(V) via pyrolysis of FeCl 3 - pretreated spent coffee ground, Environmental Pollution (2017), http://dx.doi.org/10.1016/j.envpol.2017.07.079