Journal of Hazardous Materials 290 (2015) 43–50 Contents lists available at ScienceDirect Journal of Hazardous Materials j o ur nal ho me pa ge: www.elsevier.com/locate/jhazmat Enhanced sulfamethazine removal by steam-activated invasive plant-derived biochar Anushka Upamali Rajapaksha a,b , Meththika Vithanage b , Mahtab Ahmad c , Dong-Cheol Seo d , Ju-Sik Cho d,∗ , Sung-Eun Lee e , Sang Soo Lee a , Yong Sik Ok a,∗∗ a Korea Biochar Research Center & Department of Biological Environment, Kangwon National University, Chuncheon 200-701, Republic of Korea b Chemical and Environmental Systems Modeling Research Group, National Institute of Fundamental Studies, Kandy, Sri Lanka c Soil Sciences Department, College of Food & Agricultural Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia d Department of Biological Environment, Sunchon National University, Sunchon 540-742, Republic of Korea e School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Republic of Korea h i g h l i g h t s • Steam activation of biochar enhanced sulfamethazine removal from aqueous media. • Biochar properties varied drastically by the activation with steam. • Solution pH and biochar properties had strong effect on sulfamethazine sorption. • The steam activated biochar produced at 700 ◦ C had the highest sorption capacity. a r t i c l e i n f o Article history: Received 23 October 2014 Received in revised form 10 February 2015 Accepted 15 February 2015 Available online 17 February 2015 Keywords: Activated carbon Black carbon Charcoal Emerging contaminants Slow pyrolysis Veterinary antibiotics a b s t r a c t Recent investigations have shown frequent detection of pharmaceuticals in soils and waters posing poten- tial risks to human and ecological health. Here, we report the enhanced removal of sulfamethazine (SMT) from water by physically activated biochar. Specifically, we investigated the effects of steam-activated biochars synthesized from an invasive plant (Sicyos angulatus L.) on the sorption of SMT in water. The properties and sorption capacities of steam-activated biochars were compared with those of conven- tional non-activated slow pyrolyzed biochars. Sorption exhibited pronounced pH dependence, which was consistent with SMT speciation and biochar charge properties. A linear relationship was observed between sorption parameters and biochar properties such as molar elemental ratios, surface area, and pore volumes. The isotherms data were well described by the Freundlich and Temkin models suggesting favorable chemisorption processes and electrostatic interactions between SMT and biochar. The steam- activated biochar produced at 700 ◦ C showed the highest sorption capacity (37.7 mg g −1 ) at pH 3, with a 55% increase in sorption capacity compared to that of non-activated biochar produced at the same temperature. Therefore, steam activation could potentially enhance the sorption capacities of biochars compared to conventional pyrolysis. © 2015 Published by Elsevier B.V. 1. Introduction Water contamination by antibiotics is becoming a worldwide environmental issue [1,2]. Sulfamethazine (SMT), which belongs to the sulfonamide group of antibiotics, is commonly used in veteri- nary medicine to control diseases and in livestock feeds for cattle ∗ Corresponding author. Tel.: +82 61 750 3297. ∗∗ Corresponding author. Tel.: +82 33 250 6443; fax: +82 33 241 6640. E-mail addresses: chojs@sunchon.ac.k (J.-S. Cho), soilok@kangwon.ac.kr (Y.S. Ok). and swine [3]. Previous studies have shown that, SMT does not sorb to soil well and hence, can be detected at high concentra- tions in water [4]. Remediation of antibiotic-contaminated water has been achieved by sorption processes using various sorbents, including natural sorbents, clays, chitosan derivative, activated car- bon, and more [5–8]. It has been shown that sorption of SMT by clays decreases with increasing pH of solution and increases with increasing ionic strength and surface charge density. Various SMT sorption mechanisms including cation exchange, hydrophobic par- titioning, and surface complexation reactions (H-bonding and other polar interactions) between the functionalities (amino, carboxyl, http://dx.doi.org/10.1016/j.jhazmat.2015.02.046 0304-3894/© 2015 Published by Elsevier B.V.