Review Progress in the preparation and application of modiﬁed biochar for improved contaminant removal from water and wastewater Mohammad Boshir Ahmed a , John L. Zhou a,⇑ , Huu H. Ngo a , Wenshan Guo a , Mengfang Chen b a School of Civil and Environmental Engineering, University of Technology Sydney (UTS), Broadway, NSW 2007, Australia b Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China highlights  Biochar modiﬁcations and subsequent functionality improvement are summarized.  Modiﬁed biochar has shown enhanced sorptive capacity for contaminants.  Continuous column applications for contaminant removal have been examined.  Regeneration methods for modiﬁed biochar have been evaluated.  Future research directions using modiﬁed biochar have been proposed. graphical abstract article info Article history: Received 12 April 2016 Received in revised form 15 May 2016 Accepted 18 May 2016 Available online 20 May 2016 Keywords: Modiﬁed biochar Functionality Sorption isotherms Column operation Regeneration abstract Modiﬁed biochar (BC) is reviewed in its preparation, functionality, applications and regeneration. The nature of precursor materials, preparatory conditions and modiﬁcation methods are key factors inﬂuenc- ing BC properties. Steam activation is unsuitable for improving BC surface functionality compared with chemical modiﬁcations. Alkali-treated BC possesses the highest surface functionality. Both alkali modi- ﬁed BC and nanomaterial impregnated BC composites are highly favorable for enhancing the adsorption of different contaminants from wastewater. Acidic treatment provides more oxygenated functional groups on BC surfaces. The Langmuir isotherm model provides the best ﬁt for sorption equilibria of heavy metals and anionic contaminants, while the Freundlich isotherm model is the best ﬁt for emerging con- taminants. The pseudo 2 nd order is the most appropriate model of sorption kinetics for all contaminants. Future research should focus on industry-scale applications and hybrid systems for contaminant removal due to scarcity of data. Ó 2016 Elsevier Ltd. All rights reserved. Contents 1. Introduction ......................................................................................................... 837 2. Biochar surface modification methodologies ............................................................................... 837 2.1. Steam activation ................................................................................................ 837 2.2. Heat treatment ................................................................................................. 837 http://dx.doi.org/10.1016/j.biortech.2016.05.057 0960-8524/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: junliang.zhou@uts.edu.au (J.L. Zhou). Bioresource Technology 214 (2016) 836–851 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech