Preparation of MnOx-loaded biochar for Pb2+ removal: Adsorption performance and possible mechanism

In order to increase Pb2+ adsorption capacity of biochar derived from rice husk, the present work explored a facile modification route based on the loading of manganese oxide (MnOx) nanoparticles. SEM, BET, TEM, FTIR and XPS analysis confirmed the successful loading of MnOx nanoparticles onto biochar. The maximum Pb2+ adsorption capacity for MnO loaded biochar (MOLBC) with MnOx coverage of 40% was as high as 86.5 mg g(-1), while that for blank biochar was as low as 14.7 mg g(-1). Specific surface area as high as 340.0 m(2) g(-1) was exhibited by 40%MOLBC, while the specific surface area of blank biochar was only 234.8 m(2) g(-1). The MOLBC demonstrated relatively high adsorption capacity for Pb2+, due to the formation of MnO), sphere complexes especially monodentate, as well as oxygen complexes on biochar surface. Besides this, pi-electron cloud system, decrease of electron density from sr-band of graphenic nature carbon due to addition of-COOH and induced vacancy defect of graphenic basal plane created on biochar surface was also considered to play a key role in Pb2+ adsorption. The results suggested that MOLBC could be promisingly implemented as an environmentally friendly and inexpensive adsorbent for Pb2+ removal from wastewater. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.