Hierarchically tunable porous carbon spheres derived from larch sawdust and application for efficiently removing Cr (III) and Pb (II)

Waste larch sawdust was used as a starting material for the preparation of carbon spheres with tunable morphologies and porous structures using successive steps liquefaction, resinification, self-assembly, carbonization, and KOH activation. Owing to the evaporation-induced self-assembly (EISA) of soft template (F127) in the presence of larch resin precursor under hydrothermal conditions, spherical particles were formed. The carbon spheres were uniform and possessed a hierarchically micro-mesoporous structure. Mesopores were generated upon decomposition of F127 and micropores were formed upon KOH activation. The diameter of the carbon spheres was in the range of 10-25 mu m, and the vermicular pore size of the carbon spheres had a range of 2.0-5.0 nm (mesopores) and 1.5-2.0 nm (micropores). The carbon spheres had a high surface area of 1064 m(2)/g and a large pore volume of 0.503 cm(3)/g. The adsorption capacities of hierarchically carbon sphere for removal were 70% and 90% for Cr (III) and Pb (II), respectively. (C) 2015 Elsevier B.V. All rights reserved.