This study focused on the development of an efficient and practical biosorbent, a low cost and promising plant waste with cellulose-lignin polymeric structure, for the treatment of dye containing solutions. Thuja orientalis biomass was modified by citric acid and its biosorption potential was investigated with respect to pH (2.0-10.0), contact time (1-60 min), sorbent dosage (0.01-0.05 g), initial dye concentration (10-725 mg L-1) and flow rate (0.5-4.0 mL min(-1)). Modification significantly increased the biosorption of dye by 30% as compared with unmodified biomass. Kinetic data followed the pseudo-second-order model while the equilibrium data were well predicted by the Langmuir isotherm model. Maximum dye biosorption capacities for natural and modified biomasses were found to be 91.03 and 203.21 mg g(-1) at 30 degrees C, respectively. Modified biosorbent exhibited very good regeneration potential up to 10 cycles and it was successfully used for the decolorization of synthetic solution in dynamic flow mode. Zeta potential measurements, IR, SEM and EDX analysis were used to characterize the possible dye-biosorbent interactions. Overall, the present study underlines the alternative use of modified T. orientalis cones for removal and recovery applications of cationic dye, Basic Blue 9. (C) 2013 Elsevier Ltd. All rights reserved.