We report a facile synthesis of nanoporous activated carbons (NACs) derived from Lapsi (Choerospondias axillaris) seed powder (LSP). LSP and sodium hydroxide (NaOH) are mixed in 1:1 ratio by wt. and carbonized at 400 degrees C for different time (3, 4, and 5 h) and at different temperature (400, 500, 600, and 700 degrees C) for 3 h under a constant flow of ultrapure nitrogen gas. The effect of the conditions during the preparation on the structures and properties of NACs is investigated carefully. Fourier transform infrared spectroscopy (FT-IR) show the presence of several functional groups (e.g., hydroxyl, carbonyl, and carboxyl groups) on the carbon surface. Irrespective of the carbonization conditions, both D and G bands are clearly observed in Raman scattering spectra. It is found that the increase in carbonization time significantly increases the G/D bands ratio, indicating an enhancement in the graphitic character. The NACs prepared by carbonization at 400 degrees C for 3 h have the highest surface area (over 1000 m(2) g (1)) and show high adsorption efficiency in removing methylene blue (MB) from aqueous solution (around 200 mg g (1)). (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B. V. and The Society of Powder Technology Japan. All rights reserved.