Activated carbons were produced from fluid petroleum coke using physical (steam and CO2) and chemical (KOH and H3PO4) activations. Effects of process parameters including activation temperature, activation time period and water flow rate on yield and BET surface area of steam-activated carbons were investigated and optimized. Steam activation improved BET surface area of the precursor more than 40 times at optimum operating conditions and KOH activation increased BET surface area from 11 to 692 m(2)/g. Properties of activated carbons were characterized by BET, SEM, CHSNO, FTIR, ICPMS and Boehm analysis techniques. The steam-activated carbons were treated with HNO3 and H2O2 separately to study the effects of acid treatments on surface chemistry, porous characteristics and environmental applications of activated carbons. Activated carbons produced in this study were used as adsorbent for ammonium ion (40.0 and 260.0 mg/L) in liquid phase and as catalyst for direct oxidation of H2S (10,000 ppm) in gas stream. Among all other samples HNO3 and H2O2-treated samples showed the highest ammonium adsorption by 184.6 and 169.6 mg/g, respectively. The largest breakthrough time (320 min) among all samples was shown by KOH activated carbon. The SO2 production was less than 5% of H2S fed to the reactor. (C) 2012 Elsevier B.V. All rights reserved.