Biochar oxidation is known as a modification method to enhance the beneficial sorption characteristics of biochar. To explore this, a comparative physio-chemical analysis of non-oxidized and oxidized biochar with hydrogen peroxide (H2O2) was conducted using different feedstocks. Biochars were pyrolyzed at temperatures of 350, 450, and 550 degrees C and were derived from wheat straw, rye straw, wood residues, cherry stone, sewage sludge, and cattle manure, marked as BWS, BRS, BWR, BCS, BSS, and BCM. The pyrolysis temperature of 550 degrees C in BWS and BRS led to the formation of newly arranged vessels and regular pores scattered in their walls. X-ray photoelectron spectroscopy of wood-based biochars showed a notable increase in surface oxygen-contained functional groups for O-BWR350, O-BWR450, O-BWR550, O-BCS350, O-BCS450, and O-BCS550 with increased values by 6.5 %, 27.9 %, 42.3 %, 3.9 %, 31.2 %, and 52.4 % compared to their correspondent non-oxidized biochars. The sharp peaks of crystallization in non-oxidized biochars diminished after oxidation as detected by X-ray diffractometer analysis. Also, Cd removal efficiency in O-BCS550 (65 %) and O-BWR550 (69 %) appeared with outstanding results among all biochar types. Based on thermo-gravimetric analysis, the lowest and highest mass losses on average were related to BRS (22.5 %), and O-BCM (39.7 %). Also, the high heating value (HHV) analysis showed that BWR550 and BCS550 biochars had the highest HHV with 33.6 and 32.5 MJ kg(-1), and O-BSS350 had the lowest value with 10.1 MJ kg(-1). By taking feedstock degradability and pyrolysis temperature into account, this work presents a novel approach to maximize the benefits of H2O2-modified biochar. This will enable us to create a variety of engineered biochars in a clean and economical way as opposed to costly activation oxidants.
