Characterization and optimization of activated biochars from wheat straw pellets: Effects of treatment durations and post-washing

Biochar is a sustainable option for managing agricultural biowastes, and its performance depends on effective activation. This study investigates how ball milling and hydrogen peroxide treatments (30–120 min), with and without washing, modify the physicochemical properties of wheat straw biochar. Ball milling for 120 min followed by washing enhanced structural specific surface area (32.86-fold), pore volume (9.31-fold), and conductivity (3.34%), while 30 min milling followed by washing improved carbon stability, increasing fixed carbon by 42.30%. Hydrogen peroxide treatment primarily improved surface functional properties, boosting cation exchange capacity 6.6-fold at 120 min and, with washing, increasing O/C ratio and carboxylic groups while reducing ash content. Optimization of the two activation methods, with and without post-washing, identified optimal times of 89.3–93.4 min (desirability >0.8). At this optimum, ball-milled biochar offered the highest conductivity and surface area, while hydrogen peroxide-activated biochar achieved the greatest chemical functionality, supporting diverse agricultural and environmental applications. • Two activation methods were tested with and without washing. • Ball milling enhanced conductivity, surface area, and dispersibility. • H 2 O 2 increased oxygen groups and cation exchange capacity. • Washing removed ash and improved fixed carbon and surface area. • 89.3–93.4 min treatment maximized CEC, carboxylic groups, and O/C ratio.