Optimization of activation by peroxidation and photo-assisted peroxidation of biochar produced from sewage sludge

Biochar from biomass, a cost-effective and sustainable alternative to pulverized activated carbon (PAC), often faces limitations in pore size and surface functionality. Hydrogen peroxide (H2O2) activation can enhance biochar's surface properties but requires large quantities and high concentrations, increasing production costs. Advanced oxidation methods, such as H2O2/UV radiation, can reduce H2O2 usage by generating highly reactive hydroxyl radicals (*OH). This study investigates biochar production from activated sewage biosolids using H2O2 activation and H2O2/UV radiation. Optimization was conducted via a central composite rotational design, varying activation parameters activation pH (1.5, 4.0, 7.0, 9.0, and 11.5) and H2O2 concentration (0, 10, 20, 30, and 40 vol), with methylene blue (MB) adsorption capacity as the metric. Characterization was performed using FTIR, SEM, EDS, XRD, and N2 adsorption/desorption techniques. Results indicated optimal biochar activation at pH 11.5 with 20 vol% H2O2. Activation pH was more significant than H2O2 concentration. Desirability curve analysis suggested that optimized parameters did not significantly enhance adsorption capacity, with desirability values at 93.053 %. Overall, H2O2 efficiently increased surface area by degrading the adsorbent, while H2O2/UV effectively removed impurities.