(396c) Adsorption Properties of Biochars From Swtichgrass, Hardwood and Softwood with and without Activation

Biochar can immobilize heavy metal ions and toxic organic contaminants from aqueous solution and soil. The adsorption properties of the chars typically depend on the porous structure and surface chemical properties which are, in turn, a function of the feedstock and pyrolysis conditions. We employed the biochars produced in a fluidized-bed fast pyrolysis (FP) reactor at 500 °C with a few seconds of residence time, and slow pyrolysis at 500 °C for 1h and 700 °C for 0.5h with and without activation to study zinc (Zn²⁺) and copper (Cu²⁺) adsorption in both aqueous solution and soil, as well as phenol adsorption in aqueous solution. Biochars were activated via steam at 800°C for 45 min at 3 ml/min water flow rate. The feedstocks from which these biochars were produced included switchgrass (SG), hardwood (HW) and softwood (SW). A quantitative determination of the adsorption properties was obtained using linear Langmuir isotherms, ATR-FTIR, Boehm Titration, BET surface area and SEM. These were used to explain the function of biochar surface functional groups in metal adsorption for biochars with and without activation.