Assessing the efficiency and mechanism of zinc adsorption onto biochars from poultry litter and softwood feedstocks

The efficiency and adsorption mechanism of zinc removal was assessed in aqueous solution using four biochars from multiple biomass residues (poultry litter and three tree species). The effect of pH, kinetic effects, and isotherm fittings were investigated, as well as zinc -laden biochar using x-ray diffraction and absorption near edge structure. Sorbent load results showed softwood biochar exhibited the greatest zinc removal from both deionized (15 mgZn/L) and mining influenced river water (10 mgZn/L). The Langmuir isotherm was the best fit for the majority of the biochars. Exchangeable cations contributed most for the adsorption mechanism from the softwood biochars, while precipitation was greatest contribution for the poultry litter biochar. Overall, our results suggest that biochars from Douglas Fir trees are more efficient at removing zinc from aqueous solutions (up to 19.80 mgZn/g) compared to previously studied biochars (0.61 to 11.0 mgZn/g) and should be used for future remediation efforts.