Effect of naphthalene on transport and retention of biochar colloids through saturated porous media

In this study, we conducted batch and column experiments to study the effect of naphthalene on retention and transport of biochar colloids in saturated porous media under different solution chemistry. The results of the batch adsorption experiments showed that the ionic strength and pH had negligible effect on naphthalene sorption onto biochar colloids. The results from the column experiments presented that biochar colloid transport decreased with increasing naphthalene concentrations, the presence of naphthalene in suspensions reduced the mobility of biochar colloids in porous media under various ionic strength and pH conditions. The reason was that nonpolar naphthalene was strongly attached on biochar colloid surface, and further lowered the zeta potential of biochar colloids due to charge-shielding. The findings from this study have important implications for biochar application in naphthalene contaminated soils.