Mechanisms of Transport and Retention of Ball-milled Nano-biochar in Saturated Porous Media
Ball-milled nano-biochar was used to simulate the nano-biochar produced in aging process in this study,and one-dimensional column transport experiments were carried out to investigate the effects of ionic strengths(IS),pH and flow velocity of different background solutions on the transport and retention characteristics of ball-milled nano-biochar in quartz sand porous media.The convective dispersion model and DLVO theory were used to fit the breakthrough and retention curves,and the transport parameters such as deposition rate coefficients were obtained.The results showed that the transport rate of ball-milled nano-biochar was significantly increased under low IS,high pH and high flow velocity conditions.Due to the negative increases of Zeta potentials of both ball-milled nano-biochar and quartz sand under low IS and alkaline environments,which enhanced the electrostatic repulsion between them.In addition,the high dispersion of ball-milled nano-biochar in alkaline environment enhanced the migration of ball-milled nano-biochar.Moreover,the residence time of ball-milled nano-biochar in quartz sand column was decreased with the increase of water flow velocity due to advection diffusion.Meanwhile,the increase of shear force took a disadvantage on the sorption of nanoparticles on quartz sand.
Ball-milled nano-biocharColumn experimentsTransport and retentionMechanism of actionDLVO theoryTransport model
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