Nanobubbles effect on heavy metal ions adsorption by activated carbon

This study investigates the effect of nanobubbles (NBs) on the adsorption in water. In batch adsorption experiments, as liquid medium deionized water, with or without NBs, was used in order to remove a particular heavy metal. Lead ions (Pb(II)) and low-cost activated carbon produced from pyrolysis of potato peels (ACP) were used as model pollutant and adsorbent material, respectively. The adsorption capacity of Pb(II) was found to be approximately similar either in the presence (Q(max)=171 mg/g) or absence of NBs in water (Q(max)=167 mg/g). On the contrary, the major effect of NBs was to accelerate the adsorption process by 366%. This impressively high acceleration will be the basis in future research to decrease the adsorption equilibrium time and sequentially increase the number of adsorption-desorption cycles in reuse modes. A proposed mechanism exported from the experimental results, in which NBs act as carriers ("buses"), was proposed based on the already known theory; the inherent property of NBs to accept charged particles onto their interface is considered to assist diffusion and penetration phenomena of lead ions into the activated carbon pores.