Remediation of Copper Contaminated Soils Using Water Containing Hydrogen Nanobubbles

Featured Application Nanobubbles were manufactured by using pressurized hydrogen gas and were applied to soils contaminated with heavy metals, to confirm their function as enhancers. The manufactured nanobubbles remained for an extended period of time. A batch-test experiment revealed that the nanobubbles improved desorption of heavy metals. In addition, when the nanobubbles were used as enhancers in electrokinetic experiments, the nanobubbles had better remediation effects than distilled water (DW). The remediation of heavy metals is expected to have a significant impact when using the nanobubbles. Abstract This basic research study was undertaken to use ecofriendly nanobubbles that can improve the electrokinetic remediation of copper-contaminated soil, as well as to determine that remediation efficiency. The nanobubbles were generated by using pressurized hydrogen gas, and the quantity of hydrogen gas bubble that remained over 14 days was measured. The generated nanobubbles were used as an enhancer to remove a heavy metal on contaminated soil, and their applicability was confirmed. A batch test was used to compare the remediation effects of nanobubbles and distilled water on copper-contaminated soil. The results proved that the nanobubbles are a proper desorption agent for copper-contaminated sand and clay specimens. The solid-liquid ratio and the contact time for desorption of the sand and clay were then respectively determined. A large amount of effluent was obtained from electrokinetic remediation of the sand sample after applying the nanobubbles as an enhancer. The remediation efficiency demonstrated with sand proved to be higher than that for clay. This greater efficiency was attributed to a wider specific surface area, demonstrating the potential use of the nanobubbles as an enhancer for soil contaminated by copper with a large amount of effluent outflow. It was also assumed to be affected by the moving capability of the nanobubbles in the soil layer. Thus, the nanobubbled water can be used to improve the removal of heavy metals from contaminated soils. An ecofriendly enhancer for electrokinetic remediation with a relatively large void ratio and fast flowrate was confirmed by the nanobubbles.