Experimental investigation on a combination of soil electrokinetic consolidation and remediation of drained water using composite nanofiber-based electrodes

Abstract

A novel electrokinetic geosynthetic (EKG) can be efficient in achieving multiple objectives. In this study, a new EKG as an electrode and a drainage channel in the electro-osmotic consolidation was fabricated by electrospun nanofibers containing graphene nanoparticles (GNs) attached to a carbon fiber substrate. To investigate the effectiveness of the fabricated electrodes in electro-osmotic consolidation and remediation of water drained from the system, an experimental apparatus was constructed while considering loading capability in expanded ranges and applying the electric field, and was filled with copper (Cu)-contaminated kaolinite. Experiments were divided into control (CT) and EKG groups, and three categories, C-EK, ES₁-EK, and ES₂-EK (using carbon fiber, electrospun nanofibers containing 1 wt% GNs, and electrospun nanofibers consisting of 2 wt% GNs, respectively). All the experiments were conducted with the same conditions, loading, drainage condition, and duration. However, EKG experiments were performed by employing the electric field under the vertical pressure in the range of 7-113 kPa, while the CT was conducted without the electric field. According to experimental results, 18 wt% polymethyl methacrylate in the dimethylformamide solvent containing 1 and 2 wt% GNs was selected for making a nanofibrous layer on the carbon fiber. The average diameters of the fibers were 404 ± 36 and 690 ± 62 nm and yielded at 1 and 2 wt% GNs, respectively. The results revealed that using the EKG accelerated kaolinite consolidation. The average degree of consolidation was 68 and 85% in the CT and EKG experiments, respectively. Furthermore, the fabricated electrodes were highly effective as a drainage channel for remediating water drained from the system. Moreover, the highest Cu removal efficiency was obtained in ES₂-EK (97%) and ES₁-EK (92%), respectively. Conversely, the lowest Cu removal efficiency was observed in the C-EK group (85%).

Keywords: Carbon fiber; Electrospinning; Geosynthetics; Graphene; Removal.